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How to improve the passing rate of cylindrical roller bearings 2012-01-03
Cylindrical roller bearing is a rotating high precision, with precision, the main radial load bearings, mainly for large precision machine tool spindle and finishing equipment, roller bearing on. In recent years, this type of bearing has become a large bearing Luoyang Bearing Group, the leading business unit product production and processing, output value accounting for about one-third of the division. However, due to the division in the past followed the old production process and processing methods, resulting in a package bearing a lower pass rate (only 60%), resulting in an enormous waste of material and working hours, thus affecting the division to further improve economic efficiency.
First, select the object
Cylindrical roller bearings are divided into single row, double row, four other categories, but careful study of their structural features have much in common: straight roller, welding protection, etc.. Thus in the production process problems are very similar, so the optimization process of the content will be very similar, so choose the largest annual short cylindrical Ball Bearing, "32672", represented by models to optimize the test process structure, and experience to promote Bearing in other models to processing in order to obtain more substantial economic benefits.
Second, the status and problems of production and processing
1, "32672" bearings, coat system with Gcr15simn steel processing, the size of the larger series, heat treatment and quenching process is difficult to control the shrinkage and deformation, often resulting in large and oval after quenching without grinding allowance, resulting in , the jacket size is too mill raceway.
2, "32672" bearing, oval coat roller quenching due reason, resulting in uniform allowance, so that processing of residual stress is uneven, resulting in ring raceway after the final grinding dimensions unstable, difficult to control the process within the provisions of .
3, "32672" bearing, roller coat the beginning of grinding, due to aging and other causes of machine tool grinding spindle rotation accuracy is low, after the formation of coarse surface raceway edge degree, resulting in the final super-size roller mill after difference.
4, the technical coordination of work to keep up. For these causes, "32672" roller mill had affected the entire bearing assembly clearance, resulting in clearance failure, resulting in the rotation center of the bearing of uncertainty, resulting in cage center diameter is too large or too small (retainer diameter hole centers are regulated processing of uniform size), often have less flexibility and rotating bearing clearance of the phenomenon of uneven, this has led to "32672" bearing a complementary pass rate was 60%, also resulted in assembly work, processing (drilling, welding) cage materials, working hours and unnecessary waste.
Third, programs and measures to improve
To solve the above problem, "32672" bearing the original processing technology has been optimized to improve, the technical measures taken include:
1, in order to prevent heat treatment and quenching, and deformation-free allowance, positive contact with the heat treatment plant, with the control of deformation and heat treatment provided under the contract the amount of plant data, appropriate adjustments raceway allowance. This ensures that the heat treatment after quenching, grinding allowance in line with technical requirements.
2, the end mill dimensions in order to prevent instability in the original processing technology adds additional tempering process, in order to eliminate the stress process, to ensure the stability of raceway size.
3, through the transformation, repair machine tools, to improve accuracy of spindle rotation, and control the amount of feed and other appropriate measures to improve the early mill raceway surface finish to prevent excessive wear raceway.
4, through coordination with the production scheduling department, under the premise of ensuring the production schedule, the process structure to be processed by the shrinkage of high-impact set within a raceway to raceway excessive wear, including sets of circumstances, through technical analysis and calculation , to develop appropriate measures (coat may be appropriate to change due to wear and maintain the device center hole diameter) to ensure complete pass rate.
5, the final compression roller mill tolerance to size (number of) uniform in a small range, a small difference each other. This ensures complete a pass rate further increased, saving a lot of time with the clearance.
The use of optimized grinding process to guide the production, the "32672" short Cylindrical Roller Thrust Bearings supporting a 60% pass rate increased to 96%, significantly reducing the failure rates, saving hours of work and materials, reducing production costs.
