Processing technology of alloy steel tube
- Aug 07, 2018 -

In order to ensure uniform thickness of the steel pipe, the center of the tube blank must be aligned when piercing. Therefore, before extrusion, the ingot or billet needs to be shaped; the round billet must be centering before cross rolling. The aim of centering is to aim at the axis of the tube in the head and nose of the perforation, prevent the perforation from wearing off and reduce the uneven thickness of the front wall of the capillary, and improve the two bite conditions of the oblique piercing, so that the perforation process is carried out smoothly. The methods of centering are cold and hot. Hot centering is to punch the billet in hot state with compressed air or hydraulic pressure after heating, and the equipment of alloy steel pipe is set at the front of the perforator. This method has high efficiency, no metal consumption, simple equipment and wide application. At the same time, the size of the centering hole can be obtained because of the shape of the punch and the shape of the head nose. But over the past ten years, with the improvement of technology and equipment, the number of units equipped with thermal centering is less and less. Some foreign manufacturers believe that the perforated rotary bite has a certain self alignment effect on the tube billet. If the piercing piercer before and in the background is better, the diameter of the tube billet is not more than 1.5mm. As long as the length of the roll body is properly increased, the wall thickness uniformity of the perforated pipe can be ensured, and it is not sure. This statement has been approved by many manufacturers in China, especially in small and medium sized units, there is basically no heat setting machine. In recent years, most of the new units in China have not used hot centering, including many large diameter production lines. In addition to the above statement, the heat setting machine will increase the investment of the equipment, and the heat setting process will reduce the temperature of the tube billet of the alloy steel tube, and increase a certain energy consumption is one of the reasons.

For the medium and large diameter thick wall tubes still need to be centering. Cold centering means drilling holes on special machine tools before heating the tube. It is characterized by high dimensional accuracy of centring holes, but loss of part of alloy rigid tube metal and low efficiency. Therefore, cold centering used to be used only when producing alloy steel pipes and important use steel pipes. However, with the improvement of product quality in the market, the proportion of cold centering is gradually expanding with the increase of the efficiency of cold centering equipment. Cold centering is not only to prevent the uneven thickness of the front end wall of the capillary, but also to reduce the ear of the tail of the capillary tube, cold centering is also adopted for the tail of the tube blank.