On December 14, the reporter learned from the Institute of Metals of the Chinese Academy of Sciences that the research team led by researcher Li Dianzhong and academician Li Yiyi of the Institute had recently successfully developed the main bearing with a diameter of 8 meters for the super large TBM, marking that China has mastered the independent design, material preparation, precision processing, installation, commissioning, testing and evaluation and other integrated technologies for the main bearing of theTBM.

Realize independent development and production of main bearings

In 2020, the Chinese Academy of Sciences launched the strategic leading science and technology project of "independent and controllable manufacturing of high-end bearings" (hereinafter referred to as the "leading project"), gathering national strategic scientific and technological strength, and opening up the "last mile" of independent and controllable manufacturing of high-end bearings.

Li Dianzhong, the leader of the leading project, introduced that the main bearing is the core key component of the cutter head drive system of the TBM. During shield tunneling, the main bearing "hand-held" cutter head rotates to cut the face of the tunnel and provides rotary support for the cutter head. The main bearing with a diameter of 8m, weighing 41 tons, is the first TBM main bearing with the largest diameter and single weight manufactured in China. The main bearing will be installed on a super large TBM with a diameter of 16m for tunneling.

The leading project brought together 7 scientific research institutions of Chinese Academy of Sciences, including the Institute of Metals of the Chinese Academy of Sciences, formed an organic team, and cooperated with universities, institutes and enterprises nationwide to tackle key problems. It successively tackled 12 core key technical problems in the preparation of main bearing materials, precision machining and complete design, and developed 10 sets of TBM main bearings with diameters ranging from 3m to 8m. "The successful development of the main bearing fully reflects the wisdom and responsibility of Shenyang, which has been strongly supported by Shenyang Municipal Party Committee, the municipal government, Shenyang University of Technology, Northern Heavy Industries Group Co., Ltd., and Shenyang Metro Group Co., Ltd." Zuo Liang, director of the Institute of Metals, CAS, said that with the strong support and promotion of Shenyang Municipal Party Committee and the municipal government, The main bearing with a diameter of 3m has successfully completed the construction of the demonstration section of the extension line of Shenyang Metro Line 1, and is in good condition. The domestic largest and fully autonomous main bearing with a diameter of 8m has also determined the intended bid section for demonstration application.

Solve key technical problems from the source of materials

Previously, the main reason why the manufacturing of main bearings for super large TBM in China stopped was that the materials used to manufacture bearings and the processing accuracy of large rollers were not up to standard, and the technical chain of the whole process was not connected. According to Li Dianzhong, because the TBM can only move forward and cannot move backward in its work, the performance of the main bearing is highly required, and the problem of material manufacturing must be solved from the source. "We have targeted the research of rare earth bearing steel again," Li Dianzhong said.

Finally, the tension and compression fatigue life of the rare earth bearing steel is increased by more than 40 times, and the rolling contact fatigue life is increased by 40%. In 2022, relevant basic research achievements will be published in the internationally famous journal Nature Materials.

"On the basis of accurate analysis of the pain points, difficulties and blockages of the whole industrial chain of high-end bearings, we focused on the front end of the innovation chain and the core key technology links, and cooperated with more than 40 scientific research institutes and competitive enterprises to carry out joint research. It took less than three years to solve the" choke "problem of three types of typical bearings relying on imports, and achieved many significant results. This is an efficient organizational model for tackling key scientific and technological problems under the new nationwide system The beneficial exploration of the formula also found out the research paradigm of key basic components represented by high-end bearings. " Zuo Liang said.