JPS5987974A - Control device of arc welding machine - Google Patents

Abstract

PURPOSE:To set independently and control exactly output voltage and an output voltage, respectively, by determining the output voltage of a welding power source by reference voltage, controlling a feed speed of a wire, and holding a welding current at a prescribed value. CONSTITUTION:A titled device consists of an output voltage setting device 11, an output current setting device 7, a welding power source 1 for outputting the voltage corresponding to a command signal, a wire feed speed controlling circuit for feeding a consumable electrode wire 4 in accordance with an output of the setting device 7, a storing circuit 12 and an operating circuit 13. Said circuit 12 stores output voltage and current characteristics of the power source 1 in accordance with an output voltage setting signal. Also, said circuit 13 reads out the output voltage and current characteristics stored in the circuit 12, in accordance with combination of an output (er) of the setting device 11 and an output current signal. Subsequently, the output (er) is converted to a value derived by correcting an output voltage variation portion (DELTAer) generated in accordance with an output current, and is supplied as an output voltage command signal of the power source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention maintains the welding current at a predetermined value by setting a reference voltage to determine the welding 'output' voltage of the power source, and by keeping the feeding speed of the consumable electrode wire at the reference value. This relates to arc welding (geometry control device) that determines welding conditions by

In arc welding using a consumable electrode wire, a method is used in which a power source with substantially constant r-positive characteristics is used as the welding power source, and the welding current is determined by feeding the consumable electrode wire at a substantially constant speed. . In this case, the purpose of controlling the welding current is mostly achieved by controlling the wire feeding speed to a constant value, since the welding current is uniquely determined to a value that provides a melting rate commensurate with the wire feeding speed. In addition, even if the distance between the workpiece and welding parts 1 and 1 suddenly changes, the arc force changes, and the wire feeding speed of the welding part 2 changes, the welding current will change from the output of the power supply. The arc length is recovered by making use of the so-called self-control property of the welding power source, in which the arc length is recovered by changing the melt amount according to the pressure/current characteristics.

However, the output voltage tends to decrease as the output current increases, as shown in Figure 1, not only in welding power sources that do not feed back the output voltage, but also in those that use feedback to follow the reference value. It is inevitable that this will happen. Figure 1 shows the output car r of the welding power source.
J:, Ea is plotted on the vertical axis, output 'current lpr is plotted on the horizontal axis, and the output voltage reference signal ('r is shown as a parameter (0 (er2(ers)).As can be seen from the figure, The rate of fluctuation of the output voltage with respect to the change in the output current increases as the output voltage standard becomes more reliable.For this reason, even for the same welding midstream 111r setting, the difference from the output '4 pressure reference signal △■ t4 is different, and the output voltage moves along the two sides of each voltage/current characteristic curve as the welding midstream changes, so the cutting edge voltage deviates from the expected value at each instant during welding.For this reason, Normally, the output voltage is reset at the same time as the welding current set value is changed.For example, in Fig. 1, when changing the current from I+ to I2 (L+ (I2)), 1"" is applied. erl the value
It is necessary to change from er'2 (erl (er'l) to er'2 (er'l) to obtain the original output voltage eQ. In this case, output ``1'' measures pressure, and this measured value becomes the desired value. It is necessary to turn the output voltage setting dial until it returns to the original value.In this way, there is a correlation between the output voltage E2 and the output current Iw based on the characteristics of the power supply, and each can be adjusted independently. If it is set to , the resulting output will be a different value depending on the setting value of the I1υ person.

The above-mentioned current situation is similar to the case where the wire feeding speed is determined by the output current setting value. Even when controlling the rotational speed of the feed motor, a speed error occurs when performing normal feedback control, and this speed error becomes larger as the set speed becomes 1, that is, as the set value of the output current increases. The rate of variation in the rotational speed becomes larger as the value increases, and the rate of variation in the rotational speed appears directly as the rate of variation in the output current. However, the control system itself operates based on the difference between the set value and the motor rotational speed due to its operating principle. Therefore, it is not possible to compensate for this change in output current.

The present invention detects the actual output current IW with respect to the set value it of the output current, obtains the difference (Ir-Iw), and stores the corresponding memory of the wire feeding motor in the direction in which this difference signal decreases. Then, when each part of the output voltage and output current is input, the characteristics corresponding to each part are read out and the reference signal is corrected by these, so that the constant output current and output voltage can be adjusted arbitrarily. This is how it was done.

FIG. 2 is a connection diagram showing an embodiment of the present invention.

In the figure, 1 is the group Ljl'% supplied to the terminal S;
This is a welding power source that outputs an electric current t31H corresponding to the u pressure, and supplies welding power to the welding torch 2 and the workpiece 3.

4 is a consumable upper wire which is passed through the welding torch 2 to the workpiece 3 by a feed roll 6 driven by an electric motor 5.
will be sent towards. 7 is an output current setting device that outputs the welding current as a digital signal; 8 is a 1)/A converter for converting the output of the output current setting device 7 into an analog signal;
9 is a current detector for detecting the output current of the welding power source 1;
0 is a comparator that compares the output of the Q, , A converter 8 and the output of the current detector 9. 11 is the output voltage setter that outputs the output type J as a digital (M Schiller output voltage setting device, 12 is the output voltage setting device that outputs Δii during welding), and the output voltage and current characteristics are recorded for each combination of output voltage and current. [This is the memory circuit b'R, and 13 is the output current setting device 7 and the output voltage setting device]
This is an arithmetic circuit that receives each output of the memory circuit 12 corresponding to each setting value, reads out the answer of the memory circuit 12 corresponding to each set value, and corrects the output signal of the heavy pressure setting device 11.
The arithmetic circuit 13 calculates the output of welding electric current #1, Ichikawa rl, when the flow characteristic shows a linear change as expressed by a simple linear equation as shown in Fig. 1. The storage circuit 12 serves as a correction amount setter for setting the maximum correction amount, and the calculation circuit 13 outputs the output signal of this correction amount setter according to the combination of output voltage setting device 11 and output current setting device 7. Output voltage setter 11
A summing counter can be used that adds to the output signal of . When the output voltage/current characteristics of the welding power source 1 exhibit complicated curved changes, a semiconductor memory circuit is used as the memory circuit 12, and the arithmetic circuit 13 uses the output of the output voltage setting device 11 and the output current setting device 7. A microprocessor programmed to designate a memory location in the memory circuit 12 in accordance with the output of the memory circuit 12, read it out, correct the output signal of the output pressure setter 1, and output the corrected signal may be used. 14 is the arithmetic circuit 1
This is a D/A converter for converting the digital output of No. 3 into an analog signal and supplying it to the S terminal of the welding power source 1 as an output voltage command.

In the embodiment shown in the figure, '((the rotational speed of the machine 5 is
Controlled by the difference between the output of the output current setting device 7 and the output of the forward current detector 9, the feeding speed of the wire 4 is set to obtain a desired output current. At this time, if a normal differential amplifier is used as the comparator 10, an error will occur between the input and output, so if an integrating circuit is used for the comparator to integrate the difference between the input and output signals, there will always be a difference between the input and output. Since the current is corrected until it becomes zero and then stabilized, extremely accurate control of the forward current output is possible. On the other hand, the output C1- of the output voltage setter]1
is determined in the arithmetic circuit 13 according to the stored contents of the memory circuit 12 corresponding to the output of the output current setter. △er corresponding to the output voltage fluctuation shown in Figure 1 is corrected (e
r+Δer> and is supplied to the D/A converter 14 and converted into an analog signal, and then outputted as a command signal and supplied to the welding power source 1. As a result, the welding power #1 Since the output voltage 211 receives a command signal corrected for voltage fluctuations that vary depending on the output current value, the output voltage can be maintained at a desired value completely regardless of the output DC value.

As a result, the output current and output voltage can be set completely independently, making it possible to obtain a control device that is extremely easy to adjust without being influenced by the other, and is highly accurate. can.

In the embodiment shown in FIG. 2, the output of the arithmetic circuit 13 is converted into an analog signal by the 1/A converter 14 and used as a command signal for the welding power source 1, but the welding power source 1 outputs a digital signal. Of course, if the voltage is to be controlled, this single value converter is not necessary. Furthermore, it goes without saying that the entire device can be constructed using a one-gamma analog signal system. Furthermore, there is one that feeds back the output voltage of the welding power source 1, and one that uses the output of the current detector 9 instead of the output of the output current setting device 7 as an output current signal to the arithmetic circuit 13 (however, it is necessary to convert it to a digital signal). ), the comparator 10 is used as a digital signal comparator and the one-chip converter 8 is replaced, and various other modifications are possible. In particular, when using the output signal of the normal current detector 9 as the output sum current signal sent to the arithmetic circuit 13, the output voltage is corrected in accordance with the actual output current, so the output 'small current' is The output voltage command signal is adjusted not only when changing the set value, but also when the output current changes when the arc length changes due to hand shake of the operator operating the welding torch or changes in the surface shape of the workpiece. It is convenient because it is corrected.

As described above, in the present invention, the wire feeding speed is controlled so that the difference between the output current and the output current setting value becomes zero to maintain the output current at a predetermined value, and the output voltage to be used,
The output voltage/current characteristics of the welding power source stored in advance corresponding to the combination of output currents are read out, and the output voltage command signal is corrected according to the stored contents to generate an output 11χ pressure command signal for the welding power source. Therefore, the output voltage and output current can be determined completely independently, and extremely accurate control is possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of output voltage/current characteristics of a welding power source, and FIG. 2 is a connection diagram showing an embodiment of the present invention. 1... Welding power source, 5... Electric motor, 7. Current setting device,
0... Current detector, 10... Comparator, 11... Voltage setter, J2... Memory circuit, 13... Arithmetic circuit. Attorney Hiroshi Nakai Patent Attorney Proceedings (Self-Benef 1) December 171, 1981'' Commissioner of the Patent Office Tono 1, Matter 1'1 Indication Exit J (Japanese Patent Office 198628 Yumi 2, Name of the invention Arc welding (3 Control equipment 3, Person to be amended 1'1 Related Patent application 2-1-11 Tayo, Yodoyo-ku, Osaka (026) Osaka Transformer Co., Ltd. 4F 4, Agent address 〒532 Yodoyo-ku, Osaka City [ηyo 2-1-11 [Contact information telephone (06) 301-1212]
5. Date of amendment order Voluntary 6. Subject of amendment “Drawings” 399-

Claims (1)

[Claims] 1. Output vehicle) A setter, an output current setter, a welding power source that outputs a voltage according to a command signal, and a welding power source that outputs a voltage according to a command signal; A wire feeding speed control circuit that feeds the consumable electrode wire at a speed, and a memory circuit that outputs the output voltage and current characteristics of the welding power source and stores the heavy pressure setting signal according to the feeding speed. The output of the output voltage setting device and the output current signal are input, and the output vehicle pressure/current characteristics stored in the storage circuit are read out according to the combination of both signals, and the output of the output vehicle pressure setting device is set as the output vehicle current. An arc welding machine control device comprising an arithmetic circuit that converts a change in output vehicle pressure that occurs in response to a corrected value and supplies it as an output voltage command signal of the welding power source. 2. The output current signal is 3. The output current signal is an output current signal of the output vehicle pressure setting device. The arc welding machine control device according to claim 1, which is a signal that detects the output signal of the output current setting device and the output current.4. 2. The arc welding machine control device according to claim 1, which is a circuit that determines the wire feeding speed based on a signal obtained by integrating a signal of the difference between the wire feeding speed and the wire feeding speed.