CN104874616A

CN104874616A - Wall thickness precision control method of hot rolled seamless steel pipes and roll pass

Info

Publication number: CN104874616A
Application number: CN201410068310.7A
Authority: CN
Inventors: 唐华平; 姜永正
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2014-02-28
Filing date: 2014-02-28
Publication date: 2015-09-02
Anticipated expiration: 2034-02-28
Also published as: CN104874616B

Abstract

The invention relates to the field of seamless steel pipe production, and particularly to a wall thickness precision control method of hot rolled seamless steel pipes and roll pass. The invention aims to solve the technical issue that the wall thickness is nonuniform in the transversal direction during a seamless steel pipe rolling process. Novel rolling pass is designed to make the steel pipes be under the affect of rolling torques encircling axes of the steel pipes besides the roll force during a rolling process, the steel pipes can pivot the axes of the steel pipes because the steel pipes is under the affect of the rolling torques during the rolling process, so that the wall thickness precision in the transversal direction of the seamless steel pipes can be controlled. By adopting the wall thickness precision control method of the hot rolled seamless steel pipes and the roll pass, the defect of nonuniform transverse wall thickness of seamless steel pipes can be overcome during a rolling process, the quality and the rolling yield of the seamless steel pipes can be raised.

Description

A kind of control method of hot rolled seamless steel tube wall thickness accuracy and roll pass

Technical field

The invention belongs to seamless steel tube production field, be specifically related to the control method of wall thickness accuracy and corresponding roll pass.

Background technology

The process that hot rolled seamless steel tube is produced is: initial circular solid blanks is bored a hole through high temperature, become hollow hollow billet, hollow billet is after Semi-floating MPM, become the hollow hollow forging with certain size, hollow forging, by the rolling of size-reducing mill group, becomes the seamless steel pipe meeting dimensional requirement (being generally external diameter and wall thickness).Among these three deformation techniques, because working condition cannot reach perfect condition, fished pipe usually can be caused to there is the phenomenon of transverse wall thickness ununiformity.The transverse wall thickness ununiformity problem of steel pipe causes mass-produced steel pipe to meet instructions for use, is a kind of serious wasting of resources.The order of severity of transverse wall thickness ununiformity is by the ratios affect of external diameter (D) with wall thickness (T), the ratio of D/T is less, wall unevenness phenomenon is more serious, particularly the transverse wall thickness ununiformity problem of small-diameter thick-walled seamless steel pipe is especially serious, if steel pipe cross section internal via shape is interior six sides, triangle and heart etc.

Summary of the invention

In order to overcome the problems referred to above, the object of the present invention is to provide a kind of method that can alleviate the transverse wall thickness ununiformity problem occurred in roll seamless steel tube process, improve wall thickness of seamless steel tube precision, solve the serious uneven problem of small-diameter thick-walled wall thickness of seamless steel tube, improve the resource utilization of product.

Technical scheme of the present invention is: by designing a kind of new roll pass, make steel pipe in the operation of rolling except the effect being subject to roll-force, also be subject to the effect of the roll torque around own axes, thus make steel pipe in the operation of rolling owing to being subject to while roll-force effect deforms, being rotated around own axes.

The invention has the beneficial effects as follows:

1, adopt the present invention, steel pipe constantly rotates around axis in the operation of rolling, and the contact position of steel tube surface and roll constantly changes, and reached unanimity with extraneous exchange heat in each position of steel tube surface, the Temperature Distribution of steel tube surface improves.

2, the present invention is adopted, steel pipe constantly rotates around axis in the operation of rolling, steel tube surface each position from big to small stressed, constantly changing from small to large, stress distribution, the Strain Distribution of steel tube surface also constantly change, from the whole operation of rolling, the stress and strain distribution of steel pipe obtains homogenising.

3, by the continuous rotation of steel pipe around own axes, the lateral flow of steel duct metal is more active, and metal is strengthened by the flowing of heavy wall to thin-walled place, and existing wall unevenness is alleviated.

4, the present invention only needs the bamboo product stage to adopt new section design method, using newly-designed roll, need not quote other equipment when producing, simple.

Accompanying drawing explanation

Fig. 1 is roll pass schematic diagram.

Fig. 2 is steel pipe rotary schematic diagram.

Detailed description of the invention

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described.

Figure 1 shows that roll pass schematic diagram, number in the figure 1 is roll cross section, 2 is circle of steel tube profile, the pass shape of roll is continuous and derivable lines, there is eccentric distance e in centre of form O1 and the steel pipe cross section center of circle O of pass, with steel pipe center of circle O for reference origin, the characteristic size of pass consists predominantly of size a, size b and size c and angle [alpha] and β, angle [alpha] and β sum are 120 °.In Fig. 1, t represents sizing reduction, in α angular range t be on the occasion of, there is sizing reduction, there is interaction force between steel pipe and roll, in β angular range, t is negative value, both has gap between steel pipe and roll, not tube reducing in this angular range, without active force between steel pipe and roll.

Figure 2 shows that the schematic diagram that steel pipe rotates around own axes.Number in the figure 1,2,3 is respectively the roll that 3 are in 120 °, and 4 is circle of steel tube profile, and 5 is the sizing reduction between roll 1 and steel pipe, and 6 is the sizing reduction between roll 2 and steel pipe, and 7 is the sizing reduction between roll 3 and steel pipe.In the operation of rolling, steel pipe is subject to roll-force resultant radial force F1, F2 and F3 centre of form O1, O2 and O3 respectively by roll pass of roll 1, roll 2 and roll 3, namely there is eccentric throw in relative steel pipe center of circle O, namely F1, F2 O relative to F3 produces opplied moment and is respectively M1, M2 and M3, the direction of three moments is clockwise, and steel pipe rotates around self center of circle O under the effect of moment M1, M2 and M3.

Claims

1. the feature of the control method of the horizontal wall thickness accuracy of hot rolled seamless steel tube is: in the operation of rolling, steel pipe constantly rotates around own axes.

2. be according to the feature of the roll pass of claim 1 design: the pass shape of roll is continuous and derivable lines (comprising circular arc, elliptic arc), and the centre of form of roll pass and the center of circle of steel pipe exist eccentric throw.

3. be according to the feature of the roll pass of claim 1 design: in the operation of rolling, single roll exists rotating torque to the axis of steel pipe with joint efforts to the rolling that steel pipe applies.