Nation makes new progress in manufacturing TBMs

The main bearing of China's first domestically produced super-large shield tunnel boring machine (TBM) has passed a professional review by Chinese academicians and experts.

As a major piece of equipment for infrastructure construction, known as "the king of construction machinery" in the world, the completion of the main bearing is a milestone as China strives to enhance technology self-reliance.

Experts who participated in the review said that the main bearing has reached the advanced level of imported products, with some indicators already reaching the world's standards in the world, according to media reports.

The main bearing, dubbed the "breaker," has a diameter of 8.01 meters and weighs 60 tons. It is the largest and heaviest single body part developed in China for TBMs.

The "breaker" can be applied to ultra-large shield machines with a diameter of 16 meters, with a designed service life of more than 10,000 hours or 416 days, and a sustainable excavation length of more than 10 kilometers.

Jiangsu-based CCCC Tianhe Machinery and Equipment Manufacturing Co (CCCC Tianhe), a subsidiary of China Communications Construction Co (CCCC), and the Institute of Metal Research of Chinese Academy of Sciences, jointly developed the "breaker."

"By realizing independent production of main bearings, we can manufacture shield machines completely on our own," said Qian Qihu, an academician of the Chinese Academy of Engineering.

Many indicators of "breakers" include fatigue strength, metallurgical technology, quenching technology and assembly accuracy, and they all have surpassed the advanced level of similar imported products, and some indicators are already world-leading, according to Qian.

From the perspective of industrial security, China needs to come up with more advanced substitutes, especially for major equipment such as the TBMs, Liang Zhenpeng, an industry analyst, told the Global Times on Sunday.

The launch of the self-developed main bearing means that China has the independent intellectual property rights of the core components needed for making TBMs, which will shorten construction periods and save costs on tunnel projects.

It will also significantly contribute to the security and controllability of the national supply and industry chains, Liang said.

CCCC Tianhe has independently developed shield machines such as the 15.03-meter ultra-large diameter TBM called "Zhenxing" and China's first synchronous TBM known as "Xingye." The domestic parts supply rate has reached 98 percent.

The experts' review shows that the nation has fully mastered integrated technologies ranging from independent design to installation and commissioning, said Zhang Boyang, head of CCCC Tianhe.

Such breakthroughs have opened up the "last mile" toward national production of super large diameter shield machines, and the price is only about 70 percent of imported main bearings, Zhang said.

China has been ramping up efforts toward self-sufficiency and self-reliance. The 14th Five-Year plan (2021-25), issued by the State Council, the cabinet, focuses on enhancing competitiveness in core industries by improving the supply of basic software and hardware, core electronic components, key materials and production equipment.