JP5099083B2 - Control method and apparatus for multi-electrode welding apparatus - Google Patents

Description

  The present invention relates to a control method and apparatus for a multi-electrode welding apparatus that can use a plurality of torch electrodes simultaneously.

There is known a multi-electrode welding apparatus that allows a plurality of torch electrodes to be used at the same time in order to weld a plurality of rib materials to one plate material at the same time when groove welding is performed by matching the rib material to the plate material. Yes.
In such a multi-electrode welding apparatus, it is important to manage the arc voltage as in a normal single electrode welding apparatus. This is because the arc voltage is an important factor that affects the bead shape and the penetration depth. Therefore, it is necessary to keep the arc voltage constant. Conventionally, various methods for keeping the arc voltage constant have been proposed (see, for example, Patent Document 1).
As shown in Patent Document 1, a conventional arc voltage control method is generally based on feedback.

JP-A-52-85040

FIG. 4 is an explanatory view for explaining a multi-electrode welding apparatus, and shows a case where three ribs 21 are welded to a steel plate 5 (base material).
In the multi-electrode welding apparatus shown in FIG. 4, a pair of torch electrodes are arranged on both sides of the rib 21, and these are mounted on a gate-type device 25 that travels on the rail 23 so that they can move along the rib 21. Yes. In this example, three sets of torch electrodes [(F1A) (F1B)], [(F2A) (F2B)], [(F3A) (F3B)], and two sets of torch electrodes arranged rearward This is a case where there are a total of 10 electrodes [(B1A) (B1B)] and [(B2A) (B2B)], and the front 6 electrodes are operated.

  When welding is performed by a multi-electrode welding apparatus as shown in FIG. 4, the steel plate 5 is bent by heat, so that a force that curves in the opposite direction to the bending by heat is applied to the lower surface of the steel plate 5 in advance. A plurality of pressing grounds 27 are installed on the pressing plate that applies such force, and each pressing ground 27 is connected to the ground current collecting plate 7. The power supply device 29 is connected to the ground current collector plate 7 and is electrically connected to each torch electrode.

In the multi-electrode welding apparatus configured as described above, the rib 21 is welded by moving the portal apparatus 25 on the rail 23.
At the time of welding, in order to reduce the influence of heat, the pair of torch electrodes sandwiching the rib 21 are welded while being shifted forward and backward in the traveling direction.

In such a multi-electrode welding apparatus, welding is performed with a preset voltage, or welding is performed while correcting the voltage to a predetermined value by feedback control. When feedback control is performed, it is optimal that the arc voltage necessary for the control is detected between the torch electrode and the base material, but there is a possibility that the wiring contacts and is damaged by the movement or installation of the workpiece. As a solution to this, it is common to detect an arc voltage between non-movable parts, that is, between a ground current collector plate or a welding power source and a base material.
In such a multi-electrode welding apparatus, a situation where the bead shape and the penetration depth are not stable is seen, but the cause is unknown.

  The present invention has been made to solve such problems, and an object thereof is to obtain a multi-electrode welding method and apparatus capable of realizing stable welding.

  In order to solve the above-mentioned problems, the inventor conducted an experiment to find the cause of the arc voltage fluctuation in the multi-electrode welding apparatus. FIG. 2 is an explanatory diagram of the experimental apparatus, and the same components as those shown in FIG. 4 are denoted by the same reference numerals. In this experimental apparatus, for the torch electrodes [F2A, F2B, F3B], a voltage measuring device 31 is installed between the steel plate 5 (base material) and the ground current collector plate 7 in accordance with the progress of welding. The arc voltage was measured. FIG. 3 is a diagram showing this voltage waveform and voltage drop.

As can be seen from FIG. 3, there is a correspondence between the number of electrodes used and the resulting voltage drop. This is presumed that the ground current path is common to all torch electrodes, so that when there are a large number of torch electrodes in use, the resistance increases due to the influence of heat and the voltage drop increases. .
When the voltage drop according to the number of used electrodes was investigated based on FIG. 3, the result shown in Table 1 was obtained.

As can be seen from Table 1, a voltage drop of 0.1 V occurs as the number of torch electrodes to be operated increases by one. As described above, a voltage drop corresponding to the number of torch electrodes used is generated between the ground current collector plate 7 and the pressing ground (base material), but the voltage value set in the welding apparatus is a constant value. Therefore, the voltage drop generated between the earth current collector plate and the pressing earth (base material) corresponding to the number of torch electrodes used is ignored.
Even when feedback control is performed, the voltage used in feedback control is detected by the ground current collector plate. Therefore, the ground current collector plate and the pressing ground (mother) corresponding to the number of torch electrodes used are used. The voltage drop that occurs between the two materials will be ignored.
Based on this discovery, the inventor has found that if the voltage drop is assumed in advance and corrected in relation to the number of electrodes used, the influence of the fluctuation in arc voltage due to the number of electrodes used can be avoided with a simple configuration. Got.

  The present invention is based on such knowledge, and specifically has the following configuration.

(1) A control method for a multi-electrode welding apparatus according to the present invention has a plurality of torch electrodes, selectively operates the plurality of torch electrodes, and a ground electric path of the plurality of torch electrodes has a common path. A control method for a multi-electrode welding apparatus,
It is characterized in that welding is performed with a voltage that takes into account a predetermined correction voltage in accordance with the number of operating torch electrodes.

(2) A control device for a multi-electrode welding apparatus according to the present invention has a plurality of torch electrodes, selectively operates the plurality of torch electrodes, and a ground electric path of the plurality of torch electrodes has a common path. A control device for a multi-electrode welding apparatus,
Working electrode detection means for detecting a working torch electrode, and voltage correction for calculating a voltage correction amount based on an arithmetic expression set in advance in accordance with the input value detected by the detection value of the working electrode detection means And a control voltage setting means for setting a control voltage based on the voltage correction amount calculated by the voltage correction amount calculation means.

(3) Further, in the above (2), the arithmetic expression for calculating the voltage correction amount Vh is the following expression.
Vh = V1 × Tn
V1 is a preset voltage correction amount per electrode.
Tn is the number of active electrodes

  In the present invention, welding is performed with a voltage that takes into account a predetermined correction voltage in accordance with the number of torch electrodes that are in operation. Therefore, multi-electrode welding that can realize stable welding without complicated control. A method and apparatus can be realized.

It is explanatory drawing of the multi-electrode welding apparatus which concerns on one embodiment of this invention. It is explanatory drawing explaining the means for solving a subject, and is explanatory drawing of the apparatus used for experiment. It is explanatory drawing of an experimental result, and is a figure which shows a voltage waveform. It is explanatory drawing of a multi-electrode welding apparatus.

  FIG. 1 is an explanatory view of a multi-electrode welding apparatus according to an embodiment of the present invention. The multi-electrode welding apparatus according to the present embodiment has a pair of welding machines including an A robot welding machine 1A and a B robot welding machine 1B, and each welding machine has torch electrodes 3A and 3B, respectively. The electrodes 3A and 3B are selectively operated, and the first path 9 and the ground current collecting plate 7 between the base material 5 (steel plate) and the ground current collecting plate 7 with respect to the ground electrical paths of the plurality of torch electrodes. And the second path 11 between the welding machines 1A and 1B is a common path.

In addition, the multi-electrode welding apparatus according to the present embodiment has a working electrode detection unit 13 that detects a working torch electrode, and a detection value of the working electrode detection unit 13 that is input and preset according to the input value. A voltage correction amount calculation means 15 for calculating a voltage correction amount based on the calculated expression; a control voltage setting means 17 for setting the control voltage by inputting the voltage correction amount calculated by the voltage correction amount calculation means 15; It has. A ground-side voltage detector 19 is provided on the ground current collector plate 7 that collects ground electrical paths.
Each component will be described in more detail.

<Operating electrode detection means>
The working electrode detection means 13 detects the number of working electrodes, and detects the number of working electrodes by detecting a welding current value or a welding voltage value.

<Voltage correction amount calculation means>
The voltage correction amount calculation means 15 inputs the detection value of the working electrode detection means 13 and calculates the voltage correction amount Vh based on an arithmetic expression set in advance according to the input value. As an arithmetic expression set in advance, for example, the following expression (1) can be given.
Voltage correction amount: Vh = Va + Vp (1)
Here, Va corrects a voltage drop based on the fact that the first path 9 is a common path, and Va is determined by the following equation.
Va = V1 × Tn
V1: Voltage correction amount per electrode (for example, + 0.1V per number of working electrodes)
Tn: Number of working electrodes Vp corrects a voltage drop based on the fact that the second path 11 is a common path, and both the A robot welding machine 1A and the B robot welding machine 1B operate. The correction voltage amount is changed depending on whether one of them is operating. For example, when both the A robot welding machine 1A and the B robot welding machine 1B are in operation, the correction value is set to 0, and when either the A robot welding machine 1A or the B robot welding machine 1B is not operating. Is -1V.

<Control voltage setting means>
The control voltage setting unit 17 inputs the voltage correction amount calculated by the voltage correction amount calculation unit 15 and sets the control voltage. For example, when the set voltage value at the time of 6-electrode operation is 36V, if the voltage correction amount calculated by the voltage correction amount calculating means 15 is + 0.6V, the control voltage setting means 17 is 36.6V as the control voltage. Set.

<Voltage detector>
The voltage detector 19 detects the voltage at the earth current collector plate 7 and outputs it to the control voltage setting means 17. In the present embodiment, feedback control is not performed based on the voltage value detected by the voltage detector 19, but may be performed. Even in such a case, when the voltage detector 19 is provided on the ground current collector plate 7, the voltage drop in the first path 9 cannot be taken into consideration, and therefore, based on the voltage correction amount by the control voltage setting means 17. It is necessary to set the control voltage.

Next, the operation of the present embodiment configured as described above will be described. For example, the case where three ribs 21 are welded to the base material 5 (steel plate) shown in FIG. 2 and the welding proceeds from the state shown in FIG. 2 will be described as an example. In the state shown in FIG. 2, since all six electrodes are in operation and both of the pair of electrodes are in an operating state, the voltage correction amount Vh in this state is as follows.
Vh = 0.1V × 6 + 0 = 0.6V
Therefore, assuming that the basic set voltage is 36V, in this state, the voltage of each electrode set by the control voltage setting means 17 is 36.6V.

When the welding progresses, first, the welding by the electrode [F2A] and the electrode [F3A] is finished and the operation is stopped, and the working electrodes are the electrode [F2B], the electrode [F3B], the electrode [B2A], and the electrode [B2B] It becomes four. The number of working electrodes is detected by the working electrode detection means 13, and that effect is output to the voltage correction amount calculation means 15. In the voltage correction amount calculation means 15, since the number of operating electrodes is four, and the operation of one of the pair of electrodes is stopped for the electrodes [F2B] and [F3B], the voltage to each electrode is stopped. Correction amount: Vh is as follows.
Electrode [F2B] and electrode [F3B]: Vh = 0.1V × 4-1V = −0.6V
Electrode [B2A], Electrode [B2B]: Vh = 0.1V × 4 = 0.4V
Therefore, in this state, the voltage set by the control voltage setting means 17 is 36V-0.6V = 35.4V for the electrode [F2B] and the electrode [F3B], and 36V + 0.4V = for the electrode [B2A] and the electrode [B2B]. Set to 36.4V.

When welding further proceeds and the operation of the electrode [F2B] and the electrode [F3B] is stopped, the number of operating electrodes is two in this state, the electrode [B2A] and the electrode [B2B].
The voltage correction amount: Vh in this case is as follows.
Vh = 0.1V × 2 = 0.2V
Therefore, in this state, the set voltage for the electrode [B2A] and the electrode [B2B] is set to 36V + 0.2V = 36.2V by the control voltage setting means 17.

Further, when welding further proceeds and the operation of the electrode [B2A] is stopped, in this state, the number of active electrodes is only one of the electrodes [B2B]. Further, since the operation is performed only on one side of the pair of electrodes, the voltage correction amount Vh in this case is as follows.
Vh = 0.1V × 1-1V = -0.9V
Therefore, in this state, the control voltage setting means 17 sets the voltage to 36V-0.9V = 35.1V.

  As described above, according to the present embodiment, since the control voltage is set based on a predetermined arithmetic expression in accordance with the number of operating electrodes, the number of operating electrodes can be changed by simple control. Stable welding can be realized by preventing the adverse effect of the voltage fluctuation caused.

  In the above-described embodiment, an example in which the voltage correction amount corresponding to the working electrode is set to 0.1 V or −1 V has been shown, but the present invention is not limited to this, and these correction amounts are used. What is necessary is just to set it by investigating beforehand with a torch electrode, a base material, etc.

1A A robot welding machine 1B B robot welding machine 3A, 3B Torch electrode 5 Base material 7 Ground current collector plate 9 First path 11 Second path 13 Working electrode detection means 15 Voltage correction amount calculation means 17 Control voltage setting means 19 Voltage detection Section 21 Rib 23 Rail 25 Gate-type device 27 Pushing ground 29 Power supply device 31 Voltage measuring device

Claims (3)

A control method for a multi-electrode welding apparatus having a plurality of torch electrodes, selectively operating the plurality of torch electrodes, and having a common earth electrical path for the plurality of torch electrodes,
A control method for a multi-electrode welding apparatus, wherein welding is performed with a voltage that takes into account a predetermined correction voltage in accordance with the number of operating torch electrodes. A control device for a multi-electrode welding apparatus having a plurality of torch electrodes, selectively operating the plurality of torch electrodes, and having a common earth electrical path for the plurality of torch electrodes,
Working electrode detection means for detecting a working torch electrode, and voltage correction for calculating a voltage correction amount based on an arithmetic expression set in advance in accordance with the input value detected by the detection value of the working electrode detection means A control device for a multi-electrode welding apparatus, comprising: an amount calculation means; and a control voltage setting means for setting a control voltage based on the voltage correction amount calculated by the voltage correction amount calculation means. 3. The control apparatus for a multi-electrode welding apparatus according to claim 2, wherein an arithmetic expression for calculating the voltage correction amount Vh is the following expression.
Vh = V1 × Tn
V1 is a preset voltage correction amount per electrode.
Tn is the number of active electrodes

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