JPH0228426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has peripheral wall portions with an endless cross section like cylinders facing each other with a narrow annular groove, and moreover, a thick base material that extends over the entire circumference. This invention relates to an all-position narrow gap automatic welding method that performs single-sided uranami welding by repeatedly running from the outside.

When welding thick walls up to 100 mm using TIG welding, if the bevel angle of the welded part (base metal) is made large, the amount of wire consumed will increase.
Moreover, since the welding time becomes longer and the workability decreases, it is desirable to form a narrow groove with a small groove angle and perform narrow gap welding.

This type of welding method uses a non-consumable electrode and an inert gas while moving the welding mechanism along a narrow gap in the base metal (for example, the TIG welding method (for example,
55-24767, Japanese Patent Application Laid-Open No. 1983-137840) are known.

However, in the conventional method described above, multiple weld layers are laminated to form a thick weld, but the arc is cut each time one weld layer is formed, making the welding work intermittent. , it takes time to work. Moreover, once the arc is cut, a crater (concave portion) is likely to be formed at the welding end point, causing variations in the thickness of the entire weld layer. Therefore,
It may be possible to build up the weld layer so that the crater disappears when the arc restarts, that is, the weld layer at the end of the weld has a predetermined thickness, but in this case, the welding work will be troublesome. There is a problem that the work efficiency decreases.

Moreover, since this method simultaneously feeds both the wires on the front and rear sides of the electrode in the direction of movement, the wires on the back side of the electrode are welded without being sufficiently preheated, resulting in smooth melting of the wires. This results in a decrease in the thickness accuracy of the weld layer.

On the other hand, as another conventional example, in order to improve the thickness accuracy of the welding layer, there is a method of controlling pulse current conditions according to the posture of the welding head (for example,
100348) is known.

However, in this conventional example, the structure and control of the TIG welding device are complicated, and the work performance is also degraded. Moreover, since the wire is placed only on the front side in the direction of electrode movement, when the electrode is moved back to form a continuous weld layer, the wire will be located on the back side in the direction of movement of the electrode. preheating is insufficient, resulting in variations in the thickness of the weld layer.

This invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an all-position narrow gap automatic welding method that can continuously form a high-quality weld layer without variation in the thickness of the weld layer in a short time. With the goal.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

In Figures 1 and 2, reference numerals 1 and 1 indicate base metals (materials to be welded), which have an endless cross section like a thick-walled cylinder, and have an annular narrow opening with a groove angle of 5° or less. The circumferential portions 1a are opposed to each other at the tip 2, and both ends in the axial direction are fixedly supported by support means (not shown).

Reference numeral 3 denotes an endless rail, which is set on the outer periphery of one of the base materials 1, 1 at a predetermined interval h.

Reference numeral 4 denotes a welding mechanism, which is mounted on a cart 5 that can reciprocate in the directions of arrows A and B using the endless rail 3 as a guide.

The welding mechanism 4 includes a TIG welding torch body 6,
Side shield nozzles 7, 7 disposed close to both sides of the torch body 6, an annular gas cylinder 8 fitted externally so as to be slidable in the axial direction of the side shield nozzles 7, 7, and a TIG welding torch body 6. It is composed of wires 10a, 10b, etc., which are placed close to both sides of an electrode (non-consumable electrode) 9 protruding from the tip thereof.

The TIG welding torch main body 6 and the side shield nozzles 7, 7 are integrally connected by a tightening member 11 and fixed to a carriage 12, and are driven in the directions of arrows C and D ( The guide device 13 is connected to the carriage 5 so as to be able to reciprocate in the directions of arrows E and F (see FIG. 3).

14 indicates an operation panel. This operation panel 14 is a trolley 5
Equipped with welding power source, oscillation mechanism, AVC
It supports ON-OFF operation of mechanisms, trolley running mechanisms, etc., automatic sequence control, encapsulated gas control, welding condition control, etc.

15a and 15b are wire feeding mechanisms that sequentially feed and feed the wires 10a and 10b.

As is clear from FIG. 5, the side shield nozzles 7, 7 have an effective portion 7a formed with a thin wall _t2 , and an inert gas passage 7b and a cooling water circulation path 7c inside the body as shown in FIG. is formed. The gas passage 7b has a plurality of gas ejection holes 7d opened toward the TIG welding torch main body 6, a gas ejection hole 7e opened toward both sides, and a plurality of gas ejection holes 7e opened downward at the tip of the effective portion 7a. Each of them communicates with the gas ejection holes 7f.

As is clear from FIG. 7, the TIG welding torch main body 6 has a wall thickness t ₁ of the effective portion 6a equal to or less than the wall thickness t ₂ of the effective portion 7a of the side shield nozzles 7, 7. is formed.

Then, the outer periphery of the electrode 9 fixed to the tip of the effective portion 6a is bent to form a plurality of gas ejection holes 6b, as shown in FIG. It communicates with an inert gas passage 6c (see FIG. 6) formed inside the TIG welding torch main body 6.

Note that 6d indicates a cooling water circulation path.

Next, the method according to the present invention will be specifically described.

As shown in FIGS. 2 and 3, endless rails 3 are installed on the outer periphery of one of the base materials 1, which face each other with a narrow annular groove 2, at a predetermined interval h. It is assembled into a trolley 5 that can reciprocate on this endless rail 3. In this embodiment, two carts 5 are mounted on one endless rail 3.
(one not shown) is incorporated in each trolley 5,
A welding mechanism 4, a guide device 13, etc., which will be described later, are installed respectively.

With the trolley 5 stopped, the guide device 13 is moved forward and backward as appropriate in the direction of arrow E or F (FIG. 3), and the TIG welding torch main body 6, side shield nozzles 7, 7 and wire 10a of the welding mechanism 4,
10b is positioned above the annular narrow groove 2.

The carriage 12 is lowered in the direction of arrow C using the guide device 13 as a guide, and the effective portion 6a of the torch body 6, the effective portions 7a of the side shield nozzles 7, 7, and the fires 10a, 10b are removed as shown in FIGS. 2 and 3. Insert the tip of the electrode 9 into the narrow groove 2 as shown in FIG.
Correspond closely to the welding point.

In this embodiment, as shown in FIG. 9a, the welding mechanism 4 mounted on one trolley 5 (FIG. 1) is shown by a solid line, and the welding mechanism 4 mounted on the other trolley (not shown) is shown by a two-dot chain line.

First, the electrode 6 of the welding mechanism 4 shown by the above-mentioned solid line is brought close to the welding start point 2a of the narrow gap 2, and the electrode 6 of the welding mechanism 4 shown by the above-mentioned two-dot chain line is brought close to the welding start point 2a of the narrow gap 2.
Proximally correspond to the position overlapping b.

Next, turn on the welding power source switch on the control panel.
ON to generate an arc between the electrode 9 and the welding location of the base metals 1, 1, and the gas ejection hole 6b (8th ), and gas ejection holes 7d, 7e provided in the side shield nozzles 7, 7 in FIG.
Inert gas is ejected from 7f and also from the opening of the annular gas cylinder 8.

In this state, the torch body 6 shown by the solid line in FIG. 9a is moved from the welding start point 2a of the narrow gap 2 to the welding end point
While moving forward in the direction of arrow A until the electrode 9
Only one wire 10a located on the front side in the advancing direction is sequentially fed by one wire feeding mechanism 15a (FIG. 1) to the right side from the welding start point 2a to the welding end point 2b of the narrow gap 2. A first welding layer is formed over the entire half area.

At the same time, while moving the torch body 6 indicated by the two-dot chain line forward in the direction of arrow A from the position overlapping the welding end point 2b of the narrow gap 2 to the position overlapping the welding start point 2a, the welding mechanism 4 indicated by the solid line Similarly to the above case, a first welding layer is formed over the entire left half region from the remaining welding end point 2b to the welding start point 2a (first welding step).

Next, as shown in FIG. 9B, when the welding torch main body 6 shown by the solid line reaches the welding end point 2b of the narrow gap 2, the welding torch main body 6 shown in FIG. Raise the platform 12 appropriately, and
The guide device 13 is appropriately moved in the direction of the arrow E or F to perform welding with the electrode 9 of the torch body 6 corresponding to the welding location of the second layer and below. In other words, while moving the electrode 9 which has turned back the welding end point 2b without cutting the arc in the direction of arrow B toward the welding start point 2a, only the other wire 10b located on the front side in the direction of movement of the electrode 9 is moved. The wires are sequentially fed by the other wire feeding mechanism 15b (FIG. 1) to continuously form a second welding layer on top of the right half welding layer.

At the same time, when the welding torch main body 6 shown by the two-dot chain line reaches the position where it overlaps the welding start point 2a of the narrow gap 2, the electrode 9 remains energized, that is, the arc is not cut. As in the case of the welding mechanism 4 shown by the solid line above, a second welding layer is continuously formed over the left half welding layer (second welding step).

By repeating the series of operations of the first and second welding steps described above, it is possible to uniformly form a weld layer over the entire circumference of the narrow groove 2.

According to the above method, since the operation of the pair of wire feeding devices is switched and controlled so that only the wire 10a (or 10b) on the front side in the direction of movement of the electrode 9 is fed, the arc is not cut but is continuously fed. This makes it possible to perform welding with

Here, as described in the prior art, if the arc is once cut every time one welding layer is formed, a crater (concave portion) is likely to occur at the welding end point.
Therefore, it is necessary to build up the crater portion so that the crater is eliminated when the arc is restarted, that is, so that the weld layer at the welding end point has a predetermined thickness.

On the other hand, in the present invention, since welding is repeated without cutting the arc, even if a crater (concave portion) occurs at the welding end point 2b shown in FIG. When returning to the welding end point 2b and folding back, the crater portion is built up, so that variations in the thickness of the entire weld layer can be eliminated.

Moreover, since the welding lamination speed for each layer increases,
Highly efficient welding is possible in all positions.

Furthermore, since the wire on the rear side in the direction of movement of the electrode 9 is not fed, that is, only the wire on the front side in the direction of movement is fed, the wire is sufficiently preheated by the electrode, thereby melting the wire. This is done smoothly, and the thickness accuracy of the weld layer can be further improved.

As a result, a high-quality weld layer without weld defects can be formed in a short time.

Furthermore, in addition to the continuous welding described above, since the welding is repeated by starting from multiple points, the welding speed for each layer can be further improved, and highly efficient welding can be performed in all positions.

Furthermore, in this embodiment, the welding location that moves following the advancement of the trolley 5 is covered by an inert gas flow that is ejected from the gas ejection hole 6b of the TIG welding torch main body 6 shown in FIG. In addition, the gas ejection holes 7d, 7e, 7f of the side shield nozzles 7, 7
An inert gas curtain is formed around the outer periphery of the torch body 6 by the gas flow ejected from the opening of the annular gas cylinder 8. The inert gas flow ejected from the side shield nozzle 7,
Since an inert gas curtain is also formed around the outer periphery of 7, it is protected by a complete inert gas atmosphere. Therefore, proper welding of blowholes, narrow gaps, etc., which is essential for welding, becomes possible.

Furthermore, the TIG welding torch main body 6 has an effective portion 6
The wall thickness t ₂ of the effective portion _6a of the side shield nozzles 7, 7 is made thinner than the wall thickness t 1 (Fig. 7) of a.
(Fig. 5), the peripheral wall portion 1a (first part) is as thick as 100 mm.
Even if an annular narrow groove with an extremely small groove angle of 5° or less is formed in Figure), it can be easily inserted into the narrow groove and welding can be performed.

In the above embodiment, two carts 5 are provided on the endless rail 3 at equal intervals, but the present invention is not limited to this.
Alternatively, three or more carts 5 may be provided at regular intervals to shorten the welding work time.

[Effects of the Invention] As explained above, according to the present invention, it is possible to perform continuous welding in a narrow gap without cutting the arc, so it is possible to significantly shorten the working time and to achieve high quality welding without welding defects. A weld layer can be formed with high efficiency.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a welding device and base material used in the welding method according to the present invention, FIG. 2 is a front view of the same, FIG. 3 is a left side view of the same, FIG. 4 is a plan view of the same, and FIG. Figure 5 is an enlarged side view of the side shield nozzle, Figure 6 is an enlarged front view of the welding mechanism, and Figure 7 is an enlarged front view of the welding mechanism.
FIG. 8 is an enlarged side view of the TIG welding torch main body, FIG. 8 is an enlarged bottom view thereof, and FIG. 9 is a schematic sectional view for explaining the operating state of the welding mechanism. 1...Base metal, 1a...Periphery, 2...Narrow gap,
3... Endless rail, 4... Welding mechanism, 5...
... Cart, 6... TIG welding torch body, 9... Electrode, 10a, 10b... Wire, 12... Reciprocating table, 15a, 15b... Wire feeding mechanism.

Claims (1)

[Scope of Claims] 1. An endless rail 3 is set on the outer periphery of a base material 1 that faces each other with an annular narrow groove 2 and has a peripheral wall portion 1a with an endless cross section, and this rail 3 is used as a guide. A trolley 5 capable of repeated traveling is provided, and the trolley 5
, a welding mechanism 4 equipped with a side shield nozzle 7 for supplying inert gas, and a pair of wire feeding mechanisms 1.
5a, 15b, and the tip sides of the pair of wires 10a, 10b fed from the pair of wire feeding mechanisms 15a, 15b are connected to the welding mechanism 4.
The electrodes 9 are placed close to both sides of the electrodes 9 protruding from the tip of the TIG welding torch main body 6.
The tip sides of the pair of wires 10a and 10b are brought into close proximity to the welding location within the narrow gap 2, and the electrode 9 and the welding location within the narrow gap 2 are connected by energizing the welding power source. While generating an arc between the wires 10a, 10
An all-position narrow gap automatic welding method in which only the wire located on the front side in the direction of movement of the electrode 9 is sequentially fed in b to weld the entire circumference of the narrow gap 2, the electrode 9 being narrowly opened. While moving forward from the second welding start point 2a to the welding end point 2b, only one wire 10a located on the front side in the direction of movement of the electrode 9 is sequentially fed by one wire feeding mechanism 15a to narrow the wire. The first welding process forms a welding layer from the welding start point 2a of the groove 2 to the welding end point 2b, and the welding process of the electrode 9 when the electrode 9 reaches the welding end point 2b of the narrow groove 2. While the electrode 9 is running backward from the welding end point 2b to the welding start point 2a while maintaining the energized state, only the other wire 10b located on the front side in the direction of movement of the electrode 9 is transferred to the other wire feeding mechanism 15b. and a second welding process in which the next welding layer is continuously formed on top of the welding layer formed in the first welding process by sequentially feeding the welding layer by the welding process. Welding method.