JP3399490B2 - Arc welding method and arc welding robot - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc welding method and an arc welding robot.

[0002]

2. Description of the Related Art Conventionally, in arc welding, arc voltage-current characteristics of an arc welding machine and wire feeding speed-
The current characteristics are measured in advance, the power supply command value and the wire feed speed command value of the welding machine that obtain the desired welding current and welding voltage are determined, and the welder is determined by the power supply command value and the wire feed speed command value. Driven to obtain desired welding current and welding voltage,
Welding is performed by adjusting the power supply command value and wire feed speed command value because the welding current and welding voltage vary slightly depending on the shape of the groove, the target position of the wire, and the wire protrusion length.

[0003]

However, in the above-mentioned method, welding must be carried out under conditions every time the power supply command value and the wire feed speed command value are changed, which is a waste of labor. In addition, welding has been performed with a difference between the desired welding current and welding voltage command values and the actual welding current and welding voltage. In particular, the fluctuations in the welding current and welding voltage due to the fluctuations in the primary side voltage on the welding power source side are large, and they fluctuate more than the welding current and welding voltage when the conditions were set in advance, causing arc instability and arc breakage. Occurs,
The robot may stop during welding, or “insufficient melting”, “breakage”, and “bead break” may occur at the welding location, resulting in a decrease in welding operation rate and a decrease in welding quality.
As a method for solving such a problem, Japanese Patent Application Laid-Open No. Hei 3
There is a method described in JP-A-86376. this is,
The welding current / welding voltage on the secondary side of the welding machine is detected every predetermined period, and the average value of the welding current and the welding voltage is obtained each time the detected value reaches a predetermined number, and the average value and the welding current command value and Calculate the error from the welding voltage command value and feed the wire to the welding machine based on the error in the welding current until the errors fall within the setting tolerance range and the welding current error falls within the setting range. This is a control method for correcting the speed command value and correcting the power supply command value to the welding machine based on the error of the welding current and the error of the welding voltage. However, this method cannot identify whether the welding current value / welding voltage value changes due to the change in the primary side voltage of the welding machine, or the gap resulting from the shape of the work piece / the welding current / welding voltage due to temporary attachment. . That is, if the variation is caused by the gap or temporary attachment caused by the shape of the work, if the variation of the welding current / welding voltage is simply corrected, a breakage / fusion failure will occur and a welding defect will occur.

Further, as a similar method, Japanese Patent Publication No. 3-61
There is a method described in Japanese Patent No. 543. This is described as a correction method for the voltage fluctuation and the waveform distortion on the primary side of the welder as an effect, but this method also detects the welding voltage of the secondary side on the welder side, Kaihei 3-8
The same problem as No. 6376 occurs. Therefore, the object of the present invention is whether the welding current value / welding voltage value changes due to the voltage fluctuation on the primary side of the welding machine, or whether the welding current value / welding voltage changes due to the gap / temporary attachment due to the shape of the work. The welding current value and welding voltage value due to the fluctuation of the primary voltage of the welding machine, the fluctuations of the welding current and welding voltage are corrected, and the welding current and welding voltage are held constant. It is an object of the present invention to provide an arc welding method and an arc welding robot that obtain a good welding effect.

[0005]

In the arc welding method of the present invention, a plurality of primary side voltages on the side of a welding machine are set, and a welding current command value and a welding voltage command value are variously set at each of the primary side voltages. The welding current value and welding voltage value are detected differently, and the relationship between the obtained welding current command value and welding current value and the relationship between the welding voltage command value and the welding voltage value are stored, and during actual welding, the welding machine side When the primary side voltage fluctuates, a desired welding current value, a welding current command value for the welding voltage value, and a welding voltage command value are obtained from the relationship corresponding to the changed primary side voltage, and the welding current command value is obtained. , The welding current command value and the welding voltage command value are changed to the welding voltage command value.

Further, the arc welding robot of the present invention obtains the relationship between the welding current command value and the welding current value and the relationship between the welding voltage command value and the welding voltage value at a plurality of primary side voltages of the welding machine, and the relationship is obtained. Is stored in the storage unit, and when the primary side voltage on the welding machine side fluctuates during actual welding, a desired value is obtained from the relationship stored in the storage unit and corresponding to the changed primary side voltage. Means for determining a welding current command value, a welding current command value for the welding voltage value, and a welding voltage command value, and changing the welding current command value and the welding voltage command value to the welding current command value and the welding voltage command value are provided.

[0007]

When welding, at least two kinds of primary side voltages on the side of the welding machine are set, the primary side voltage value is detected, and the welding current value / welding voltage value at the time of the primary voltage is set. The welding current command value from the robot to the welding machine at that time
Obtain and store each relationship with the welding voltage command value,
After that, the welding current command / welding voltage command to the welding machine is changed from the stored relationship with respect to the fluctuation of the primary side voltage of the welding machine during actual welding, and the welding is performed to perform welding. Even if the welding current value / welding voltage value fluctuates due to the fluctuation of the primary side voltage of the machine, the fluctuation amount of the welding current / welding voltage is corrected,
Good welding results can be obtained by keeping the welding current value and the welding voltage value constant.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is an embodiment of the present invention and is a schematic configuration diagram of a welding machine and an arc welding robot. The primary side voltage of the welding machine 1 (three-phase 200 V in this case) is converted into a secondary side voltage by the transformer 5, then converted into a DC voltage by the voltage converter 6, smoothed by the LPF 9, and A / D converted. It is converted into a digital signal by the device 12 and input to the robot controller 2. The welding machine 1 is provided with a current detector 7 and a voltage detector 8 for detecting a current I _W flowing between the torch 3 and the jig 4 and a voltage V _W between the torch 3 and the jig 4. The welding current I _W detected by the current detector 7 is smoothed by the LPF 10, converted into a digital signal by the A / D converter 13, and input to the robot controller 2. Similarly, the voltage detector 8
The welding voltage V _W detected in 1 is smoothed by the LPF 11, converted into a digital signal by the A / D converter 14, and input to the robot controller 2.

The robot controller 2 uses the welding current command I
_COM , welding voltage command V _COM , welding start / end command ARC
_A welding current command value I for the CPU 15 that outputs _{ON / OFF} , the storage unit 16, and the plurality of primary-side voltages V on the welding machine 1 side
The relational expression between _COM and welding current I _{W and} the relational expression between welding voltage command value V _COM and welding voltage V _W are obtained and stored in the storage unit 16, and the primary side voltage V fluctuates during actual welding. Then, the welding current command value I _COM and the welding voltage command value V _COM are recalculated from the relational expressions stored in the storage unit 16 and the CPU
It includes a calculator 17 for outputting to 15. FIG. 2 (1) is a flowchart showing a process of creating a relational expression between the welding current command value and the welding current value and a relational expression between the welding voltage command value and the welding voltage value, which is performed by the calculator 17. First, the primary side voltage V of the welding machine 1 is measured through the A / D converter 12 (step 2
1), welding current command I _COM and welding voltage command V _COM are output, and welding start / end command ARC _{ON / OFF} is turned on (step 22). The welding current value I _W and the welding voltage value V _W at this time are measured through the A / D converters 13 and 14, respectively (step 23). Steps 22 and 23 are repeated several times (step 24), and the obtained relationship between the welding current command value and the welding current value and the relationship between the welding voltage command value and the welding voltage value are stored in the storage unit 16 (step 25). Next, welding machine 1
The above operation is repeated by changing the primary side voltage V (step 26). In this way, the storage unit 16 stores the welder 1
It means that the relational expression between the welding current command value and the welding current value and the relational expression between the welding voltage command value and the welding voltage value at different primary side voltages V are stored.

FIG. 2 (2) shows a calculator 1 at the time of actual welding execution.
It is a flowchart which shows the process of 7. When the primary voltage V of the welding machine 1 fluctuates from a predetermined voltage to V ₁ ,
The voltage V ₁ is detected through the A / D converter 12 (step 31), the storage unit 16 is searched, and a desired welding current value and a welding current command value for the welding voltage value are obtained from the relational expression for the primary side voltage V ₁ . , Find the welding voltage command value (step 3
2) Then, this is output to the CPU 15 (step 33).
Since the CPU 15 outputs these new welding current command and welding voltage command to the welding machine 1 to perform welding, a good welding result can be obtained despite the fluctuation of the primary side voltage V of the welding machine 1.

The above relational expression is actually a data table, and if no data is present, linear welding is performed to obtain a welding current command value and a welding voltage command value. If possible, if the relationship between the welding current value and the welding current command value and the relationship between the welding voltage value and the welding voltage command value are expressed by a function, the above linear interpolation becomes unnecessary.

[0012]

As described above, according to the present invention, whether the welding current value / welding voltage value fluctuates due to the fluctuation of the primary side voltage of the welding machine, the welding current due to the gap / temporary attachment due to the shape of the work・ Identifies whether there is a change in welding voltage and
Corrects the fluctuations in welding current and welding voltage against the fluctuations in welding current and welding voltage due to fluctuations in secondary voltage, and holds the welding current and welding voltage constant to obtain good welding results. be able to.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a welding machine and an arc welding robot in an embodiment of the present invention.

FIG. 2 is a relational expression measurement process (FIG.
It is a flowchart of (1)) and the process (FIG. 2 (2)) at the time of actual welding.

[Explanation of symbols]

1 welding machine 2 Robot controller 3 torch 4 jigs 5 transformers 6 voltage converter 7 Current detector 8 voltage detector 9, 10, 11 LPF (low pass filter) 12, 13, 14 A / D converter 15 CPU 16 Memory 17 arithmetic unit 21-26, 31-33 steps

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Haruki Nakajima Inventor Haruki Nakajima No.2-1 Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture (56) References JP-A-59-16676 (JP, A) JP-A-SHO 59-120372 (JP, A) Actual Kaihei 6-570 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B23K 9/095 B23K 9/12

Claims (2)

(57) [Claims] 1. In an arc welding method in which arc welding is performed by instructing a welding current and a welding voltage from a robot side to a welding machine, a plurality of primary side voltages on the welding machine side are set, and at each of the primary side voltages, Welding current command value and welding voltage command value are variously changed to detect the welding current value and welding voltage value, and the relationship between the obtained welding current command value and welding current value and the relationship between the welding voltage command value and the welding voltage value are shown. If the primary voltage on the welding machine side fluctuates during actual welding, the desired welding current value, the welding current command value for the welding voltage value, from the relationship corresponding to the primary voltage after the fluctuation, An arc welding method comprising: determining a welding voltage command value, and changing the welding current command value and the welding voltage command value to the welding current command value and the welding voltage command value. 2. In an arc welding robot for performing arc welding by instructing a welding current and a welding current to a welding machine, the relationship between the welding current command value and the welding current value at a plurality of primary side voltages of the welding machine, and the welding voltage. Obtain the relationship between the command value and the welding voltage value, store the relationship in the storage unit, in the actual welding,
When the primary voltage on the welding machine side fluctuates, a desired welding current value and a welding current command value for the welding voltage value are stored in the storage unit from the relationship corresponding to the changed primary voltage. An arc welding robot having means for obtaining a welding voltage command value and changing the welding current command value and the welding voltage command value to the welding current command value and the welding voltage command value.