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Hot rolled thick-walled seamless steel tube centering
2021-11-18 10:47:45

Why is it necessary to center the tube blank when hot rolling thick wall seamless steel tube? What's the significance. In order to know why the tube blank must be centered when hot rolling thick wall seamless steel tube, what is the centering of tube blank first? In the production of hot-rolled seamless steel tube, in order to correctly align the nose of the plug with the front end of the tube blank during piercing, a shallow round hole is machined at the front end of the tube blank before the tube blank is pierced. This process is called centering.

So why must the billet be centered when hot rolling thick wall seamless steel tube? The purpose of tube blank centering is to help the nose of the plug align with the axis of tube blank during piercing, to prevent the deviation during piercing, to reduce the uneven wall thickness of the front end of the tube, and to improve the secondary biting conditions for oblique piercing, so that the piercing process can be carried out smoothly.

By centering the front end of the tube blank, the concave of the deformed front end is increased, which is beneficial to aligning the nose of the head and reducing the uneven wall thickness of the front carbonyl. In particular, centering is more important when piercing thick walled tubes. Because of the small amount of compression of thick walled tubes, the concave of the front end after deformation is also small. At the same time, the diameter of the plug is much smaller than that of the tube blank (compared with the thin-walled tube). All these increase the probability of misalignment when the nose of the top and the front end of the tube blank meet. Therefore, in order to reduce the uneven wall thickness and metal consumption, it is important to center when rolling thick wall pipe.

The second bite condition can also be improved by centering, because the compression before the head is increased.

When some alloy steel is pierced, a small amount of compression is often used to achieve normal second bite and prevent uneven wall thickness at the front end. At this time, centering is particularly important. If it is not centered, the distance between the tube blank and the nose of the head is small, that is to say, the contact area is small. When the friction force of the roll drawn into the tube blank cloth is less than the resistance of the head, the second bite cannot be achieved That is to say, through centering, the contact area can be increased, so as to increase the traction friction, which is conducive to the realization of secondary bite. But centring is not necessary in any case. For example, when rolling small-diameter thin-walled tube, centring or not has little influence on the front wall thickness unevenness, and the tube blank can be pierced directly without centring.