JP2001205352A - Mandrel for bending of bellow tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mandrel for bending of a bellow tube used for bending the bellow tube having a bellow-shaped cross section in the direction orthogonal to the axis of an inner tube. SOLUTION: In the mandrel for bending, which has plural mandrel pieces 11 and is connected in the same center axial line in a bendable and adjoined state, these mandrel pieces 11 are inserted into a bellow tube having the bellow- shaped inner periphery cross section of an inner tube in the direction orthogonal to the axis and have the outer periphery of the bellow shape roughly same as the bellow shape of the bellow tube. The outer periphery cross sectional shape in the direction orthogonal to the axis of the mandrel pieces of the mandrel is made to the bellow shape roughly same as the bellow shape of an inner periphery cross sectional shape of an inner tube in the direction orthogonal to the axis of the bellow tube, thereby the mandrel pieces 11 are inserted/fitted into the inside of the bellow tube, further in bending, the cross sectional shape of the whole working part of the inner tube having a bellow shape is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal core for bending a bellows tube. Here, the bellows pipe is a double pipe having an outer pipe and an inner pipe inserted into the outer pipe, and refers to a bellows pipe having a cross-section perpendicular to the axis of the inner circumference of the inner pipe in a bellows shape. The present invention relates to a bending core inserted into the bellows tube when the bellows tube is bent.

[0002]

2. Description of the Related Art Conventionally, when a pipe is bent, a mandrel is inserted into the inside of the pipe and bent by a pipe bender. This is to prevent a change in the cross-sectional shape of the tube caused by bending the tube since the inside of the tube is hollow.

[0003] In general, a metal core has a plurality of metal core pieces and legs for supporting the metal core pieces, but the cross-sectional shape of the metal core piece inserted into the tube and attached thereto is generally a metal core piece. In general, the cross-sectional shape of the inner circumference of the tube into which the is inserted is substantially the same. That is, it is possible to prevent the cross-sectional shape of the pipe from being changed by mounting a metal core piece having an outer cross-sectional shape substantially the same as the inner cross-sectional shape of the pipe inside the pipe.

[0004] As such a core metal, for example, there is a core metal 200 as shown in FIG. The metal core 200 is a metal core 200 for bending a pipe 250 having a circular cross section perpendicular to the axis. This core metal 200 is composed of two core metal pieces 2
01 and leg portions 202 for supporting these metal core pieces 201. The two metal core pieces 201 have a circular cross-section perpendicular to the axis and are slightly smaller than the inner diameter of the tube 250.

[0005] Bending of a pipe with a core inserted into the pipe and mounted on the pipe is generally configured so that the core can cope with bending of the pipe.
That is, when the pipe is bent by a pipe bender by connecting a plurality of metal core pieces to bendable on the same central axis to form a metal core, the metal core also bends in the bending direction corresponding to this bending process. Have to be able to. That is, the metal core pieces need to be adjacently connected so as to bend in a free direction about the same central axis.

For example, a core metal 300 shown in FIG. 7 has three core metal pieces 301 supported by a leg 302 and connected thereto. Each of the metal core pieces 301 and the legs 302 are respectively provided with spherical bearings 3.
03 are connected adjacently so as to bend in a free direction about the same central axis. In addition, it has been configured to bend in an appropriate manner than before.

[0007] In the case of a so-called elemental pipe having a single pipe, a plurality of metal core pieces whose outer cross-sectional shape is substantially the same as the inner surface shape of the pipe are connected so as to be bent on the same central axis. Conventional bending metal cores have been used.

[0008]

However, in recent years, a so-called double pipe having a double pipe structure has been used for an exhaust pipe and an exhaust manifold of an automobile. For this double tube, the conventional core metal 200 described above,
There was a problem that the 300 could not cope well. That is, the double tube has two tubes, an outer tube and an inner tube inserted into the outer tube. In this double pipe, the inner diameter of the outer pipe is larger than the outer diameter of the inner pipe so that a gap exists between the outer pipe and the inner pipe. Therefore, in a double pipe,
The outer tube and the inner tube are processed at one end of the tube, and the outer tube and the inner tube are fixed by spot welding or the like. The gap between them is made constant.

[0009] Even when such a double pipe is bent, it is necessary to ensure a space between the outer pipe and the inner pipe of the double pipe. This is because if the outer tube and the inner tube come into contact with each other as a result of the bending, the use of the double tube becomes insignificant.

However, it is necessary to devise a method for bending such a double pipe while maintaining the gap between the outer pipe and the inner pipe.
The gap between the outer tube and the inner tube cannot be maintained at a constant width simply by inserting the conventional cored bars 200 and 300 into the inside of the double tube. In this case, the sectional shape of the inner tube cannot be maintained even though the sectional shape of the inner tube can be maintained. That is, the outer tube and the inner tube come into contact with each other due to the bending process.
Therefore, it is necessary to maintain the cross-sectional shape of the outer tube.

Therefore, in the case of bending a double pipe, the gap between the outer pipe and the inner pipe is conventionally filled with sand, ceramic powder, or the like, or water is added to freeze it before bending. Was. By filling the gap between the outer tube and the inner tube with sand or the like, the width between the outer tube and the inner tube can be maintained and the cross-sectional shape of the outer tube and the inner tube can be maintained. That is, since it is necessary to secure the shape of both the outer pipe and the inner pipe in the double pipe, many steps such as filling the gap between the outer pipe and the inner pipe with sand or the like are required at the time of bending, and the cost is increased. Will also be high.

The present inventor has repeatedly studied to overcome such a problem of the double pipe, and has studied a double pipe which is easy to bend. Has been researching core metal for bending that is compatible with As a result of research, the present inventor has developed a bellows tube having a bellows-shaped cross section in the direction perpendicular to the axis of the inner tube as a double tube easily bent. FIG. 8 shows a cross-sectional shape of the bellows tube 100. The bellows tube 100 developed by the inventor is a double tube having an outer tube 101 and an inner tube 102 inserted into the outer tube 101. The cross-sectional shape of the inner tube 102 in a direction perpendicular to the axis is a bellows shape. It has a special shape. In other words, the bellows shape of the inner tube 102 can be said to be a waveform in which irregularities are repeated in the circumferential direction. The waveform of the inner tube 102 is in contact with the inner periphery of the outer tube 101 at one vertex, and the other vertex is Oriented in the direction of the central axis of the tube. The number of waves and the wave height of the inner tube 102 of the bellows tube 100 are set to appropriate values according to the size of the bellows tube 100 and the use of the bellows tube 100.

However, since the bellows tube 100 has a special shape such as the bellows shape of the inner tube 102, a core metal for bending corresponding to the bellows tube is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a core metal for bending a bellows pipe used when bending a bellows pipe having a bellows-shaped cross section in a direction perpendicular to the axis of the inner pipe.

[0015]

As a result of research, the present inventor has found that, in a bending metal core having a plurality of metal core pieces, the metal core pieces are connected adjacent to each other so as to be bent on the same central axis. The bellows are inserted into a bellows tube having an inner tube cross-section having a bellows shape in a direction perpendicular to the axis, and have an outer periphery having a bellows shape substantially the same as the bellows shape of the bellows tube. We invented a metal core for bending pipes.

In the bellows tube developed by the inventor, the inner tube has a bellows shape, and one vertex of the waveform forming the bellows shape is in contact with the inner periphery of the outer tube. Accordingly, by making the outer peripheral cross-sectional shape in the direction perpendicular to the axis of the core metal piece of the core metal for bending work substantially the same as the inner peripheral cross-sectional shape in the direction perpendicular to the axis of the inner pipe of the bellows pipe, that is, the bellows shape, Can be inserted into the bellows tube and installed inside, and at the time of bending, the cross-sectional shape of the entire bent portion of the inner tube having the bellows shape can be maintained.

As described above, the bellows shape of the inner tube can be maintained by inserting the metal core for bending according to the present invention, so that the same operation as the conventional metal core for bending the raw tube can be performed. Bending can be performed. Therefore, the gap between the outer pipe and the inner pipe required when bending a double pipe is filled with sand or the like, or a process such as putting water in for freezing, or removing the packed material in the gap, It is possible to reduce the steps such as cleaning the gap and the cost.

Further, since the bellows shape has directionality by the number of the folds, that is, the number of waves, the direction of the core is not limited to one direction, but becomes multiple directions, and the core of the present invention can be easily formed. It is possible to insert.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a core metal for bending a bellows pipe (hereinafter abbreviated as "core metal" as appropriate) of the present invention will be described below.

The metal core of the present invention is connected to bendable and adjacent on the same center axis, and in a metal core for bending having a plurality of metal cores, these metal cores are arranged in a direction perpendicular to the axis. The inner pipe has a bellows-shaped inner peripheral cross-section and is inserted into a bellows pipe, and has an outer periphery that is substantially the same as the bellows shape of the bellows pipe.

This core metal is used for bending a bellows tube, and is used by being installed in a bent portion of the bellows tube. Here, the bellows pipe is a double pipe having an outer pipe and an inner pipe as described above, and refers to a pipe whose inner peripheral cross-sectional shape in a direction perpendicular to the axis of the inner pipe has a bellows shape.

The cross section of the outer circumference of the core metal piece of the core metal of the present invention in the direction perpendicular to the axis is substantially the same as the bellows shape of the inner circumference of the inner pipe of the bellows pipe, and the core metal piece is inserted into the bellows pipe. , Inside the bent part. However, the size of the cross-sectional shape of the outer periphery of the core metal piece is the largest at the center and is substantially the same as the size of the inner pipe of the bellows tube, but the bellows shape is maintained at both ends of the core metal piece. It is preferable to reduce it. If both ends of the cored bar are the same size as the central portion, when the bellows pipe is bent, the cross-sectional shape of the tube is deformed by the end of the cored bar. Therefore, the core metal piece may be reduced to an appropriate size while gradually maintaining the bellows shape from the center to the both ends.

The thickness of the metal core piece can be set to an appropriate thickness in consideration of the size of the cross-sectional shape of the metal core piece. It becomes difficult to bend even if it is too thick or too thin. Generally, the maximum diameter of the cross-sectional shape of the metal core piece, that is, approximately 0.4 of the diameter of a circle formed by connecting the outer vertices of the waves constituting the bellows shape.
About 0.8 times.

The material of the metal core piece is not particularly limited, but a material having a breaking strength is preferable in consideration of application of pressure. For example, it is preferable to use tool steel. The bellows-shaped surface of the metal core piece is preferably smooth. This is because the smoother the core metal piece can be easily inserted or pulled out.

The plurality of metal core pieces are connected adjacently so as to be bendable on the same central axis. The number of core metal pieces is not particularly limited as long as it is plural. An appropriate number can be set according to the degree of bending. It can be two, three or more.

The metal core pieces can be connected at appropriate intervals. Generally, it is sufficient that the diameter is approximately 0.1 times the maximum diameter of the cross-sectional shape of the metal core piece, that is, the diameter of a circle formed by connecting the outer vertexes of the waves constituting the bellows shape.

This connection may be made by an appropriate method so that the metal core pieces can bend in any direction around the same central axis. For example, the core metal pieces can be connected on the same central axis using the above-described spherical bearing as a connecting member. In this case, the metal core pieces can not only bend around the same central axis but also rotate in the circumferential direction.
In this case, since the core metal piece rotates freely also in the circumferential direction, the phase of the core metal piece as viewed from the axial direction of the bellows shape does not need to match from the beginning, and the core metal piece is inserted into the bellows tube. In each case, the bellows-shaped phase of the cored bar can be inserted in accordance with the bellows-shaped phase of the bellows tube.

Alternatively, the metal core pieces can be connected on the same central axis by using an elastic body such as rubber as a connecting member for connecting the metal core pieces.

It is preferable that the metal core pieces are not rotated in the circumferential direction, and the metal core pieces are connected adjacently so that the phases of the bellows shapes of the metal core pieces when viewed from the axial direction match.
If the core metal is configured so that the phases of the bellows shapes of the core metal pieces match, if the core metal piece located at the foremost end is inserted into the bellows tube, the later metal core piece can be easily bellowed. It can be inserted into a tube. For example, by using elastic rubber as a connecting member, the core metal pieces can be connected such that they are bent around the same central axis, but do not rotate in the circumferential direction, so that the phases of the bellows shapes match. .
When a connecting member that can also rotate in the circumferential direction is used, such as a mirror bearing, a plurality of core metal pieces are connected by a stretchable wire parallel to the same central axis, thereby forming a bellows shape of the metal core pieces. They can be connected adjacently so that they are in phase.

Generally, the plurality of metal core pieces are foldably connected to the ends of the legs of the metal core. The legs of the metal core support a plurality of metal core pieces, and facilitate insertion of the metal core pieces into the bent portion and interior decoration. The legs of the mandrel can have a size and shape that can be inserted inside the bellows tube. Therefore, the cross-sectional shape of the legs of the metal core at right angles to the axis does not need to be particularly bellows-shaped. The shape may be smaller than the cross-sectional shape of the inner pipe of the bellows pipe. The reason is that the legs of the cored bar need not actively hold the cross-sectional shape of the inner tube of the bellows tube from inside, as long as the cored bar can be pushed into the bent portion of the bellows tube.

The connection between the core metal piece and the leg portion may be performed by an appropriate method so as to be bendable. For example, the leg and the core metal piece can be connected using a spherical bearing and an elastic body such as rubber as a connecting member.

However, the outer periphery of the leg portion of the cored bar may be formed in a bellows shape substantially the same as the bellows shape of the bellows tube, similarly to the cored bar piece. When the legs of the cored bar have the bellows shape, the legs can also hold the cross-sectional shape of the inner tube of the bellows tube from the inside. In this case, the legs play the same role as the metal core piece, and also play the role of supporting the metal core piece. In other words, in this case, the legs are at the same time core pieces.

In this case, that is, when the leg also has a bellows shape and also serves as a core metal piece, the phase of the bellows shape of the leg coincides with the phase of the bellows shape of the metal core piece when viewed from the axial direction. It is preferable that the leg and the metal core piece are connected as described above. If the core metal piece to be inserted first is inserted into the bellows tube if connected in this way, the leg portion of the core metal can be easily inserted into the bellows tube. In this case, the connection between the leg and the core piece can be performed in the same manner as the connection of the core piece.

After inserting the cored bar piece into the bent portion of the bellows tube and installing the inside, the bellows tube can be bent by applying pressure to the bellows tube using an appropriate device such as a pipe bender. After the bending process is completed, the core metal piece may be extracted from the bellows tube using the leg.

[0035]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a core metal according to the present invention.

(Embodiment 1) FIGS. 1 and 2 show a cored bar of Embodiment 1. FIG. FIG. 3 shows a cross-sectional shape in a direction perpendicular to the axis of the bellows tube in which the core of the present embodiment is inserted and housed. In the core metal 10 of the present embodiment, three core metal pieces 11 are connected to the leg portion 12 so as to be bent on the same central axis. These metal core pieces 11 are inserted into a bellows pipe 20 in which the inner peripheral cross-sectional shape of the inner pipe 22 in the direction perpendicular to the axis is a bellows shape, and have an outer periphery that is substantially the same as the bellows shape of the bellows pipe 20. ing.

The bellows tube 20 used in the following embodiment is a double tube having an outer tube 21 and an inner tube 22 inserted into the outer tube 21. Has a special shape called a bellows shape. In other words, the bellows shape of the inner tube 22 can be said to be a waveform in which irregularities are repeated in the circumferential direction. The waveform of the inner tube 22 is in contact with the inner peripheral surface of the outer tube 21 at one vertex and the vertex on the other side is a tube. In the direction of the central axis.

The core metal piece 11 of the core metal 10 of this embodiment has the largest cross-sectional shape in the direction perpendicular to the axis at the center thereof, and is substantially the same as the size of the bellows shape on the inner periphery of the bellows tube 20. Then, while maintaining the bellows shape, the size is gradually reduced from the center to both ends. This is for preventing the change of the cross-sectional shape of the bellows pipe 20 when the bellows pipe 20 is bent and provided inside the bent portion of the bellows pipe 20. The core metal piece 11 is manufactured using tool steel. The core metal piece 11 is subjected to a surface treatment in order to reduce the sliding resistance friction and the affinity with the product tube.

The three metal core pieces 11 are connected via a spherical bearing 13a. Therefore, the metal core piece 11 of the present embodiment can be bent about the same central axis, and can also be rotated in the circumferential direction. Also, the leg portion 12 has a bellows outer periphery similarly to the metal core piece 11, and the leg portion 12 and the metal core piece 11 are connected via a spherical bearing 13a. The size of the outer periphery of the leg portion 12 is basically the same as the bellows shape of the inner periphery of the bellows tube 20, but the end of the leg portion 12 connected to the core metal piece 11 also has a bellows shape. The size is reduced while maintaining. The legs 12 are made using tool steel. The leg 12 is also subjected to the same surface treatment as the surface treatment applied to the metal core piece 11.

In this embodiment, the metal core pieces 11 bend around the same central axis and also rotate in the circumferential direction. Therefore, the respective core metal pieces 10 and the leg portions 12 are fitted to the bellows
Can be inserted.

After this, the core metal piece 11 is inserted up to the bent portion of the bellows tube 20, and after the interior, the outer tube 21 is subjected to bending by applying pressure to the outer tube 21 using a pipe bender or the like.

(Embodiment 2) FIGS. 4 and 5 show a cored bar of Embodiment 2. FIG. Note that the same reference numerals as those used in the first embodiment are used for the same elements in the drawing.
The cross-sectional shape in the direction perpendicular to the axis of the bellows tube in which the core of the present embodiment is inserted and which is installed is the same as that in FIG. Therefore, FIG. 3 is also used in this embodiment.

The core 10 of the second embodiment has the same structure as the first embodiment.
The individual metal core pieces 11 are connected to the leg portions 12 so as to be bent on the same central axis. These metal core pieces 11 are inserted into a bellows pipe 20 in which the inner peripheral cross-sectional shape of the inner pipe 22 in the direction perpendicular to the axis is a bellows shape, and have an outer periphery that is substantially the same as the bellows shape of the bellows pipe 20. ing.

The core metal piece 11 of the core metal 10 of the present embodiment has the largest cross-sectional shape in the direction perpendicular to the axis at the central portion thereof, and has substantially the same size as the bellows shape on the inner periphery of the bellows tube 20. Then, while maintaining the bellows shape, the size is gradually reduced from the center to both ends. This is for preventing the change in the cross-sectional shape of the bellows tube 20 when the bellows tube 20 is bent and is provided inside the bent portion of the bellows tube 20. In this embodiment, the core metal piece 11 is also used.
Are manufactured using tool steel.

The core metal 10 of this embodiment has a core metal piece 11 connected via a rubber elastic body 13b. The metal core pieces 11 can be bent about the same central axis, but are not configured to rotate in the circumferential direction. The outer periphery of the leg 12 also has a bellows shape, like the metal core piece 11.
The core metal piece 11 is also connected via a rubber elastic body 13b. The size of the outer circumference of the leg 12 is basically the same as the bellows shape of the inner circumference of the bellows tube, but the end of the leg 12 connected to the core metal piece 11 also has the bellows shape. The size is reduced while maintaining it. The legs 12 are also made using tool steel.

In this embodiment, since the three metal core pieces 11 and the legs 12 do not rotate in the circumferential direction, the three metal core pieces 1
The bellows shapes on the outer circumference of the leg 1 and the leg 12 are connected so that the phases match when viewed from the axial direction.

Therefore, if the core metal piece 11 located at the foremost end is inserted into the bellows tube 20, the remaining metal core pieces 11 and the legs 12 are particularly adjusted in phase with the bellows shape of the bellows tube 20. It can be inserted into the bellows tube 20 without it.

After this, the core metal piece 11 is inserted up to the bent portion of the bellows tube 20, and after the interior, the outer tube 21 is subjected to bending by applying pressure to the outer tube 21 using a pipe bender or the like.

(Embodiment 3) The core of the third embodiment is the same as the core of the first embodiment. However, the core metal piece is configured not to rotate in the circumferential direction by the coil spring so that the phases of the core metal piece and the leg portions viewed from the axial direction of the bellows shape match. That is, holes are formed in the second and third metal core pieces counted from the tip so that the coil spring can pass therethrough, and the coil spring inserts these holes between the metal core piece at the foremost end and the leg. It is stretched between the core metal piece at the foremost end and the leg so as to be parallel to the same central axis. By matching the phases of the bellows shape of the core metal piece and the leg with the core metal piece and the leg with a single coil spring parallel to the same central axis, the core metal piece and the leg are connected. By suppressing rotation in the circumferential direction, it is possible to maintain the same phase of the bellows shape.

Therefore, if the core metal piece located at the foremost end is inserted into the bellows pipe, the remaining metal core pieces and the legs are not particularly required to adjust the bellows-shaped phase to the bellows-shaped phase of the bellows pipe. Can be inserted.

After this, the core metal piece is inserted up to the bent portion of the bellows pipe, and after the interior, the pipe can be bent by applying pressure to the outer pipe using a pipe bender or the like.

[0052]

The core metal according to the present invention can be bent by the same operation as a conventional core metal for bending a raw tube. Therefore, filling the gap between the outer pipe and the inner pipe necessary when bending a double pipe with sand or the like, or adding water to freeze it, or filling the gap after bending. , And steps for cleaning the gap, cost, and the like can be reduced. Further, the bending operation can be performed by the conventional operation, and the above-described steps can be reduced, so that the working environment can be improved.

Further, since the bellows shape has directionality by the number of the folds, that is, the number of waves, the direction of the core is not limited to one direction, but becomes multiple directions, and the core of the present invention can be easily formed. It is possible to insert.

When the core metal of the present invention is manufactured so that the phases of the bellows shapes on the outer periphery coincide with each other, the core metal is first inserted into the bellows tube so that the subsequent core metal is also attached to the bellows tube. It can be easily inserted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a central portion of a metal core piece of a metal core for bending a bellows pipe according to a first embodiment.

FIG. 2 is a side view of a core metal for bending the bellows pipe of Example 1;

FIG. 3 is a sectional view of a bellows tube according to the first and second embodiments.

FIG. 4 is a cross-sectional view of a central portion of a metal core piece of a metal core for bending a bellows pipe according to a second embodiment.

FIG. 5 is a side view of a bending metal core of the bellows tube of Example 2 viewed from a side surface.

FIG. 6 is a side view of a conventional metal core piece.

FIG. 7 is a cross-sectional view of a conventional cored bar using a spherical bearing.

FIG. 8 is a cross-sectional view of the bellows tube in a direction perpendicular to the axis.

[Explanation of symbols]

 10: Core metal for bending of bellows pipe 11: Core metal piece 12: Leg 13a: Spherical bearing 13b: Rubber elastic body 20: Bellows pipe 21: Outer pipe of bellows pipe 22: Inner pipe of bellows pipe 100: Bellows pipe 101: Outer pipe of bellows pipe 102: Inner pipe of bellows pipe 200: Core 201: Core piece 202: Leg 250: Pipe 300: Core 301: Core piece 302: Leg 303: Spherical bearing

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Kato 1 No. 1 Tenno, Takaokashinmachi, Toyota-shi, Aichi F-term in Aisin Takaoka Co., Ltd. 4E063 AA07 HA03

Claims (3)

[Claims] 1. A bending metal core having a plurality of metal core pieces, which are connected adjacently and bendably on the same center axis, wherein the metal core pieces have an inner circumference of an inner pipe in a direction perpendicular to the axis. A core metal for bending a bellows tube, which is inserted into a bellows tube having a bellows cross section and has an outer periphery having a bellows shape substantially the same as the bellows shape of the bellows tube. 2. The bellows pipe bending process according to claim 1, wherein the plurality of core metal pieces are connected adjacently so that a phase of the bellows shape of the outer periphery matches when viewed from an axial direction. Core metal. 3. A plurality of core metal pieces are connected adjacently by a stretchable wire parallel to the same central axis so that the phases of the bellows shapes match.
A core metal for bending the bellows tube described in the above.