JPS6247629B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a narrow gap arc welding method and an apparatus therefor, which prevent the occurrence of welding defects such as poor fusion and automatically form a good welded joint.

In recent years, with dramatic advances in welding technology, narrow gap welding methods have been developed to reduce the width of the groove when welding large thick plate structures, etc., in order to shorten the work time. I've reached it. This narrow gap welding method is used exclusively for mark welding such as MIG welding, carbon dioxide gas welding, or submerged welding. abutting each other to form a narrow groove portion 2;
The guide tube 3 is moved along the narrow groove 2, and the consumable electrode 4 is fed into the guide tube 3, and an arc 5 is generated between the tip of the consumable electrode 4 and the workpiece 1. The pair of members to be welded 1 are welded together through the welded portion 6 thus formed. According to this narrow gap welding method, there is no need to form a special groove part by cutting on the workpiece 1, and since the narrow groove part 2 is used, the welded part 6
Because the amount of formation is small, it is possible to perform welding work with high efficiency.

However, in such narrow gap welding, since the groove width is narrow, the consumable electrode 4 is placed between the workpiece 1 and the welded part 6.
It is difficult to direct the weld to the corner of the weld, and in the past, unwelded portions 7 were often formed due to poor fusion between the welded member 1 and the layered welded portion 6. Therefore, there is a method of bending the consumable electrode 4 and welding the bottom surface of the narrow groove part 2 alternately on each side, a method of swinging and turning the consumable electrode 4 with a bending habit by a certain angle, or a method of giving the consumable electrode 4 a wave shape. A method of imparting a curved shape has been proposed, and has succeeded in forming a relatively good welded part with few fusion defects, and has achieved certain effects. However, all of these methods involve elastic bending of the consumable electrode 4, so that the tip of the consumable electrode 4 coming out of the guide tube 3 touches the workpiece 1.
The position of the guide tube 3 tends to fluctuate in the width direction of the groove, making it extremely difficult to adjust the welding conditions to a constant value. Furthermore, in addition to the feeding roller that feeds the consumable electrode 4, the devices that carry out these methods require a mechanism that bends the consumable electrode 4 and rotates it. This resulted in a large-scale device, which had drawbacks such as the device itself being expensive.

The present invention eliminates various drawbacks of such conventional narrow gap arc welding methods and devices, and
It is an object of the present invention to provide a method that can automatically form a good welded part without welding defects such as poor fusion, and a simple and inexpensive device that can carry out this method.

The configuration of the present invention relating to a narrow gap arc welding method that achieves this object is such that a pair of workpieces to be welded are opposed to each other to form a narrow gap, and a guide tube that moves along the narrow gap is placed in a guide cylinder. In a narrow gap arc welding method in which a consumable electrode is fed and an arc is generated between the tip of the consumable electrode and the member to be welded to weld the pair of members to be welded, the consumable electrode is connected to the guide tube. The narrow groove is plastically deformed in the width direction in a wave shape according to the welding conditions with an amplitude smaller than the inner width of the electrode, and the tip of the consumable electrode alternately touches the sides of the pair of workpieces without spring back. Further, the configuration of the present invention relating to a narrow gap arc welding apparatus is characterized in that a pair of members to be welded are opposed to each other to form a narrow gap, and a pair of feeding electrodes are arranged to sandwich and press a consumable electrode. By driving and rotating the feed roller, the consumable electrode is fed into the guide cylinder that moves along the narrow groove, and an arc is generated between the tip of the consumable electrode and the workpiece to be welded. In a narrow gap arc welding device for welding a pair of workpieces, the consumable electrode is bitten into the outer periphery of the pair of feed rollers by the drive circuit of the pair of feed rollers, and the consumable electrode is inserted into the guide cylinder. It is characterized by forming teeth that are plastically deformed in a wave-like manner with an amplitude smaller than the width.

In other words, the method of the present invention imparts complete plastic deformation to the consumable electrode and feeds the consumable electrode to the narrow gap without contacting the guide tube or the workpiece to be welded. This makes it possible to accurately position the guide cylinder relative to the welding part, and to form a good welded part without fusion defects. In addition, the device of the present invention devises the shape of the feed roller and plastically processes the consumable electrode into a wave shape using the feed roller, thereby making it possible to replace the conventional device by simply changing the feed roller. The invented method can be accomplished easily and inexpensively.

Hereinafter, an embodiment in which the narrow gap arc welding method and apparatus of the present invention are applied to MIG welding will be described in detail with reference to FIGS. 2 to 4.

As shown in FIG. 2 showing the external appearance of this embodiment, FIG. 3 a showing its schematic structure, and FIG. On the base 12 is a fixed bracket 14 that rotatably supports the first drive gear 13 connected to the feed roller drive motor 11.
and a movable bracket 16 that rotatably supports the second drive gear 15 that meshes with the first drive gear 13.
The first drive gear 13 and the second drive gear 15 feed the consumable electrode 19 that has passed through the straightening roller 17 and guide 18 installed above them into the guide cylinder 20. The feeding rollers 21 are each fixed coaxially. A tooth portion 22 is formed on the outer periphery of the pair of feeding rollers 21 to plastically deform the consumable electrode 19, which has been straightened by the straightening roller 17, into a zigzag wave shape. For fine adjustment, move the movable bracket 16 to the fixed bracket 1.
A pressurization amount adjusting screw 23 that can be moved toward and away from the base 12 and this movable bracket 16 to some extent
are screwed together. The feeding roller 21 in this embodiment includes a first drive gear 13 and a second drive gear 15.
The consumable electrode 19 can be plastic-processed into these shapes, as shown in FIGS. The feed roller with shaped teeth can be replaced as necessary depending on the welding conditions. The guide tube 20, which is inserted into a narrow groove 26 formed by opposing a pair of members 24 and 25 to be welded, is supported by a guide plate 27 fixed to the base 12, and 12, the connecting rod is attached to a sliding plate 28 that is movable in the width direction of the narrow groove portion 26 (in the horizontal direction in FIG. 2), and one end of the connecting rod is connected to the sliding plate 28. The other end of 29 is connected to a reduction gear 31 of an oscillating motor 30 installed on the base 12.
Therefore, by operating the oscillating motor 30, it is possible to oscillate the sliding plate 28 together with the guide tube 20 in the groove width direction. It should be noted that the consumable electrode 19 may be made of a strip-like material instead of a normal wire, and the reference numeral 32 in FIG.

The consumable electrode 19 that has come out of the guide 18 is caught in the teeth 22 of the feed roller 17, and the feed roller drive motor 12 is activated to feed the consumable electrode 19 into the guide tube 20, so that its tip is The operation of the feeding roller drive motor 11 is temporarily stopped when the guide tube 20 is penetrated, but the consumable electrode 19 is plastically worked into a zigzag wave shape as shown in FIG. It has become a state. Thereafter, the guide tube 20 is inserted into the narrow groove section 26, an arc 33 is generated between the consumable electrode 19 and the members to be welded 24, 25, and the guide tube 20 is inserted into the narrow groove section 26.
6 at a constant speed, and further operates the feeding roller drive motor 11 to move the consumable electrode 19 along the guide cylinder 2 at a speed equal to the consumption rate of the consumable electrode 19.
Feed within 0. In this case, it is necessary to supply inert gas or flux before and after the guide tube 20, but this is the same as in conventional MIG welding. As a result, the pair of members to be welded 24 and 25 are connected to the welded portion 3.
4, but since the tip of the consumable electrode 19 is wavy, as the consumable electrode 19 is consumed, it alternately points toward the welding parts 24 and 25, resulting in a good welding process with no welding defects such as poor fusion. A welded portion 34 is formed. Note that when the groove width is large, the oscillating motor 30 is operated to move the guide tube 20 to the consumable electrode 19.
It may also be made to reciprocate by a certain amount in the groove width direction at the same time. In addition to this oscillation, as shown in FIG. 5, which shows the general principle of another embodiment of the present invention, a pair of feed rollers 21 are connected to the consumable electrode 1.
By swinging the wavy consumable electrode 19 in the vertical direction in the figure, centering on the meshing part with the wafer electrode 9, the wavy consumable electrode 19 is further given a wavy bend, thereby directing its tip toward the workpieces 24 and 25. You may also try to increase your sex. However, in this case, it is necessary to widen the inner width of the guide cylinder 20 to prevent the consumable electrode 19 from coming into contact with the guide cylinder 20, which is exactly the same as in the above-mentioned embodiment. ,
Components that are the same as those shown in FIG. 3a are designated by the same reference numerals.

As described above, according to the narrow gap arc welding method and device of the present invention, teeth are formed on the outer periphery of the pair of feed rollers, and the teeth are used to plastically process the consumable electrode into a wave shape, so that the tip of the consumable electrode Since the feed rollers are arranged to alternately face the pair of workpieces without causing spring back, it is possible to form a good welded part without welding defects such as poor fusion. The mechanism is extremely simple, and the manufacturing cost is low.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the state of conventional narrow gap arc welding, Fig. 2 is a front view showing the external appearance of the narrow gap arc welding device according to the present invention, and Fig. 3a shows its working condition. Principle diagram, Figure 3b is part B
-B sectional view, FIG. 4 is a conceptual diagram showing each embodiment of the shape of the consumable electrode according to the present invention, and FIG. 5 is a third embodiment showing another embodiment of the narrow gap arc welding apparatus according to the present invention. It is a working principle diagram similar to figure a. In the drawing, 13 is a first drive gear, 15 is a second drive gear, 19 is a consumable electrode, 20 is a guide tube, 21 is a feed roller, 22 is a tooth portion, 24 and 25 are members to be welded, and 26 is a narrow opening. At the tip, 33 is an arc, and 34 is a welded part.

Claims (1)

[Claims] 1. A pair of workpieces to be welded are opposed to each other to form a narrow groove, a consumable electrode is fed into a guide cylinder that moves along the narrow groove, and the tip of the consumable electrode is In the narrow gap arc welding method of welding the pair of welded members by generating an arc between the welding member and the welded member, the consumable electrode is inserted into the narrow gap with an amplitude smaller than the inner width of the guide tube. A narrow gap characterized in that the consumable electrodes are plastically deformed in a wave-like manner in the width direction according to the welding conditions, and the tips of the consumable electrodes alternately face the pair of workpieces without spring back. Arc welding method. 2 A guide tube that forms a narrow groove by making a pair of welded members face each other, and moves the consumable electrode along the narrow groove by driving and rotating a pair of feed rollers that clamp the consumable electrode. In a narrow gap arc welding device that welds the pair of workpieces by feeding the consumable electrode into the welding body and generating an arc between the tip of the consumable electrode and the workpiece, the outer periphery of the pair of feed rollers A narrow gap characterized in that a tooth portion is formed that bites the consumable electrode and plastically deforms it in a wave shape with an amplitude smaller than the inner width of the guide tube as the pair of feeding rollers is driven to rotate. Arc welding equipment.