JPH07314136A - Consumable electrode type arc voltage automatic control method and controller therefor - Google Patents

Abstract

PURPOSE:To rapidly execute arc voltage instantaneous control by repeating the operation to integrate a difference between arc voltage and control target voltage and outputting the stored count value whenever the prescribed step value is reached so as to change the control characteristic of feeding speed of welding wire. CONSTITUTION:According to this arc voltage control method, whenever an arc voltage is detected, a difference between the detected arc voltage and control target voltage value is integrated (103). When the deviation integrated value is turned to larger than the prescribed plus reference value (105), an up pulse is outputted and added (107), on the other hand, it is turned to smaller, a down pulse is outputted and subtracted (112), the operation to compare the count value to a step value is repeated, whenever the step value is changed, because the speed adjusting command signal (110) corresponding to the step value is outputted and a speed command signal is changed, a feeding speed of welding wire is changed as corresponding to the long term variation of arc voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode type arc voltage automatic control method and its control device.

[0002]

2. Description of the Related Art Generally, in an automatic arc welding machine, in order to keep the arc voltage constant during welding work, the feeding speed of the welding wire is controlled according to the detected arc voltage.
A so-called arc voltage prompt control type wire feed speed control system is provided. As shown in FIGS. 6A to 6C, this wire feed speed control system uses the melting speed of the welding wire as a parameter. It exhibits a control characteristic with a gradient. Therefore, even if the arc voltage fluctuates (which is called short-term fluctuation of the arc voltage), the function of the wire feeding speed control system is sufficiently maintained in the state where the melting speed of the welding wire is within the predetermined range. Although the arc voltage can be maintained and the arc voltage can be maintained constant, the welding wire protrusion length, welding current value, etc. are often changed periodically and over a long period of time. If the melting rate exceeds the specified range, the arc voltage will also change (called a long-term fluctuation of the arc voltage), so uniform welding cannot be performed with the speed control characteristics initially set, and partial welding will occur. There was a problem that the strength of the part decreased.

Therefore, in order to solve this problem, the present applicants have previously proposed an arc voltage automatic control device in Japanese Patent Publication No. 53-4821. As shown in FIG. 7, this automatic arc voltage control device includes a wire feed speed control circuit 103 for controlling the welding wire feed speed by the wire feed motor 102 according to the detected arc voltage, and an arc welding occurrence. The average value of the difference between the arc voltage and the control target value voltage detected during a certain period of time is detected, and when the average value is within a predetermined level, the control characteristic of the welding wire feeding speed being performed is appropriate. If the average value exceeds the predetermined level, the welding wire has fluctuated over a long period of time and it is judged that the control characteristics of the welding wire feed rate are inappropriate, and the welding wire feed rate control is performed. Circuit 103
The control characteristic of the welding wire feeding speed is automatically adjusted so that the average value of the difference is within the predetermined level. Therefore, the voltage dividing circuit 1 is provided.
04, a reference voltage setting circuit 105, a comparison circuit 106, a pulse generation circuit 108, and a voltage division ratio switching device 107 including a reversible counter 109.

Therefore, in such an apparatus, the wire feed rate control circuit 103 can be operated to control the welding wire feed rate in response to short-term fluctuations in the arc voltage, while the welding wire melts. Even for long-term fluctuations in arc voltage due to changes in welding conditions such as speed,
The arc voltage could be controlled to be constant by operating the control characteristic adjusting system.

[0005]

However, in the above-mentioned arc voltage automatic control device proposed above, the average value of the difference between the arc voltage and the control target value voltage is detected for a fixed time (sampling time), and Since it is determined whether the average value exceeds a predetermined level, it takes a certain period of time to sample the difference between the arc voltage and the control target value voltage. When the deviation from the value voltage is large, there is a problem that it takes more time than necessary to stabilize the control and quick response cannot be performed.

Therefore, the object of the present invention is to solve the above-mentioned problems of the arc voltage control device proposed above and to change the protruding length and material of the welding wire. Even if there is a long-term fluctuation in the arc voltage due to factors such as changes in the arc voltage, the control characteristics of the welding wire feed rate can be quickly changed to the optimum one, and the arc voltage rapid response control can be performed appropriately and quickly. It is an object of the present invention to provide a consumable electrode type arc voltage automatic control method and a control device that can be used for other purposes.

[0007]

SUMMARY OF THE INVENTION The consumable electrode type arc voltage automatic control method of the present invention proposed to achieve the above object controls the welding wire feeding speed by the wire feeding motor through the control of the arc voltage. This is an improved arc voltage quick response control method.The following active steps are generated to generate a speed adjustment command signal for correcting the reference speed command signal generated by the welding condition setter according to the control system. It is configured to include.

That is, in the first step, the difference between the detected arc voltage and the control target value voltage set by the set welding condition setter or the like is deviation-integrated, and in the second step, the deviation is obtained. When the integrated value reaches a predetermined plus value, a count pulse is output, the output count pulse is added, the count value is stored and held, and then the integrated value is cleared. When it becomes a negative value, the count pulse is output, the output count pulse is subtracted, the count value at that time is stored and held, and then the integrated value is cleared.

Next, in the third step, when the count value stored and held in the second step reaches a preset predetermined step value, a speed adjustment command signal corresponding to the step value is output. Here, the step value for changing the speed adjustment signal may be changed every time a plurality of count values are counted, but it is changed every time the count values are different by making one-to-one correspondence with the count value of the counter. You may do it.

Further, in the control method of the present invention as set forth in claim 2, the welding in which the count value for changing the speed adjustment command signal is set by the welding condition setter or the like every time the setting of the welding voltage changes. The initial value is preset according to the voltage. Further, in claims 3 to 6,
An arc voltage automatic control device for carrying out the arc voltage quick response control method of the present invention is proposed, and in claim 3,
An improved arc voltage automatic control device of the previously proposed consumable electrode type automatic arc voltage control device has been proposed.In this device, the welding wire feeding speed is preset according to the welding current, welding wire diameter, material, etc. The reference speed command signal that has been corrected is corrected by the speed adjustment command signal, and the speed command signal is input as the control target value signal of the arc voltage quick response control circuit. The arc voltage detected by the voltage detector is compared with the control target value voltage, and the deviation integration circuit that integrates the difference and the integrated output by this deviation integration circuit are
It has a comparison circuit for comparing with a predetermined plus and minus reference value set in advance, and every time an up pulse or a down pulse is output according to the result of the magnitude judgment by the comparison circuit,
A control deviation discriminating circuit that repeats the operation of clearing the integrated output of the deviation integrating circuit, and when the up pulse from the control deviation discriminating circuit is received, the up pulse is added, and when the down pulse is received, the down pulse is added. A counter for storing and holding the result and a speed adjustment for generating a speed adjustment command signal prepared in advance corresponding to the step value each time the count value of the counter reaches a predetermined step value. It has a configuration including a command signal generation circuit.

Further, the consumable electrode type arc voltage automatic control device proposed in claim 4 further comprises a welding current detector by arc welding and a short-circuit detection circuit, and the arc voltage rapid response control characteristic adjusting circuit includes these elements. By the means, it is configured to operate only when an arc occurs. Furthermore, in the consumable electrode type arc voltage automatic controller according to claim 5, the counter is preset to an initial value according to the set voltage each time the welding set voltage is changed. The consumable electrode type automatic arc voltage control device proposed in Item 6 has a configuration in which the arc voltage detector has an effective value calculation circuit for calculating the effective value of the arc voltage.

[0012]

According to the arc voltage automatic control method of the present invention, each time the arc voltage is detected, the difference between the detected arc voltage and the control target voltage value is integrated, and the deviation integrated value is greater than the predetermined plus reference value. When it becomes larger, it outputs an up pulse and adds it, while when it becomes smaller, it outputs a down pulse and subtracts it, and repeats the operation of comparing the count value at that time with the step value, each time the step value changes. Since the speed adjustment command signal is output according to the step value and the speed command signal is changed, the feeding speed of the welding wire can be changed corresponding to the long-term fluctuation of the arc voltage.

When the deviation between the detected arc voltage and the control target value voltage is large, the number of up / down pulse outputs per unit time increases, the rate of change of the count value increases, and the deviation decreases. When this happens, the rate of change of the count value decreases, so that it is possible to quickly respond to fluctuations in the arc voltage (above, claim 1). Further, according to the method of the present invention proposed in claim 2, when the set value of the welding voltage changes, the count value which defines the rising speed of the control of the feeding speed of the welding wire is also set to the optimum count value. Therefore, even more rapid follow-up control is possible.

According to the arc voltage automatic control system of the present invention, the above-mentioned method of the present invention can be efficiently carried out (claim 3). Further, according to the arc voltage automatic control device of the present invention proposed in claim 4, since the arc voltage quick response control characteristic adjusting circuit operates only while the arc is generated and outputs the speed adjustment signal, the arc is generated. The control characteristic of the wire feeding speed is not changed carelessly before starting welding or at the time of short circuit, and there is no loss of control.

According to the arc voltage automatic control device of the present invention as proposed in claim 5, the initial value of the count value is set to a preset value according to the set value of the welding voltage. Each time the set value of the voltage changes, the count value is set to the optimum count value, which enables more rapid follow-up control. Further, according to the device of the present invention proposed in claim 6, arc voltage detection Since the circuit has an effective value calculation circuit for calculating and outputting the effective value of the arc voltage, it can be applied to both AC and DC welding power sources.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Steps 100 to 112 in FIG. 1 show the basic operation of the control method of the present invention with a flowchart. The control method of the present invention uses the arc voltage Va detected by the voltage detector.
And a first step (steps 102 to 104) of performing a deviation integration operation for integrating a deviation from a control target value voltage Vo set by a welding condition setter and the deviation integration value obtained by this deviation integration is predetermined. When the plus / minus reference level of is reached, the up / down pulse is output, the output count pulse is added / subtracted, the count value at that time is stored and held, and then the deviation obtained in the first step The second step of clearing the integrated value (steps 105 to 108, steps 111 to 112) and the welding wire feeding speed were detected by the control target value voltage Vo set by the welding condition setter and the voltage detector. Since the adjustment is made according to the control deviation from the arc voltage Va, the count value held by counting in the second step is a preset predetermined threshold value. Each reach-up value, a third step of generating change the speed adjustment command signal (step 109,
110) and includes the first to third of these.
As a result of the execution of the active step, the speed adjustment command signal is generated corresponding to the long-term fluctuation of the arc voltage.

2 and 3 show an up pulse and a down pulse which are output in accordance with the deviation between the detected arc voltage Va and the control target value voltage Vo in the control method of the present invention and the magnitude of the integrated value of the deviation. It is a figure showing the relation with. Figure 2
In (b), as a result of implementing the control method of the present invention, the arc voltage Va detected by the arc voltage detector is shown in FIG.
As shown in (a), it shows the output state of the up pulse when it gradually increases and rises to the level of the control target value voltage Vo. As shown in FIG.
The larger the deviation between a and the control target value voltage Vo, the greater the number of up-pulse outputs per unit time, and the arc voltage Va.
It can be seen that the output number of the up pulse decreases as the voltage approaches the control target value voltage Vo.

3 (a) and 3 (b) show that as a result of implementing the control method of the present invention, the arc voltage Va detected by the voltage detector gradually decreases and the control target value voltage Vo
It shows how to calm down to the level of. As can be understood from these figures, in the control method of the present invention,
The larger the deviation between the detected arc voltage Va and the control target value voltage Vo, the greater the number of times the up and down pulses are output per unit time, and the greater the change in the count value of the count pulse, the quicker the control. Stabilizes to. Therefore, compared to the previously proposed control device, the control can be stabilized more quickly, but especially in the case that the count value according to the set welding voltage can be preset, the control can be performed more quickly than when the control is started. It becomes possible to control.

FIG. 4 is a system diagram showing a schematic configuration of the automatic arc voltage control device of the present invention. As shown in the figure, the automatic arc voltage control device of the present invention is provided with a motor driver 11
The welding wire feeding motor M is rotationally driven by the welding wire 1
A feedback control system for sending 0 is provided, and this feedback control system responds immediately to the arc voltage for controlling the arc voltage Va detected by the voltage detector 8 constituting the arc voltage detector to a control target value. It has a control circuit A. Reference numeral 14 is a welding condition setter, 17 is a welding reel for feeding the welding wire 10, and 16 is a welding base material. The arc voltage quick response control circuit A includes a voltage detector 8
The arc voltage Va detected by is input as a feedback signal, and the speed command adjustment signal output from the arc voltage responsive control characteristic adjusting circuit B described later is corrected to the reference speed command signal output from the welding condition storage / calculation unit 15. The speed command signal thus generated is input as the control target value signal.

Further, in order to selectively set the welding current, the welding voltage, the welding wire diameter, and the material thereof, the welding condition setting device 1
4, the welding condition storage / calculation unit 15 calculates, calculates, and outputs a reference speed command signal corresponding to the welding condition selected by the welding condition setting unit 14 and a preset value of the counter 3, and A welding voltage reference signal corresponding to the set welding voltage is input to the arc voltage quick response control characteristic adjusting circuit B as a control target value voltage Vo, and a welding current setting signal defined by the welding condition setter 14 is further supplied to the welding power source device. 13 are being supplied. Reference numeral 12 is a short circuit detection circuit for detecting the presence or absence of a short circuit of the welding wire 10 to the base material 16. Here, the reference speed command signal defines an approximate reference value according to the melting speed of the welding wire 10 which is determined by the welding current, the welding wire diameter, the material, etc., and in the control method of the present invention, this reference speed command is used. The signal is sent to the arc voltage quick response control circuit A as a speed command signal with a value corrected by the speed adjustment command signal output from the arc voltage quick response characteristic adjusting circuit B,
The arc voltage Va is feedback-controlled, and the welding wire 10 is fed.

FIG. 5 shows an arc voltage quick response control characteristic adjusting circuit which constitutes a main part of the present invention. This arc voltage quick response control characteristic adjusting circuit B is configured by combining a deviation integrating circuit 1, a control deviation discriminating circuit 2 having comparators 2a and 2b, a counter 3, and a speed adjustment command signal generating circuit 5. Reference numeral 6 is an effective value calculation circuit for calculating the effective value of the arc voltage Va detected by the voltage detector 8, and the arc voltage quick response control characteristic adjustment circuit B
Can be applied to both arc voltage Va of direct current and alternating current.

Here, the deviation integrating circuit 1 includes a voltage detector 8
Arc voltage Va detected in the form of an analog signal by
In accordance with the welding conditions set by the welding condition setter 14, the difference 1c between the welding condition storage operation unit 15 and the welding voltage reference signal sent as the control target value voltage Vo in the form of an analog signal is calculated by the amplifier circuit 1a. After being amplified, the integrating circuit 1b is configured to perform integration, and the deviation integrated value output from the integrating circuit 1b is output to the two comparators 2a and 2b of the control deviation discriminating circuit 2, where a predetermined positive value is added. ， It is judged whether it is a negative reference value or not.

That is, when the integrating operation by the integrating circuit 1b progresses and the deviation integrated value output from the integrating circuit 1b becomes larger than a predetermined plus reference value, the comparator 2a outputs an up pulse to the counter 3 in the subsequent stage. The comparator 2b outputs the down pulse to the counter 3 at the subsequent stage when the deviation integration value becomes smaller than a predetermined minus reference value as the integration operation of the integration circuit 1b is performed. The integrating operation by the integrating circuit 1b is performed until one of the two comparators 2a and 2b outputs an up pulse and a down pulse in this way, and when one of the comparators 2a and 2b outputs an up pulse and a down pulse, The integration circuit 1b is cleared, the deviation integration value is reset to zero, and the deviation between the next arc voltage Va and the control target value voltage Vo is the same as the integration circuit 1b.
And the same operation is repeated thereafter.

In response to such an operation in the deviation integration circuit 1, in the counter 3, the up and down pulses output from the comparators 2a and 2b are calculated by the welding condition storage calculation unit 15 according to the set welding voltage. Is
Since the preset initial value is added or subtracted and the counting result is held, the count value is sequentially counted up and down according to the up and down pulses from the deviation integration circuit 1 and updated. Here, since the counter 3 stabilizes the feeding speed control of the welding wire quickly, when the welding voltage is set by the welding condition setting device 14, the counter 3 automatically sets the initial value according to the set welding voltage. However, when the set voltage is changed while the arc is once generated to perform the welding, the preset may not be automatically performed.

The count value of the counter 3 is sent to the D / A conversion circuit 5a of the speed adjustment command signal generation circuit 5, and here the digital signal output as the count value of the counter 3 is converted again into an analog signal. Is output. This D
The / A conversion circuit 5a may sequentially convert the speed adjustment command signal each time the count value of the counter 3 is different, or the speed adjustment command signal may be changed each time the count value of the counter 3 reaches a predetermined value. May be changed. In this way, the analog signal output from the D / A conversion circuit 5a is added to or subtracted from the reference speed command signal set in the form of an analog signal by the welding condition storage / calculation unit 15 to become a speed command signal, After being amplified by the amplifier circuit 5b, it is sent to the arc voltage quick response control circuit A to drive the motor driver 11.

The arc voltage quick response control characteristic adjusting circuit B having such a configuration is operated when it is confirmed by the detection signals from the current detector 8 and the short circuit detecting circuit 12 that arc welding is occurring. Has become. For this reason,
It has two control contacts Sa and So that are opened and closed by a control signal sent from the sequence circuit 4. With such a configuration, the arc voltage quick response control characteristic adjusting circuit B
Can be operated only when an arc is being generated, and it is possible to prevent accidental operation when the arc is not being generated.

[0027]

According to the control method of the present invention, when the deviation between the detected arc voltage and the control target value voltage is large,
The number of up / down pulse outputs per unit time increases, the rate of change of the count value increases, and when the deviation decreases, the rate of change of the count value decreases. Therefore, it is possible to respond promptly (claims 1 and 2).

Further, according to the arc voltage automatic control apparatus of the present invention, the control method of the present invention can be efficiently carried out, and a long-term arc voltage which cannot be handled by the conventional feedback control system provided with the arc voltage quick response control circuit. Even for fluctuations,
It is possible to respond promptly (claims 1 and 2). According to the apparatus of the present invention proposed in claim 4, since the arc voltage quick response control characteristic adjusting circuit operates only during the occurrence of arc welding, the wire feeding is performed before the start of welding in which no arc is generated or when a short circuit occurs. The control characteristics of speed are changed carelessly,
There is no loss of control.

According to the device of the present invention proposed in claim 5, since the preset value which is the initial value of the count value is set to a preset value in accordance with the set value of the welding voltage, the welding voltage Each time the set value is different, the count value is set to the optimum count value, which enables the quick follow-up control. Further, according to the apparatus of the present invention proposed in claim 6, the arc voltage detection circuit has an effective value calculation circuit for calculating and outputting the effective value of the arc voltage. It is convenient because it can handle both.

[Brief description of drawings]

FIG. 1 is a flowchart showing a control procedure of a method of the present invention.

FIG. 2 is an operation explanatory diagram of deviation integration in the control method of the present invention, showing a change state of the output number of the up pulse when the arc voltage approaches the control target value voltage level by the control method of the present invention.

FIG. 3 is an explanatory diagram of an operation of deviation integration in the control method of the present invention, showing a change state of the output number of the down pulse when the arc voltage approaches the control target value voltage level by the control method of the present invention.

FIG. 4 is a block diagram showing a schematic configuration of an arc voltage automatic control device of the present invention.

FIG. 5 is a block diagram showing a schematic configuration of an arc voltage quick response control characteristic adjusting circuit.

FIG. 6 is a graph showing a relationship between a welding wire feed rate and an arc voltage with a welding wire melting rate as a parameter.

FIG. 7 is a block diagram showing a schematic configuration of an arc voltage automatic control device proposed in Japanese Examined Patent Publication No. 53-4821.

[Explanation of symbols]

 A: Arc voltage quick response control circuit B: Arc voltage quick response control characteristic adjustment circuit 1 ... Deviation integration circuit 2 ... Control deviation determination circuit 3 ... Counter 4 ... Sequence circuit 5 ... Speed adjustment command signal generation circuit

Claims (6)

[Claims] 1. A speed command signal in which a standard speed command signal defined by a welding current, a welding wire diameter, a material thereof, and the like is corrected by a speed adjustment command signal as described below that corresponds to a change in the melting speed of the welding wire. A method for automatically controlling a consumable electrode type arc voltage, characterized in that the feed rate of the welding wire is feedback-controlled, wherein the speed adjustment command signal is a difference between the detected arc voltage and a set control target value voltage. Is integrated, and when the integrated value reaches a predetermined plus value, a count pulse is output, the output count pulse is added, the count value at that time is stored and held, and then the integrated value is cleared. On the other hand, when the integrated value reaches a predetermined negative value, a count pulse is output, the output count pulse is subtracted, and the count value at that time is subtracted. After storing and holding, the operation of clearing the integrated value is repeated, and thus, the operation of integrating the difference between the arc voltage and the control target value voltage is repeated, whereby the stored and held count value is predetermined. Consumable electrode type arc voltage automatic control method so that it is output every time the step value is reached. 2. The consumable electrode type arc voltage automatic control method according to claim 1, wherein the count value is preset to a preset initial value according to a set welding voltage. Electrode type arc voltage automatic control method. 3. A wire feed motor is provided, and the rotation speed of the motor is controlled so that the detected arc voltage matches a set control target voltage, and the feed speed of the welding wire is fed back. In a consumable electrode type automatic arc voltage control device equipped with an arc voltage quick response control circuit for controlling, an arc voltage quick response control characteristic adjustment circuit is added to the arc voltage quick response control circuit. The reference speed command signal selected and set by the welding condition setting device is input as a control target value, which is a speed command signal corrected by the speed adjustment command signal output from the arc voltage quick response control characteristic adjusting circuit. The arc voltage responsive control characteristic adjustment circuit sets the arc voltage detected by the arc voltage detector by the welding condition setter. A deviation integrator circuit for comparing with the control target value voltage and integrating the difference, and a comparator circuit for comparing the integrated output of the deviation integrator circuit with predetermined preset plus and minus reference values are provided. Each time an up pulse or a down pulse is output according to the result of discriminating the magnitude, the control deviation judgment circuit that repeats the operation of clearing the integrated value of the deviation integration circuit and the up pulse from the control deviation judgment circuit are received. Sometimes the up pulse is added, while when the down pulse is received, the down pulse is subtracted and the counter that stores the count value at that time is stored and the count value of this counter reaches a predetermined step value. For each time, the speed adjustment command signal is generated to output the speed adjustment command signal according to the welding value such as the melting speed of the welding wire according to the step value. Consumable electrode type automatic arc voltage control system with live circuit. 4. The consumable electrode type arc voltage automatic control device according to claim 3, further comprising a welding current detector and a short circuit detection circuit, wherein the arc voltage rapid response control characteristic adjusting circuit is provided by the above means. The consumable electrode type arc voltage automatic control device according to claim 3, which is configured to operate only when it is determined that an arc is being generated. 5. The consumable electrode type arc voltage automatic control device according to claim 3 or 4, wherein each time the welding voltage is set, the counter is changed and set to a preset value according to the set voltage. Consumable electrode type arc voltage automatic control device. 6. The consumable electrode type arc according to claim 3, wherein the arc voltage detector has an effective value calculation circuit for calculating an effective value of the arc voltage. Automatic voltage control device.