How is the solid tube blank pierced into hollow tube in the process of cross rolling perforation of welded steel pipe?

At the beginning, the welded steel pipe blank is fed into the roll by the pusher and bitten by the roll. The roll drives the welded steel pipe blank to rotate and move forward at the same time. The welded steel pipe blank can only contact with the roll and does not contact the guide plate during one bite. The welded steel pipe billet enters zone I after being bitten by the roll. Due to the taper on the working surface of the roll inlet cone, the welded steel pipe billet moving forward gradually along the piercing direction is compressed in diameter. The welded steel pipe blank continues to move forward, and after meeting the top head, the nose of the top head is inserted into the centering hole on the front face of the welded steel pipe blank, then it enters zone II.

How is the solid tube blank pierced into hollow tube in the process of cross rolling perforation of welded steel pipe?

At this time, the welded steel pipe blank is reduced under the action of the roll and the head, and the guide plate plays the role of controlling the transverse deformation. The final shape of the tube wall is at the point where the top conical section and the straight section contact. After reaching the top conical section, the tube wall flattens because the busbar of the top conical section is parallel to the cone busbar of the roll outlet. Because the interface of the capillary is elliptical and the section of the tip is circular, there is a gap between the tip and the hole in the capillary tube. Because of the gap, the capillary can be free from the opening tip. When the inner wall of the capillary completely leaves the apex, it enters the third region of the deformation zone, that is, the circular region of the capillary. At this time, the tube can only contact the roll. Because there is a taper on the roll exit cone, the distance between the rolls is gradually increased, and the compression amount on the diameter of the tube in zone III is gradually reduced, and the compression amount is zero at the point where the tube leaves the roll, and the original oval section of the tube will become a circular section.

What is the motion speed of the rolled piece when it is crossed?

It is a velocity vector analysis diagram of any point in the deformation zone under normal rolling conditions. The point around which the roll rotates when the feed Angle is adjusted is the center of rotation O, the vertical line of the center to the rolling line is the rotation axis, the plane composed of the rotation axis and the rolling line is the rolling main plane, the plane composed of the roll axis is the rolling main plane, and the plane including the rolling line is the vertical plane. The axial and tangential components of roll surface rotation velocity at any point O2 in the deformation zone can be obtained.

There is plastic deformation of the metal in the deformation zone, and it is impossible to travel at the same speed with the corresponding contact point, and there is a certain relative slide between each other, which is generally expressed by the ratio of the metal's motion speed to the corresponding contact point of the roller surface, called the sliding coefficient. The axial and tangential speed of the metal in the rolled piece.

Because the dimensions of the exit section of the deformation zone are known and the sliding coefficient is easy to measure, the parameters of the exit section are often used to express the above relations. If the torsion deformation of the rolled parts in the deformation zone is ignored, the principle of the metal second flow in the direction of the rolling axis is equal.

In the process of diagonal rolling, because the welded steel pipe billet is driven by the roll, the roll will pass the corresponding speed to the metal, but because the metal in the deformation zone has plastic deformation, it is impossible to run at the same speed with the corresponding contact point, there is a certain relative sliding between each other, which is generally expressed by the metal movement speed and the corresponding contact point of the roller surface, called the sliding coefficient. The sliding coefficient is divided into tangential sliding coefficient and axial sliding coefficient.