JP2002346641A - Bending apparatus for hollow jacketed pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perfectly bend a hollow double pipe consisting of an outer and an inner pipes, keeping an aperture between both pipes. SOLUTION: A bending device A is comprised of a mandrel 11 with a forming section 11c at its top, jig 12 which has multiple strip pieces 17 arranged parallel in a ring shape, a guide member 13 to guide the jig 12 into the aperture 3 of the double pipe B, and a die 14 which contacts with the outer periphery of outer pipe 1 of the double pipe and performs bending work. In the jig 12, which is inserted into the aperture 3 formed between the outer pipe 1 and the inner pipe 2 of the double pipe B, strip pieces 17 on the inner side and the outer side of the bending direction are composed by stacking multiple thin strip pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow double tube composed of an outer tube and an inner tube, wherein a hollow double tube having a predetermined gap formed between these tubes can be smoothly bent. The present invention relates to a heavy pipe bending apparatus.

[0002]

2. Description of the Related Art For example, a tube arranged so as to eliminate heat exchange with the atmosphere typified by a tube arranged in an exhaust system of an internal combustion engine is provided inside the outer tube. By inserting an inner tube capable of forming a predetermined gap between the outer tube and the inner tube, the outer tube and the inner tube are fixed to each other at at least one end, so that both tubes are arranged substantially concentrically and a space between both tubes is provided. Is formed as a so-called hollow double tube in which a gap is formed. Particularly, in an exhaust pipe of an internal combustion engine for an automobile, the exhaust pipe is arranged along an exhaust path preset according to a layout of a target automobile, and thus is bent into a shape corresponding to the exhaust path.

When bending a hollow double tube, a core is inserted into the inner tube, and a gap formed between the outer tube and the inner tube is filled with a filler. As the object, a granular material such as sand or a small-diameter steel ball is used. However, when the filling is sand or steel balls, the operation of removing the filling from the gap between the outer tube and the inner tube after the bending of the hollow double tube is completed, and eliminating the filling. There is a problem that the amount of work such as cleaning the hollow double pipe after the cleaning is large. For this reason, recently, a technique for inserting an object instead of a granular material into a gap formed between the outer tube and the inner tube has been proposed.

[0004] For example, a technique (first known example) disclosed in Japanese Patent Application Laid-Open No. 8-276222 relates to a method of bending a hollow double pipe, and a gap formed between an outer pipe and an inner pipe. To
After filling a plurality of rod-shaped linear wires, bending is performed. This technique has the effect of shortening the cycle time.

A technique disclosed in Japanese Patent Application Laid-Open No. 10-71430 (second known example) relates to a bending apparatus for a hollow double pipe, and has a rigid tubular shape having a gap between an inner pipe and an outer pipe. It is configured to perform bending by inserting a cored bar. A chamfered portion having substantially the same shape as the final bent shape of the inner and outer tubes is formed at an end of the tubular cored bar. According to this technique, the inner and outer tubes can be smoothly and satisfactorily bent along the chamfered portion of the annular cored bar.

[0006]

In the first known example,
Although a plurality of straight wires can maintain their positions independently of each other, the wire is initially filled in the space formed between the outer tube and the inner tube, but while it is kept filled with the space, With the progress of the bending process, the wires filled in the outer side in the bending direction are displaced and escape to the side in the bending direction, and the inner and outer tubes come into contact without being able to perform a good bending process. May occur.

In the second known example, a chamfer having substantially the same shape as the final bent shape of the inner and outer tubes is formed on the free end side of the annular core inserted into the gap between the inner and outer tubes. In particular, since the annular cored bar is formed by a tube having a wall thickness smaller than the dimension of the gap between the inner tube and the outer tube, the strength of the distal end portion may be insufficient. If a slit is formed on the free end side of the annular core, bending of the free end portion is allowed, but this deflection may remain as permanent deformation. In this case, the deformed annular core May not be reusable.

An object of the present invention is to provide a bending apparatus capable of performing a good bending process on a hollow double tube while maintaining a gap between an outer tube and an inner tube.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a hollow double pipe bending apparatus according to the present invention is provided with a gap formed between the outer pipe and the outer pipe. A bending apparatus for bending a hollow double pipe, in which a jig is inserted into the gap and inserting a jig into the gap, with a bending die, wherein a gap formed between the outer pipe and the inner pipe is provided. The jig to be inserted into a plurality of belt-like plates is formed by arranging a plurality of elastic band-shaped plates in a ring.

[0010] The above hollow double pipe bending apparatus (hereinafter, referred to as a bending apparatus).
In the “bending device”, the jig inserted into the gap between the outer pipe and the inner pipe is formed by arranging a plurality of elastic strips in a tubular shape. Into a hollow double pipe (hereinafter referred to as “double pipe”)
), The jig is deformed following the progress of the bending process, whereby the bending process for the double pipe can be performed smoothly.

In particular, when a bending force acts on the strips disposed on the inner and outer sides in the bending direction as the bending process proceeds, the jig is formed by arranging the strips in a ring shape. Therefore, the adjacent belt-like plates come into contact with each other, so that even if the above-mentioned force acts, they do not shift to the side surfaces. Therefore, the insertion position with respect to the gap between the outer tube and the inner tube can be reliably maintained, and favorable bending can be performed.

In the above bending apparatus, it is preferable that at least the strips arranged on the inner side and the outer side in the bending direction are formed by stacking a plurality of thin strips. Is preferably tapered. Further, it is preferable that the belt-like plate is made of spring steel.

[0013] In a bending apparatus in which at least the inner peripheral side and the outer peripheral side in the bending direction are band-shaped plates in which a plurality of thin band-shaped plates are stacked, the bending rigidity of each thin band-shaped plate is reduced, and high follow-up performance can be exhibited. I can do it. For this reason, the concentration of stress can be reduced and the frequency of repeated use can be improved. In addition, by making the free ends of the strips tapered, the free ends interfere with each other even when the strip on the side in the bending direction approaches another adjacent strip with the progress of bending. A smooth bending process can be realized without any.
Further, when the belt-like plate is made of spring steel, high elasticity can be exhibited, and the frequency of repeated use can be improved.

Further, in the bending apparatus, it is preferable to provide a cylindrical guide member which can reciprocate along the axial direction of a jig formed by arranging a plurality of band-shaped plates in a ring.
In the bending apparatus provided with such a guide member, the operation when the double pipe is mounted on the bending apparatus can be performed smoothly. That is, a plurality of band-shaped plates arranged in a ring are held by the cylindrical guide member, and after maintaining the state, the double pipe is mounted and then moved in the axial direction, so that the outer pipe in the double pipe is moved. The jig can be easily inserted into the gap between the pipe and the inner pipe.

Further, in the bending apparatus, the core bar inserted into the inner tube and the jig inserted into the gap formed between the outer tube and the inner tube move independently of each other. It is preferably configured to obtain In the bending apparatus configured as described above, with the progress of bending,
It is possible to selectively move the core metal inserted inside the inner tube and the jig inserted in the gap between the outer tube and the inner tube,
For example, after the bending process for the double pipe is completed, the core metal is moved alone to separate from the bent double pipe, and then the jig is released separately from the double pipe to complete the bending process. Work to remove the bent double pipe from the bending machine,
And the work of attaching to the bending device can be easily and smoothly progressed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A bending apparatus according to the present invention realizes smooth and reliable bending of a double pipe used as an exhaust pipe of an engine, for example. At the same time, insert a jig formed by arranging a plurality of elastic band-shaped plates annularly side by side in the gap formed between the outer tube and the inner tube, and further bend the outer periphery of the outer tube. By constraining and bending with a die (die), the gap between the outer tube and the inner tube can be maintained in a substantially constant state, and good bending can be realized.

In particular, when a large force acts on the strip inserted in the gap between the inner and outer sides in the bending direction with the progress of the bending process, the freedom of movement of the strip is limited to that of the other adjacent strip. It is constrained by the band-shaped plate, thereby exhibiting the function of maintaining the initial arrangement position and maintaining the gap between the outer tube and the inner tube, thereby achieving good bending.

Hereinafter, a preferred embodiment of the bending apparatus will be described with reference to the drawings. FIG. 1 is a diagram showing a main part of the bending apparatus. 2A and 2B are diagrams showing the relationship between the cored bar and the jig, wherein FIG. 2A is a side view and FIG. 2B is a plan view. FIG. 3 is a plan view illustrating the arrangement of the jig. FIG. 4 is a diagram illustrating a state in which a double pipe is mounted on a cored bar and a jig. FIG. 5 is a perspective view illustrating the configuration of the double pipe.

First, before describing the bending apparatus A,
The configuration of the double pipe B bent by the bending apparatus A will be described with reference to FIG. The double pipe B shown in the figure is used for an exhaust system of an automobile engine, and describes a straight tubular intermediate product.

A double pipe B is inserted into an outer pipe 1 having a preset diameter and an inner pipe 2 having a preset diameter, and a gap 3 is provided between the two pipes 1 and 2. And an enlarged portion 2a obtained by enlarging one end of the inner tube 2 is brought into contact with the inner surface of the outer tube 1 and the two tubes 1 and 2 are fixed by means such as welding. Have been.

The double pipe B is bent in accordance with the shape of a preset arrangement position in the exhaust system of the engine, and flows while maintaining the temperature of the exhaust gas exhausted from the engine in a high state. Has functions.

Next, the configuration of the bending apparatus A is shown in FIG.
This will be described with reference to FIG. In the figure, bending equipment A
Are a plurality of cores 11 inserted into the inner tube 2 of the double tube B, and a plurality of elastic and annularly parallel inserted in the gap 3 formed between the outer tube 1 and the inner tube 2. Jig made of strip-shaped plate 17
12 and a jig 12 when attaching the double pipe B to the bending apparatus A.
A guide member 13 having a function of introducing the outer tube 1 into the gap 3, and a die 14 for restraining the outer periphery of the outer tube 1 and performing bending.

The core metal 11 abuts on the inner peripheral surface of the inner pipe 2 when bending the double pipe B, and restricts the core pipe 11 when the double pipe B is mounted on the bending apparatus A. Jig in the gap of heavy pipe B
It has a function of guiding the movement of a guide member 13 into which the insertion member 12 is inserted, and has a molding member 11a provided at a distal end portion (free end portion) and a connection member for connecting the molding member 11a to the main body
11b.

At the tip of the forming member 11a, a curved forming portion 11c having an outer diameter substantially equal to the inner diameter of the inner tube 2 and corresponding to a desired bending angle is formed. The formed portion 11c performs a bending process by sliding and restraining the inner peripheral surface of the inner tube 2. Therefore, the molded portion 11c is configured so that the lubricant supplied through the cored bar 11 can be leached so as to reduce frictional resistance, and is subjected to a surface treatment to reduce wear. I have. Also, the connecting member 11b of the molded part 11c
A shaft portion 11d is formed on the side, and a screw portion 11e for connecting the connection member 11b is formed at the center of the shaft portion 11d. The outer circumference of the shaft portion 11d functions as a guide portion for guiding the movement of the guide member 13.

The connecting member 11b has a function of connecting the forming member 11a to the main body (not shown) of the bending apparatus A and a function as a guide for guiding the movement of the guide member 13, and has a longitudinal direction. End on one side (end on molding member side)
Is formed with a screw portion 11f screwed to the screw portion 11e of the molding member 11a, and a screw portion 11g to which a screw (not shown) for connecting to the main body portion is screwed to the other end (the main body side end). Are formed.

A male screw 11h is formed near the end on the main body side and on the outer periphery, and a ring member is attached to the male screw 11h.
15 and nut 16 are integrated and fastened. Then, the core 11 and the jig 12 are attached to the main body by screwing the screw portion 11g to a screw provided on the main body of the bending apparatus A.

The jig 12 is inserted into a gap 3 formed between the outer pipe 1 and the inner pipe 2 constituting the double pipe B to restrict the gap between the two pipes 1 and 2 in the gap 3. This prevents deformation (for example, buckling) of the two pipes 1 and 2 in an unmanaged state due to the progress of the bending process, thereby realizing a good bending process. ) Is fixed to the outer periphery of the ring member 15 screwed to the end of the core metal 11 on the main body side by a bolt 15a, and the other end (free end) substantially coincides with the tip end of the molding member 11a of the core metal 11. A plurality of strips 17 arranged at positions where
Are annularly arranged in parallel.

The belt-like plate 17 constituting the jig 12 is made of a relatively thin plate having elasticity and having a predetermined width and thickness. Therefore, when the bending of the double pipe B is completed and the double pipe B is removed from the bending apparatus A, the band-shaped plate 17 returns to the original straight shape, and prepares for the next bending. Can be

When the jig 12 is inserted into the gap 3 of the double pipe B to perform the bending, the band-like plate 17 is moved with the progress of the bending.
Is deformed. In particular, the inner peripheral side in the bending direction (the core metal shown in FIG. 1)
In the strip-shaped plate 17 arranged on the die 14 side of the forming member 11a in 11 and the same hereinafter, and on the outer peripheral side (the forming portion 11c side of the core shown in FIG. 1 and the same hereinafter), according to the intended bending radius. Bending will occur. For this reason, the band-like plate 17 needs to have a flexible flexibility, and any material having such properties can be used.

In particular, it is preferable that the belt-like plates 17 arranged on the inner and outer peripheral sides in the bending direction and in the vicinity thereof can flexibly follow the bending. In this case, good compliance with bending can be exhibited by reducing the thickness of the band-shaped plate 17, but the size of the gap 3 between the outer tube 1 and the inner tube 2 is only achieved by simply arranging a thin band-shaped plate. Cannot be maintained. That is, the thickness of the band-shaped plate needs to be substantially equal to the dimension of the gap 3. For this reason, the band-shaped plate arranged on the inner and outer peripheral sides in the bending direction
Reference numeral 17 denotes a thickness corresponding to the size of the gap 3 by laminating a plurality of thin plates having elasticity.

In the present embodiment, the belt-like plate 17 has a thickness of 0.
5mm spring steel and 1.5mm thickness spring steel are selectively used. As shown in Fig.3, 0.5mm thin springs are provided on the inner and outer sides in the bending direction. Four sets of strip-shaped plates 17 each consisting of three steel layers (eight sets for jig 12)
The core metal 11 shown in FIG.
In the vertical direction of the formed member 11a in the above, the same applies hereinafter), two strip-shaped plates 17 each made of a single piece of spring steel having a thickness of 1.5 mm are provided.
Sets (four sets as jigs 12) are arranged.

Accordingly, the jig 12 is composed of twelve sets of band-shaped plates 17 arranged in a ring, and on the side surface in the bending direction, the bolt 18 of the guide member 13 is moved between the band-shaped plates 17 made of a thick plate. An allowable gap 19 is formed. Also, the jig 12 is made of one spring steel or three spring steels depending on an arrangement portion.
It is constituted by a plurality of strip-shaped plates 17 each having the same apparent thickness.

It is to be noted that the band-shaped plate 17 is not necessarily limited to a spring steel, but an elastic material can be used. As such a material, a non-ferrous material having elasticity represented by a phosphor bronze plate can be used.

The belt-like plates 17 which are arranged side by side and constitute the jig 12
Is not particularly limited. However, when the width dimension is reduced, the deformation in the width direction becomes easy, and it may interfere with another adjacent strip-shaped plate 17 to cause a problem similar to that of the first known example. For this reason, it is preferable to set the width of the strip 17 in consideration of the circumferential length of the gap 3 in the double pipe B.

In the present embodiment, there is a gap such that adjacent strip-shaped plates 17 are in contact with each other on the inner circumferential side and the outer circumferential side in the bending direction, or are easily in contact with each other when deformed as the bending process proceeds. Thus, twelve strip-shaped plates 17 are arranged. Therefore, when a bending force is applied to the band-shaped plate 17 when bending the double pipe B, and when the band-shaped plate 17 is deformed in accordance with the bending force, the deformed band-shaped plate 17 is connected to another adjacent band-shaped plate. It comes into contact with 17 and can maintain its own position.

On the side of the jig 12 in the bending direction, when the guide member 13 is reciprocated along the guide portion formed by the shaft portion 11d of the molded member 11a of the cored bar 11 and the connecting member 11b. A gap 19 that allows the bolt 18 provided on the guide member 13 to move is formed (particularly, see FIG. 3). That is, a jig
The band-shaped plate 17 forming the part 12 is arranged with a gap 19 formed on the side surface in the bending direction, and is fixed to the ring member 15.

The ring member 15 is integrally formed with a nut 16 at the end on the main body side, and is screwed to a male screw 11h formed on a connecting member 11b constituting the metal core 11, and is rotated with respect to the metal core 11. A belt-like plate 17 constituting the jig 12 is formed on the outer peripheral surface so as to be possible.
Is fixed. As described above, the ring member 15 is not integrated with the cored bar 11 and is allowed to rotate and move in the axial direction. That is, the metal core 11 and the jig 12 fixed to the ring member 15 can move independently of each other.

Accordingly, a ring member 15 and a nut 16 in which the jig 12 is fixed to the screw portion 11h formed on the connection member 11b of the cored bar 11 are provided.
By adjusting the positions of the molding portion 11c and the die 14 in this state, the core 11 and the die 14, and the core 11 and the jig are adjusted.
By setting a relative position in the axial direction with respect to 12 and preventing the nut 16 from rotating with a hollow set bolt or the like, the set position can be maintained.

By rotating the ring member 15 and the nut 16, the cored bar 11 can be relatively moved in the axial direction. That is, by rotating the ring member 15 and the nut 16 while the core metal 11 is restrained, the jig 12 can be moved to the die 14 side. In a case where the core bar 11 is restrained while being inserted into the gap 3 of the heavy pipe B, the core metal 11 can be moved to the main body side.

For this reason, after the bending of the double pipe B is completed, when the double pipe B is detached from the bending apparatus A, the nut 16 is rotated to rotate the formed member 11a from the inner pipe 2. The detachment of the metal core 11 and the detachment of the jig 12 from the gap 3 can be performed in order, which is advantageous because a large force is not required at one time and an easy operation is achieved.

The outer peripheries of the plurality of band-shaped plates 17 attached to the ring member 15 are fastened by split nuts 20. The split nut 20 has a function of bundling a plurality of band-shaped plates 17 and making the band-shaped plates 17 which are flat in an individual state as a whole an annular shape. Therefore, each strip 17 is
Although attached to the ring member 15 by one bolt 15a, it is firmly fixed by the split nut 20. Each band-like plate 17 is formed in an arc shape by the outer periphery of the ring member 15 and the inner periphery of the split nut 20.

When the jig 12 is inserted into the gap 3 of the double pipe B and bending is performed, the portion corresponding to the forming member 11a of the strip 17 disposed on the side in the bending direction is the strip. There is a possibility that bending occurs in the width direction of the 17 and the free ends of the adjacent strips 17 interfere with each other. For this reason, the free end portion of the band-shaped plate 17, especially the band-shaped plate 17 arranged on the side surface in the bending direction is formed in a tapered shape (see FIG. 3). The tapered shape of the free end portion of the band-shaped plate 17 is such that the width dimension is inclined so that the dimension in the width direction decreases toward the free end, and that the corner in the width direction at the free end portion has an arc shape. In some cases, it is formed, and in other cases, the entire free end portion is formed in an arc shape, and these are all included.

When the double pipe B is mounted on the bending apparatus A, the guide member 13 is used for the jig 12 with respect to the gap 3 of the double pipe B.
It has a function to easily insert the. Therefore, the guide member 13 has an outer sleeve 13a having an inner diameter substantially equal to the outer tube 1 and an inner sleeve 13b having an outer diameter substantially equal to the outer diameter of the inner tube 2. , 13b
Are connected by bolts 18, so that both sleeves 13a,
A gap 13c for inserting the jig 12 is formed between 13b. Therefore, the gap 13c of the guide member 13 is a double pipe B
Are formed to have dimensions substantially equal to the gap 3 of.

At the end of the inner sleeve 13b on the main body side, a core metal
11. Outer periphery of shaft 11d of molded member 11a and connecting member
A flange 13e having a hole 13d fitted on the outer periphery of 11b is provided so that the guide member 13 can reciprocate along the metal core 11.

That is, when configuring the bending apparatus A, the inner sleeve 13b is previously fitted to the connecting member 11b of the cored bar 11, and then the forming member 11a is connected to the connecting member 11b. A plurality of strips 17 are arranged on the outer periphery of the ring member 15 and fixed by bolts 15a. At this time, the jig 12 including a plurality of band-shaped plates 17 arranged in a ring is attached to the inner sleeve.
13b is arranged on the outer peripheral surface. Further, the outer sleeve 13a is fitted to the outer periphery of the plurality of band-shaped plates 17 arranged in a ring,
The two sleeves 13a and 13b are integrated by 18. In particular,
The outer peripheral surface of the inner sleeve 13b and the vicinity of the position of the bolt 18 or the inner peripheral surface of the outer sleeve 13a and the bolt 18
By providing, for example, a protrusion or the like that can regulate the size of the gap 13c in the vicinity of the disposition portion, the size of the gap 13c can be maintained.

In the guide member 13 configured as described above,
As shown in FIG. 2A, when the guide member 13 is moved toward the forming portion, a plurality of band-shaped plates constituting the jig 12 are provided in a gap 13c formed between the outer sleeve 13a and the inner sleeve 13b.
17 can be accommodated in a state of being arranged in a ring. Then, as shown in FIG.
Side, the outer tube 1 of the double tube B faces the outer sleeve 13a, and the inner tube 2 faces the inner sleeve 13b. By moving the tube B toward the main body, the gap between the guide members 13 is reduced.
The jig 12 housed in 13c can be inserted into the gap 3 of the double pipe B.

The die 14 is not functionally different from a die generally used in the past. The die 14 has a bending piece 14a for setting a bending radius in contact with the outer periphery of the double pipe B, and a double pipe B. Fixing member 14b for fixing the end of the member to the bending piece 14a
And a restricting member 14c for restricting the moving direction of the double pipe B.

Then, the double pipe B is mounted on the die 14, the end of the double pipe B is fixed to the bending piece 14a by the fixing member 14b, and the bending piece 14b is driven by a driving member (not shown) to rotate clockwise. By rotating the double pipe B, the double pipe B can be bent in accordance with the radius of the bending piece 14a and the diameter of the double pipe B.

Next, a brief description will be given of a procedure for bending the double pipe B by the bending apparatus A configured as described above. The bending apparatus A is configured with the jig 12 inserted into the gap 13c formed between the inner sleeve 13b and the outer sleeve 13a, as described above, and the bolt 18 of the guide member 13 Is inserted into a gap 19 formed between a plurality of band-shaped plates 17 constituting the jig 12. The forming member 11a of the core metal 11 is set at a position corresponding to the bending piece 14a of the die 14 when performing the bending process.

First, the guide member 13 is connected to the molding member 11 of the metal core 11.
The outer tube 1 of the double tube B is made to face the outer sleeve 13a and the inner tube 2 is made to face the inner sleeve 13b in this state. Next, when the guide member 13 and the double pipe B are simultaneously moved to the main body side, the jig 12 accommodated in the gap 13c of the guide member 13 is moved.
Is inserted into the gap 3 of the double pipe B as it is.
Therefore, the jig 12 can be inserted into the gap 3 of the double pipe B by moving the guide member 13 to a position close to the split nut 20. At this time, the double tube B is
Is inserted through the inside of the restraining member 14c.

Next, the outer periphery of the double pipe B is brought into contact with and fixed to the bending piece 14a by operating the fixing member 14b of the die 14, and in this state, a driving member (not shown) is operated to rotate the bending piece 14a. Then, the double pipe B is bent along the outer periphery of the bending piece 14a and bent at a predetermined curvature.

At this time, the individual band-shaped plates constituting the jig 12
Complex forces such as bending force and torsion force are applied to the 17 due to the bending process, but since these belt-like plates 17 are arranged in a ring, the adjacent belt-like plates even at the free end side The widthwise ends of the strips 17 are in contact with each other, and adjacent strips 17 do not overlap. Accordingly, the jig 12 maintains the thickness of the band-shaped plate 17, thereby making it possible to maintain the size of the gap 3 between the double tubes B.

When the bending process on the double tube B is completed, the forming part 11c of the core metal 11 is kept in contact with the inner peripheral surface of the inner tube 2 of the double tube B, and the jig 12 is It is deformed in the housed state. The detachment of the double pipe B from the bending apparatus A in this state is performed by moving the double pipe B straight along the axis of the cored bar 11. However, the molding part 11c
There is a close contact between the inner pipe 2 and the inner peripheral surface of the inner pipe 2, a deformation in the gap 3 of the jig 12, and the like, and a large force is required to separate the double pipe B.

For this reason, by rotating the nut 16 screwed into the threaded portion 11h of the connecting member 11b, the cored bar 11 is moved to the main body side without rotating, whereby the forming member 11
a can be removed from the die 14. That is,
By rotating the nut 16, an axial force is applied to the ring member 15, and the reaction of the force causes the core metal 11 to be attached to the jig 12.
Can be moved to the main body side independently from the main body.

Accordingly, the contact of the forming portion 11c with the inner tube 2 is released, and the double tube B having been bent is finished.
, Only the jig 12 is inserted. For this reason,
By pulling the double tube B that has been bent, the gap 3
The double pipe B can be removed from the bending apparatus A by easily detaching the jig 12 inserted in the bending apparatus A.

After removing the double tube B which has been bent as described above, the nut 16 is restrained while the rotation of the cored bar 11 is restrained.
Is rotated, whereby the molding member 11a can be moved to the molding portion side and returned to the position corresponding to the die 14.

[0057]

As described above in detail, in the bending apparatus according to the present invention, a plurality of band-shaped plates are annularly juxtaposed to constitute a jig. Even when a force is applied, the strips abut on the strips adjacent to each other and are restrained, so that the initial position can be maintained. For this reason, the dimension of the gap between the outer tube and the inner tube in the double tube is maintained by the band-shaped plate, and good bending can be performed.

Also, since the strip has elasticity, after the bending of the double pipe is completed and the double pipe is separated from the bending apparatus, the strip easily returns to its initial shape and is reused. You can do it.

Further, since the strips arranged on the inner and outer peripheral sides in the bending direction are formed by laminating thin plates, these strips can exhibit great elasticity, and can be reused without concentration of stress. I can do it. In addition, by using spring steel as the belt-like plate, good restorability and durability can be exhibited.

By providing a guide member for introducing the jig into the gap between the double pipes, even if the jig is composed of a plurality of strips, it can be very easily inserted into the gap formed in the double pipe. Can be done.

Since the mandrel and the jig can move independently of each other, after the bending of the double tube is completed, the mandrel is removed from the bent portion, and then the jig is removed from the bent double tube. The tool can be removed. For this reason, the friction is reduced, and the operation can be easily performed without requiring a large force.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main part of a bending apparatus.

FIGS. 2A and 2B are diagrams showing a relationship between a cored bar and a jig; FIG. 2A is a side view, and FIG.

FIG. 3 is a plan view illustrating an arrangement of a jig.

FIG. 4 is a diagram illustrating a state in which a double tube is mounted on a cored bar and a jig.

FIG. 5 is a perspective view illustrating a configuration of a double pipe.

[Explanation of symbols]

 A Bending apparatus B Double pipe 1 Outer pipe 2 Inner pipe 2a Large diameter part 3 Gap 11 Core 11a Molded member 11b Connection member 11c Molded part 11d Shaft part 11e, 11f Screw part 11h Male screw 12 Jig 13 Guide member 13a Outer sleeve 13b inner sleeve 13c gap 13d hole 13e flange 14 die 14a bending piece 14b fixing member 14c restraining member 15 ring member 15a bolt 16 nut 17 band plate 18 bolt 19 gap 20 split nut

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F01N 7/18 F01N 7/18 (72) Inventor Kiyoyo Sugiyama 49-2 Shantou, Tenryu-shi, Shizuoka 2 Co., Ltd. F-term in SMILEX (reference) 3G004 DA14 GA00 4E063 AA07 BC06 CA03 HA01 HA02 JA02 MA18

Claims (6)

[Claims] 1. A hollow double tube in which a core metal is inserted into an inner tube arranged with a gap formed between the outer tube and the outer tube, and a jig is inserted into the gap. A bending device for bending with a die, wherein a jig inserted into a gap formed between an outer tube and an inner tube is configured by arranging a plurality of elastic band-shaped plates in a ring shape. An apparatus for bending a hollow double pipe. 2. The jig according to claim 1, wherein the strips arranged at least on the inner and outer sides in the bending direction are formed by stacking a plurality of thin strips. The bending apparatus for a hollow double pipe described in the above. 3. The bending apparatus according to claim 1, wherein a free end of the strip is tapered. 4. The bending apparatus for a hollow double pipe according to claim 1, wherein the belt-like plate is made of spring steel. 5. A cylindrical guide member which can reciprocate along an axial direction of a jig formed by arranging a plurality of band-shaped plates in an annular shape. A bending apparatus for a hollow double tube described in Crab. 6. A structure in which a metal core inserted into the inner tube and a jig inserted into a gap formed between the outer tube and the inner tube can move independently of each other. The hollow double pipe bending apparatus according to any one of claims 1 to 5, wherein: