Thermal expansion and contraction of seamless black steel pipe

The heat-expandable seamless black steel pipe is what we often call the heat-expandable pipe, and the steel pipe with low density but strong shrinkage can be referred to as the heat-expandable pipe. A roughing and finishing process for enlarging the diameter of a pipe by skew rolling or drawing. Increasing the outer diameter of the steel pipe in a relatively short period of time can produce non-standard and special-shaped seamless pipes with low cost and high production efficiency, which is a trend in the development of the international pipe rolling field.

The raw material for rolling the seamless tube is a round tube blank, which is cut into a billet with a length of about 1m by a cutting machine, and is sent to the furnace for heating through a conveyor belt. The billets are fed into a furnace and heated to a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is a critical issue.

After the round billet is demolded, it passes through the punching machine. The more common punching machine is the tapered roller punching machine. The punching machine has high production efficiency, good product quality, large perforation diameter, and can wear a variety of steel grades. After perforation, the round billet is rolled, rolled or extruded in turn by three rolls. After extrusion, the pipe should be sized. The sizing machine rotates the conical drill bit into the steel core at high speed to form the steel pipe. The inner diameter of the steel pipe is determined by the outer diameter of the drill bit of the sizing machine.

After the steel pipe is shaped, it enters the cooling tower and sprays water for cooling. After the steel pipe has cooled, it is straightened. After the steel pipe is straightened, it is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks inside the steel pipe, problems such as air bubbles are detected. After the steel pipes have been inspected for quality, they must be carefully selected by hand. After quality inspection, the steel pipes are sprayed with paint, sprayed with serial numbers, specifications, production batch numbers, etc., and then hoisted into the warehouse by cranes.

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