Company News

 cold drawn seamless steel pipe

Company News

 cold drawn seamless steel pipe
Back to Results   |You are in :  Home  >  News  >  Company News

Treatment method for surface defects of cold drawn seamless steel pipe

Date:2022-03-10View:771Tags: cold drawn seamless steel pipe

After more than ten years of production and research by domestic manufacturers, high-precision cold-drawn seamless steel pipes for hydraulic (pneumatic) cylinders have played an increasingly important role in my country's hydraulic (pneumatic) industry. The hole quality requirements are high, and the cold drawn seamless steel pipe can only meet the requirements after honing. Therefore, the amount of honing reserved during cold drawing is very important to improve the production efficiency of the honing machine and reduce the production cost. To this end, we have carried out a special analysis and research on the surface quality of the inner wall of the cold-drawn seamless steel pipe.


seamless steel pipe


1. Inner wall surface defects of cold drawn seamless steel pipe:
The inner surface roughness of the high-precision cold-drawn seamless steel pipe is Ra≤0.8μm, and the dimensional accuracy of the inner diameter can reach H9~H10. Only in this way can the inner hole size of H7~H8 and the inner surface roughness of Ra≤0.2μm be guaranteed after honing. . In addition to the equipment accuracy of the honing machine, the main factors affecting the surface roughness of the honing pipe are the quality of the inner surface of the cold-drawn seamless steel pipe.

(1) pitting
After rough honing of cold-drawn seamless steel pipe, it can be found that there are many pit-like defects on its surface. If such defects are not ground, it will seriously affect the smoothness of the inner hole of the cylinder, and it is a waste product for the cylinder.

(2) scratches
Scratch defects are produced during cold drawing, and are generally a scratch along the axis of the steel pipe. There must be a honing allowance that exceeds the depth of the scratch to remove such defects and process a qualified cylinder.

(3) Not round
During the production of cold-drawn seamless steel pipe, the inner mold fixed on the core rod can float up and down, so the inner diameter is not as straight as the machined pipe. In addition, some hot-rolled pipes have a large difference in wall thickness with the same pipe. Due to the uneven deformation in the pipe during cold-drawing deformation, it is easy to produce out-of-round spots of cold-drawn seamless steel pipes. After the tube is honed, it will be found that there is a flaky surface in the inner hole that is different from other places in terms of reflectivity. If the grinding amount is small, even the phosphating layer during cold drawing is not ground here. Seriously affect the surface quality of the cylinder barrel.

2. Defect handling opinion:
(1) Cold-drawn seamless steel pipes (mild steel seamless pipe) are directly processed into cylinders, and the quality cannot be guaranteed. It is best to leave 0.2mm (wall thickness) for honing, and then process them after grinding.
(2) The pitting defect of the inner hole of the cold-drawn seamless steel pipe is the main reason that affects the surface quality of the inner hole of the cylinder.
(3) The pitting defect is produced by the hot-rolled tube, and cold drawing can reduce the depth of the defect but cannot eliminate the defect.
(4) Increase the amount of cold drawing deformation, optimize the hot-rolled tube blank, and clean the inner hole of the hot-rolled tube. It can improve the surface quality of the inner wall of the cold-drawn seamless steel pipe, reduce the honing allowance, reduce the honing cost, and improve the honing production efficiency.

  
close

We use cookies to offer a better browsing experience, analyze site traffic, and personalize content. By using this site, you agree to our use of cookies.

Accept
Decline