The quality of a particular product is largely determined by the means of its manufacture. In the engineering industry, the technical characteristics of machine tools and related equipment, which are directly involved in the processing, assembly and assembly of products, are of particular importance. But also an essential role, from the point of view of ensuring the quality of the result, is played by technological equipment, which is a whole range of accessories for the main production units.
General information about technological equipment
The category of technological equipment includes both independent equipment and built-in components, the function of which is reflected in the quality of the production process. As for individual units, they can also contribute to the characteristics of the line operation in an indirect way, without being directly related to its capacity. Now it is worth considering what functions are performed by technological equipment and tooling as part of a production complex. Its main tasks are to maintain the standard quality of manufactured products, increase production volumes, minimize and facilitate the labor of service personnel, etc. These goals are achieved by more efficiently performing preparatory operations using tooling elements, expanding the technological capabilities of machines, reducing processing time blanks and other improvements in the production process.
Equipment types
The basic division of technological equipment is made on the basis of purpose. In particular, there are control, assembly, machine tool, fastening and moving elements of equipment equipment. The control tooling serves as an auxiliary component at the stage of auditing a manufactured product for compliance with standards. Assembly devices increase the efficiency of assembling finished elements into a single structure, device or complex. The most common machine tooling, the presence of which affects the improvement of certain characteristics of the manufactured product - for example, strength, wear resistance or durability of the bearing. Additional fixing devices, in turn, improve the technique of fixing the same workpieces during processing or movement within the production site. Accordingly, the moving tooling is an element of the logistics infrastructure and is responsible for the stability and accuracy of the movement of products along the same conveyor line.
Tooling automation
Previously, the functions of the tooling were assigned mainly to technical means designed for manual handling. Then more efficient and productive mechanized counterparts appeared. On the the present stage In the development of technological processes, tooling is increasingly endowed with automation functions. It is important to note that the driving source of automation is the main equipment, which controls its main units according to the same principle. At the same time, the technological equipment can work according to combined model, and in semi-automatic mode. In such cases, a partially implemented principle of mechanized control is also envisaged. For this, hydraulic or pneumatic drives are used. One way or another, but almost all modern enterprises are actively switching or have already switched to the application of the concept of automated control.
Production of technological equipment
Typically, the technological process of manufacturing tooling elements is based on the use of special strains and litforms, which allow the serial production of products. Again, to work with non-standard fixtures, the form itself can be developed separately with specific parameters defined in the project. Of course, shaping production technological equipment does not end. This can be followed by the stages of milling, turning and heat treatment, which make it possible to bring the workpiece to the required operational state. In Russia, many enterprises are engaged in the manufacture of this kind of tooling. For example, a tooling plant in Yaroslavl (YaZTO) is engaged in the production of combined, shaping and dividing dies, on which it also manufactures large-sized products. The Moscow company "Elton", the Belgorod enterprise "Ritm" and many other plants, one way or another connected with metalworking, are also working in this direction.
Conclusion
Often, the work on the introduction of tooling into production facilities is costly. And by itself, high-quality technological equipment with automation elements can make up almost half of the cost of all equipment at an enterprise. But practice shows that the competent use of auxiliary means fully justifies itself. In addition, in factories with outdated equipment, the use of modern devices is the only way improving the quality of products. - these are high-quality and proven products from well-known world. It is very important that we cooperate with suppliers for a long time, therefore we offer exclusively with a guarantee - in bulk and at minimum low prices. The equipment for lathes is presented - chucks, rotating centers, racks and gears, cams, tool holders.
More details can be found by calling +7 8482 999-111 or send or by e-mail[email protected] site
The productivity and accuracy of processing parts on metal-cutting machines largely depends on their equipment with technological equipment, i.e. from the designs of machine tools, which should, at low cost for their design, manufacture and operation, ensure the receipt of high-quality parts. In addition, they should help to alleviate working conditions and increase its productivity by reducing machine and auxiliary time. This is achieved through the use of multi-tool, group or continuous processing of parts, the introduction of high-speed cutting modes, the use of quick-acting clamps with a mechanical, pneumatic, hydraulic or pneumohydraulic or pneumohydraulic drive.
The use of mechanized drives ensures fast and reliable clamping of workpieces and allows you to automate machining cycles. The latter is especially important for multi-station service and mass introduction of high-speed cutting modes in factories.
The use of devices allows: to eliminate the marking of workpieces before processing, to increase the accuracy of processing, to reduce the cost of production, to facilitate the working conditions and ensure its safety, to expand the technological capabilities of the equipment, to apply technically justified time norms, to reduce the number of workers required for production.
In large-scale and mass production, there are on average up to 10 fixtures for each part.
The study of the course "Technological equipment" is based on the study of disciplines: mechanical engineering drawing, machine parts, metal cutting, metal-cutting machines, mechanical engineering technology. Knowledge of the basics of technological equipment is very significant, because every mechanical engineer working in the field of mechanical engineering needs to know the methodology for designing high-performance devices, be able to make the necessary strength calculations and guarantee the required accuracy of processing parts in the device.
The designer of fixtures should be able to make extensive use of normalized parts, assemblies and assemblies of fixtures, thereby reducing the complexity of design work and metal consumption.
The design of the fixtures depends on many factors: the program for the production of parts, equipment, the availability of normalized parts and assemblies, the content of the operations performed, etc. pneumatic, hydraulic, pneumo-hydraulic equipment and drive.
The cost of manufacturing devices reaches 15-20% of the cost of equipment. 80-90% of the total park of devices is used for setting and fixing workpieces to be processed.
A device in mechanical engineering is called auxiliarydevices designed for basing and fixing the workpiecerelative to the cutting tool machine.
The use of devices allows:
Ensure the consistent quality of the processed workpieces.
Reduce the time for making a part.
Expand the technological capabilities of the equipment i.e. using devices on conventional universal machines it is possible to perform such work and obtain such accuracy that cannot be obtained under normal conditions without the use of devices.
For instance:
a) using a multi-spindle head on an ordinary vertical drilling machine, we get a multi-spindle drilling machine.
b) with the help of boring jigs, it is possible to obtain high dimensional accuracy on a worn boring machine.
Machine tools allow you to reduce the cost of manufacturing a part due to the use of workers of lower qualifications, eliminate the time-consuming operation of marking, significantly reduce the auxiliary time T aux
According to the Experimental Research Institute of Metal-Cutting Machine Tools (ENIMS), in recent years, cutting has doubled and three times, this is how much the main time has decreased, and labor productivity in mechanical engineering has increased insignificantly. This discrepancy is a consequence of the neglect of auxiliary time, which in some operations reaches 30-40% of T PC
Methods for setting workpieces on the machine
1. Installation of the workpiece directly on the machine table or in a universal device with the alignment of its position relative to the machine table and tool. This method is time-consuming and is used in single and small-scale production, when it is not economically feasible to manufacture a special device.
Installation accuracy for parts up to 3 meters in size on untreated surface is ± 1.5 mm, on treated surfaces ± 0.1 mm.
2. Installation of the workpiece on the machine according to the marking. Marking is called drawing on the workpiece axes and lines that determine the position
processed surfaces. When marking, the workpiece is covered with chalk paint, after it dries, the workpiece is placed on a marking plate, in a prism or square, and lines are drawn on the surface using a caliper, compass, square, caliper with sharp sponges and other tools. In order for the lines to be visible in the case of removing paint along the line, core points are applied at some intervals. Marking requires a significant investment of time of highly qualified specialist markers, on whose individual qualities the marking accuracy depends. The marking device does not provide high processing accuracy. This method is used in the processing of large-sized workpieces in one-off and small-scale production. Accuracy of processing according to the marking of parts with an overall dimension of up to 3m ± 0.5 mm.
3. Installation of the workpiece in a special device. This method of installation ensures the attachment and clamping of the workpiece with a sufficiently high accuracy and with little time. Installation and clamping of the workpiece on machines using special devices it is much easier and faster than installation and fixing directly on the machine table. The use of a special device ensures the highest and most stable machining accuracy for all parts produced with their help, thanks to which the interchangeability of parts is to the greatest extent ensured. In addition, the use of devices allows processing at higher cutting conditions, significantly reducing T vp, including the measurement of the details of the process
processing.
Classification of fixtures
Machine tools are classified by purpose and by degree of specialization. According to their intended purpose, they are subdivided:
1) machine tools - for basing and fixing parts. Depending on the type of processing, they are divided into
a) turning,
b) milling,
c) drilling, etc.
2) auxiliary - intended for the installation of the cutting tool (these are side rods, adapter sleeves, etc.)
Assembly - for connecting mating parts.
Control to control parts and assemblies.
Transport - for gripping, moving, turning over parts, these devices are mainly used in automatic lines.
Depending on the scale of production and technological factors, machine tools are subdivided by specialization
1. Universal - designed to equip the production of dissimilar parts within a certain range of overall dimensions.
For example: machine vices, universal chucks, rotary tables, dividing heads, centers, etc.
Specialized - designed to equip the production of parts of a certain type or typical operations, for parts of several related types.
Special - designed to equip the production of one specific part.
In the conditions of small-scale and serial production, universal assembly devices (USP) acquire a special role. With their help, you can ensure high processing accuracy. USP elements are normalized and included in mechanical engineering norms
In the conditions of serial production, the system is used UNP-universally - adjustment devices. This system is based on the use of replaceable installation and guiding elements (assemblies). The setting elements can be adjusted for set-up purposes for processing workpieces of various types and sizes. When a new batch of parts is launched, the UNP is not removed from the machine, but only replaceable elements are rearranged or adjustable stops are installed. As a result, the preparatory and final time is shortened and the use of machine equipment in time is improved. UNP - consists of two parts, universal and commissioning.
Elements and mechanisms of devices
Machine tools consist of the following basic elements and mechanisms.
Positioning or supporting elements - they serve to position and center workpieces relative to the cutting tool. These include: support plastics, fungal supports, self-aligning and underwater supports, centers, prisms, locating pins, etc.
Clamping elements - used for direct clamping of workpieces. These include: clamps, slats, cams, eccentrics, collets, plunger clamps.
3. Drive mechanisms - they are mechanical, hydraulic pneumatic, pneumohydraulic, vacuum and others.
4. Elements for determining the position and direction of the cutting tool - settings, dimensions, jig bushings.
Auxiliary mechanisms of devices - lifters, dividing devices, clamps.
Appliance housings.
Installation elements.
Requirements for the installation elements: 1. Long-term preservation of accuracy and relative position
surfaces. 2 They must be economically viable, that is, cheap to repair.
It is not allowed to use the raw (not heat-treated) body in the device as mounting supports.
Increased wear resistance. The material for the manufacture of the installation elements is U7A, 2 ОХ steel, followed by carburizing to a depth of 0.8-1.2 mm and quenching to a hardness of 50-55 units The basis for the choice of material is the diameter of the support. easily removable. Supports in the amount of 6 pcs. installed at a maximum distance from each other.
The following are used as installation elements:
support pins;
plates;
3 locating pins; 4. prisms, etc. Installation elements are divided into basic and additional. Additional elements are put into operation only after the part has taken a certain position on the main supports.
Main supports Support pins with flat, spherical and grooved heads are used as the main supports.
Flat head
P 
The above pin is used for installation not large parts with treated surfaces.
WITH spherical surface
The landing dimensions are the same.
The landing dimensions are the same. These pins are used to mount small and narrow parts With slotted heads
Grooved pins are used to position the workpiece on rough surfaces.
The round pins ensure the correct position of the work surfaces in relation to the cutting tool, even with uneven mounting surfaces.
Disadvantages of pins:
1. The workpiece may be damaged by high clamping forces. The clamp should be carried out only on supports or strictly between two
2. Possibility of workpiece upsetting due to the presence of contact defects in
places where the supports touch the mounting surface.
Limit diameters of standard pins d = 3 -24mm, head diameter
D = 5 40mm, height of low heads 1 = 2-20mm, high 1 = 5-40mm, total
length of pins with low heads L = 6-50mm, with high ones L = 9-70mm.
The pins in the body of the device are installed according to the quality I v 6.
The support pads in the body for the pin heads should protrude slightly and be machined at the same time, which ensures that the pins are in the same plane. The pins with a flat head, after being pressed in, are also ground at the same time, in connection with which these pins in size 1 leave an allowance of 0.2-0.3 mm for grinding after assembly.
With intensive use of the device, when the pins quickly wear out, a hardened steel bushing is pressed into the hole of the body.
The ends of the bushings are simultaneously ground providing the necessary flatness, and the height £ of the heads of the pins is performed with a deviation of h 6 or h 5, thus ensuring the interchangeability of the pins at which
makes it necessary to grind their mounting surfaces during assembly and reduce the time for repairing the device. In the holes of the bushings, the pins are installed according to fits or
Base plates For the installation of large parts, support ones are used. There are two types of base plates used in mechanical engineering.
1) without grooves,
2)
with oblique grooves. 
Sizes of standard plates: width B = 12-35mm; length L = 40-210mm; height H = 8-25mm; h = 4-13mm; h 1 = 0.8-Zmm, b = 9-22mm;
d = 6-13mm; d 1 = 8.5-20mm.
The plates are fixed with two or three screws; limiting screw sizes from M6 to M12mm.
Plates without grooves are installed on the vertical walls of the housing. When installed on horizontal walls, chips may get into the screw hole, and therefore installation error.
Plates with oblique grooves are installed on the horizontal surfaces of fixtures. With this design of the plates, the chips move when the part to be moved is installed, easily falls into the recesses (oblique grooves) of the plates and does not break the contact of the workpiece with the plate.
Plates, like pins, are fixed on the protruding pads of the body; if there are several pads in the same plane, they are processed together.
The number of supports and their location are selected in accordance with the basing schemes. In all cases, when designing devices, it is necessary to provide conditions for easy removal of chips from the mounting surfaces.
Auxiliary supports. These supports are used in addition to the main ones when it is necessary to increase the rigidity and stability of the workpiece being installed. Structures of auxiliary supports and their parts are normalized. Auxiliary support
is brought into contact with the workpiece after its installation on the main
supports, and then fixed.
In the mechanization and automation of devices, auxiliary supports are controlled using a pneumatic or hydraulic drive. In some cases, supports and clamps are sequentially triggered from one drive.
Jack - adjustable support
Screw jack with hole These jacks are used when machining parts with a hole
to exit 
Self-aligning supports
Supports for the installation of external and cylindrical parts
surfaces
1.Installation pins
Dowel pins are used when installing workpieces along the base cylindrical holes. In practice, the most widespread are two cases of installations: a) centering and turning the workpiece along two holes; b) centering on one hole and turning along the base plane.
Structurally, the fingers are separated:
locating pins, cylindrical, constant;
cut off permanent adjusting fingers;
locating pins, cylindrical, replaceable;
cut-off adjusting fingers, replaceable.
Three pin modifications are available depending on the diameter of the mounting surface.
Cylindrical
2) diameter over 10mm.
3) diameter over 20mm
1
) diameter up to 10mm.
Replaceable locating pins
Permanent fingers are pressed into the body of the device by square
H1 literature - and the diameters of their mounting surfaces are performed with a deviation
by h6 or f9.
Replaceable pins are used for intensive use of attachments, when the mounting surfaces quickly wear out.
TPP
The pins are mounted in the hole of the bushing according to the quality -, diameters
sq.
mounting surfaces are also performed with deviations in h6 or f9. When installing heavy parts, when stationary fingers interfere with the loading of the device, the fingers are made retractable
Diagram of the combination of fingers with base plates
Installation example for end and hole
An example of installation along the end and two fingers, one cylindrical, and the second cut.Placing the workpiece on two parallel cylindrical holesaxes and on a plane perpendicular to them.
This scheme is used when processing small and medium-sized workpieces such as bodies, plates, frames and crankcases .. Its advantages: simple device design, the ability to fully maintain the principle of constant bases at various operations of the technological process and relatively transfer and fixation of workpieces on flow and automatic lines ...
Compared to the six-point setting, this scheme provides a greater accessibility of the cutting tool to the workpiece from different sides. The workpiece is secured by applying a clamping force perpendicular to its reference plane. This stability scheme is only suitable for workpieces with the dimensions of the reference plane larger or comparable to their height.
Usually two fingers are used because a larger number does not increase the accuracy of the installation of the part, and the manufacture of the fixture becomes more complicated.
The possibility of skewing parts by an angle creates a positioning error E, which affects the dimensional accuracy when manufacturing a part.
The cut-off drill ground makes it easier to bend around the part, because the resulting additional gap compensates for the manufacturing error in dimension L.
B - the width of the guide belt on the cut finger.
where: Smin is the gap in the interface between the cylindrical pin and the hole of the workpiece;
Smin is the minimum clearance at the mating of the cut pin and the hole of the workpiece;
Base hole center-to-center tolerance; tolerance for center-to-center distance of locating pins.
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Basing a part on a hole large diameter via
fingers.
In group devices, the fingers can be rearranged to other diameters.
Tapered locating pins
1. Self-aligning fingers. They are used when basing with a tapered hole or untreated cylindrical holes.
2. Retractable
Placing the workpiece on the center slots
When machining shafts and some other parts based on center seats (tapered chamfers), centers with an angle equal to 60 are used as locating elements.
Installation on a rigid center.
Installation with a tapered chamfer on a cut center.
Special center with three narrow ribbons for the rough base.
Design leash center transmitting torque from indentation of corrugations into the surface of the conical chamfer. This center provides the torque required for finishing, but spoils the surface of the base chamfer.
The design of the driving center where the moment is transmitted through corrugations pressed into the end plane of the workpiece.
Corrugation pos. 1 are made in three sections with a self-aligning washer pos. 2. Center of pos. 3 of the floating structure is mounted in the intermediate sleeve pos. 4. The center is made of steel 45, U6A, U8A and is heat treated to a hardness of HRC 55-60. The wear resistance of the centers can be increased by hardfacing. Maintaining the correct shape of the rear center socket during turning is ensured by the use of rotating centers.
Rigid mandrels
With the development of the accuracy and speed of machines, the requirements for the concentricity of the surfaces of the parts increase. In many cases, the permissible misalignment of surfaces is less than 0.01 mm. This accuracy is achieved by the use of centering devices.
Let's consider some of them so-called rigid mandrels.
1 .Conical mandrels- are used to obtain a high concentricity of the treated surfaces when performing finishing operations.
The taper of such mandrels.
3 2000 4000
The part is secured by light blows of the end face against a wooden lining. The hole in the workpiece is made according to the quality H6 - H7. As a result of the wedging action, the workpiece is firmly kept from turning during processing; centering accuracy 0.005 - 0.01 mm.
The disadvantages of the mandrel include the uncertainty of the position of the workpiece, which excludes the possibility of adjustment work.
The working surface of the mandrel is made according to the quality of Is6. Mandrels of this type are used in the conditions of single and small-scale production.
Shown here is a mandrel onto which the workpiece is fitted with an interference fit. Using the thrust washer rings when attaching, the workpiece is precisely oriented along the length of the mandrel. If you make an annular undercut on the mandrel, pos. 1, then you can cut both ends of the workpiece. The neck, pos. 2, is a guide, it serves for free positioning of the workpiece by hand, the centering accuracy on a current mandrel is 0.005 - 0.01 mm.
The workpiece is placed on such a mandrel with a gap. The position of the workpiece along the length is determined by the flange of the mandrel; its turning is prevented by tightening the nut or key (if there is a keyway on the workpiece). For these mandrels, it is recommended to process the base surfaces of the workpiece according to the H7 quality. Centering accuracy depends on the gap and usually does not exceed 0.02-0.03 mm.
The material of the mandrels is steel 20X, with case hardening to a depth of 1.2-1.5 mm and Hardening HRc 55-60 units.
The working surface of the necks is ground to Re 0.65 cleanliness. The center slots are provided with chamfers or undercuts to protect against accidental damage. To transmit the moment at the end of the mandrel, a square, flats or a driving pin are provided.
Mandrels over 80 mm in diameter are made hollow for ease.
Prisms
A prism in devices is usually called a mounting part with a working surface in the form of a groove with an angle a equal to 60, 90, or 120, intended primarily for processing surfaces in a certain way located relative to the mounting cylindrical surface of the part.
The following types of prisms are used in machine tools:
wide - for installing parts with treated surfaces;
narrow - when installing parts on a rough basis, as well as suspending stepped shafts.
Large products are mounted on cast iron or welded prisms with replaceable steel plates on inclined surfaces
3.with pins on the mounting surface that have an irregular geometric shape.
According to the degree of mobility, the prisms are subdivided:
adjustable;
self-aligning.
The working surfaces and the base of the prism are ground. In prefabricated structures with two or more prisms used to mount one part, all prisms are ground together.
When assembling, prisms must be precisely set in a given position. Therefore, in addition to the fastening screws, two control pins are provided, which precisely, without a gap, fit both in the holes of the prism and in the holes of the housing on which they are installed.
The prisms are made of steel 20X7 with carburizing to a depth of 0.8-0.9 mm with a hardening of the working surface to a hardness of HRC 55-60 units. Large prisms are made of gray cast iron with screw-on hardened steel cheeks.
Devices coordinating position instrument
When performing individual machining operations (drilling, countersinking, boring), the rigidity of the cutting tool is insufficient. To eliminate the elastic squeezing of the tool relative to the workpiece, guide parts are used. They must be sufficiently accurate, durable and replaceable under certain conditions. The specified parts include jig bushings for drilling and boring attachments.
The design and dimensions of jig bushings for drilling are standardized.Permanent bushings are manufactured according to GOST 18429-73 without a collar, according to GOST 18430-73 with a collar, according to GOST 18431-73 replaceable, according to GOST 18432-73 quick-change, according to GOST 18434 intermediate bushings, according to GOST 18434 -73 intermediate bushings with collar, in accordance with GOST 12464-67 threaded bushings.
The use of jig bushings eliminates the marking operation, reduces the axis drift and the layout of the holes being machined. The accuracy of the bore diameter is increased by an average of 50% compared to machining without bushings.
For the manufacture of bushings when drilling with a diameter of up to 9 mm, 9XC steel is used, up to a diameter of 17 mm, U10 steel with a hardness up to 60 HRC units.
Permanent bushings are installed in the body or plate according to quality Is6 or according to quality h6.
The estimated service life of the jig bushings is 10.000 - 15000 drills. The average wear rate of the jig bushings when drilling holes with a diameter of 10-20 mm per 10 meters of track is 3-5 microns in the processing of gray cast iron of medium hardness, 4-6 microns of steel 40, and 1-2 microns of aluminum and its alloys.
Replaceable bushings are placed in constant g6 quality bushings and secured with a screw or strap. If the bushing is worn out, it is replaced at the workplace.
The presence of a through recess on the collar of the bushing next to the recess for the head of the fastening screw allows the bushing to be removed without unscrewing the fastening screw. This is achieved by turning the sleeve until the through-groove is against the head of the fastening screw.
The distance from the surface of the workpiece to be processed to the end of the sleeve, depending on the material being processed, is equal to 1/3 of the drill diameter for processing cast iron and other brittle materials to 1 drill diameter for processing steel.
Special jig bushings
They are used for machining holes in workpieces with complex configurations and hard-to-reach places, as well as for closely spaced holes.
Conductor plates
Sometimes jig bushings are placed directly in the cast or welded body of the fixture. This achieves a high machining accuracy in such a device, since the accuracy in this case depends on the accuracy of manufacturing the sleeves and on the accuracy of machining the holes for them. However, in order to simplify and reduce the cost of the manufacturing process of the device, it is advisable to make the plate separately from the body and fasten it to the body with screws. In order in this case to ensure the exact position of the plate on the body, in addition to the screws, dowel pins are used. Such plates are called permanent.
Permanent slabs sometimes create inconvenience when installing and removing the workpiece to be processed. Therefore, hinged (folding) plates are often used instead of permanent plates. At one end of such a plate, a hole is drilled for an axis about which the plate can be rotated to a position allowing easy access to the workpiece to be machined. This axis also serves as a support for the
ductor stove. At the second end of the plate, a slot is made for a hinged screw, with which the plate is pressed against the mounting elements fixed on the body near the hinged screw. This type of plate is characterized by reduced accuracy due to the presence of a movable joint.
In addition to folding plates, removable plates are used in production, which do not have a constant connection with the device body, are coordinated with the help of fingers precisely located on the body and are strengthened with quick-acting clamps. Such plates provide higher accuracy compared to folding plates and greater freedom of access to the workpieces being processed, but they take a long time to remove and install. To eliminate these disadvantages, in large-scale and mass production, such plates are suspended from the machine spindle like plates of multi-spindle heads and are therefore called suspended.
In mass and large-scale production, devices with lifting conductor plates are used, which are similar to suspended ones and differ from them only in that they are not permanently connected to the machine spindle and, on the contrary, are permanently connected to the device body. Thus, the device with a lifting plate can be used on any machine for both single-spindle and multi-spindle drilling. Typically, lifting slabs are characteristic of high-speed rock jigs.
Since bushings are installed in the jig plates, which serve to guide the cutting tool during operation, and the accuracy of processing depends on the accuracy of this direction, then when designing the plates, it is necessary to provide for sufficient rigidity. The thickness of the plates is determined by the height of the jig bush and is in the range of 15-3 mm. For high bushings on the plate, local thickening is provided. The stiffness of the slab is achieved by means of ribs cast in one piece with the slab or welded to it.
Calculation of the bushing diameter
Mating of the working part of drills, countersinks and rough reamers is performed according to the F7 quality in the shaft system.
Finish sweeps for G6 quality in the same system.
The largest limiting diameter of the working part of the cutting tool is taken as the nominal mating diameter.
Let's consider an example:
Reamer 18 +0012 Hole deviations in the shaft system by quality Gl + + lf 0 5 6
Add the upper and lower deviation of the required fit to the upper deviation of the tool. Then the diameter of the jig will be equal to N 18 JJ; JJJ
Quality F7 and G7 between the bore of the bushing and the cutting tool are taken to compensate for the expansion of the tool during the cutting process.
To increase the accuracy, it is possible to perform pairing according to the H7 quality, but in this case it is necessary to eliminate the heating of the tool and its jamming in the sleeve.
Installations for cutters
Installations for cutters are used to coordinate the relative position of the cutter and the workpiece before starting machining, when processing workpieces on tuned machines to automatically obtain dimensions.
By design, the units are divided into high-rise, corner and end units.
To pass the teeth of the cutter, which, with absolute fine tuning, can touch the end of the installation and damage its surface, the installation is located in the device below the surface to be processed by 1 -3mm, therefore, in order for the cutter to be at the level of the processed surface during processing, a probe with a thickness is laid between the surfaces of the installation and the cutter 1 to 5mm
The installation of the cutter according to the installation ensures the accuracy of the corresponding size of the part according to the accuracy quality.
The material for the manufacture of installations and probes is U7A and 20X steel with heat treatment of the working surface for all installations HRC 55-60 units.
Clamping elements of fixtures
Clamping elements hold the workpiece workpiece from displacement and vibrations arising under the action of cutting forces.
Clamping element classification
Clamping elements of devices are divided into simple and combined, i.e. consisting of two, three or more interlocked elements.
The simple ones include wedge, screw, eccentric, lever, lever-hinge, etc. - are called clamps.
Combined mechanisms are usually made as screw-lever, eccentric-lever, etc. and are called clamps. When simple or combined mechanisms are used in power-driven arrangements
(pneumatic or otherwise) they are called mechanisms - amplifiers. By the number of driven links, the mechanisms are divided: 1. single-link - clamping the workpiece at one point;
2. two-link - clamping two blanks or one blank at two points;
3. multi-link - clamping one workpiece at many points or several workpieces simultaneously with equal efforts. By the degree of automation:
1. manual - working with a screw, wedge and other devices;
2.mechanized, depending on the source of energy, are subdivided into
a) hydraulic,
b) pneumatic,
c) pneumohydraulic,
d) mechanohydraulic,
e) electrical,
f) magnetic,
g) electromagnetic,
h) vacuum.
3. automated, controlled from the working bodies of the machine. They are driven from the machine table, support, spindle and centrifugal forces of rotating masses.
Example: centrifugal-energy chucks for semi-automatic lathe.
Requirements for clamping devices
They must be reliable in operation, simple in design and easy to maintain; should not cause deformation of the workpieces to be fixed and damage to their surfaces; fixing and detaching the workpieces should be carried out with a minimum expenditure of effort and working time, especially when fixing several workpieces in multi-position fixtures, in addition, the clamping devices should not move the workpiece in the process of fixing it. Cutting forces should, if possible, be absorbed by the clamping devices. They must be perceived by the more rigid fixing elements of the fixtures. To improve machining accuracy, devices that provide a constant clamping force are preferred.
Let's make a small excursion into theoretical mechanics. Let's remember what is the coefficient of friction?
If a body with weight Q moves along a plane with a force P, then the reaction to a force P will be a force P 1 directed in the opposite direction, that is
Friction coefficient
Example: if f = 0.1; Q = 10 kg, then P = 1 kg.
The friction coefficient varies with the surface roughness.
Clamping force calculation method
Second case
The cutting force P z and the clamping force Q are directed to the same
In this case, Q => О
The cutting force P g and the clamping force Q are directed in opposite directions, then Q = k * P z
where k - safety factor k = 1.5 finishing k = 2.5 roughing.
Third case
The forces are directed mutually perpendicular. Cutting force P, counter-action to the friction force on the support (mounting) Qf 2 and the friction force at the clamping point Q * f 1, then Qf 1 + Qf 2 = k * P z
G 
def, and f 2 - sliding friction coefficients Fourth case
The workpiece is processed in a three-jaw chuck
In this direction, P, tends to move the workpiece relative to the cams.
Calculation of threaded clamping mechanismsFirst case 
Clamping with a flat head screw From the equilibrium condition 
where P is the effort on the handle, kg; Q - clamping force of the part, kg; R cp - average thread radius, mm;
R is the radius of the support end;
Lead angle of the thread helix;
Friction angle in threaded joint ~ 6; 
- self-braking condition; f is the coefficient of friction of the bolt on the part;
0.6 - coefficient taking into account the friction of the entire surface of the end. The moment P * L overcomes the moment of the clamping force Q, taking into account the frictional forces in the screw pair and at the end of the bolt.
Second case
■ Clamping with ball bolt
With increasing angles α and φ the effort P increases, because in this case, the direction of the force goes up the inclined plane of the thread.
Third case
This clamping method is used when machining bushings or discs on mandrels: lathes, dividing heads or rotary tables on milling machines, slotting machines or other machines, gear hobbing, gear shaping, radial drilling machines, etc. Some data on the reference:
Screw Ml6 with a spherical end with a handle length L = 190mm and a force P = 8kg, develops a force Q = 950 kg
Clamping with a screw M = 24 with a flat end at L = 310mm; P = 15kg; Q = 1550mm
Clamping with hexagon nut Ml 6 wrench L = 190mm; P = 10kg; Q = 700kg.
Any modern enterprise uses technological equipment. The result of production and the quality of products directly depends on what quality it has and on the timely equipping of all the necessary jobs with it. What is the reason for this? Reducing the time for performing manual operations allows you to reduce labor intensity, significantly increase reliability and accuracy during production finished products... Such technological equipment at the enterprise minimizes the release of defective products, simplifies the production process and increases labor productivity. It also forms the basis for multi-station production.
The production and design of tooling is a rather time-consuming process. Here it is necessary to constantly apply the most advanced and modern achievements of science and technology. Modern requirements that apply to the entire engineering field of activity require a better approach directly to production process... That is why the production of technological equipment is subdivided into several main stages:
- Coordination and signing of all necessary contracts for the supply of maintenance.
- Development of technological equipment.
- Its design.
- Modernization of products if necessary.
- Delivery and delivery of maintenance to the customer.
- Signing of all documents of acceptance.
- Technical support throughout the entire warranty period.
The production of tooling is carried out by highly qualified specialists in specially designed systems such as CAD, CAE and CAM. After it has been manufactured, the next very important stage is performed - the formation of a simulator for the manufacture of the part itself. This is done with the aim of performing a more detailed analysis of the structure at the design stage and checking its performance until the moment when it is embodied in metal product... It also makes it possible to develop special control programs for CNC machines. As a result, all these measures allow to significantly reduce the production time of high-quality maintenance.
Tool economy at the enterprise
This is an amalgamation of workshop and general production units, whose activities are based on timely and comprehensive provision of all the necessary types of technological equipment. The organizational forms, as well as the structure of this division of machine-building enterprises, are very diverse. This is determined by a number of technical and economic factors:
- design features of manufactured parts;
- volume of products manufactured;
- technological processes;
- the constancy of the nomenclature itself;
- the level of cooperation in the production of tooling together with other specialized companies.
The most important task of this farm is planning, manufacturing and control of technological equipment. It also includes determining the needs of the enterprise in its availability.
Technological equipment of the workplace
Workplace organization falls into three main categories: planning, equipment and services. Every production site must have everything necessary equipment, which allows you to efficiently and efficiently carry out all the planned work. It is also obliged to ensure safety and comfort during the performance of various technological operations, to free staff from heavy physical labor and to easily operate the equipment itself. Exactly the same requirements apply to technological equipment. These means of mandatory technological equipment of the workplace enable operators to perform their work efficiently and efficiently. The types and quantities of this equipment are determined based on the process maps themselves. They must comply with the nature of all work performed on a specific site and make it possible to make the most of all the available technological capabilities of the equipment.
In addition to all this, the technological equipment of the workplace should be convenient for use, guarantee minimum costs time during its installation and be safe for all working personnel. Such equipment in mechanical engineering includes:
- various sets of tools;
- devices for fixing and installing workpieces;
- control and measuring instruments;
- cutting tool;
- technical, reference and accounting documentation.
Technological equipment of lathes
This equipment plays a very significant role in the work of any metal processing enterprise. And this is no exaggeration at all. Indeed, at the present time in this industry there is simply a huge number of universal devices (several million) for the most diverse purposes. In order to make one part, on average, about ten such devices are used.
Technological equipment lathe allows you to significantly improve the quality of parts produced by the company and labor productivity. The most popular equipment for this type of machine is: scroll chuck, various bushings, tool holder, blade mechanisms, vices, milling attachments for a lathe, cutting tools, various auxiliary products and much more.
Thanks to this equipment, it is possible to carry out turning of products safely, with high level accuracy and performance. Due to the fact that during such work, the part itself needs to be rotated with its reliable fixation for turning in various speed modes, it is necessary to use standard sizes of equipment and various devices.
Technological accessories for CNC machines
There are special requirements for this equipment in metalworking industries. This refers to the high level of product manufacturing accuracy compared to conventional machines. On CNC machines, the programming of all movements is clearly specified in the coordinates of the equipment itself. As a result, it becomes necessary to accurately position the tool itself and the workpiece in the fixture. In the machining cycle itself, quite a lot of time is spent on resetting the part. That is why it is necessary to use special quick-clamping technological equipment, which is equipped with a pneumatic and hydraulic drive. Also, in order to minimize the time of technological preparation, standardized devices or their layout should be used.
Foundry technological equipment
In order to manufacture various casting molds, it is necessary to use specially designed devices used at the enterprise in various technological casting processes. Part of such a casting tooling, necessary for the formation of a casting mold, constitutes a molding kit. This includes sub-model slabs, models, flasks, core boxes and more. These models are universal devices that are designed to obtain cavity impressions from the molding sand, corresponding to the external configuration of the casting itself. All its holes and contours are formed using rods, which are mounted in the forms themselves during their assembly.
Metal models are more durable, have a high level of accuracy, and a clean work surface. In most cases, they are made from aluminum, which has a low density, does not oxidize and is well cut.
Flasks are pretty strong metal frames of any shape. They are intended for the manufacture of casting molds from molding sands. Most often they are made from steel, gray cast iron and aluminum alloys. They can also be welded, cast or assembled from separate cast parts. The walls of this design are made with small holes. This allows you to reduce its weight, remove excess gases and improve the bonding of the molding sand to the flask itself. The connection of this design is carried out using specially designed pins, as well as centering holes located in the tides.
Exhibition "Metalworking6"
The Central Exhibition Complex of Moscow Expocentre Fairgrounds invites everyone to visit a specialized exhibition of an international scale. It will exhibit equipment and various instruments used in the metalworking industry. There will also be presented modern technological equipment for installation processes. This event has not been held for the first time (since 1984) and annually brings together leading specialists and representatives of industries from all over the world in one place. This year, it is expected that the Metalloobrabotka exhibition will be attended by about 1000 companies from different countries the world. They will present to potential target audience modern equipment, as well as advanced technologies and achievements in the industry.
At a special forum, the most pressing issues in metal processing at the present time, as well as the industry's prospects for the near future, will be considered. By visiting conferences, congresses, symposia, round tables or seminars at the exhibition, you can learn in more detail about what technological equipment is present in machine-building production at the present time, what awaits the industry in the near future, and much more.
0It is difficult to overestimate the importance of technological equipment in the organization of complex mechanized mechanical workshops. The technical level of the tooling of metal-cutting machines determines the efficiency of the technological operation, the processing productivity and the accuracy of the parts obtained to the same extent as the quality of the machines themselves. Technological equipment creates conditions for the transition from a sequential method of processing to parallel and parallel-serial, and its technical level predetermines the cost of auxiliary time for the removal and installation of the part.
However, if the benefits of using special equipment in large-scale and mass production there is no doubt, the widespread use of special equipment in small-scale and batch production can cause unjustified losses. And not so much because of the big material costs for the development and manufacture of tooling, which is not unimportant, how much due to the excessive delay in the preparation of production. This does not mean, of course, that small-scale production should not be involved in the technological equipment of machine tools. The absence of tooling increases the installation time of the part several times and affects the quality of the products. Even when switching to machines with numerical program management it is necessary to develop mounting devices for fixing parts. But work in this direction has its own characteristics.
Technological equipment for small-scale production should be carried out by:
1) development of universal technological equipment and machine accessories;
2) the use of reversible tooling designs that allow assembling special devices from unified elements or units and disassembling them into elements;
3) the use of specialized, including readjustable devices for processing structurally-like parts that are in a certain size range;
Rice. 57. Screw clamps for machine slots
4) application of interchangeable adjustments to universal and specialized devices for basing the workpiece;
5) the use of universal locating and clamping elements (mechanical, pneumatic, hydraulic, etc.), which allow fixing the part directly on the machine table.
Consider now the series constructive solutions on technological equipment of metal-cutting machines.
Universal clamping elements. In single and small-scale production, the processing of parts on milling, boring, planing machines is usually carried out without setting devices, and the parts are fastened with screw clamps different types, sizes and designs. At the same time, the difficulty lies in the fact that the clamping surface of the part has different heights, the clutch must be "built up" by replacing its screw and support base, the time for fixing the part increases. There are a number of designs of universal screw clamps, allowing within certain limits to change the height of the clamp without replacing the clamps.
In fig. 57, and in table. 11 shows screw clamps for machine grooves in four sizes: a = 12, 14, 16 and 18 mm. Clamp bodies contain a clamping screw and an adjustable support bar. The adjustment range of the clamps for the height of the clamping surface is shown in table. 11: 40 mm (55-95) to 100 mm (400-500).
In fig. 57, b shows screw clamps with a support "ladder" for table slots a - 12, 14, 16 mm. This design of clamps also has a wide range of clamping heights: depending on the standard size, clamps allow you to clamp parts with a difference in height of 0-45, 15-45, 30-75, 60-135 mm, etc. (Table 12).
When processing parts such as plates, strips, rails, it is impossible to use a clamp only from above, since this surface is to be processed, they cannot be clamped in a vice because of the size of the parts; in this case, it is advisable to use universal elements, in which the main force is directed in the horizontal plane in order to press the workpiece to the stops.
The design and dimensions of these clamps are varied, they are selected depending on the dimensions of the grooves of the machine table and
Rice. 58. Universal clamps: a and b - horizontal; c - combined
Workpiece heights. Some of these clamps create a force not only in the horizontal, but also in the vertical plane, pressing the workpiece to the machine table (Fig. 58, a-c and tables 13-15).
All types of screw clamps and clamps, with all their versatility, have two main disadvantages: the need to apply significant physical effort to secure and release the part; large losses of auxiliary time for setting, clamping and removing the part.
The mechanization of universal clamping elements proceeds mainly along the way of using hydraulic and mechanohydraulic clamps. Drive accumulators or pneumohydraulic boosters supplying oil for the clamps under a pressure of 60-160 kgf / cm 2 are located either outside the machine and connected to the clamping hydraulic cylinders with flexible hoses, or - for large and heavy machines - directly on the machine table.
Mechanical hydraulic clamps are usually understood as small manual hydraulic pumps for clamping parts, installed on the machine table, operated by a handle or a key.
Hydraulic clamps have built-in hydraulic cylinders with a diameter of 40 and 50 mm (Fig. 59, a and Table 16) and operate at a pressure of 100 kgf / cm 2. The clamps are made retractable, which makes it easy to remove the workpiece. The design of these clamps has a relatively small range of clamping heights (45-60 mm), and an adjustable hydraulic clamp is more versatile (Fig. 59, b and Table 16). In this case, the clamping range is determined by the length of the screw on which the clamp and the hydraulic cylinder are located. Height adjustment of the clamping position is carried out by means of nuts (lower, supporting the spring, and upper), as well as by repositioning the stepped support.
To clamp the parts in the horizontal plane, hydraulic clamps can be used (Fig. 59, c). The body of the clamp is based in the slot of the table and at the same time serves as a support for the workpiece to be clamped. The clamping force is determined by the diameter of the hydraulic cylinder (40, 50 and 60 mm) and is respectively 920, 1460 and 2070 kgf.
Rice. 59. Hydraulic clamps:
a - with a built-in cylinder: b - adjustable in height of the clamp; в - horizontal; g - articulated; d - a clamp with a mechanohydraulic clamp; e - mechanohydraulic nut
A wide range of clamping allows the implementation of hinged hydraulic clamps (Fig. 59, d), developed by VPTYAZHMASH. The clamp is installed and fixed in the T-shaped slots of the table. The clamping force is transferred to the gripper from the articulated double-acting cylinder. The working pressure of the oil in the cylinder is 50 kgf / cm 2. Height adjustment of the stick in the range from 40 to 220 mm is carried out by rotating the knurled nut.
When fixing parts on heavy metal-cutting machines, the use of group hydraulic units with wiring to individual clamps causes a pile of hoses and complicates the maintenance of the machine. In these cases, it is advisable to use mechanohydraulic devices operated by a handle or a key and having a closed hydraulic system... A relatively small force (2-10 kgf) applied by the worker on the key handle is amplified hundreds of times and reaches 2000-10,000 kgf at the grip.
In fig. 59, d shows a clamp with a mechanohydraulic clamp for fixing parts on the tables of heavy longitudinal milling, boring and planing machines. When the screws are rotated with a socket wrench with a handle length of 150 mm and a force of 10 kgf, the hydraulic cylinder creates a force up to 7500 kgf at the grip. Clamping device piston stroke 10 mm. The mechanohydraulic nut (Fig. 59, e) is screwed manually onto the screw until the clamp contacts the part to be clamped. When the M10 screw is rotated with a socket wrench with a force of 2 kgf, the closed hydraulic system of the nut creates a clamping force of up to 3750 kgf.
Mechanohydraulic devices can also be used to supply hydraulic clamps of special devices.
Multipurpose prefabricated tooling. With a wide range of standard parts, universal assembly fixtures (USP) make it possible to replace up to 70-80% of special tooling, which not only reduces costs, but also shortens the time for technological preparation of production. USP is effectively used in single and small-scale production. The main disadvantage was the lack of mechanized (hydraulic, pneumatic, etc.) clamps in their designs. This increased the time for the installation and removal of the part, and in the conditions of serial production, factories often used special, albeit more expensive, equipment. In recent years, a number of additional USP elements have been created, which make it possible to mechanize the clamping of a part.
For various branches of mechanical engineering, three standard sizes of sets of parts for USP have been developed, standardized and manufactured, which differ in the diameter of the fastener, the width of the grooves and overall dimensions main elements.
1. A set of parts for universal assembly devices with a groove width of 8 mm for processing small dimensions (220x120x100 mm). The design and dimensions of USP-8 elements are regulated by GOST 14582-69-GOST 14607-69.
2. A set of parts for universal assembly devices with a groove width of 12 mm for processing medium-sized parts
(700x400x200 mm). The design and dimensions of USP-12 elements are regulated by GOST 15436-70-GOST 15465-70. There are two versions of this kit: a starter kit for low-power plants with a small amount of machining and an extended kit for plants with a large amount of machining.
3. A set of parts for universal assemblies with a groove width of 16 mm for processing large parts (2500 X X2500X 1000 mm). It is used in heavy engineering plants. The design and dimensions of USP-16 elements are regulated by GOST 15636-70-GOST 15761-70.
A number of USP-8, USP-12, USP-16 elements and elements of a universal prefabricated readjustable equipment of a different type, for example, universal prefabricated overhead conductors, readjustable mechanized units, etc., are interchangeable. This expands the scope of the fixtures.
The main data of the USG1-8, USP-12 and USP-16 kits are given in table. 17 (based on materials from MGKTB Soyuztekhosnastka). Further development of USP is the system of readjustable universal assembly devices (PUSP), developed by MGKTB Soyuztekhosnastka. The PUSP set is a set of non-separable assemblies, including mechanized high-speed clamps, from which various accessories for milling, boring, planing, drilling and other works are assembled.
The PUSP elements allow the installation and fastening of the workpieces directly on the machine table. The PUSP kit includes base and clamping units and pneumohydraulic drives. The basic non-separable units include a hydraulic vise, a plate with a pneumatic drive, hydraulic units, which are a plate with several hydraulic cylinders. The clamping elements are hydraulic cylinders, eccentric clamps, universal clamps and parts for their installation and fastening in various positions. For quick clamping of workpieces with low cutting forces, eccentric clamps are also used. In the PUSP set, preference is given to non-separable assemblies, which accelerate the assembly process and changeover of layouts, reduce the number of joints, which increases the rigidity of the fixture and processing accuracy.
The drive of the hydraulic elements of the PUSP is carried out from a pneumatic hydraulic booster, which converts the compressed air pressure (4-6 kgf / cm 2) into a high (100-150 kgf / cm 2) oil pressure, which makes it possible to obtain the necessary clamping forces with a relatively small size hydraulic cylinders.
The connecting dimensions of the basic parts of the main units of the PUSP are interconnected with the existing sets of universal-assembly devices with a groove of 12 and 16 mm (USP-12, USP-16), which makes it possible to expand the possibility of using USP by assembling high-speed mechanized devices for processing large batches of parts. Such devices can replace a number of special devices in mass production and group processing of parts, where USP was usually not used.
PUSP expand the technological capabilities of USP and have a number of advantages that allow them to compete with high-speed mechanized special or permanent group devices used in mass production.
The time for the initial assembly of devices and their changeover is reduced due to the use of non-separable units. Using non-separable assemblies during the transition from processing one part to another, you can replace the assembly with the readjustment of the already assembled device, which requires 3-4 times less time.
The presence of the PUSP allows the use of a group processing method with frequent changes in production facilities and a wide range of processed parts, since from the PUSP set, group devices can be assembled, which, after the end of the work, are readjusted for processing another group of parts.
Universal machine tooling. Small-scale production for drilling holes in cylindrical parts
Rice. 60. Universal jig for drilling parts clamped in a three-jaw chuck:
a - with cantilever fastening; b - with additional support from the center; в - from the side of the end
with an accuracy of the order of 0.1 mm - it is advisable to use universal conductors. The Schmidt-Costa universal conductor, shown in fig. 60, a (Table 18), allows you to fix the part in a three-jaw chuck mounted on a dividing faceplate. Adjustable bar with replaceable jig bush moves vertically on two racks.
This jig allows you to drill, countersink and thread holes located on the outer surfaces of cylindrical parts.
In fig. 60, b shows a similar jig with fixing parts in a cartridge with support back center.
For processing at the ends of cylindrical parts such as flanges, covers, glasses, a universal conductor of the same company is used (Fig. 60, c). Dividing plate of the conductor, carrying three-jaw chuck, allows you to obtain an angular arrangement of holes, and a movable bar with a jig sleeve provides the necessary offset of the holes from the center of the part.
With an increase in the scale of production, as well as for precise work, the above types of universal conductors are inferior to rock conductors with special adjustments, as well as the simplest special conductors (for example, overhead). It is advisable to combine the use of special conductors with a universal device for securing them. In fig. 61 shows a stationary table 1 (pedestal) with a pneumatic clamp 2 to a radial drilling machine. Parts or conductors for drilling holes are attached to the table on plate 3. The clamping force is transmitted from the pneumatic piston 4 through the threaded coupling 5, connected to the piston rod and the screw 6. With a network pressure of 5 kgf / cm 2, the force developed by the pneumatic cylinder reaches 1500 kgf.
In fig. 62 shows a specialized jig for drilling parts such as slats, installed on a table with a pneumatic clamp. The device consists of a base
Rice. 61. Table with a pneumatic clamp for a radial drilling machine (pneumatic column)
part 1, fixed on the table B (pedestal), and replaceable adjustments - jig plates 2. The workpieces to be processed are installed on the support strips 3 and pressed against the strips 4 with a clamp 5. The clamping force is transferred to the clamp 5 from the pneumatic clamping of the cabinet through the pin 6, lever 7 and bolt 8.
The most common type of universal machine tooling are rotary indexing tables and columns with vertical and horizontal axis of rotation. They are produced in various sizes and types, with varying degrees of dividing accuracy, with manual, pneumatic, hydraulic and electric drive, with an automated and non-automated cycle of work. Universal indexing tables and stands are used to perform various operations on vertical and radial drilling, milling and boring machines, and also built into the structure of modular machines (especially small sizes). The most promising indexing tables, in which division and fixation are carried out by two flat gear wheels (firm "Fibro"), providing a division accuracy of ± 3 ". Indexing tables with a pneumatic drive and a ratchet mechanism of rotation and fixation, similar to the table shown in Fig. 63. This table can work in an automatic cycle.
Rice. 62. Specialized setting device for drilling parts such as strips on a table with pneumatic clamp
Rice. 63. Dividing table Ø 250 mm with pneumatic drive of the dividing mechanism
Rice. 64. Dividing rack with faceplate 800X800 mm
For drilling and boring works performed on radial drilling machines, in devices with a tool direction, rotary indexing posts developed by Orgstankinprom with a horizontal axis of rotation and faceplate dimensions of 500x500, 800x800 and 1200x1200 mm are widespread. Racks are made with one- and two-support, which allows you to install on them cantilever (or with support) various clamping devices or workpieces. The rotary part of the rack is driven by an electric motor through a gearbox; the stand is automatically locked after 90 ° of rotation. The faceplate can be stopped in any other position and manually locked. The dividing accuracy with automatic fixing of the faceplate is 3 ". This relatively low accuracy is compensated by the fact that the tool, having freedom in a quick-change chuck, is guided along the bushings of the device.
In fig. 64 shows general form dividing rack with faceplate 800x800 mm. The stand is controlled by a foot pedal. The rack is mounted at the pit, which allows the rotation of parts with dimensions exceeding the dimensions of the faceplate. The main dimensions of the indexing racks are given in table. nineteen.
Specialized adjustment devices. The unification of the geometric elements of parts creates conditions at the enterprise for combining structurally similar parts into groups that have the same type and differ only in size or additional elements (holes, grooves, bald
us, etc.). At the same time, such advantages of special adjustment devices as accuracy of locating and quick installation of a part are preserved, and the possibility of changeover to a group of structurally similar parts is added. Specialized setting devices are used for milling, drilling, boring and other works. In fig. 65 shows a specialized setting device for milling the planes of parts such as strips and wedges on vertical milling machines. The device consists of a base part 1 (with built-in hydraulic clamps) and replaceable set-ups 2. An intermediate plate 3, used to reduce the height of the set-ups, is installed on the upper plane of the base part along the keys 4 and fixed with screws 5, 6 and nuts 7. Simultaneous fastening of two processed parts is carried out by four interlocked clamps 8 and 9. Interchangeable inserts 10 and 11 are used to reduce the clamping size. The clamping force is transmitted to the clamps from the single-acting two-piston hydraulic cylinders 12. The device allows processing parts with a length of 100 to 800 mm, a width of 50 to 80 mm and a height (thickness) of 18 to 50 mm. In fig. 66, a-c shows examples of replaceable adjustments to the device shown in Fig. 65.
A specialized tool for milling flanges and covers is shown in Fig. 67. The device consists of a base part 1 with a built-in hydraulic clamp and replaceable adjustments 2 installed on the upper plane. The fixing of the workpieces is carried out by the clamp 3,
Rice. 65. Specialized adjustment device with built-in hydraulic clamps for milling parts such as strips and wedges
Rice. 66. Replaceable settings for the device for milling strips and wedges (crosses show the surface to be machined)
Rice. 67. Specialized tool for milling flanges (crosses show the surface to be machined)
transmitting the clamping force from the piston of a single-acting hydraulic cylinder 4 through an adjustable bolt 5. Depending on the height of the workpieces being processed, the vertical position of the stick is adjusted by bolts 6 and 5. Through the union 7, fluid is supplied to the cylinder.
Changeable settings for the device allow you to process parts with a diameter of 50 to 100 mm at a height of 15 to 60 mm.
As an example of a specialized device that does not require replaceable adjustments, Fig. 68 shows a device for cutting parts such as strips. The device consists of a base part 1 with built-in clamps and adjustable setting elements: strips 2, 3 and a stop 4. The device is readjusted by rearranging the strips 2 and 3 in the grooves of the housing 1, as well as by rearranging and adjusting the position of the stop 4, which is moved along the groove of the strip 5. The parts to be cut are installed on the projections of strips 2, 3 and strips 5, 6.
The clamping force is transmitted to the clamps 7 from the double-acting hydraulic cylinder 8 through the lever 9, the bar 10 and the pins 11.
To drill a group of flange-type parts, a specialized adjustment device is used, shown in Fig. 69. The device consists of a plate 1, a rotary part 2 and replaceable adjustments 3. The adjustments are designed individually for each workpiece. They consist of a support part for centering the workpiece and an overhead jig. The adjustments are installed on the upper plane of the device along the cylindrical shank of the plunger 4. When the handle 5 is turned, the eccentric shaft 6 through the plunger 4 and the rod 7 fixes the workpiece 9 together with the adjustment on the device body.
The jig is fixed on the table of the vertical drilling machine, and the part is brought to the spindle axis by the handle 8, which moves the rotary part along with the adjustment.
The dimensions of the parts processed with this device should not exceed 200 mm in the maximum diameter of the flange; along the flange protrusion on the other side, they should have a diameter of at least 30 mm with a total thickness of the part not exceeding 120 mm.
Precision expanding mandrels. When processing parts such as bodies of revolution with precise central holes (gears, bushings, rings, etc.), there are two fundamentally different directions in the construction of the technological process: final processing of the external and internal surfaces of the part in one setup or processing of one of the surfaces on the base the finished other surface. Since in most cases finishing processing in one setting of the outer and inner surfaces is not possible, the equipment for accurate centering of the part during finishing is of great importance. The greatest accuracy is achieved when the part is mounted on a rigid mandrel with a taper of 1: 100, which is used in tool shops and repair shops.
Rice. 68. Specialized device for cutting parts such as strips (the cutting place is shown with crosses)
Rice. 68 (continued)
Rice. 69. Specialized tool for drilling flange-type parts
However, when the part is mounted on a tapered mandrel, a constant axial position of the part is not ensured. In addition, the installation and removal of the part on such mandrels is performed manually. For these reasons, the use of expanding mandrels is most promising, which have a number of advantages over rigid ones: the speed of removal and installation of the part during the automation of this process, the constancy of the axial position of the parts, the possibility of basing on the hole made according to the 3rd-4th accuracy classes.
Precision machine tools include mandrels with corrugated bushings for machining parts such as rings, bushings and sleeves. The centering clamping element of the mandrel (corrugated sleeve) is loaded with an axial compressive force and deforms. Wherein inner diameter the corrugated sleeve decreases and the outer one increases. The inner surface of the corrugated sleeve is precisely centered and fixed on the mandrel shaft, and the outer surface precisely centers and fixes the workpiece.
The amount of axial compressive load that must be applied to the corrugated bushing to center and securely hold the workpiece depends on the size of the bushing. For example, for a sleeve with dimensions D = 20 mm and L = 20 mm, this load is Q = 220 kgf; at D = 50 mm and L = 30 mm Q = 600 kgf; with D = = 100 mm and L = 50 mm Q = 1600 kgf.
Experimental studies and industrial observations show that when using mandrels with corrugated bushings, the radial runout of the machined outer surfaces of the workpieces can be maintained within the 2-4th degrees of accuracy in accordance with GOST 10356-63. Thus, corrugated arbors are the most accurate among modern self-centering arbors. clamping devices... In terms of the achieved centering accuracy of the workpieces, only stepped cylindrical mandrels are similar to them. However, when using stepped cylindrical mandrels, selective selection of blanks is inevitable, while mandrels with corrugated bushings allow processing blanks with deviations in the diametrical dimensions of the base holes within 1-2 accuracy classes (depending on the nominal value of this diameter).
Material for the manufacture of corrugated bushings - steel grade 60S2HFA according to GOST 14959-69, hardness after hardening HRC 42-46. Steel grades 60С2А and 65С2ВА are allowed for bushings with dimensions D = 19.99 ÷ 39.98 mm and D = 84.968 ÷ 94.968 mm; steels of grades 60S2A, 65S2VA, 50KhFA and 60S2 for bushings with dimensions D = 44.98 ÷ 54.97 and D = 99.968 mm; steels of grades 60S2A, 65S2VA, 50KhFA, 60S2, 55S2, 55GS and 65G for bushings with dimensions D = 59.07 ÷ 79.97 mm.
To ensure high accuracy of centering of workpieces, the mandrel with corrugated bushings must be manufactured very accurately.
Rice. 70. Basic technical requirements for corrugated bushings for precision mandrels
Basic requirements for dimensional and geometric parameters bushings are shown in fig. 70. The runout of the mandrel shaft should be maintained within the 1-2 nd degrees of accuracy in accordance with GOST 10356-63. During operation, mandrels with corrugated bushings wear out, which reduces the accuracy of centering the workpieces by an average of 3-5 microns for every 25-30 thousand fixings.
The use of mandrels with corrugated bushings, along with the height of the centering accuracy, makes it possible to obtain a high roundness of the machined surfaces of parts, including thin-walled ones. This is due to the fact that the force of fixing the workpiece by corrugated bushings is evenly distributed around the circumference of the base hole. Deformations of workpieces under the action of such forces are uniform and do not cause out-of-roundness. In this respect, mandrels with corrugated bushings compare favorably with cam, collet and wedge-plunger devices with concentrated clamping forces.
In real workpieces, reference holes are always non-circular. When using mandrels with corrugated bushings, the out-of-roundness of the base holes of the workpieces is transferred to the machined outer surface... However, the out-of-roundness of the machined surface can be reduced by about 2.5 times in comparison with the out-of-roundness of the base hole.
Rice. 71. Mandrels with corrugated bushings: a - center; b - flanged; c - cantilever (Morse taper 1)
Mandrels with corrugated bushings ensure the transmission of torque and shear forces during finishing operations, have relatively small diametrical dimensions and simple design, can be made on universal machine tools. When using pneumatic, hydraulic or electromechanical clamping, the mandrels are fast acting. Mandrels with corrugated bushings can have a center, flanged or cantilever design (Fig. 71) and serve to clamp workpieces with solid, intermittent, stepped or blind base holes.
Corrugated bushings should be deformed only within the elastic deformation range. Therefore, the greatest stresses arising in the sleeve during the operation of the mandrel should be less than the yield stress σ 0.2 of its material. This condition is ensured by using appropriate materials and heat treatment bushings.
Calculations of the geometric, power and strength parameters of corrugated bushings are carried out using the methods of the applied theory of elasticity. The calculation methodology was developed at the Moscow State Technical University. N.E.Bauman tech. Sciences A. A. Shatilov.
One of the most accurate expanding mandrels is the range of mandrels of the specialized firm "Tobler" (France), some of which are shown in Fig. 72. A cantilever expanding mandrel with a collet expanding using a wrench (Fig. 72, a) provides a centering accuracy of 0.02 mm.
The center expanding mandrel (Fig. 72, b) is used in individual production. The two-sided arrangement of the grooves in the collet provides a spreading range of up to 4-5 mm with a centering accuracy of 0.02-0.03 mm.
At cantilever mandrels (Fig. 72, a and d), clamping is carried out either with a round nut (Fig. 72, c), or with a rod connected to a hydraulic or pneumatic cylinder.
The collet chuck (Fig. 72, e) has retractable end stops, allowing you to make groove of both ends of the part in one installation of the part.
When cutting a package of several gears on hobbing machines, the installation of parts is usually carried out on cylindrical mandrels, which leads to inaccurate centering of individual parts in the package. Tobler has created an expanding mandrel for gear hobbing machines (Fig. 73), where each of the parts to be clamped is centered by a separate expanding collet. For particularly precise operations, as well as for the control of precision parts, expanding mandrels with hydroplast (the design is patented by Tobler) can be used, providing centering accuracy of 0.002-0.004 mm.
End driver chucks. For turning parts such as shafts, it is advisable to use end driver chucks that replace clamps and cam driver chucks. The use of chucks of this type makes it possible to grind all external surfaces in one installation. stepped shaft, which is especially effective when machining shafts on multi-support CNC lathes, including those with a working movement of the tool in the direction both to the headstock and to the tailstock (Fig. 74, a). End drive chucks can have different designs: for installation in the spindle cone and for mounting on a flange (Fig. 74, b and c).
When installing the part on the center of the chuck and pressing it with the tailstock, the floating center is displaced to the stop of the end of the part in the driving pins. To compensate for possible misalignment of the end face of the part, the driving pins with their rear end rest on a damping gasket.
The torque transmitted by the end driver chuck depends on the ratio of the clamping diameter of the driver to largest diameter details, which must be at least 1: 2; downforce generated by the rear center; the processed material and its mechanical properties; direction of feed movement (when feeding from the spindle to the tailstock, the calculated downforce must be doubled).
Rice. 72. Precision expanding mandrels from Tobler (France):
a - cantilever mandrel with a key clamp; b - center mandrel; c - cantilever mandrel with free hand release; d - power chuck with flange mount and expanding collet; d - powered chuck with removable stops
Rice. 73. Expanding mandrel from Tobler (France) for gear-cutting machines
For reliable work of driver chucks, it is necessary that the misalignment of the end face of the parts on the circumference of the leashes does not exceed 0.1 mm (compensated by a damper), therefore, it is better to grind or counterbore the ends of the workpieces, rather than milling. Sharpening of driving pins should be carried out only as a set - by one size, with fluctuations in length no more than 0.01-0.02 mm.
Multi-size collet chucks. Clamping collets for turret lathes, lathes and automatic revolving machines, as a rule, allow fluctuations in the diameter of the bar to be fixed no more than 0.1-0.2 mm. For this reason, machines of this type must have a large range of collet chucks that can be replaced when setting up the machine. In the conditions of small-scale production, it is effective to use multi-size clamping collets of the type of collets from Pratt-Barnerd (England).
Rice. 74. Schmid-Costa drive-end chucks:
a - a diagram of turning the shaft in one installation using a face driver chuck; b - the design of the chuck installed at the end of the spindle; c - the design of the driver chuck with flange mounting
Collets of this company differ from the known types of clamping collets: the collet body does not deform during operation, and the clamping is carried out by six movable liners having radial movement in the collet grooves. Each standard size of such a collet, without replacing the liners, provides a clamping of a bar or piece workpiece in the diameter range of 2.5-3.0 mm. So, for example, the first collet size provides a clamping of a bar Ø 1.6-4.8 mm, the following collet sizes cover diameters 3.2-6.4; 6.4-9.5; 9.5-12.7; 12.7-15.9 mm, etc. The use of multi-size collets on revolving machines, on single-spindle bar automatic machines, on lathes and operating machines performing the second operations, several times reduces the set of clamping collets and reduces the time for equipment changeover. In some cases, the use of multi-size clamping collets allows you to switch to the processing of hot-rolled material instead of calibrated one.
Used literature: "Complex mechanization and automation in mechanical shops" authors: Zhdanovich V.F., Gai LB ..
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