JP3308826B2 - Welding torch set 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 welding torch setting method, and more particularly, to a welding start position which is correct when an object workpiece is subjected to arc welding using an automatic welding machine or a welding robot due to an assembly error, a setting error and the like. The present invention relates to a suitable welding torch setting method in a case where a workpiece cannot be set at a predetermined position, or when it is difficult to correctly guide an electrode to a welding starting position when a groove bottom is difficult to see as in narrow gap (narrow gap) welding.

[0002]

2. Description of the Related Art Guidance to a welding starting position is almost always made visually by an operator.

As a conventional example, as shown in FIG. 7, the electrodes of a welding torch are moved in parallel in a groove to the left and right, and the contact positions on the left and right of the groove are respectively detected by potentiometers, and the average of each position at that time is detected. Calculate the value and set the groove center position X
There is a method for obtaining c.

However, in this method, the welding torch is not guided to the welding start position, and the nozzle of the torch hits a groove wall in a narrow groove of a thick plate, so that it is used only for detecting the position of the groove on the very surface. Can not. Therefore, the method cannot be applied to narrow groove welding of a thick plate, so that the burden on a welding operator is not reduced, and a correct welding torch cannot be set.

[0005]

In starting arc welding, the tip of the electrode must be set at a position substantially at the center of the welding groove and at a predetermined distance (about 1 to 3 mm) from the bottom of the groove. No. Otherwise, the arc activation will fail, or the arc will be extinguished immediately after activation. In particular, the starting position of the groove of a thick plate joint or the narrow groove joint is difficult to see because the welding torch or the groove wall is an obstacle, so the welding worker takes time, time and nerves considerably. You have to focus.

When a gap between the torch and the groove side wall is smaller than the distance between the electrode tip and the groove bottom in the narrow groove welding of a thick plate, when a high frequency voltage for arc start is applied, the high frequency and the arc are short. Since the arc is generated from the side, the arc is generated not from the tip of the electrode but from the side of the torch and damages the torch.

Therefore, according to the present invention, the starting position of arc welding can be set automatically and accurately.
These problems are solved.

[0008]

According to the apparatus of the present invention, as shown in FIG. 1, an inclined electrode 4 having a tip of a oscillating electrode bar 3 and a tungsten electrode attached to the tip of the electrode bar 3 at an angle of 5 to 40 degrees to protect the arc. It is installed in the shield gas nozzle 5. An arc welding power source 10 is connected to the electrode rod 3 and the base material 2 to supply a welding current.

In order to fill the base material 2 with molten metal,
The filler wire 9 is pulled out from the wire reel 8 by the feed roller 6 driven by the feed motor 7 and is supplied to the melting portion. In this embodiment, the wire current is supplied from the power supply 11 to the filler wire to further increase the melting efficiency. Further, if the amount of melting is increased by increasing the wire current, the arc is affected by the magnetic blowing. In this example, the arc current and the wire current are switched by the switching control 12 and are alternately energized.

[0010] oscillation motor M _theta 13 for swinging the electrode shown in FIG. 2 for carrying out the present invention, the slide shaft Y and a driving motor M _Y 14 to correct the swing position, the swing electrode vertically Slide axis Z to slide and its drive motor M
_Z 15 and a contact detection device 16 for detecting contact between the inclined electrode 4 and the base material 2. The electrode detection device of this example supplies a DC or AC voltage of about 5 to 30 V through a high resistance such as 1 kΩ, and detects a contact state between the electrode and the base material by a voltage change of an output terminal or a current change. I have.

In the present invention, power supply to the filler wire shown in FIG. 1 is not always necessary, and the filler wire may not be provided. According to the second aspect, a method of detecting the contact with the groove wall by pendulum operation (weaving) of the electrode 17 by the drive mechanism 18 as shown in FIG.

When the inclined electrode 4 is oscillated at the upper portion of the groove shown in FIG. 2 using the means described above, if the center of the oscillating axis is displaced from the center of the groove, one side (R side) comes into contact. However, there is no contact on the opposite side (F side). As the Y-axis is slightly moved to the F side in the slide motor M _Y when. The swinging operation and the sliding operation are repeated until the tip of the electrode comes into contact with both walls of the groove. In the swinging operation, the amplitude is first started from a small value and gradually widened, and the unit slide amount on the Y axis is also given an appropriate value (0.02 to 0.10 mm).

When both walls of the groove are detected, since the electrode rod 3 is almost at the center of the groove, the swinging operation stops the inclined electrode 4 toward the center of the groove (= weld line direction). Thereafter, the inclined electrode 4 is moved by the vertical slide shaft 15 toward the groove bottom (root portion). The contact between the inclined electrode 4 and the base material 2 is detected by a contact detection power supply 16, and thereafter the inclined electrode 4 is moved to an appropriate distance (1 to 3).
mm) Pull up to complete the torch set. Thereafter, a high frequency (HF) voltage is applied between the electrode and the base material to cause discharge, and an arc current is supplied from the welding power source 10 to shift to a welding arc. A third aspect is a method in which the welding is switched to a welding arc by performing a pull-up operation while supplying a current from the welding power source 10 immediately after the contact of the electrode 4 with the base material 2 is detected.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the system of the present invention is shown in FIG.
An oscillating TIG welding device as shown in FIG. 2 was used. This device includes a welding torch (oscillating electrode rod 3, inclined electrode 4, torch nozzle 5), a wire feeder (feed roller 6, feed motor 7, wire reel 8, filler wire 9), and a welding machine (arc welding power source 10). , Wire power supply 11, switching control 1
2), a moving mechanism (electrode swinging mechanism 13, Y-axis slide mechanism 14, Z-axis slide mechanism 15), and a contact detection device 16. A torch set control device (not shown) is incorporated in a general control device (not shown) for controlling them collectively, and a welding torch set is realized by controlling each device as described below.

In the software program for controlling the welding operation, the on / off of the torch set switch is monitored as shown in FIG.
Set T to 1 and enter the torch set subroutine. This subroutine has the configuration shown in FIG.
Since TSET starts with 1, go to “Torch set / center copying start” first. Here, various initial values required for control are set. For example, the initial value of the swing amplitude (swing angle), the increase width of the amplitude (angle), the maximum / minimum amplitude values, the detection sensitivity, etc. are set, the flag F_TSET is set to 2, and the process returns to the main routine. Next, go around in the main routine,
The routine for examining F_TSET (FIG. 4) is entered, and F_T
Since SET is not 0, the subroutine of the torch set is again entered (FIG. 5). Since the flag is set to 2, the subroutine of "torch set / center copying" is entered. In this way, the torch set program proceeds.
The details of the subroutine of “torch set / center copying” will be described later, but as a result of the processing, the electrode is guided to the center of the groove. When the torch is guided around the groove, the flag F_TS
Set ET to 3 and return to the main routine. Subsequently, since the flag is 3 in the torch set subroutine, the subroutine "torch set / origin return" is entered. Here, control is performed to direct the inclined electrode toward the center of the welding line direction (the center position of the swing). When completed, advance the flag to the next, "Bottom detection"
Subroutine. Here, the Z axis of the slide base is moved toward the groove bottom, the operation is stopped by the contact signal of the contact detection device, and the next flag is set to exit. Next, the subroutine "Waiting for reversal" is entered, in which the moving direction of the torch is reversed to control the torch to move away from the groove bottom.
Subsequently, a subroutine "gap formation" is entered, and the gap amount (1 to 3 mm) is set to an appropriate value. When the gap amount is formed, the flag F_TSET is set to 0, and the torch set process ends.

The guiding of the welding torch to the groove center is shown in FIG.
The subroutine "Torch set / center copying" shown in FIG. Here, we start with a small amplitude swing.
The presence or absence of contact on the F side is detected.
One. Next, it is inverted to the R side, and the presence or absence of contact with the R wall is detected. Similarly, when there is no contact, the amplitude is increased by one. This process is performed alternately each time the electrode swings to the R side and the L side. When the contact occurs, the amplitude is reduced, but a slightly larger value (a value of 2 in this example) is given so as not to damage the electrode. In addition, maximum and minimum values are given to the swing amplitude so as not to swing any more.

Next, the difference between the left and right amplitudes is calculated to determine the Y of the torch.
Determines the axial sliding movement. In this example, R side amplitude−F side amplitude = C is calculated, and if C−3> 0, the torch is moved to the F side,
If <0, move the torch to the R side. If C is in the meantime, the sliding operation of the torch is stopped, and the contact flags in the F and R directions are checked. If both contact flags are raised, that is, the electrodes have come into contact with both the groove walls. Therefore, the torch set flag is set to the following 3, and this subroutine is terminated. Therefore, the welding torch moves to the middle position of the groove, and this process ends.

A third aspect is a method for starting arc welding immediately in the process of setting a welding torch. In the embodiment of the present invention, simultaneously with or immediately before the operation of raising the predetermined distance in the "gap formation" subroutine of FIG.

This embodiment makes it possible to easily detect a welding start position and start welding from a correct position, and can be widely used for automatic welding of structures in general. It also helps to simplify the teaching work of the welding robot. In the present invention, TIG arc welding is mainly used, but the present invention can also be applied to MAG / MIG arc welding.

[0020]

According to the present invention, the setting of the position of the torch in the groove in the welding preparation operation is automated, and the burden on the operator can be greatly reduced. Especially thick boards,
In a large structure, it is very difficult for the worker to approach the welding start position, and the work of setting the center position and distance of the deep groove bottom which is difficult to see from the groove surface can be automatically set remotely according to the present invention. . As a result, the reliability and work efficiency of the welding start are increased, and the failure of the start portion where defects are likely to occur is reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of a device configuration employed in the present invention.

FIG. 2 is a diagram illustrating the principle of the welding torch set of the present invention.

FIG. 3 is an explanatory view of an electrode pendulum operation mechanism of the present invention.

FIG. 4 is a diagram showing a flowchart of a software program of a main routine of the present invention.

FIG. 5 is a view showing a flowchart of a “torch set” subroutine program of the present invention.

FIG. 6 is a diagram showing a flowchart of a “torch set / center copying” subroutine program of the present invention.

FIG. 7 is a diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tungsten electrode, 2 ... Base material, 3 ... Swinging electrode rod, 4
... tilt electrode, 5 ... torch nozzle, 6 ... feed roller, 7 ...
Feed motor, 8: wire reel, 9: filler wire, 1
0 ... arc welding power supply, 11 ... wire power supply, 12 ... switching control, 13 ... electrode swing mechanism, 14 ... Y axis slide mechanism, 15 ... Z axis slide mechanism, 16 ... contact detection device,
17: pendulum (weaving) electrode; 18: pendulum operation drive mechanism.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Hara 3-1-1, Sachimachi, Hitachi-City, Ibaraki Pref. Hitachi, Ltd. Inside the Hitachi Plant (72) Inventor Kazutaka Hosokawa 3-1-1, Sachimachi, Hitachi, Ibaraki No. 1 Hitachi, Ltd. Hitachi Plant (72) Inventor Kazushi Suzuki 3-1-1 Komachi, Hitachi City, Ibaraki Prefecture Hitachi, Ltd. Hitachi Plant (72) Inventor Noboru Saito 502 502 Kandatecho, Tsuchiura City, Ibaraki Prefecture Hitachi, Ltd.Mechanical Research Laboratory Co., Ltd. Inside the Kure Research Institute (72) Inventor Nobuo Nakazawa 3-36 Takaracho, Kure City, Hiroshima Prefecture Babcock Hitachi Ltd. Inside the Kure Research Institute (72) Person Toshiaki Takuwa 6-9 Takara-cho, Kure City, Hiroshima Prefecture Inside the Kure Factory, Babcock Hitachi Ltd. (72) Inventor Toshiharu Nagashima 6-9 Takaramachi, Kure City, Hiroshima Prefecture Inside the Kure Factory, Babcock Hitachi Ltd. (56) References JP-A-4-228266 (JP, A) JP-A-62-2895 (JP, A) JP-A-59-50970 (JP, A) JP-A-8-39247 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 9/127 B23K 9/067 B23K 9/29 B23K 35/02

Claims (4)

(57) [Claims] 1. A power source for detecting contact with a base material is connected to a welding torch that swings by rotating an inclined electrode left and right within a groove,
Judging the contact with the base material from the change in current or voltage of the power supply, the electrode is swung so as to increase from small amplitude in the groove, and the presence or absence of contact with the left and right groove walls is alternately determined. If the electrode does not contact the groove wall,
When the amplitude is increased and contact with one of the groove walls is detected
In addition, while reducing the swinging amplitude of the electrode, the slide base holding the welding torch is brought into contact with the slide base.
Move to the opposite side of the detected groove wall to swing the electrode
The operation and slide base operation are repeated, and the electrode is opened.
When the contact with both walls is detected, the movement of the slide base is stopped, the direction of the inclined electrode is returned to the center, the swing is stopped, and then the electrode is slid vertically toward the groove bottom. The base is moved and stopped immediately when the contact with the groove bottom is detected by the contact detector, and then the welding torch is continuously pulled up for a certain distance or for a certain period of time to set the starting position of the welding arc. Welding torch set method. 2. The welding torch setting method according to claim 1, wherein the contact with the groove is detected by a pendulum operation of the electrode instead of the rotational swing operation of the electrode. 3. The welding torch setting method according to claim 1, wherein a welding voltage / current is supplied immediately after the contact of the electrode with the groove bottom is detected, and the welding torch is simultaneously pulled up. 4. A power source for detecting contact with a base material is connected to a welding torch that swings by rotating an inclined electrode left and right within a groove,
Judging the contact with the base material from the change in current or voltage of the power supply, the electrode is swung so as to increase from small amplitude in the groove, and the presence or absence of contact with the left and right groove walls is alternately determined. If the electrode does not contact the groove wall,
When the amplitude is increased and contact with one of the groove walls is detected
In addition to reducing the amplitude of the oscillation of the electrode,
The contact slide base that secures the welding torch
Move the electrode to the opposite side of the detected groove wall so that the electrode
The electrode swings and slides until it contacts both walls.
A welding torch setting method, wherein the center of the swing shaft is moved to the center of the groove by repeating the operation of the welding torch.