JPH0741315B2 - Bent pipe manufacturing method and bent pipe - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a bent pipe having short pipes at both ends of the pipe and a product thereof.

[0002]

2. Description of the Related Art A conventional method for manufacturing a bent pipe and a bent pipe manufactured by the manufacturing method will be described with reference to the drawings.
As shown in FIG. 11, the end 10-2 of the straight pipe is cut diagonally to make an intermediate processed material 10-1. In this example, the end portion is cut at about 45 ° with respect to the center line 31 of the intermediate processed material 10-1. In this cutting direction, the inside corresponding portion 10-3 after bending becomes shorter in the longitudinal direction of the intermediate processed material 10-1, and the corresponding outside portion 10-4 after bending becomes longer in the longitudinal direction of the intermediate processed material 10-1. like,
It is symmetrical with respect to the cutting plane S that cuts the longitudinal direction of the intermediate processed material 10-1 at a right angle.

As shown in FIG. 12, the intermediate processed material 10-1 has a circular cross section. The thus-prepared intermediate processed material 10-1 is bent by a bending machine so that the inside corresponding portion 10-3 is bent inside. At this time, a core metal is used because the bending radius is usually small. FIG. 13 is a side view of the bent pipe W thus formed,
The end faces 10-2-1 on both sides of the product are orthogonal to each other, and the inner portion 10-3-1 and the radius r2 are located at a position of a radius r1 centering on the intersection O thereof.
The outer portion 10-4-1 exists at the position. This middle intersection O
The cross section DD of the bent tube W cut by a plane passing through is circular as shown in FIG.

[0004]

A straight pipe is welded to the end of the bent pipe as described above. The shape of such a bent pipe is defined as the Japanese Industrial Standard (JIS). In recent years, with regard to pipe welding, as the construction quality has become faster and the shortage of construction engineers has become more and more serious, this construction has changed from human hands to the age of automatic welding using computers. However, in order to meet this need, there are many surfaces which are not adapted to the construction of automatic welding by the conventional shape and welding joint set in JIS standard.
There are the following problems in automatically welding the bent pipe W.

FIG. 15 shows a bent pipe W constructed as shown in FIG.
The method for automatically welding the straight pipe WS is shown in FIG. Curved pipe W
The end faces of the straight pipe WS and the straight pipe WS are butted, the straight pipe WS is fixed by a fixture G, and the bent pipe W is fixed by a fixture not shown. For welding, the welding electrode F is automatically welded by rotating around the welded portion WE. In this way, it is difficult to fix the bent pipe W,
Even for curved pipes having the same diameter, it is necessary to change the fixture every time the radius of the curved pipe W is different. Further, when welding a titanium alloy pipe or the like, it is preferable to shield the weld WE from the atmosphere side, but it is difficult to dispose a member that shields the weld WE from the atmosphere side. This difficulty is especially great when welding curved pipes.

It is an object of the present invention to provide a bent pipe which facilitates automatic welding of the bent pipe to another pipe and a method for manufacturing the bent pipe.

[0007]

A first aspect of the present invention is a method of manufacturing a hollow bent pipe having a cylindrical cross section, wherein the both ends are in the same center line by bulging, and the intermediate part is One side cut by a plane including the center lines of both ends is a semicircle having the same diameter as the both ends, and the other side is an bulge that becomes an oval including the semicircular portion, and the bulge The length of the ellipse in the part gradually increases toward the middle part following both ends, and a hollow intermediate processed material having a shape that maximizes in the central part in the direction connecting the both ends is manufactured. A method of manufacturing a bent pipe, characterized in that bending is performed with the bulge portion outside, and short pipe portions are integrally formed at both ends of the bent portion of the pipe.

A second aspect of the present invention is a cylindrical shape in which both ends are on the same center line by bulging, and one side of which the middle part is cut by a plane including the center lines of the both ends has the same diameter as the both ends. A semi-circular shape is used, and the other side is made into a bulging portion that becomes an elliptical shape including the semi-circular portion, and the length of the ellipse in the bulging portion gradually increases toward the middle portion following both ends. , A hollow intermediate processed material having the maximum shape in the central part in the direction of connecting the both ends is manufactured, and bending is performed with the bulging portion of the intermediate processed material facing outward, at both ends of the bent part of the obtained pipe. It is a bent pipe characterized in that a straight short pipe is integrally molded.

[0009]

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

FIG. 1 shows a bent pipe NW. Curved pipe N
In W, a straight tube short tube portion 3 is integrally formed following a boundary line 2 of the bent portion 1 which is bent 90 degrees and ends, and an end portion of the short tube portion 3 is an opening 3a. The extensions of the two boundary lines 2 in the figure are orthogonal to each other at an intersection O, and the bending portion 1 is bent at an inner radius r1 and an outer radius r2 with the intersection O as the center. The AA cross section of the bent portion 1 passing through the intersection O is a hollow circle as shown in FIG.

Next, a method of manufacturing the bent pipe NW will be described. The bent pipe NW is manufactured by first manufacturing the intermediate processed material 4 shown in FIGS. The shape of the intermediate processed material 4 is a cylinder having both ends 4a having a center line 5, and the intermediate part 4b is cut at a plane perpendicular to the plane of the drawing including the center line 5 of both ends 4a.
a semi-cylindrical portion 4b-1 having the same shape as that of a and having both end portions 4a
It is a semi-cylindrical shape over the entire length up to. The other one side is a bulging portion 4b that is an elliptical shape including the semicircular portion 4b-1 on the one side.
It is -2. The length of the ellipse in the bulging portion 4b-2 gradually increases toward the central portion following both ends 4a,
It is maximum at the center of the direction connecting both ends.

The intermediate processed material 4 is manufactured by bulge processing. That is, the bulging portion 4b-2 is inflated. As a method for inflating the bulging portion 4b-2, urethane, liquid pressure, roll, mold, etc. may be used.
When the curvature of bending around the intersection point O is small, the bulging portion 4b-2 has a large bulge, so it is preferable to use hydraulic pressure.

5 and 6 show a method of manufacturing the intermediate processed material 4 by hydraulic pressure. A straight pipe blank (blank) 6 to which a compression length ΔL / 2 necessary to obtain the required wall thickness of the bulging portion 4b-2 is added to the total length L of the intermediate processed material 4 is fitted into the mold 7. To meet. The diameter of the raw pipe 6 is the same as the diameter of both ends 4a. The mold 7 has the compression length ΔL / 2 and the length L1 of the fitting portion 7a into which the working body 8 is fitted, on both end sides of the mold portion having the same outer dimensions as the intermediate processed material 4. The action body 8 is provided with an oil passage 9 through which pressure oil, for example, pressure oil, which pressure oil flows from the pressure source P in the direction of the arrow, is supplied into the raw pipe 6. A force is applied to the action body 8 in the direction of arrow A by the pressure means 11, and the pressure means 11 on both sides are synchronized by the synchronization means 12.
Therefore, the action body 8 is pressed at the same speed and with the same force. A hydraulic cylinder, a toggle mechanism or the like is used as the pressurizing means 11, and when the pressurizing means 11 uses pressure oil as the synchronizing means, a servo mechanism, a hydraulic pressure tuning circuit, a mechanical connecting means such as one pinion. To engage the racks fixed to the hydraulic cylinders on both sides,
When the toggle mechanism is a pressurizing means, a bell crank and a connecting rod for connecting the bell crank are provided. Since these are well known, their description is omitted.

The pressurizing means 11 pushes the working body 8 in the direction of arrow A and sends pressure oil from the pressure source P into the raw pipe 6 through the oil passage 9. This pressure is, for example, 2000 kg / c
m ² . As a result, one side of the raw pipe 6 swells and presses against the mold 7 to form a bulging portion 4b-2 (FIG. 6). Mold 7
When the processed member is removed, it becomes the intermediate processed material 4 in FIG.

Next, bending is performed with the bulged portion 4b-2 of the intermediate processed material 4 facing outward. This bending is performed by press bending using, for example, a mandrel. FIG. 7 shows bending. As shown in the drawing, the semi-circular portion 4b-1 of the intermediate processed material is fitted into the forming die 12, and the mandrel 13 is fitted into both end parts 4a respectively so that the mandrel 13 approaches or contacts. The pressing die 14 is applied to both ends 4a and a part of the bulging portion 4b-2. And, for example, the sliding member 16 and the mandrel 1 which are fitted to the mandrel guide 15
The rear end of 3 is connected to pin 17. Then, the pressing die 14 is rotated in the direction of the arrow B and the slider 16 is slid to move the mandrel 1
While rotating 3 in the direction of arrow C, it moves in the direction of arrow D with respect to the intermediate processed material 4. As a result, the bent pipe N of FIG.
W is obtained.

FIG. 8 shows a method for automatically welding the bent pipe NW and the straight pipe WS. As shown in the figure, the chamber has a fitting portion 19a, 19b that fits the short pipe portion 3 of the bent pipe NW and the outer periphery of the end portion of the straight pipe WS, and is a closed chamber having a chamber 18 surrounding the welding portion WE. From both sides of 19, the short pipe part 3 of the bent pipe NW
Further, the ends of the straight pipe WS are inserted and abutted, and the chamber 19, the bent pipe NW, and the straight pipe WS are relatively rotatable about the center line 21. An electrode F is inserted into the chamber 19 from the radial direction. While rotating the chamber 19 or the bent pipe NW and the straight pipe WS, the electrode (wire) F
When the bias is applied, the bent pipe NW and the straight pipe WS are welded. At this time, if an inert gas such as nitrogen gas is sent to the chamber 18, even if the bent pipe NW and the straight pipe WS are made of titanium alloy or the like, which are difficult to weld, they can be surely welded.

FIG. 9 shows another method of manufacturing an intermediate processed material,
In this method, the blank tube is processed as in FIG. 11 to form the first intermediate processed material 22. That is, the first intermediate processed material 22 is similar to that shown in FIG. 11, and the working body 8 is provided with the end faces contacting both end surfaces of the intermediate processed material 22. According to this embodiment, the intermediate processed material 4 can avoid thinning of the bulging portion 4b-2.

FIG. 10 shows an example in which bent pipes NW are welded to each other. In such a case, the bent pipe of the conventional example is extremely difficult to hold, but in this example, the welded portion can be easily held.

[0019]

EFFECTS OF THE INVENTION Since the bent pipe of the present invention has short pipe portions at both ends of the bent pipe portion, according to this product, when welding the short pipe portion and the bent pipe, an inert gas is present inside. Since a flexible chamber can be provided so as to surround the pipe, it is possible to automatically weld a bent pipe made of a titanium alloy material to another pipe. Therefore, even a non-expert can accurately and quickly weld a large number of bent pipes and straight pipes. Further, since an inert gas is used, it is possible to easily weld a bent pipe and a straight pipe made of a titanium alloy or the like.
According to the present invention, since both sides of the welded portion are straight pipes having the same diameter, it is easy to mount and hold them.

According to the method for manufacturing a bent pipe of the present invention, since the whole raw pipe is used from the raw pipe to the product, there is no waste of material. It is easy to manufacture the intermediate processed material from the raw pipe by providing the short pipe portions at both ends of the intermediate processed material by bulging.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical cross-sectional view of an intermediate processed material.

FIG. 4 is a sectional view taken along line BB of FIG.

FIG. 5 is a vertical cross-sectional view showing a first step of a manufacturing method of an intermediate processed material.

FIG. 6 is a vertical sectional view showing a final step of a method for manufacturing an intermediate processed material.

FIG. 7 is a horizontal sectional view showing a step of bending an intermediate processed material.

FIG. 8 is a plan view showing a method of welding a bent pipe and a straight pipe of the present invention in a partial cross section.

FIG. 9 is a vertical cross-sectional view showing another method for manufacturing an intermediate processed material.

FIG. 10 is a plan view showing a partial cross-section of the welding of curved pipes.

FIG. 11 is a vertical cross-sectional view of an intermediate processed material when manufacturing a bent pipe of a conventional example.

12 is a cross-sectional view taken along line CC of FIG.

FIG. 13 is a side view of a conventional bent pipe.

14 is a cross-sectional view taken along the line DD of FIG.

FIG. 15 is a plan view showing a method for welding a bent pipe and a straight pipe in a conventional example.

[Explanation of symbols]

 1 Bent part 2 Boundary line 3 Short pipe part 4 Intermediate processed material

Claims (2)

[Claims] 1. A method for producing a hollow curved pipe having a cylindrical cross section, wherein the bulge process is a cylindrical shape having both ends on the same center line, and an intermediate part is cut along a plane including the center lines of the both ends. Is a semicircular shape having the same diameter as the both end portions, and the other one side is an bulging portion that is an elliptical shape including the semicircular portion, and the length of the ellipse in the bulging portion is continuous with both end portions. Gradually becomes larger toward the intermediate portion, and a hollow intermediate processed material having a shape that maximizes in the central portion in the direction of connecting both ends is manufactured, and bending processing is performed with the bulging portion of the intermediate processed material being outside. A method for manufacturing a bent pipe, characterized in that short pipe parts are integrally formed at both ends of the bent part of the pipe. 2. A cylindrical shape in which both ends are on the same center line by bulging, and one side of which the middle part is cut by a plane including the center lines of the both ends has a semicircular shape having the same diameter as the both ends and One side of the bulge is an elliptical bulge including the semicircular portion, and the length of the ellipse in the bulge gradually increases toward the middle part following both ends, and the direction connecting the both ends. A hollow intermediate processed material having the maximum shape in the central part of the is manufactured, and bending is performed with the bulging portion of the intermediate processed material outside, and straight pipe short pipes are provided at both ends of the bent portion of the obtained pipe. A bent pipe characterized by being integrally molded.