QIBR cylindrical rollers are used in the transmission system of EMU gearboxes

Improve the accuracy of cylindrical rollers to ensure the stability of EMU operation

a) Challenges (existing problems and why they have not been solved)

In the transmission system of the EMU gearbox, the bearings are required to work under high speed and high load conditions, which is a great challenge for current bearings. For cylindrical roller bearings, they have the inherent characteristics of strong load-bearing capacity, but affected by the manufacturing process, their rotation accuracy is low and the limit speed is low.

The maternal principle leads to precision degradation, and the batch diameter variation is in the micron level. The batch diameter variation is worse than the accuracy of the centerless grinder. The sub-micron (0.35-0.8μm) batch diameter variation requires the support of a deep sub-micron (0.1-0.25μm) precision centerless grinder, which cannot meet the requirements for cylindrical roller bearings in the transmission system of the EMU gearbox.

b) Solution (How does QIBR solve the problem)

After analyzing the customer's requirements for roller bearings in the transmission system of the EMU gearbox, QIBR techniciansconducted direct comparison of multiple samples, selective material removal, and continuous convergence of diameter consistency on cylindrical roller bearings.

Taking the measurement results of cylindrical roller grinding (size: φ22×30 mm, batch: 500 particles) as an example, the experimental data are as follows:

1. The roller roundness gradually decreases with the increase of grinding cycles, and stabilizes after about 45 cycles; at about 60 cycles, the roller roundness reaches the minimum value of 0.39 µm.
2. At about 40 cycles, the roller roundness reaches below 0.5 µm, meeting the national standard G1 level accuracy requirements.

• The roller diameter variation gradually decreases with the increase of grinding cycles, and becomes stable after about 70 cycles; at about 75 cycles, the roller diameter variation reaches the minimum value of 0.74 µm.
• At about 40 cycles, the roller diameter variation reaches less than 1.5 µm, meeting the national standard G1 level accuracy requirements.

• The surface roughness after grinding is Ra0.01µm, which meets the national standard G1 level accuracy (Ra0.1µm).

From the above experimental data, it can be seen that the current industry level is level III precision and cannot be mass-produced. After QIBR research and development and improvement, the test results can reach level I precision indicators.

At present, QIBR has developed its own special process equipment, the cost is independently controllable (3 million yuan), far lower than imported equipment, and each production line can continuously produce 2880-5760 cylindrical rollers in 8 hours (5-10 per second, 50 cycles). Precision evolution processing technology, at this stage, the roller batch diameter variation is less than 1 micron; in the later stage, as the process matures, the processing accuracy has room for further improvement.

c) Results

1. The manufacturing process and precision of cylindrical roller bearings were optimized.
2. The stability and reliability of the EMU gearbox transmission system were improved.
3. The downtime of equipment caused by bearing problems was reduced.
4. The performance indicators of cylindrical roller bearings were improved.
5. The application requirements under high speed and high load conditions were met. 

Customer Testimonials

QIBR's technical experts provided us with QIBR cylindrical roller bearing products. When looking for bearings suitable for installation in the transmission system of the EMU gearbox and requiring the bearings to work under high speed and high load conditions, our company's procurement department contacted multiple bearing companies, but none of them could meet our requirements. Finally, we contacted QIBR's company and put forward the bearing requirements for our equipment. After communicating with QIBR technicians, the technicians provided us with several solutions and finally selected the most suitable one.

After installing the bearings, our company's technical department tested the transmission system of the EMU gearbox and obtained considerable data. Compared with the bearings used before, QIBR cylindrical roller bearings are very stable and reliable under high-number and high-load working conditions. Through cooperation with QIBR, we have greatly reduced maintenance costs.

The CEO highly praised QIBR and we will continue to choose QIBR's professional products and services.