JPH11277110A - Manufacture of square pipe, and forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture various kinds of square pipes with the same forming rolls by canceling rotational force in the circumferential direction which is the cause of twist which is liable to generate on pipe stocks by the inclination of forming rolls. SOLUTION: In this device, at least in one forming stand of the plural forming rolls which are arranged in multistage, mounting plates 10 on which the roll chock forming rolls 21a -21d for supporting the forming rolls 20a -20d provided with the caliber are fixed are rotatably arranged. The pipe stock is formed into a intermediate shape in the entire area or a part in the width direction of the peripheral surface of the forming rolls 20a -20d and, at the time of forming the intermediate pipe into the square pipe of the target size in the forming stand of the final stage, the forming rolls 20a -20d are inclined at a inclined angle by which the rotational force around the axis of the pipe which acts on the pipe stock during forming is canceled by adjusting the rotational amount of the mounting plates 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for reducing the twist around a pipe axis when producing square pipes of various sizes using the same forming roll.

[0002]

2. Description of the Related Art When a square tube is roll-formed from a cylindrical tube, a total of 4 squares are formed in the left, right, up and down directions facing the peripheral surface of the tube.
A single-stage or multiple-stage forming stand in which a plurality of roll sets are arranged is used. In a normal forming stand, since the positional relationship of the forming roll with respect to the base tube is fixed, only a square tube having one type of size is manufactured. However, it is desired to provide square tubes having various sizes according to the application, and when manufacturing square tubes having different sizes, complicated and troublesome operations such as changing rolls are required. In this regard, as introduced in JP-A-6-170412, when the positional relationship of the forming roll with respect to the raw tube is made variable, square tubes having various sizes can be formed by one forming stand. In this method, the center axis of rotation of the forming roll is set so as to pass through a center point of curvature of the roll caliber or a point separated from the center point of curvature by a predetermined distance in the roll axis direction.

[0003]

Problems to be Solved by the Invention
In the case of manufacturing a square tube having the maximum size with the forming stand described in Japanese Patent Publication No. 2, the raw tube comes into contact with the entire surface of the forming roll caliber in the width direction. Under this condition, the base tube contacts the roll peripheral surface symmetrically with respect to the center line in the width direction of the forming roll. But,
When manufacturing a small square tube, since the raw tube sequentially contacts the roll peripheral surface from the maximum diameter side of the forming roll, an asymmetric contact state is established with respect to the center line in the width direction of the forming roll. As a result, a circumferential rotational force from the minimum diameter side to the maximum diameter side of the forming roll as viewed from the axial direction of the raw tube or square tube is applied to the raw tube or square tube. The circumferential rotational force is later released from the last forming roll. Therefore, the square tube that has passed through the final forming stand is twisted around the tube axis due to elastic recovery in the circumferential direction. Therefore, it is necessary to remove torsion in order to make a roll-formed square tube into a product.However, it is impossible to remove torsion, which is a very slight deformation in terms of the ratio to the length in the tube axis direction, by plastic deformation of the material. Not easy.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem. The present invention has been made by making some of the molding stands themselves rotatable and adjusting the rotation angle of the molding stands. It is an object of the present invention to manufacture a square tube having a good shape by canceling out a circumferential rotational force which tends to be generated in a raw tube by twisting a forming roll. In order to achieve the object, the square tube manufacturing method of the present invention arranges a plurality of forming stands in multiple stages, and forms an elementary tube in an intermediate shape in the whole or a part of the circumferential surface width direction of a forming roll with a caliber, When forming into a square tube of the target size with the final-stage forming stand, the forming roll of the entrance-side forming stand or the exit-side forming stand is inclined at an inclination angle that negates the rotational force around the tube axis acting on the raw tube being formed. It is characterized by the following. Further, the square tube manufacturing apparatus includes an inlet-side forming stand incorporating a forming roll provided with a caliber for forming the raw tube into an intermediate shape in the entire area or a part of the circumferential surface width direction, and an intermediate-shaped raw tube having a target size. An outlet forming stand in which a flat forming roll for forming a square tube is incorporated is arranged in multiple stages, and a roll chock that supports the forming roll in at least one forming stand is attached to a rotatable mounting plate.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A molding apparatus according to the present invention has a plurality of molding stands 1 and 2 arranged in series as shown in FIG. In FIG. 1, the molding stands are arranged in two stages, but may be arranged in three or more stages as necessary. The cylindrical raw tube 3 to be molded is held by a chuck 6 provided in a hydraulic cylinder 5 of a pushing device 4 and pushed into the first molding stand 1. The raw tube 3 is formed into an intermediate shape by the first forming stand 1 and then formed into a square tube 7 having a target shape by the second forming stand 2. Of the molding stands arranged in multiple stages in this way, at least one or more molding stands from the entry side with respect to the final molding stand 2 are turned into rotary molds. Or, conversely, the molding stand on the entry side may be a fixed type and the molding stand on the final side may be a rotary type. Hereinafter, a case where the first molding stand 1 is a rotary mold will be described.

[0006] As shown in FIG.
It has a plurality of mounting plates 10 and 10, and forming rolls 20 _{a to} 20 _d are arranged between the mounting plates 10 and 10. The mounting plates 10 and 10 are provided on a bed 4
The rollers are rotatably supported by rollers 11, 11,.... As shown in the bottom view of FIG.
2 and a large-diameter portion 13, and the outer peripheral surface of the mounting plate 10 is placed on the small-diameter portion 12. A scale 14 (FIG. 4) for adjusting the rotation angle is provided at an appropriate place on the mounting plate 10.
Is attached. Also, the mounting plates 10, 10
Is a rail 1 extending in a direction perpendicular to the plane of FIG.
It is possible to move along 5,15. In the vicinity of the periphery of the mounting plates 10, four long holes 16 long in the circumferential direction are formed at equal intervals. Bolts 17 for fixing the rotary mold stand to the adjacent mold stand are inserted into the long holes 16.

[0007] Between the mounting plates 10 and 10, the tube shaft
4 roll chocks 21 at an angle of 90 degrees to the center
_a ~ 21_d Are bolted to the mounting plates 10 and 10.
Have been. Roll chock 21_a ~ 21_d Is shown in FIG.
Roll shaft 22 _a ~ 22_d Through the molding b
Rule 20_a ~ 20_d Is rotatably supported. roll
Chock 21_a ~ 21_d Has a screw shaft 23_a 
~ 23_d Is provided, and the screw shaft 23 is provided._a 
~ 23_d Roll chock 21 by the rotation of_a~ 21_d 
Forming roll 20 within_a ~ 20_d Moves linearly in the radial direction
You. Forming roll 20_a ~ 20_d The travel distance of the screw
Shaft 23_a ~ 23_d Is adjusted by the amount of rotation of
Forming space is the forming roll 20_a ~ 20_d And color 26
_a ~ 26 _d , 27_a ~ 27_d Is formed.

The forming roll 20 of the first forming stand 1_a ~
20_d Has a perimeter with a caliber and is the largest size
When manufacturing a square tube (FIG. 6),
The full width of the peripheral surface is used for molding. At this time, the pipe 3 and b
As shown in FIG.
20_a ~ 20_d Becomes symmetrical about the center line in the width direction. So
Therefore, a unidirectional rotational force is not applied to the raw tube 3 being formed.
No. On the other hand, when manufacturing square tubes smaller than the maximum size
(FIG. 7) shows each forming roll 20._a ~ 20_d The roll axis
Direction, and use a part of the roll surface for square tube forming.
You. The forming roll 20_a ~ 20_d Next door when moving
Forming roll 20 _a ~ 20_d Can interfere with each other
Notches 24 to avoid interference_a ~ 24_d Molding
Roll 20_a ~ 20_d Formed on the side.

[0009] roll in a state of using part forming the periphery, and FIG. 7 (b) in enlarged state of contact between the base pipe 3 and the roll peripheral surface, as shown by the width of the forming roll 20 _a to 20 _d It becomes asymmetric with respect to the direction center line. In this case, since the base tube 3 comes into contact with the roll peripheral surface sequentially from the maximum diameter side to the minimum diameter side of the forming rolls 20 _{a to} 20 _d , the base tube 3 or the square tube 7 is viewed from the tube axis direction. As a result, the rotational force F is applied in the circumferential direction toward the maximum diameter side. The rotational force F differs depending on the size of the square tube 7 to be manufactured, and increases as the square tube 7 having a shorter side length is formed, which causes torsion in the product square tube.

The rotational force F can be calculated from the twist generated in the square tube 7 manufactured on a trial basis. Thus, by rotating the mounting plate 10, 10 when the product angle pipe production in the opposite direction while viewing the scale 14, to offset the rotational force F by the inclination of the forming roll 20 _a to 20 _d. Forming roll 20 _a ~20 _d
Is adjusted according to the magnitude of the generated rotational force F. The blank tube 3 formed in the first stand while canceling the rotational force F is sent to the second forming stand. In the second forming station, to improve the flatness of the flat roll 25 _a to 25 parts as shown in FIG. In this way, since the twisting that occurs when producing square tubes of various sizes using the same caliber roll is suppressed, a square tube excellent in straightness can be obtained.

[0011]

EXAMPLE A square tube was manufactured using a molding apparatus in which a first stand 1 and a second stand 2 shown in FIG. 1 were arranged in series.
In each stand, forming rolls 20 _{a to} 20 _d and flat rolls 25 _{a to} 25 _d capable of forming up to 40 mm square.
It was used. Forming roll 20 _a to 20 _d is incorporated into the first forming station 1 for rotation tube axis up to 45 degrees. A stainless steel tube having a thickness of 1.0 mm and a diameter of 50.8 mm was used as the raw tube 3 to form a square tube having a side length of 40 mm. In this case, the forming roll 20 _a to 20 _d
Is used for forming the square tube, the contact state between the base tube 3 and the roll peripheral surface becomes symmetrical with respect to the center line in the roll width direction, and the rotational force F described with reference to FIG. No effect on 3. Thus, the first mold mounting plate 10, 10 of the stand 1 is set to a rotation angle of 0 °, maintaining the forming roll 20 _a to 20 _d horizontally and vertically (Figure 6).

The raw tube 3 formed by the first forming stand 1
It is fed into the second forming station 2, a horizontal and flat and maintained vertically forming roll 25 _a to 25 _d (FIG. 8)
To form a square tube 7. The obtained square tube 7 had a high degree of flatness on the sides and no twist around the tube axis. Then, a 15 mm square tube 7 was manufactured from a stainless steel tube having a thickness of 1.0 mm and a diameter of 19 mm. In this case, since about 37% in the width direction from the end of the roll peripheral surface is used for forming,
By moving the forming rolls 20 _{a to} 20 _d in the roll axis direction,
A molding space (FIG. 7) corresponding to 15 mm square was formed. In order to cancel the rotational force F generated when the contact state between the base tube 3 and the roll peripheral surface becomes asymmetric with respect to the center line in the roll width direction, the mounting plates 10 and 10 are rotated clockwise to cancel the rotational force F.
The inclination angle θ of the forming roll 20 _a to 20 _d is set to 10 degrees.

The raw tube 3 formed by the first forming stand 1
Was fed into the second forming stand 2 and formed into a square tube 7 by flat forming rolls 25 _{a to} 25 _d (FIG. 8) maintained horizontally and vertically. The obtained square tube 7 had a high degree of flatness on the sides and no twist around the tube axis as shown in FIG. 9A. For comparison, the forming rolls 20 _{a to} 20 a
Without inclining _d , a 15 mm square tube 7 was manufactured under the same conditions. In the square tube 7 obtained in this case, twist was generated around the tube axis as shown in FIG. 9B. The straightening process for correcting the twist while maintaining the rectangular cross section of the square tube 7 has been extremely difficult in practice. In the above embodiment, the first forming stand 1 is rotated to cancel the rotational force F. However, by fixing the first forming stand 1 and rotating the second forming stand 2, the rotational force F Are canceled, and the square tube 7 having a good shape is manufactured.

[0014]

As described above, according to the present invention, when a plurality of forming stands are arranged in multiple stages, and square tubes of different sizes are manufactured from the same forming roll, the rotational force applied to the raw tube by the forming rolls. The molding stand on the entry side or the exit side is rotated so as to cancel out. When formed in this state, twisting due to rotational force is suppressed, and a square tube with high straightness is manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic view of a square tube manufacturing apparatus provided with a molding stand according to the present invention.

FIG. 2 is a side view of a rotatable molding stand.

FIG. 3 is a bottom view of the molding stand.

FIG. 4 is a side view of the molding stand viewed from a pipe axis direction.

FIG. 5 is a view showing a roll arrangement in the molding stand.

FIG. 6 is a view for explaining a contact state between a forming roll and a raw tube when the entire area in the width direction of the peripheral surface is used for forming.

FIG. 7 is a diagram illustrating a contact state (a) between a forming roll and a raw tube and generation of a rotational force when a part of the circumferential surface in a width direction is used for forming.

FIG. 8 is a view for explaining a contact state between a forming roll and a raw tube in a final forming stand.

FIG. 9 is a perspective view comparing a square tube (a) manufactured by rotating the forming stand with a square tube (b) manufactured without rotating the forming stand; Figure showing

[Explanation of symbols]

1: First molding stand 2: Second molding stand
3: Raw tube 4: Pushing device 5: Hydraulic cylinder
6: Chuck 10: Mounting plate 11: Roller 12: Small diameter part 13: Large diameter part 14: Scale 15: Rail 16: Slot 1
7: bolt 20 _a to 20 _d: forming rolls 21 _a through 21 _d: chocks 22 _a through 22 _d: Roll Shaft 2
3 _a ~ 23 _d: screw shaft 24 _a to 24
_d: the notch 25 _a to 25 _d: flat roll F: rotational force acting on the blank tube when forming the small square tube theta: angle of inclination of the forming roll

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B21D 5/12 B21D 5/12 P

Claims (2)

[Claims] 1. A plurality of forming stands are arranged in multiple stages, a raw tube is formed into an intermediate shape over the whole or a part of a circumferential direction of a forming roll provided with a caliber, and a square tube having a target size is formed by a final-stage forming stand. A method of manufacturing a square tube, characterized in that when forming into a square tube, the forming rolls of the entrance-side molding stand or the exit-side molding stand are inclined at an inclination angle that counteracts the rotational force around the tube axis acting on the raw tube being molded. 2. An inlet-side forming stand incorporating a forming roll provided with a caliber for forming a tube into an intermediate shape in an entire region or a part of the circumferential surface width direction, and a tube having an intermediate shape into a square tube having a target size. An apparatus for manufacturing a square tube, comprising a plurality of output forming stands in which flat forming rolls to be formed are incorporated, and a roll chock that supports the forming rolls in at least one forming stand is mounted on a rotatable mounting plate.