RU2086393C1 - Method for reducing internal stress in shaft-type parts - Google Patents

Abstract

FIELD: surface treatment of parts for reducing residual stresses. SUBSTANCE: prior to finishing a part, it is mounted in means of rotation in cantilever and is brought in contact with sliding support. In the course of rotation of the part force is applied to its cantilever portion from the side opposite to the sliding support relative to the longitudinal axis of the part. The applied force shall be directed normally to the part axis and is displaced relative to the sliding support in the direction of free end of the part. In the course of treatment the direction of part rotation is periodically changed with simultaneous synchronous movement of the sliding support and point of force application in one direction, which is also periodically changed depending on the sense of the part rotation. Magnitude of compression, tensile and torsional stresses arising in the part do not exceed actual elasticity limit stress in the material of the part being treated. EFFECT: improved quality of parts. 3 cl, 2 dwg

Description

 The invention relates to mechanical engineering technology, namely to the processing of parts such as shafts (shafts, screws, rods, spindles).

 The aim of the invention is to reduce the leash of shafts, screws, rods, spindles after machining, after heat treatment and after the application of operational loads to them by reducing internal stresses in them.

 In FIG. 1 is a graphical method and device for its implementation, where pos. 1 indicates the workpiece, pos. 2 chuck of the lathe, pos. 3 the tool holder of the lathe, item 4 body of the intermediate support, item 5 case of the pressure part of the device installed and secured in the tool holder 3. Figure 2 shows a step section along aa of Figure 1.

 The arrows indicate the necessary tuning and working movements of the parts of the device relative to each other and the workpiece 1.

 The way to reduce internal stresses in parts such as shafts (shafts, screws, rods, spindles) on the walls of the turning type has the difference in that to the fixed cantilever in the chuck 2 of the machine and rotated first on one side and then on the other side of the part 1, supported by the outer the surfaces of its cantilever part onto solid wear-resistant inserts 6 of the device part, called the intermediate support 4, mounted and fixed on the support of the machine, which are self-mounted relative to the surface of the part; to the outer surface of the cantilever part of the part 1 from the predominantly diametrically opposite side from the action on the part 1 of the inserts 6 of the intermediate support and with a longitudinal displacement relative to the part from the support 4, the load P, which communicates the part 1 through force contact and friction forces to the wedge prismatic gap formed by solid wear-resistant liners 7 of the loading part 5 of the device, bending, torsion, tension and compression forces while synchronously moving the supporting and loading parts of the device and their liners 6 and 7 in ol axis of the workpiece 1.

 A device for reducing internal stresses in parts such as shafts (shafts, screws, rods, spindles) by treating (dressing) the surfaces of the parts by force contact on turning machines consists of an intermediate support part 4, the casing of which is mounted and fixed on the machine support, in place its movable lunette, and consists of a loading part 1 of part 5, represented by its body, mounted and fixed in the tool holder 3 of the machine.

 In the opening of the housing 5 of the loaded part of the device, it is located perpendicular to the surface of part 1 spring-loaded and pressed towards the workpiece, wire coil spring (s) 9 and disk springs 10, and if necessary with compressed air, a plunger 8 containing in its closest to the part 1 part of the groove in which the finger 11 is mounted with the possibility of swinging in a plane perpendicular to the surface of the part 1, a two-arm lever 12, on the permutable cams 13 of which are mounted and secured with self-adjusting screws 14 ayuschiesya pivotally relative to the surface of the part 1 7 hard wear-resistant inserts forming a parts of 1-slot wedge prism.

 The wire coil spring (s) 9 is adjusted for preliminary force by the screw 15 through the washer 16.

 On the opposite side of the plunger 8 with respect to the workpiece, there is a cavity 17, the pressure of the compressed air in which is regulated and supported by the pressure reducing valve 18 at the end of the plunger 8.

 The intermediate supporting part 4 of the device contains a plunger 19, located mainly perpendicular to the axis of the workpiece 1. On the adjacent to the part 1 end of the plunger 19 there are inserts 6, which are able to move together with the plunger 19 onto and from the plunger 19 by means of screw 20.

 Screws 15 and 20 are locked with nuts 21.

 According to the method, the load P from the pressure (load) part of the device is assigned depending on the diameter of the workpiece and the distance between the intermediate support part of the device and the pressure (load) part of it, while the load force applied by the pressure (load) part is less than the force that causes the part (processed) stresses that exceed the true ultimate stresses of the elastic limit, and the sum of the stresses in the workpiece from the load of the loading part of the device and internal stresses are processed of the workpiece, taken in the same direction, the sign exceeds the true ultimate stress of the elastic limit, reaching the true yield stress of the material of the workpiece.

 For operation of the device, the supporting part 4 thereof is installed and fixed on the support of the machine, in place of it under a movable rest.

 By screw 20, the plunger 19 together with the inserts 6 is fed until the inserts 6 are in contact with the surface of the workpiece 1.

 The pressure (load) part 5 of the device is installed and mounted in the tool holder 3 of the machine. By moving the tool holder 3 by moving the upper slide of the caliper, depending on the diameter of the workpiece, set the distance along the axis of the workpiece, between the liners 6 of the supporting part and the liners 7 of the loading part of the device.

 The smaller the diameter of the workpiece, the smaller the required distance between the inserts 6 and 7, and vice versa.

 Next, the support and loading parts are shifted to the right by the longitudinal stroke of the caliper so that the inserts 7 of the loading part are at the edge of the workpiece 1, after which the transverse stroke of the caliper in the direction of the part 1 makes force contact between the liners 6 of the supporting part and the inserts 7 of the loading part with the force to be processed , which in itself does not cause stresses in the part exceeding the true elastic limit of the material of the part. In this case, the springs 9 and 10 are compressed. Part 1 is informed of rotation, and the machine support, together with the intermediate support 4 of the device fixed to it and the part 5 loading it, moves in the direction of the machine chuck 2, while the workpiece 1 is bent, twisted by friction, and its layers are compressed and stretched.

 When the supporting part reaches the cartridge, they change the direction of rotation to the opposite and move the parts of the device with the support towards the free end of the workpiece. In this case, the unstable residual stresses of the workpiece are destroyed or become sufficiently stable. Subsequent finishing machining by cutting or heat treatment leads of the parts will be minimal and in many cases acceptable.

 The part processed before finishing by the proposed method, at operational loads is less prone to leashes.

 If it is necessary to load the workpiece with a sufficient load, compressed air is supplied to the cavity 17 under the plunger 8, the pressure of which is regulated and maintained by a pressure reducing valve 18.

 The adjustment of the loading device to the diameter size of the workpiece is achieved by moving the cams 13 on the shoulders of the two-arm lever 12 and then fastening them to each other by means of reciprocal gear elements and screws 14.

 According to the proposed method, residual stresses in machine parts are destroyed or become stable, which improves their quality and service life.

Claims (3)

 1. A method of reducing internal stresses in shaft-type parts, which consists in applying force actions to the workpiece during its rotation by means of the tool’s working surface, characterized in that the part is cantilevered in the rotation means and introduced into the cantilever part surface in contact with the sliding support, and to the opposite sliding support lying on the other side relative to the longitudinal axis of the part and shifted to the side of the free end of the part on top of it awns of force applied causing bending stresses in the part, stretching, compression and torsion in synchronous moving the sliding support and the working surface of the tool and the periodic change in the direction of rotation of the items.  2. The method according to claim 1, characterized in that, as an embodiment, the working surface of the tool is made in the form of covering the surface of the part with mutual force friction of the wedge-shaped slit of the prism.  3. The method according to claims 1 and 2, characterized in that the sum of the stresses in the workpiece from the load and internal stresses of the same direction of the sign exceeds the true ultimate stresses of the elastic limit.

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