JPH04231116A - Manufacture of electro-resistance-welded tube - Google Patents

Abstract

PURPOSE:To prevent a forming stock from rolling without impairing its formability. CONSTITUTION:In the manufacture of an electro-resistance-welded tube, a rolling amount of detecting device to detect the rolling amount of the formed stock is provided at a forming area on the upstream side of a fin pass area and both upper and lower roll axes of pinch rolls installed on the inlet side of a forming stand are crossed by an intersection angle corresponding to a rolling amount detected by a rolling amount detecting device to the axial line crossed orthogonally to the forming line for forming to prevent the formed stock from rolling.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electric resistance welded tube, and more particularly to a method of manufacturing an electric resistance welded tube suitable for preventing rolling of a molded material.

0002

2. Description of the Related Art Generally, as shown in FIG. 1, the forming of an electric resistance welded tube consists of a breakdown region, a cluster region, a fin pass region, and a squeeze region in order from upstream. Molding is performed by restraining the molded material with upper and lower rolls in the breakdown region, with side rolls in the cluster region, and by restraining the entire tubular molded material with rolls and fins in the fin pass region.

[0003] At this time, since there is no restraint in the width direction for the molded material in the breakdown region and cluster region of the upstream molding region, rolling of the molded material occurs due to causes such as bending of the strip, poor centering, or poor equipment accuracy. Easy to do. In particular, rolling occurs easily with materials with a large t/D (t: plate thickness, D: pipe diameter), and when entering the fin pass roll, the end face of the tubular material becomes uneven on the left and right sides, and during welding. It has a negative effect on the butt shape. In addition, if the rolling is large, molding defects and roll flaws occur, making stable molding impossible and leading to the stoppage of the production line. As described above, the occurrence of rolling results in a significant decrease in quality and productivity.

Conventionally, as a countermeasure against rolling, there is a method of providing a centering device on the entrance side of the molding machine, as disclosed in JP-A-60-133928, but shifting the center of the strip on the entrance side is difficult for forming The bending of the edges, which is an important point, is not done symmetrically, which has a negative effect on subsequent forming. Furthermore, JP-A-60-133
As disclosed in No. 929, there is a method of changing the left and right gaps between upper and lower forming rolls, but in such a method, the contact surface pressure of the roll on the side where the rolling reduction is stronger increases, causing flaws in the forming material.

[0005] There is also a method of applying rotational moment to a molded material using movable forming rolls in an intermediate forming area as disclosed in JP-A-62-33016, or as disclosed in JP-A-63-194821. There is a method of moving one side roll up and down, but all of these methods mean that the forming roll is offset from the center, which adversely affects the quality of the formed material due to forming defects and roll flaws. It is clear that

[0006]

[Problems to be Solved by the Invention] As mentioned above, although the conventional rolling prevention technology or correction technology can prevent or correct the rolling of molded materials, they have drawbacks that impair the moldability of the molded material. When evaluated, it could not be said to be a sufficient measure.

An object of the present invention is to prevent rolling of a molded material without impairing its moldability.

[0008]

[Means for Solving the Problems] The present invention provides a method for manufacturing an electric resistance welded pipe, in which a rolling amount detection device for detecting the amount of rolling of a forming material is provided in a forming region upstream of a fin pass region, and the rolling amount detection device Forming is performed by making the roll axes of both the upper and lower rolls of the pinch roll installed on the entry side of the forming stand intersect with the axis perpendicular to the forming line at an intersecting angle corresponding to the detected rolling amount, and forming the material. This is to prevent rolling.

[0009]

[Operation] When the roll axes of the upper and lower rolls of the pinch roll are perpendicular to the forming direction, the only horizontal force that acts on the forming material is the driving force of the rolls in the forming direction. On the other hand, when the roll axis is made to intersect diagonally with respect to the axis perpendicular to the forming direction, the driving force of the roll is applied obliquely to the forming direction, resulting in a component of force perpendicular to the forming direction. The force acts as a corrective force that prevents rolling of the molded material. Therefore, if an appropriate crossing angle is given to the rolling amount, the rolling can be made zero. According to this method, there is no offset of the forming rolls, and the forming roll gaps are even on the left and right sides, so that there is no loss of formability such as forming defects or roll flaws.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall view of a forming line for electric resistance welded pipes. The steel strip 1 is fed into a forming stand by pinch rolls 100, sequentially formed by breakdown rolls 2 to 6, cluster rolls 7 to 11, fin pass rolls 12 to 15, and welded by squeeze rolls 16. A rolling amount detection device 17 is installed at an appropriate position in the intermediate zone between the flake down region and the fin pass region. Here, the detection device 17 may be either a mechanical device such as a contact roller or an optical device such as an image sensor.

As shown in FIG. 2, the amount of rolling is determined by the difference Δh between the heights of the left and right edges of the molded material 1.
7, this is measured and fed back, and the roll axis 5C of the upper roll 5A of the pinch roll 100 and the roll axis 5D of the lower roll 5B are orthogonal to the forming line as shown in FIG. 3 according to the rolling amount. Rolling of the molded material 1 is prevented by performing the molding crossing the axis A.

This rolling prevention principle is based on the fact that when the roll axis is perpendicular to the forming direction, as shown in FIG.
However, by crossing the upper roll 5A and the lower roll 5B, the driving force 18 by the upper roll 5A and lower roll 5B is applied diagonally to the forming direction, as shown in FIG. A force 19 is generated, which acts as a corrective force to prevent rolling of the molded material 1.

The relationship between the rolling amount Δh and the crossing angle α between the roll axis and the axis perpendicular to the forming line, which is necessary to correct this, is investigated and the results are shown in FIG. As can be seen from this figure, if an appropriate crossing angle α is given to a certain amount of rolling Δh, the rolling can be reduced to 0.

[0014] When the roll axes intersect, the center in the width direction of the rolls is used as the crossing point, but the same effect can be obtained by setting the ends in the width direction of the rolls as the crossing point.

[0015] According to this method, there is no offset of the forming rolls, and the forming roll gaps are even on both sides, so there is no risk of roll flaws occurring.

Furthermore, from the viewpoint of keeping the roll gap constant, it is desirable that the upper and lower rolls 5A and 5B have the same intersecting angle.

As is clear from the above description, according to the present invention, rolling can be prevented using a simple principle without impairing the formability of the material, and the effect is remarkable.

[0018]

[Effects of the Invention] In the production of electric resistance welded pipes, the present invention can correct and prevent rolling of the molded material during molding online without impairing formability, and has a great effect on improving productivity and quality. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a forming line for an electric resistance welded tube.

FIG. 2 is a diagram showing rolling detection.

FIG. 3 is a diagram showing a state in which the upper and lower roll axes of the pinch rolls intersect with the axis perpendicular to the forming line.

FIG. 4 is a schematic diagram showing the horizontal force exerted on the molded material when the roll shaft is disposed perpendicular to the molding line.

FIG. 5 is a schematic diagram showing the horizontal force applied to the molded material when the roll axis intersects the axis perpendicular to the molding line.

FIG. 6 is a diagram showing the relationship between the amount of rolling and the crossing angle of the roll axes for correcting this.

[Explanation of symbols]

1 Molding materials 2 to 6 Breakdown roll 5A Upper roll 5B Lower roll 5C Roll axis 5D Lower roll A Axis lines 12 to 15 perpendicular to the molding line Fin pass roll 17 Rolling amount detection device 18 Driving force acting on the molding material 19 On the molding material Component 1 of the driving force perpendicular to the forming direction
00 pinch roll

Claims (1)

[Claims] Claim 1: In a method for manufacturing an electric resistance welded pipe, a rolling amount detection device for detecting the amount of rolling of a molded material is provided in a forming area upstream of a fin pass area, and a rolling amount detecting device is provided in a forming area upstream of a fin pass area, and a rolling amount detecting device is provided in a forming area upstream of a fin pass area. Forming is performed by making the roll axes of both the upper and lower rolls of the pinch roll installed on the entry side of the forming stand intersect with the axis perpendicular to the forming line at an intersecting angle, thereby preventing rolling of the forming material. A method of manufacturing an ERW pipe.