Weld quality failure of high frequency longitudinal welded pipe mill equipment
Author： Source：TENYES ELECTROTHERMAL EQUIPMENT CO.,LTD. Date：2020-09-29
Common faults of welding machine
There are relatively many faults in welding machines, and the causes of the faults are also complex, often one result is caused by many reasons, or one reason can cause several results. Some failures are tricky to handle. Let's give a brief account of the scratch accident.
The pipe blank scratch in welding machine is mainly caused by two parts, one is the guide mechanism, the other is the extrusion welding mechanism.
1) the scratch of the guiding mechanism
Scratches on the guide parts generally occur on both sides of the pipe blank. If the guide structure with guide sleeves is not adjusted properly, the upper and lower surfaces of the pipe blank will also be scratched by friction, which is characterized by large wound surface and strong continuity. The main reason is that the height position of the guide sleeve is incorrect, or after the upper and lower guide roller bearings are damaged, the pipe blank can not be well controlled, and it is formed after friction with the guide sleeve. In addition, when the guide roller deviates too much from the rolling center line, and the relative difference between the axes of the guide sleeve and the guide roller is too large, both sides of the tube blank will be scratched.
2) Scratch of extrusion welding mechanism
Scratches caused by the extrusion roller mainly occur at the bottom of the tube blank for the following reasons:
1. Weld extrusion structures with inconsistent hole patterns are two-roll, three-roll and four-roll. As long as the combined hole patterns are inconsistent, it is easy to scratch the surface of pipe blank, especially the two-roll structure. There are many factors that cause the hole pattern inconsistency, taking the two-roll structure as an example, such as bearing damage; Axial movement of roller; Pass sizes are different; The height and position of the two rollers are different; Shaft bending and unstable assembly, etc.
2. The lower edge of the hole pattern of the highly matched extrusion roller should be consistent with the height of the rolling line, and the height of the guide roller is determined by the wall thickness of the tube blank. If the height of the guide roll is reduced to a certain limit, the edge fillet of the extrusion roll pass will scratch the bottom of the tube blank, especially after the R fillet of the extrusion roll pass is sharpened, the scratch is more likely to occur.
3. The extrusion force on the extrusion roller is insufficient, especially in the extrusion roller device with two-roller structure. When the extrusion force is insufficient, under the tension of the tube blank, the roller shaft will have an upward elevation angle, which will make the round corner of the pass edge R protrude, thus causing scratches on the lower part of the tube blank. When the rounded corners of the extrusion roll pass R are sharpened, the scratch accident will be aggravated.