In the production of sinking rollers, minor defects such as scratches on the rollers may occasionally occur. How do these phenomena arise? What are the influencing factors?
Actually, there are many influencing factors. For example, in terms of equipment, there are generally the following reasons:
a. Regarding the mechanical structure of the sinking roller device, from the perspective of increasing friction, the type of grooves on the sinking roller surface should be considered first. There are two reasons for this. Firstly, zinc is a heavy metal with poor fluidity and high viscosity. During the high-speed movement of the strip steel and the sinking roller, a thin film of zinc liquid is easily formed between them, which acts as a lubricant, reducing the transmission friction between the strip steel and the sinking roller, which can easily cause scratching defects on the sinking roller. Therefore, the grooves must be conducive to the flow of zinc liquid between the strip steel and the sinking roller to prevent the formation of a sliding film of zinc liquid. Secondly, when designing the grooves on the sinking roller surface, it is necessary to start from a mechanical perspective to ensure that the sinking roller and the strip steel are in the optimal stress state, maximizing the transmission friction between them. Therefore, when designing the grooves on the sinking roller surface, the above two points must be considered.
b. The material requirements for the roller surface are also one of the influencing factors. Due to the special working position of the sink roller, the material of the sink roller surface should meet three requirements: 1. corrosion resistance, 2. hardness requirements, and 3. roughness requirements.
c. The influence of the sinking roller's self-weight. From a dynamic perspective, another important factor affecting the transmission of the sinking roller is its self-weight. Under normal production conditions, the sinking roller is subjected to the normal pressure of the strip steel, the friction between the strip steel and the sinking roller, the force between the bearing seat, and its own self-weight. According to the composition and decomposition of forces, the resultant force of the above four forces can be decomposed into radial normal 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.
d. The structural design requirements for the sinking roller device must address the axial fixation issue in its design to prevent axial sliding of the sinking roller during rotation. Especially for strip steel with poor plate shape, such as wedge-shaped or unevenly thick strip steel, when they come into contact with the strip steel for transmission, the uneven force between the strip steel and the sinking roller can easily cause the strip steel to deviate, leading to axial sliding on the sinking roller and resulting in scratch defects on the sinking roller. The gap between the bearing and the bearing seat of the sinking roller should be as small as possible; an excessively large gap can easily cause radial runout of the sinking roller.