The short cylindrical roller bearing is a kind of bearing with high rotation precision, precise matching and mainly bearing radial load. It is mainly used for the roller support of the spindle of the large precision machine tool and the finishing equipment. In recent years, this type of bearing has become the leading product in the production and processing of the large-scale bearing division of Luozhou Group, and the output value of production accounts for about one-third of the division. However, due to the past production process and processing methods of the business unit, the bearing qualification rate of the bearing is low (only 60%), resulting in huge waste of materials and working hours, thus affecting the further improvement of the economic benefits of the business unit.

 First, the selection of objects

 Short cylindrical roller bearings are divided into single row, double row, four column and other major categories, but careful study of its structural characteristics have many things in common: straight races, welding protectors and so on. Therefore, the problems in the production process are also very similar, so the content of the optimization process will be very similar, so the model of the short cylindrical roller bearing "32672" with the largest annual output is selected to represent the optimized process structure test, and the experience is extended to Other types of bearing processing are gone in order to achieve more economic benefits.

Second, the status quo of production and processing and existing problems

1. The "32672" bearing inner and outer casings are made of Gcr15simn steel. The size series is large. It is difficult to control the shrinkage and deformation degree of the heat treatment quenching process, which often causes the elliptical large and non-abrasive processing after quenching, resulting in The inner and outer raceways are oversized.

2, "32672" bearing inner and outer casing raceway due to quenching ellipse, resulting in uneven retention, so that the processing residual stress is not uniform, resulting in unstable ring race after the final grinding of the ferrule, it is difficult to control within the scope of the process .

3. When the "32672" bearing inner and outer casing raceways are ground, due to the aging of the machine tool equipment and other reasons, the grinding head spindle has low rotation precision, and the rough grinding after the raceway has a large ridge surface, resulting in a super-running raceway size. difference.

4. Technical coordination can't keep up. Due to the above reasons, the "32672" raceway over-grinding affects the assembly clearance of the complete bearing, resulting in unsatisfactory clearance, resulting in uncertainty of the center of rotation of the bearing, resulting in the center diameter of the retainer being too large or too small (retainer The center diameter of the hole is processed according to the specified uniform size), which often results in a decrease in bearing rotation flexibility and uneven play. This results in a "60672" bearing primary qualification rate of only 60%, which also causes assembly man-hours, machining (drilling, Welding) Unnecessary waste of man-hours and materials.

Third, improvement programs and measures

In response to the above problems, the original processing technology of "32672" bearing has been optimized and improved, and the technical measures adopted include:

1. In order to prevent heat treatment and quenching without any residue and deformation, actively contact with the heat treatment plant, cooperate with the control of the deformation amount, and adjust the raceway retention according to the heat treatment shrinkage data provided by the plant. This ensures that the heat treatment after quenching and grinding processing meets the process requirements.

2. In order to prevent the dimensional instability after final grinding, an additional tempering process is added on the basis of the original processing technology in order to eliminate the processing stress and ensure the stability of the raceway size.

3. Improve the surface finish of the raceway by modifying and overhauling the machine tool equipment, improving the spindle rotation accuracy, and controlling the feed amount to prevent the raceway from over-grinding.

 4. By coordinating with the production scheduling department, under the premise of ensuring the production progress, the process structure is changed to the first processing of the inner raceway which is greatly affected by the shrinkage amount, so that the technician can analyze and calculate under the condition of over-running of the inner raceway. , to develop corresponding measures (the outer casing can be under-grinded and change the center diameter of the retainer hole) to ensure the matching rate.

 5, the compression raceway final wear tolerance zone, so that its size (a batch) is unified in a small range, the difference between each other is small. In this way, the qualification rate of the matching one is further improved, and a large amount of matching time is saved.

Since the optimized grinding process has been used to guide the production, the qualification rate of the “32672” short cylindrical roller bearing has been increased from 60% to over 96%, which greatly reduces the repair rate, saves man-hours and materials, and reduces production costs.