JPH07284927A - Apparatus for welding inner surface of spiral steel tube - Google Patents

Abstract

PURPOSE:To provide a welding apparatus for inner surface of a spiral steel tube, in which the adjustment of plural welding torch positions can remotely be operated and a device for feeding a wire and a device for controlling the position and the angle of the welding torch are arranged at the comparatively easy position for executing the maintenance and the checking in the rear part and the operability is further improved and the automation can be executed. CONSTITUTION:This welding apparatus is provided with an intermediate supporting frame 11, a welding head mounting frame 12 provided with plural sets of the welding torches arranged so as to be possible to move to the front and rear direction at the front part of the intermediate supporting frame 11 and a rear part frame 13 arranged so as to be possible to move to the front and rear direction at the rear part of the intermediate supporting frame 11. Further, this welding apparatus is provided with connecting rods for connecting the rear part frame 13 and the welding head mounting frame 12 and an advanced/retreated driving means 37 for shifting the welding head mounting frame 12 and the rear part frame 13 connected with the connecting rods in the front and rear direction while using the intermediate supporting frame 11 as the reference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral steel pipe inner surface welding apparatus capable of quickly responding to a size change at the time of manufacturing a spiral steel pipe, and also capable of finely adjusting each welding torch remotely.

[0002]

2. Description of the Related Art When changing the size of a steel pipe in a spiral steel pipe manufacturing facility, as described in Japanese Patent Publication No. 63-58674, a spiral angle of a welding nozzle row composed of welding nozzles provided at the tip of a plurality of welding torches. It is necessary to adjust the longitudinal position with respect to the pipe axis and the longitudinal position of the weld seam. Further, in the above-mentioned publication, a welding head equipped with a plurality of sets of welding units composed of a welding nozzle and a core wire feeding device which are moved in the front-rear direction with respect to a pipe axis is supported by a telescopic beam which is telescopically driven by a telescopic drive device. An internal welding device for spiral steel pipes that moves in a vertical direction has been proposed.

[0003]

However, in the inner surface welding apparatus described in the above publication, the electric cable, the welding wire guide, and the welding power feeding cable of each drive motor attached to the holding portion are extremely moved during movement. Bends,
There are problems such as being entangled and getting caught between the welding head and the telescopic beam.Therefore, when moving the welding head, the operator should always monitor and bend the electric cables and the welding wire guide. While making corrections to
The welding head must be moved, which makes automatic operation difficult.

In addition, when the spiral angle of the welding nozzle is changed, the angle of only the linear welding torch is fixed while the welding core wire supplying device is fixed, so that the core wire guide between the core wire supplying device and the welding nozzle is twisted and the linearity is changed. Is lost, and there is a problem that welding core wire feeding is not stable. The diameter of the welding power feeding cable connected to feed power to the welding torch is about 40 mm, and when the length is short, there is no flexibility and resistance is great, even if the angle of the welding torch is changed. Since the welding torch often did not move, we had to intervene manually. Furthermore, since multiple welding torches are held together on the rotary base for changing the spiral angle, even if the welding torch forming angle is adjusted, the position in the longitudinal direction of the pipe axis delicately shifts, and again after adjusting the forming angle. It was necessary to adjust the position in the longitudinal direction of the tube axis.

In addition, since the wire feeding device and the like are installed in the steel pipe, it takes a lot of time for adjustment and a precise welding torch because the working environment is poor in a narrow space for the operator. It was difficult to adjust the position.
Due to such a problem, the operating rate of the steel pipe production line was poor, and it was necessary to secure workers for adjustment.

The present invention has been made in view of the above circumstances. A plurality of welding torch position adjustments can be remotely controlled, and a wire feeding device and a device for controlling the position and angle of the welding torch are provided at the rear portion. It is an object of the present invention to provide a spiral steel pipe inner surface welding device which can be arranged in a place where maintenance and inspection can be easily performed, which has improved operability and can be automated.

[0007]

A method according to the above-mentioned object.
The inner surface welding device of the spiral steel pipe described, an intermediate support frame, a welding head mounting frame provided with a plurality of sets of welding torches provided in the front part of the intermediate support frame so as to be movable back and forth, and in the rear part of the intermediate support frame. A rear frame movably arranged back and forth, a connecting rod for connecting the rear frame and the welding head mounting frame, the welding head mounting frame and the rear frame connected by the connecting rod as a reference to the intermediate support frame. And a forward / backward drive means for moving in the front-rear direction as the welding torch guide pipes extended to the rear frame are connected and fixed to the respective welding torches, and the welding torch guide pipes are used to connect the welding torch guide pipes. Power is supplied to the welding torch and a welding wire supply device paired with the welding torch is connected to the rear flap. Provided over arm is configured so as to supply the welding wire to the welding torch through the welding torch guide pipe.

A spiral steel pipe inner surface welding device according to a second aspect is the device according to the first aspect, wherein the welding head mounting frame is provided with a clamping device and an elevating device for the welding torch, and the connecting rod is hollow. The shaft serves as a shaft, and the power supply cables for the clamp device and the lifting device are wired inside the hollow shaft. The inner surface welding apparatus for a spiral steel pipe according to claim 3 is the apparatus according to claim 1 or 2, wherein a dome-shaped cover connected to the intermediate support frame is disposed on an upper portion of the welding head mounting frame, and the cover is provided. The guide member of the welding head mounting frame is provided on the side portion of.

An inner surface welding apparatus for a spiral steel pipe according to a fourth aspect is the apparatus according to any one of the first to third aspects, wherein each of the welding torches and the guide pipe for the welding torch connected to the welding torch are the above-mentioned. When the clamp device is opened, it can be rotated and moved back and forth, a torch tilt angle adjusting device for rotating the welding torch guide pipe is provided on the rear frame, and the rear frame is provided with a torch tilt adjusting device. A torch longitudinal movement adjusting device for adjusting the relative position in the longitudinal direction is provided and configured. And the inner surface welding device of the spiral steel pipe according to claim 5 is
The apparatus according to any one of claims 1 to 4, wherein the connecting rod and the welding torch guide pipe are configured to pass through the intermediate support frame in a freely movable manner in the front-rear direction.

[0010]

In the inner surface welding apparatus for spiral steel pipes according to the first to fifth aspects, the welding head mounting frame and the rear frame are provided in the front and rear of the intermediate supporting frame so as to be movable in the front-rear direction, and these are connected by a connecting rod to advance and retract. Since the driving means can be moved back and forth, the welding torch mounted on the welding head mounting frame is moved back and forth by operating the advancing / retreating driving means, whereby the entire welding position can be adjusted. Therefore, if necessary, the advancing / retreating drive means can be operated to cause the nozzle at the tip of the welding torch to follow the welding seam.

Further, since the welding torch guide pipe and the rear frame are integrated, the necessary device for driving the welding torch can be mounted on the rear frame. Since each welding torch part provided on the welding head mounting frame is connected and fixed to the guide pipe for the welding torch extended to the rear frame, the welding wire feeding device is arranged on the rear frame, and the welding torch is arranged. The welding wire can be supplied from the rear part of the guide pipe. In this case, since the welding wire supply device is provided on the rear frame, maintenance and inspection is facilitated, and further the welding unit on the front side is simplified.

Since power is supplied to the welding torch through the welding torch guide pipe, a special power supply cable is eliminated, and the welding torch guide pipe also serves as a wire guide for feeding the welding wire. Therefore, the device is simplified. Particularly, in the inner surface welding apparatus for a spiral steel pipe according to the second aspect, since the welding head mounting frame is provided with the welding torch lifting device, the welding torch can be adjusted up and down and the welding torch clamping device can be provided. Since it is provided, the welding torch can be fixed to the welding head mounting frame during welding. Since these power supply cables are wired inside the hollow connecting rod, there is no need for a special wiring duct or the like, the device is simplified, and the device is downsized and has a small diameter. It becomes easy to deal with.

In the inner surface welding apparatus for the spiral steel pipe according to the third aspect, since the dome-shaped cover is provided on the upper portion of the welding head mounting frame, the scale enters the welding unit including the welding torch from the upper portion. It is possible to prevent the damage of the welding unit due to the penetration of the arc from the outer surface welding and the collision of the strip with the welding unit. Since the guide member of the welding head mounting frame is provided on the side portion of the cover, the welding head mounting frame can be reliably moved in the front-rear direction by using the guide member, and the cover is used as a support member for the guide member. Therefore, the structure can be simplified.

In the inner surface welding device for a spiral steel pipe according to the fourth aspect, since the torch tilt angle adjusting device for rotating the guide pipe for the welding torch is provided in the rear frame, it is attached to the front side of the guide pipe for the welding torch. It is possible to adjust the tilt angle of the welding torch that is used. Also,
Since the rear frame is provided with a torch longitudinal adjustment device that determines the relative position of each welding torch in the front-rear direction, the relative position in the front-rear direction of a plurality of devices should be performed by the device provided in the rear frame. You can Furthermore,
Since these are provided on the rear frame, maintenance and inspection becomes easy.

[0015]

Embodiments of the present invention will now be described with reference to the accompanying drawings to provide an understanding of the present invention. 1 is a perspective view of an inner surface welding apparatus for a spiral steel pipe according to an embodiment of the present invention, FIG. 2 is a schematic explanatory view thereof, and FIGS. 3 to 9 are partial perspective views thereof.

As shown in FIGS. 1 to 8, an inner surface welding device 10 for a spiral steel pipe according to an embodiment of the present invention is provided at a central intermediate support frame 11 and before and after the intermediate support frame 11. A welding head mounting frame 12 and a rear frame 13 and a connecting rod 14 for connecting them;
15, a welding unit 19 including first to third welding torches 16 to 18 mounted on the welding head mounting frame 12, an accessory device thereof, and the first to the first mounted on the rear frame 13. 3 welding torch 16-18
Torch tilt adjusting devices 20 to 22 and torch longitudinal movement adjusting devices 23 and 24 of the first and third welding torches 16 and 18.
And have. These will be described in detail below.

The intermediate support frame 11 is shown in FIGS.
As shown in FIG. 3, the auxiliary equipment is attached to the spiral steel pipe forming equipment and is necessary for forming the spiral steel pipe 25 (for example, the power cylinder 2 for adjusting the forming angle).
6, L side reduction rod 2 with rollers attached to the bottom
7 and R side reduction rod 28, reduction balance rod 29,
The servo valve stand 30 for inner surface copying is provided. Then, a support frame 32 having the copy guides 31 of the rear frame 13 on both sides is fixed to the rear part of the intermediate support frame 11, and a dome-shaped (semicircular cross-section) cover 33 covering the welding unit 19 is provided on the front part. Is provided. It should be noted that FIG. 1 shows a state in which the cover 33 projects from the dome-shaped cover 33, and maintenance is performed in this state.

As shown in FIGS. 3 and 4, the cover 33 is formed.
Guide rails 34 and 35 are provided on both inner sides of the welding head mounting frame 12 by the guide rails 34 and 35 so as to be movable back and forth via upper and lower guide rollers 34a. As shown in FIG. 2, the intermediate support frame 11 is provided with two through holes 36, and the rear frame 13 is attached to the copying guide 31 so as to be movable back and forth and the welding head mounting frame 12.
Two connecting rods 14 and 15 for connecting and are loosely fitted in the through hole 36. In addition, the intermediate support frame 11
A hydraulic cylinder 37, which is an example of a forward / backward drive means, is attached to the hydraulic cylinder 3, and the end of the forward / backward rod 38 of the hydraulic cylinder 37 is fixed to the rear frame 13.
By expanding and contracting 7, the front and rear welding head mounting frames 12 and the rear frame 13 simultaneously move back and forth with respect to the intermediate support frame 11.

As shown in FIGS. 3 and 4, the welding head mounting frame 12 has first to third welding torches 16 to 1.
8 is provided, a flux supply device 39 is provided on the front side of the first welding torch 16 and a third welding torch 18 is provided.
Is provided with a hopper 40 for collecting the used flux on the back side thereof, and during the welding (submerged arc welding), welding is performed while supplying the flux from the flux supply device 39, and the powder on which the hopper 40 for collecting the back side remains The flux is collected by vacuum suction.
The pipes 41 and 42 connected to the flak supply device 39 and the flux recovery hopper 40 are piped to the rear frame 13 through the side portions of the intermediate support frame 11 and connected to a flux transfer means and a recovery means (not shown). Has been done.

Then, the first to third welding torches 16
Welding torch guide pipes 43-45 at the base ends of
Are connected via conductive joints 46 to 48, and the welding torch guide pipes 43 to 45 penetrate through the intermediate support frame 11 with a sufficient gap, and the welding of the torch guide pipes 43 to 45 of the rear frame 13 shown in FIG. The welding wire feeders 49 to 51 are extended in an electrically insulated state, act as guide pipes for a plurality of or single welding wires, and also serve as conductors for supplying a welding current to the respective welding torches 16 to 18. ing. Since the welding torch guide pipes 43 to 45 are applied with a welding voltage during welding, it is preferable to provide an insulating cover for the exposed portion for application.

Guide pipes 43 to 45 for the welding torch
Clamping devices 52 are provided at the tip of each. The clamp device 52 has a tapered upper wedge 53 and a lower wedge 54 which slide as shown in FIG. 5, and the hydraulic cylinder 55 for clamping moves the lower wedge 54 forward and backward to press the upper wedge 53 to the upper part. Each of the welding torch guide pipes 43 to 45 insulated and held by the insulating cylinder 56 is independently clamped, and the first to third welding torches 16 attached to the front ends of the welding torch guide pipes 43 to 45. The rotation of 18 to 18 and the forward / backward movement are prevented.

The guide pipe 43 for the welding torch is also provided.
The clamp devices 52 to 45 are mounted on the common base plate 57, and a tapered upper and lower wedge 58 for sliding and a lower wedge 59 for ascending and descending are provided on the lower part of the common base plate 57. A male screw 60 is screwed into the lower wedge 59, and the male screw 60 is operated by a drive motor 61 to move the lower wedge 59 for lifting up and down.
The clamp device 52 mounted on the common base plate 57 is moved up and down to simultaneously move up and down the welding torches 16 to 18, thereby forming a welding torch lifting device 62a. The lower wedge 59 for raising and lowering is provided with a striker 62 as a limit switch, and the upper and lower limits of the welding torches 16 to 18 are determined by limit switches (not shown) provided at the front and rear.

As shown in FIGS. 6-8, the rear frame 1
Torch tilt angle adjusting device 20 (21, 21,
22 is also the same), a tilting arm 63 for holding the welding torch guide pipe 43, and a pin 65 on a slide piece 64 provided at the tip of the tilting arm 63 so as to be extendable and contractible.
And an electric worm jack 66 that is rotatably connected via the. Since the first and third torch tilt angle adjusting devices 20 and 22 are separated from each other, the second torch tilt angle adjusting device 21 is shown in FIG. 6 and FIG. 8 at the same position on the rear frame 13 as shown in FIG. Rear frame 1 as shown
It is attached to the rear part of 3 and has the same basic configuration. And each torch tilt angle adjusting device 20-
Welding torch guide pipes 43-4 by driving each of the 22 electric worm jacks 66 separately.
First to third welding torches 1 mounted on the front side of
6 to 18 can be independently tilted.

Welding wire feeding devices 49 to 51 are attached to the rear portions of the torch tilt angle adjusting devices 20 to 22, respectively. The welding wire feeding devices 49 to 51 are fitted with a welding wire (in the case of a single wire). ) Or a pair of upper and lower rollers (in the case of a plurality of wires) having a pair of grooves, and variable speed motors 49a to 51a for rotationally driving one or both of the rollers and are not shown at a constant controlled speed. The welding wire is taken out from the wire supply source and supplied to the first to third welding torches 16 to 18 through the welding torch guide pipes 43 to 45. The welding wire supply devices 49 to 51 and the torch tilt angle adjustment devices 20 to 22 are independent pedestals 6 respectively.
7 to 69, the mount 68 is mounted on the rear frame 1
3 is fixed via an insulating member to the pedestal 6
7, 69 are attached to the moving bases 70, 71 via insulating members, and the moving bases 70, 71 are attached to the rear frame 13 movably in the front-rear direction via guide members arranged on both sides. There is.

The lower part of the moving bases 70 and 71 is shown in FIG.
Ball screw nut 72
Are attached respectively, and the ball screw nut 7
2 is screwed into a ball screw 74 having a deceleration motor 73 attached to the base end thereof, and by rotating each deceleration motor 73, the moving bases 70, 71 move forward and backward,
This results in the first and third welding torches 1
The torch longitudinal movement adjusting devices 23 and 24 are constituted by the torch longitudinal movements 6 and 18.

A gate-shaped support member 74a is provided on the front portion of the rear frame 13, and connectors 75 to 77 for supplying welding current are provided on the support member 74a in an insulated state. Further, rotary joints 81 to 83 are provided on the front cylindrical portions 78 to 80 of the connectors 75 to 77, and the rotary joints 81 to 83 and the welding torch guide pipe 43 to.
45 are connected to each other by air-cooling type secondary cables 84 to 86 made of a slightly long strand wire.
The rotary joints 81 to 83 are torch tilt angle adjusting devices 20 to 2
This is because when the welding torch guide pipes 43 to 45 are twisted by 2, the secondary cables 84 to 86 are prevented from rotating and applying an unreasonable force. A rotary joint may be provided at the connecting portion of the welding torch guide pipes 43 to 45. In this case, fixed wiring may be used for the secondary cable. In the figure, 87 is a relay terminal box, 88 is a welding power source, and 89 is an inner surface welded portion of the spiral steel pipe.

Therefore, the inner surface welding apparatus 10 for the spiral steel pipe has the first to third welding torches 16 to 18, and is suitable for changing the size of the spiral steel pipe to be manufactured.
When moving all three welding torches 16-18, the hydraulic cylinder 37 is expanded / contracted and the 1st, 3rd welding torches 16 and 18 are made on the basis of the 2nd welding torch 17.
In the case of individually advancing and retreating, the clamping device 52 is released and the torch longitudinal movement adjusting devices 23 and 24 are operated. Then, the first to third welding torches 16
When elevating and lowering the whole of .about.18, the elevating device 62a is driven. Thereby, the distance between the nozzles 16a to 18a of the welding torches 16 to 18 and the welded material can be changed.

Further, the first to third welding torches 16 to 18
When changing the angle of the torch tilt angle adjusting devices 20 to 22, the clamp device 52 is released. By the above operation, the first to third welding torches 16 are produced according to the size of the spiral steel pipe.
Since 18 can be changed, a rotary encoder is attached to each motor, and a linear sensor (moving distance meter) is provided in a linear moving portion (for example, a portion driven by the hydraulic cylinder 37) to adjust the size of the steel pipe. In addition, each operation procedure and moving position are registered in advance, and the whole can be automatically controlled in association with the control of the spiral steel pipe manufacturing equipment.

In the above embodiment, the number of welding torches was three, but the present invention is applicable even if the number of welding torches is two or four or more. Further, the welding method was submerged arc welding using flacks, but other arc welding methods may be used, and in this case, the shielding gas may be supplied by a separate pipe, or the welding torch. A guide pipe for use may be used. Further, although the welding torch elevating device is adapted to elevate and lower all the welding torches at the same time, they may be individually moved.

[0030]

According to the inner surface welding apparatus of the spiral steel pipe of the present invention, the welding head mounting frame and the rear frame of the intermediate support frame can be moved back and forth by the advancing and retracting drive means. The welding torch mounted on the frame can be moved back and forth to adjust the overall welding position. Therefore, if necessary, the advancing / retreating drive means can be operated to cause the entire welding torch to follow the welding seam. Further, since the welding torch guide pipe and the rear frame are connected by a connecting rod to be integrated, a necessary device for driving the welding torch can be mounted also on the rear frame. Maintenance is extremely easy and the wiring from the front welding head mounting frame to the rear frame for power and signal transmission is reduced.
Further, since the welding torch at the front part and the welding wire supply device at the rear part are connected by the guide pipe for the welding torch, it is easy to guide the wire, and the welding torch is utilized by using the guide pipe for the welding torch. Because you can supply power,
Wiring with a thick welding cable as in the past is no longer necessary. Particularly, in the inner surface welding apparatus for a spiral steel pipe according to the second aspect, since the welding head mounting frame is provided with the welding torch lifting device, the welding torch can be adjusted up and down and the welding torch clamping device can be provided. Since it is provided, the welding torch can be fixed during welding, which stabilizes the welding operation. Also, since these power supply cables are wired inside the connecting rod, there is no need for a special wiring duct or the like, the device is simplified, and it is possible to cope with the small diameter size of the inner surface welding device. It will be easy. In the inner surface welding apparatus for a spiral steel pipe according to claim 3, since the welding head mounting frame has a dome-shaped cover on the upper portion, the welding unit is prevented from entering scale from the upper portion, and the arc from the outer surface welding is prevented. It is possible to prevent damage to the welding unit due to penetration and prevent the strip from colliding with the welding unit, and protect the device. In the inner surface welding apparatus for a spiral steel pipe according to claim 4, since the torch tilt angle adjusting device and the torch longitudinal movement adjusting device for rotating the welding torch guide pipe are provided in the rear frame, the inclination of the plurality of torches, Further, since the front and rear positions can be automatically changed, and since these devices are provided on the rear frame, maintenance and inspection are extremely easy.
In the inner surface welding device for a spiral steel pipe according to claim 5, since the connecting rod and the guide pipe for the welding torch penetrate through the intermediate support frame, it is possible to keep this straight, and further the entire device is made compact. Can be incorporated inside the spiral steel pipe to be manufactured.

[Brief description of drawings]

FIG. 1 is a perspective view of an inner surface welding apparatus for a spiral steel pipe according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory view of the same.

FIG. 3 is a partial perspective view of the same.

FIG. 4 is a partial perspective view of the same.

FIG. 5 is a partial perspective view of the same.

FIG. 6 is a partial perspective view of the same.

FIG. 7 is a partial perspective view of the same.

FIG. 8 is a partial perspective view of the same.

FIG. 9 is a partial perspective view of the same.

[Explanation of symbols]

 10 Inner Surface Welding Device of Spiral Steel Pipe 11 Intermediate Support Frame 12 Weld Head Mounting Frame 13 Rear Frame 14 Connecting Rod 15 Connecting Rod 16 First Welding Torch 16a Nozzle 17 Second Welding Torch 17a Nozzle 18 Third Welding Torch 18a Nozzle 19 Welding unit 20 Torch tilt angle adjustment device 21 Torch tilt angle adjustment device 22 Torch tilt angle adjustment device 23 Torch longitudinal movement adjustment device 24 Torch longitudinal movement adjustment device 25 Spiral steel pipe 26 Forming angle adjustment power thinner 27 L side reduction rod 28 R side reduction rod 29 Reduction Balance Rod 30 Servo Valve Stand for Inner Surface Copying 31 Copying Guide 32 Support Frame 33 Cover 34 Guide Rail 34a Guide Roller 35 Guide Rail 36 Through Hole 37 Hydraulic Cylinder 38 Forward / Reverse Rod 9 Flux supply device 40 Recovery hopper 41 Pipe 42 Pipe 43 Welding torch guide pipe 44 Welding torch guide pipe 45 Welding torch guide pipe 46 Conductive joint 47 Conductive joint 48 Conductive joint 49 Welding wire feeder 49a Variable speed motor 50 Welding Wire supply device 50a Variable speed motor 51 Welding wire supply device 51a Variable speed motor 52 Clamping device 53 Upper wedge 54 Lower wedge 55 Clamping hydraulic cylinder 56 Insulating cylinder 57 Common base plate 58 Elevating upper wedge 59 Elevating lower wedge 60 Male screw 61 Drive motor 62 Striker 62a Lifting device 63 Tilt arm 64 Sliding top 65 Pin 66 Electric warm jack 67 Frame 68 Frame 69 Frame 70 Moving base 71 Moving base 72 Baud Screw nut 73 Reduction motor 74 Ball screw 74a Support member 75 Connector 76 Connector 77 Connector 78 Cylindrical part 79 Cylindrical part 80 Cylindrical part 81 Rotating joint 82 Rotating joint 83 Rotating joint 84 Secondary cable 85 Secondary cable 86 Secondary cable 87 Relay terminal Box 88 Welding power source 89 Internal weld

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shizuo Kohinata 20-1 Shintomi, Futtsu-shi, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Yoshihiro Sakagami 1 Kimitsu, Kimitsu-shi, Chiba New Nippon Steel Stock Company Kimitsu Works

Claims (5)

[Claims] 1. An intermediate support frame, a welding head mounting frame provided in a front portion of the intermediate support frame so as to be movable back and forth and having a plurality of sets of welding torches, and a rearwardly movable portion arranged in a rear portion of the intermediate support frame. Rear frame, a connecting rod connecting the rear frame and the welding head mounting frame, and the welding head mounting frame and the rear frame connected by the connecting rod are moved in the front-rear direction with reference to the intermediate support frame. Advance / retreat drive means for connecting and fixing the welding torch guide pipes extended to the rear frame to the respective welding torches, and supplying power to the welding torches via the respective welding torch guide pipes. Along with the welding torch, a welding wire supply device, which is paired with the welding torch, is provided on the rear frame, Inner surface welding apparatus spiral steel pipe and supplying a welding wire to the welding torch through the switch guide pipe. 2. The welding head mounting frame is provided with a clamping device and a lifting device for the welding torch, the connecting rod is a hollow shaft, and the power of the clamping device and the lifting device is inside the hollow shaft. The inner surface welding apparatus for a spiral steel pipe according to claim 1, wherein a supply cable is wired. 3. On the upper part of the welding head mounting frame,
The inner surface welding of the spiral steel pipe according to claim 1 or 2, wherein a dome-shaped cover connected to the intermediate support frame is arranged, and a guide member of the welding head mounting frame is provided on a side portion of the cover. apparatus. 4. The welding torch and the welding torch guide pipe connected to the welding torch are rotatable and movable back and forth when the clamp device is opened, and the welding torch guide pipe is rotated around the rear frame. A torch tilt angle adjusting device for moving is provided, and further, a torch longitudinal movement adjusting device for adjusting relative positions of the respective welding torches in the longitudinal direction is provided on the rear frame.
An inner surface welding apparatus for a spiral steel pipe according to any one of 3 to 3. 5. The inner surface welding device for a spiral steel pipe according to claim 1, wherein the connecting rod and the welding torch guide pipe pass through the intermediate support frame so as to freely move back and forth.