JPH072275B2 - Arc welding monitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to an arc welding monitor device for monitoring arc welding.

[Prior Art] Arc welding is a welding method in which an arc is used to heat a material to be welded (base metal) and to perform fusion welding. There is. In arc welding, when a voltage is applied between the welding electrode (arc welding rod) and the base metal, the tip of the welding electrode is heated by arc heat to form droplets and transfer to the base metal surface.

There are three basic types of droplet transfer in arc welding as shown in FIG. FIG. 8 (A) is a clobule transfer type, FIG. 8 (B) is a spray transfer type, and FIG. 8 (C) is a short circuit transfer type. In any case, the arc is stabilized during the welding process, and the droplet transfer is stably repeated, so that the desired welding result is obtained.

Conventionally, a meter relay is known as a device for monitoring arc welding. This device measures, for example, a welding current every 1 second and displays the measured value by a meter.

[Problems to be Solved by the Invention] However, in arc welding, due to a complicated action involving various phenomena such as a pinch effect, a plasma air flow, and magnetic blowing, or fluctuations in a shield gas supply amount, a wire supply speed, and the like. May cause the arc to fluctuate irregularly. Since the meter relay has a slow response speed and monitors only for a certain period of time, it is not possible to correctly capture small arc fluctuations and irregular arc fluctuations.
Further, the meter relay has a drawback that it cannot be used in other arc welders having different droplet transfer characteristics (especially cycle).

The present invention has been made in view of the above problems, and an object of the present invention is to provide an arc welding monitor device that can accurately grasp the situation of arc welding and can be applied to any arc welding machine.

[Means for Solving the Problems] In order to achieve the above object, a first arc welding monitor apparatus of the present invention is an apparatus for monitoring arc welding by an arc welder, in which welding flows between a welding electrode and a base material. A current detecting means for detecting a current, an A / D converter for converting an analog output signal of the current detecting means into a digital signal at a predetermined sampling frequency, and an operation for setting a calculation period and a moving pitch for obtaining a moving average. Period and moving pitch setting means, moving average calculating means for obtaining a moving average of the welding current at the set calculation period and moving pitch from the digital output signal of the A / D converter, and a moving average value of the welding current Monitoring value setting means for setting a monitoring value for monitoring the welding condition, and a welding status or a welding result is determined by comparing the moving average value of the welding current with the monitoring value. And a determination output unit for displaying and outputting the determination result of the determination unit.

A second arc welding monitoring device of the present invention is a device for monitoring arc welding by an arc welding machine, wherein voltage detecting means for detecting an arc voltage between a welding electrode and a base material,
An A / D converter for converting the analog output signal of the voltage detecting means into a digital signal at a predetermined sampling frequency,
A calculation period and a moving pitch setting means for setting a calculation period and a moving pitch for obtaining a moving average;
Moving average calculating means for obtaining a moving average of the arc voltage at the set calculation period and moving pitch from the digital output signal of the converter, and a monitoring value for setting a monitoring value for monitoring the moving average value of the arc voltage. A configuration comprising: setting means; determination means for comparing the moving average value of the arc voltage with the monitoring value to determine the welding status or welding result; and a determination output means for displaying and outputting the determination result of the determination means. did.

Further, in order to carry out highly reliable monitoring, a means for setting a section for monitoring arc welding is provided.

[Operation] FIG. 7 shows waveforms of the droplet transfer cycle and the welding current in the short-circuit transfer type as an example. As can be seen from the figure, the droplet transfer is periodically repeated and the welding current is also periodically changed correspondingly. Therefore, the situation of arc welding can be grasped by monitoring the welding current. However, in arc welding, if the ionosphere (gas) called arc constitutes a part of the welding circuit and the arc fluctuates,
Accordingly, the welding current fluctuates subtly or in small steps, roughly, or irregularly. Therefore, the situation of arc welding cannot be correctly grasped by simply measuring the welding current at regular intervals like the conventional meter relay.

The first device of the present invention solves the above problem by using the moving average method. Therefore, the analog output signal of the current detecting means is converted into a digital signal (data) at a predetermined quantization number and a predetermined sampling frequency by A / D conversion, and the moving average of the welding current is obtained based on this data. According to the moving average, meaningless small fluctuations are removed by obtaining an average value for a fixed number of data included in a predetermined calculation period, and substantial fluctuations are ensured by moving the calculation period at a predetermined pitch. Can be captured in. From the moving average value of the welding current thus obtained, the situation or result of arc welding can be correctly grasped.

The second device of the present invention performs the same process as above on the arc voltage instead of the welding current. Since the welding current and the arc voltage change in a fixed relationship (usually a reverse phase relationship),
The moving average of the arc voltage is obtained, and the moving average value can be used to correctly grasp the situation or result of arc welding.

Further, the characteristics of arc welding, particularly the droplet transfer cycle, differ depending on the model or model of arc welding machine. For such variations between welding machines, by selecting the moving average calculation period and moving pitch to appropriate values, it is possible to perform moving average processing optimized for each welding machine, and to keep the accuracy constant. High moving average data is obtained.

Generally, in arc welding, a pilot (trigger) arc is generated immediately after the start of energization, and the arc is gradually extinguished while it is about to end. Since the arcs just before the start and just before the end are not involved in the actual welding, if the judgment is made even in these periods, there is a possibility that a false judgment is made and a malfunction occurs. Therefore, by setting the monitoring section to a meaningful (effective) period, highly reliable determination can be performed.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

FIG. 1 shows the overall configuration of an embodiment in which the arc welding monitor device of the present invention is applied to a DC arc welding machine. This DC arc welding machine applies a DC voltage between the welding electrode (welding wire) 14 and the base metal 16 on the welding torch 12 side of the power supply device 10, and performs MIG welding or MAG welding by the gas shield arc welding method.
Weld. Between the welding wire 14 and the base metal 16, an arc is generated in an atmosphere of a shielding gas such as an inert gas or carbon dioxide gas, and the consumable welding wire 14 is melted and the base metal 16 side at a predetermined speed. Will be sent to.

Regarding such an arc welder, the arc welding monitor device of the present embodiment is provided with means for detecting the arc voltage and the welding current.

Welding wire 14 and base metal to detect arc voltage
Two input terminals of the voltage detection circuit 18 are connected to 16 respectively. The output terminal of the voltage detection circuit 18 is connected to the input terminal of the A / D converter 20, and the output terminal of the A / D converter 20 is connected to the data input terminal of the CPU 28. Voltage detection circuit 18 during arc welding
An analog output signal representing the arc voltage VC is obtained from the output terminal of the analog output signal is digitalized by the A / D converter 20 with a predetermined number of quantization bits (for example, 8 bits) and a predetermined sampling frequency (for example, 5000 Hz). The signal is converted into a signal, and this digital output signal is input to the CPU 28.

Further, in order to detect the welding current, the power supply device 10 and the base material 22
A current detection coil 22 is attached to the conductor 15 between and, and the output terminal of the coil 22 is connected to the input terminal of the current detection circuit 24. The output terminal of the current detection circuit 24 is connected to the input terminal of the A / D converter 26, and the output terminal of the A / D converter is the CPU.
Connected to 28 data terminals. During arc welding, an analog output signal representing the welding current IC is obtained from the output terminal of the current detection circuit 24, and this analog signal is output by the A / D converter 26 with a predetermined number of quantization bits (for example, 8 bits) and a predetermined sampling. It is converted into a digital signal at a frequency (for example, 5000 Hz), and this digital output signal is input to the CPU 28.

The CPU 28 is connected to the keyboard 30, the ROM 32, the RAM 34, the display device 36, the printing device 38, the external interface 40, etc., and executes the programs stored in the ROM 32 to execute various calculations and controls in the arc welding monitor device. I do.

FIG. 2 is a block diagram of functions related to the CPU 28 in the arc welding monitor device. Data input unit 42, data extraction unit 46, average value calculation unit 48, comparison unit 52, determination unit 54, output unit 56
Is composed of a CPU 28, a ROM 32, and a RAM 34, respectively. The calculation period / moving pitch setting unit 44 and the monitoring value setting unit 50 are composed of a CPU 28, a keyboard 30, a ROM 32, and a RAM 34, respectively. The operation of these functional blocks will be described below with reference to the timing chart of FIG.

The data input unit 42 takes in a series of digital signals (data) having digital values as shown in FIG. 4A from the A / D converter 20 or 26. Data interval t is A /
It is a value corresponding to the sampling frequency in the D converters 20 and 26. In the calculation period / moving pitch setting unit 44, the calculation period and the moving pitch for obtaining the moving average value are set to values T (for example, 500 msec) and δ (for example, 20 msec) corresponding to the arc welding machine. The data extraction unit 46 selects a series of data (FIG. 4 (A)) captured by the data input unit 42 from FIG. 4 (B0), (B1), (B2), (B).
3) As shown in, the calculation period W0, W1, W2,
Extract the data contained in W3 ....

The average value calculation unit 48 uses the data extraction unit 46 for each calculation period W0, W.
Moving average values M0, M1, M2, M3 ... Are obtained for a group of data extracted for each of 1, W2, W3 ... (FIG. 4 (C)). Comparison section 5
2 is each moving average value M0, M1, M2, M3 ...
The upper limit monitoring value U _M and the lower limit monitoring value L from the monitoring value setting unit 50
Compare with _M (FIG. 4 (C)). The determination unit 54 includes the comparison unit 52.
The comparison result is received from L _M ≤ Mi ≤ U _M , "appropriate", and when Mi <L _M , "inappropriate because of lower limit or less", U _M <
If it is Mi, the judgment result is "Not suitable because it is above the upper limit" (Fig. 4 (D)). These determination results are sequentially output from the output unit 56 to the display device 36.

FIG. 3 shows an example of the display panel of the display device 36. When the "appropriate" judgment result is obtained, the lamp 36A lights up,
The lamp 36B is lit when the determination result of "being unsuitable because it is below the lower limit" is obtained, and the lamp 36C is lit when the determination result of "Not suitable because it is above the upper limit" is obtained.

Further, the determination unit 54 collects all determination results for each step (energization), and outputs the determination result (attention signal) of "caution" if the number of "unsuitable" exceeds the set value. In this case, in FIG. 3, the “Caution” lamp 36D of the display device 36 is displayed.
Lights up. A caution signal is also sent to the control unit of the welding machine via the external interface 40. Furthermore, the determination unit 54 outputs the determination result (abnormality signal) of "abnormality" when the caution signal is output the set number of times or more, lights the "abnormality" lamp 36E of the display device 36, and performs necessary measures for the welding machine. (For example, stop welding). The set value used in the determination unit 54 is given from the monitor value setting unit 50. Also, the monitoring value setting unit
A monitoring section for performing determination (monitoring) (for example, start time is 150 msec and end time is 900 sec) is also set in 50.

The processing of the above functional blocks (FIG. 2) is performed by processing the data from the A / D converter 20 (welding current IC detection data) and the data from the A / D converter 26 (arc voltage EC detection data). It is done for both simultaneously or for either. Also, the moving average value M obtained from the average value calculation unit 48
It is also possible to create a moving average value waveform based on 0, M1, M2, ... And print it out from the printing device 38.

FIG. 5 and FIG. 6 show an operation example of the moving average processing of this embodiment. FIG. 5 shows a waveform at a normal time, and FIG. 5 (A) is a waveform diagram of the welding current IC before moving average and the arc voltage EC obtained from the output signals of the voltage detection circuit 18 and the current detection circuit 24. FIG. 6B is a waveform diagram of the welding current IC and the arc voltage EC after moving average obtained from the calculation result of the average value calculation unit 48.
On the other hand, FIG. 6 shows a waveform at the time of abnormality, FIG. 6 (A) is a waveform diagram corresponding to FIG. 5 (A), and FIG. 6 (B) is a waveform diagram corresponding to FIG. 5 (B), respectively. As you can see from these figures,
The fluctuations of the welding current IC and the arc voltage EC during arc welding can be clarified by obtaining the moving average, and the situation or result of arc welding can be determined with high accuracy.

Further, when performing arc welding while feeding the welding torch 12 at a constant speed, it is also possible to identify a defective welding position (position) based on the determination result obtained by the determination unit 54, and display the indexed position. The output may be made from the device 36 or the printing device 38. Further, in the arithmetic processing of the arithmetic unit 48,
It is also possible to use the effective value or the maximum value, the minimum value, or the like as the moving average value for the data within the calculation period, in addition to the mean value between the meanings.

All the data obtained by the processing of the CPU 28 can be printed out from the printing device 38, displayed on the lamp or screen of the display device 36, stored in the RAM 34, or transferred to an external device through the external interface 40. is there. Further, the present invention is applicable not only to the DC arc welder but also to the AC arc welder, and the arc welding method is not limited to MIG and MAG welding, and is also applicable to other methods such as TIG welding and plasma welding. It is possible.

[Advantages of the Invention] The present invention has the following effects by having the above-described configuration.

According to the arc welding monitoring device of claim 1, it is meaningless by calculating the moving average after converting the detection signal (analog signal) of the welding current flowing through the welding electrode and the base metal into a digital signal to obtain data. Such fluctuations can be eliminated, and at the same time, substantial fluctuations can be grasped with certainty, and the situation of arc welding or welding results can be grasped correctly.

Further, according to the arc welding monitor apparatus of claim 1 or 2, the moving average processing optimized for each arc welding machine is possible by setting the moving average calculation period and the moving pitch to desired values. Therefore, various arc welding machines can be used.

According to the arc welding monitor apparatus of claim 3, since the section for monitoring the arc welding can be arbitrarily set, the determination is made only during a period in which the welding is meaningful.
A reliable monitoring function can be guaranteed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment in which an arc welding monitor device of the present invention is applied to a DC arc welding machine, and FIG. 2 is a block showing a configuration of functional blocks related to a CPU of the embodiment. FIG. 3 is a partial front view showing a part of the display panel of the display device of the embodiment, FIG. 4 is a timing diagram for explaining the operation of the functional blocks of FIG. 2, and FIG. FIG. 6 is a waveform diagram in a normal state for explaining the action of the moving average process of the embodiment, FIG. 6 is a waveform diagram in the abnormal state for explaining the action of the moving average process of the embodiment, and FIG. 7 is arc welding. FIG. 8 is a diagram showing a droplet transfer cycle and current characteristics in (short-circuit transfer type), and FIG. 8 is a diagram showing a basic form of droplet transfer in arc welding. 10 …… Arc welding power supply, 12 …… Welding torch, 14 ……
Welding wire (welding electrode), 16 ... Base metal, 18 ... Voltage detection circuit, 20 ... A / D converter, 22 ... Current detection coil, 24 ...
… Current detection circuit, 26 …… A / D converter, 28 …… CPU, 30 ……
Keyboard, 32 …… ROM, 34 …… RAM, 36 …… Display device,
38 …… Printer, 40 …… External interface, 42 …… Data input section, 44 …… Computation period / moving pitch setting section, 46 ……
… Data extractor, 48… Average value calculator, 50… Monitor value setting unit, 52… Comparison unit, 54… Judgment unit, 56… Output unit.

Claims (3)

[Claims] 1. An apparatus for monitoring arc welding by an arc welding machine, comprising: current detecting means for detecting a welding current flowing through a welding electrode and a base metal; and an analog output signal of the current detecting means is a digital signal at a predetermined sampling frequency. An A / D converter for converting to, an operation period for obtaining a moving average and an operation period for setting a moving pitch and a moving pitch setting means, and the operation period set from the digital output signal of the A / D converter And a moving average calculation means for obtaining a moving average of the welding current at a moving pitch, a monitoring value setting means for setting a monitoring value for monitoring the moving average value of the welding current, and a moving average value of the welding current. And a determination output unit for displaying and outputting the determination result of the determination unit by comparing the monitored value with the monitoring value. Arc welding monitoring device, characterized in that. 2. An apparatus for monitoring arc welding by an arc welding machine, wherein voltage detecting means for detecting an arc voltage between a welding electrode and a base metal, and an analog output signal of the voltage detecting means are digital signals at a predetermined sampling frequency. An A / D converter for converting to, an operation period for obtaining a moving average and an operation period for setting a moving pitch and a moving pitch setting means, and the operation period set from the digital output signal of the A / D converter And a moving average calculating means for obtaining a moving average of the arc voltage at a moving pitch, a monitoring value setting means for setting a monitoring value for monitoring the moving average value of the arc voltage, and a moving average value of the arc voltage Determining means for determining the welding status or welding result by comparing with the monitoring value; and determining output means for displaying and outputting the determination result of the determining means. Arc welding monitoring device which is characterized in that. 3. A monitoring section means for setting a section for monitoring arc welding is provided.
Arc welding monitor device described in.