JP2967482B1 - Steel pipe bending apparatus and method - Google Patents

Abstract

An object of the present invention is to reduce the thickness of a steel pipe due to bending and to reduce the size of the apparatus. SOLUTION: A heating means 10 for annularly heating the periphery of a steel pipe 1 around its axis as a center axis, a cooling means for annularly cooling an annular heating portion by the heating means about an axis of the steel pipe as a center axis, and eccentricity of the steel pipe 1 The tensile force applying means 25 for applying a tensile force between the points of action of the 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 relative to each other. A steel pipe bending apparatus comprising a driving means for moving.

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 (Conventional Example 1) FIG. 4 shows a steel pipe bending apparatus of Conventional Example 1. Bending of a steel pipe using this device is performed in the following manner.

(1) As shown in FIG. 4, a steel pipe 1 to be bent is placed on a support roller 2 and a pusher 4
The rear end is grasped by the tailstock 3 and the front end is grasped by the arm clamp 7 of the revolving arm 6 which revolves around the pivot 5.

(2) While guiding the steel pipe 1 with a pair of left and right guide rollers 8 and 9, the steel pipe 1 is pushed in the axial direction by a pusher 4, and is advanced toward the heating coil 10.
Pass through.

At this time, electricity is supplied to the heating coil 10 by the heating device 11.

Then, the steel pipe 1 is sequentially heated by the induction current from the heating coil 10. Heating coil 10
Is an annular coil, so that the periphery of the steel pipe 1 is annularly heated around its axis as a central axis.

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 number of holes h provided in the heating coil 10 in an annular arrangement. To go. 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 portion K having an axis as a central axis is sequentially formed in the steel pipe 1 as the steel pipe 1 advances. That is, the local heating unit K moves (reverses) 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. 3, the temperature of the heating zone having the width W in the axial direction is 760 ° C.
９００900 ° C.

(3) On the other hand, when the steel pipe 1 is pushed by the pusher 4 and moves forward, the turning arm 6 turns. When turning, the front end of the steel pipe 1 is fixed by the arm clamp 7, so that a bending moment is generated in the steel pipe 1, and the bending of the steel pipe 1 proceeds continuously.

At this time, if the turning speed of the turning arm 6 is made relatively slower than the moving speed of the steel pipe 1 by the pusher 4 so as to apply a brake to the moving of the steel pipe 1,
Since a compressive force acts on the steel pipe 1, it is possible to suppress the reduction in thickness of the steel pipe 1 due to bending.

(Conventional Example 2) FIG. 5 shows a steel pipe bending apparatus of Conventional Example 2. Bending of a steel pipe using this device is performed in the following manner.

(1) As shown in FIG. 5, a steel pipe 1 to be bent is placed on a support roller 2 and a pusher 4
Pusher 1 driven by a pusher 14 on the side of the front end portion, with the rear end of the
Hit 3.

(2) The steel pipe 1 is pushed in the axial direction of the steel pipe 1 by the pusher 4 while being guided by the pair of left and right guide rollers 8 and 9, is advanced toward the heating coil 10, and passes through the coil 10. .

At this time, the annular local heating section K is formed in the same manner as in the first conventional example.

(3) In this process, the front end of the advancing steel pipe 1 is pressed by the push roller 13. In this way, a bending moment is generated in the steel pipe 1, and the bending of the steel pipe 1 proceeds continuously.

At this time, the curvature of the steel pipe 1 is determined by the pressing force of the push roller 13 by the pusher 14 or the amount of advance.

[0018]

However, the conventional steel pipe bending apparatus has the following problems.

(1) Since the rigidity is increased in order to withstand the bending moment, the device becomes large and the weight becomes heavy. For this reason, the conventional apparatus is installed in a factory remote from the construction site, and the apparatus lacks portability.

Due to lack of portability, the following problems have occurred.

The steel pipe to be bent must be transported to a specific bending factory, bent, and then transported by truck or ship to a predetermined location in Japan and overseas. However, the bent steel pipe is bulky, so that the transportation efficiency is poor and the transportation cost is increased.

At a plant construction site or a pipeline laying site, the progress of the construction is delayed, and the piping design is changed or additional construction is performed. However, it is difficult to quickly respond to the above change at a pipe bending factory far from the site. It is.

There is a limit to the number of bendings that can be performed in one day by one bending apparatus. The reason for this is that the setup time is longer than the net bending time for a large variety of small products. There is no problem if the number of bending apparatuses is increased, but it is difficult to increase the number because the apparatus is large and expensive.

(2) The steel pipe is thinned by bending. In the case of Conventional Example 2, a compressive force can be applied to the steel pipe by applying a brake to the forward movement of the steel pipe in the process of bending the steel pipe by using the turning arm, so that the reduction in wall thickness can be suppressed to some extent.

However, in order to apply braking by the swing arm, the rigidity of the device must be greatly increased, so that the equipment cost becomes excessive and the device becomes large.

The present invention has been made in view of such technical background, and has an excellent portability of the apparatus and an apparatus and a method for bending a steel pipe capable of sufficiently suppressing wall thinning due to bending of the steel pipe. The purpose is to provide.

Another object of the present invention is to provide a steel pipe bending apparatus and method capable of sufficiently suppressing the reduction in wall thickness due to bending of a steel pipe.

[0028]

A steel pipe bending apparatus provided by the present invention is as described in the following (1) to (3).

(1) Heating means for annularly heating the periphery of the steel pipe around its axis as a center axis, cooling means for annularly cooling the annular heating portion by the heating means around the axis of the steel pipe as an axis, and eccentric axis of the steel pipe A 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 line, and the steel pipe, the heating means, and the cooling means are relatively moved in the axial direction of the steel pipe. A steel pipe bending apparatus (hereinafter, referred to as a first apparatus) comprising a driving means.

(2) A heating means for annularly heating the periphery of the 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 an axis, and an eccentric axis of the steel pipe. A 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 line, and the steel pipe, the heating means and the cooling means are relatively moved in the axial direction of the steel pipe. A steel pipe bending apparatus (hereinafter referred to as a second apparatus) comprising a driving means and a turning means for turning the front end of the steel pipe in a bending direction of the steel pipe when the steel pipe is moved forward in the axial direction. ).

(3) Heating means for annularly heating the periphery of the steel pipe around its axis as a center axis, cooling means for annularly cooling the annular heating portion by the heating means around the axis of the steel pipe as an axis, and eccentric axis of the steel pipe A 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 line, and the steel pipe, the heating means, and the cooling means are relatively moved in the axial direction of the steel pipe. A steel pipe bending apparatus (hereinafter, referred to as a third apparatus) comprising a driving means and a pressing force applying means for applying a pressing force in a bending direction to a steel pipe.

The steel pipe bending method provided by the present invention is described in the following (1) to (3).

(1) An annular local heating portion having its axis as a central axis is formed around the steel pipe, and a bending moment is applied to the heating portion while moving the local heating portion relative to the steel pipe in the axial direction of the steel pipe. When bending, the bending moment is applied by applying a tensile force between points of action of forces on both sides of the annular local heating portion set on the eccentric axis of the steel pipe. A characteristic method of bending a steel pipe (hereinafter, referred to as a first method).

(2) An annular local heating portion having its axis as a central axis is formed around the steel pipe, and a bending moment is applied to the heating portion while moving it relatively to the steel pipe in the axial direction of the steel pipe. When bending the steel pipe, when the bending moment, the tensile force applied between the action points of the forces on both sides of the annular local heating section set on the eccentric axis of the steel pipe, when the steel pipe advances A steel pipe bending method (hereinafter, referred to as a second method) characterized in that the method is applied by a turning force in a bending direction of the steel pipe applied to the front end thereof.

(3) An annular local heating portion having its axis as a central axis is formed around the steel pipe, and a bending moment is applied to the heating portion while moving this relative to the steel pipe in the axial direction of the steel pipe. When bending, the bending moment, the tensile force applied between the action points of the force on both sides of the annular local heating portion set on the eccentric axis of the steel pipe, and the steel pipe to be applied to the steel pipe And a pressing force in a bending direction of the steel pipe.
This is called the third method. ).

[0036]

(1) In the first to third devices and the fourth to sixth methods, when a bending moment is applied to a steel pipe, the point between two points of action of forces set on the eccentric axis of the steel pipe. Since a tensile force is applied to compress the steel pipe in the length direction, it is possible to suppress wall thinning due to bending of the steel pipe.

(2) In the first apparatus and the fourth method, only a tensile force is applied when a bending moment is applied to a steel pipe, so that the apparatus becomes small and light in weight. This is similar to the swing arm (swing means) in Conventional Example 1 or the pusher (pressing force applying means) in Conventional Example 2.
This is because it is not necessary to increase the size of the device and increase its weight because it is necessary to withstand a large bending moment. For this reason, transportation and installation of the device to the construction site are facilitated.

[0038]

Embodiments of the present invention will be described below with reference to embodiments.

(Embodiment 1) FIG. 1 shows an embodiment of the first apparatus. An embodiment of the fourth method is realized by the steel pipe bending apparatus of this embodiment.

In FIG. 1, reference numeral 1 denotes a carbon steel steel pipe, and reference numeral 2 denotes a support roller for supporting the steel pipe 1. Reference numeral 10 denotes a heating coil, and reference numeral 11 denotes a heating device, which has the same structure and function as those in the conventional examples 1 and 2. The detailed configuration is as shown in FIG. The heating coil 10 is attached to a driving device 22 that moves on a rail 21, and is moved in the axial direction of the copper tube 1 by the movement of this device.

Reference numerals 23 and 24 denote a front pressure plate and a rear pressure plate attached to the front end and the rear end of the steel pipe 1, respectively.

Reference numeral 25 denotes a hydraulic cylinder 25a and a chain 2
5b. The rod b of the hydraulic cylinder 25a is fixed to the rear pressing plate 24,
The front end a of the chain 25b is fixed to the front pressing plate 23.

The fixed point between the rod b, the fixed point and the chain is
It is set on the eccentric axis of the steel pipe 1 so as to be located on both sides of the annular heating part k by the heating coil 10. The two fixed points are driven in front of the hydraulic cylinder 25a,
It is the point of action of the pulling force by the chain pulling device 25 when pulling the rear holding plates 23, 24.

Reference numeral 26 denotes a holding table for fixing the steel pipe 1 at the rear holding plate 24. In a state where the steel pipe 1 is fixed by the holding table, the central axis of the heating coil 10 coincides with that of the steel pipe 1.

The control of the temperature of the heating coil 10, the movement of the drive unit 22, the temperature and amount of the cooling water 12, and the hydraulic pressure of the hydraulic cylinder 25a are performed by control means (not shown).

Next, the operation based on the above configuration will be described.

(1) When the hydraulic cylinder 25a is driven to apply a tensile force between the fixed points at both ends of the chain pulling device 25, the two fixed points are on the eccentric axis of the steel pipe 1.
While receiving the compressive force in the direction of the eccentric axis, the steel pipe 1 continuously bends toward the fixed point in the annular local heating portion K (see FIG. 6) that moves sequentially.

As described above, in the first embodiment, when a bending moment is applied to the local heating portion K, a compressive force acting on the copper tube 1 in the direction of its eccentric axis is applied. Can be reduced.

(2) When a bending moment is applied to the steel pipe, only the tensile force is applied by the chain pulling device 25, so that the device becomes small, light in weight and easy to carry. Therefore, it can be carried near the construction site and installed.

Therefore, the steel pipe to be bent can be processed at the construction site, and the transportation of the steel pipe before and after the processing is not required. In addition, even if a delay in the progress of construction or a change in piping design occurs, it can be promptly dealt with. Furthermore, since the setup of the bending process does not take much time, the number of steel pipes that can be bent per day increases.

(Embodiment 2) FIG. 2 shows an embodiment of the second apparatus. An embodiment of the fifth method is realized by the steel pipe bending apparatus of this embodiment.

The steel pipe bending apparatus according to the second embodiment is the same as that of the conventional example 1.
This is a configuration in which the apparatus of FIG. 4 (FIG. 4) and the apparatus of FIG. Therefore, the same or corresponding portions as those in FIGS. 1 and 4 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 2, 1 is a steel pipe, 2 is a support roller, 10 is a heating coil, 11 is a heating device, 23 is a front clamping plate, and 24 is a rear clamping plate. Reference numeral 25 denotes a chain pulling device, which comprises a hydraulic cylinder 25a and a chain 25b.

Reference numeral 6 denotes a swing arm which grips the front end of the steel pipe 1 with the clamp 7 and turns around the pivot 5. 8 and 9 are guide rollers for the steel pipe 1. 4 is steel pipe 1
, The steel pipe 1 gripped by the tailstock 3 via the rear holding plate 24 is driven forward in the axial direction.
Therefore, in the second embodiment, the heating coil 10 is installed at a fixed position.

The control of the temperature of the heating coil 10, the temperature and the amount of the cooling water 12, and the hydraulic pressures of the pusher 4 and the hydraulic cylinder 25a are performed by a control device (not shown).

In the second embodiment, as in the first embodiment, when a bending moment is applied to the annular local heating portion K, a compressive force acting in the direction of the eccentric axis is applied to the steel pipe 1, so that the steel pipe 1 is bent. The thickness loss at the time can be suppressed.

Since the turning arm 6 applies a turning force to the front end of the steel pipe 1 with a constant radius of curvature, the bending accuracy of the steel pipe 1 can be maintained with high accuracy.

(Embodiment 3) FIG. 3 shows an embodiment of the third apparatus. An embodiment of the sixth method is realized by the steel pipe bending apparatus of this embodiment.

The steel pipe bending apparatus according to the third embodiment is similar to the conventional second embodiment.
This is a configuration in which the device of FIG. 5 (FIG. 5) is combined with the device of FIG. Therefore, the same or corresponding parts as those in FIGS. 1 and 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 3, 1 is a steel pipe, 2 is a support roller, 10 is a heating coil, 11 is a heating device, 23 is a front clamping plate, 24 is a rear clamping plate, 25 is a chain tensioning device, and 25 is a hydraulic cylinder 25a. It is composed of a chain 25b.

Reference numeral 13 denotes a push roller which is pushed by the pusher 14 and presses the steel pipe 1 in a bending direction (toward the chain tensioning device). Reference numerals 8 and 9 denote guide rollers for the steel pipe 1.

4 is a pusher for the steel pipe 1,
The steel pipe 1 gripped by the tailstock 3 via 4 is driven forward in its axial direction. Therefore, in the third embodiment, the heating coil 10 is installed at a fixed position.

The control of the temperature of the heating coil 10, the temperature and amount of the cooling water 12, and the hydraulic pressures of the pusher 4, the pusher 14, and the hydraulic cylinder 25a are performed by a control device (not shown).

In the third embodiment, similarly to the first embodiment, when a bending moment is applied to the local heating portion K, a compressive force acting in the direction of the eccentric axis is applied to the steel pipe 1.
It is possible to suppress the wall thickness loss when bending.

Further, since a pressing force is applied to the front end portion of the steel pipe 1 by the push roller 13 at a constant advance amount, the bending accuracy of the steel pipe 1 can be maintained with high accuracy.

In the first embodiment, the steel tube 1 is fixed at a fixed position and the heating coil 10 is moved. However, the opposite configuration may be adopted, or the two members 1 and 10 are simultaneously moved relative to each other. It may be configured. In the second and third embodiments, the heating coil 10 is fixed at a fixed position. However, the heating coil 10 may be moved relative to the steel pipe 1.

In the first to third embodiments, the heating means (heating coil 10) is provided integrally with the cooling means (the water flow passage 10a and the hole h of the cooling water 12). Can be controlled separately.

[0068]

(1) In the first to third devices and the fourth to sixth methods, as described above, when a bending moment is applied to a steel pipe, the two pipes set on the eccentric axis of the steel pipe are used. Since a tensile force is applied between the points of force to compress the steel pipe in the length direction, the elongation due to bending of the steel pipe is suppressed,
It is possible to suppress wall thinning of the steel pipe.

(2) In the first device and the fourth method, as described above, only a tensile force is applied when a bending moment is applied to a steel pipe. Therefore, the device becomes small and lightweight. The equipment can be easily transported to the construction site and installed. For this reason, efficient bending of the steel pipe in response to the progress of the construction and the design change becomes possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a steel pipe bending apparatus according to a first embodiment.

FIG. 2 is a transverse sectional view of a steel pipe bending apparatus according to a second embodiment.

FIG. 3 is a cross-sectional view of a steel pipe bending apparatus according to a third embodiment.

FIG. 4 is a plan view of a steel pipe bending apparatus of Conventional Example 1.

FIG. 5 is a plan view of a steel pipe bending apparatus of Conventional Example 2.

FIG. 6 is an enlarged sectional view of a heating coil and a steel pipe in FIGS. 4 and 5, and a temperature distribution curve of a local heating part of the steel pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Support roller 3 Tail stock 4, 14 Pusher 5 Pivot 6 Swivel arm 7 Arm clamp 8, 9 Guide roller 10 Heating coil 10a Annular flow path h hole 11 Heating device 12 Cooling water k Annular heating part c Annular cooling part K Annular Local heating section 13 Push roller 21 Rail 22 Drive unit 23 Front clamping plate 24 Rear clamping plate 25 Chain tensioning device 25a Hydraulic cylinder 25b Chain 26 Holder

Claims (6)

(57) [Claims] 1. A heating means for annularly heating the periphery of a steel pipe around its axis as a center axis, and a cooling means for annularly cooling an annular heating portion by the heating means about the axis of the steel pipe as a center axis;
A 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 eccentric axis of the steel pipe, and the steel pipe, the heating means, and the cooling means in the axial direction of the steel pipe. And a driving means for relatively moving the steel pipe. 2. 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 about the axis of the steel pipe as a center axis,
A 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 eccentric axis of the steel pipe, and the steel pipe, the heating means, and the cooling means in the axial direction of the steel pipe. And a turning means for turning the front end of the steel pipe in the bending direction of the steel pipe when the steel pipe is moved forward in the axial direction. 3. A heating means for annularly heating the periphery of the steel pipe around its axis as a center axis, a cooling means for annularly cooling an annular heating portion by the heating means about the axis of the steel pipe as a center axis,
A 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 eccentric axis of the steel pipe, and the steel pipe, the heating means, and the cooling means in the axial direction of the steel pipe. And a pressing means for applying a pressing force in the bending direction to the steel pipe. 4. An annular local heating portion having its axis as a center axis is formed around a steel pipe, and a bending moment is applied to the heating portion while moving the heating portion relative to the steel pipe in the axial direction of the steel pipe. When bending, the bending moment,
A method of bending a steel pipe, wherein a tensile force is applied between application points of forces on both sides of the annular local heating section set on the eccentric axis of the steel pipe, thereby applying the tensile force. 5. An annular local heating section around the steel pipe having its axis as a central axis is formed around the steel pipe, and a bending moment is applied to the heating section while moving the heating section relatively to the steel pipe in the axial direction of the steel pipe. When bending, the bending moment,
A tensile force applied between the action points of the forces on both sides of the annular local heating portion set on the eccentric axis of the steel pipe,
A method for bending a steel pipe, characterized in that when the steel pipe advances, the steel pipe is applied by a turning force in a bending direction of the steel pipe applied to a front end thereof. 6. An annular local heating portion having its axis as a central axis is formed around a steel pipe, and a bending moment is applied to the heating portion while moving the local heating portion relative to the steel pipe in the axial direction of the steel pipe. When bending, the bending moment,
A tensile force applied between the action points of the forces on both sides of the annular local heating portion set on the eccentric axis of the steel pipe,
A method for bending a steel pipe, wherein the method is applied by applying a pressing force to the steel pipe in a bending direction of the steel pipe.