Long lap welding

4.Large squeezing force

Overlap welded pipes caused by excessive extrusion force generally occur in the production of thin-walled pipes, and rarely occur in the production of ordinary thick-walled pipes. This is because in the production of thin-walled tubes, due to the poor rigidity of the tube blank, once the extrusion force is too large, the width of the tube blank can not be accepted after too much margin in the hole pattern, and it will be Space movement forms lap welding. Therefore, in the design of the pass, the appropriate pass radius and roll gap should be selected according to the different tube wall thickness, and at the same time, the amount of extrusion should be adjusted appropriately.

5.The guide roller is tilted

Under normal circumstances, the guide roller should be in a horizontal position. In order to better control the welding seam, the guide roller can be tilted. If the inclination angle is too large, the extension of the guide ring will be large. With the rotation of the guide roller, the roller ring will press the edge of the tube blank to deform abnormally, especially when the thin-walled tube is produced, it is easier to promote the lap welded tube. produce. Often the large tilt adjustment of the guide roller is because it cannot well control the direction of the pipe seam. Therefore, when the guide roller has a large hole shape, it is necessary to replace the new roller in time, check and adjust immediately when the center is not correct, and try to avoid large tilt adjustments.

6.The bottom diameter of the guide roller is different

If the bottom diameters of the two holes of the guide roller are not the same, the problem of lap welded pipes is also easy to occur, especially in the production of thin-walled pipes, this phenomenon is more likely to occur. When the machine is stopped for inspection, you can feel whether the welding seam of the welding V-shaped zone is smooth by touching it with your fingers. Of course, as long as we strictly control the quality of the rollers, this lap welding phenomenon can be overcome.