The first super diameter spindle bearing for shield machine in China has been successfully developed. The spindle bearing has a diameter of 8 meters and a weight of 41 tons. It is the spindle bearing for shield machine with the largest diameter and the largest single weight manufactured in China. It will be installed on the super large shield machine with a diameter of 16 meters for tunneling.
The spindle bearing was developed by Li Dianzhong, a researcher from the Institute of Metal Research of the Chinese Academy of Sciences, and Li Yiyi, an academician team, marking that China has mastered the integrated technology of independent design, material preparation, precision machining, installation, debugging, testing and evaluation of shield machine spindle bearings.
Shield machine is a major equipment for infrastructure construction, carrying the heavy task of crossing mountains, rivers and seas. Previously, China had realized the localization of shield machines, but the spindle bearings were imported. “The main bearing is the core and key component of the cutter head drive system of the shield machine. During the tunneling process of the shield machine, the spindle bearing 'hand-held' cutter head rotates to cut the face of the tunnel and provides rotary support for the cutter head.” Li Dianzhong said.
Li Dianzhong introduced that the maximum axial force carried by the spindle bearing with a diameter of 8 meters during its operation reached 100000 kN (equivalent to the gravity of 2500 Asian elephants), the radial force reached 10000 kN, and the overturning torque reached 100000 kN ยท m. In addition, the large shield machine can only move forward and cannot reverse during the tunneling process, which puts forward high requirements for the bearing capacity and reliability of the main bearing.
In 2020, the Chinese Academy of Sciences launched the strategic pilot science and technology project of “independent and controllable manufacturing of high-end bearings”. The metal research institute, Lanzhou Institute of Chemical Physics and other seven internal units formed a institutionalized team, and cooperated with more than 20 units, including CCCC Tianhe Mechanical Equipment Manufacturing Co., Ltd. and Luoyang Xinqianlian Slewing Ring Co., Ltd., to tackle key problems, and solved 12 core key technical problems successively, A total of 10 sets of shield machine spindle bearings with diameters ranging from 3m to 8m have been developed.
In order to prepare bearing steel materials with high purity, high homogeneity, high strength and toughness, and high wear resistance, the research team has developed the key technology of “low oxygen rare earth steel” after more than 10 years of continuous research. The tension and compression fatigue life of the developed rare earth bearing steel has been increased by more than 40 times, and the rolling contact fatigue life has been increased by 40%. The rare earth bearing steel produced by relevant cooperative enterprises has excellent comprehensive mechanical properties.
“The successful development of super large diameter main bearings for shield machines has provided a good paradigm for tackling key problems of high-end basic components in China, and is a vivid embodiment of giving play to the advantages of the new national system and carrying out coordinated innovation in government, production, education, research and application.” Li Yiyi said.