The production characteristics of traditional self-aligning roller bearing cage are as follows: long processing cycle, high manufacturing cost, complex technology, low production efficiency and unstable product quality. Therefore, it is urgent to rely on technological innovation to improve the manufacturing level of cage to meet the market demand.
Analysis of the original cage processing technology and tooling
- The cage structure of aligning roller bearing is shown in Figure 1. The main parameters affecting bearing rotation of cage are: inner diameter dc1, bottom diameter dc3, window size Lc and related shape and position tolerances, such as the position variation of bottom diameter center to outer diameter center VHc1, beam width variation VBc, window bottom high momentum Vhc, large end face flatness VF, etc. The main parameters affecting bearing assembly of cage are: outer diameter DC, width BC, window hole bottom hC and related shape and position tolerance, such as outer diameter variation VDc, bottom warping degree VB, etc.
1. Processing process flow
The processing process of self-aligning roller bearing cage is as follows: cutting material → cutting material → forming → punching device hole → punching window hole → shaping → pressing slope → cutting bottom → car bottom, bottom diameter → car face, chamfering → surface treatment.
2. Structural characteristics of the main die
According to the characteristics of the self-aligning roller bearing cage, it mainly designs and processes related tooling and fixtures for forming, punching device hole, punching window hole, pressing slope, car bottom surface and bottom diameter. The forming mold structure is shown in Figure 2. The cake cut in the process before positioning by the unloading ring is processed by the forming die and the forming punch to ensure that the semi-finished products meet the specified shape and size requirements.
The hole die of punching device is shown in FIG. 3. After the positioning ring is formed in the previous process, the inner diameter of the cage is positioned, and a flat round hole is processed by punching die and concave die. The hole is also the positioning hole processed in the next process.
The window punching die is shown in Figure 4. The semi-finished cage is fixed through the supporting plate, the positioning column and the nose pressure plate by the device hole; The punch of the punch hole is fixed on the punch joint, which is realized by the up and down movement of the slider of the machine tool; The die is fixed to the die joint according to the cage
Size adjustment nut to adjust its height on the punching machine. The action to complete the window punching process is as follows: (1) fix the cage on the supporting plate; (2) Move the cage to a suitable position and punch holes; (3) Return the workpiece and related mold to the original position after the completion of punching; (4) Loosen the nose press plate and take out the finished punching workpiece.
The slope pressing mold is shown in Figure 5. Put the cage hole beam into the slope pressing die, and the slope pressing punch moves down with the sliding block of the machine tool to press the hole beam into the concave die to complete the slope pressing process.
The bottom cutting mold is shown in Figure 6. The outer diameter of the bottom cutting die is basically the same as the inner diameter of the cage. The cage is positioned by the concave die, and the bottom cutting punch moves downward with the slider of the machine tool to complete the bottom cutting process.
Bottom surface, bottom diameter, end face and chamfering clamp  are shown in FIG. 7. The positioning body is designed according to the outside diameter or inside diameter of the cage, and the specific hc design card of the cage’s window hole size and bottom height. The cage is tightened by the cone shaft connected to the machine tool, and all the turning procedures are completed by the clamping tool.
3. Existing problems
The original cage processing technology is tedious, the cycle is long, in a short time to complete the processing of a product needs to invest more personnel and equipment, occupy more resources, high cost; Due to the different positioning datum of the mold used in each process, the size error caused by the processing cannot be excluded, so the cumulative size error is large; In addition, the mold structure is complex (especially the window die), the adjustment is difficult, the inventory management is complex.
Improvement of process and tooling
- 1 Improved process flow after the improvement of the process flow is: cutting → cutting, forming, cutting bottom → punching window hole → shaping → slope → car bottom, bottom diameter → car face, chamfering → surface treatment.
1. Improved mold structure characteristics
The cutting, forming and bottom cutting processes combine the original cutting, forming, punching device hole and bottom cutting into one process, eliminating the problem of cumulative error caused by different reference positioning surfaces. One processing can meet the coaxiality requirements of cage outer diameter, inner diameter and bottom diameter in bearing assembly. The improved composite die is shown in FIG. 8. When designing the die, the cutting and forming convex and concave die and the cutting bottom die are gap fit, and the matching surface should be properly raised. The gap should be strictly controlled. Cutting punch and forming punch adopt transition fit to control the coaxality of bottom diameter and outer diameter, and pay attention to the height difference between cutting punch and forming punch should not be too large, otherwise it is easy to cause the bottom diameter deformation. The cutting die is used to control the pie size of the cutting material.
The window punching hole mold is shown in Figure 9. It has good adjustability. The horizontal bar part, the support part, the concave die base and the concave die can all be adjusted from the lower die base to the left and right. For different types of workpiece design mold replacement parts only 3 pieces (punch, concave die and spring clip), improve the design and processing cycle of the mold. The action to complete the punching process is as follows :(1) fix the bottom diameter processed by the previous process on the spring clip head by pulling the cone; (2) punching; (3) After punching, return to tighten the cone, loosen the spring clip, and remove the workpiece.
The end face, bottom face and chamfering clamp are shown in Figure 10. The clamping tool takes the bottom diameter of the cage as the positioning size to design the specific card, through the left and right movement of the cone shaft connected to the machine tool to tighten or loosen the cage, to complete all the required turning process.
Comparison of data before and after improvement
Taking 22212CC and 22220CC bearings as examples, the data of the actual production of 10 000 pieces of 22212CC cages and 3 000 pieces of 22220CC cages were collected. After the improvement, the technical parameters of the cages all met the standard requirements, which was greatly improved compared with that before the improvement. Ensure the product quality level; The improved mold cost is greatly reduced, and the processing efficiency is increased by 20% ~ 30%.
The improved process method uses a datum (bottom diameter) positioning to avoid the cumulative error in the process and ensure the quality of the product; The process flow is simplified, the product processing cycle is shortened; The cost is reduced, the processing efficiency is improved, and it has good application value.