China used pipe welding machines often consider many key technologies when producing precision welded pipes, such as ① quality requirements for raw materials, ② welded pipe forming process, ③ formation and removal of weld burrs, ④ weld heat treatment, ⑤ non-destructive testing, ⑥ correct Equipment requirements for welded pipe unit. For this reason, we introduce the formation and removal of weld burrs which should be considered in the production of precision welded pipes.

Precision welded pipes are more accurate in geometric dimensions than general welded pipes, and the welds and inner and outer surfaces are of good quality, and the wall thickness is uniform. It can be used in equipment components directly or with a small amount of processing. It is widely used in chemical, textile machinery, aviation, instrumentation, automotive and other sectors.

When the welded pipe is made by the China used pipe welding machines, weld burrs will appear. So let's explore the formation and removal of weld burrs. Through the skin effect and proximity effect of the high-frequency current, the current is concentrated at the welding seam and heated to a molten state. When the squeezing roller is pressurized laterally, the squeezing force will cause the excess metal and oxide to accumulate on the upper part of the welding seam. The outer surface burr is formed; under the combined action of squeezing force and gravity, other excess metal and oxides sag on the inner side along the axis of the steel pipe to form inner burrs.

The width of the burr is usually about 0.5~3mm, and the height of the internal burr is uneven, usually 0.2~0.6mm, and the individual height can reach more than 1mm. The outer burr is generally removed by planing, while the inner burr has a small space in the steel pipe, which increases the difficulty of removal technology. Due to the existence of internal burrs, cracks, folds or scratches will be formed on the inner surface of the steel pipe when the steel pipe is subjected to cold drawing or cold rolling finishing. Therefore, for precision welded pipes, the internal surface quality requirements cannot be met without removing the internal burrs, and subsequent processing cannot be performed.

The external burr removal device has a planing knife and two planing knives. One planing knife needs to be stopped to change the knife, and two planing knives are used to remove the burrs, and the knife change does not need to be stopped. The technique of removing internal burrs is very difficult. Because the special device for removing internal burrs is inside the steel pipe, the working environment is very poor, invisible and intangible. It is affected by the accuracy of the strip steel, the accuracy of the unit equipment, the forming process, and the shape of the weld. Not guaranteed.

Removal of internal burrs is usually done on a continuous welded pipe production line, but off-line methods can also be used. There are mainly the following methods to remove internal burrs during the production of precision welded pipes with China used pipe welding machines:

Cutting method: This method uses a fixed blade or a rotating cutting head to cut the burrs.

Rolling method: This method uses a rolling device extending into the tube to plastically deform the inner burr and achieve the effect of reducing the height of the inner burr.

Oxidation method: At the beginning of steel pipe welding, use a vent nozzle to inject an oxygen stream into the inner welding seam, and use the welding residual heat of the welding seam to accelerate the oxidation of the inner burr and fall off under the air flow.

Drawing method: When the steel pipe passes through the mold, the burr inside the steel pipe is removed under the action of the annular blade of the floating plug.

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