JP2701666B2 - Arc Start Bead Meeting Method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of associating arc start beads for connecting the start ends of first and second weld beads by rotary arc welding.

[0002]

2. Description of the Related Art In known rotary arc welding, the rotational positions (Cf, R, Cr) of an arc rotating at a high speed with a predetermined radius are known.
, L), the arc voltage and the welding current waveform at predetermined angles are detected at the left and right, respectively, around the forward point Cf in the welding advancing direction, and control is performed so that the integrated values of the left and right become equal. A groove copying control of a copying arc sensor method is performed (Japanese Patent Laid-Open No. 62-248571).

[0003] Such a rotary arc welding method is widely used for butt welding, fillet welding, and the like. For example, the same applies to circumferential welding of a narrow groove of a pipe. However, in the case of pipes, in order to achieve high-efficiency welding, generally two welding machines, ie, a leading welding machine (hereinafter, referred to as a first welding machine) and a succeeding welding machine (hereinafter, referred to as a second welding machine) are used. The left and right halves are to be welded.

[0006] That is, as schematically shown in FIG. 6, the first welding machine 1 is started from the “top” (point A) of the pipe 10,
Welding is performed in the direction of arrow a to “ground” (point B), and the left half circumference is welded. Similarly, the right half of the circumference is welded by the second welding machine 2, but the first welding machine 1 and the second welding machine 2 cannot be started simultaneously from the same point A. Start arc from point A,
After returning the second welding machine 2 to the point A in the direction c with a delay,
The welding is started by a method such as an arc start in the direction b. In this way, the left and right weld beads (not shown) are connected by “heaven” and “ground”, respectively. In the figure,
Reference numerals 3 and 4 respectively denote a first electrode nozzle and a second electrode nozzle for rotary arc welding. Reference numerals 5 and 6 denote a first welding wire and a second welding wire, respectively. The circumferential guide rails 9 are wheels of each of the welding machines 1 and 2 running on the guide rail 8.

By the way, conventionally, when connecting the right and left welding beads with “top”, the wire rotation position of the rotating arc is set at the Cf point in front of the welding traveling direction in order to activate the arc sensor from the start. Was. 7 to 9
Figure 1 shows an outline of the conventional arc start bead association method.

FIG. 7 is a schematic plan view of a bead meeting portion, and FIG. 8 is a sectional side view thereof. FIG. 9 is a sectional front view of the bead meeting portion. In the first welding machine 1, the first welding wire 5 is set at a point Cf shifted leftward by the rotating diameter D of the rotating arc from the point A, and when it is confirmed that an arc has been generated at the point Cf, the first welding wire is set. The machine 1 is started to form the first weld bead 11 on the left. After that, the second welding wire 6 of the second welding machine 2 is set to the Cf point shifted rightward by the rotating diameter D of the rotating arc from the point A, and an arc is generated. Start,
The right second weld bead 12 is formed. Therefore, the start end 11a of the first weld bead 11 and the second weld bead 12
Of the welding beads 11 and 12 can be connected to each other at point A.

[0007]

However, if the set positions of the first and second welding wires 5 and 6 at the time of the arc start are both set at the Cf point, the welding machine starts immediately after the arc is generated and confirmed. Since the fusion portion between the start end 11a of the first weld bead 11 and the start end 12a of the second weld bead 12 is shortened, and since the bead start end 11a of the first welder is cooled at the time of arc start of the second welder, As shown in FIG. 8, there is a problem that the penetration does not become uniform at the junction 13 between the left and right weld beads 11, 12. In particular, the back bead may not be connected in the first layer reverse wave welding, and a welding defect such as poor fusion may occur in the joint portion 13.

Further, if the shift amount of the welding wire is corrected in advance in consideration of the deviation of the bead starting end, the above-mentioned problem can be solved, but the calculation of the shift amount requires too many factors and is extremely troublesome.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make the penetration at the junction of the arc start bead uniform by a simple method and improve the quality thereof. It is to plan.

[0010]

According to the present invention, in a first welding step, an arc start position of a rotating arc is set to a rear point Cr in a welding advancing direction, thereby forming a first welding bead and then a second welding bead. In the process, the arc start position of the rotating arc is also set to the rear point Cr in the welding traveling direction, and the position is aligned with the starting end of the first welding bead and welding is performed in the opposite direction to the above. This problem has been solved by using a method of associating an arc start bead for connecting two weld beads with the first weld bead.

Further, according to the present invention, the arc start position of the rotating arc in the first welding step is set to the forward point Cf in the welding traveling direction as in the conventional case, and only the arc starting position of the rotating arc in the second welding step is set as described above. Similarly, it is set as the rear point Cr in the welding progress direction and at the position of the start end of the first welding bead.

[0012]

In the first welding machine used in the first welding step,
When the arc rotation is started with the wire rotation position set to the above-mentioned Cr point, the arc starts at the Cr point, so that the back lining of the first layer can be more preferably made than at the point A.

In the second welding step, the wire rotation position of the second welding machine is set to the same Cr point, and the starting position of the already formed first welding bead is automatically positioned using experimental values. By performing the arc start together, the second weld bead can be uniformly fused with the start end of the first weld bead. The back bead of the first layer can also be connected well at this bead meeting portion.

Next, when the wire rotation position of the first welding machine is set to the Cf point as in the conventional case, the starting end of the first welding bead is similarly set, and the wire rotation position of the second welding machine is the C r point. Since the position is automatically determined using the experimental value, the position can be aligned with the start end of the first weld bead, and the two beads can be satisfactorily associated with each other as described above.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below by taking the case of circumferential welding of pipes as an example. FIG. 1 is an explanatory view showing an outline of a method of associating arc start beads according to one embodiment of the present invention, and is a schematic plan view of a bead associating portion. FIG. 2 is a sectional side view of the bead meeting portion, and FIG. 3 is a sectional front view of the bead meeting portion. The arrangement of the first welding machine 1 and the second welding machine 2 is the same as the conventional one (see FIG. 6).

In this embodiment, first, a first welding step is performed using a first welding machine. At this time, the wire rotation position of the rotary arc of the first welding machine is set to the rear point Cr in the welding advancing direction a, and the position is adjusted to the “top” of the pipe 10, that is, the point A. Then, the arc is started at this position to form the first weld bead 11. In addition, the groove tracking control of the arc sensor system is controlled by using an arc voltage and a welding current waveform of a predetermined angle on the left and right sides around the Cf point as in the conventional case.

As described above, since the arc is started at the point Cr, even if the first welding machine is started immediately after the occurrence of the arc is confirmed, the first layer back bead 11b can be formed better than the point A. That is, in the experimental example, the arc is generated and the arc rotates and the truck runs for 100 to 400 ms. During this time, the arc stops at the Cr point, so that the first layer back bead immediately below the Cr point is easily formed.

After forming the first welding bead 11 in this manner, in the second welding step, the wire rotation position of the rotating arc of the second welding machine is set to the rear point Cr in the welding traveling direction b, and While being stopped at the Cr point, it is moved to the point A side, and is automatically adjusted to a position to be the starting end 11a of the already formed first welding bead 11 using experimental values. Then, the arc is started at this position, and welding is performed in the direction b to form the second weld bead 12 and fuse with the start end 11a of the first weld bead 11 to connect the beads 11, 12.

By setting the set position of the second welding wire 6 at the Cr point and at the position of the starting end 11a of the first welding bead 11, even if the starting end 11a is cooled, the heat generated by the arc heat generated at that position is obtained. The starting end portion 11a is easily melted and can be well fused with the second weld bead 12. Therefore, the fusion at the bead meeting portion 13 is performed uniformly, the first layer back bead 12b can be connected well to the first first layer back bead 11b, and no welding defect such as poor fusion occurs at the bead meeting portion 13. .
The groove following control of the second welding machine is also performed using the arc voltage and welding current waveforms at predetermined angles on the left and right sides centering on the point Cf in the same manner as described above.

The positioning of the wire rotation position of the second welding machine is performed by adjusting the distance G (experimental value) between the rotation center axis 15 of the first welding wire 5 and the rotation center axis 16 of the second welding wire 6.
Is simply set at a position that is substantially separated by the rotation diameter D of the rotating arc.

Next, FIG. 4 is a schematic plan view of a bead meeting portion showing another embodiment of the present invention, and FIG. 5 is a sectional side view thereof. In this embodiment, the wire rotation position of the first welding machine is set to the forward point Cf in the welding advancing direction a as in the conventional case, and only the wire rotation position of the second welding machine is set to the welding advancing direction b in the same manner as described above.
At the rear end Cr of the first welding bead 11 and the position of the starting end 11a of the first welding bead 11.

When the arc rotation is started with the wire rotation position of the first welding machine set at the point Cf, the starting end 11a of the first welding bead 11 is obtained. Since the wire rotation position of the second welding machine is set to the Cr point as described above, an experimental value is used at a position where the second welding wire 6 is stopped at the Cr point and the starting end 11a of the first welding bead 11 is used. Align,
If the arc is started, both beads 1
1, 12 can be satisfactorily associated, and the fusion of the bead association portion 13 can be uniform.

Contrary to the above-described embodiment, when the wire rotation position of the first welding machine is set to the point Cr and the wire rotation position of the second welding machine is set to the point Cf, the starting end 1 of the first welding bead 11 is set.
In the position 1a, the arc does not reach until the arc is generated and rotated, and the vehicle travels immediately, so that a sufficient amount of heat for forming the back bead cannot be obtained. Therefore, it is difficult to obtain a uniform weld bead.

It should be noted that the present invention is not limited to the case of circumferential welding of pipes using two first and second welding machines as in the above embodiment, and one welding machine may be used. ,
In addition, the present invention can be applied to any welded joint as long as the arc start bead is associated.

[0025]

As described above, according to the present invention, in both the first welding step and the second welding step, the arc start point of the rotating arc is set to the rear point Cr in the welding advancing direction. Since the Cr point is aligned with the starting end of the existing first weld bead and welded,
The fusion of the bead joints can be made uniform, the quality can be improved, and the back bead can be satisfactorily associated even in the first layer reverse welding.

The same effect as described above can be obtained even when the arc start point in the first welding step is set to the front point Cf in the welding direction and the arc start point in the second welding step is set to the rear point Cr in the welding direction. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a bead meeting portion according to an embodiment of the present invention.

FIG. 2 is a cross-sectional side view of the bead meeting portion.

FIG. 3 is a sectional front view of the bead meeting portion.

FIG. 4 is a schematic plan view of a bead meeting portion according to another embodiment of the present invention.

FIG. 5 is a cross-sectional side view of a bead meeting portion in the embodiment of FIG. 4;

FIG. 6 is an explanatory view of a conventional pipe circumferential welding method.

FIG. 7 is a schematic plan view of a conventional bead meeting portion.

FIG. 8 is a cross-sectional side view of the bead meeting portion in FIG. 7;

FIG. 9 is a cross-sectional front view of the bead meeting portion in FIG. 7;

[Description of Signs] 1 First welding machine 2 Second welding machine 3 First electrode nozzle 4 Second electrode nozzle 5 First welding wire 6 Second welding wire 7 Groove 10 Pipe 11 First welding bead 11a First welding bead Start end of second weld bead 12a Start end of second weld bead 13 Bead joint

Claims (2)

(57) [Claims] 1. An arc start bead associating method for connecting start ends of first and second weld beads by rotary arc welding, wherein an arc start position of the rotary arc is set to a rear point Cr in a welding traveling direction. A first welding step of forming a first welding bead, and setting an arc start position of the rotating arc at a rear point Cr in the same welding progress direction, and aligning the position with a starting end of the first welding bead. A second welding step of welding in a direction opposite to the above and connecting a second weld bead to the first weld bead. 2. An arc start bead associating method for connecting start ends of first and second weld beads by rotary arc welding, wherein an arc start position of the rotary arc is set to a forward point Cf in a welding advancing direction. A first welding step of forming a first weld bead, and setting an arc start position of the rotating arc at a rear point Cr in a welding traveling direction, and aligning the position with a start end of the first weld bead. And a second welding step of welding the second weld bead to the first weld bead in a direction opposite to the first direction.