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The residual stress rubs and pares the influence out of shape on one set of circles of bearing


30th September 2010 Bearing Technology 0 Comments

Summary: To wasting paring the problem out of shape of one set of circles of thin wall bearing, analyze and discuss in terms of internal stress, propose relying mainly on adjusting the heat treatment craft, adjust and rub and pare the craft it for the method to complement, solve the rubing and paring the problem out of shape of one set of circles of thin wall bearing.

Keyword: One set of circles of bearing, rubing and paring the residual stress out of shape, quenching the flash back craft

Abstract: With regard to the issue of distortion from grinding of the thin wall-thickness bearing rings, it is mentioned to go through analysis or discussion from the riew-point of internal stress. Conclusion is to take adjusting the heat-treat process as the main while taking adjusting the grindin g process as the subsidiary. By this method we seek a final solution of the issue of distortion from grinding of the thin wall-thi ckness bearing rings.

Key words: bearing rings, distortion of grinding, residual stress, process of quenching and tempering.

A foreword

Our company one special producing bearing overseas-funded enterprise, produce to transfer heart, get away sub bearing international brand. In process of production, often the diameter change amount VDP after the rough grinding of one set of circles appears Exceed difference, the question that the back way process can’t be dispelled and scrapped. The inspection result is: Raw materials quality accord with U.S.A. ASTM A29 standard; The intersection of horse and body and remain body organize rank 1-2 respectively, crook the intersection of body and rank <1, the flash back hardness HRC60-62, the deformation of heat treatment meets JB/T 1255 standard; Through testing repeatedly, get rid of the possibility to rub unreasonable and apparatus question of paring the technological parameter; Wasting paring statistics out of shape and is shown in Table 1 of one set of circles.

This text will organize discussion on forming reason and solution of the above problem.

2.Analyze

Show from observed above phenomenon, produce, rub, it pares out of shape to be material and heat treatment quality index not up to standard, also rub and pare the apparatus and craft respecting caused, we are thought through careful analysis, internal stress is to cause one set of circles to rub and pare the basic reason out of shape.

As everyone knows, the part with internal stress, its internal organization is in a kind of unstable state, it tends to be strong and wants to return to a steady one state of the stress does not, even part at room temperature will be slow and carrying on this kind of change constantly, until disappear in internal stress. In this transformation, shape and original precision of the part will be influenced.

Rub and pare the stress source out of shape and come from two respects this time:

Residual stress of the heat treatment

One set of circles causes the nonconformity of cooling speed and shrink intensity by every part of thickness irregularity in quenching etc. the hot processing course, and the volume which the metallography organization changes is changed, all make the inside of one set of circles produce significant internal stress. Sets of circle to have internal stress find out what does it have out of shape, because internal stress it ins to be relatively balanced state still at this moment in a short time. But after rubing some surface layers, the equilibrium is destroyed, internal stress is distributed again, one set of circles presents deformation obviously, even cause the crackle.

Rub and pare the stress

First of all, in the course of rubing and paring, the superficial floor of a circle is under cutting strength, cutting hot function, also the volume that the change that will produce the plasticity metal out of shape at various degrees and organize causes changes, make the work piece surface layer produce internal stress. After processing again, internal stress is distributed again, make one set of circles deformed. Secondly, because the wall of one set of circles is thick and relatively small, as external diameter being the larger the worse the rigidity of the set of circles is, it resists out of shape ability to be bad, sets of the intersection of circle and the intersection of size and structure pay no attention to, cause, rub deformation increase while sharpening easily.

So, we have confirmed and solved and rubed the step which pare the problem out of shape:

*Find out about distribution and size of the heat treatment stress of one set of circles;

*Further reduce the internal stress of one set of circles;

*Solve and rub and pare deforming.

3. Test method and result

3.1 test methods and testing the condition

Test method:

Select each two pieces of heat treatment and one set of circles of external diameter 80,100,110 at first, choose one to examine some on every exterior round of one set of circles through 90o, examine some serial numbers A, B, C and D, the residual stress annularly of round surface outside of test.

Test the condition:

Adopt the Model X350A X ray stress appearance, measure the parameter: In charge of the voltage 25kV, electric current 5mA, Cr target K










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