With the rapid development of machine tool industry and the continuous improvement of processing automation level, the requirements for the durability of metal cutting tools is increasingly high. In order to improve tool durability and improve workpiece processing conditions, the main shafts are all processed by external large flow cooling. Therefore, the main shaft seal structure design is particularly important. The main purpose of the sealing device is to prevent the external moisture, cuttings, dust and other substances from invading the bearings, and ensure that the lubricant in the bearing does not leak.
The form of main shaft seal can be divided into two categories, namely, contact seal and non-contact seal. The contact seal has a sealing effect by rubbing the ends of the synthetic rubber, synthetic resin, felt, leather and other materials with the rotating body. As the sealing elements are directly in touch with the rotating body, and this kind of rub will cause the wear of the sealing elements and generate heat during the operation of the main shaft. Therefore, this type of mechanical seal is suitable for main shafts with middle and low rotation speed. The non-contact seal has a sealing effect through the small clearance or centrifugal force between the rotating body and the non-rotating body. Because the rotating body is not contacted with the seal, this kind of sealing structure will not cause rub and heat and is suitable for main shafts with middle and high rotation speed.