1 Axial movement of extrusion roll
Due to the unstable positioning of the extrusion roll and the extrusion roll shaft, as well as the gap caused by the loose fit of other parts during assembly, the extrusion roll will have axial movement and radial swing, and then the pass of the extrusion roll will not match, resulting in overlap welding.
2 Bearing damage
When the bearing is damaged, the normal position of the extrusion roll will be damaged. Take the two-roll extrusion roll device as an example. Generally, two sets of bearings are installed in the extrusion roll. When one set of bearings is damaged, the extrusion roll will lose control, and the weld will be higher, resulting in overlap welding. During the production operation, we can observe the swing of the extrusion roll. When the upper bearing is damaged, the swing amplitude of the roller is larger, and when the lower bearing is damaged, the swing amplitude of the roller is smaller, which is also related to the degree of bearing damage. After the bearing of the guide roller is damaged, it can not only control the weld direction of the tube blank well, but also the guide ring may cause pressure damage to the edge of the tube blank after the bearing is damaged, resulting in the change of the weld height, and slightly inappropriate will cause overlap welding accidents.
