JPH0516940B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a welding machine control device that allows an operator to remotely adjust welding conditions such as welding voltage, welding current, feeding speed of consumable electrode wire, and welding speed.

[Prior art]

When performing arc welding, it is often necessary to change welding conditions due to changes in the welding posture, changes in the shape of the workpiece, etc. Furthermore, in shipyards, ironworks, and the like where large objects to be welded are handled, the installation location of the welding power source and the actual work location are often far apart. In such a case, it would be extremely inconvenient and inefficient to go to the welding power source and switch the welding conditions every time the conditions are changed. Therefore, it is necessary to have a welding condition adjuster at hand so that the operator can adjust the welding conditions to appropriate conditions as necessary. For this purpose, it is necessary for the operator to have at hand a variable resistor corresponding to each welding condition. Conventionally, in such cases, a method has been adopted in which each variable resistor is connected to the welding machine body using a dedicated cable. However, in this case, it is necessary to use multi-core cables, which not only increases the incidence of disconnection accidents, but also significantly impedes work efficiency as it is necessary to route thick cables. It was hot. A technique that improves this conventional technology, that is, a method that does not use a variable resistor connected to a dedicated cable, supplies low-frequency rectangular wave pulses from the output end of the welding power source to the welding torch during welding pauses, and at the welding point. A method has been proposed in which a welding wire is directly or indirectly short-circuited to a workpiece, and welding conditions are set according to the number of pulses during this short-circuiting.

[Problem to be solved by the invention]

The method that is an improvement on the conventional technology described above requires a complex oscillation circuit that generates a low-frequency rectangular wave pulse, and the welding operator has to select the welding conditions and continuously short-circuit the welding torch to the workpiece. “time”
In order to perform operations with an analog recognition, the welding conditions in which the welding operator attempts to continue the short circuit based on the short circuit time predicted by the welder and the time during which the welder actually continues the short circuit. There was a problem in that the welding conditions determined based on the number of output pulses deviated from each other, resulting in an error, and the welding conditions that the welding operator wanted to select were not set.

[Means for solving problems]

The present invention provides a welding control device that connects a workpiece 3 and a welding torch 2 to output terminals a and b of a welding power source 1 and presses a welding start push button switch 7 to start welding. An auxiliary power supply E1 that outputs a low-voltage, small-current DC current that does not generate an arc even when the welding torch and the workpiece are short-circuited and opened, and an auxiliary power supply E1 that outputs a low-voltage, small-current direct current that does not generate an arc even when the welding torch and the workpiece are short-circuited and opened, and the output terminals can be short-circuited for any time and opened for any time. a counting circuit 8 that counts the number of short circuits when the welding operator repeats this a predetermined number of times; A holding command circuit 10 that outputs a holding command signal h that resets the counting number, a memory circuit 9 that stores the counted value using the holding command signal h, and a selection that selects welding conditions based on the output signal of the memory circuit 9. This welding machine control device includes a circuit 5 and a prohibition circuit 6 that prohibits changes in selected welding conditions during welding.

【Example】

FIG. 1 is a block diagram of an embodiment of the invention.
In the figure, reference numeral 1 denotes a welding power source, which supplies, for example, DC power to a welding torch 2 and an object to be welded 3.
8 is a counting circuit that is connected to output terminals a and b of the welding power source 1 and counts the number of short circuits between the output terminals a and b, and a control circuit that determines whether the welding power source 1 is short-circuited or open when welding is stopped. This is an auxiliary power source. Reference numeral 9 denotes a memory circuit that takes in the output of the counting circuit 8 when a hold command signal, which will be described later, is received at the terminal E, and stores it when the input to the E terminal disappears. 10
is a holding command circuit connected in parallel with the counting circuit 8, which issues a holding command to the E terminal of the memory circuit 9 when the output terminals a and b remain open for a relatively long predetermined period of time or more. After supplying the signal h, a return signal c is supplied to the counting circuit 8. Prohibited circuit 6
is provided between the holding command circuit 10 and the memory circuit 9, and interrupts transmission of the holding command signal h to the memory circuit 9 while receiving the welding signal W from the welding power source 1. Rewriting the contents of the memory circuit 9 is prohibited. Reference numeral 5 denotes a selection circuit that selects welding conditions according to the output of the memory circuit 9. Reference numeral 6 denotes a prohibition circuit provided on the input side of the memory circuit 9, which blocks transmission of the signal to the memory circuit 9 and prohibits rewriting of the contents while the welding signal is being received from the welding power source 1. be. Further, 7 is a push button switch for starting welding, and for example, a torch switch provided on a welding torch is used. In the figure, until the switch 7 is closed, the welding power source 1 has no output, and the output voltage from the auxiliary power source of the counting circuit 8 is applied between the welding torch 2 and the workpiece 3. In this state, when the welding torch 2 and the workpiece 3 are repeatedly short-circuited a predetermined number of times at relatively short intervals, the number of short-circuits is counted by the counting circuit 8 and transmitted to the memory circuit 9. . At this time, since the hold command signal has not yet been input to the E terminal of the memory circuit 9, this value is not loaded. When the welding torch 2 and workpiece 3 are short-circuited a predetermined number of times and are kept open, the hold command circuit 10 detects this relatively long open time and outputs the hold command signal h to the inhibit circuit 6.
Output to. At this time, since the prohibition circuit 6 is not yet in welding, the welding power source 1 outputs the welding signal W.
The hold command signal h is transmitted to the E terminal of the memory circuit 9 as it is. When the storage circuit 9 receives the holding command signal h at the E terminal, it takes in the count value of the counting circuit 8 at that time. On the other hand, holding command circuit 1
0, when a long open time is detected, outputs a holding command signal h and then outputs a return signal c to the counting circuit 8, thereby returning the counting circuit 8 to its initial state. The selection circuit 5 receives the contents stored in the memory circuit 9, selects welding conditions corresponding to the input signal, and supplies the selected welding conditions to the welding power source. In this way, when the switch 7 is closed after selecting the welding conditions, the welding power source 1 is switched to the selection circuit 5.
An output corresponding to the welding conditions selected by is output between terminals a and b, and welding is started. By starting this welding, a welding signal W is output from the d terminal of the welding power source 1, and a cutoff operation is performed to prevent the signal from being transmitted to the prohibition circuit 6.
Prohibits signal capture and storage. As a result, after the start of welding, the welding torch 2 and the workpiece 3
Even if a short circuit occurs, the welding conditions will not change. In the case of the same figure, when the counting circuit 8 is used to count only short circuits lasting a certain period of time, the welding signal from the welding power source 1 is transmitted not when the switch 7 is closed, but when the welding current is being detected. The welding signal may be output only during welding. Further, it is also possible to use a contact type circuit such as a ratchet relay for the counting circuit 8, or to use a digital counter. FIG. 2 is a connection diagram showing a specific embodiment of the main parts of the block diagram in FIG. The circuit and waveform shaping circuit are common. The holding command circuit 10 is configured to receive a branched signal from the middle of the counting circuit 8. The counting circuit 8 includes a diode DR1 for preventing the output from the auxiliary power source E1 and the welding power source 1 from mixing;
It consists of a waveform shaping circuit consisting of a relatively short delay circuit consisting of resistors R81, R82 and a capacitor C81 and a Schmitt trigger circuit 81, and a counter 82, and closes the circuit between the welding torch 2 and the workpiece 3. is counted after noise caused by input signal chatter is removed by a waveform shaping circuit. The memory circuit 9 captures the output of the counter 82 when receiving a pulse at the E terminal, and at the falling edge of the input pulse at the E terminal, stores the input pulse and converts the output of the latch circuit 91 into a decimal number. It consists of a decoder 92 for decoding. As the memory circuit 9, a combination of a binary IC circuit and a decoder, which are commercially available as elements with a latch function, can be used, but if the number of welding conditions is small, a rotary type latch relay or a keep relay can be used in addition to the counter 82. It may also be a contact type using. The holding command circuit 10 includes a DC power supply E3, a transistor TR10, and a resistor R1.
01 to R104, capacitor C101, comparator 101, monostable multivibrator 102 and 1
It consists of 03. The holding command circuit 10 is
The output of the Schmitt trigger circuit 81 in the middle of the counting circuit 8 is received from the transistor TR10, and the capacitor C101 is charged through the resistor R101. This charging voltage is applied to the Schmitt trigger circuit 81.
When the output disappears, it is discharged through resistor R102. The terminal voltage of capacitor C101 is compared by comparator 101 with a voltage obtained by dividing DC power supply E3 by resistors R103 and R104. Here, when the resistance values of the resistors R101 to R104 are respectively expressed as r101 to r104,
If each resistance value is selected so that r102/r101+r102>r104/r103+r104, the positive output of Schmitt trigger circuit 81 charges the terminal voltage of capacitor C101 to a value higher than the terminal voltage of resistor R104. When the voltage at the terminals of capacitor C101 exceeds the voltage at the terminals of resistor R104, comparator 101 produces a positive output. Next, after the terminals a and b are opened and the output of the Schmitt trigger circuit 81 disappears, the capacitor C10
The terminal voltage of capacitor C101 drops and is reversed when the terminal voltage of capacitor C101 becomes lower than the terminal voltage of resistor R104. When the output of the comparator 101 falls, the monostable multivibrator 102 generates a pulse with a predetermined width and supplies it to the monostable multivibrator 103 and also to the inhibition circuit 6 . The monostable multivibrator 103 generates a pulse of a predetermined width in response to the falling edge of the input signal, outputs a reset signal c to the counter 82, and causes the counter 82 to return to its original state. The selection circuit 5 includes transistors TR5-1 to TR5-n that conduct according to the output of the memory circuit 9, relays CR1 to CRn connected in series to each transistor, base resistors R5-1 to R5-n, and a DC power source E2. including. Each welding condition can be determined by relaying, for example, as shown in Figure 3.
A known welding condition setting circuit consisting of n variable resistors VR5-1 to VR5-n and backflow blocking diodes DR5-1 to DR5-n selected by contacts CR1 to CRn can be used.
The number of welding condition setting circuits required corresponds to the types of required welding conditions. The prohibition circuit 6 is an AND gate, and receives the welding signal W from the welding power source 1.
It closes when the welding signal W disappears and opens when the welding signal W disappears. Therefore, in the case of the figure, welding power source 1
The welding signal W is a signal that is low level during welding and high level during welding pauses. FIG. 4 is an explanatory diagram for explaining the operation when selecting welding conditions in the embodiment shown in FIG. 2. In the figure, a shows the voltage change between terminals a and b of the welding power source 1, b is the terminal voltage of the capacitor C81 in FIG. 2, c is the output voltage of the Schmitt trigger circuit 81, d is the terminal voltage of the capacitor C101, f and g indicate the outputs of monostable multivibrators 102 and 103, respectively. In FIG. 4, the welding torch 2 contacts the workpiece twice, from time t1 to t2 and from time t3 to t4.
An example is shown when terminals a and b of the welding power source 1 are closed. Before time t1, capacitor C8
1 is being charged by the power source E1. When terminals a and b are closed at time t1, capacitor C81
starts discharging at a speed determined by resistor R82, but even if the voltage between a and b suddenly changes due to chattering etc., it will not react until it reaches the critical voltage e01 of Schmitt circuit 81. . If the closed circuit continues for a certain period of time, capacitor C8
1 drops below the critical voltage e01, and the Schmitt trigger circuit 81 outputs a signal. next,
When terminals a and b are opened at time t2, capacitor C81 is charged again. At this time as well, the Schmitt trigger 8 does not respond to a short-term open circuit within the time determined by the capacitor C1, resistors R81 and R82, and the critical voltage e02 of the Schmitt trigger circuit 81, but only responds to a longer open circuit.
1 responds. At times t3 and t4, the shot trigger circuit 81 responds in the same way. In this way, the input signal that is likely to be mixed with noise is waveform-shaped and supplied to the counter 82, and is also supplied to the transistor TR10, which is made conductive to charge the capacitor C101. When terminals a and b are opened for a certain period of time or more and the output of the Schmitt trigger circuit 81 disappears, the transistor
TR10 is cut off and capacitor C101 begins discharging through resistor R102. The discharge time constant at this time is made sufficiently longer than the time constant of the waveform shaping section. When the open time between terminals a and b is short, such as from time t2 to t3, the terminal voltage of capacitor C101 does not become lower than the terminal voltage of resistor R104, and terminals a and b are connected at the next time t3. When the circuit is closed again, it will be charged again and recovered. At time t4, terminals a and b are opened again, and this state is maintained thereafter. Capacitor C101 continues to discharge, and finally reaches a value lower than the terminal voltage er of resistor R104 at time t5. reach As a result, the output of the comparator 101 is inverted, and the monostable multivibrator outputs a pulse h of a predetermined time width when the output of the comparator 101 falls. This pulse h becomes a hold command signal and is supplied to an inhibition circuit 6 consisting of an AND gate. At this time, since the welding power source 1 is not welding, the output W is at a high level, so the inhibition circuit 6 is open and the holding command signal h is supplied to the E terminal of the latch circuit 91 of the memory circuit 5. The latch circuit 91 takes in the output of the counter 82 when an input signal is supplied to the E terminal, and stores the signal taken in when the E terminal input disappears. In the example of FIG. 4, since there are two substantial closings between terminals a and b, the count content of the counter 82 is "2" at time t4, and the count content of the monostable multivibrator 102 is "2" at time t5. When the hold command signal h is output from the latch circuit 91, the latch circuit 91 takes in this "2" and holds it when the signal h disappears. When the output signal of the monostable multivibrator 102 falls, the monostable multivibrator 103 outputs a pulse c with a fixed time width to return the counter 82 to zero, but at this time, the latch circuit 91 has already been turned off. Since no signal is supplied to the E terminal, the content of the latch circuit 91 remains at "2". The contents of this latch circuit 91 are as follows:
2 and supplied to the selection circuit 5,
A predetermined relay is energized and welding conditions are selected. After this, when terminals a and b are closed again,
The shutter trigger circuit 81 outputs a signal, and the counter 82 counts the number of times the circuit is closed again. This count value is taken into the latch circuit 91 and stored when the terminals a and b are opened for a relatively long time and the hold command signal h is supplied from the hold command circuit 10. When welding starts, a low-level welding signal is supplied from the d terminal of the welding power source 1 to the prohibition circuit 6 to close it, so even if terminals a and b are opened and closed thereafter, the contents of the memory circuit 9 will change. Not done. In the above embodiment, the prohibition circuit 6 was provided between the hold command circuit 10 and the memory circuit 9 to transmit and cut off the hold command signal h. Alternatively, it may be placed on the input side of the counting circuit 8 or between the counting circuit 8 and the memory circuit 9, for example.

【Effect of the invention】

As described above, in the present invention, the number of times the output terminal of the welding power source is short-circuited during a welding pause is counted, and the welding conditions are selected according to the number of short-circuits, so the welding conditions can be changed remotely. There is no need to prepare a dedicated multi-core cable for selection, there are no disconnection accidents, and the workability is excellent.Furthermore, welding start commands and welding condition switching commands are issued from independent control paths. The selection of welding conditions can be recognized in terms of the digital "number of short circuits" and the welding operator can perform repeated short circuit and open operations according to his/her will, thereby eliminating erroneous operations and malfunctions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the welding machine control device of the present invention, and FIG. 2 is a connection diagram showing a specific embodiment.
3 is a schematic diagram showing an example of the welding condition setting circuit selected by the selection circuit 5 of the embodiment shown in FIG. 2, and FIG. 4 is a diagram showing voltage changes at various parts to explain the operation of the embodiment shown in FIG. 2. FIG. 1... Welding power source, 5... Selection circuit, 6... Prohibition circuit,
8... Counting circuit, 9... Memory circuit, 10... Holding command circuit, 102, 103... Monostable multivibrator.

Claims (1)

[Scope of Claims] 1. In a welding control device that connects a workpiece to be welded and a welding torch to an output terminal of a welding power source and presses a welding start push button switch to start welding, and an auxiliary power source that outputs a low-voltage, small-current direct current that does not generate an arc even when short-circuiting and opening between the output terminals and the welded object, and a welding operation that short-circuits and opens the output terminals for an arbitrary period of time. a counting circuit that counts the number of short circuits when a person repeats the short circuit a predetermined number of times; and when a short circuit is not counted for a predetermined period of time or more, the counting number of the counting circuit is memorized, and the counting number of the counting circuit is reset. a holding command circuit that outputs a holding command signal; a storage circuit that stores count values based on the holding command signal; and a selection circuit that selects welding conditions based on the output signal of the storage circuit; A welding machine control device equipped with a prohibition circuit that prohibits changes in welding conditions.