Adjustment of Welding Roller for ERW Carbon Steel Pipe

In the production of erw carbon steel pipe, the shape of the joint of the tube directly affects the quality of the weld, in which the parallelity of the welded joint is particularly important. In the pipe joint welding process, mainly by adjusting the amount of roller on the roll and the gap between the two rollers to ensure the degree of parallel fit.

1. Features of the welding of the squeeze roller

The size of the squeeze roller on the extrusion extrusion frame is about 10% greater than that of the other squeeze rollers. Therefore, there is a gap between the outer roller surface of the upper squeeze roller and the ideal circular cross section of the steel pipe, Followed by the gap ". In the actual molding, the steel pipe section can not be the ideal circular. Under normal circumstances, due to the deformation of the edge of the strip is not sufficient, the section is easy to peach-shaped, if not adjusted will form a welded butt joint non-parallel docking, seriously affecting the quality of the weld. If the upper squeeze roller and the other squeeze rollers use the same bar diameter, when the V-shaped joint is removed by adjusting the reduction amount of the upper squeeze roller, the outer roller surface of the upper squeeze roller will be strongly pressed against the steel pipe On the surface, easily lead to surface scratches, and the formation of a serious V-shaped joints. Therefore, the "heel gap" is set according to the actual characteristics of the tube forming, through the upper squeeze roller to adjust the amount of pressure to effectively eliminate the V-shaped joint phenomenon.

2. Adjustment method of upper squeeze roller
When the position of the squeeze roller is set according to the standard hole, if it is found that the molded joint is V-shaped, the reduction amount of the upper squeeze roller can be adjusted in the range of "heel gap". The limit of the amount of pressure on the upper squeeze roller is such that the outer roll surface of the upper squeeze roll causes a shallow indentation on the surface of the steel pipe. In accordance with experience, when the pressure to reach this limit, even if the higher strength of the pipe, usually can also be formed into a flat shape joint. In applying this experience, the gap between the two upper squeeze rollers must be set exactly in accordance with the design value. The change in this gap will directly cause "heel gap" changes. If the roll is not set to the design value for each time, the adjustment of the hole is difficult to achieve reproducibility.

3. Method of confirming the butt joint state of forming joint
It is the most accurate way to confirm the weld profile of the weld area. The method not only can determine the joint state, but also can determine the welding extrusion and welding output power is reasonable or not. In order to facilitate the observation of the streamline, the specimen shall be taken before the weld heat treatment. If the upper part of the weld metal line angle is basically symmetrical, it can be judged that the joints of the joints are parallel. The difference between the flow direction angles of the upper and lower symmetrical parts is usually limited to five degrees, and the "waist drum" shape of the heat affected zone should be substantially symmetrical. The easiest way to confirm the scene is to compare the shape and size of the inner and outer burrs after welding. If the seam is type I, the size and shape of the inner and outer burrs are basically the same. But this method can not be quantified, only as a general judgment.