JP2804399B2 - Spiral steel pipe inner surface welding method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a profiling method for welding spiral joints to form spiral steel pipes after spirally forming a steel strip and manufacturing a spiral steel pipe.

[0002]

2. Description of the Related Art As a method of manufacturing a welded steel pipe by forming a steel strip into a spiral shape and then continuously welding joints thereof, a method of welding an outer surface after welding an inner surface by conventional submerged welding is used. Instead, a composite welding method in which a formed steel sheet is welded by resistance welding, a seam of the outer surface is welded by submerged welding, and then the inner surface is welded is disclosed in JP-A-59-49.
No. 91 was proposed.

[0003] The adoption of this composite welding method enables high-density and high-speed heating by electric resistance welding and a large amount of heat input, so that the majority can be welded and the submerged welding which enables high-speed core feed can be performed. Is almost twice as fast as before, and is very promising as an efficient method for manufacturing a spiral steel pipe.

[0004] However, for welding the inner surface, for example, Japanese Patent Application Laid-Open Nos. 50-57933 and 53-761.
As disclosed in, for example, Japanese Patent Publication No. 41, an operator recognizes a shift between a welding torch reference needle and an inner surface seam by a monitoring camera installed on the inner surface of the pipe,
The displacement was manually corrected.

[0005]

However, since the shape of the joint is unclear and the surveillance camera is located on the inner surface of the pipe, the joint is not sufficiently illuminated. Since the needle is displaced and the welding line is displaced, and because the welding torch is manually adjusted, the operation that can follow the seam fluctuation cannot be performed, not only the work efficiency is low, but also the problem that the seam dislocation defect occurs. was there.

An object of the present invention is to form a steel strip into a spiral shape,
An object of the present invention is to provide a method for accurately performing inner surface welding when manufacturing a spiral steel pipe by welding the joint.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an outer surface is first welded to a joint of steel sheets after a steel strip is formed into a spiral shape,
Next, in a method of manufacturing a spiral steel pipe for performing inner surface welding, the inner surface welding is performed using the moving amount of the outer surface welding torch as a reference of the inner surface welding torch.

As a device for carrying out the present invention, a device for detecting a moving amount of a driving device used for moving an outer surface welding torch, and a moving amount detected by the detecting device for moving the inner surface welding torch. The control device may be a device provided with a control device serving as a control input amount to the device.

[0009]

[Action] Since the outer surface welds the outer surface of the pipe, the operator visually matches the welding torch with the seam, and the outer surface welding torch detects the change of the seam. Is used as a seam position signal. In other words, the displacement of the welding torch during external welding is directly used as a control factor for the displacement of the internal welding torch. , As long as the positioning of the welding torch for external welding is done correctly,
Internal welding can be performed automatically and reliably.

[0010]

FIG. 1 shows an outline of a facility to which the present invention is applied.

In FIG. 1, reference numeral 1 denotes a series-heating type submerged arc outer surface welding torch for welding the outer surface of a steel pipe formed into a spiral shape, and 2 denotes a joint B of a steel sheet A which is continuously formed. Are visually confirmed, and a drive motor for aligning the outer surface welding torch 1 with the joint B is shown. Reference numeral 3 denotes a torch for welding the inner surface of the submerged arc of the series heating type, and 4 denotes a moving table for aligning the inner welding torch 3 with the inner surface of the steel plate joint B. 5 is the operating rod 6
The operation rod 6 attached is moved in the direction of the arrow so that the inner surface welding torch 3 attached to the end thereof can be aligned with the steel sheet joint B. Reference numeral 7 denotes a detector for detecting the amount of movement of the outer surface welding torch 1, and reference numeral 8 denotes a control device for converting and controlling the amount of movement from the detector 7 to the amount of movement of the inner surface welding torch 3.

FIG. 2 shows the principle of operation. Referring to FIG. 1 and FIG. 1, when the joint B of the steel sheet S continuously formed into a spiral shape moves from a predetermined position, the operator visually observes a deviation between the joint and the outer surface welding torch 1. ,
Drive motor 2 of torch 1 for external welding by manual operation
To correct the positional deviation. The amount of movement of the outer surface welding torch 1 at this time is measured by the detector 7, and based on the amount of movement, the control device 8 performs position feedback control of the inner surface welding torch 3. The moving amount of the inner surface welding torch 3 is set in the control device 8 in accordance with the normal movement of the formed steel pipe. When the outer surface welding torch 1 moves, the moving amount is transmitted to the controller 8. The input device is moved by an amount adjusted by the input by the driving device 5.

[0013] The seam deviation amount in the conventional manual copying method is ±
While this was about 3.3 mm, the use of this copying method reduced it to ± 1.05 mm, and it was possible to obtain about twice the copying accuracy.

[0014]

According to the present invention, the following effects can be obtained.

(1) In manufacturing a spiral steel pipe, a copying system of a welding torch can be constructed, and a high-precision copying welding can be performed, so that a seam detachment defect can be eliminated.

(2) The equipment can be automated by adopting a relatively simple apparatus in which a conventional welding equipment is simply provided with a movement detector.

(3) Since the movement amount of the outer surface welding torch by direct visual observation is used as a control standard, there is no occurrence of displacement.

(4) Since the displacement detector is attached to the outer surface of the pipe, it is not adversely affected by heat and welding current noise, so that highly reliable equipment can be provided.

(5) Since automatic seam copying eliminates the need for an inner surface welding operator, labor can be saved.

[Brief description of the drawings]

FIG. 1 shows an outline of an apparatus according to an embodiment of the present invention.

FIG. 2 shows the actuation system of the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torch for outer surface welding 2 Drive motor 3 Torch for inner surface welding 4 Moving table 5 Drive device 6 Operation rod 7 Detector 8 Control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-215273 (JP, A) JP-A-52-63139 (JP, A) JP-A-60-72673 (JP, A) JP-A 52-63273 52858 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23K 9/032 B21C 37/12 B23K 9/127 B23K 9/02 B23K 9/18

Claims (2)

(57) [Claims] 1. A method for manufacturing a spiral steel pipe, in which an outer surface is first welded and then an inner surface is welded at a joint of steel plates after a steel strip is formed into a spiral shape, the displacement of the outer surface welding torch is determined by the inner surface welding torch. Spiral pipe inner surface welding method that performs inner surface welding as a reference for profiling. 2. A device for detecting the amount of movement of a drive device used for moving the outer surface welding torch, and the amount of movement detected by the detector is used as a control input amount to a device for driving and moving the inner surface welding torch. Spiral steel pipe inner surface welding device equipped with a control device.