JPS6353908B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control device for an arc welding machine, and in particular to a control device for an arc welding machine that digitizes all central operations of the control device and simplifies the control circuit. be.

A conventional device of this type is shown in FIG. In FIG. 1, 1 is a main transformer, 2 is a semiconductor switching element connected to the secondary output of the main transformer 1, and 3 is a shunt, which is connected in series to the welding machine output circuit. 4 is an ammeter and shunt 3
connected to the output of 5 is a voltmeter connected in parallel to the welding machine output. 6 is a control circuit for controlling the welding machine. 6a is a drive circuit for issuing a switching command to the semiconductor switching element 2, 6b is a sequence circuit for instructing the welding order, and 6c is a preflow timer, which outputs a time-up signal to the sequence circuit 6b when the required time has elapsed. 6d is an afterflow timer, and when a predetermined time elapses, the sequence circuit 6
Outputs a time-up signal to b. 7 is a preflow setting device, and the setting output of this device is inputted to a preflow timer 6c. 8 is an afterflow setting device, and this setting output is inputted to an afterflow timer 6d. Reference numeral 9 denotes a trigger switch that gives commands to start and stop welding, and these commands are input to the sequence circuit 6b. 10
is a solenoid valve that controls outflow and stop of the shielding gas, and is connected to be driven by the output of the sequence circuit 6b. 6e is a waveform shaping circuit whose operation start/stop is controlled by a sequence circuit 6b, the output of which is supplied to the drive circuit 6a as an output reference signal. 11 is a pulse width setter, and this set value is input to the waveform shaping circuit 6e. 6f is a wire feed motor drive circuit, and its operation is started and stopped in response to an output command from the sequence circuit 6b. 12 is a pulse frequency setter, and this set value is input to the waveform shaping circuit 6e and the wire feeding motor drive circuit 6f. A wire feeding motor 13 is connected to be driven and stopped by a wire feeding motor drive circuit 6f. A wire 14 serves as an electrode for generating a welding arc in this conventional example, and a wire reel 15 has the wire 14 wound around it. 16 is a power supply chip for supplying one polarity side output of the welding machine output to the wire 14. A roller 17 is mechanically connected to rotate in synchronization with the rotation of the wire feed motor 13, and the wire 14 is fed by the rotation of the roller 17. 18 is a workpiece connected to the other polarity side of the output of the welding machine.

Incidentally, a specific configuration of the conventional circuit diagram shown in FIG. 1 is shown in FIG. 2. That is, the main transformer 1 is composed of a transformer and a rectifier circuit, the semiconductor switching element 2 is composed of a power transistor, the drive circuit 6a is opened and closed by a DC source, a transistor Tr, a photocoupler PC, and a contact, and the sequence circuit 6b is composed of a relay and a rectifier circuit. The preflow timer 6c and afterflow timer 6d are composed of a capacitor, a resistor, and a relay contact. The waveform shaping circuit 6e is composed of a PUT, a capacitor, a resistor, and a flip-flop (F/F). , wire feeding motor drive circuit 6f includes an amplifier (AMP), PUT, pulse transformer (PT), contacts,
It consists of a resistor and a capacitor.

Next, the operation will be explained. First, when the trigger switch 9 is turned on, the signal is transmitted to the sequence circuit 6b and the solenoid valve 10 is operated. As a result, shielding gas flows out between the workpiece 18 and the tip of the wire 14. And preflow setting device 7
When the time limit set by has elapsed, a time-up signal is transmitted from the preflow timer 6c to the sequence circuit 6b, and an operation command is input from the sequence circuit 6b to the drive circuit 6a. Also, at the same time as this operation command, the wire feeding motor drive circuit 6
An operation command is also input to f from the sequence circuit 6b.
As a result, the semiconductor switching element 2 is switched on and the wire feed motor 13 rotates, causing the rotor 17 to rotate. The wire 14 wound around the wire reel 15 is fed toward the workpiece 18 by the rotational force of the roller 17. When the wire 14 touches the workpiece 18, welding current flows from the main transformer 1, through the semiconductor switching element 2, and further through the power supply chip 16, to the wire 14, the workpiece 18, and the main transformer 1, and welding is completed. transition to the state. The welding current at this time is detected by the shunt 3 and displayed on the ammeter 4. on the other hand,
The welding voltage is displayed by a voltmeter 5. Also,
At this time, the waveform of the welding current is determined by the output reference signal that is the output of the waveform shaping circuit 6f. Further, the wire feeding speed is determined by the setting value of the pulse frequency setting device 12. In other words, since it is assumed that one pulse of welding current melts a certain amount of the wire 14, the pulse frequency and wire feeding speed are in a proportional relationship. Such a concept is a known control method for consumable electrode (or wire) type pulse arc welders. Furthermore, the pulse width of the above-mentioned output reference signal can be set to an arbitrary value by the pulse width setting device 11. In this manner, during welding, the wire 14 is fed and welding can be performed with any welding output determined by the waveform shaping circuit 6e (in this case, a pulse waveform was used in the explanation, but direct current may also be used). Next, trigger switch 9
When turned off, a command is issued from the sequence circuit 6b, and first, the wire feeding motor 13 is stopped. Furthermore, after a certain period of time (this is called an anti-stake period), an operation stop command is issued to the drive circuit 6a, and the semiconductor switching element 2 is completely switched off. As a result, the welding arc disappears. Furthermore, when the time limit set by the afterflow setting device 8 has elapsed from the time when the trigger switch 9 is turned off, the afterflow timer 6d times up, and as a result, the operation command to the solenoid valve 10 is stopped, and the shield Gas flow stops;
A series of sequences ends. This is just one example of a welding sequence. Figures a to c show examples of welding sequences.
As shown in the time chart. In the figure, 21 is a trigger switch ON/OFF command, 22 is a solenoid valve operation command, 23 is a drive circuit drive command, and 24 is a wire feeding motor drive command. Also, 25
is a feeding command for filler wire especially in TIG welding. Furthermore, T ₁ is the preflow timed,
By setting this to zero, the shielding gas preflow can be eliminated. Furthermore, _T2 is the afterflow time limit, and by similarly setting this to zero, the afterflow of the shielding gas can be eliminated. T ₃ is the anti-stay time limit. 3a and 3b are typical sequences in the case of a consumable electrode type, and FIG. 3c is an example of a typical sequence in the case of using a filler wire with a non-consumable electrode. In this way, welding machine control circuits have different output waveforms and sequences depending on the model and purpose of use, and in order to accommodate these, it is necessary to use many electronic components and form a large-scale control circuit. Ta. As a result, the cost was quite high, and the reliability was poor due to the use of many parts.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and digitally operates the main parts of the control circuit, that is, the sequence circuit, preflow timer, afterflow timer, and waveform shaping circuit. The aim is to provide a small and inexpensive control device for arc welding machines that can be used commonly for all semi-automatic welding machines by incorporating it into an IC.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a circuit diagram showing an embodiment of the present invention. In the figure, numeral 31 is a digital IC that performs the functions of the sequence circuit, proflow timer, afterflow timer, and waveform shaping circuit display circuit already described in the prior art. Built-in. Note that the preflow timer function, afterflow timer function, and sequence circuit function are collectively referred to as a welding sequence circuit hereinafter. 32 is a first A/D converter that converts the setting value of the pulse frequency setter 12 into a digital quantity and inputs it to the digital IC 31. 33 is a second A/D converter which converts the set value of the pulse width setter 11 into a digital amount and inputs it to the digital IC 31. Further, 34 is a digital preflow time setter, which inputs a set value to the digital IC 31. Furthermore, 35 is a digital afterflow setting device, which also inputs setting values to the digital IC 31. 36 is a first digital light emitting display device, and 37 is a second digital light emitting display device. Reference numerals 38 and 39 are third and fourth A/D converters, respectively, which convert the welding current and voltage into digital quantities. The same reference numerals as in FIG. 1 indicate the same or corresponding parts.

Further, a detailed circuit of the embodiment circuit shown in FIG. 4 is shown in FIG.

Next, the operation of the circuit shown in FIG. 4 will be explained. First, when the trigger switch 9 is turned on, the command is transmitted to the digital IC 31, which issues a command to B to flow the shielding gas.
And digital preflow time setting device 34
When the time limit set by has elapsed, an operation command is input from the digital IC 31 to the drive circuit 6a. Simultaneously with this command, an operation command is also input to the wire feeding motor drive circuit 6f. As a result, the command A is output from the drive circuit 6a to produce a welding output, and the command B is output from the wire feed motor drive circuit 6f to perform wire feeding.
Furthermore, the waveform of the welding current is determined by the pulse frequency setting device 1.
2, the first A/D converter 32
The pulse frequency is determined through the pulse width setting device 11, and the pulse width is determined through the second A/D converter 33 according to the setting value of the pulse width setter 11. The pulse frequency and pulse width commands are transmitted from the digital IC 31 to the drive circuit 6a as output reference signals to determine the welding current waveform. Next, the current and voltage during welding are converted into digital quantities through the third A/D converter 38 and the fourth A/D converter 39, respectively, and are input to the digital IC 31. As a result, the welding current is displayed as a digital value on the first digital light emitting display device 36 and the voltage is displayed as a digital value on the second digital light emitting display device 37 according to each value.

Next, when the trigger switch 9 is turned off, a command is issued from the digital IC 31, first the wire feeding is stopped, and then after a certain period of time the drive circuit 6
An operation stop command is issued to a, the welding output is stopped, and the welding arc is extinguished. Further, when the time limit set by the digital afterflow time setting device 35 has elapsed from the time when the trigger switch 9 is turned off, the outflow of the shielding gas is stopped and the welding sequence circuit function is stopped.

Next, the operation of this embodiment will be briefly explained using the detailed circuit diagram shown in FIG.

First, when the trigger switch 9 is turned on to start welding, the solenoid valve 10 is activated through the OR circuit _OR2 .
At the same time, the counter CNH ₁ is reset using the inverter.
Goes to low level through INV ₁ . As a result, the pulses of clock generator CLK are counted as counter CNT ₁
starts counting. When the counted number matches the digital setting value (0 to 16) of the digital preflow time setter 34, the counter CNT ₁ outputs a high level signal, and as a result, the AND circuit AND
gives a match signal. This output passes through the OR circuit OR ₁ and the inverter INV ₂ , switches off the transistor Tr ₁ of the drive circuit 6a, and a power output can be obtained. The output of the AND circuit AND switches off the transistor Tr ₂ of the wire feeding motor drive circuit 6f through the inverter INV ₃ . In addition, pulse frequency setting device 1
The set output of No. 2 is passed through the A/D converter 32 and converted into a pulse with a constant period t ₁ . When this pulse sets the flip-flop F/ _F2 , the A/D converter 33 enters the operating state and generates a pulse with a constant period _t2 . As a result, after a certain time period _t2 , the flip-flop F/ _F2 is reset and the output Q becomes low level. Through a series of these operations, the output of flip-flop F/ _F2 can be obtained.

Next, the current value and voltage value are each converted into pulses with a constant cycle by an A/D converter, and then the counter
Counted as CNT ₃ and CNT ₄ . At this time, the pulse output of the clock generator CLK is output from the frequency divider circuit DVD.
As a result, the frequency is lowered, a pulse with a low fixed period is generated, and the pulse is input to the read command terminals of registers ReS ₁ and ReS ₂ . Furthermore, the above pulse is delayed by a certain time period through pulse delay circuits DL ₁ and DL ₂ , and
Resets the contents of counters CNT ₃ and CNH ₄ .
As a result, respective counts are stored in the registers RgS ₁ and RgS ₂ at regular intervals in correspondence with the current value and voltage value. The decoders DEC ₁ and DEC ₂ convert this number into a decimal number, and display the first, second, and third digits on the light emitting display. This allows output current and voltage to be displayed.

Further, when the trigger switch 9 is turned off, the reset of the counter _CNT2 becomes low level and is canceled, and counting starts. As a result, the count is counted up to the set value of the digital afterflow setter 35, and when the counts match, a count match output is generated and the flip-flop F/F ₁ is reset. As a result, after a certain period of time (after flow time), the solenoid valve 10 stops operating.
Shield gas stops. When the trigger switch 9 is turned off, the AND circuit AND immediately stops the output, and immediately stops the welding output and wire feeding.

In this way, extremely small digital
By incorporating the control functions of all semi-automatic welding machines into the IC31, you can select the necessary functions according to the model, and the conventional sequence function,
It is an extremely compact and widely applicable control that covers all waveform shaping functions and also has a display circuit function that allows the welding machine to display the required welding current and welding voltage on a digital light emitting display. elements can be made. In addition, if a digital light emitting device is used instead of a pointer-type ammeter or voltmeter as described above, it can be installed on the printed circuit board of the control circuit, saving man-hours for wiring, and reducing the unit cost of parts. This has the advantage of reducing costs. Furthermore, since digital ICs such as those described above can be obtained at extremely low unit prices, the cost of the control circuit can be reduced.

As described above, according to the present invention, the control functions required for an arc welding machine, that is, the welding sequence function, waveform shaping function, current, and voltage display function, can be achieved.
Digitization allows it to be built into an extremely small digital IC, which simplifies the control circuit, reduces the number of parts used, and improves reliability.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams showing a conventional welding device, FIG. 3 is a time chart for explaining the welding sequence, and FIGS. 4 and 5 are welding according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a control circuit of the machine. 6...Control circuit, 6a...Drive circuit, 6f
...Wire feeding drive circuit, 9...Trigger switch, 31...Digital IC. In addition, in the figure,
The same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A trigger switch that generates welding start and stop signals, a preflow time setting device that digitally sets the time for supplying shielding gas to the welding area before the welding output is generated, and after the welding output stops. an afterflow time setting device that digitally sets the time for supplying shielding gas to the welding area; a pulse frequency setting device that sets the pulse frequency of the welding output; and a first device that converts the signal from the pulse frequency setting device into a digital signal. An A/D converter, a pulse width setting device that sets the pulse width of the welding output, a second A/D converter that converts the signal from the pulse width setting device into a digital signal, a welding wire or a workpiece, and a power source. a drive circuit that controls opening and closing of a semiconductor switching element connected between the two, a controller that controls outflow and stop of the shielding gas to the welding area, and a drive device that feeds the welding wire toward the workpiece. a wire feeding drive circuit that drives the welding start signal from the trigger switch, a shielding gas supply circuit that operates the controller to cause the shielding gas to flow out based on the welding start signal from the trigger switch, and a shielding gas supply circuit that causes the shielding gas to flow out after the time set by the preflow time setting device has elapsed. a first detection circuit for detecting that the
The detection signal of the detection circuit causes the first and second A/
a drive circuit drive signal output circuit that outputs a signal to drive the drive circuit based on the signal from the D converter; and a wire feeder that outputs a signal to drive the wire feed drive circuit based on the detection signal of the first detection circuit. a signal output circuit, a second detection circuit that detects that the set time of the afterflow time setting device has elapsed after detecting the welding stop signal from the trigger switch, and a detection signal of the second detection circuit that controls the controller. A control device for an arc welding machine comprising a digital IC having a shield gas stop circuit that activates the shield gas and stops the shield gas. 2. The control device for an arc welding machine according to claim 1, wherein the first detection circuit is constituted by a counter circuit and a clock. 3. The control device for an arc welding machine according to claim 1, wherein the second detection circuit is constituted by a counter circuit and a clock.