What are the influencing factors of sinking roller scratches

In the production of sinking rolls, some small defects sometimes appear, such as scratches on sinking rolls, etc., so how does this phenomenon happen? What are the influencing factors?
In fact, there are many influencing factors. For example, in terms of equipment, there are generally the following reasons:
a. The mechanical structure of the sinking roller device, from the perspective of increasing friction, the type of groove on the surface of the sinking roller should be considered first. There are two reasons for this. The first point is that zinc is a heavy metal, and its zinc liquid has poor fluidity and high viscosity. During the high-speed movement of the strip steel and the sinking roll, it is easy to form a A layer of zinc liquid film plays a certain lubricating effect, reduces the transmission friction between the strip steel and the sinking roll, and easily causes the sinking roll to scratch defects. Therefore, the groove must be conducive to the flow of zinc liquid between the strip steel and the sinking roll, so as to prevent the formation of sliding film of zinc liquid. The second point is to start from the mechanical point of view when designing the grooves on the surface of the sinking roll, so that the sinking roll and the strip are in the best stress state, and the transmission friction between the two should be improved as much as possible. Therefore, the above two points must be considered when designing the surface groove of the sinking roller.
b. The requirements for the material of the roll surface are also one of the influencing factors. Due to the special working position of the sinking roller, the material of the sinking roller surface should meet three requirements: 1. Corrosion resistance, 2. Hardness requirements, 3. Roughness requirements.
c. The influence of the self-weight of the sinking roller. From a dynamic point of view, another important factor affecting the transmission of the sinking roller is the self-weight of the sinking roller. In the normal production state, the sinking roll is subjected to the normal pressure of the strip, the friction between the strip and the sinking roll, the force between the bearing seat and its own weight. It can be seen from the synthesis and decomposition of the force that the resultant force of the above four forces can be decomposed into radial positive pressure and radial tangential force. The radial tangential force is the driving force for the rotation of the sinking roller, and its magnitude directly affects the rotation of the sinking roller. Condition.
d. The structural design requirements of the sinking roll device, the design of the sinking roll device must solve the problem of axial fixing to prevent the sinking roll from sliding in the axial direction during the rotation process; especially for some strips with bad shape, such as wedge, For strip steel with uneven thickness, when they are in contact with the strip steel, the force between the strip steel and the sinking roller is uneven, which will easily cause the strip steel to deviate, resulting in axial sliding of the strip steel on the sinking roller, resulting in sinking Roller scratch defects. The gap between the bearing and the bearing seat of the sinking roller should be as small as possible; if the gap is too large, it will easily cause the radial runout of the sinking roller.