How can seamless steel tubes be produced?
Seamless steel tubes are made of ingots or billets made by piercing and are then made by hot rolling, cold rolling or cold casting. Seamless steel tube plays an important role in the steel tube industry of our country. According to incomplete statistics, China's existing seamless tube production enterprises about more than 240, seamless steel pipe units about more than 250 units, with an annual output capacity of about about 4500000 tons. From the caliber, 35% of phi 76, less than phi 159-650, accounting for 25%. From the species point of view, the general use of 1 million 900 thousand tons of pipe, accounting for 54%; oil pipe 760 thousand tons, accounting for 5.7%; hydraulic props, precision pipe 150 thousand tons, accounting for 4.3%; stainless steel pipe, bearing tube, automobile tube 50 thousand tons, accounting for 1.4%.
Tube mill, round tube billet, heating, perforation, three roll cross rolling, rolling or extrusion, removal of pipe, sizing (or reducing diameter), cooling, straightening, water pressure test (or flaw detection), marking, storage, cold rolling and hot rolling. Generally cold rolling, because of high accuracy.
After extrusion to remove pipe sizing. The sizing machine passes through the cone bit and rotates into the steel embryo at high speed to form a steel tube. The inner diameter of the steel pipe is determined by the outside diameter and length of the sizing machine. When the steel tube is fixed, it enters the cooling tower and is cooled by spraying water. The steel tube is straightened after cooling. After straightening, the steel pipe is sent to the metal flaw detector (or water pressure experiment) by the conveyor belt for internal inspection. If there are cracks in the steel pipe, bubbles and other problems will be detected. Steel pipe quality inspection, but also through strict manual selection. After the quality inspection of the steel pipe, spray with the paint on the number, specifications, production batch number and so on. The crane is hoisted into the warehouse.
The material of rolling seamless tube is round tube blank, and the billet is processed by cutting machine to grow about 1 meters, and sent to the furnace by conveyor belt. The billets are heated into a furnace and the temperature is about 1200 degrees celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is a key problem. When the round billet is released, it should be punched through the pressure piercer. The most common punching machine is a cone roll piercer, which has high production efficiency, good product quality, large perforation and expanding diameter, and can be used in various steel grades. After the perforation, the round tube blank has been successively rolled, rolled or squeezed by three rollers.
