Causes and solutions of cold rolling seam print defects, cold rolling technology
The imprint defect is a defect that will appear after the production of various cold rolling processes. What are the reasons for this defect?
Each process of cold rolling will produce stubbing defects. The closer the unit is to the finished product (especially the post-annealing process), the more likely it is to produce this defect. The main reasons are as follows:
Hot rolling mill; stem mark defect; coiling
Realed product：rolling mill rolls
1. Reasons for coiling
1) The inner diameter strip is folded during coiling: the strip head is slightly tilted when the strip is threaded. This part is not cut off or flat before coiling, resulting in creases after coiling, which are transferred layer by layer.
2) The segments of the coiler are not smooth: after the reel is expanded, there will be gaps between the segments, and the stress concentration at the edges is serious. The concentrated stress acts on the strip steel core to form a stalk.
1) The belt threading speed should not be too fast, controlled at 30m/min, the tension cannot be set too high during winding, and the belt winding aid must be run to the limit before winding.
2) Regularly maintain the fan-shaped block to ensure that the fan-shaped block is smooth, otherwise it will not be used on the machine.
2. The origin of the raw material
1) The hot rolling mill did not change the rolls in time when rolling the cold-rolled raw materials, which caused excessive wear of the rolls, causing the cross-section of the cold-rolled raw materials to form bulges like “cat ears”. After cold-rolling and annealing Strip steel passes through coiling, the defects are magnified layer by layer, and the imprint defects are formed on the outer ring of the steel coil:
1) The hot rolling mill should promptly replace the rolls in accordance with the rolling specifications, and check the crown status of the strip through the crown meter. If abnormalities occur, the rolls should be replaced in time.