Method of making helical springs

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used for making high-loaded helical springs subjected to both axial and radial forces. Proposed method comprises spring coiling, thermal treatment, preparing thrust coils, cold upsetting, and shot-blast cold-hardening of spring outer surface section. Length of said section makes one fourth of spring turn circumference to half the circumference. Preset spring outer surface section is subjected to ordered shot-blast cold-hardening.

EFFECT: higher fatigue resistance, quality and strength.

4 dwg

 

The invention relates to mechanical engineering and can be used in the manufacture of springs of steel.

The known method of increasing the fatigue strength of the elastic elements are coil springs, torsion, leaf springs used in the manufacture of these items, the processing of the surface flow fraction, called by shot peening.

The application of this method for the coil springs of steel provided by the state Standards (GOST 1376486. Springs cylindrical helical compression and tension steel of circular cross section. The classification. GOST 1452-2003. Cylindrical helical springs trucks and shock traction devices rolling stock). In this way the spring is fed into the chamber for guiding the rotating shaft, where it is within a few minutes exposed to the flow of the fraction (the flying speed of the pellets 70-120 m/s, the diameter of the pellets 0,8-1,2 mm). The flow fraction is formed in the shot blasting machine shot blasting installation (Odintsov L.G. Hardening and finishing details by surface plastic deformation, Moscow, Mashinostroenie, 1987).

When the flapper fraction under blows of pellets plastic deformation occurs in the surface layers of the metal coils of the spring - hardening to a depth of 0.1-0.4 mm

The disadvantage of this method is to process the entire surface of the springs, while the e is able to provide optimum fatigue resistance, in cases impact on spring simultaneously with the axial load and lateral force causes the redistribution of stresses in the coil spring with the emergence of stretching of the outer fibers by the action of shear forces, where the emergence of cracks and failure of the spring.

The objective of the invention is to increase the fatigue strength and durability of heavy-loaded springs, which are combined, including axial and lateral force load.

The technical result consists in the neutralization of the tensile stresses of the outer coils of the spring from the action of shear forces through the implementation of purposeful influence on the outer surface of a given section of the spring blast-hardening.

This object is achieved in that a method of manufacturing a cylindrical coil springs includes winding the spring, the heat treatment, the preparation of the reference coils, cold draught, the operation blast of cold working. Blast hardening of the exposed predetermined area of the outer surface of the spring. The specified area of the outer surface is formed by a half of the circumference of a coil spring. The specified area of the outer surface is equal to one quarter of the circumference of a coil spring. The specified area of the outer surface is equal to one the third of the length of the spring from each of the reference coil spring. Preparation of the reference coils includes the steps of cutting and polishing the ends of the reference coils.

Examples of the proposed method are presented in figures 1-4, which reflects the treated areas of the outer surface of the spring.

The method is as follows.

Machined spring is placed in the opening fixture, fix, placing inside of a spring element that protects the lower part of the inner surface of the coils of the spring from the influence of flow fraction.

Open, accessible to the impact of the fraction remains only the upper part of the surface of the spring. Figure 1 shows the surface E, which represents the upper half of the circumference and a coil spring along its entire length. Figure 2 - this surface E - the upper sector of the circumference of a coil spring constituting the fourth part of the circumference of a coil spring, also throughout its length. Figure 3 and 4, the surface F is formed in the same parts of the circumference of a coil spring, and the treatment machine parts up to 1/3 of the total length of the spring from each of the reference coil, the middle section is covered by a protective element of the device.

The device, together with the spring moves the camera shot blast machine without rotation only in the direction along the axis of the spring. The device is set so that the s upper open part of the coils of the spring was directed towards the flow of the fraction.

In the hardened layer increases the hardness, yield strength increases by increasing the number of dislocations specific volume of the metal, resulting in a plastically deformed layer internal compressive stresses.

The increase in yield stress leads to increased levels of stress, causing the nucleation of fatigue cracks by the action of shear forces and compressive residual stresses are formed with tensile stresses that occur during operation nagruzhennosti, reducing the latter, cause the hardened surface coils operate at lower voltages, which increases the life of the spring. In addition, the compressive residual stress, counteracts the stress concentrators, which have a depth commensurate with the depth distribution of residual compressive stresses. All this together has a hardening effect increases the level of the allowable working stress and the service life of the springs.

The inventive method of manufacturing helical springs was tested in the manufacture of cylindrical helical compression spring with an outer diameter of 100 mm, internal 76 mm, made of steel grades SA and FA.

Studies of the quality and strength characteristics of the springs showed that when tested by the research Institute on fatigue durability reinforced by the present method springs up to 10 times the durability of conventional springs.

Thus, the inventive method of manufacturing a cylindrical coil springs allows you to receive a higher level of fatigue strength of cylindrical helical springs and durability, working under complex loading.

1. A method of manufacturing a high-loaded helical springs exposed simultaneously axial and shear forces, which includes the winding of the spring, the heat treatment, the preparation of the reference coils, cold draught and the blast gets smaller the area of the outer surface of the spring, the value of which is one quarter of the circumference of a coil spring to one-half the circumference of a coil spring.

2. The method according to claim 1, characterized in that the area of the outer surface of the spring subjected to blast the cold working, up to one third of the length of the spring from each of the reference coil spring.

3. The method according to claim 1, characterized in that in the preparation of the reference coils springs are trimming and polishing their ends.



 

Same patents:

FIELD: process engineering.

SUBSTANCE: invention relates to machine building and may be used in devices intended for increasing spring capacity and working performances. Proposed device comprises barrel to receive inserts and spring to be tested arranged there between. Barrel ID varies from compressed spring diameter to that of coiled spring. Punch with ball surface stays in contact with ball surface of top insert attached to said punch by screw with washer to rotate and displace relative to barrel axis and allow its axis to deflect from punch axis. Spline grooves are made on punch screw and top insert central bore to arrange spring-loaded alternating friction discs jointed by splines with punch screw spline grooves and top insert spline grooves. Insert end faces are provided with surfaces with thrust that features depth making, at least spring coil height to follow profile of the spring extreme coil end faces. Overrunning coupling with screw surface is fitted inside bottom insert to interact with screw surface of the rod coupled with press bottom cylinder ejector. Rod cylindrical section has alpines or spline groove to interact with mate splines or keys of the device bottom plate.

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FIELD: machine building.

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FIELD: process engineering.

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FIELD: process engineering.

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