With the continuous development of the market economy, maintaining and improving product quality has become one of the most critical factors in determining success or failure in market competition. This holds true for the bearing industry as well. The entry into the WTO and the expansion of international trade have brought more challenges and pressures to the sector. The production of bearing rollers is a highly complex process that involves multiple stages and requires precision at every step. During the forming process, various factors can impact the final quality of the roller. For instance, when using a cold heading machine to punch out roller blanks, some products may be defective or even scrapped due to issues like under-pressurization, stacking damage, pitting, or deformation.
In one case, we produced bearing rollers on a Z31-25 cold heading machine. Although the rollers were initially qualified after stamping, some of them developed a curvature and experienced elastic recovery over time. Upon investigation, we found that the raw materials might not have met ideal standards during processing. To address this, we needed a more rigorous alignment system to ensure the straightness of the raw material, which would ultimately improve the quality of the finished roller.
**1. Process Analysis**
During the production of bearing rollers, several quality issues often arise. One common problem is the squeezing and deformation that occurs during the stamping process. These issues can significantly affect the performance and durability of the final product.
(1) **Under-Pressurization**: As shown in Figure 1, the thickness and length of the roller vary significantly. These shape differences can affect the overall quality after forming. Additionally, the bending of the raw material hinders the feeding process, leading to uneven pressure distribution and further quality problems.
(2) **Deformation After Compression**: Even if the roller appears to be properly formed after stamping, it may later develop a curve due to elastic recovery, as seen in Figure 2. Initially, we used a one-way straightening device to solve this issue, but after some time, the problem persisted. Further analysis revealed that unidirectionally curved materials could be corrected, but bi-directionally curved blanks were much harder to fix. This led us to develop a bidirectional straightening device, which proved more effective in handling multi-directional bending.
**2. Principle of One-Way Straightening Device**
The one-way straightening device is positioned before the cold heading machine to align and stabilize the raw material. It helps correct unidirectional bending, which is common in many production scenarios. By adjusting the handwheel, the moving plate drives the D4 and D5 wheels to move back and forth, effectively pre-straightening the material. This device works best on smaller machines like the Z31-13, where the smaller diameter of the roller allows better control over material bending.
**3. Bidirectional Straightening Device and Its Principle**
For larger machines like the Z31-25, where the roller is thicker and more prone to multi-directional bending, a one-way straightening device proves insufficient. To address this, we designed a bidirectional straightening device. This device adds two sets of one-way straighteners arranged at a 90-degree angle, allowing for more comprehensive correction. However, early versions faced challenges with feeding and pressure issues. To resolve this, we added 204 bearings to each straightening wheel to improve rotation and reduce resistance. We also reinforced the structure with ribs to enhance strength while reducing weight. After re-testing, the results were very promising.
**4. Effectiveness of the Two-Way Straightening Device**
We tested the two-way straightening device on the Z31-25 cold heading machine. The table below shows the improvement in compression conditions before and after its use.
[Image: A table showing the improvement in compression conditions]
As shown, the two-way straightening device made a significant difference in the quality of the raw material, reducing bending and improving overall performance. This device is recommended for widespread use, as it offers excellent economic benefits and improves production efficiency.
**5. Conclusion**
The original one-way straightening device was unable to handle multi-directional bending effectively. To overcome this, we developed and implemented a two-way straightening device, which has proven to be highly beneficial. It reduces waste, minimizes material bending, and enhances the overall quality of the roller. This innovation plays a vital role in the cold forming process and contributes significantly to production efficiency and cost savings.
Aluminum Tube,Aluminum Making Production Line,Steel Tube Production Line,Welding Production Line
Yangzhou Donglun Industrial Equipment Co., Ltd , https://www.dltubemill.com