JP2002361329A - Apparatus and method for bending steel tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and method for bending a steel tube capable of bending a piece of steel tube at a plurality of number of times with different bending directions when the piece of steel tube is bent at a plurality of number of times. SOLUTION: The apparatus for bending the steel tube is characterized in that the apparatus for bending the steel tube comprises a heating means to annularly heat the periphery of the steel tube, making its axial line as a center axis, a cooling means to annularly cool the annularly heated portion with the heating means, making the axial line of the steel tube as a center axis, a first tensile force imparting means to impart tensile force between force acting points at both sides by pinching the annularly heated portion set on a first eccentricity axial line of the steel tube, a transfer means to relatively transfer the steel tube, the heating means and the cooling means in the axial direction of the steel tube, a second tensile force imparting means to impart tensile force between force acting points at both sides by pinching the heating means, the cooling means and the annularly heated portion set on a second eccentricity axial line which differs from the first eccentricity axial line, and a transfer means to relatively transfer the steel tube, the heating means, and the cooling means in the axial direction of the steel tube.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe bending apparatus and method.

[0002]

2. Description of the Related Art Japanese Patent No. 2967482 by the present applicant.
No. “Steel pipe bending apparatus and method” and Japanese Patent Application No. 2000
FIG. 2 shows a conventional technique described in -51208 "Apparatus and method for bending steel pipe". Bending of a steel pipe using this device is performed in the following manner.

In FIG. 7 to FIG. 11, a steel pipe 1 is provided with a chain 4 eccentrically with respect to the central axis of the steel pipe, and is passed over the inner surface of the steel pipe 1 so that a front pressure plate 2 and a rear pressure plate 3 and a hydraulic jack 5 are provided.
Thus, a tensile force is applied to the chain 4.
The rear pressure plate 3 is integrated with the jack 5 and the steel pipe moving device 6 and moves on the rail 7 in the axial direction of the steel pipe 1.

[0004] A heating coil 10 for heating the outer periphery of the steel pipe 1 is supported by a coil holder 11.
It is connected to a heating device 12. When the heating coil is energized by the heating device 12, the steel pipe 1 is sequentially heated by the induction current from the heating coil 10.

Since the heating coil 10 is an annular heating coil, the periphery of the steel pipe 1 is annularly heated around its axis as a central axis. FIG. 12 shows an enlarged sectional view of the heating coil 10 and the steel pipe 1. The annular heating section k is guided to an annular flow path 10 a in the heating coil 10, and is sequentially cooled from the front side by cooling water 12 ejected from a large number of holes h provided in the heating coil 10 in an annular arrangement.

Since the hole h of the heating coil 10 is provided in an annular shape, the cooling portion is an annular cooling portion c having the axis of the steel pipe 1 as a central axis. The annular heating section is annularly cooled from the front side by the annular cooling section c.

As a result, an annular local heating section k having the axis as the central axis is sequentially formed in the steel pipe 1 as the steel pipe advances. That is, the local heating unit k moves (retreats) in the axial direction as the steel pipe 1 advances.

The temperature of the annular local heating section k is higher than the recrystallization temperature. In the example of the carbon steel pipe shown in FIG. 12, the temperature of the heating zone having the axial width W is 760.
C. to 900C.

In FIGS. 7 to 11, a steel pipe moving device 6 is shown.
Can be adjusted by the steel pipe moving speed adjuster 16 and the steel pipe moving speed indicator 35.

The hydraulic jack 5 can adjust a hydraulic jack pulling force or a hydraulic jack pulling speed by a hydraulic jack pulling force adjuster 14, a hydraulic jack pulling force indicator 31, and a hydraulic jack pulling speed adjuster 15. The ratio between the jack pulling speed and the relative moving speed between the local heating unit and the steel pipe is adjusted by the adjuster 17.

The heating temperature of the steel pipe 1 by the heating coil 10 and the temperature and amount of the cooling water 12 are controlled by control means (not shown).

Bending of a steel pipe using this apparatus is performed in the following manner. (1) When a tensile force is applied between the fixed points at both ends of the chain 4 by the hydraulic jack 5, since both fixed ends are on the eccentric axis of the steel pipe, the steel pipe 1 receives the compressive force in the direction of the eccentric axis. Annular local heating section t which moves sequentially (see FIG. 12)
Bends continuously at At this time, if the pulling speed of the hydraulic jack 5 is increased or the pulling force is increased, the amount of bending deformation per unit time increases, so that the bending radius can be reduced. If the speed is reduced, the bending radius can be reduced for the same reason. Conversely, if the pulling speed of the jack 5 is reduced or the tensile force is reduced, the amount of bending deformation per unit time is reduced, so that the bending radius can be increased.

[0013]

The conventional steel pipe bending apparatus has the following problems. S shown in FIGS. 1 to 6
When bending a single steel pipe several times in different bending directions, such as in a U-shaped bend, in the first bending, the optimum conditions for the following bending are simple. Can be realized.

(1) The action direction of the tensile force of the chain is
It can be kept substantially parallel to the axial direction of the steel pipe to be bent. (2) The direction of action of the tensile force of the chain can be kept substantially perpendicular to the annular heating section. (3) The acting axis of the tensile force of the chain can be made closer to the maximum axial compression side of the steel pipe to be bent.

In the following, the above (1), (2),
The property (3) is referred to as "condition for optimizing the axis of action of the chain pulling force".

However, if the second bending is performed in a bending direction different from the first bending, the "condition for optimizing the acting axis of the chain pulling force" is not satisfied, resulting in an unstable bending shape. Was.

The present invention has been made under such a technical background, and one steel pipe such as an S-shaped bend is provided.
It is an object of the present invention to provide a method for performing a stable bending process by establishing conditions for optimizing an axis of action of a tensile force of a chain when performing a plurality of tube bending processes having different bending directions.

[0018]

The steel pipe bending apparatus provided by the present invention is as follows. (1) Heating means for annularly heating the periphery of a steel pipe around its axis as a center axis, cooling means for annularly cooling an annular heating portion by the heating means around the axis of the steel pipe as a center axis, and first eccentricity of the steel pipe A first tensile force applying means for applying a tensile force between points of action of forces on both sides of the annular heating portion set on the axis, and the steel pipe, the heating means and the cooling means in the axial direction of the steel pipe; Moving means for performing relative movement to the heating means, the cooling means, and the forces on both sides of the annular heating portion set on a second eccentric axis different from the first eccentric axis. A steel pipe bending process comprising: a second tensile force applying means for applying a tensile force between action points; and a moving means for relatively moving the steel pipe, the heating means, and the cooling means in the axial direction of the steel pipe. apparatus.

The steel pipe bending method provided by the present invention is as follows. (1) An annular local heating section having a central axis around the axis of the steel pipe is formed, and the local heating section is set on the eccentric axis of the steel pipe while being relatively moved in the axial direction of the steel pipe. The first bending process is performed by applying a bending moment to the steel pipe by applying a tensile force between the points of action of the forces on both sides of the heating section, and after the first bending processing, the bending pipe is moved along its axis. Is rotated at an arbitrary angle around the central axis, and thereafter, an annular local heating section having the central axis as the central axis is formed around the steel pipe to be subjected to the second bending, and this is heated relative to the steel pipe in the axial direction of the steel pipe. While applying the bending moment to the steel pipe by applying a tensile force between the points of action of the forces on both sides of the annular local heating portion set on the eccentric axis of the steel pipe while moving, The force acting axis is set on the second eccentric axis. Steel tube bending method is characterized in that by the second tensile force application means performs the second bending.

[0020]

[Action] Even in the case of multiple bending of a single steel pipe with different bending directions, such as S-shaped bending, the axis of action of the tensile force can be optimized. it can.

[0021]

Embodiments of the present invention will be described below with reference to embodiments. Embodiment 1 FIGS. 1 and 2 show an embodiment of the first apparatus. The embodiment of the first method is realized by the steel pipe bending apparatus of this embodiment. In FIG. 1, a steel pipe 1 is provided with a chain 4 eccentrically with respect to a central axis of the steel pipe, and is passed through an inner surface thereof, and a front compression plate 2 and a rear compression plate 3 and a hydraulic jack 5 are provided.
Thus, a tensile force is applied to the chain 4.
A spacer 18 for adjusting the axis of the chain 4 is inserted into the steel pipe. The spacer 18 has a groove for passing the chain 4 at an eccentric position with respect to the central axis of the steel pipe 1, and the front pressing plate 2 and the spacer 18 are fixed by a spacer mounting jig 19.

The rear pressure plate 3 is integrated with the jack 5 and the steel pipe moving device 6 and moves on the rail 7 laid on the holding table 29 in the axial direction of the steel pipe 1. A heating coil 10 for heating the outer periphery of the steel pipe 1 includes a coil holder 11
And is connected to a heating device 12. The detailed configuration of the heating coil 10 is as shown in FIG. 12, and has the same structure and function as those in the first conventional example. The moving speed of the steel pipe moving device 6 can be adjusted by the steel pipe moving speed adjuster 16. The hydraulic jack 5 can adjust the hydraulic jack pulling force or the hydraulic jack pulling speed by the hydraulic jack pulling force adjuster 14 and the hydraulic jack pulling speed adjuster 15. The adjuster 17 adjusts the ratio between the jack pulling speed and the relative moving speed between the local heating unit and the steel pipe.

The heating temperature of the steel pipe 1 by the heating coil 10 and the temperature and amount of the cooling water 12 are controlled by control means (not shown).

The operation based on the above configuration in the case where one steel pipe is bent a plurality of times and bent into an S-shape will be described. (1) The first bending apparatus and method for bending one steel pipe shown in FIGS. 1 and 2 a plurality of times are the same as those of the conventional bending. Chain 4 by hydraulic jack 5
When a tensile force is applied between the fixed points at both ends of the steel pipe, the two fixed ends are on the eccentric axis of the steel pipe, so that the steel pipe 1 moves sequentially while receiving the compressive force in the eccentric axis direction. t
(See FIG. 12).

(2) As shown in FIGS. 3 and 4, after the first bending process is completed, the first bending process is performed with the axis of the pipe as the central axis.
Rotate the 80 ° bending tube. Although the present embodiment shows an example of a rotation angle of 180 °, the rotation angle can be set arbitrarily from 0 ° to 360 °.

(3) As shown in FIG. 5, the spacer 18 is inserted so that the tension axis of the chain is optimized.
It is fixed to the front pressure plate 2 with a spacer mounting jig 19.

(4) As shown in FIG. 5, bending is performed in the same manner as in (1).

(5) As shown in FIG. 6, an S-shaped bent tube is completed.

(Embodiment 2) FIG. 14 shows an embodiment of three-dimensional bending by the apparatus of Embodiment 2. The embodiment of the second method is realized by the steel pipe bending apparatus of this embodiment. In Example 1, after the first bending process,
Although the bent tube was turned 180 °, in Example 2, the bent tube was turned 90 ° after the first bending process. Next, the second bending process is performed by optimizing the tension axis of the chain.

Embodiment 3 In Embodiments 1 and 2, the spacer is inserted into the first bent portion.
The spacer can be inserted into a straight pipe to be bent.

[0031]

Since the present invention is configured as described above, it exhibits the following effects. Forming an annular local heating section around the steel pipe with its axis as the central axis, and moving the annular local heating section relative to the steel pipe in the axial direction of the steel pipe, the annular local heating section set on the eccentric axis of the steel pipe. When a bending moment is applied to the steel pipe by applying a tensile force between the points of action of the forces on both sides of the sandwiched steel pipe to bend the steel pipe, the tension axis of the tensile force applying means in the vicinity of the annular heating section is adjusted. Since the tension axis of the tensile force applying means is optimized by this means, S-shaped bending and three-dimensional bending can be easily performed.

[0032]

[Brief description of the drawings]

FIG. 1 is a plan view showing a state before bending in Example 1.

FIG. 2 is a plan view showing a state after bending in Example 1.

FIG. 3 is a plan view in which a bent tube is inverted after a first bending process in Example 1.

FIG. 4 is a plan view showing a state in which a front pressure plate of the first embodiment is removed.

FIG. 5 is a plan view showing a state in which the spacer of Example 1 is inserted, the chain is arranged at an optimum position, the front clamping plate is fixed to the chain and the spacer, and a state of the start of the second bending is shown.

FIG. 6 is a plan view showing a state in which the twelfth bending process has been completed and an S-shaped bent tube has been completed;

FIG. 7 is a plan view showing a state before a first bending process in a conventional bending device.

FIG. 8 is a plan view showing a state after a first bending process in a bending apparatus of a conventional example.

FIG. 9 is a plan view of a conventional bending apparatus in which a bending pipe is inverted after a first bending processing.

FIG. 10 is a plan view showing a state before a second bending process in the conventional bending apparatus.

FIG. 11 is a plan view showing a state where a tensile force is generated in a jack for the second bending by the conventional bending apparatus.

FIG. 12 is an enlarged sectional view of a heating coil and a steel pipe and a temperature distribution curve of a local heating part of the steel pipe.

FIG. 13 is an S-shaped bent elevation view of the first embodiment.

FIG. 14 is a three-dimensional bending elevation view of the second embodiment.

[Explanation of symbols]

Reference Signs List 1 steel pipe 2 front pressure plate 3 rear pressure plate 4 chain 5 jack 6 steel pipe moving device 7 rail 8 guide roller 9 guide roller 10 heating coil 10a annular flow passage h hole 11 coil holder 12 heating device 13 cooling water t annular local heating Part c Annular cooling section 14 Jack pulling force adjuster 15 Jack pulling speed adjuster 16 Steel pipe moving speed adjuster 17 Adjuster for ratio of jack pulling speed to steel pipe moving speed 18 Spacer 19 Spacer mounting jig 20 Chain fixing jig

Claims (2)

[Claims] 1. A heating means for annularly heating the periphery of a steel pipe around its axis as a center axis, a cooling means for annularly cooling an annular heating portion by the heating means around the axis of the steel pipe as a center axis,
First tensile force applying means for applying a tensile force between points of action of forces on both sides of the annular heating portion set on the first eccentric axis of the steel pipe, cooling the steel pipe, the heating means and Moving means for relatively moving the means in the axial direction of the steel pipe, the heating means, the cooling means, and the annular heating portion set on a second eccentric axis different from the first eccentric axis. Second tensile force applying means for applying a tensile force between the points of action of the forces on both sides of the steel pipe, and moving means for relatively moving the steel pipe, the heating means and the cooling means in the axial direction of the steel pipe. A steel pipe bending apparatus. 2. An annular local heating section around a steel pipe having its axis as a central axis is formed on an eccentric axis of the steel pipe while relatively moving the heating section relative to the steel pipe in the axial direction of the steel pipe. The first bending process is performed by applying a bending moment to the steel pipe by applying a tensile force between the points of action of the forces on both sides of the local heating section, and after the first bending processing, the bent pipe is removed. After rotating at an arbitrary angle about the axis as a central axis, an annular local heating portion having the axis as the central axis is formed around the steel pipe to be subjected to the second bending process, and this is heated in the axial direction of the steel pipe. While relatively moving, when applying a bending moment to the steel pipe by applying a tensile force between the points of action of the forces on both sides of the annular local heating section set on the eccentric axis of the steel pipe, The axis of action of the tensile force is a second eccentric axis A method of bending a steel pipe, wherein the second bending is performed by the second tensile force applying means set above.