In the production of furnace rolls, some small defects, such as sinking roll scratches, sometimes occur. 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 settling roll device should be considered from the point of view of increasing friction, and the groove type on the surface of the furnace roll should be considered first. There are two reasons. Zinc is a heavy metal with poor fluidity and high viscosity. During the high-speed movement of the strip and the underwater roller, a zinc film is easily formed between the strip and the underwater roller, which plays a certain lubricating role and reduces the transmission friction between the strip and the water roller, which is easy to cause the underwater roller. Scratch defects. Therefore, the grooves must facilitate the flow of molten zinc between the strip and the furnace rolls and prevent the formation of a sliding film of molten zinc. Secondly, when designing the grooves on the surface of the latent roll, it is necessary to make the latent roll and the strip in a perfect stress state from a mechanical point of view, and to improve its transmission friction as much as possible. Therefore, the above two points must be considered when designing the grooves on the surface of the sink roll.
b. The requirement of the roll surface material is also one of the influencing factors. Due to the special working position of the furnace roll, the material on the surface of the settling roll should meet three requirements: 1. Corrosion resistance 2. Hardness 3. Roughness.
c, From a dynamic point of view, another important factor affecting the drive of the sinker roll is the weight of the sinker roll. Under normal production conditions, the submerged roller is subjected to the positive pressure of the steel belt, the friction between the steel belt and the submerged rollers, the force between the steel belt and the bearing housing and its weight. From the synthesis and decomposition of forces, it can be seen that the resultant force of the above four forces can be decomposed into radial pressure and radial tangential force. The radial tangential force is the power of the settling roll rotation, and its size directly affects the settling roll rotation.
d. According to the structural design requirements of the furnace roller device, the problem of axial fixation must be solved to prevent axial sliding during rotation, especially for strips with poor shapes such as wedge-shaped strips with uneven thickness, when they are in contact with the strips for transmission. , the uneven force between the strip and the dipping roll easily leads to strip offset, resulting in axial slip on the dipping roll and scratching defects on the dipping roll. The gap between the sink roller bearing and the bearing seat should be as small as possible, and if the gap is too large, it is easy to cause the radial runout of the furnace roller.