RU2688028C1 - Method of manufacturing helical cylindrical springs - Google Patents

Abstract

FIELD: machine building.SUBSTANCE: invention relates to machine building and can be used in making helical compression cylindrical springs. Method includes winding of spring with pitch exceeding that of finished spring, heat treatment, lumocontrol, shot blasting and grinding of spring ends. At the final stage, the outer and inner surfaces of the spring are cold-formed, which is performed by expanding the spring turns to the surface of the matrix hole by the male die, and cold-hardening of spring surface along contact line of turns to each other by means of hardening device when spring is located in die hole, which is performed in process of plastic deformation of spring at expansion of turns by male die due to applied axial force, wherein said operation is performed with spring free ends that are not secured in tangential direction and have free rotation possibility.EFFECT: higher efficiency of spring manufacture and stability of elastic properties of reinforced spring.1 cl, 1 dwg

Description

The technical field to which the invention relates.

The invention relates to mechanical engineering, in particular to a method of hardening helical cylindrical compression springs.

The level of technology

There is a method of hardening the springs - shot-bending treatment, which is the most common in the production of springs. The essence of the shot-processing process is that the parts, after the final mechanical or heat treatment, are subjected to the impact of a stream of steel or cast-iron shot. Shot blasting springs produced on mechanical or pneumatic shot blasting machines with steel or cast iron shot with a diameter of 0.4 to 1.8 mm (Ostroumov VP Production of helical coil springs / VP Ostroumov. - M .: Mashinostroenie, 1970. - 135 pp., Pp. 74… 75).

During shot-blasting, bilateral residual compressive stresses are created on the surface of the coils, which prevent fatigue cracks from opening and increase the endurance limit by 40-80% (Lavrinenko, Yu.A. Spring Hardening / Yu.A. Lavrinenko, EG Belkov, V.V. Fadeev. - Ufa: Business Partner Publishing House, 2002. - 124 p.).

The disadvantage of this method is that shot blasting does not eliminate the uneven distribution of stresses over the cross section of the spring coil. The coils of the coil spring usually have significant curvature. This leads to a significant increase in stress, reaching 40% on the internal fiber of the turns, compared with the stresses that occur on the external fiber of the turns. (Ponomarev, SD. Calculation of the elastic elements of machines and instruments / SD Ponomarev, L.E. Andreeva. - M .; Mashinostroenie, 1980. - 326 p., P. 88). During the operation of the spring, fatigue cracks develop on the inner side of the coil section.

It is known that the greatest stability of elastic properties depending on the type of processing of the spring is shown after processing in a stressed state (Ostroumov, VP, Production of helical coil springs / VP Ostroumov. - M .: Mashinostroenie, 1970. - 135 p., S 93 ... 96). By analogy with this, the shot blasting of the springs should be carried out in a compressed state before the contact between the coils (the stressed state). When the shot-blasted processing of the compressed spring, the flow of the fraction reaches only the outer side of the coils, and the inner side of the coils will remain unstressed, which is a disadvantage.

There is a method of hardening cylindrical coil springs, including winding, quenching, tempering, shot blasting and zevolivanie, and at the final stage, the work hardening of the inner surface of the springs. Stiffening is carried out using pulling the mandrel or shock impact on the inner surface of the coil spring. The proposed devices for implementing the method — dorn or reinforcing head with rollers — are mounted on a lathe in which a spring is fixed in the fixture (Patent RU 2462519, IPC C21D 9/02, C21D 7/06, B21F 35/00. Method of hardening cylindrical helical springs / OI Shavrin, 2011115786/02; announced 04/20/2011; published September 27, 2012, Bull. No. 27).

The disadvantage of this method is the difficulty of fastening the spring in the fixture of the lathe and the possibility of damage to its turns when

uneven distribution of clamping forces and forces from pulling the mandrel or from the impact of the head rollers of an unnamed model (brand).

The disadvantages are also the duration of the processes: installation of the spring in the device and removal from it, bringing the spring and working tool into rotation (mandrel or roller head), supplying and discharging the working tool. The issue of removing the spring from the working tool is not resolved, which is also a disadvantage.

The disadvantage is that this method does not strengthen the coils of the coils operating with the contact, because when this method of hardening is hardened, no coils along the contact line between them occur.

A known method of hardening helical coil springs (Patent RU 2625196 C1, IPC B21F 35/00, C21D 9/02, F16F 1/06 The method of hardening helical coil springs / Tebenko Yu.M., 2016139728; announced 10.10.2016; published 12.07.2017 Bulletin No. 20. The method consists in winding the spring with a step exceeding the finished spring pitch, heat treatment, shot-blasting, lyumocontrol, grinding the ends of the heat-treated spring, compressing the spring until the turns come in. At the final stage, the external and internal surfaces are hardened. szh the spring and the work hardening of the surface of the compressed spring along the line of contact between the turns by means of a hardening device when the compression spring is in the die hole. The outer and inner surface of the spring is compressed by expanding the spring coils to the hole surface of the die with the die diameter of the compressed spring. The gap between the hole of the die and the surface of the punch is chosen less than the diameter of the coil spring by 0.2 ... 5 mm. An overlap of the surface of the compressed spring along the contact line of the turns between themselves is produced by compressing the spring with a force of 5 ... 300F3, where F3 is the spring force at maximum deformation.

The prior art also knows the specific features of the method described above, in which the gap between the die hole and the punch surface is chosen in the range of 0.2 ... 5 mm depending on the spring geometry (RU 2623847 C1, IPC B2F 35/00, C21D 9/02 , F16F 1/06, published on 06/29/2017), a wire or a rod is used as a blank, and the internal and external surfaces of the compressed spring are hardened and the surface of the compressed spring is hardened along the contact line between them in a single return operation atomic-translational movement of the punch through the entire spring (RU 2601015 C2, IPC B21F 35/00, C21D 9/02, F16F 1/06, publ. 10.27.2016).

The disadvantage adopted for the prototype of the method is quite complex technical implementation of technological equipment and tooling. The method involves a significant change in the shape of a circular profile of a wire or a rod of a wound spring, which in turn will lead to a decrease in the preliminary and working forces of the spring for given displacements and a significant change in the geometry of the spring.

DISCLOSURE OF INVENTION

The objective of the invention is to increase the stability of the elastic properties of the spring and reduce the time of installation and removal of the spring from the device and the time of hardening of the springs. The technical result, the achievement of which the invention is directed, is to create plastic deformations of the work hardening on the outer and on the inner surfaces of the coils of the spring and the surfaces in the line of contact between the coils.

The technical result is achieved by the fact that the method of manufacturing helical coil springs includes winding the spring from a pre-reinforced or hardened wire / rod with a step exceeding the pitch of the finished spring on

the amount of allowance for strengthening operation, heat treatment - tempering for springs from pre-hardened wire / rod or quenching and tempering for springs from hardened wire / rod, lyumocontrol, shot-blasting, face grinding. The overlap of the outer and inner surfaces of the spring and the cold-leafing of spring surfaces along the line of contact between the coils and the spring reinforcement device located in the matrix hole is produced by bursting its coils to the surface of the matrix hole with a punch entering the spring, and the diameter of the matrix hole is smaller than the diameter of the compressed spring, and the gap between the hole matrix and the surface of the punch choose less than the diameter of the wire / rod by 0.2 ... 5 mm, depending on the geometry of the spring. An overlap of the surfaces along the line of contact of the turns between themselves is carried out in the process of plastic deformation by widening the turns with a punch in the direction of the matrix wall. The work-hardening of the inner and outer surfaces of the spring and the work-hardening of the spring surfaces along the contact line between the coils are performed in one operation, and the plastic deformation operation is performed with the spring end surfaces loose in the tangential direction, having the possibility of free rotation.

Brief Description of the Drawings

The method is illustrated by drawings, where in FIG. 1 shows a possible design of a device for carrying out the method, in which the punch is in the upper position before performing the operation of strengthening the spring; in fig. 2 shows a possible design of a device for carrying out the method, in which the punch is in the lower position during the spring hardening operation.

The implementation of the invention

A method of manufacturing a helical coil springs as follows. The spring (5) is wound with a step exceeding the step of the finished spring by the amount of allowance for the hardening operation, heat treated, carry out lumocontrol, make shot-blasting processing, grind the ends. The external and internal surfaces of the compressed spring and the pressure surfaces of the compressed spring are applied to each other by means of a hardening device when the spring is in the die (3), and the external and internal surfaces of the spring are turned by bursting the spring coils to the surface of the matrix hole. it has a punch (2), and the diameter of the die hole is less than the diameter of the compressed spring, and the gap between the die hole and the surface of the punch is chosen smaller than the diameter of the wire Loka / bar 0.2 ... 5 mm, depending on the geometry of springs. An overlap of the spring surfaces along the line of contact of the turns between themselves is carried out in the process of plastic deformation by bulging the turns with a punch in the direction of the matrix wall.

In the case of using a punch consisting of sections: a guide part with a diameter smaller than the internal diameter of the spring, the lead-in cone, the calibrating part with a length not less than the height of the compressed spring, the shank for fastening in the elements of the process equipment is strengthened when moving “forward” —the movement of the calibrating part through the reinforced spring the direction of the support element (4) located at the base of the matrix, while moving “backward” - towards the removable device located at the top of the matrix GSI eat the hardened spring from the punch. The removable device can be implemented as a profile puller (6) with a hole for the first bolt (1) and figured cuts for the calibrating part of the punch (2) and the second support bolt.

In the case of using a profiled punch consisting of sections: a guide part with a diameter smaller than the internal diameter of the spring, a lead-in cone, a calibrating part of a length not less than 4 diameters of the wire / rod, a return threaded

cone, rear guide part, shank for fastening in elements of technological equipment, hardening is performed in two successive movements of the calibrating part through a reinforced spring: “forward” - in the direction of the base of the matrix, “back” - in the direction of the removable device located in the upper part of the matrix. When moving “backward”, the hardened spring is also removed from the punch.

To reduce the torque relative to the axis of the spring tested by the spring during compression in the process of hardening, the end surfaces of the spring may be able to rotate freely due to the free rotation of the support surfaces of the tooling. The possibility of free rotation about the axis of the reinforced spring can have a contact surface of the support element (4) and a support element of the removable device.

In this case, the work hardening of the inner and outer surfaces of the spring and the hardening of the surfaces along the line of contact of the coils between them is carried out in one operation.

Using this method, it is possible to create in one operation on the inner and outer surfaces of the spring and along the line of contact between the coils plastic deformations (hardening) that increase the life of the spring operating under conditions of prolonged cyclic loading, including force or impact contact of the coils.

The presented operation of the hardening of the springs allows creating on the inner and outer surfaces of the coils of the springs and on the surfaces along the line of contact of the coils between them compressive residual stresses, which add up to tensile stresses arising during the operation of the spring, and reduce them.

The presented operation of hardening the inner and outer surfaces of the spring and surfaces in the line of contact between the turns is more productive than the well-known operation of hardening the inner surface by turning, because it can be implemented on a high-speed press and can be mechanized using the devices used in punching remove parts from it. The installation time of the spring in the device for hardening and removing the spring does not exceed 1 ... 2 s, while the installation time of the spring in the lathe jig, the rotation and pushing time of the mandrel or rollers on the inner surface of the spring and the time for removing the spring from the lathe jig is significantly exceeds the time of the operation of hardening on the proposed method.

The presented method in relation to the prototype is simpler in technical implementation and does not lead to a significant change in the spring geometry.

It is assumed that the durability (resource) of the springs hardened in this way will increase by 1.4 ... 2 times relative to the durability of the springs without hardening, which is consistent with the literature data.

The proposed invention in comparison with the prototype and other known technical solutions has the following advantages:

- hardening of the inner and outer surfaces of the spring and the surfaces in the line of contact of the coils between them is performed in one operation;

- increase the stability of the elastic properties of the springs;

- high performance hardening springs.

Claims (1)

A method of manufacturing helical cylindrical springs, including winding springs with a step greater than the step of the finished spring, heat treatment, lyumocontrol, shot blasting, grinding the ends of the springs and the work hinge surface of the compressed spring, while the spring and the inside surfaces of the spring are hardened when the spring is in the die hole by bursting turns of the spring to the surface of the hole of the matrix by the punch entering into it, and the surface of the compressed spring is hardened along the contact line of the turns between them in the plastic process This means that a die with a hole diameter smaller than the diameter of the compressed spring is used, and the symmetrical gap between the die hole and the surface of the punch is chosen less than the workpiece diameter, while the internal and external surfaces of the compressed spring are hardened and the surface of the compressed spring is contact lines of coils between each other are performed in one plastic deformation operation with successive reciprocating movement of the punch h Res entire spring, characterized in that the plastic deformation is performed with unfixed in the tangential direction of the spring end faces, having the possibility of free rotation.

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