- In actual operation, there are many factors that will affect the assembly of the idler ring. If the assembly operation is not proper, it may cause the production problems such as idler burst, idler loosening and cone sleeve breakage. Therefore, the factors affecting idler ring assembly are classified and analyzed, and a reasonable loading and unloading pressure range of idlers is established, which can effectively prevent the occurrence of idler burst, idler loosening, cone sleeve breakage and other accidents.
- Analysis of influencing factors: According to the structure of the roller ring of high speed wire mill, the factors affecting assembly are analyzed. Mounting size: The geometry of the roller ring, cone sleeve, roller shaft, roll changer and roll press has a direct impact on the roller ring assembly and is a more critical factor.
Roller ring
- The roller ring is made of WC material with HRC hardness of 83, which is a kind of high wear-resistant material. The center hole of the roller ring is in contact with the outer ring of the cone, so the fitting tolerance between the center hole of the roller ring and the cone sleeve is a very important parameter.
- The inner circle of the cone sleeve is in direct contact with the roller, and interference fit is adopted. The taper of the circle in the cone sleeve should match the taper of the roller shaft and should not exceed the tolerance range. Otherwise, it will affect the contact area between the inner ring of the cone sleeve and the roller shaft, and the contact surface should be greater than 70%. The roller puller and the roller press of the roller changer are matched with the four ears of the cone sleeve to complete the loading and unloading of the roller through the set pressure value. The size of the drum machine and drum press and the cone lug should match.
Managing Hardness and Temperature for Smooth Roller Assembly
- Surface hardness: the inner ring of the cone is in direct contact with the roller shaft, and interference fit is adopted. The hardness of the cone sleeve and the roller shaft should match. The HRC hardness of the roller ring cylinder is usually 55~65. If the hardness of the cone sleeve is too high, it is not conducive to the protection of the roller shaft. If the hardness of the cone sleeve is too low, the cone sleeve will produce plastic deformation, which can not ensure the normal rolling torque requirements, resulting in the cone sleeve slip, roll loose and other accidents, It is necessary to control the hardness of the cone sleeve within a certain range, and it should be 10 to 20 less than the hardness of the roller.
- Assembly temperature: If the temperature difference between the roller ring, the cone sleeve and the roller ring shaft is too large, due to the different coefficient of thermal expansion, the roller ring, the cone sleeve and the roller ring shaft will have uneven forces, resulting in easy failure during the loading and unloading of the roller. The normal rolling temperature of the roller is 50℃~60℃, and the temperature of the roller ring, cone sleeve and roller is required to be about 25℃ when loading and unloading the roller.
Therefore, it is necessary to ensure that the cooling water of the roller ring is sufficient, and the pressure and temperature are stable, so as to ensure a good cooling effect and avoid the high temperature of the roller shaft due to the high temperature of the roller ring. After stopping the rolling, it should be idled for 3 minutes to ensure that the temperature of the roller is reduced to about 25℃.