Seamless tube forming

According to different forming methods, seamless tube can be divided into two types: extruded and cold drawn. 

1. Hot rolling (extrusion): round billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → straightening → hydraulic test (or flaw detection) → marking → the raw material for the seamless tube in the warehouse is a round tube blank. The round tube blank is cut into a blank of about 1 m in length by a cutting machine, and sent to the furnace for heating through a conveyor belt. The billet is fed into a furnace and heated to a temperature of approximately 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is a key issue. After the round billet is released, it is subjected to a through-hole punching machine.

The more common perforating machine is a conical roller punching machine. This perforating machine has high production efficiency, good product quality, large diameter of perforation and can wear a variety of steel types. After perforation, the round billet is successively rolled, rolled or extruded by three rolls. After extrusion, the tube should be sizing. The sizing machine is rotated at a high speed by a conical drill bit into a steel core to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter of the sizing machine drill bit. After the steel pipe has been sized, it enters the cooling tower and is cooled by water spray. After the steel pipe is cooled, it is straightened. After the steel pipe is straightened, it is sent to a metal flaw detector (or water pressure test) by a conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, bubbles and other problems will be detected. After the quality inspection of the steel pipe, it must be carefully selected by hand. After the quality inspection of the steel pipe, the paint is sprayed with the number, specification, production batch number, etc. It is hoisted into the warehouse by a crane. :

2. Cold drawn: round tube blank → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening →Hydraulic pressure test (inspection) → mark → storage. 

The difference begins with the fourth step. After the round billet is hollowed out, it is required to start and anneal. After annealing, it is acid washed with a special acidic liquid. After pickling, apply oil. This is followed by a multi-pass cold drawing (cold rolling) of the blank tube, followed by a special heat treatment. After heat treatment, it is straightened. After the steel pipe is straightened, it is sent to a metal flaw detector (or water pressure test) by a conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, bubbles and other problems will be detected. After the quality inspection of the steel pipe, it must be carefully selected by hand. After the quality inspection of the steel pipe, the paint is sprayed with the number, specification, production batch number, etc., and is hoisted into the warehouse by the crane.