JPH06328148A - Manufacture of welded tube - Google Patents

Abstract

PURPOSE:To manufacture a welded tube with an excellent appearance quality and weld quality. CONSTITUTION:In the manufacture of a welded tube by the cage roll forming system, the tube is manufactured by tilting the direction of the rotating axis CRa of a cage roll CR in the counterclockwise direction or the clockwise direction where a slipage in the vertical direction generating when a material passes through on the contact surface of the cage roll is reduced on a surface formed with the rotating axis CRa of the cage roll CR and a line direction L.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a welded pipe by a cage roll forming system.

[0002]

2. Description of the Related Art Conventionally, in a welded pipe manufacturing line,
A forming device according to a cage roll forming method as shown in FIGS. 4 and 5 is used. This apparatus includes a plurality of inner rolls 101 whose roll widths are gradually reduced from upstream to downstream.
... is arranged, and the cage rolls 102 are arranged on both sides thereof,
102 are arranged at heights and widthwise positions that match the molding conditions, and the rolls apply a force from inside and outside to the fed strip to make the strip into a U-shape, and , Gradually bend it into a circle.

By the way, the conventional cage rolls 102 ...
As shown in FIGS. 6 to 8, the rolls 102 have convex roll surfaces (FIG. 6) (example: JP-A-59-202122) and flat surfaces (FIG. 7) (example: JP-A-59-202122). (Sho 60-174216 publication)
And those having a concave curved surface (FIG. 8) (for example, Japanese Patent Laid-Open No. 3-174922), both of which can be used for various pipe manufacturing sizes. Reference numeral 1 is a blank tube during the molding process.

[0004]

However, the cage roll 1
02 ..., 102 ..., JP-A-59-202122 and JP-A-
If the roll curved surface is convex or flat as in JP-A 60-174216, the roll contact part of the molded pipe is flattened in a streak shape and the roundness of the pipe deteriorates, resulting in poor shape quality. . When a roll having a concave curved surface is used as in JP-A-3-174922, the flatness of the pipe is improved and the roundness is improved, but the seizure phenomenon of the roll occurs like stainless steel. If the surface quality of the pipe product is required to be as mirror-like as the easy steel grade, the roll mark is transferred to the surface of the pipe, and it is difficult to secure the required quality. Roll lubrication with soluble oil etc. suppresses the seizure of the roll and eliminates the transfer of roll marks, which solves the problem of appearance quality.However, roll lubrication of difficult-to-weld materials such as stainless steel is unfavorable for welding quality. ,
It is visible that the welding becomes unstable and the strength of the weld deteriorates due to the influence of the lubricant.

The present invention eliminates the conventional defects, and an object thereof is to ensure excellent appearance quality and welding quality.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a method for manufacturing a welded pipe by a cage roll forming method, in which the direction of the rotation axis of the cage roll is set on the plane formed by the rotation axis of the cage roll and the line direction. The pipe is made by inclining it counterclockwise or clockwise so that the vertical slippage that occurs when the material passes through the cage roll contact surface is reduced.

[0007]

FIG. 10 shows an example of the transition of the height of an arbitrary point in the circumferential direction of the raw tube 1 during the forming process by the cage roll forming method, for example, an arbitrary point defined on the edge portion 1A and the side portion 1B. FIG. In FIG. 10, the height of the bottom line 1C of the pipe is constant. From FIG. 10, the height of any point in the circumferential direction of the raw pipe 1 in the cage roll forming zone tends to increase from the upstream to the midstream, reach a peak in the midstream, and decrease in the downstream. In contrast,
The direction of the rotation axis CRa of the conventional cage roll CR is shown in FIG.
Since the cage roll CR is set at a right angle to the line direction L as shown in (3), the rotation direction R of the cage roll CR at the contact portion with the material always faces the line direction L and is different from the traveling direction M of the material at the contact portion. Therefore, when the material comes into contact with and passes through the individual cage rolls CR, the material slides vertically on the roll surface, and a vertical frictional force is generated between the cage rolls CR and the material. When a steel type such as stainless steel, which easily causes a seizure of rolls, is pipe-formed without lubrication, the frictional force between the cage roll CR and the material in the vertical direction becomes large, which causes roll marks.

In the present invention, the direction of the rotation axis CRa of the cage roll CR is set to the rotation axis CR of the cage roll CR.
By inclining in a counterclockwise direction (FIG. 1) or a clockwise direction (FIG. 2) on the plane formed by a and the line direction L, FIG.
Further, as shown in FIG. 2, the advancing direction of the material at the roll contact portion and the rotating direction of the roll can be made substantially coincident with each other. As a result, the vertical frictional force generated between the cage roll and the material is extremely small, and no roll mark is produced even when stainless steel or the like is pipe-formed without lubrication. FIG. 11 shows the relationship between the amount of deviation between the advancing angle of the material of the roll contact portion and the angle of the roll rotation direction with respect to the line direction, and the frequency of roll mark occurrence. As shown in FIG. 11, since roll marks are generated when the shift amount exceeds 5.0 °, the direction of the rotation axis CRa of the cage roll CR is set so that the shift angle becomes 5.0 ° or less. Rotation axis C
It is desirable to incline counterclockwise or clockwise on the plane formed by Ra and the line direction.

[0009]

EXAMPLE FIG. 3 shows a welded pipe manufacturing apparatus in an example of the present invention. From the upstream side to the downstream side, the edge bend roll EB, the first center bend roll 1CB, the second to fourth center bend rolls 2CB, 3CB, 4CB and a large number of cage rolls CR arranged on both sides of these rolls CR, ..., C
R ..., First and second fin pass rolls 1F, 2F, rotary seam guide roll RSG, high frequency welding machine HFW
And the squeeze roll SQ are sequentially arranged.

Among these rolls, the edge bend roll EB, the first center bend roll 1CB, and the second to fourth rolls.
The center bend rolls 2CB, 3CB, 4CB, the first and second fin pass rolls 1F, 2F, and the rotary seam guide roll RSG are composed of upper rolls and lower rolls, and have a plurality of cage rolls CR ..., CR ..., Squeeze roll SQ. Has a left roll and a right roll.

The edge pipe roll EB is used to bend the edge portion of the raw pipe of the strip, the first center bend roll 1CB is used to slightly bend the side portion of the raw pipe, and the second to fourth center bend rolls 2CB and 3CB are used. 4CB restrains the boundary part between the side part of the strip and the bottom part of the strip to the bottom part of the strip, and the cage rolls CR, CR ... apply lateral pressure from both sides to the edge part to the side part of the strip. By adding it, the tube 1 having an oval cross section is formed.

Next, the first and second fin pass rolls 1
In F and 2F, the raw pipe is pressed and formed, the side portion of the raw pipe is overhanged, and the edge portion of the raw pipe and each of the above boundary portions are bent and bent back to be close to a circular shape, and the rotary seam guide roll RSG Then, the welding position of the raw pipe is adjusted, a welding current is applied to the joint by the high-frequency welding machine HFW to heat and melt the joint, and the joint is upset joined by the squeeze roll SQ.

By the way, the cage rolls CR ...
Individual rolls are arranged on both sides, and each roll CR has a separate rotation axis CRa.
Is the rotation axis CRa of the roll CR and the line direction L.
It has a structure in which the tilt can be adjusted counterclockwise or clockwise on the plane formed by and. Material advancing direction M and roll rotating direction R at the roll contact portion of the outer diameter of the pipe to be manufactured
And the inclination of the roll is adjusted so that the vertical slippage that occurs when the material passes through the cage roll contact surface is reduced. The cage roll CR is additionally provided with roll advancing / retracting adjusting means and ascending / descending adjusting means as means for also having an outer diameter size.

With the above apparatus, a pipe having an outer diameter of 22.22 to 60.5 mm was manufactured using a stainless steel strip having a plate thickness of 0.8 to 3.0 mm without roll lubrication, but cage rolls CR ..., CR ...
No roll mark was found to be generated.

[0015]

As described above, according to the present invention, by tilting the direction of the rotation axis of the cage roll in the counterclockwise or clockwise direction on the plane formed by the rotation axis of the roll and the line direction, the cage is rotated. The frictional force in the vertical direction at the contact portion between the roll and the material can be made extremely small, a roll mark is not generated on the surface of the welded pipe, the appearance can be made beautiful, and the quality can be improved.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state in which a cage roll is tilted counterclockwise in the method of the present invention.

FIG. 2 is a schematic view showing a state in which a cage roll is tilted clockwise in the method of the present invention.

FIG. 3 is a schematic view showing an example of a welded pipe manufacturing apparatus used for carrying out the present invention.

FIG. 4 is a plan view showing a conventional welded pipe manufacturing apparatus.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a schematic view showing a molding state by a cage roll provided with a roll surface having a convex curved surface.

FIG. 7 is a schematic view showing a molding state by a cage roll having a flat roll surface.

FIG. 8 is a schematic view showing a molding state by a cage roll having a concave curved roll surface.

FIG. 9 is a schematic diagram showing a setting state of a cage roll according to a conventional method.

FIG. 10 is a diagram showing an example of the transition of the height of an arbitrary point in the circumferential direction of the raw pipe during the forming process.

FIG. 11 is a frequency chart showing the relationship between the amount of deviation between the advancing angle of the material of the roll contact portion and the angle in the direction of roll rotation with respect to the line direction, and the frequency of roll mark generation.

[Explanation of symbols]

 CR cage roll CRa rotating shaft

Claims (1)

[Claims] 1. A method for manufacturing a welded pipe by a cage roll forming method, wherein a material passes through a cage roll contact surface in a direction defined by the rotation axis of the cage roll and the line direction in the direction of the rotation axis of the cage roll. A method for manufacturing a welded pipe, which comprises inclining in a counterclockwise direction or a clockwise direction to reduce slippage in a vertical direction that occurs when the pipe is manufactured.