Measures to prevent milling defects of spiral seam submerged arc welded steel pipes

1. Reasonable selection of milling process and parameters:

Reasonable selection of milling process according to actual production conditions. Under the condition of ensuring production, try to use a single milling process and select an I-type groove, to reduce milling defects and make it easy to process. Selecting a suitable working width can not only reduce the probability of de-milling but also maximize the life of the blade, thereby improving the processing accuracy. Theoretically, the milling amount of 8~10mm is generally selected, that is, the milling working width = the narrowest actual original plate width of 8mm. However, one thing needs to be pointed out if the narrowest width deviation of the steel plate is large during production, it is not appropriate to adopt a fixed milling width. For example, it is often encountered that a batch of steel pipes is produced using steel coils from two steel mills. Generally speaking, the width deviation of steel coils from different steel mills is large. At this time, to improve the yield rate and reduce the milling amount of the blade, a flexible adjustment method should be adopted. A reasonable selection of groove depth according to the thickness of the steel plate gives it a large room for maneuvering.

2. Strengthen the control of steel plates to ensure the quality of steel plates:

Strengthen the leveling control of the leveling machine to ensure that the flatness of the steel plates is consistent and prevent the steel plates from entering the milling machine with "wave bends"; strengthen the control of material discharge and vertical rollers to try to eliminate the influence of the "crescent bend" of the original plate and prevent the generation of artificial "crescent bends".

3. Standardize the use of the milling machine and the replacement of milling blades:

The milling machine must be lubricated and maintained regularly to ensure the integrity and stability of the equipment. The milling blade is the only consumable in the milling machine. Almost every work shift needs to be replaced. The quality of the blade is crucial to the milling quality. Choosing better blades can reduce the number of stops, not only reduce arc breaking, and improve the one-time pass rate, but also improve the yield rate. Therefore, it is necessary to select coated blades with good wear resistance and heat dissipation performance and replace them in time and regularly. It should be noted that the milling cutter disc pursues an overall effect. If only some blades are replaced, it will cause "metal wire" defects and increase the working intensity of other blades, thereby reducing the service life of the overall blade. Therefore, all blades must be replaced when changing the blade.

4. Flexible adjustment of the milling machine:

Under certain circumstances, the milling machine can be flexibly adjusted to suit different situations. For example, when the working width deviation of the steel plate is 1~3mm, it generally does not affect the forming quality; when the edge of the steel plate deviates from the delivery line by 1~3mm, it can also be controlled. Therefore, when the steel plate cannot be controlled and is about to be de-milled, it can be controlled by fine-tuning the headstock. Another situation is that if the width of some steel coils does not exceed the standard, the working width of the milling machine can be fine-tuned to reduce the amount of blade milling and extend its service life.

5. Other methods:

Some relatively simple equipment or methods can be used to eliminate some milling defects. For example, for the slender "metal wire" defect of the steel plate, a simple wire brush can be used to "sweep it away".