JP2002113524A - Core for working metal tube and method for working metal tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart a pressure required for a whole tube inner face of a working region in a process of working, to prevent a wrinkle and a shape defect in bending/flattening a tube, to commonly use for manufacturing worked products having various cross sectional sizes and to quickly take in/out a core. SOLUTION: The core 10 is provided with a cylindrical or bag like hollow body 1 made of an elastic material and a fluid supply means to supply/discharge a fluid for bulging a peripheral length of the hollow body into/from its inside space. The core is arranged in the tube of plastic deforming section of a tube stock of a metal tube, a fluid is supplied in the inside space with a pressure not causing plastic deformation of the metal tube, the hollow body made of an elastic material is bulged, its outer peripheral face is brought into tight contact with an inner peripheral face of the metal tube, thereafter, a prescribed working is conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core to be inserted into a metal tube and a metal tube using the core during bending of a metal tube using a molding die or flattening from a round section to a rectangular section. The method of processing.

[0002]

2. Description of the Related Art In bending or flattening of a metal tube (hereinafter simply referred to as a tube) using a molding die, a core is formed inside a tube in order to make a cross section of a processed portion of the tube into a desired shape. It is often performed to insert and process the tools mentioned.

[0003] First, the bending will be described. FIG. 7 shows a typical example of a defective phenomenon in bending of a pipe,
FIG. 7A shows wrinkles 50 formed by buckling of the material due to an axial compressive force acting on the inside of the bend. FIG. 7 (b)
Due to the axial tensile force acting on the outside of the bend, a contour shape to be machined as shown by a broken line is not obtained, and the cross section is flattened. These failure phenomena are represented by R
The smaller the value of / D (R: bending radius of the pipe shaft, D: the outer diameter of the pipe) and the smaller the value of t / D (t: the wall thickness of the pipe), the more likely it is to occur. Has been taken.
Hereinafter, two typical bending methods will be described as examples.

A first bending method is a draw bending method shown in FIG. FIG. 8A is a plan view showing a state immediately before the pipe 60 is bent, and FIG.
2 is a front view as viewed from the front end (left end in the figure).

The circumference of the pipe 60 is clamped non-slidably in the axial direction by a semi-circular groove straight portion 61 a provided on the bending die 61 and a semi-circular groove 64 a of the clamp die 64 pressurized by the hydraulic cylinder 65. Is done. Further, the semicircular cross-sectional groove 67a of the wiper die 67 and the hydraulic cylinder 69
Semi-circular cross-sectional groove 68a of the pressure die 68 pressurized by
Slidably in the axial direction. These semi-circular grooves 6
The radius of curvature of 1a, 64a, 67a, 68a is substantially the same as the outer radius of tube 60.

A plug 71 connected to a rod 72 whose base end is gripped by a device (not shown) is inserted into the tube 60 as a core. The plug 71 is composed of a body 71a having an outer diameter substantially equal to the inner diameter of the pipe and a beaded structure 71b having a flexibility, and the plug 7 is positioned so that the tip of the body 71a is located at the bending start point P.
1 is set.

FIG. 8C shows that the rotary table 66 on which the bending die 61 and the clamp die 64 are mounted is rotated by a drive device (not shown) by a predetermined angle around the bending die shaft 62 and at the same time, the pressure die 6 is rotated.
8 shows a state in which the slide table 70 on which the tube 8 is mounted is linearly moved in the moving direction of the tube 60.

By rotating the bending die 61 fixed to the bending die shaft 62 with the key 63, the pipe 60 is bent.
The pipe 60 is wound around a semi-circular cross-sectional groove 61b provided along the periphery of the pipe 60, and a bending process of a predetermined radius R is performed. Accordingly, the rear end side (right side in the figure) of the pipe 60 advances. The reason why the pressure die 68 is moved in the traveling direction of the pipe 60 is to reduce the tensile force acting on the outside of the pipe 60 in bending and to suppress the decrease in wall thickness as much as possible.

In the draw bend method, an area extending slightly from the bending start point P to the rear is a wrinkle danger area. The wrinkle 50 (FIG. 7) (A)
Reference). Gem structure part 7 of plug 71
1b bends according to the bent shape of the tube 60, and prevents the flattened shape defect 51 (see FIG. 7B) in the cross section of the bent portion.

The second bending method is a press bending method shown in FIG. FIG. 9A is a side view illustrating a state immediately before bending the pipe 80, and FIG. 9B is a front view illustrating the state immediately before bending as viewed from the pipe axis direction.

The inside of the tube 80 is densely filled with granular material 81 such as sand as a core, and lids 80a are attached to both ends of the tube by welding or screwing. Granular material 8
The tube 80 filled with 1 is placed in a semicircular cross-sectional groove 83a provided in a pair of right and left dies 83 with both ends supported. Then, the lower surface is formed into a bent surface having a predetermined radius R, and the bending die 82 attached to a pressing device (not shown) is lowered from above, and the semicircular cross-sectional groove 82 a provided on the bending surface of the bending die 82 is formed. The tube 80 is brought into contact with the bending start point P. The radius of curvature of these semi-circular grooves 83a, 82a is substantially the same as the outer radius of the tube 80. Shaft 83b of each die 83
Is rotatably mounted in an arc-shaped groove 84 a provided in the gantry 84.

FIG. 9C shows that the bending die 82 is pressed by a pressing device (not shown), and the right and left dies 83 rotate to rotate the pipe 8.
0 indicates a state in which bending at a predetermined angle has been performed. At this time,
The granular material 81 follows the bending of the tube 80 and prevents the occurrence of wrinkles 50 and shape defects 51 (see FIG. 7).

Next, the flattening of the pipe will be described. 10A and 10B show an example of a deformed pipe 90 in which a round pipe is partially flattened. FIG. 10A is a perspective view, FIG. 10B is a plan view, and FIG. 10C is a side view.

The modified tube 90 has a rectangular section having a width w, a height h, and a length L ₁ at both ends 90 a while maintaining a round tube having an outer diameter D, and a length (L) therebetween. there are ₂ -L ₁₎ / ₂ of the shape gradually changing portion 90b. When the circumferential length of each section in the longitudinal direction of the deformed pipe 90 is the same, it is manufactured by a flattening method as shown in FIG.

FIG. 11A shows a state in which the tube 100 in which the cores 103 and 104 are inserted is set on the lower die 101, and the upper die 102 attached to a pressurizing device (not shown) is lowered, and It is a longitudinal cross-sectional view of the state which made contact. The cores 103 and 104 are rigid bodies such as metal. FIG.
FIG. 12B is a sectional view taken along the line II-II of FIG.

The large diameter portion 103a of the core 103 and the core 104
The outer diameter of the large diameter portion 104 a is substantially the same as the inner diameter of the tube 100. Height h ₁ of small diameter portion 103b of core 103
Is a value obtained by subtracting twice the thickness of the pipe 100 from the height h of the central portion 90c of the deformed pipe 90. Width w ₁ of the small-diameter portion 103b of the core 103 is as large as possible within a range that can be inserted into the unprocessed tube 100. Cores 103 and 104
Are detachably connected so as not to fall out of the tube being flattened.

FIG. 11C is a longitudinal sectional view showing a state in which the upper mold 102 is pressed down to complete flattening.
FIG. 12D is a sectional view taken along a line II-II in FIG. Upper die 10
2 is lifted, the cores 103 and 104 are disconnected, and the cores 103 and 104 are removed from the deformed tube 90.

[0018]

However, the plug 71 in the draw bend method shown in FIG. 8 has two problems. The first problem is the friction between the plug 71 and the inner surface of the tube. The friction causes scratches on the inner surface of the tube, and in a severe case, it becomes a scorch due to seizure, and the bent tube 60a after processing has to be discarded. Further, the frictional force increases the tensile force on the outside of the bending of the pipe, resulting in an excessive decrease in wall thickness and breakage. As a countermeasure, a method of providing a flow path for supplying a lubricating liquid inside the rod 72 and supplying the lubricating liquid to the outer surface of the plug 71 has been adopted. It takes time to wash and remove the lubricating liquid from the inner surface of the bending tube 60a later. The second problem is
It is necessary to prepare a plug 71 for each inner diameter of the tube 60, which is costly.

The granular material 81 in the press bending method shown in FIG. 9 has two problems. The first problem is
In this case, it is time-consuming to fill the granular material 81 and attach the lid 80a so that the granular material 81 does not protrude from the end of the tube during the bending process, and remove the lid from the bent tube 80b after the process.
The second problem is that in order to prevent the wrinkles 50 and the shape defects 51, it is necessary to densely fill the granular material 81, and it takes time to perform the filling operation and take out the granular material from the bent tube 80b after processing. It is.

Further, the cores 103 and 104 in the flattening shown in FIG. 11 have five problems. The first problem is that the vertical / horizontal dimension ratio h /
The dimensional accuracy is poor when w is small. That is, h /
When w is small, a large dent 110 as shown in FIG.
A flat defect 111 shown in FIG. According to the inventor's experience, under the condition of h / w ≦ 0.3, it is difficult to finish the product surface flat even if the pressing force of the upper die 102 at the bottom dead center of the flat processing is increased. .

The second problem, as shown in FIG. 11 (d), the width w ₁ of the core 103b is smaller than the clear width of the central portion 90c of the product (w-2t), there is space 105 Dimensional accuracy is poor. That is, FIG.
As shown in (1), the material is bent inside the space 105 to form a wrinkle 112, so that a predetermined radius of the corner 113 cannot be obtained. This poor dimensional accuracy is more likely to occur as the thickness / outer diameter ratio t / D of the raw tube 100 is smaller. According to the experience of the present inventor, it is particularly remarkable under the condition of t / D ≦ 0.03.

The third problem is that the cores 103 and 104 need to be prepared for each shape of the deformed pipe of the product, and the production cost increases. The fourth problem is that since the deformed tube after flattening is held by the cores 103 and 104, it takes time to remove the core.

A fifth problem is that the shape of the deformed tube of the product is limited to a shape from which the core can be extracted. For example, when the height h of the central portion 90c of the deformed tube 90 increases or decreases in the longitudinal direction, the core 103 cannot be removed. Further, even if the height h is constant in the longitudinal direction, the core 103 cannot be removed if the central portion 90c of the irregularly shaped tube 90 has a complicatedly curved shape in the longitudinal direction.

The problems relating to the core have been described above by taking the bending and flattening of the pipe as an example. However, these are not limited to the bending and flattening, and are not limited to the pipe forming method using the core. Needless to say, there are similar problems.

[0025]

To summarize the above-mentioned problems in the conventional pipe machining using the above-mentioned core, the problem common to the conventional core is that the core only serves as a stopper. That is, the necessary pressure cannot be positively applied to the entire inner surface of the pipe in the processing area during the processing.

The present inventor has repeatedly studied the structure of a core that can solve this problem, and as a result, came to the idea of a bag-shaped or cylindrical elastic core that can expand and contract in the circumferential direction by internal pressure. Was. The present invention has been made based on this, and the gist lies in the following metal pipe processing cores (1) to (3) and the following plastic deformation processing method (4) for metal pipes. (1) a tubular or bag-shaped hollow body made of an elastic material;
A core for processing a metal pipe, comprising: a fluid supply means for supplying and discharging a fluid for expanding the peripheral length of the hollow body into and out of the internal space. (2) The metal pipe according to (1), wherein the elastic material is an elastic material in which a reinforcing member that suppresses axial expansion of the hollow body during a fluid pressure supplied to the internal space of the hollow body is embedded. Core for processing. (3) In the internal space of the hollow body, a reinforcing member that suppresses axial expansion of the hollow body during a fluid pressure action supplied to the internal space of the hollow body is stretched in the spatial axial direction. )
Or the core for metal pipe processing as described in (2). (4) When processing a metal pipe into various shapes using a molding die, the above-mentioned (1) to (1) to
(3) placing the core for metal pipe processing according to any of (3),
A metal pipe is supplied to the internal space with a pressure that does not cause plastic deformation of the metal pipe, expands the hollow body made of an elastic material, makes its outer peripheral surface adhere to the inner peripheral surface of the metal pipe, and then performs predetermined processing. Processing method.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The core of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 shows a core according to the present invention, and FIGS. 1 (a) and 1 (b) are partial longitudinal sectional views showing one example thereof.

The core 10 shown in FIG. 1 (a) has inner ends 2 and 20 at both ends of a cylindrical hollow body 1 made of an elastic material (hereinafter also referred to as a cylindrical elastic body 1 or an elastic body 1). And the outer receiving fitting 3, and the outer receiving fitting is tightened with the nut 4 attached to the inner receiving fitting screw portions 2 b and 20 b, and the cylindrical elastic body 1 is clamped by the inner receiving fitting taper portions 2 a and 20 a and the outer receiving fitting inner taper portion 3 a. It is a structure that it is clamped and fixed from inside and outside so that it does not come off.

In order to strengthen the fixing, screw-shaped concave and convex patterns may be provided on the tapered portions 2a and 20a of the inner receiving member and the tapered portion 3a of the inner surface of the outer receiving member. The fixing method in FIG. 1 is only an example, and other methods may be used.

One of the inner receiving members 2 includes a cylindrical elastic body 1.
Is provided with a through-flow channel 2c which constitutes a fluid supply means for supplying and discharging a fluid to and from the internal space of the pipe, and a base 5 of a pipe 6 connected to a pressure applying means such as a pump (not shown).
Is connected to the inner metal fitting screw portion 2 a, a liquid such as water is introduced from the pipe 6 into the cylindrical elastic body 1.

The cylindrical elastic body 1 having an outer diameter d is made of a material having elasticity and flexibility, such as rubber, plastic, or leather, and expands as indicated by a broken line by liquid pressure.
As will be described later, the outer diameter d ₁ at the time of expansion is the inner diameter of the pipe to be processed, so that the tubular elastic body 1 does not burst even if expansion and contraction are repeated, that is, d ₁ / d is within an allowable range. Select the d dimension to fit.

The core 20 shown in FIG. 1B is composed of a tubular hollow body 11 (hereinafter also referred to as a bag-like elastic body 11 or an elastic body 11) made of an elastic material.
The method of sealing the end on the opening side and the method of connecting with the pipe 6 are the same as those of the core 10 in FIG.

The bag-like elastic body 11 is made of a material having elasticity and flexibility such as rubber, plastic, and leather, like the above-mentioned tubular elastic body 1, and is formed by the pressure of the liquid introduced into the inside. It expands from the diameter d to the outer diameter d ₁ indicated by broken lines.

The elastic members 1 and 1 when the hydraulic pressure is applied
1, a tensile force acts not only in the radial direction but also in the axial direction. When extended in the axial direction, the elastic bodies 1 and 11 when expanded
Of the elastic members 1 and 11 may be impaired in durability.

There are two methods for suppressing the elongation of the elastic bodies 1 and 11 in the axial direction. The first method is a method of embedding a reinforcing material in the elastic material constituting the elastic bodies 1 and 11, and the second method is that a reinforcing member different from the elastic bodies 1 and 11 is provided in the internal space of the elastic bodies 1 and 11. It is a method of mounting and disposing inside.

FIG. 2A shows an example of the first method.
FIG. 3 is a perspective view of a cross section of a body portion of the elastic bodies 1 and 11, in which a reinforcing member 7 such as a metal wire or a fiber thread is embedded in an axial direction.

FIG. 2 (b) shows another example of the first method, and is a partial longitudinal sectional view of the body of the elastic bodies 1 and 11, in which a net-like reinforcing member 8 made of a metal wire or fiber yarn is used. This is an embedded example. In the case of FIG. 2B, it is desirable to reduce the angle α in order to facilitate expansion in the circumferential direction. When the bag-like elastic body 11 is reinforced by the method shown in FIG. 2, it is desirable to embed the reinforcing member 7 or 8 also in the bottom portion 11b in FIG.

FIG. 3A shows an example of the second method.
In particular, there is a preferred example in which the present invention is applied to the tubular elastic body 1. In the core 30 to which the second method is applied, the inner receiving members 2 and 20 are connected by a reinforcing member 31 made of a stranded wire such as a metal wire. With the structure, the axial expansion of the cylindrical elastic body 1 is suppressed by the reinforcing member 31. Here, the reason why the stranded wire is used as the reinforcing member 31 is to give the core 30 flexibility so that the core 30 can be used for bending or the like.

FIG. 3 (b) shows another example of the second method, which is also suitable for the cylindrical elastic body 1, and the core 40 to which the second method is applied is shown in FIG. 3A, the inner receiving metal fittings 2 and 20 of the core 30 are integrated into an inner receiving metal fitting 41. The inner receiving metal fitting 41 prevents the cylindrical elastic body 1 from extending in the axial direction.

The cylindrical elastic body 1 is formed by the tapered portions 41a at both ends of the inner receiving member 41 and the inner surface tapered portion 3a of the outer receiving member 3.
Is the same as that shown in FIG. Cylindrical elastic body 1
Is applied to the space 42 between the inner receiving body 41d and the tubular elastic body 1 through the flow path 41c. The cross-sectional shape of the inner metal shell 41d is generally circular, but is not limited thereto, and may be an arbitrary shape such as a rectangle or an ellipse. The core 40 has no flexibility and is used for flattening a straight metal tube.

The structure for suppressing the axial expansion of the elastic body shown in FIGS. 3A and 3B is also applicable to the case of the core 20 shown in FIG. 1B. That is, the bottom 11 of the bag-shaped elastic body 11
b Attach a small-diameter mounting bracket to the center part so as to be able to maintain airtightness, and connect this mounting bracket and the inner receiving bracket 2 with a reinforcing member 31 made of a stranded wire such as a metal wire. When the reinforcing member has the same structure as the inner receiving member 41 shown in FIG. 3 (b), the left end of the inner receiving member 41 is formed into a small diameter equal to or less than the inner receiving member body 41d, and the leading end thereof is formed. A small-diameter screw shaft portion is formed by projecting at the center of the surface, and this screw shaft portion is attached to the center of the bottom 11b of the bag-like elastic body 11 so as to be airtightly held with respect to the mounting bracket.

It goes without saying that the above two methods of suppressing the elastic body from expanding in the axial direction may be used in combination.

Next, using the core 10 shown in FIG. 1A as an example, a method of using the core 10 and a method of processing a metal pipe will be described.

FIG. 4 shows a case where the core 10 is applied to bending of a metal tube by the draw bend method shown in FIG.
In FIG. 4, portions that are not necessary for description are not shown.

FIG. 4A shows a state in which a tube 60 is bent and a die 61 is formed.
After being held by the clamp die 64, the wiper die 67, and the pressure die 68, the core 10 is inserted into the pipe 60, the pressure of the liquid injected into the cylindrical elastic body 1 from the pipe 6 is increased to a predetermined value. 5 shows a state where the expanded tubular elastic body 1 is brought into close contact with the inner surface of the tube.

At this time, the inner side of the tubular elastic body 1 is protruded beyond the bending start point P so that an internal pressure can be applied to the pipe 60 in the buckling (wrinkle) danger portion from the bending start point P to the wiper die 67. The position of the child 10 is set. The hydraulic pressure applied to the cylindrical elastic body 1 is set to a size that can prevent the wrinkles 50 and the poor flat shape 51 shown in FIG. 7 and that the pipe 60 does not expand due to plastic deformation.

As described with reference to FIG. 8, the bending is performed by rotating the bending die 61 and moving the pressure die 68 in the moving direction of the tube 60 at the same time. At this time,
The core 10 advances with the pipe 60 and the pipe 6, and the cylindrical elastic body 1 is bent together with the pipe 60.

FIG. 4B shows a state in which the bending is completed. At this stage, the length L of the effective portion of the tubular elastic body 1 is set so that the rear end side of the tubular elastic body 1 can apply internal pressure to the pipe at the buckling occurrence danger portion from the bending start point P to the wiper die 67. FIG. 1A is set in advance.

Next, the hydraulic pressure inside the cylindrical elastic body 1 is reduced to contract radially, the clamp die 64 and the pressure die 68 are retracted by the cylinders 65 and 69, and the bent pipe 60a is moved by a device (not shown) with an arrow. By moving the core 10 in the bending direction 60a
Extract from The core 10 can be removed by pulling the pipe 6 backward.

When the bending tube 60a is to be bent for the second time, the bending tube 60a is set as shown in FIG.
The bending may be started after the tubular elastic body 1 is expanded as in the case of FIG.

Core 1 instead of plug 71 in FIG.
There are two advantages to using 0. The first advantage is that the core 10 does not have to worry about scratching the inner surface of the tube, and lubrication between the core and the tube is unnecessary. The second advantage is that even if the diameter and the wall thickness of the tube 60 change, they can be used as long as the tubular elastic body 1 can expand.

FIG. 5 shows a case where the core 10 is applied to the bending of a metal tube by the press bending method shown in FIG.

FIG. 5A shows a state in which the tube 80 is set in a die 83, liquid is injected from the tube 6 into the core 10 inserted in the tube, the liquid pressure is increased to a predetermined value, and the expanded cylindrical elastic body is expanded. 1 shows a state where 1 is brought into close contact with the inner surface of the tube. At this time, the cylindrical elastic body 1
The hydraulic pressure applied to the pipe is set to a size that can prevent the wrinkles 50 and the flat shape defect 51 shown in FIG. 7 and that the pipe 60 does not expand due to plastic deformation.

Next, the bending mold 82 is lowered, and FIG.
Bending is performed as shown in FIG. The cylindrical elastic body 1 is also bent together with the pipe 80, and the processing proceeds while the entire inner surface of the bent portion of the pipe is subjected to the internal pressure. Therefore, the wrinkles 50 and the flat shape defect 51 shown in FIG. 7 are prevented. The length L (see FIG. 1A) of the effective portion of the tubular elastic body 1 is selected so as to support the entire bending area from the inner surface. Since the pipe 6 is bent as the bending progresses, the pipe 6 is desirably flexible such as a pressure-resistant resin hose.

After the bending, the internal pressure of the tubular elastic body 1 is reduced and contracted, and the core 10 is extracted from the bending tube 80b. The advantage of using the core 10 instead of filling the granular material 81 in FIG. 9 is that the core 10 can be easily taken in and out, and workability and economy are excellent.

FIG. 6 shows a case where the core 10 is applied to flattening of the metal tube shown in FIG. FIG. 6 (a) shows the tube 1
00 is set in the lower mold 101 and the core 10 inserted into the tube
1 shows a state in which a liquid is injected from a pipe 6 into a pipe, the liquid pressure is increased to a predetermined value, and the expanded tubular elastic body 1 is brought into close contact with the inner surface of the pipe.
At this time, the hydraulic pressure applied to the cylindrical elastic body 1 is kept within a range where the pipe 100 does not expand due to plastic deformation.

Next, when the upper mold 102 is lowered, FIG.
As shown in (b), the tubular elastic body 1 is flattened together with the pipe. Since the inner surface of the pipe in the processing area is always held in a state of being pressed from the cylindrical elastic body 1, the flat defect 1 shown in FIG.
11 and wrinkles 112 can be prevented from occurring.

After processing, the internal pressure of the tubular elastic body 1 is reduced and contracted, and the core 10 is extracted from the deformed pipe 90. That is, the core 10 is provided at both ends, in particular, at the left end of the outer receiving fitting 3
Since the outer diameter of the nut 4 is smaller than the inner height (h-2t) of the central portion 90c (see FIG. 10) of the product, the inner pressure can be removed without any problem by reducing the inner pressure. .

The advantage of using the core 10 in place of the core 103 in FIG. 11 is that the core 10 can be shared even if the cross-sectional shape of the flat portion of the deformed tube 90 changes, so that it is economical. The core removal operation from the deformed pipe 90 after the processing can be performed quickly, and the processing efficiency is improved.

The above description has been made with reference to the core 10 shown in FIG. 1A as an example. The core 10, the core 20 shown in FIG. 1B, the core 30 shown in FIG. The core 40 shown in FIG. 3B is formed by bending shown in FIGS.
Can be applied to any of the flattening shown in FIG. However, FIG.
As described above, the cores 10, 30, and 40 used in the flattening shown in FIG. 10 have the outer diameters of the outer metal fittings 3 and the nut 4 on the left end side, and the center part 90c of the product (see FIG. 10).
Must be smaller than the inner height (h−2t). However, depending on the product shape to be obtained by flattening, the outer diameter of the outer receiving metal fitting 3 and the nut 4 on the left end side cannot be made smaller than the inner height (h-2t) or the core 40 cannot be used. However, in this case, the core 20 shown in FIG. 1B may be used.

[0062]

<Embodiment 1> A core 10 shown in FIG.
The tubular elastic body 1 is a piano wire (SWP, tensile strength 2400MP) having a diameter of 0.6 mm specified in JIS G 3522.
a) 24 cores made of rubber embedded at equal intervals in the circumferential direction, having an outer diameter d of 40 mm, a wall thickness of 3 mm, and an effective portion length L of 200 mm were prepared.

The prepared core is a stainless steel pipe (SUS304TK, yield strength 260 mm) having an outer diameter of 50.8 mm and a wall thickness of 1 mm and specified in JIS G 3446 and specified in JIS G 3446.
MPa and a tensile strength of 640 MPa) were used for bending at a bending radius R of 75 mm and a bending angle θ of 90 ° by the draw bend method shown in FIG.

At this time, a water emulsion containing a rust preventive agent is supplied to the internal space of the cylindrical elastic body 1 so that the internal pressure is 10 MPa.
In (a), the outer peripheral surface of the cylindrical elastic body 1 having an effective portion length of 200 mm was brought into close contact with the inner surface of the stainless steel pipe.

As a result, neither wrinkles nor flat shape defects occurred, and there were no scratches on the inner surface of the tube. On the other hand, when the same bending as described above was performed using the plug 71 shown in FIG. 8, an expensive titanium carbide coated plug and plug were used to prevent the inner surface of the pipe from being scratched by the plug. Lubricating oil supply to the surface was required.

<< Embodiment 2 >> The core 30 shown in FIG.
The cylindrical elastic body 1 is made of rubber, and the reinforcing member 31 has a diameter of 6.3.
mm of steel wire rope, and the outer diameter d of the cylindrical elastic body 1.
Is 50 mm, wall thickness is 3 mm, and effective part length L is 200 m
m core was prepared.

The prepared core was a carbon steel pipe for machine structure (STKM11A, yield strength 290MP) having an outer diameter of 60.5mm and a wall thickness of 1.6mm as defined in JIS G 3445.
a, the tensile strength of 350 MPa) was determined by the press bend method shown in FIG.
° used for bending.

At this time, a water emulsion containing a rust preventive agent is supplied to the internal space of the cylindrical elastic body 1 so that the internal pressure is 15MPa.
In (a), the outer peripheral surface of the cylindrical elastic body 1 having an effective portion length of 200 mm was brought into close contact with the inner surface of the carbon steel pipe.

As a result, neither wrinkles nor flat shape defects occurred. On the other hand, the same bending as above,
When the method of filling the pipe with sand shown in FIG. 8 is used, wrinkles are generated, and the wall thickness of the steel pipe needs to be 2 mm or more to prevent the wrinkles.

<< Embodiment 3 >> The core 40 shown in FIG.
The outer diameter of the outer receiving metal fittings 3 at both ends is 24.2 mm, and the outer diameter of the nut 4 is 24 mm.
m, made of rubber with a thickness of 5 mm, and the length L of the effective portion is 5
A core equipped with a 50 mm cylindrical elastic body 1 was prepared.

The prepared core has an outer diameter of 76.3 mm and a wall thickness of 1.2 m instead of the flat core 103 shown in FIG.
m is inserted into a carbon steel pipe for machine structure (STKM13A, yield point 300 MPa, tensile strength 410 MPa) specified in JIS G 3445, w is 100 mm, h is 2
7.5 mm, L ₁ is 300 mm, L ₂ is 450mm Figure 1
0 was used for flattening a deformed pipe having the shape shown in FIG.

At this time, a water emulsion containing a rust preventive agent is supplied to the internal space of the cylindrical elastic body 1 so that the internal pressure is 12MPa.
In a, the outer peripheral surface of the region having a body length of 500 mm was brought into close contact with the inner surface of the carbon steel pipe.

As a result, a desired deformed pipe was obtained in which the flatness of the flat portion was good and the radius of curvature of the corner portion 113 was 9 mm. On the other hand, a deformed tube having the same dimensions as above was flattened using the core 103 shown in FIG. 11 having w ₁ of 64 mm and h ₁ of 25.1 mm, and as a result, FIG.
The flat defects and wrinkles shown in (b) and (c) occurred.

[0074]

The core for processing metal pipes of the present invention is extremely effective not only for preventing the occurrence of wrinkles and shape defects in bending and flattening of pipes, but also for producing processed products having various cross-sectional dimensions. It is economical because it can be shared. Further, according to the method for processing a metal pipe of the present invention, in addition to the reduction of tool cost by sharing the core, the insertion and discharge of the core can be performed quickly, so that the work efficiency is improved and the production cost of the product can be reduced. .

[Brief description of the drawings]

1A and 1B show a core according to the present invention.
FIG. 2 is a partial vertical sectional view showing one example.

FIGS. 2A and 2B are views showing a method of reinforcing an elastic body constituting a core according to the present invention, and FIGS.

FIGS. 3A and 3B are diagrams showing another method of reinforcing the elastic body constituting the core of the present invention, and FIGS.

FIGS. 4A and 4B are diagrams showing an embodiment of bending a pipe by a draw bend method using a core of the present invention, wherein FIG. 4A shows a state before bending, FIG. 4B shows a state after bending is completed, Figure (c)
FIG. 4 is a diagram showing a state before bending when the same pipe is subjected to bending again.

FIGS. 5A and 5B are diagrams showing a bending state of a pipe by a press bending method using a core according to the present invention, wherein FIG. 5A shows a state before bending and FIG. 5B shows a state after bending is completed. FIG.

FIGS. 6A and 6B are views showing the processing of a deformed pipe by the flattening method using the core of the present invention, wherein FIG. 6A shows a state before flattening and FIG. 6B shows a state after flattening is completed. FIG.

7A and 7B are diagrams illustrating a defect phenomenon in bending of a pipe, wherein FIG. 7A illustrates a wrinkle defect, and FIG. 7B illustrates a flat defect.

FIGS. 8A and 8B are diagrams showing a bending process of a pipe by a conventional draw bend method, wherein FIG. 8A shows a state before bending, and FIG. 8B shows a state before bending viewed from the pipe tip side. FIG. 2C is a view showing a state after the completion of the bending process.

FIGS. 9A and 9B are diagrams showing a bending state of a pipe by a conventional press bending method, in which FIG. 9A shows a state before bending and FIG. 9B shows a state before bending viewed from the pipe end side. FIG. 2C is a view showing a state after the completion of the bending process.

FIGS. 10A and 10B are views showing an example of a deformed pipe, wherein FIG. 10A is a perspective view, FIG. 10B is a plan view, and FIG. 10C is a side view.

11A and 11B are views showing a conventional flattening method for a deformed pipe, in which FIG. 11A is a longitudinal sectional view showing a state before flattening, and FIG.
FIG. 3A is a cross-sectional view taken along the line II in FIG. 3A, FIG. 3C is a vertical cross-sectional view showing a state after completion of flattening, and FIG.
FIG.

12A and 12B are diagrams for explaining a defect phenomenon in the flattening method of a conventional deformed pipe, wherein FIG. 12A shows a state in the middle stage of flattening, FIG. 12B shows a flattened defect, and FIG. It is a figure which shows a wrinkle and the molding defect of a corner part.

[Explanation of symbols]

 1: cylindrical elastic body, 7: reinforcing member (metal wire or fiber), 8: reinforcing member (metal wire or fiber net), 10: core of the present invention, 11: bag-like elastic body, 20, 30: Other core of the present invention, 31: Reinforcing member (stranded wire), 40: Another example of the core of the present invention, 50: Wrinkle in bending, 51: Flat shape defect in bending, 71: Plug: 81: granular packing; 90: deformed tube; 111: poor flatness; 112: wrinkle.

Claims (4)

[Claims] 1. A metal pipe processing machine comprising: a tubular or bag-shaped hollow body made of an elastic material; and a fluid supply means for supplying and discharging a fluid for expanding the circumference of the hollow body to an internal space thereof. Nakako. 2. The metal according to claim 1, wherein the elastic material is an elastic material in which a reinforcing member for suppressing axial expansion of the hollow body during a fluid pressure supplied to an internal space of the hollow body is embedded. Core for pipe processing. 3. A reinforcing member for suppressing the axial expansion of the hollow body during the action of fluid pressure supplied to the internal space of the hollow body in the space of the hollow body. Item 3. A metal tube processing core according to item 1 or 2. 4. A metal pipe processing core according to claim 1, wherein the metal pipe is processed into various shapes by using a molding die. And
A metal pipe is supplied to the internal space with a pressure that does not cause plastic deformation of the metal pipe, expands the hollow body made of an elastic material, makes its outer peripheral surface adhere to the inner peripheral surface of the metal pipe, and then performs predetermined processing. Processing method.