JPH11197873A - Method of joining equal-diameter branch pipe to metallic pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To join a branch pipe, which has a diameter close to that of the main pipe, by means of a burring method, by drawing a semi-spherical flanging head outward from the pipe, horizontally finishing the projected part of the drawing hole, and welding the end face of the branch pipe to the upper circumferential wall of the projected part. SOLUTION: A metallic pipe 10 having a oblong hole 12 on the circumferential wall is placed horizontally on a frame 20 with the oblong hole 12 faced downward. If the oblong hole 12 matches the position of a through-hole 21 in the center of the frame, a flanging head 15 is inserted from one end of the metallic pipe 10, moved to the upper part of the hole 12 and positioned horizontally. Then, with a connector member 22 screwed onto a tapped hole at the lower end of the head 15 and connected, a hydraulic cylinder through its reduced operation gradually moves the head 15 downward through a piston rod, with the head finally drawn out of the pipe. The projecting part of that drawing hole is finished horizontally by grinding and is given edge preparation, with the end face of the branch pipe joined to the upper circumferential wall of the projecting part by butt welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a branch pipe having a diameter equal to or close to the diameter of a metal pipe such as a stainless steel pipe or an iron pipe.

[0002]

2. Description of the Related Art At the time of piping construction, 90 degrees
Use fittings such as T, Y, cross, and tees to connect elbows and vents and to join branch pipes. In the case of high-pressure piping, permanent pipe joints are used and the pipe ends are directly joined by butt welding. Therefore, conventional piping construction generally has a large number of welded joints. For example, as shown in FIG.
When the T-shaped joint 2 is connected to join the joints, butt welding is performed at three places 3a, 3b, and 3c.

[0003] In general, if there are many welding operations at the time of piping work, the efficiency of operation may be reduced, which may cause problems in terms of safety and quality maintenance. Metal pipes, especially stainless steel pipes, are very delicate materials, and if partial oxidation occurs during welding, corrosion often progresses from that point. If the smoothness of the route is hindered or the route cracks,
Corrosion starts at that point and is likely to cause a water leakage accident. For this reason, it is preferable to reduce the number of welded joints as much as possible in ordinary piping work.

[0004]

When burring is used instead of a T-shaped joint to reduce the number of welding points in piping, as shown in FIGS. 1 and 2, three welding points are obtained by simple calculation. Is effective at one place.
In the conventional burring process, a circular hole is provided at a predetermined position of the main pipe 5 as shown in FIG. 3, and the circular hole is expanded to a long hole.
After the main pipe 5 is fixed horizontally in the bridging device,
The spigot head 7 is inserted under the long hole, and is pulled out upward. When the protrusion 8 of the drawing hole is finished, the branch pipe 1 (FIG. 2) can be directly welded to the upper peripheral wall of the protrusion.

[0005] Even if this burring is effective in reducing the number of welding points, it is necessary that the branch pipe 1 that can be joined be smaller in diameter than the main pipe 5 and that the same diameter joining is impossible. Has severely limited their use. In a conventional burring process, when a drawing hole having the same diameter is to be formed by using a conical head 7 close to a conical shape as shown in FIG. 3, the plane shape of the drawing hole is distorted from a perfect circle, and a branch pipe is formed. Could not be butt welded.

[0006] The present invention has been proposed to improve the above-mentioned problems related to the conventional burring process, and an object of the present invention is to provide a method of connecting a branch pipe having a diameter close to the main pipe by the burring process. . Another object of the present invention is to provide a method of connecting a branch pipe having the same diameter as the main pipe by burring.

[0007]

In order to achieve the above object, in the pipe connection method according to the present invention, as shown in FIGS.
After a circular through hole is formed into a long hole 12, the metal tube 10 is fixed horizontally in the bridging device 14. The metal tube 10 to be applied is a stainless steel tube, a carbon steel tube, an iron tube, or the like.
mm or less.

In the spouting device 14, a substantially hemispherical spouting head 15 is inserted into the metal tube 10 and attached through the long hole 12, and then the head 15 is pulled out of the tube (see FIG. 6). As shown in FIG. 7, after the protrusion 17 of the drawing hole is horizontally finished, the end face of the branch pipe 18 is welded to the peripheral wall at the upper end of the protrusion. Preferably, the hard metal spigot head 15 is substantially hemispherical and the metal tube 1
The diameter is almost equal to the inner diameter of 0. The shape of the head 15 may be a spherical surface at least in contact with the tube wall, and may be a truncated spherical shape or a complete spherical shape in addition to a hemispherical shape.

In FIG. 4, the long hole 12 provided in the peripheral wall of the metal tube 10 has a flat shape with a central constriction close to a gourd shape, and it is preferable that the length of its long axis is shorter than the diameter of the bulging head 15. . The planar shape of the long hole 12 is the same as that of the head 1.
5 is determined so that the end faces of the hole projections 17 are as high as possible when the 5 is pulled out.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A flange device 14 used in the method of the present invention has a horizontal base 20, as shown in FIGS. 5 and 6, and a through hole 21 is provided at the center of the base. Through hole 2
The diameter of one is preferably determined to be slightly larger than the largest diameter hole projection 17 to be formed. Through hole 21
Below, a hydraulic cylinder (not shown) is installed vertically upward and a connector member 22 is rotatably connected to a piston rod of the cylinder. For example, connector member 2
2 is provided with a male screw part, and this part is fed out.
It may be screwed into a screw hole at the center of the lower end of 5, and the piston rod of the cylinder may be connected to the head 15 by other known means.

The metal tube 10 provided with the long hole 12 in the peripheral wall is
It is placed horizontally on the gantry 20 with the long hole facing downward. If the long hole 12 matches the position of the through hole 21 at the center of the gantry, the piercing head 15 is inserted from one end of the metal tube 10, and the head is moved to a position above the long hole 12 to be positioned horizontally. Next, when the connector member 22 is screwed into the lower end screw hole of the head 15 and connected, the hydraulic cylinder is reduced and the head 15 is gradually moved downward (in the direction of the arrow in FIG. 6) via the piston rod. Pull out the tube (see FIG. 6).

[0012] As shown in FIG.
Is finished by horizontal cutting and then beveling, butting against the end face of the branch pipe 18 is an outer V-shaped groove,
Re-shaped bevels may be used. It is preferable to apply a joining system in which the end face of the branch pipe 18 is joined to the upper end peripheral wall of the protruding portion 17 by butt welding, and in this welding, an inert gas is sealed in the metal pipe 10. In this joining system, an inert gas is sealed between one or more pairs of discs inside the pipes 10 and 18 to prevent oxidation of the inner peripheral surface of the steel pipe. Since the inert gas is supplied only to the inside, the filling amount is small, and the time until the oxygen concentration on the inner peripheral surface of the weld falls to a certain value or less is short.

[0013]

Next, the present invention will be described based on examples, but the present invention is not limited to the examples. The stainless steel pipe 10, which is the main pipe, has, for example, a diameter of 100 mm and a wall thickness of 2 mm, and joins a branch pipe 18 having substantially the same diameter according to a piping design drawing corresponding to a building. The stainless steel pipe 10 may be curved.

The stainless steel pipe 10 is provided with a circular through-hole 11 (FIG. 4) by a drilling machine or the like at a predetermined branch pipe joining position on the pipe wall, and the circular through-hole is expanded to the elongated hole 12 by cutting. The long hole 12 has a flat shape with a central constriction close to a gourd shape parallel to the axis, and the length of the long axis is shorter than the diameter of the head 15. Slot 12
With respect to a simple hole, the rising amount of the projecting portion 17 decreases as the distance from the center to the side peripheral end of the steel pipe 10 decreases. Therefore, by providing the constricted portions 24, 24, the end faces of the projecting portion 17 are made to have substantially the same height. Become.

As shown in FIG. 5, the steel pipe 10 provided with the long hole 12 in the peripheral wall is horizontally placed on the gantry 20 with the long hole facing downward. When the long hole 12 matches the position of the through hole 21 at the center of the gantry, the stainless steel tube 10 is fixed by a clamp (not shown), and then a hemispherical head 15 having a diameter of 100 mm is inserted from one end of the steel tube 10. Is moved to a position above the long hole 12 and is positioned horizontally. Next, the connector member 22 is screwed into the lower end screw hole of the head 15 and connected.

Next, the hydraulic cylinder is contracted to move the head 15 gradually downward as shown in FIG. 6 through the piston rod, and finally, the head 15 is pulled out of the pipe.
The projecting portion 17 of the drawing hole is formed by cold working. The outer diameter of the protruding portion 17 is 100 mm similarly to the steel pipe 10, and the wall surface of the protruding portion is smooth, and the smoothness of the inner peripheral surface of the steel pipe is not hindered.

As shown in FIG. 7, the protruding portion 17 of the drawing hole is horizontally finished by cutting, and a butt end of the branch pipe 18 with the end face is formed into an outer surface V-shaped groove. Generally, in order to join the branch pipe 18 to the steel pipe 10, the branch pipe is fixed to the steel pipe 10 by spot welding, and then the joining peripheral portion 2 of the projection 17 is joined.
5 is automatically welded. For example, in the branching welding machine, the welding torch rotates and moves along the periphery of the joint after its arm is detachably fixed to the branch pipe 18. In this welding torch, a fixed arm is attached to the branch pipe 18 above the protrusion 17 and then the upper peripheral wall of the protrusion is welded. Installed downward from the fixed arm toward the center.

Although not shown, in order to join the branch pipe 18 to the protruding portion 17, it is more preferable to apply a welding joining system in which an inert gas is sealed inside the steel pipe. This welding joining system includes a TIG or plasma arc welding machine having a torch, an indicator light such as a patrol light (trade name) indicating a weldable state, a timer for turning on the indicator light after a predetermined time has elapsed, and a pipe inner peripheral surface. And a solenoid valve for controlling gas supply between the two disks. The welding machine used may be any of a full automatic welding of a steel pipe rotating type, a semi-automatic welding, and a manual welding with a pipe fixed. The torch and the solenoid valve are connected from a gas cylinder or a centralized gas piping facility of a factory.

In the case where the steel pipe 10 to be welded and the branch pipe 18 are not long, the welding joining system fixes the branch pipe to the steel pipe 10 by spot welding, and then connects the steel pipe 10 to both ends of the steel pipe 10 and the free ends of the branch pipe 18 respectively. Press in the elastic seal. A flexible tube extends through one of the seals and connects the end of the tube to a gas cylinder via a solenoid valve.

The elastic sealing material is a disc made of aluminum or the like. The sectioning disc has a diameter slightly smaller than the inner diameter of the steel pipe 10 or the branch pipe 18 to be welded, and its periphery is surrounded by an annular rubber material or the like, and can be in close contact with the inner peripheral surface of these steel pipes. This partition disc is
A plurality of sets having different diameters are prepared according to the inner diameter of the steel pipe to be welded. The partition disk may be folded in two or formed into a disc spring shape so as to be easily inserted into the steel pipe 10. In this case, the disk is slightly deformed by pressurization with the inert gas, and comes into close contact with the inner peripheral surface of the steel pipe. Alternatively, the periphery of the disk may be surrounded by a specially shaped annular rubber material so that the disk is brought into close contact with the inner peripheral surface of the steel pipe by pressurization with an inert gas.

The flexible tube extends through the center of one of the three discs, and forms a plurality of gas flow holes in a peripheral wall between the three discs. This tube has one end connected to a gas cylinder via an electromagnetic valve, and the other end closed when the apparatus is operated. The inert gas in the cylinder is, for example, a mixed gas of argon and air, which is a shielding gas to be sent to the torch of the welding machine, and flows from the solenoid valve through the flow hole of the tube to flow between the disks to be filled.

The partition disks are pushed into both ends of the steel pipe 10 and the free ends of the branch pipes 18 respectively, and the inert gas is filled only in a necessary area inside the steel pipe by the three partition disks. Next, move the frame appropriately,
The torch of the TIG welding machine is positioned at the joint 25.
When the power switch is turned on, the gas solenoid valve and the relay are activated, the inert gas starts flowing from the cylinder through the solenoid valve, the piping and the tube between the three disks, and the first timer is excited by another relay. I do.

The first timer operates after a set time when an inert gas fills between the disks. The set time of the first timer is, for example, 30 seconds, and this set time is appropriately adjusted according to the inner diameter and length of the steel pipe 10 and the branch pipe 18 to be welded. The indicator light is turned on by the operation of the first timer, and the steel pipe 10 or the torch is horizontally rotated by the positioner while butt-welding with the torch of the TIG welding machine. When the steel pipe 10 completes one rotation and welding is completed, the switch is turned off, whereby another relay is operated to excite the second timer.

Immediately after the completion of welding, since the amount of oxygen in the internal space of the steel pipe 10 has increased, the inert gas is continuously supplied with the solenoid valve opened until the second timer is operated, and at the same time, welding is performed. Quickly cool the location with air. Thirty seconds after the completion of the cooling, the solenoid valve is closed by the operation of the second timer, the supply of the inert gas is stopped, and the indicator light is turned off. Thereafter, the other end of the tube is opened to release the inert gas inside the steel tube into the air, and the three discs are removed from the inside of the steel tube.

When this welding apparatus is a semi-automatic welding of a steel pipe rotary type by a positioner, it waits until the indicator light is turned on after the switch is turned on, and after the indicator light is turned on, it is thrust with a torch of a TIG welding machine. What is necessary is just to start joining welding. When the specified welding is completed, turn off the switch,
After the indicator light is turned off, the other end of the tube is opened to release the inert gas inside the steel tube into the air.

In this welding connection system, at the time of butt welding of the steel pipe 10, an inert gas is sealed only between the three discs in the steel pipe to prevent oxidation of the inner peripheral surface of the steel pipe. Even if the steel pipe 10 is long, the inert gas is fed only between the three disks, so that the filling amount is small, and the time required for the oxygen concentration to drop below a certain value on the welding inner peripheral surface is also short. Become. In this welding joining system, the concentration of the inert gas that can prevent the oxidation of the inner peripheral surface of the welding at the time of welding joining can be accurately confirmed with an indicator light, not simply by visual inspection.

[0027]

According to the method of the present invention, a branch pipe having a diameter close to the main pipe can be connected. According to the method of the present invention, three welding points are reduced to one in a simple calculation as compared with a T-shaped joint, which reduces welding work at the time of piping work, and is advantageous in terms of improvement of work efficiency, safety and quality maintenance. . Especially,
In piping work using stainless steel pipes, the number of welded joints is reduced, so that the progress of corrosion due to partial oxidation is significantly reduced, and the occurrence of a water leakage accident at the butt-welded joints of stainless steel pipes can be avoided.

According to the method of the present invention, a branch pipe having the same diameter as the main pipe can be connected by burring processing only by using a substantially hemispherical head that has a diameter substantially equal to the pipe inner diameter. According to the method of the present invention, since the long hole before the burring process has a flat shape with a central constriction close to a gourd shape, the end faces of the hole protrusions become almost equal when the bulging head is pulled out, A branch pipe of the same diameter can be easily connected to the main pipe.

[Brief description of the drawings]

FIG. 1 is a partial plan view showing a conventional pipe connection using a T-shaped joint.

FIG. 2 is a partial plan view showing a pipe connection portion formed by a conventional burring process.

FIG. 3 is a partial cross-sectional view showing a conventional burring process.

FIG. 4 is a partial plan view showing a long hole in the method of the present invention.

FIG. 5 is a partial sectional view showing a burring process according to the present invention.

FIG. 6 is a partial sectional view showing an embodiment of the burring process of FIG. 5;

FIG. 7 is a partial plan view showing a pipe connection portion by burring processing of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Metal tube 11 Circular through-hole 12 Elongated hole 14 Burling device 15 Burling head 17 Projection part of drawing hole 18 Branch pipe

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[Procedure amendment]

[Submission date] January 29, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Wherein the elongated hole provided in the peripheral wall of the metal tube is a flat shape with a central constriction near the gourd-shaped, rather shorter than the diameter of the major axis of the collar out head length, when the drawing
The projecting part becomes closer from the center of the long hole to the side peripheral end of the metal tube.
The rising amount of
Therefore <br/> claim 1 Symbol placement methods end face of the projection of the pull-out hole is approximately equal to the height. ────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] March 31, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 33/00 B23K 33/00 A

Claims (3)

[Claims] 1. A circular through-hole is provided at a branch pipe joining position of a metal pipe, and after the circular through-hole is formed into a long hole, the metal pipe is fixed horizontally and a substantially hemispherical head is formed on the metal pipe. It is put into the inside of the pipe and attached through the long hole, then the head is pulled out of the pipe, the protrusion of the draw hole is finished horizontally, and then the end face of the branch pipe is welded to the upper peripheral wall of the protrusion. The method of forming the tube. 2. A circular through-hole is provided at a branch pipe joining position of a metal pipe, and after the circular through-hole is cut into a long hole, the metal pipe is fixed horizontally and has a diameter substantially equal to the inner diameter of the pipe. A hemispherical head is inserted inside the metal tube and attached through a long hole, the head is pulled out at right angles from the axis of the tube, and the protrusion of the hole is horizontally finished and then the protrusion is formed. Method of connecting the same diameter branch pipe by welding the end face of the branch pipe to the upper peripheral wall of the pipe. 3. The method according to claim 1, wherein the long hole provided in the peripheral wall of the metal tube has a flat shape with a central constriction close to a gourd shape, and the length of the long axis is shorter than the diameter of the head. .