Aoyu Kexin Group undertook the repair of the seal of the seal of the core part of the “Hitachi†shield machine imported from Japan by the Beijing Urban Construction Group. According to the statistics of relevant departments, the wear of the sealing position of the shield machine drive shell is the biggest problem that restricts the use of the unit. Previously, there were no such repair cases at home and abroad.
The shield machine, the full name is the shield tunneling machine, is a special construction machine for tunneling. Widely used in subway, railway, highway, municipal, hydropower and other tunnel projects. The introduction of the shield machine has a history of 180 years, starting in the UK and developing in Japan and Germany. The basic working principle is that a cylindrical steel component is pushed forward along the axis of the tunnel to excavate the soil. The manufacturers of shield machines are mainly Herrenknecht of Germany, Robbins of the United States, Maitong of France, Mitsubishi Heavy Industries of Japan, Kawasaki Heavy Industries, and Hitachi. The development and production of China's shield machine is still in its infancy. About 90% of the shield tunneling machines in China rely on imports. The subway shield machines of European and Japanese companies are monopolized in the Chinese market. Its market price is between 30 million yuan and 70 million yuan.
At the end of 2004, Beijing Urban Construction Group invested USD 3.8 million to purchase the first Hitachi EPB Φ6170 earth pressure balance shield machine, and participated in the 10-11 section of Beijing Metro Line 4, designed to use 8 kilometers, and the actual use is only 3.8 kilometers. There was a serious strain in the drive housing seal and the whole machine was smashed. The outer diameter of the drive housing is 4.5 meters and the net weight is 19 tons. If the processing price of the new product is 30,000 yuan per ton, the construction period is about 3 months; if you purchase 2 sets of the same model, it can be repaired free of charge (the current price of this model is 35 million yuan), but the original drive must be destroyed. The case of the main structure of the outer casing is repaired without warranty.
In January 2009, Aoyu Kexin Group officially intervened in the research on the sealing technology of the sealing shell of the Hitachi shield machine. Through multi-party argumentation, it is believed that the composite application Aoyu Kexin repair technology can complete the repair project without destroying the main structure. During this period, the same problems occurred in the same type of equipment of the subway foundation company affiliated to the group, and the area of ​​the injury was larger than the previous one. The Urban Construction Group decided to commission two equipments at the same time to be repaired by Aoyu Kexin Group.
On May 3, 2009, the press conference of the completion of the "Hitachi" shield tunneling machine drive shell repair project was held. The construction site of Beijing Aoyu Kexin Group was full of joy and applause! With the closing of the press conference, the two shield machine drive shells were officially delivered to Beijing Urban Construction Group.
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