JPH0369627B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for controlling a welding torch positioning device such as a robot, which has degrees of freedom in two or more axes, and a welding machine that supplies electric power to the welding torch.

In recent years, arc welding robots that perform arc welding have been widely adopted.This arc welding robot has a positioning device body that controls the welding position, and a welding device that supplies electric power and welding wire, which is a filler metal, to the welding part. The positioning device and the welding machine each have an electrical system control device.

FIG. 1 shows a schematic block diagram of the electrical system of a conventional electric arc welding robot. As is well known, the positioning of the welding torch 8 in the X-axis and Y-axis directions is performed by a positioning motor M in the X-axis direction. _x and Y
This is performed by driving the axial positioning motor M _y in accordance with commands from the microprocessor 3 in which conditions such as positioning are set. However, in the case of a cylinder-driven robot, a hydraulic cylinder controlled by a servo valve is used as the drive source.

On the other hand, the welding device 9 of the arc welding robot is
It consists of a welding power source 5 provided separately from the positioning device 4 and a wire supply device 6 attached thereto, and is interconnected with the positioning device 4 via an interface circuit 7.

Furthermore, the primary power source for the positioning device 4 and welding device 9 is supplied from completely independent power sources 12 and 13 via circuit breakers 10 and 11 that separately open and close the power sources, as shown in FIG. .

This is because the power source 13 of the welding device 9 requires much larger power than the power source 12 required by the positioning device 4, so it requires a large installation space, and the power source 13 has large load fluctuations. This is because the positioning device 4 may malfunction because it becomes a noise source due to thyristor control or the like.

Therefore, conventionally, as shown in FIG. 3, in addition to the main body of the arc welding robot 1 and the workbench 2, which is a mounting platform for the workpiece to be welded, a control panel 14 of the positioning device 4 (FIG. 1) is used. , a power source 15 for the welding device 9 (FIG. 1), and an interface unit 16 that interconnects these are separately provided. Furthermore, the arc welding robot also required a gas cylinder 17 used to shield the welding part and a wipe pack 18 to store the filler wire, so wiring and piping for mutual welding were required. This became quite complicated and was a cause of equipment failure.

The present invention aims to solve the above-mentioned drawbacks and provide an automatic arc welding control device that is compact as a whole and has fewer failures. In an automatic arc welding control device in which an electric control system for a torch positioning device and a welding power source system for supplying power to the welding torch are incorporated into one control panel, power control for the welding torch in the welding power source system is provided. A circuit for performing this is configured with an inverter circuit consisting of a switching element, and a noise removing circuit is provided on each primary side of a power supply system for the electrical control system of the welding torch positioning device and the welding power supply system. a filter; provided on the secondary side of the power supply system of the electrical control system via the filter;
The servo control section of a drive source provided on the secondary side of the power supply system of the electric control system is connected to the servo control section of the drive source provided on the secondary side of the power supply system of the electric control system through the filter to drive each axis of the welding torch positioning device, and the power supply of the welding power supply system is connected through the filter. a microprocessor that performs feedback control of an output control section for the inverter circuit provided on the secondary side of the system; A coupler unit that connects signals to the control unit in an electrically insulated state and a power output amount detection unit for the microprocessor and the welding torch are interposed, and the coupler unit connects signals to the control unit in an electrically insulated state, and The present invention provides an automatic arc welding control device comprising a coupler section that connects signals to a microprocessor in an electrically insulated state.

Among the above components, the coupler section includes a photocoupler, an acoustic coupler, etc. that transmit signals by light, sound, etc., and the output amount of the welding power source system includes both or one of the welding voltage and welding current.

Next, an automatic arc welding control device according to an embodiment of the present invention will be explained with reference to the attached drawings to provide an understanding of the present invention.

FIG. 4 is a block diagram showing the entire control circuit of an automatic arc welding control device according to an embodiment of the present invention, FIGS. 5 to 8 are detailed circuit diagrams of individual blocks in FIG. 4, and FIG. FIG. 10 is a welding condition setting circuit diagram according to a conventional example, FIG. 10 is a welding condition setting circuit diagram adopted in another embodiment of the present invention, and FIG. 11 is a schematic block diagram of a welding power source system adopted in an embodiment of the present invention. , FIG. 12 is an external connection diagram of the automatic arc welding control device according to the above embodiment.

Note that the same reference numerals will be used to describe the same elements as those used in the conventional example shown in FIGS. 1 to 3.

As shown in FIG. 4, the control panel 19 is equipped with an automatic arc welding control device according to an embodiment of the present invention, which electrically controls the positioning device of the welding torch 8 (FIG. 3). The welding power supply system 20 and the welding power supply system 21 supply power to the welding torch 8.

First, the electrical control system 20 of the positioning device will be explained. Power is supplied from a common power supply 22 to the electric control system 20 of the positioning device via a circuit breaker 23 that controls the power of the entire control panel 19, and the power is supplied to the servo motors M _x , which perform positioning of each axis.
It is divided into a servo system power supply 24 that drives M _y , M _z and the wire feeding motor M _w , and a control system power supply 25 that supplies power to control elements such as a microprocessor 26 . The respective power supplies are provided with filters 29 and 30 for removing power supply noise and the like via circuit breakers 27 and 28.

FIG. 5 shows a specific circuit diagram of the filters 29 and 30. The harmonics of the power supply, noise pulses, etc. are blocked by reactors 35 and 36, and capacitors 31 to 34 are used to bypass the power supply to ground. It is configured to remove noise from inside the device, as well as noise generated from within, and prevent it from being transmitted to the outside.

The microprocessor 26 receives power from the control system power supply 25 and receives operation instructions for the welding torch 8 from an input device (not shown). The control unit 37 is connected to a control unit 37 having an amplifying amplifier, and drives the motors M _x , M _y , M _z and M _w of the main body of the welding torch positioning device to position the welding torch 8 and move the welding wire. We are sending supplies. Moreover, the above motors M _x , M _y , M _z and
Signals from tachometers TG _x , TG y , TG z , and TG w that are directly connected to the rotating shaft of M _w and detect the rotational speed of the motors are fed back to the control section 37 , and similarly, the signals of the tachometers TG x , TG _y , TG _z , and TG _w that detect the rotation speed of the motors are fed back to the control unit ₃₇ . The signals of the rotary encoders _{PE x} , PE y , and PE _z that are directly connected to the rotating shafts of the motors PE _x , PE _y , and PE _z and that detect the rotational position of the motors are also transmitted to the control unit 37 .
After being returned to and subjected to necessary processing, it is sent as data to a microprocessor 26 to control the positioning of the welding torch 8.

Next, the welding power supply system 21 will be explained.

The commercial frequency power supplied through the circuit breaker 23 that controls the power of the control panel 19 passes through a circuit breaker 38 that turns the power on and off and a filter 39 that removes noise, and then passes through a forward conversion circuit 40 that exchanges alternating current into direct current. It is replaced with direct current. The filter 39 and a part of the forward exchange circuit 40 are shown in FIG.
Similar to 9 and 30, a reactor 41 that prevents harmonics and pulse noise from entering, and capacitors 42 and 43 that bypass the harmonics and pulse noise.
The forward conversion circuit 40 includes a three-phase full-wave rectifier circuit including a diode 44.

The power converted into DC by the forward conversion circuit 40 is converted into high frequency AC by an inverse conversion circuit 45 which converts DC into AC.

As shown in FIG. 7, the inverse conversion circuit 45 employs a bridge type inverter circuit using transistors 46 to 49 as switching elements.
The operation of the inverter is well known and will not be described in detail, but it is performed by alternately turning on and off the transistors 46 and 47 and the transistors 48 and 49, thereby alternating the current flowing to the primary side 51 of the welding transformer 50. This induces high frequency power to the secondary side 52 of the welding transformer 50. A capacitor 53 in the figure is a capacitor for supplying reactive power,
The diode 54 is a freewheeling diode that sends reactive power back to the power supply side.

Here, signals for controlling the transistors 46 to 49 are sent from an output control section 55, and the welding transformer 50 is controlled by controlling the on/off period and width of the transistors 46 to 49 based on the above signals.
The power supplied to is controlled.

In addition, using an inverter circuit to generate high-frequency alternating current allows the same input, the weight of the welding transformer 50 to be significantly reduced, and the overall size of the control panel to be smaller than if the commercial frequency power source was directly applied to the welding transformer 50. This is because it allows for Further, in the above embodiment, an inverter using a transistor is used as the inverse conversion circuit 45, but it is also possible to use an inverter using a thyristor.

By the way, the high frequency alternating current power transmitted to the secondary side 52 of the welding transformer 50 is converted into direct current by a forward conversion circuit 56. As shown in FIG. 7, the forward conversion circuit 56 includes a single-phase full-wave rectifier circuit including diodes 57 and 58, and a reactor 59 provided to improve weldability.

The output of this forward conversion circuit 56 is the output of the welding power supply system 21
This is the final output of shunt 6 for welding current measurement.
2 and terminals 60 and 61, the welding torch 8 and the base material to be welded are connected.

On the other hand, the welding current detected by the shunt 62 and the welding voltage measured between the terminals 60 and 61 undergo necessary processing in the current detection section 63 and voltage detection section 64, respectively, and then the output control section 55 Feedback will be provided to This is because the welding power supply system used in the above example uses constant voltage control in which the output voltage does not change even if the load fluctuates under certain welding conditions. This is to control the on/off of. The welding current is also fed back to the output control section 55, but this is due to the short circuit current that flows when the load is short-circuited for a long time.
58 and the transistors 46 to 49.

In addition, the current detection section 63 and voltage detection section 64 described above
The output of There is. On the other hand, a command signal from the microprocessor 26 is also sent to the output control section 55 via a photocoupler section 67 and a D/A converter 68 that converts a digital signal into an analog signal. This is because the welding conditions change depending on the welding position, so it is necessary to change the welding conditions in accordance with the welding position of the welding torch 8 and to monitor whether welding is being performed under the predetermined welding conditions. be.

By the way, FIG. 8 shows a specific circuit diagram of the photocoupler section 67 used in the above embodiment and the D/A converter 68 connected thereto. As shown in the figure, the control signals D ₀ to D ₃ of the microprocessor 26 directly drive the light emitting sections 69 to 72 of the photocoupler, transmitting signals to the light receiving sections 73 to 76, and then input the signals to the D/A converter 68. It sends signals to the section and creates analog signals for setting welding conditions.

In the above embodiment, the signal was transmitted by the photocoupler section 67 at the digital signal stage, but
As shown in FIG. 10, the control signal from the microprocessor 26 is immediately converted into an analog signal by a D/A converter 68', and then converted to a photocoupler 77 with good linearity.
It is also possible to transmit by

When signals are transmitted via the photocoupler as described above, the control system of the microprocessor 26 and the control system of the welding power source are electrically independent, so they do not interfere with each other, and furthermore, electrical noise is prevented from entering. Prevented.

In the conventional automatic arc welding control device, welding conditions are set via relay contacts 78 to 80, as shown in FIG. 9. However, when relay contacts 78 to 80 are used, the operation time is long, problems such as chattering and lifespan occur, and there are disadvantages such as the need for a separate interface unit. By adopting 67, this problem was also solved.

Next, welding wire feeding to the welding torch 8 and gas control will be explained in more detail. As mentioned above, the welding wire is fed by the wire feed motor _Mw , which is rotationally driven by a drive signal from the control section 37 based on the control position of the microprocessor 26, which is connected to the wire pack 1.
This is carried out by driving a wire feeding roller which is clamping the welding wire pulled out from 8.

This is determined by the position of the welding torch, the shape of the workpiece, etc., since the welding conditions change depending on the feeding speed of the welding wire. That is, it is necessary to adjust the wire feeding speed to optimal welding conditions.

Also, during welding, it is necessary to flow a shielding gas to isolate the welding area from the outside air, but in the above embodiment, the gas electromagnetic valve SOL is controlled by the adjustment signal from the microprocessor 26, and the gas cylinder 17 is closed during welding. A suitable welding atmosphere is created by flowing more shielding gas to block the atmosphere.

Furthermore, a display unit 82 for welding current, welding voltage, etc. is also connected to the microprocessor 26, and displays the welding current, welding voltage, etc. detected by the current detection unit 63 and voltage detection unit 64, so that it is possible to check the welding conditions even by visual measurement. It has a structure that allows for judgment.

In the above embodiment, the microprocessor 26 positions the welding torch 8, sets the welding voltage and current, controls the shielding gas, etc. However, as shown in FIG. 11, it is also possible to provide another microprocessor 83 and control the welding voltage, welding current, wire feeding, shielding gas, etc. while communicating with the microprocessor 26.

This allows the microprocessor 2 for positioning to
6 can be reduced, and high-speed followability and multi-axis control of the positioning device can be achieved.

Here, the microprocessor 83 has a display section 84.
It is also possible to display the welding current and welding voltage.

This makes it possible to display key operations that are input terminals (not shown).

FIG. 12 shows the state of the external wiring of the automatic arc welding control device according to the above embodiment. Two welding cables 85 and 86 and one control cable 87 are connected to the control panel 19. It is simpler than the conventional automatic arc welding control device shown in FIG.

As described above, the present invention provides automatic arc welding in which an electric control system for a welding torch positioning device having degrees of freedom in two or more axes and a welding power supply system for supplying power to the welding torch are incorporated into one control panel. In the control device, a circuit for controlling power to the welding torch in the welding power source system includes an inverter circuit including a switching element, and a power source for the electric control system of the welding torch positioning device and the welding power source system. A filter for noise removal provided on each primary side of the system, and a filter provided on the secondary side of the power supply system of the electrical control system via the filter, and for driving each axis of the welding torch positioning device. The servo control unit of the drive source is provided on the secondary side of the power supply system of the power supply control system via the filter, and the inverter circuit is provided on the secondary side of the power supply system of the welding power supply system via the filter. a microprocessor that performs feedback control of an output control section for the output control section; A coupler part that performs in the state,
a coupler section that is interposed between the microprocessor and the output amount detection section for power to the welding torch, and connects the signal from the output amount detection section to the microprocessor in an electrically insulated state; An automatic arc welding control device comprising:

Therefore, since the present invention includes a microprocessor that controls the servo control section of the welding torch and the output control section of the welding power source, there is no need to provide a separate control device for the interface, and the welding Since the power supply system and the above-mentioned microprocessor are connected via a coupler, there is no mutual interference and unnecessary noise is blocked. Furthermore, the electrical control system of the above-mentioned welding torch positioning device and the above-mentioned welding power supply system are connected. Since a filter is provided on each primary side of the welding torch, the electrical control system of the welding torch positioning device no longer malfunctions due to noise mainly generated from the welding power supply system.

This makes it possible to incorporate the electric control system of the welding torch positioning device and the welding power source that supplies power to the welding torch into one control panel. The arrangement with the automatic arc welding control device has been significantly simplified, and failures have been reduced.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of the electric system of the above arc welding robot according to the conventional example, Fig. 2 is a connection diagram of the same power supply system, Fig. 3 is an external connection diagram of the automatic welding control device according to the conventional example, and Fig. 4 is a block diagram showing the entire control circuit of an automatic arc welding control device according to an embodiment of the present invention, FIGS. 5 to 8 are detailed circuit diagrams of individual blocks in FIG. 4, and FIG. 9 is a diagram showing a conventional example. Such a welding condition setting circuit diagram, FIG. 10, is a welding condition setting circuit diagram adopted in another embodiment of the present invention, FIG.
The figure is a schematic block diagram of a welding power source system adopted in one embodiment of the present invention, and FIG. 12 is an external connection diagram of the automatic arc welding control device according to the above embodiment. (Explanation of symbols), 8... Welding torch, 19...
Control panel, 20...Electrical control system of positioning device, 2
1...Welding power supply system, 26...Microprocessor, 29, 30...Filter, 37...Control unit,
39... Filter, 40... Forward conversion circuit, 45...
... Inverse conversion circuit, 55 ... Output control section, 63 ... Current detection section, 64 ... Voltage detection section, 66 ... Photocoupler section, 67 ... Photocoupler section.

Claims (1)

[Claims] 1. Automatic arc welding control in which an electric control system for a welding torch positioning device having degrees of freedom in two or more axes and a welding power supply system for supplying electric power to the welding torch are incorporated into one control panel. In the apparatus, a circuit for controlling power to the welding torch in the welding power supply system is configured with an inverter circuit consisting of a switching element, and the following components (a) to (d) are included. An automatic arc welding control device featuring: (a) A filter for noise removal provided on each primary side of a power supply system for the electric control system of the welding torch positioning device and the welding power supply system. (b) installed on the secondary side of the power supply system of the electric control system through the filter, and installed on the secondary side of the power supply system of the electric control system through the filter to drive each axis of the welding torch positioning device; A microprocessor that performs feedback control of a servo control section of a drive source provided on the side and an output control section for the inverter circuit provided on the secondary side of the power supply system of the welding power source system via the filter. (c) A coupler section that is interposed between the microprocessor and the output control section and connects signals from the microprocessor to the output control section in an electrically insulated state. (d) Interposed between the microprocessor and the output amount detection section of the electric power to the welding torch, and connects the signal from the output amount detection section to the microprocessor in an electrically insulated state. coupler part.