Tube Mill Fault Analysis——Squeeze Roller Mechanism Scratches

(1) The hole type does not match

There are two-roller, three-roller and four-roller weld seam extrusion structures. As long as the combined hole shapes do not match, it is easy to cause scratches on the surface of the tube blank, especially the two-roller structure.

There are many factors that cause the shape of the hole to be inconsistent. Taking the two-roller structure as an example, such as bearing damage; axial movement of the rollers; different shapes and sizes of the holes; different heights and positions of the two rollers; shaft bending and unstable assembly, etc. .

(2) Height mismatch

The lower edge of the hole of the squeeze roller should be consistent with the height of the rolling line, while the height of the guide roller is determined by the wall thickness of the tube blank.

If the height of the guide roller 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. Scratches are more likely to occur.

(3) Insufficient extrusion force on the extrusion roller

Especially for the extrusion roller device with two-roll structure, when the upper extrusion force is insufficient, the roller shaft will have an upward elevation angle under the tension of the tube billet, making the green R rounded corner of the edge of the pass protrude. Thereby causing scratches on the lower part of the tube blank.

When the extrusion roller pass R fillet sharpens, it will aggravate the occurrence of scratch accidents.