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The process technology of thermal expansion seamless tube.
May 03, 2018

The expanding diameter is a kind of pressure processing technology which USES hydraulic or mechanical means to expand the steel tube along the radial direction. The mechanical method is simpler and more efficient than the hydraulic method, and in the world's most advanced big gulp straight seam welding control line expansion process is adopted, its process is:

The radial expansion of the segment of the flaps of the end of the expanding machine is used for the mechanical expansion, so as to realize the process of the plastic deformation of the whole tube by step in the direction of length. There are five stages

1. Preliminary round phase. The fan block is open until all the sectors are exposed to the inner wall of the steel tube. At this time, the radius of each point in the tube inside the steel tube is nearly the same, and the steel pipe gets the initial full circle.

2. Nominal bore stage. The segment starts at the front end to reduce the movement speed until it reaches the required position, which is the circular position of the finished tube in the quality requirement.

3. Rebound compensation stage. The fan-shaped block begins to move further down the 2 stage until it reaches the required position, which is the circular position of the steel tube inside the steel tube required by the process design.

4. Stage of pressure stabilization. The circular position of the fan-shaped block in the inner circle of the steel tube remains stationary for a period of time. This is the stage of pressure stabilization required by the equipment and the expansion process.

5. Unloading return phase. The fan-shaped block begins to shrink rapidly from the inside circumference of the steel tube until it reaches the position of the initial expansion, which is the minimum contraction diameter of the fan-shaped block required by the expansion process.

In practical application, process simplification, 2 and 3 steps can be simplified, which has no effect on the diameter of the steel tube.

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