JPH0484673A - Arc welding monitoring device - Google Patents

Abstract

PURPOSE:To accurately grasp an arc welding state and to monitor optional arc welding by detecting a welding current flowing through a welding electrode and base metal and determining the welding state or a welding result based on a moving average value of this welding current obtained by an arithmetic means. CONSTITUTION:In a DC arc welding machine, the DC voltage is impressed on between the wedding electrode (welding wire) 14 at the welding torch 12 side from an arc welding power unit 10 and the base metal 16 and MIG welding or MAG welding is performed by a gas shielded arc welding process. During this arc welding, an arc voltage signal is inputted to a CPU28 via an A/D converter 20 from an output terminal of a voltage detection circuit 18. Meanwhile, a welding current signal is inputted to the CPU28 via an ADD converter 26 from an output terminal of a current detection circuit 24. This CPU28 carries out various operations and controls in this arc welding monitoring device by executing a program stored in a ROM32. Those variations can be elucidated clearly and in its turn, the arc welding state or the wedding result can be determined with high accuracy by obtaining the moving average for the welding current IC and the arc voltage EC during arc welding.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arc welding monitor device for monitoring arc welding.

It was to be displayed in the evening.

[Prior Art] Arc welding is a welding method that uses an arc to heat and fusion weld materials to be welded (base metal), and is used for ships and buildings.

It is widely used in the processing of automobiles and various electrical and electronic products.In arc welding, when a voltage is applied between the welding electrode (arc welding rod) and the base material, the tip of the welding electrode is heated by arc heat. The droplets then move onto the surface of the base material.

There are three basic forms of droplet transfer in arc welding, as shown in FIG. Figure 8 (A) is clobule transfer type, Figure 8 (B) is spray transfer type, Figure 8 (C
) is a short-circuit transfer type. In any case, during the welding process, the arc is stable and the droplet transfer is repeated stably.
The desired welding result can be obtained.

Conventionally, a meter relay is known as a device for monitoring arc welding. This device measures the welding current every second, for example, and prints the measured value. [Problems to be Solved by the Invention] However, in arc welding, various phenomena such as pinch effect, plasma airflow, and magnetic blowing are involved. The arc may fluctuate irregularly due to complex effects or due to variations in the amount of shielding gas supplied, the wire feeding speed, etc. Meter relays have a slow response time and only monitor at regular intervals, making it impossible to accurately detect small or irregular arc fluctuations.

Another drawback of meter relays was that they could not be used with other arc welders that had different droplet transfer characteristics (particularly cycles).

The present invention has been made in view of such problems, and an object of the present invention is to provide an arc welding monitor device that can accurately grasp the arc welding situation 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 device of the present invention includes a current detection means for detecting a welding current flowing through a welding electrode and a base metal, and this current detection means. an A/D converter that converts the analog output signal of the A/D converter into a digital signal; a calculation means that calculates a moving average of welding current from the digital output signal of the A/D converter; or a determination means for determining the welding result.

Further, the second arc welding monitor device of the present invention includes a voltage detection means for detecting the arc voltage between the welding electrode and the base metal, and an A/D converter for converting the analog output signal of the voltage detection means into a digital signal. , a calculation means for calculating a moving average of the arc voltage from the digital output signal of the A/D converter, and a determining means for determining the welding condition or welding result based on the moving average value of the arc voltage.

Furthermore, in order to deal with variations in arc welding characteristics between arc welding machines, the present invention is configured to include means for setting a moving average calculation period and a moving pinch.

In addition, in order to perform highly reliable monitoring, a configuration is provided that includes means for setting an interval for monitoring arc welding.

[Operation] FIG. 7 shows, as an example, the droplet transfer cycle and welding current waveform in the short-circuit transfer type. As can be seen from the figure, the droplet transfer is repeated periodically, and the welding current also changes periodically accordingly. Therefore, the status of arc welding can be grasped by monitoring the welding current. However, in arc welding, the ionosphere (gas) called the arc forms part of the welding circuit, and if the arc fluctuates, the welding current changes accordingly, either subtly/small steps or roughly/irregularly. Therefore, if you simply measure the welding current at regular intervals like a conventional meter relay,
It is not possible to accurately grasp the arc welding situation.

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 detection means is converted into a predetermined quantization number by A/D conversion.
Digital signal (data) at a given sampling frequency
Based on this data, calculate the moving average of the welding current. According to moving average, meaningless small fluctuations are removed by calculating the average value for a certain 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 The situation or result of arc welding can be accurately grasped from the moving average value of the welding current obtained in this way.

The second device of the present invention performs the same process as above for arc voltage instead of welding current. Since the welding current and arc voltage change in a fixed relationship (usually an antiphase relationship),
A moving average of the arc voltage is obtained, and the arc welding situation or result can be accurately understood from the moving average value.

Further, the characteristics of arc welding, particularly the droplet transfer cycle, differ depending on the type or type of arc welding machine. To deal with such variations between welding machines, by selecting appropriate values for the calculation period and moving pitch of the moving average, it is possible to perform moving average processing that is optimized for each welding machine, and to always maintain accuracy. High moving average value data can be obtained.

Furthermore, in general, in arc welding, a pilot (trigger) arc is emitted immediately after the start of energization, and the arc is gradually weakened and extinguished just before the end of energization. Since such arcs just before the start and just before the end are not involved in actual welding, if a judgment is made even during these periods, an erroneous judgment will be made, which may lead to malfunction. Therefore, by setting the monitoring interval to a meaningful (effective) period, highly reliable determination can be made.

[Embodiment] The present invention will be described in detail 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 a welding electrode (welding wire) 14 on the welding torch 12 side from a power supply 10 and a base metal 16, and performs MIG welding or MAG welding by a gas shielded arc welding method. . Welding wire 14 and base material 16
An arc is generated in an atmosphere of shielding gas made of inert gas or carbon dioxide gas, etc., and the consumable welding wire 14 is melted and fed to the base metal 16 side at a predetermined speed. It has become.

Regarding such an arc welding machine, the arc welding monitor device of this embodiment includes means for detecting arc voltage and welding current.

In order to detect the arc voltage, two input terminals of a voltage detection circuit 18 are connected to the welding wire 14 and the base metal 1θ, respectively. The output terminal of the voltage detection circuit 18 is connected to the A/D converter 2.
The output terminal of the A/D converter 20 is connected to the data input terminal of the CPU 28. During arc welding, the arc voltage VC is detected from the output terminal of the voltage detection circuit 18.
An analog output signal representing .
(eg, 8 bits) and a predetermined sampling frequency (eg, 5000 Hz), and this digital output signal is input to the CPU 28.

Further, in order to detect the welding current, a current detection coil 22 is attached to the conductor 15 between the power supply device 10 and the base material 22, and the output terminal of this 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.
The output terminal of the converter is connected to the data terminal of CPU 28. 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 converted to a predetermined quantization bit number (
For example, 8 bits) and a predetermined sampling frequency (for example, 5000 Hz) are converted into a digital signal, and this digital output signal is input to the CPU 28.

The CPU 28 uses the keyboard 30. ROM32゜RAM3
4. Display device 36. By connecting to the printing device 38, external interface 40, etc. and executing programs stored in the ROM 32, various calculations and controls in this arc welding monitor device are performed.

Figure 2 shows the CPU 28 in this arc welding monitor device.
This is a block of related functions. Data input section 42.
Data extraction unit 46. Average value calculation unit 48, comparison unit 529 determination unit 54. The output section 56 is the CPU 28 and the ROM 3, respectively.
2 and RAM34. The calculation period/movement pitch setting section 44 and the monitoring value setting section 50 are connected to the CPU 2, respectively.
8, a keyboard 30, a ROM 32, and a RAM 34. The actions of these functional blocks will be explained below with reference to the timing diagram of FIG.

The data input section 42 takes in a series of digital signals (data) having digital values as shown in FIG. 4(A), for example, from the A/D converter 20 or 26. The data interval t is a value corresponding to the sampling frequency of the A/D converters 20 and 26.

In the calculation period/moving pinch setting section 44, the calculation period and movement pitch for determining the moving average value are set to glT (for example, 500 m5 ec) according to the arc welding machine concerned.
+ δ (for example, 20 m5 ec). The data extraction unit 46 extracts the data shown in FIG.
As shown in (Bl), (B2), (B3)..., calculation periods WO, Wl, W2 . W3...
・Extract the data contained in.

The average value calculation unit 48 receives the calculation periods WO, Wl, W2 . Moving average value M(1, Ml, M2.M3・
... (Figure 4 (C)). The comparison unit 52 calculates each moving average value MO, Ml, M2 . M
3 is compared with the upper limit monitoring value UN and lower limit monitoring value LM from the monitoring value setting section 50 (FIG. 4(C)). The determination unit 54 receives the comparison results from the comparison unit S2, and when LM≦Ml≦UM, it is “appropriate J”, when Mi <LM, it is “unsuitable J because it is below the lower limit”, and when UN<Ml, it is “lower limit”. The judgment result is ``Unsuitable for the following reasons'' (Figure 4-12-(D)). These determination results are sequentially output from the output unit 56 to the display device Kj, 3 (3).

FIG. 3 shows an example of a display panel of the display device 36. "
When a judgment result of ``appropriate'' is obtained, the lamp 36A is lit, and when a judgment result of ``unsuitable because it is below the lower limit'' is obtained, the lamp 36B is lit, and when the judgment result is ``unsuitable because it is below the lower limit''. When obtained, the lamp 36C lights up.

Further, the determination unit 54 totals all determination results for each process (energization), and outputs a determination result of "caution" (caution signal) if the number of "unsuitable" items exceeds a set value. In this case, in FIG.
D lights up. A caution signal is also sent to the control section of the welding machine via the external interface 40. Furthermore, when the judgment unit 54 outputs the caution signal more than a set number of times, it is abnormal.
The determination result (abnormality signal) is output, the "abnormality" lamp 36E of the display device 36 is turned on, and the welding machine is made to take necessary measures (for example, stop welding). The setting value used by the determination section 54 is given by the monitoring value setting section 50. The monitoring value setting unit 50 also includes a monitoring section for judgment (monitoring) (for example, a start time of 150m5ec1 an end time of 900m).
sec) is also set.

The processing of the functional blocks (Figure 2) as shown in the following is performed by A/D.
Data from converter 20 (detection data of welding current IC)
, the data from the A/D converter 26 (detection data of arc voltage EC) simultaneously, or one of them.

In addition, the moving average value MO obtained from the average value calculation unit 48
, Ml, M2. It is also possible to create a moving average value waveform based on . . . and print it out from the printing device 38.

FIG. 5 and FIG. 6 show an example of the operation of the moving average processing of this embodiment. FIG. 5 shows waveforms during normal operation, and FIG. 5(A) shows the voltage detection circuit 18. A waveform diagram of the welding current IC and arc voltage EC before the moving average obtained from the output signal of the current detection circuit 24, and FIG. 5(B) shows the welding current IC after the moving average obtained from the calculation result of the average value calculation section 48. , is a waveform diagram of arc voltage EC. On the other hand, Fig. 6 shows waveforms during abnormal conditions, Fig. 6 (A) is Fig. 5 (A), Fig. 6 (B) is Fig. 5 (B).
) is a waveform diagram corresponding to each. As is clear from these figures, by obtaining moving averages of the welding current IC and arc voltage EC during arc welding, it is possible to clearly clarify their fluctuations, and in turn, it is possible to clearly clarify the fluctuations in the welding current IC and arc voltage EC during arc welding. It 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 determine the welding defective location (position) based on the determination result obtained by the determination section 54.
The indexed location may be output from the display device 36 or the printing device 38. In addition, in the calculation process of the calculation unit 48, it is also possible to use an effective value other than the interpolated average value for data within the calculation period, or use values such as a maximum value and a minimum value as a moving average value.

All data obtained through processing by 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. be. Furthermore, the present invention is applicable not only to DC arc welding machines but also to AC arc welding machines, and is also applicable to other arc welding methods such as TIG welding, plasma welding, etc., as well as MIG and MAG welding. It is possible.

[Effects of the Invention] By having the above-described configuration, the present invention provides the following effects.

According to the arc welding monitor device of claim 1, by converting the detection signal (analog signal) of the welding current flowing through the welding electrode and the base metal into a digital signal and using it as data, and then calculating the moving average, Since highly accurate and useful constant data is obtained, the arc welding situation and welding results can be accurately grasped.

According to the arc welding monitor device of claim 2, accuracy can be improved by converting the detection signal (analog signal) of the arc voltage between the welding electrode and the base metal into a digital signal and calculating the moving average. Since highly useful measurement data is obtained, the arc welding situation and welding results can be accurately understood.

According to the arc welding monitor device of claim 3, by making it possible to arbitrarily set the calculation period and moving pitch of the moving average, it is possible to perform moving average processing optimized for each arc welding machine. Can be adapted to arc welding machines.

According to the arc welding monitoring device of claim 4, by making it possible to arbitrarily set the period for monitoring arc welding, determination is made only in a period that is meaningful for welding.
A reliable monitoring function can be guaranteed.

[Brief explanation of drawings]

Fig. 1 is a small block diagram of 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, and Fig. 2 shows the configuration of functional blocks related to the CPU of the embodiment. FIG. 3 is a partial front view showing the display panel of the display device of the embodiment; FIG. 4 is a timing diagram for explaining the operation of the function program shown in FIG. 2; FIG. 5 is a waveform diagram in a normal state to explain the effect of the moving average processing of the embodiment. FIG. 6 is a waveform diagram in an abnormal state to explain the effect of the moving average process in the embodiment. The figure shows the droplet transfer cycle and current characteristics in arc welding (short-circuit transfer type), and FIG. 8 is a diagram showing the basic form of droplet transfer in arc welding. 10... Arc welding power supply device, 12... Welding torch, 14... Welding wire (welding electrode),
16... Base material, 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...RAMl 3e...Display device,
38...Printing device, 40...External interface, 42...Data input section, 44...Calculation period/movement pitch setting section, 46...Data extraction section,
48... Average value calculation section, 50... Monitored value setting section, 52... Comparison section, 54... Judgment section, 5
6...Output section. Patent applicant Myachi Technos Co., Ltd.

Claims (4)

[Claims] (1) A device for monitoring arc welding by an arc welding machine, comprising a current detection means for detecting a welding current flowing through a welding electrode and a base metal, and an A/D conversion for converting an analog output signal of the current detection means into a digital signal. a calculation means for calculating a moving average of the welding current from the digital output signal of the A/D converter, and a determining means for determining the welding status or welding result based on the moving average value of the welding current. An arc welding monitor device characterized by: (2) A device for monitoring arc welding by an arc welding machine, comprising voltage detection means for detecting arc voltage between a welding electrode and a base metal, and an A/D conversion for converting an analog output signal of the voltage detection means into a digital signal. a calculation means for calculating a moving average of the arc voltage from a digital output signal of the A/D converter, and a determining means for determining a welding condition or welding result based on the moving average value of the arc voltage. An arc welding monitor device characterized by: (3) The arc welding monitor device according to claim 1 or 2, further comprising means for setting a calculation period and a moving pitch of the moving average. (4) The arc welding monitoring device according to any one of claims 1, 2, and 3, further comprising means for setting a section for monitoring arc welding.