JPH079143A - Arc sensor - Google Patents

Abstract

(57) [Summary] [Purpose] In short arc welding where short circuits occur frequently,
(EN) An excellent arc sensor that can be applied to a wide range of welding conditions by sufficiently obtaining effective and accurate detection data without the influence of a short circuit subsequent current. [Arrangement] Arc sensor signal source detection means (welding current detection means) 1, short circuit determination means 2, area classification method setting means 7, integration area setting means 9, and arc sensor main circuit 9 are provided for rotation. If there is no short circuit during one revolution of the arc, the preset integration area is adopted, and if a short circuit occurs during rotary arc welding, the integration prohibition area is set from the short circuit occurrence area, and any area other than the integration prohibition area is set. The arc sensor is configured to dynamically allocate the integration area of the arc sensor signal source in the area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc sensor effective for consumable electrode type automatic arc welding (hereinafter referred to as short arc welding) performed in a short arc region.

[0002]

2. Description of the Related Art In recent years, the rotary arc welding method in automatic arc welding has not only characteristics such as the effect of uniformizing the melted shape in welding and the flattening of the bead shape, but also the welding current or arc voltage. Since it is suitable for arc sensor control in which the central axis of the nozzle is always located in the center of the groove of the work piece to be welded by the signal obtained from the change, it has begun to be widely applied to automatic welding of thick plates. There is.

When this arc sensor control technique is applied to short arc welding suitable for thin plates, the welding current or arc voltage, which is a signal source, is greatly disturbed by the effect of a short circuit, so that it does not work properly as an arc sensor.
Therefore, as a specific conventional technique for controlling an arc sensor in short arc welding, Japanese Patent Laid-Open No. 3-18479 has been proposed.
The method disclosed in the publication is being tried. The conventional arc sensor disclosed in Japanese Patent Laid-Open No. 3-18479 will be described below with reference to the drawings.

FIG. 4 is a diagram showing an integration region in a short arc welding of a conventional arc sensor, in which the direction of welding progress is indicated by an arrow. FIG. 5 is a block diagram showing control of a conventional arc sensor.

In FIG. 5, reference numeral 11 denotes an arc rotational position detector, which detects the rotational position of the welding torch. 12 is an arc voltage waveform Ea detected for each revolution of the arc, 13
Is a preset reference voltage waveform Eo, and the arc voltage waveform Ea and the reference voltage waveform Eo are respectively the differential amplifier 1
4 is input.

Reference numeral 15 is a switching logic circuit for determining an integration area by inputting signals from the rotational position detector 11 and the integration area setting circuit 16, and 17 is a switch for integrating the left side (L) area of the rotating arc. The differential amplifier 1 operates according to the L area command of the switching logic circuit 15,
Arc voltage waveform difference signal (Ea-E
o) is sent as a plus to the integrator 20. Reference numeral 18 denotes a switch for integrating the right side (R) region of the rotating arc, which is operated by the R region command of the switching logic circuit 15 and is amplified by the differential amplifier 14 to obtain the arc voltage waveform difference signal (E
a-Eo) is made negative by the inverter 19 and the integrator 2
Send to 0. The integrator 20 operates according to the integration region command of the switching logic circuit 15, integrates the signals input through both switches 17 and 18, sends the integrated value difference Sd to the memory 21, and is temporarily stored therein.

On the other hand, a short circuit detection circuit 22 for detecting the presence or absence of a short circuit in the integration area is provided, and the signal Ea of the detected arc voltage waveform 12 and the short circuit detection level setter 23 are set in advance. Short circuit level signal Elo
Input w and short-circuit detection circuit 22,
The presence or absence of a short circuit is determined at. This determination result is sent to the switching logic circuit 15 as a data acceptance / rejection command. The above-described operation of the short circuit detection circuit 22 is performed by the integration area command from the switching logic circuit 15.

When the short-circuit detection circuit 22 determines that an open arc state is occurring during integration by the integrator 20,
Simultaneously with the completion of the integration, the switching logic circuit 15 outputs a reset signal to the memory 21, and almost simultaneously outputs a sample hold signal. As a result, the previously temporarily stored integral value difference Sd is reset, the presently integrated value difference Sd is temporarily stored, and the newly stored integral value difference Sd causes the integral value difference Sd to become zero. As described above, the X-axis controller 24 moves the welding torch in the X-axis direction (that is, the direction orthogonal to the welding proceeding direction).

On the other hand, when the short-circuit detection circuit 22 determines that the short-circuit state occurs during integration by the integrator 20,
Since it is not appropriate to use the arc voltage waveform at that time as a sensor signal source, the previous integration value difference Sd is held as it is without resetting the memory 21, and the integration value difference Sd becomes zero. Thus, the X-axis controller 24 moves the welding torch in the X-axis direction. In this way, if a short circuit occurs during integration, the data cannot be used, so it is desirable to limit the integration region to a position where a short circuit is unlikely to occur.

It is clear that the welding arc length during arc rotation is shortest at the rearmost portion Cr shown in FIG. 4, and there is a high probability that a short circuit will occur at this point for each revolution of the rotating arc. Therefore, in the short arc welding, as shown in FIG. 4, the integration regions 31 and 32 are, for example, 45 to the left and right around the foremost portion Cf of the arc rotation where the short circuit is unlikely to occur.
It is preferable that the angle is in degrees, and generally, the right and left are set to have the same phase angle in the range of 5 degrees to 90 degrees.

As described above, the above-mentioned conventional method adopts the high-speed rotating arc welding to cause the short circuit of the short arc welding to occur periodically at the rear side of the arc rotation in the welding direction, and to determine the integral region of the arc voltage waveform difference signal. Front of arc rotation ± 5 degrees ~
By narrowing it to 90 degrees, the probability that a short circuit will occur in the integration region will be reduced, and if a short circuit occurs in the integration region, the data will not be used to reduce the effect of the short circuit. The control is applied to short arc welding.

[0012]

However, in the above-mentioned conventional method, due to the inductance inserted in the welding current circuit for improving the stability of the arc which is widely used in the short arc welding, the welding is performed even after the completion of the short circuit. Since the current is affected by a short circuit, the integration area cannot be wide,
There is a problem in that the accuracy of the arc sensor deteriorates when the integration area is narrowed.

The present invention solves the above-mentioned problems of the prior art. Even in short arc welding in which short circuits frequently occur by inserting an inductance in a welding current circuit to improve arc stability, an accurate arc sensor is provided. The purpose is to provide.

[0014]

To achieve the above object, an arc sensor according to the present invention comprises an arc sensor signal source detecting means, a short-circuit judging means, a region classification setting means, an integration region setting means, and an arc. An arc sensor equipped with a sensor body circuit. When a short circuit does not occur during one rotation of a rotating arc, a static integration area that is set in advance as the integration area is adopted, and when a short circuit occurs during rotating arc welding. Sets the integration inhibition area from the area where the short circuit occurs,
A dynamic integration area is adopted as an integration area in any area other than the integration prohibition area.

[0015]

According to the above-mentioned means, even in short arc welding in which short circuits frequently occur by inserting an inductance in the welding current circuit to improve the stability of the arc, if there is no short circuit, the static region is integrated, Even if there is a short circuit, an excellent arc sensor capable of sufficiently obtaining effective detection data can be realized by dynamically setting and integrating a region that is not affected by the short circuit.

[0016]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a welding current detecting means such as a current transformer, which outputs a welding current signal as an arc sensor signal source. Reference numeral 2 denotes a short-circuit judging means, which has a short-circuit detecting means 3 for detecting the presence or absence of a short-circuit, a short-circuit strength judging means 4, a short-circuit phase detecting means 5, and a short-circuit number judging means 6.
Reference numeral 7 denotes a static integration region and a section in which a short circuit subsequent current influences (this is referred to as a short circuit influence region), and dynamic integration based on the determination results of the short circuit detection unit 3, the short circuit strength determination unit 4, and the short circuit frequency determination unit 6. Area division method setting means for determining the area setting method, and 8 is integration area setting means, which is a static integration area when there is no short circuit and a dynamic area when there is a short circuit according to the setting method of the area division method setting means 7. The integration area is set and output to the arc sensor main circuit 9. The arc sensor main circuit 9 corresponds to, for example, the conventional arc sensor main circuit shown in FIG. 5, and performs a predetermined integration processing on the welding current signal in the phase shift region determined by the integration region setting means 8 to output the arc sensor output. Get and output.

The operation of the arc sensor composed of the above-described components will be described with reference to FIG. Short circuit due to a short circuit generated in short arc welding The duration of the subsequent current depends on the constants of the welding equipment used such as the inductance of the welding current circuit and the strength of the short circuit.The strength of the short circuit depends on the welding current, arc voltage, etc. Since it is substantially determined by the conditions, it can be considered that the subsequent current duration is almost the same each time when a short circuit occurs when welding is performed under one welding condition. Under the welding conditions in the experiment conducted in this example, the short circuit subsequent current is about 1/6 rotation (60 rpm) of the arc rotation.
Degree) continued.

When there is no short circuit during one rotation, the static integration regions TL and TR are set to the frontmost portion Cf ± 180 degrees in the welding proceeding direction as shown in FIG. 2 (a). As shown in FIG. 2B, assuming that the influence region of the short circuit, 60 degrees, is A, the integration inhibition region includes A ′ which is a symmetric region with respect to the Cf-Cr line (A
+ A ') and the dynamic integration region TL is (TL1' + TL
2 '), the dynamic integration region TR becomes (TR1' + TR2 '). As shown in FIG. 2 (c), when a short circuit occurs a plurality of times during one rotation, if the influence areas of the short circuit are A and B, the integration prohibition area is (A ● B ') + (B ● A'). , The dynamic integration area TL 'is (TL "-(A ● B')), the dynamic integration area T
R'is (TR "-(B ● A ')) However, the number of short circuits in one rotation is large and the dynamic integration regions TL' and TR 'are 0.
When it becomes -10 degrees, the integration area is insufficient and the previous integration value difference is used.

As described above, according to this embodiment, the integration region can be dynamically assigned from the influence region of the short circuit. Therefore, not only when the short circuit does not occur during one rotation of the rotating arc, but also during the one rotation. Even if a short circuit occurs multiple times, the maximum area is integrated among the areas that will not be affected, so it is possible to obtain an arc sensor that does not reduce accuracy and reduces the frequency of data rejection. .

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. The second embodiment is
The welding was performed under two welding conditions. The first welding condition is the same as that of the first embodiment, and the duration of the short-circuit subsequent current is the same as that of the first embodiment, but the second welding condition is that the duration of the short-circuit subsequent current is the arc. About 1 of rotation
Welding conditions of / 4 rotation (90 degrees) are used. Second
When welding under the welding conditions of,
As shown in FIGS. 3 (a) and 3 (b), the static integration region shown in FIG. 2 (a) is used when there is no short circuit during one rotation, and the case where there is a short circuit during one rotation is also set to 0 degree. The dynamic integration regions TL, TR, TL 'and TR' are set in the same way as in the first embodiment. Also, the number of short circuits during one rotation is large and the dynamic integration region TL
If ′ and TR ′ are 0 to 10 degrees, it is assumed that the integration area is insufficient and the previous integration value difference is used.

When the short-circuit strength determination means 4 of the short-circuit determination means 2 determines the strength of the short circuit, the area division method setting means 7 predicts the duration of the short-circuit subsequent current according to the rule stored in advance, and the dynamic integration is performed. It is determined by judging whether the method of FIG. 2 or the method of FIG. 3 is adopted as the section of the area.

As described above, according to the second embodiment, the setting of the subsequent current continuation time of the short circuit and the section of the dynamic integration region are set according to the strength of the short circuit judged by the short circuit judging means 2, respectively. Even if the two welding conditions are used together, an arc sensor having the same accuracy as in the first embodiment can be obtained.

The strength of the short-circuit current may be determined by using the peak value and the rising waveform of the short-circuit current, or only by the peak value depending on the conditions. The setting of the integration region, the section of the dynamic integration region, and the determination range of the integration region shortage is not limited to the specific values shown in the present embodiment, and the number of welding conditions used in combination is three or more. It goes without saying that it is good.

Although the welding current is used as the arc sensor signal source in this embodiment, the same configuration and operation can be realized by using the arc voltage as the arc sensor signal source.

[0026]

As is apparent from the above description of the embodiments, the present invention provides an arc sensor signal source detection means (welding current detection means), a short circuit determination means, a region classification method setting means, and an integration region setting means. And the arc sensor equipped with the arc sensor main circuit, when the short circuit does not occur during one rotation of the rotating arc, the static integration area set in advance is adopted as the integration area, and the short circuit occurs during the rotating arc welding. When the short circuit occurs, the integration prohibition area is set and the dynamic integration area is adopted as the integration area in any area other than the integration prohibition area to improve the arc stability. Even in short arc welding, where short circuits occur frequently by inserting inductance in the current circuit, integration is usually performed over a wide area and narrow only when the short circuit affects a wide integration area. By integrating the frequency, it can realize high accuracy superior arc sensor capable of obtaining a valid detection data sufficiently.

[Brief description of drawings]

FIG. 1 is a block diagram of an arc sensor according to an embodiment of the present invention.

FIG. 2 is a region division diagram in the arc sensor of the first embodiment of the present invention, where (a) shows a range of left and right static component regions, and (b) shows a case where one short circuit occurs during one rotation. Figure (c) showing the range of short-circuit affected area, integral prohibition area, and dynamic integral area (c) shows the range of short-circuit affected area, integral prohibition area, and dynamic integral area when there are multiple short circuits in one rotation. Figure

FIG. 3 is a region sectional view of an arc sensor under a second welding condition according to another embodiment of the present invention, in which (a) shows a short circuit influence region and an integral prohibition region when one short circuit occurs during one rotation; Figure showing the range of the integration area (b) is a figure showing the range of the short circuit affected area, the integration prohibition area, and the dynamic integration area when the number of short circuits is one during one rotation

FIG. 4 is a control block diagram of a conventional arc sensor.

FIG. 5 is a diagram showing an integration area in short arc welding of a conventional arc sensor.

[Explanation of symbols]

1 Welding current detection means (arc sensor signal source detection means) 2 Short circuit determination means 7 Area classification method setting means 8 Integration area setting means 9 Arc sensor main circuit

Claims (2)

[Claims] 1. An arc sensor equipped with an arc sensor signal source detection means, a short circuit determination means, a region classification method setting means, an integration region setting means, and an arc sensor main circuit, wherein one revolution of a rotating arc occurs. If a short-circuit does not occur in, the preset integration area (static integration area) is adopted. An arc sensor that dynamically allocates the integration area (dynamic integration area) of the arc sensor signal source in any area other than. 2. The arc sensor according to claim 1, wherein the short circuit subsequent current duration and the division of the integration region are set according to the strength of the short circuit determined by the short circuit determination means.