JPH08276222A - Method for bending hollow double pipe - Google Patents

Abstract

PURPOSE: To provide a bending method of a double pipe by which energy consumption is suppressed to the absolute min., cycle time is shortened and a charged material is surely discharged. CONSTITUTION: This method is composed of a process in which the charging material consisting of plural bar-shaped rectilinear wires 6 is charged into the space of the hollow double pipe 4 along the longitudinal direction of the space 9, process in which the hollow double pipe 4 is bent and process in which the rectilinear wires 6 are pulled out of the bended hollow double pipe 4. Since the rectilinear wires 6 are used as the charging material, heating and cooling processes are unnecessitated as compared to the case that the charging material is water (ice), large energy consumption for heating and cooling is omitted and also the cycle time is shortened. As compared to the case that the charging material is sand or a steel ball, the generation and scattering of dust is not brought about. Further, as compared to that the charging material is wax, heating at the time of charging and discharging the charging material is unnecessitated, so energy consumption is reduced as much and the cycle time is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a hollow double pipe used for an automobile exhaust pipe, a heat insulating pipe, a plant pipe and the like.

[0002]

2. Description of the Related Art A hollow double tube has an excellent heat insulating effect due to the presence of an air layer in a space formed between an outer tube and an inner tube, and has a heat insulating property for a fluid in an automobile, a plant or the like. It is used for securing parts. For example, it can be used in an exhaust pipe of an automobile to guide exhaust gas to a catalyst in a high temperature state, promote a chemical reaction in the catalyst, and reduce harmful components in the exhaust gas.

Incidentally, the hollow double pipe is sometimes bent and used in order to avoid interference with other members in terms of arrangement. When bending a hollow double pipe, in order to bend the inner pipe with the same curvature as the outer pipe, insert a cored bar (mandrel) into the inner pipe or insert a space between the inner pipe and the outer pipe. The filling material is filled. As a filler,
Currently, water (ice), sand, steel balls, wax, etc. are used.

[0004]

However, the above-mentioned conventional technique using water (ice), sand, steel balls, and wax as the filler has the following problems.
That is, when the filling material is water (ice), after filling the pipe with water, it is made into ice by a refrigerator and bent in that state, and after the bending process, it is heated and returned to water and discharged. There is. Therefore, a lot of energy is consumed for heating and freezing, and a lot of time is required to complete the bending work, that is, the cycle time becomes long.
Freon is often used in the refrigerator, but this is not desirable because it deteriorates the global environment.

When the filling material is sand, dust and noise are generated when the sand is filled and discharged. In addition, for example, when oil adheres to the portion where the inner pipe and the outer pipe are joined, sand may adhere to the oil and remain in the pipe. Further, the sand may scatter and damage the bender machine or the like. When the filler is a steel ball, it has the same problems as in the case of sand described above.

When the filler is wax, the filler needs to be heated to a temperature equal to or higher than the melting point during filling and discharging, which requires a large amount of energy and a long cycle time.
Furthermore, it is necessary to check the physical properties of the wax frequently in order to prevent the hardness and deterioration of the wax, which requires a lot of labor to manage the physical properties.

The present invention has been made in view of the above circumstances, and it is a method for bending a hollow double pipe capable of minimizing energy consumption, shortening a cycle time, and reliably discharging a filler. The purpose is to provide.

[0008]

According to the first aspect of the present invention,
Filling the void in the hollow double pipe in which the inner pipe is inserted with a predetermined void in the outer pipe, filling a filler made of a plurality of rod-shaped straight wires along the longitudinal direction of the void, and the filling It is characterized by comprising a step of bending the hollow double tube by applying bending stress to the hollow double tube filled with the material, and a step of taking out the filling material from the bent hollow double tube.

According to a second aspect of the present invention, the inner tube is filled with a filler made of a coiled wire spirally wound in the void in the hollow double tube in which the inner tube is inserted with a predetermined void in the outer tube. And a step of bending the hollow double tube by applying bending stress to the hollow double tube filled with the filling material, and the filling material from the bent hollow double tube. And a step of taking out.

According to a third aspect of the present invention, a filling material composed of a plurality of straight wires and a plurality of coiled wires is provided in the void in the hollow double tube in which the inner tube is inserted with a predetermined void in the outer tube. Filling the linear wire along the longitudinal direction of the void, and filling the coiled wire so as to be wound around the inner tube or the linear wire, and the hollow double tube filled with the filler. The method is characterized by comprising a step of bending the hollow double tube by applying a bending stress and a step of taking out the filler from the bent hollow double tube.

[0011]

In the method of the present invention, a straight wire or a coiled wire is used as the filling material, and heating and cooling steps are unnecessary as compared with the case where the filling material is water (ice). Also, dust is not generated or scattered as compared with the case where the filler is sand or steel balls. Further, heating at the time of filling and discharging is unnecessary as compared with the case where the filler is wax.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a pair of movable molds 1 and 2 that can be opened and closed is opened, and a round bar 3 is inserted therein. The outer diameter of the round bar 3 is set to be slightly smaller than the inner diameter of the inner tube 5 of the hollow double tube 4 described later, and the round bar 3 is set inside the inner tube 5 in a step (FIG. 3) described later. The hollow double tube 4 is inserted so that the movement of the hollow double tube 4 is not suppressed. Next, a plurality of rod-shaped linear wires (filler) 6 made of metal such as steel and copper are housed around the round rod 3.

Then, as shown in FIG. 2, the first and second round bars 3 are positioned so that the round bar 3 is located at the center of the cylindrical space 7 formed by the first and second movable molds 1 and 2. The movable molds 1 and 2 are closed.

On the other hand, a hollow double tube 4 as shown in FIG. 4, for example, is prepared in advance. This hollow double tube 4
The outer tube 8 and the inner tube 5 that is inserted through the outer tube 8 with a predetermined gap 9 therebetween are generally configured. On one end side of the inner pipe 5, a diameter-expanded portion 10 whose diameter dimension increases toward the end.
The outer diameter of the end portion of the expanded diameter portion 10 is substantially the same as the inner diameter of the outer tube 8 (a dimension that can be inserted). The expanded diameter portion 10 and the outer pipe 8 are joined by spot welding, for example, thereby forming the hollow double pipe 4 in which the outer pipe 8 and the inner pipe 5 are fixed. Further, the gap 9 is closed on the joint side by the joining of the expanded diameter portion 10 and the outer pipe 8 while being opened on the other end side (hereinafter, for convenience, the opening 9a of the gap 9 will be referred to as an opening 9a). That is).

Following the operation shown in FIG. 2, as shown in FIG. 3, the center of the hollow double tube 4 is aligned with the center of the round bar 3 in the first and second movable molds 1 and 2, and the space is formed. The opening 9a of 9
The hollow double tube 4 is arranged so as to face the ends of the linear wires 6 in the first and second movable molds 1 and 2, and the hollow double tube 4 is placed in the space portion 7 on the straight wire 6 side. Pushing, thereby filling the linear wire 6 along the longitudinal direction of the void 9 as shown in FIGS. 5 and 6.

Next, as shown in FIG. 7, a cored bar (mandrel) 11 is inserted into the inner tube 5 of the hollow double tube 4 in which the void 9 is filled with the linear wire 6 and the bender machine 12 is used. Bend. The bender machine 12 includes a wiper die 12 for placing and guiding the hollow double tube 4, a pressure die 14 for pressing the hollow double tube 4 against the wiper die 13, and a rotatably supported and tightened by the wiper die 13. Die 15
A rotary bending die 1 that applies bending stress to the hollow double tube 4 together with
It is composed of 6 and 6. And wiper die 1
Bending stress is applied to the hollow double tube 4 by rotating the rotary bending die 16 while pressing the hollow double tube 4 with 3 and the clamping die 15. Due to this bending stress, the outer pipe 8 bends to a desired curvature, and the bending stress also acts on the inner pipe 5 through the plurality of linear wires 6 with which the voids 9 are filled, and the inner pipe 5 bends equally. Will be done.

Next, the straight wire 6 in the bent hollow double tube 4 is pulled out to obtain the bent hollow double tube 4 not containing the straight wire 6. In the bending process described above, a large compressive stress is applied to the inner side portion M _I of the bend of the hollow double tube 4 and a large tensile stress is applied to the outer side portion M _{O of the} bend, while A relatively small stress is applied to the portion M _T. At the time of pulling out the linear wire 6, the linear wire 6 is pulled out in order from a portion having a small stress, so that the pulling operation can be easily performed. Further, at the time of extraction, a liquid lubricant such as oil may be added to the void 9 to reduce the extraction resistance and improve workability.

Subsequently, the drawn and bent linear wire 6 is formed into a linear shape and reused in the next bending process so that the consumption of the linear wire 6 is minimized.

In the method for bending the hollow double tube 4 configured as described above, the hollow double tube bent at a desired curvature is used without using water (ice), sand, steel balls or wax as a filler. Get the tube 4. Since water (ice) is not used as the filling material, the heating and cooling steps are not required, and it is possible to omit the consumption of much energy for heating and cooling and to shorten the cycle time. In addition, it is possible to maintain a good global environment without the use of CFC required for refrigerators.

Even if oil is present in the pipe, it is possible to reliably discharge the linear wire 6 by applying a tensile force to the linear wire 6, and the oil does not remain inside. In this respect, there is no fear of remaining in the pipe that may occur when using sand or steel balls as the filler. In addition, the generation of dust that could occur when the filler is sand is not caused. Further, the bender machine 12 is not damaged by the scattering that may occur when the filler is sand or steel balls.

When the filler is wax, it needs to be heated above the melting point at the time of filling and discharging, which requires a lot of energy and prolongs the cycle time. On the other hand, heating is unnecessary. Yes, the energy consumption is low and the cycle time is short. Further, since the physical property management of the wax is not required, the physical property management labor is omitted as compared with the case where the filler is wax.

In the above embodiment, the filling material (straight wire 6)
The example is made of a metal such as steel or copper, but instead of this, a resin-made linear wire 6, a vinyl-coated metal linear wire 6 or a solder-made linear wire 6 may be used. Good. By using the linear wire 6 made of resin, the linear metal wire 6 coated with vinyl, or the linear wire 6 made of solder in this manner, the pulling resistance is reduced and the pulling workability is improved. Can be made. In addition, a predetermined number of metal linear wires 6, the resin linear wires 6, the vinyl linear metal-coated wires 6 or the solder linear wires 6 are used as fillers. It may be formed to improve the drawing workability.

In the above embodiment, the case where the filling material is the linear wire 6 is taken as an example.
Alternatively, a coiled wire 17 wound in a spiral shape may be used as shown in FIG. The coiled wire 17 is formed by bundling several metal wires and winding them in a spiral shape. The coiled wire 17 is wound around the inner tube 5 so as to be filled in the space 9 to obtain the hollow double tube 4 filled with the coiled wire 17 as shown in FIGS. 9 and 10.

Next, as in the case shown in FIG. 7, the core metal 11 is inserted into the inner tube 5 of the hollow double tube 4 having the void 9 filled with the coiled wire 17, and the bender machine 12 is used. And bend it. Also in this case, as in the case where the straight wire 6 is filled, the bending stress of the bender machine 12 causes the outer tube 8 to bend to a desired curvature, and the bending stress causes a void 9
The inner pipe 5 also acts on the inner pipe 5 through the coiled wire 17 filled in the inner pipe 5, and the inner pipe 5 is bent equally.

In the method for bending a hollow double tube constructed as described above, the hollow double tube bent at a desired curvature without using water (ice), sand, steel balls or wax as a filler. 4 can be obtained, and energy saving and shortening of cycle time can be achieved in the same manner as in the above embodiment in which the linear wire 6 is filled.

A plurality of linear wires 6 and a plurality of coiled wires 17 are used as the filling material, and the linear wires 6 and the coiled wires 17 are formed as shown in FIG. 11, FIG. 12 or FIG. The voids 9 may be filled. The hollow double tube 4 shown in FIG. 11 has an inner tube 5 with a coiled wire 1
7 is wound and a plurality of linear wires 6 are filled on the outer peripheral side thereof. In FIG. 12, a plurality of linear wires 6 are arranged on the outer circumference of the inner pipe 5, and a coiled wire 17 is wound and filled on the outer circumference thereof. In FIG. 13, a plurality of linear wires 6 are arranged on the outer circumference of the inner pipe 5 and
The coiled wire 17 is eccentrically arranged with respect to the center of the above, and is arranged and filled so as to cut into the plurality of linear wires 6. With such a configuration, it is possible to improve the non-uniform state of the stress generated in the bending process, and to achieve better bending forming.

[0027]

In the method of the present invention, a straight wire or a coiled wire is used as the filling material, and heating and cooling steps are unnecessary as compared with the case where the filling material is water (ice). The consumption of much energy for heating and cooling can be omitted, and the cycle time can be shortened. Also, dust is not generated or scattered as compared with the case where the filler is sand or steel balls. Further, compared to the case where the filler is wax, heating at the time of filling and discharging is unnecessary, so energy consumption is reduced accordingly.
And the cycle time becomes short. Further, since the physical property management of the wax is not required, the physical property management labor is omitted as compared with the case where the filler is wax.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which first and second movable dies used in a method for bending a hollow double tube according to an embodiment of the present invention are opened.

FIG. 2 is a perspective view showing a state in which a linear wire is inserted into a space formed in the first and second movable molds.

FIG. 3 is a perspective view showing a step of filling a straight wire into the hollow double tube.

FIG. 4 is a perspective view schematically showing the hollow double tube.

FIG. 5 is a plan view showing a hollow double tube filled with a straight wire.

6 is a cross-sectional view of a hollow double tube corresponding to FIG.

FIG. 7 is a cross-sectional view schematically showing a bending state of a hollow double tube using a bender machine.

FIG. 8 is a perspective view showing a bent hollow double tube.

FIG. 9 is a plan view showing a hollow double tube filled with a coiled wire.

10 is a cross-sectional view of the hollow double tube corresponding to FIG.

FIG. 11 is a plan view showing a hollow double tube in which a linear wire is filled on the outer peripheral side of a coiled wire.

FIG. 12 is a plan view showing a hollow double tube in which a coiled wire is wound and filled around a straight wire.

FIG. 13 is a plan view showing a hollow double tube filled with a coiled wire so as to cut into a straight wire.

[Explanation of symbols]

 4 Hollow double tube 5 Inner tube 6 Straight wire 8 Outer tube 9 Void

Claims (3)

[Claims] 1. A filling material made of a plurality of rod-shaped linear wires is filled along the longitudinal direction of the hollow double tube in which the inner tube is inserted with a predetermined space left inside the outer tube. A step of bending the hollow double tube by applying a bending stress to the hollow double tube filled with the filler, and a step of taking out the filler from the bent hollow double tube. Characteristic hollow double tube bending method. 2. A filling material made of a coiled wire spirally wound around an inner pipe is wound around the void in a hollow double pipe in which the inner pipe is inserted with a predetermined space left inside the outer pipe. It comprises a step of filling, a step of bending the hollow double tube by applying a bending stress to the hollow double tube filled with the filler, and a step of taking out the filler from the bent hollow double tube. A method for bending a hollow double tube, which is characterized in that 3. A straight wire of a filler made up of a plurality of straight wires and a plurality of coiled wires is inserted into the void in the hollow double pipe in which the inner pipe is inserted with a predetermined void in the outer pipe. Along with filling along the longitudinal direction of the void, a step of filling the coiled wire so as to be wound around an inner tube or a straight wire, and applying bending stress to the hollow double tube filled with the filling material A method for bending a hollow double tube, comprising a step of bending the hollow double tube and a step of taking out the filler from the bent hollow double tube.