JPH01289572A - Welding equipment for clad steel pipe - Google Patents

Abstract

PURPOSE:To perform cladding by welding with high efficiency and high accuracy by allowing a welding boom on which a clad steel pipe and plural TIG torches are arranged in series to approach and feeding hot wires to be supplied to the TIG torches and carrying a plus DC current or AC current thereto to perform welding. CONSTITUTION:A pipe 1 which is material to be welded is mounted on a carriage 2 and moved in the (a) direction shown by an arrow in the figure at the constant speed by a driving device 23. The welding boom 3 in opposition to the pipe 1 advances in the pipe 1. A first TIG torch 5 and an arch are generated on a tab plate of the pipe 1 end and the hot wires 11 are fed at the constant rate to perform hot wire TIG welding. A welding parameter is controlled by centralized control with a control panel 22. In accordance with the advance of the welding boom 3, second and third TIG torches and arches are generated in order to perform hot wire TIG welding. By this method, four-layer cladding by welding is performed by one run. By this method, the interior and exterior of the title clad steel pipe can be subjected to cladding by welding with high efficiency and high accuracy.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a welding device for clad steel pipes, particularly a welding device that can perform overlay welding of the inner surface of a high-alloy clad steel pipe in the longitudinal direction with high efficiency and high precision. It is related to.

[Prior Art] For example, as a welding method for UOE steel pipes, multi-electrode submerged arc welding is widely used for both inner surface welding and outer surface welding. Also in the case of high-alloy clad steel pipes, the steel sections are first welded from the inside and then from the outside by multi-electrode submerged arc welding. As another method, multi-electrode MIG welding has been used in some high-grade solid pipes, but it has not been used much recently due to problems such as the magnetic arc blowing phenomenon. For overlay welding of cladding materials, plasma welding, TIG welding, and MIG welding are used for small-scale items such as pressure vessels. but,
These welding methods have never been used on pipelines for high-alloy clad steel pipes made by the UOE method, and of course, overlay welding machines for the inner cladding portion have not yet been put into practical use.

[Problems to be Solved by the Invention] The requirements for internal overlay welding of high-alloy clad steel pipes manufactured by the UOE process are as follows.

(1) Applicable pipe size Minimum pipe diameter 16'φ (406 Dragonφ) Minimum length 12m (2) From the viewpoint of welding quality and corrosion resistance, the bead surface must be smooth and free of defects such as bits, slag entrainment, and cracks. Since the weld metal is diluted by the base metal, multilayer welding is desirable in consideration of stabilizing the alloy components in the overlay.

(3) Reliability of welding Many high-alloy clad steel pipes have small diameters, and repair after welding is often physically impossible and technically very difficult. If a welding defect occurs in the middle of a pipe, the product becomes unusable and the expensive pipe becomes ruined. Therefore, much higher reliability is required compared to normal welding.

(4) Welding efficiency If it is not possible to weld in a short time due to the balance with other processes,
The waiting time will be longer and the manufacturing cost will increase significantly.

From the perspective of welding methods that allow overlay welding, TIG welding, hot wire TIG welding, plasma welding, MIG
A possible method is welding. However, in the case of the TIG welding method, although the welding quality is excellent, the welding speed of the wire is extremely low, and the number of electrodes becomes too large when using multiple electrodes, making it impractical. Plasma welding is a highly efficient welding method, but the large welding torch makes the welding head too large to pass through the smallest size tubes.

The MIG welding method has a high welding speed, but the bead width is wide and at least two electrodes are required to fill a relatively deep groove. There is a problem that it is somewhat unstable and lacks welding reliability.

On the other hand, the hot wire TIG welding method was developed to improve the low wire welding speed, which is the weak point of the TIG welding method using a normal cold wire. The welding speed is about 3 times faster than the 20-30 gr/min of the cold wire method.

Therefore, the number of electrodes in the case of multiple electrodes can be reduced to about 1/3 using the hot wire TIG welding method, and at the same time, the TIG welding method has high shielding properties, smooth bead surfaces, and welding. The high quality of metal can be maintained.

The present invention utilizes the features of the hot wire TIG welding method as described above, and provides a welding device for clad steel pipes that can prevent arc interference due to magnetic blowing and achieve multi-electrode welding, as well as meet the above requirements. The purpose is to provide the following.

[Means for Solving the Problems] A clad steel pipe welding apparatus according to the present invention is capable of relatively moving a clad steel pipe, which is a member to be welded, and a welding boom, in which a plurality of TIG torches are arranged in series, so as to approach each other. The hot wire fed to the TIG torch is fed from the rear in the welding direction, and the TIG torch is fed from the rear in the welding direction.
Welding is carried out by setting the polarity of the G torch to negative, and passing positive direct current or alternating current through the hot wire.

[Function] In the clad steel pipe welding apparatus according to the present invention, the welding boom moves relatively to the clad steel pipe so as to approach each other. The inner and outer surfaces of can be welded in multiple layers in one run in the longitudinal direction. In this case, the hot wire was fed from the rear in the direction of welding progress, and the polarity was set to negative for the TIG torch and positive for the hot wire, so that direct current was applied or alternating current was applied to the hot wire. No arc interference due to blowing. Therefore, the interval between TIG)-chi can be reduced, and the number of electrodes can be increased.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, showing the case of four electrodes. In the figure, 1 is a member to be welded (hereinafter referred to as a pipe), which is placed on a trolley 2 and moves in the direction of arrow a. Therefore, the welding direction is the opposite b direction. 3 is a fixed welding boom, and a guide roller 4 that rolls on the inner surface of the vibrator 1 is provided at the tip. 5 is a TIG) which is arranged in series at a predetermined interval on the welding boom 3;
Each is connected to the minus side of the welding type R7 via a high frequency generator 6. The positive side of the welding power source 7 is connected to the vibrator 1. 8 is a hot wire guide nozzle arranged behind each welding torch 5 in the welding progress direction;
It has a power supply chip 9, and the power supply chip 9 is connected to the positive side of a hot wire power supply 10. 11 is a hot wire, which is connected to a pull feeder 12 and a bush feeder 1, respectively;
3, it is fed at a constant speed. Reference numeral 14 denotes a CCD camera installed at the tip of the welding boom 3 in order to perform groove tracing control.
7 can be monitored.

Reference numeral 18 denotes a CCD camera installed at the rear of the welding boom 3 to monitor the condition of the bead, and is designed to capture the reflected image from the mirror 19. Similarly, the CCD camera 18 captures the reflected image from the mirror 19. It is possible to monitor. 22 is a control panel, 23 is a drive device for the trolley 2, 2
4 is a shielding gas source, 25 is a pressure reducing valve, 26 is a flow rate adjustment device, 27 is a gas electromagnetic valve, and 28 is a cooling device for TIG)-chi 5.

Next, the operation of this embodiment will be explained.

The vibrator 1 is placed on a trolley 2, and is moved at a constant speed in the a direction by the operation of a drive device 23. A welding boom 3 facing the vibrator 1 enters into the vibrator 1. Before the welding boom 3 enters, an arc is generated on a tab plate (not shown) connected to the end of the vibrator 1 with the first TIG torch 5, and the hot wire 11 is fed at a constant speed. Perform hot wire TIG welding. When performing hot wire TIG welding, wire feed speed, heating power, arc length,
It is necessary to control welding parameters such as arc current with high precision, and in this embodiment, central control is performed using a control panel 22.

Now, as the welding boom 3 approaches, 2
3rd TIG torch 5.3rd TIG torch 5 generates an arc and performs hot wire TIG welding. Therefore, in this case, four layers of overlay welding are performed in one run.

FIGS. 2(a) to 2(d) show a lamination method when the number of electrodes is 2 to 4, and this example corresponds to FIG. 2(d). These lamination methods are selected depending on the size of the groove and the welding speed, but in either case, welding parameters for each electrode are set so that welding can be completed in one run.

Next, explaining the magnetic blowing of the arc, in the present invention, the hot wire 11 is fed to a plurality of TIG torches 5 from behind at a certain angle in the welding progress direction, and each TIG torch 5 Since the polarity of the TIG electrodes is negative and the polarity of the hot wire 11 is positive, direct current flows, the magnetic field between the TIG electrodes is mainly dominated by the one created by the hot wire current, and it is possible to prevent the arcs from attracting each other. can.

When a direct current of the above polarity is passed through the hot wire 11, an arc swings slightly forward, and when an alternating current is passed, an arc is generated almost directly below. Therefore, the interval between the TIG torches 5 can be reduced, and the number of electrodes can be increased. In addition, since the hot wire TIG welding equipment can be made smaller,
It can be sufficiently applied to even the smallest size of vibrator.

In addition, although the above-mentioned example explained overlay welding of the inner surface of a vibrator, overlay welding of the outer surface of a vibrator can also be performed in the same way.

[Effects of the Invention] As described above, according to the present invention, the multi-electrode hot wire T
By IG welding, the inner and outer surfaces of a clad steel pipe can be overlay-welded with high efficiency and precision, and manufacturing costs can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of an embodiment of the present invention, Figures 2 (a) to (d)
) is an explanatory diagram showing a lamination method when multiple electrodes are used. 1... Part to be welded 3... Welding boom 5... TIG torch 11... Hot wire representative Patent attorney Mune Sasaki Jiba 2 diagram

Claims (1)

[Claims] comprising a welding member and a welding boom that are movable in a direction in which they approach each other relatively, and a plurality of TIG torches that are arranged in series on the welding boom and can feed a hot wire from behind in the welding progress direction, A welding device for clad steel pipes, characterized in that the welding is performed by setting the polarity of the TIG torch to negative and passing a positive direct current or alternating current through the welding wire.