JPS6163369A - Separation type arc welding machine - Google Patents

Abstract

PURPOSE:To obtain a titled welding machine for minimizing the number of connecting cables by separating an arc welding machine into a welding power source and a wire feeding device, and connecting them by a welding power cable, a controlling power supply cable, and a voltage converting output current signal cable. CONSTITUTION:An arc welding machine is separated into a welding power source 1 and a wire feeding device 2 having a welding torch 6. They are connected by cables 5a, 5b for feeding a welding power to the torch 6 from a main circuit 101. Also, a controlling power source 108 for stopping an emission of a shield 9 and stopping 206 a feed of a wire 203 by a sequence control part 207 operated by a welding start trigger switch containing the torch 6 is sent by a supply cable 4 for control. also, an output voltage of the sequence control part 207 is sent to an input impedance switching circuit 107 by a cable 3 as an analog current by a converting circuit 209, and sent as a voltage to an output voltage controller 104 by a converting circuit 102. As for the respective circuits, the power cable 5a is used in common, therefore, the number of connecting cables is minimized, and the welding machine can be handled easily.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a separate type arc welding machine that is separated into two or more parts and connected to each other by a cable.

[Conventional technology]

Some arc welding machines have a welding power source, wire feed control, output adjustment, etc. all integrated, but it will be easier to work if these are separated. When the above-mentioned parts are installed separately, it is necessary to connect them with cables to transmit and receive control signals. For example, in a consumable electrode type arc welding machine using a constant voltage power source, this control signal includes an output voltage setting signal and a welding start signal from the output adjustment section to the welding power source section.

Conversely, it is necessary to transmit a welding current detection signal from the welding power supply section to the output adjustment section in order to self-hold the welding start signal as the stop signal.

In addition, the wire feed speed setting value, that is, the welding current setting signal and the shielding gas discharge command signal, are required between the output adjustment section and the wire feed control section, and these are transmitted through dedicated control cables. This requires a large number of cable cores, and the longer the distance between each device, the more cables are required and the equipment becomes more expensive. This increases the number of opportunities and requires a great deal of effort and expense for maintenance.

To solve this problem, a welding power cable is also used as a control cable, and in order to separate the welding current and control signal, the control signal is converted into a frequency signal by a voltage/frequency conversion circuit, and this frequency signal is used as the welding power cable. A method has been considered in which the signal is sent to the receiving side via a cable, and the receiving side performs inverse conversion to return it to a voltage signal. (For example, JP-A-58-47
No. 569) [Interval point 1 to be solved by the invention However, although the above-mentioned prior art can reduce the number of cables, it has the following disadvantages. That is, in arc welding, the welding current changes randomly at extremely high speed, and the current and voltage waveforms contain many high frequency components. Moreover, since this high frequency component is based on fluctuations in the welding power itself, it has a high energy that is incomparable to the control signal, so it is impossible to completely separate the control signal and welding power during welding. Therefore, malfunctions were extremely likely to occur.

In addition, even in the above method, the signal is one-way, and if it is necessary to send and receive signals in both directions at the same time, it is necessary to prepare separate cables for each, so it is not very effective in reducing the number of cables. The present invention solves the above-mentioned drawbacks of the prior art, and is completely unaffected by the welding current not only when welding is stopped but also during welding.
Moreover, the present invention proposed an arc welding machine that can simultaneously transmit and receive signals from both ends connected to the same cable.

[Means for Solving the Problems] The present invention provides an output voltage detection circuit that detects the output voltage of the output path and generates a digital signal in one separately installed part, and an output voltage detection circuit that detects the output voltage of the output path and generates a digital signal. A current/voltage conversion circuit and a switching circuit that changes the impedance of the hexagonal circuit in stages according to the digital signal to be transmitted are provided, and a pair of control cables are connected between these two parts to convert the analog signal and digital signal. It is possible to send and receive both at the same time. Furthermore, the number of cables is further reduced by sharing one wire of the electric cable as one of the cables for the signal transmission.

[Effect]

As described above, the present invention first converts the control voltage signal, which is an analog signal, into a constant current signal corresponding to the signal voltage on the transmitting side, and then transmits it, and then converts this current signal inversely into a voltage signal on the receiving side. In addition to obtaining the control voltage signal, the digital signal is sent to the transmitting side by switching the impedance of the heka circuit in stages according to the digital signal to be transmitted on the receiving side of the analog signal. This makes it possible to transmit and receive data simultaneously using a common cable.

〔Example〕

FIG. 1 is a connection diagram showing an embodiment of the present invention.

In the figure, 1 is a welding power source, and there is a main circuit section 101 inside which converts three-phase AC input into DC with characteristics suitable for welding.
, a current/voltage conversion circuit 102 that converts an input signal current into a voltage signal, an input signal detection circuit 103 that generates a signal based on the input signal, an output voltage control circuit 104 . a current transformer 105 for detecting a welding current; a welding current detection circuit 1 that receives the output of the current transformer 105 and drives a relay WCR;
06, includes an input impedance switching circuit 107 consisting of a parallel circuit of an output contact WCRb of the welding current detection circuit 106 and a resistor RZ, and a control power supply circuit 108. 2
is a wire feeding device for feeding a consumable electrode wire (hereinafter simply referred to as a wire) to a welding part, and is driven by a wire feeding electric motor 201 and an electric motor 1201 inside to feed a wire 203 from a wire reel 202. A motor control circuit 206 for controlling the rotational speed of the electric motor 201 to a speed according to the setting value of the welding current setting device 205, and a motor control circuit 206 for controlling shield gas discharge, stopping, welding start, stopping, etc. sequence controller 207, and an output voltage setter 208 that outputs a reference voltage signal for setting the welding voltage. Voltage/current conversion circuit 2 that converts the output voltage of the output voltage setter 208 into a corresponding constant current signal
09. It includes an output voltage detection circuit 210 that detects the output voltage of the voltage/current conversion circuit 209 and generates a digital signal corresponding to a stepwise change in the input voltage, and a shield gas discharge electromagnetic valve 211. 3 is a single-core cable for transmitting the output current signal of the voltage/current conversion circuit 209 to the welding power source 1. Reference numeral 4 denotes a single-core cable that supplies power for control to the wire feeding device 2, and each return wire of the cable 3 and the cable 4 shares one of the welding power cables 5λ and 5b, 5a. Reference numeral 6 denotes a welding torch, which has a built-in switch for commanding the start of welding.

7 is the welding point and is usually at ground potential. Also, the output voltage is A+1! The welding power cable 5a is connected to each ground wire of the control circuit of the welding power source 1 and the control circuit of the wire feeding device 2, respectively, in order to share the return wires of the control signal and control power with one of the welding power cables 5a. Connecting. 8 again
is a shielding gas supply source, which is connected to the welding torch 6 via the welding power source 1 and the wire feeding device 2 through a gas hose 9.

In the embodiment shown, a welding torch 6 is used to start welding.
When the bird closes the switch, this switch closing signal S
is sent to the sequence control unit 207, which first opens the shield gas discharge electromagnetic valve 211 and releases the shield gas to the welding torch 6.
released from. After the shielding gas starts to be discharged, the motor control circuit 206 starts the motor 201 and starts feeding the wire 203. At the same time as this wire feeding, or a little before this, sequence control unit 2
07 issues an output command, and begins supplying the output type of the 1@ welding power source 1. Sequence control unit 207
In response to a command signal from the output voltage setting device 208, the output voltage Er of the output voltage setting device 208 is converted into a constant current Ir corresponding to the set voltage Er by the voltage/current conversion circuit 209, and the control cable 3 and the welding power cable 5 The current/voltage conversion circuit 10 receives the output of the input impedance switching circuit 107.
At step 2, the current signal 1r is returned to the original voltage signal Er and transmitted to the output voltage control circuit 104. Further, the detection circuit 103 supplies a logic signal "1" to the output voltage control circuit 104 upon receiving the current signal tr. When the output voltage control circuit 104 receives the output voltage control signal Er and the logic signal "1"', it sends an output adjustment signal to the main circuit section 101, and the main circuit section 101 adjusts the welding power to the welding torch 6. The material to be welded is supplied to the workpiece 7, and welding is started. This output voltage control circuit 1
The output of 04 is a firing pulse signal for the thyristor when the main circuit section 101 uses a unidirectional thyristor to phase-control rectify the AC power source, and when the main circuit section 101 is an analog element such as a transistor, it is an ignition pulse signal. This is an analog signal that controls the conduction state of

On the other hand, immediately after the welding torch trigger closes the switch, the wire 203 has not yet reached the workpiece 7.
Furthermore, no welding arc is generated, so no welding current is flowing. For this reason, current transformer 105 does not generate an output, and relay WCR of output current detection circuit 106 remains de-energized. Therefore, the normally closed contact WCRb of the relay WC remains closed, the impedance of the input circuit of the current/voltage conversion circuit 102 is low, and as a result, the output terminal voltage of the voltage/current conversion circuit 209 becomes low. For this purpose, the output voltage detection circuit 210 detects a low voltage and outputs a welding non-starting state to the sequence control unit 207. When the wire contacts the workpiece 7 and welding current begins to flow, current transformer 105 detects this, and relay WCR of welding current detection circuit 106 is energized to open contact WCIJ. This results in voltage/
The impedance of the output circuit of the current conversion circuit 209 becomes high, and in order to maintain a constant current output against this high impedance, the output voltage of the voltage/current conversion circuit 209 becomes ■rR.
It's only 2 minutes higher. In response to this high output voltage, output voltage detection circuit 210 outputs a welding current detection signal to sequence control section 207. Therefore, it is necessary to set the resistor to a value that is sufficiently high compared to the voltage generated in the cable due to changes in the output voltage of the voltage/current conversion circuit 209, welding current flow, or other noise. .

Normally, the sequence control unit 207 has a circuit configuration such that while the welding current is not flowing, the bird directly responds to the opening and closing of the switch to open and close the output of the welding power source 1, and continues to maintain the welding sound by itself. .

Therefore, if the output signal of the output voltage detection circuit 210 at high voltage is supplied to the sequence control section 207 as a welding current detection signal, the welding current detection signal can also be transmitted at the same time by the cable for transmitting the welding voltage setting signal 1. Of course, this signal can also be used as a signal for other command signals, such as a signal for switching the wire feed speed from low speed 1 before welding starts to actual high speed, switching the flow rate and type of shielding gas, or moving the welding torch in a fully automatic welding machine. It can also be used as a start command signal, etc.

Note that as one line of the signal transmission cable connecting each part, a cable for supplying control power to the welding power cable may be used in common. In addition, the input impedance switching circuit provided on the receiving side of the constant current control signal is simply
In addition to using one resistor, two or more resistors may be used to switch the effective input impedance in multiple stages using a plurality of digitized signals.

Also, similar effects can be obtained by replacing these resistors with constant voltage diodes.

Furthermore, as for each part of the welding machine that is provided separately, in addition to the welding power source and the wire feeding device as shown in the example shown in the figure, the welding power source has a wire feeding speed setting device (i.e., a welding current setting device). ), or the output regulator is separated into a separate remote control box, or any other object may be used. Further, when the welding power source used has constant current characteristics, it is sufficient to supply an output current setting signal to the welding power source and a welding voltage setting signal to the wire feeding device.

〔Effect of the invention〕

As described above, in the present invention, since the voltage signal to be transmitted is converted into a corresponding constant current signal and sent, a power cable carrying a large amount of power is connected to one side of the signal transmission cable. By sharing the cables, there will be no negative impact even if the number of cables is reduced, and since the analog signals to be transmitted are made constant current, the output voltage on the transmitting side can be changed by digitally changing the input impedance of the receiving circuit. However, this change can be detected on the transmitting side of the constant current signal and the digital signal from the receiving side can be determined, so it is possible to transmit and receive analog signals and digital signals simultaneously in both directions using a common cable. This allows the number of cables to be minimized.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention. 1... Welding power source, 101... Main circuit section, 102...
- Current/voltage conversion circuit, 103... Input signal detection circuit, 104... Output voltage control circuit, 105... Current transformer. 106... Welding current detection circuit, 107... Switching circuit, 2... Wire feeding device, 208... Output voltage setting device. 209... Voltage/current conversion circuit, 210... Output voltage detection circuit, 3... Cable, 4... Control power supply cable 5a, 5b... Power cable for welding Agent Patent attorney Nakai Hiroshi procedural amendment side (suicide September 28, 1982)

Claims (1)

[Claims] In a separate type arc welding machine that is separated into one or two or more parts and connected to each other by a cable, an output adjustment section that generates an analog voltage signal to one of the mutually connected parts. , a voltage/current conversion circuit that converts the output voltage of the output adjustment section into a constant current signal corresponding to the voltage and outputs the same; and a voltage/current conversion circuit that receives the output voltage of the voltage/current conversion circuit as an input and generates a digital signal corresponding to the input voltage. an output voltage detection circuit for transmitting the effective impedance of a current/voltage conversion circuit for converting a current signal from the one part into a voltage signal and an input circuit for the current signal to the other part corresponding to the one part; a switching means for changing the digital signal in steps according to the digital signal to be output, and a pair of cables connects the two parts, and the analog signal is output from the one part, and the digital signal is output from the other part. Separate type arc welding machine that transmits and receives signals simultaneously using a common cable. 2. The separate type arc welding machine according to claim 1, wherein one of the pair of cables is shared with a welding power cable or a control power supply cable. 3. The separate type arc welding machine according to claim 1, wherein the switching means is means for changing the series resistance value of the input circuit for the current signal in stages. 4. The separate type arc welding machine according to claim 1, wherein the switching means is means for connecting a constant voltage diode in series to the input circuit for the current signal.