1 Change of steel ball for acid-wash test in processing

In the process of hot pickling the large-size steel ball. It not only consumes the overall size of the steel ball. But also it because too large stress of both the poles and the girdle. Directly causes the steel ball to corrode too quickly. Moreover, the depth of the steel ball corrosion layer can reach 0.18 mm. It eventually leads to the occurrence of intergranular corrosion. On the one hand, need increase total flow rate of large steel ball processing. On the other hand, there is also in the process of processing large steel balls, reduce fatigue generate. So, use deep pickling instead of hot pickling. Also use the proper ratio of acids. The consume of the deep pickling is controlled at 0.03 ~ 0.04 mm for large steel ball. To verify the reliability of this method. A large ball of steel with a eddy current inspection and deep pickling of 400 particles, through related hot pickling test. No problems were found. It is feasible to replace the heat calculation-wash with eddy current testing and deep pickling.

2 Other improvements

2.1 Fine grinding of large steel balls. The working condition of the soft grinding is improved. Improve the quality of steel ball.

The processing equipment of fine grinding and soft grinding for large size steel ball is updated. The grinding wheel of the new steel ball machine can be automatically reshaped. Ensure that the large steel ball is in the best condition in the process of processing. And the actual verification results show that. The new equipment can improve the efficiency of grinding of large steel balls by 11 to 16 percent. In addition, in the process of fine grinding of large steel balls. Can effectively control the burn condition

2.2 Increase the hardness uniformity of large size steel ball

Change the air furnace heat quench to air protection quench. At the same time, it can effectively improve the hardness uniformity of steel ball surface, and the precision of the device for temperature control. The single hardness difference of large steel ball finished product is lower than 0.5 HRC. In large batches, the difference in hardness of steel ball is lower than that of 1 HRC(Human Resources Center)

2.3 The fatigue phenomenon that occurs when machining large steel balls is reduced

According to the characteristic of steel ball process in large size. Through the method of grinding for light. The steel ball soft grinding process is in the update and modification of the steel ball machine. Replace the ball mill process with the grinding wheel of 80 # ~ 120 # and automatic grinding wheel dressing system. This can eliminate the concentration of high stress that occurs during the processing ball. In the lapping process of large steel ball. The condition of steel ball processing is controlled effectively. Replace the oil grinding with water grinding. It can reduced the process effectively in steel ball grinding. It greatly reduces the fatigue phenomenon in the process of grinding steel balls. In the process of machine tool for grinding and processing steel balls. The surfactant semen was used in the form of an experiment. Test it in the form of an experiment(Surfactant semen, Emulsion intensive liquid as well as auxiliary equipment). Finally, the operation procedures and the ratio of grinding materials are determined. To ensure that the time of large steel ball grinding is reduced from 48 hours to 36 hours.

2.4 Improved steel ball preliminary working, Reduce steel ball working allowance

In the process of processing large steel balls. On the basis of its processing accuracy guarantee. Reduce steel ball working allowance. It can shorten the time of the steel ball grinding. It also reduces the metamorphic layer that occurs because of excessive grinding. Reduces the chance of the large steel ball grinding mass. According to the original bearing material performance. For hard alloy steel ball stamping tool, And the ancillary tools that are self-development. At the same time, the stress ball verification is repeated during production. These studies show that, The adoption of hard cutting fetus and alloy cutting board. Can improve the quality of steel ball cutting. And it also reduces the pressure folding.

In addition, the use of alloy pressure ball fetus. It can ensure that the ball fetus is not deformed at the time of stamping. The precision of the ball embryo is improved. In addition, the selection of steel ball cutting length and material diameter. Ensure that the compression ratio is within 2.0 to 2.2. There is also a guarantee of the pressure material segment. The optimum deformation condition of the material segment. Therefore, the size of the ball embryos finishing process is basically the same. And the band of ball is very thin and small too. This allows the processing allowance of large size steel balls to be reduced from 1.2mm to 0.8mm

（作者：张明松，朱亿宽，柯建军，朱普先    三峡大学机械与材料学院，宜昌    日期：2013年5月13日）

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