JP2568510B2 - Arc welding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an arc welding machine for automatic welding used with a welding robot and a welding jig.

2. Description of the Related Art Conventional arc welding machines for automatic welding have a relatively narrow range of welding speeds of 30 to 80 CPM, and are directly operated by welding workers based on low-speed semi-automatic welding arc welding machines. It has been improved so that the adjustment and operation, for example, the adjustment of the wire feeding amount and welding output, the ON / OFF operation of the torch switch, and the operation of the torch can be performed through a welding robot or a welding jig.

Adjustment of the welding output is performed so that the arc will not be unstable and welding defects will not occur with respect to differences in the wire feed rate, the distance between the torch base materials, the welding position, and the shape of the weld joint. This is performed to set the state of the arc within a proper range.

Therefore, even when performing high-speed welding of 100 CPM or more by automatic welding, the welding output adjustment in the range of semi-automatic welding at a relatively low speed of 30 to 80 CPM is covered.

Problems to be Solved by the Invention As described above, in the conventional example, since the welding output control method in low-speed welding is directly applied to high-speed welding, welding defects such as undercut and humping characteristic of high-speed welding are eliminated. There are problems that easily occur. This problem is inconsistent with the main purpose of automatic welding in which the main purpose is to increase the welding speed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems by configuring a user to easily set an appropriate welding output in high-speed welding.

Means for Solving the Problems In order to solve the above problems, the arc welding machine of the present invention outputs an output control signal in accordance with a welding voltage command signal, a welding current command signal and a welding speed command signal. A welding output control circuit for outputting to the control element, wherein the welding output control circuit, when a welding speed command signal is input when the welding speed is low during semi-automatic welding, the welding output immediately after the short circuit is opened. Output a higher output control signal,
When a welding speed command signal with a welding speed higher than that during semi-automatic welding is input, an output control signal that reduces the welding output immediately after the short circuit is opened is output, or a welding speed command signal when the welding speed is low during semi-automatic welding is output. Outputs an output control signal that increases the rate of decrease in welding output after a short circuit is opened.When a welding speed command signal with a welding speed higher than that during semi-automatic welding is input, the welding output immediately after a short circuit is opened. An output control signal for reducing the reduction rate is output.

Operation Since the output is determined according to the welding speed according to the above configuration, the welding output immediately after the short circuit is opened or the welding output reduction rate after the short circuit is opened can be made appropriate.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a rectifier for rectifying a three-phase AC power supply voltage. The output terminal of the rectifier 1 is connected to the primary winding of the main transformer 3 via the welding output control element 2, and the switching operation of the welding output control element generates a high-frequency voltage in the primary winding of the main transformer 4. I do. The high-frequency voltage generated in the secondary winding of the main transformer 3 is rectified by the rectifier 4, smoothed by the smoother 5, and supplied between the wire 15 and the base material 16 via the output terminal 6.

Reference numeral 22 denotes a robot main body, and a torch 14 is provided at a tip of the arm. Reference numeral 17 denotes a welding robot controller, which includes a welding speed command device 18, a torch switch command device 19, a welding current command device 20, and a welding voltage command device 21. The welding speed command signal output from the welding speed command device 18 is input to the welding output control circuit 9 via the welding speed receiving circuit 10. The torch switch command device output from the torch switch command device 19, the welding current command signal output from the welding current command device 20, and the welding voltage command signal output from the welding voltage command device 21 are transmitted through a command value receiving circuit 22. Is input to the welding output control circuit 9. Numeral 11 denotes a short-circuit arc discrimination circuit for detecting whether a short-circuit state or an arc state is detected by detecting a voltage between the output terminals 6. The output of the short-circuit arc discrimination circuit 11 is input to the welding output control circuit 9. The output of the welding output control circuit 9 drives the wire feed command circuit, which drives and controls the wire feed motor 13 to feed the wire 15. In addition, the output of the welding output control circuit 9 causes the pulse width modulation circuit 8, the driver circuit 7
Are sequentially driven to switch the welding output control element 2.

In the above configuration, the welding output control circuit 9 receives four input signals. That is, the welding speed command signal from the welding speed command device 18 of the welding robot control device 7 is shaped and input by way of the welding speed receiving circuit 10, and the welding speed command signal is also transmitted from the welding current command device 20 and the welding voltage command device 21. A welding current command signal and a welding voltage command signal related to the wire feed amount shaped via the command value receiving circuit 22 are input, and a signal indicating the timing of short-circuit opening is input from the short-circuit discrimination circuit 11.

Here, the shaping by the welding speed receiving circuit 10 and the command value receiving circuit 22 usually means that the input from the robot control device 17 is an analog signal, so that the input stage of the welding output control circuit 9 is
Matching between the input stage of the welding output control circuit 9 and the output stage of the robot controller 17 such as A / D conversion for a digital signal and adjustment of an analog amount for an analog signal. Say.

Now, upon receiving the above input, the welding output control circuit 9
The welding output control characteristic based on the welding speed and the welding output control characteristic based on the welding current command signal and the welding voltage command signal related to the wire feed amount are synthesized. Among them, the welding output control characteristic based on the welding current command signal and the welding voltage command signal related to the wire feed amount has a characteristic that the average value of the welding output increases and decreases according to the wire feed amount and fine adjustment.

On the other hand, regarding the welding output control characteristics by welding speed,
This will be described with reference to FIGS. 2 and 3, which are experimental results of the inventor.

FIG. 2 shows the relationship between the welding output reduction rate after short-circuit opening and the amount of spatter generated in low-speed welding (50 CPM). Note that this is the case of lap fillet welding with a wire diameter of 1.2 mm used in CO ₂ welding. The amount of spatter generated is a large factor that determines the quality of welding both in appearance and in maintenance around the torch, but the larger the rate of decrease in welding output, the smaller the amount of spatter generated and a good welding result can be obtained. This tendency of spatter generation does not change even if the welding speed is increased, but when the welding speed is increased, welding defects characteristic of high-speed welding such as undercut or humping occur, and from a different viewpoint from spatter generation. The quality of welding is determined. FIG. 3 shows the result of experimentally determining this tendency. FIG. 3 shows the case of overlap fillet welding with a wire diameter of 1.2 mm used by CO ₂ welding as in FIG. It is apparent that the limit speed at which undercut or humping does not occur increases as the rate of decrease in welding output after opening a short circuit is small.

As described above, by securing the average value of the welding output determined by the wire feed amount and the fine adjustment input, and increasing or decreasing the welding output reduction rate after opening the short circuit by the welding speed, a good A welding result is obtained.

In addition, increasing the welding output immediately after the opening of the short circuit increases the welding output reduction rate, and conversely, decreasing the welding output immediately after the opening of the short circuit has the same effect as reducing the welding output reduction rate. .

Next, a specific configuration example of the welding output control circuit 9 will be described with reference to FIG. The input discriminating circuit 23 receives two input signals of the input signal from the welding speed receiving circuit 10 and the input signal related to the wire feed amount from the command value receiving circuit 22, and specifies those input signals. For example, when the input signal from the welding speed receiving circuit 10 is input in 4 bits and the input signal relating to the wire feed amount is input in 4 bits, the input discriminating circuit is used.
23 outputs 8 bits. The data read circuit 24 reads data at the address specified by the input determination circuit 23 from the data table 25 written in the storage element. Therefore, the data table contains 8 bits = 256 types of data. The contents of the individual data indicate the welding output reduction rate and the output average value after the short circuit is opened.

The data read out by the data readout circuit 24 is converted into an analog signal by the D / A conversion circuit 25, and together with the fine adjustment input signal converted by the D / A conversion circuit 27, A waveform is input to the pulse width modulation circuit 8 at the next stage.

As described above, the example shown in FIG. 4 shows a configuration in which individual control conditions are written in the data table and are read out according to the input conditions. However, the configuration in which the control conditions are calculated according to the input conditions can be easily realized. it can.

Effect of the Invention As described above, the present invention enables appropriate welding output control for each welding speed, thereby providing a stable welding result from a low speed to a high speed. Moreover,
For the user, there is no need to adjust the control parameters relating to the welding speed, and the setting of the welding conditions is very simple. As described above, the present invention increases the welding speed, increases the production efficiency, secures the welding quality, and can easily perform the work even if it is not an operator skilled in welding. Is very large.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an arc welding machine showing one embodiment of the present invention, FIG. 2 is a characteristic diagram showing a relationship between a welding output reduction rate and a spatter generation amount, and FIG. 3 is a welding output reduction rate and welding speed. FIG. 4 is a characteristic diagram showing a limit relationship, and FIG. 4 is a block circuit diagram showing a specific configuration example of the welding output control circuit in FIG. 9 welding output control circuit, 18 welding speed command device, 20
... welding current command device, 21 ... welding voltage command device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsumitsu Matsumoto 1006 Kadoma, Kadoma Matsushita Electric Industrial Co., Ltd. Hideyuki Koyama 1006 Kazuma, Kadoma City Matsushita Electric Industrial Co., Ltd. (56) References JP-A-56-13068 (JP, A)

Claims (1)

(57) [Claims] 1. An arc welding machine comprising a welding output control circuit for outputting an output control signal to a welding output control element in accordance with a welding voltage command signal, a welding current command signal, and a welding speed command signal. The welding output control circuit outputs an output control signal for increasing the welding output immediately after the short circuit is opened when the welding speed command signal when the welding speed is low during semi-automatic welding is input, and the welding speed is lower than during semi-automatic welding. When a high welding speed command signal is input, an output control signal that reduces the welding output immediately after the short circuit is opened is output, or when a low welding speed command signal is input when the welding speed is semi-automatic, a short circuit is opened. Output control signal that increases the rate of decrease in welding output afterwards, and when a welding speed command signal with a welding speed higher than that during semi-automatic welding is input, the welding output decreases immediately after the short circuit opens. Arc welder and outputs an output control signal be reduced.