JPS61159275A - Automatic welding method - Google Patents

Abstract

PURPOSE:To improve working efficiency and welding quality by fitting externally and fixing copper backing strips which can be cooled with water onto a butt part and subjecting said part to butt welding while changing the distance between the top end of a welding torch and the inside surface of a pipe and the angle of inclination of the torch. CONSTITUTION:About 50 deg. groove is set to the butt part of an existing welded pipe 1 and an unwelded pipe 2 and the root gap is made zero. A pair of semi- toric copper backing strips 3, 3 are disposed on the outside circumference of the butt part and are fitted externally and fixed to the butt part by means of lever blocks 4. The strip 3 is formed internally with a cavity for water cooling in which the cooling water circulates. A welding head 15 is supported rotatably around the central axis of the pipe to the inside of the pipe by means of fixing legs and is driven by an electric motor 17. The welding torch 21 welds the butt part while changing the distance between the same and the inside surface of the pipe and the angle of inclination thereof in accordance with optimum conditions by the above-mentioned mechanism.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for automatically welding the abutting portions of large-diameter steel pipes from the inward side, and more specifically, the present invention relates to a method for automatically welding the abutting portions of large diameter steel pipes from the inward side. Welding conditions such as the distance between the welding torch and the inner surface of the pipe for welding the inner surface of the abutted portion are determined based on the welding conditions of the butted portion. The present invention proposes an automatic welding method that improves the quality of welding by changing the welding position according to the circumferential position, and also allows efficient welding.

(Prior art) Construction of a large diameter pipeline of about 12,000 mm is
This is done by abutting the beveled pipe ends against each other and welding the abutted portions with a welding torch that is movable in a circular motion along the inner surface of the abutting portions. As such a welding method, a method shown in a partial vertical cross-sectional view in FIG. 5 and a partial cross-sectional view in FIG. 6 is known.

As shown in Figure 5, the groove angle is approximately 30°.
Beveled on the inner surface (Steel pipe IDI and Steel pipe 1)
A steel backing metal 31 is welded to the outer periphery of the butt-l part formed by butting 02 and 02, in order to perform metal welding. Copper plate 3 for cooling in the evening
2 is fixed externally.

An automatic welding machine (not shown) is installed inside the pipe, and a welding tip 201 of the automatic welding machine faces the grooved portion so as to be movable in the circumferential direction -1. The position before the work is the position of welding 1--201, that is, the tip of the welding torch 201 as shown in FIG.
a and the torch angle α (arc radiation angle, specifically, t tangent 1 to the normal to the inner surface of the pipe as shown in FIG.
・Welding 1・-Chi 201 while changing the extension angle α) in the circumferential direction of the axis of the tip 201a of the tip 20i in accordance with the circumferential position of the butt 1 part. In this method, welding was performed by moving the weld around the entire circumference of the inner surface of the tube.

[Problem that the invention seeks to solve]

In the conventional method such as ``Togorode'' and ``2,'' 3
It is necessary to butt and fillet weld 1 to gIX,
Moreover, when performing this welding work, it is necessary to perform the core stand-1 work of both pipes 10L1.02 prior to this.

However, in the conventional method, as shown in FIG.
was about 8 mm, so both tubes 101 and +02
The alignment work involves positioning both tubes 101 and 102 in the direction of the tube axes.
This was done by temporarily welding -J with 01 and +02 straddled. For this reason, the temporary welding and fillet joint described above are required before the actual joint of the butt portion, and it is also necessary to not remove the "horse" after welding the butt port 1. As a result, a large amount of time is spent on these processes, resulting in an inability to perform efficient welding.

In addition, the backing metal 31 melts during welding of the abutting portion, and remains as a large convex portion on the outer surface of the abutting portion, deteriorating the quality of the weld finish.

[Failure to solve the problem]

The present invention has been made in view of the above circumstances, and has a groove for Uranami B IX on the tube side, and a copper stopper for water cooling rIJ function, which is attached to the tube end butt part glue (surface). An object of the present invention is to provide an automatic welding method which can form a smooth uranami bead by detachably attaching the toner to the welding device, has excellent welding finish quality, and can perform efficient welding.

The automatic welding method according to the present invention abuts the pipe ends of large-diameter steel pipes against each other, attaches a stopper to the outer surface of this abutted part, and attaches it to the orbiting bow part along the inner surface of the abutment. In the J method (in which the butt-Q section is automatically welded using a welding torch), two large-diameter steel pipes are aligned, butted, temporarily welded, and a groove for the uranami bead is formed on the pipe side. In addition, a water-coolable copper stopper is removably fixed to the outer part of the abutting part 7, and the tip of the welding part 1 and the welding part is fixed in accordance with the circumferential position of the abutting part U. The abutting portion is welded while changing the distance to the inner surface of the tube and the inclination angle of the welding torch in the circumferential direction with respect to the normal to the inner surface of the tube.

〔Example〕

The present invention will be described in detail below with reference to drawings showing examples thereof. FIG. 1 is a front view showing the implementation state of the automatic welding method according to the present invention, FIG. 2 is an enlarged view of the weld 52115 and its surroundings shown in FIG.

Straight pipes are installed by butt-welding the pipe ends to each other.
An unwelded pipe 2 of the same diameter is aligned with the unwelded side end face of a welded pipe 1 of approximately 2000 mm, and the unwelded pipe 2 is butted together, and the two are connected by temporary welding at the appropriate place within the groove of this butted part. It is. The abutting parts of the welded pipe 1 and the unwelded pipe 2 are beveled on the inner surface, and the bevel angle of 4J at the abutting part is set to be approximately 50°, and both Tube L 2 Lou! - The gear gear is targeted to be 0.1 mm, and considering the machining accuracy of the flatness of the end face, a tolerance of about +31 mm is allowed.

The outer periphery of the butting part has an appropriate width, i! Convex locking pieces 3c, 3c formed at the circumferential ends of a pair of semi-circular butts 3.3 having a thickness of i, respectively.
Both tubes I by tightening using.

It is fixedly fitted across the abutting part of 2, and when the tightening of Rehab 11 Tsuk 4.4 is released, the stopper 3°3 can be easily removed from the abutting part. There is.

As shown in FIG. 3, the dowel 3 has a copper semicircular annular member 3 with a concave cross section on one side of the inner annular copper plate 3a.
The open 1-1 end of 1) is welded, and a square hole 3d is formed approximately in the center of the cross section. Both ends in the circumferential direction of the stopper 3 in the square hole 3d are closed. On the inner surface of the copper plate 3a, the shape of the inner surface of the copper plate 3a is made into a smooth shape, and the curved surface 38 having the center of curvature on the inner surface side is made into a smooth shape, and the entire length of the curved surface 38 in the circumferential direction is It is formed by n.

There is a cylindrical supply on the side of both circumferential ends of the deposit 3.

υll water hose connections 5 and 6 are respectively taken out, and their holes communicate with the square hole 3d. A water supply hose 58 is connected to the water supply hose connection portion 5 and the 1/1 water port connection portion 6, respectively.
3. One end of the drain hose 6a is connected. The other end of the water supply hose 5a is connected to the discharge side of a water pump (not shown).
(The other end of the drain pump 6a is connected to a cooling water tank, and the cooling water 7 is circulated and supplied into the square hole 3d by driving the water pump. 3 cooling can be performed.

Inside the pipe, welding joints 1-15 are provided facing the inner surface of the pipe. The welding hem 115 is attached to a fixed leg (as shown) fixed inside the pipe.
It is supported so that it can rotate around the center of the tube.

At one end of the welding hemlock FI5 in the pipe circumferential direction, the welding hemlock 1 is attached.
It is equipped with three electric machines 17 for -15 drive. Electric motor 1
7 is driven by a signal from a drive control device H (not shown) installed outside the pipe, and applies its driving force via a gear mechanism 18 to a position near one end of the welding hem 115 in the circumferential direction of the pipe. In addition, the transfer in the circumferential direction on the inner surface of the pipe can be transmitted to the welded drive wheel 19, which is also attached. When the electric motor 17 is thereby driven, the drive wheel 19 rolls on the inner surface of the pipe, and the welding head 15 moves around the center of the pipe. In addition, depending on the gear ratio of the gear mechanism 18, the welding hole 1-15 is indicated by an arrow in Figure 1.
Even when the electric motor 17 is stopped and closed after turning in the direction of raising force, the welding throat I5 rotates in the direction of lowering force.
There is no A.

In addition, such circular movement of the throat 15 for welding is carried out by installing an annular rank concentrically on the inner surface of the pipe, and by moving the electric motor 17
This may be done by driving a pinion connected to the.

A cuppa shoe 11 is mounted on the inner surface of the tube, which is substantially the same in the circumferential direction as the mounting position of the driving wheel 19 of the welding head 15, along the inner surface of the tube. Kappa shoe 1
(2) slides on the inner surface of the pipe as the welding hem 1'15 moves.

At a position near the other end of the welding head 15 in the circumferential direction
As shown in the figure, the welding tip 21 is installed with the axis of the tip 21a located at its tip inclined by a predetermined angle α with respect to the normal line 29 of the inner surface of the tube. At the other end of the helenoid 15 in the pipe circumferential direction, there are set 1 holes at appropriate length intervals in the pipe circumferential direction so as to allow transfer on the grooved surface of the abutting part.
The pair of copying rollers 20 and 20 are taken. As shown in FIG. 2, the welding torch 21 has a shape curved toward the normal line 29, and there are wires 21b 4c3 inside.
j! ! It is inserted with a long protrusion.

The inclination angle α of the welding torches 1 and 2 and the distance % illa between the tip of the welding torch 2I (specifically, the tip of the welding torch 21) and the pipe inner surface are adjustable. As shown in FIG. 2, a guide rail 23 curved toward the drive wheel 19 from the center in the circumferential direction of the 7FI5 to the other end is connected to welding (1+-1). The center of curvature coincides with the tip of the wire 211].The guide rail 23 has a holder 24 that supports the welding torch 21 therein, and upper guide rollers 22a, 22a, The lower guide 1 is mounted so as to be sandwiched between the rollers 22b.The guide rollers 22a,
22a.

22b is movable along a guide roller 23, and by rolling the guide rollers 22a, 22a, 22b, the mounting position of the holder 24, that is, the inclination angle α of the welding 1 and the welding 21 is adjusted. can be adjusted.

This adjustment is performed by rotating the joint 25 installed at the opposite side of the pipe inner surface of the /8 joint 15, and connecting one end to this through the connecting part +, 426. This is done by threading the screw rod 28 which is screwed into the boulder 24, and moving the boulder 24 along the guide 1[--rule 23.6. Since the center of curvature of the gail 24 and the tip of the wire 21b coincide, the distance %lla of this 11il arrangement remains unchanged.

Next, the node of distance %ila will be explained. Welding of the guide rail 24 -) The full end of the center part of the FI5 in the tube circumferential direction is attached to the guide rail support member 40 (=J). Each time the threaded rod 4I is threaded, it can come into contact with and separate from the inner surface of the pipe, and by adjusting the feed amount, the distance 1ii1ia can be adjusted.

The copying roller 20.20 is driven by an electric motor 17 to move the welding head 15 around the inner surface of the pipe, that is, welding 1-.
The welding torch 2 accurately welds the grooved portion and forms a molten pool at the front end in the direction of the moving force of the copper shoe 11.

Next, the procedure for implementing the present invention will be explained in detail. The unwelded pipe 2 is suspended by a crane, the already welded pipe 1 and the core stand 1 are laid, and the pipe ends of both pipes 1 and 2 are butted against each other. Next, weld the two pipes by manual welding at appropriate locations within the groove of the butt opening, and temporarily attach the two pipes 4 times. Next, as described in 1-1, the lever blocks 4, 4 are tightened to tighten the lever blocks 4, 4, and the outer surface δ of the abutting part is fixed, and then a water pump is used to internally tighten the lever blocks 4, 3. Cooling water 7 is circulated.

Next, welding joint 1]5 is installed in the pipe, and the position in the circumferential direction of the inner surface of the pipe shown in Fig. 5 is shown in Table 1.
Perform welding according to the contact conditions. FIG. 5 is a schematic front view without showing the circumferential position of the inner surface of the tube at time d1, and since it is left-right and j-shaped, the stone side half is omitted. Table 1 shows the welding conditions (distance a, IIJt angle α, groove shape, welding voltage, welding current) when welding 1 and 21 are located at the final joint position in the pipe circumferential direction compared to the conventional method. This is a table showing the comparison. However, the welding conditions are the same for the left-right symmetrical positions in the tube circumferential direction, and the right half is omitted. The steel pipe to be welded has a diameter of 200 (1+ m) and a wall thickness of 20 mm.

(Tables 1 and 2) In the J method, the welding position was set to a distance of 1ilIla, and the inclination angle α was set to a value of W compared to the conventional method. Since the shape of the molten pool differs accordingly, it is necessary to change d and α, but as a result of repeated experiments, it has been found that the values shown in Table 1 are desirable. In addition, the groove angle was increased because
J to the root gear.

Now, will each welding position be welded under the above conditions?In reality, first, the operator positions the welding hole I'15, that is, the welding torch 21, at the 6.5 o'clock (6:30) position. Also, set the welding conditions at the relevant position as specified in Table 1, then drive the electric motor I7 and move the welding l-chi 21 in the direction of upward force in a circular direction. The person corrected the welding conditions and 11.5
Perform welding up to the current position. That is, welding is performed in the area shown by diagonal lines in FIG.

Considering that the operator makes such corrections, this welding machine can be called a semi-automatic welding machine, but it is equipped with a pipe circumferential position detector and a. By providing an actuator that changes α, welding can be substantially fully automated.

Next, welding 1--21 is placed at the 5.5 o'clock position, electric motor 7 is reversely driven, and welding 1 is started.
--Move 21 counterclockwise in the "1 ascending direction," 05
Perform welding up to the current position.

Here, between the 115 o'clock position and the 0.5 o'clock position, and 5
The reason why the area between the 85 o'clock position and the 6.5 o'clock position was excluded is because the torch 21 is curved as described above, so it was not possible to set an appropriate angle α when welding that part. It depends on the situation.

Note that by welding the above-mentioned welding position, the temporarily welded part in the above-mentioned groove is melted and embedded in the weld metal, so that the back of the smooth shape corresponding to the shape of the curved groove 36 is melted. Wave bee 1 is formed.

Next, remove the fixed leg and welding heno FI5 from inside the pipe,
Also, release the tightening of lever flocks 4, 4, and
Remove 3. Then, the inner and outer surfaces of the welded pipe 1 and the unwelded pipe are welded by hand between the 11.5 o'clock position and the 05 o'clock position O: 5.5 o'clock position and the 6.5 o'clock position. Welding with welded pipe 2 is completed.

[Su J Ka]

Next, the effects of the present invention will be explained with reference to Table 2 based on Examples. Table 2 shows the results obtained using the method of the present invention with a tube diameter of 2000. Already 79 joints with wall thickness 141-29. FIG. 2 is a table showing the results of imaging the welded portion and inspecting the finished quality using grade 3 X-ray film when unwelded pipes are subjected to /a welding. FIG.

Table 2 As shown in Table 2, when the method of the present invention was used, the passing rate of finishing quality was high, and good results were obtained.

In addition, when using the method of the present invention, the alignment work can be performed quickly and the time required for bead polishing can be shortened, so that the work efficiency is about 14% higher than when using the conventional method.
It was confirmed that it was possible to achieve a % improvement of -○.

In the case of the 7+ method of the present invention as described above, a curved groove that does not form a rough-shaped Uranami bead is provided, and a copper stopper that can be cooled by water can be attached and detached to the outer surface of the tube end abutment part. Since the tube end abutting M portion is welded according to the welding conditions determined in advance through experiments, efficient welding can be performed and a good welded finish quality can be obtained.

In addition, in the case of several dozen embodiments, the root gap is set to substantially 0, the welded pipe and the unwelded pipe are butted against each other, and the grooves of this butted portion are temporarily welded to form a joint between the two pipes. Since the two pipes are connected in an aligned state, it is easy to position both pipes in the axial direction, and it is possible to easily position the two pipes in the axial direction.
The present invention has excellent effects such as being able to quickly perform centering work without the need for horse-mounting, and further improving the efficiency of the entire welding work, resulting in a significant reduction in varnish. play.

[Brief explanation of the drawing]

Figure 1 is a stop view showing the implementation state of the present invention method, Figure 2 is an enlarged view of the welding area, Figure 3 is an enlarged cross-sectional view of the welding metal, Figure 4 is l 41 is a schematic front view showing the joining position; FIG. 5 is a partial vertical sectional view showing the state of implementation of the six conventional methods; FIG.
It is a partial cross-sectional view.

Claims (1)

[Claims] 1. A welding torch that abuts the ends of large-diameter steel pipes against each other, attaches a stopper to the outer surface of the abutted portion, and is movable around the inner surface of the abutment. In this method, two large diameter steel pipes are aligned and butted together, temporarily welded, and a groove for a uranami bead is formed on the pipe side.
Further, a water-coolable copper stopper is removably fixed to the abutting portion, and the distance of the welding torch tip to the inner surface of the pipe is adjusted depending on the circumferential position of the abutting portion. An automatic welding method characterized by welding abutted portions while changing the inclination angle in the circumferential direction of the tube with respect to the normal to the inner surface of the tube. 2. The automatic welding method according to claim 1, wherein the root gap of the abutted portion is substantially zero.