Asymmetric roller for sizing and reducing machine

Abstract

The invention belongs to the technical field of hot-rolled seamless steel pipes, and particularly relates to an asymmetric roller for a sizing and reducing machine. The asymmetric roller comprises oval rollers, and is characterized in that the oval hole type center lines of the oval rollers do not coincide with the center axis of the roller, and the oval hole type center lines of all the oval rollers deviate towards one side of the center axis of the roller by the distance E1. According to the asymmetric roller, on the premise that an original longitudinal rolling sizing and reducing unit is not changed, the traditional symmetric roller hole type design is changed, and through the bilateral asymmetry on the hole type design, a steel pipe bears a couple function in the sizing and reducing process; and the couples applied by all the rollers to the steel pipe are all in the clockwise direction or all in the anticlockwise direction, the steel pipe slightly rotates in the sizing and reducing process, the thickened segments of racks are staggered, the effect that the thickened segments of the racks are stacked in the same area is avoided, the inner square phenomenon of the steel pipe iseliminated, and the wall thickness precision of the steel pipe is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of hot-rolled seamless steel pipes, and in particular relates to an asymmetric roll used for a sizing and reducing machine. Background technique [0002] The steel pipe sizing, reducing and tension reducing process is a continuous rolling process with a hollow body without a mandrel. There are many forms of steel pipe sizing and reducing machines, which can be divided into two-roll, three-roll and four-roll types according to the number of rolls. During the rolling process of the longitudinal rolling sizing and reducing machine, if the pipe has a large diameter reduction and thick-walled pipe, the inner wall of the steel pipe will form inner squares or inner hexagonal inner polygonal defects, which reduces the wall thickness accuracy of the steel pipe. Take the three-roll sizing and reducing machine as an example, such as figure 1 The elliptical pass pattern of the traditional three-roller sizing and reduci...

AI Technical Summary

Problems solved by technology

For thin-walled pipes, the additional influence of the additional axial stress on the change of wall thickness is small, and the phenomenon of "inner hexagonal" is not obvious, but for thick-walled pipes, the additional influence of additional axial stress on the change of wall thickness is greater, and the phenomenon of "inner hexagonal" is not obvious. "The phenomenon is more obvious, resulting in a decrease in wall thickness accuracy. The current pass design method can only reduce the inner tendency of thick-walled pipes, but cannot completely eliminate them.

[0003] The deflection angle θ of each roller axis of the cross rolling sizing and reducing machine forms cross rolling, so that the steel pipe has a slight rotation when it advances. Defects, but the cross rolling sizing and reducing machine has a complex structure and is not easy to manufacture; the deflection angle θ is different for each frame, which is difficult to control; the process requires only a small rotation of the steel pipe between the two frames, and it is difficult to determine the deflection angle θ; cross rolling increases the distance between the racks , the thickening section increases when the tension is reduced; based on the above reasons, although the fixed diameter reduction of cross rolling can eliminate the inner square, it is difficult to apply

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