JPS60148673A - Control device for automatic arc welding - Google Patents

Abstract

PURPOSE:To provide a titled device which accomplishes automatic welding without mutual interference by feeding an electric power source via filters to a servocontrol part, microprocessor and welding power source system and connecting an output control part for current and voltage detection signals, and a microprocessor by means of photocouplers. CONSTITUTION:A primary electric power source 22 is fed via filters 29, 30, 39 to a servocontrol part 37 for positioning, a control microprocessor 26 and a welding power source system 21 to eliminate the fluctuation and interference of a working power source. An output control part 55 for current and voltage detection 63, 64 signals and the microprocessor 26 are connected via DC photocouplers 66, 67 to eliminate the mutual interference of an electrical fluctuation. The respective control parts 26, 37, 55 are thus operated normally without interference by which automatic arc welding is improved.

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 that controls the welding position, and a welding device that supplies electric power and filler wire 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 MX in the X-axis direction. and Y-axis positioning motor My
This is done by driving the microprocessor 3 in accordance with instructions from the microprocessor 3, which has set conditions such as positioning. 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 1 is composed of a welding power source 5 provided separately from the positioning device 4, a wire supply device 6 attached thereto, etc. Interconnection with 4 is planned.

Furthermore, the primary power source for the positioning device 4 and the welding device 9 is provided by a circuit breaker 10 that separately opens and closes the power source as shown in FIG.
and 11 are provided, and are supplied from completely independent power supplies 12 and 13.

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 welding 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 arc welding robot main body and the workbench 2, which is a mounting platform for the workpiece to be welded, there is also a control panel 14 of the positioning device 4 (FIG. 1).
A power source 15 for the welding device 9 (FIG. 1) and an interface unit 16 for interconnecting these devices were provided separately. Furthermore, in the arc welding robot, a gas cylinder 17 used to shield the welding part and a wire pack 18 to store filler wire were also required, so wiring and piping for mutual welding were required. The process becomes quite complicated, which can lead to 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. an electric control system for a torch positioning device;
In an automatic arc welding control device in which a welding power source system that supplies power to the welding torch is incorporated in one control panel, a servo control section of a drive source that drives each axis of the welding torch positioning device, and the welding power source a microprocessor for controlling the output control section of the welding power source system; a coupler section for signal connection between the microprocessor and the output control section of the welding power source system; - the microprocessor and the welding power source system;
An automatic device comprising: a coupler unit for signal connection with the output amount detection unit; and filters provided on the primary sides of the electrical control system of the welding torch positioning device and the welding power supply system, respectively. The present invention provides an arc welding control device.

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). Welding power supply system 2 that supplies power to the system 20 and the welding torch 8
1.

First, the electrical control system 20 of the positioning device will be explained. The electric control system 20 of the positioning device is connected to the electric control system 20 of the positioning device via a circuit breaker 23 that controls the entire power of the control panel 19 from a common power source 22.
Electric power is supplied to the servo motors M8., which position each axis. It is divided into a servo system power supply 24 that drives My, M2 and the wire feeding motor Mw, 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 that includes a signal processing circuit that processes signals and an amplifier that amplifies the signals, and drives the motors MX, My, M2, and Mw of the main body of the welding torch positioning device to perform welding. The torch 8 is positioned and the welding wire is fed. Also, the above motor MX, +1/b, M
.

Signals from tachometers TGX, TG, TG2, and TGW, which are directly connected to the rotating shafts of the motors MX, MW, and MW, and which detect the rotational speeds of the motors, are fed back to the control unit 37, and are also connected to the motors MX, My, and M.

Rotary encoders PEx, PEy, and PR are directly connected to the rotating shaft of the motor and detect the rotational position of the motor.

After the signal is also returned to the control unit 37 and subjected to necessary processing,
The data is sent to the 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 the circuit breaker 38 that protects the power supply and the filter 39 that removes noise, and then passes through the forward conversion circuit 40 that converts alternating current to direct current. is converted into direct current. The filter 39 and a part of the forward conversion circuit 40 are shown in FIG. 6. As shown in the figure, the filter 39, like the filters 29 and 30 described above, prevents the intrusion of harmonic components and pulse noise. The forward conversion circuit 4o is constructed with a three-phase full-wave rectifier circuit using 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.

Since the operation of the inverter is well known, a detailed explanation will be omitted, but the transistors 46, 47 and 48 .
49 is alternately turned on and off, the current flowing to the primary side 51 of the welding transformer 5o is alternated, and high frequency power is induced to the secondary side 52 of the welding transformer 5o. In the figure, a capacitor 53 is a capacitor for supplying reactive power, and a diode 54 is a freewheeling diode that returns reactive power to the power source.

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

The reason why the inverter circuit 45 is used to generate high-frequency alternating current is that the commercial frequency power source is directly connected to the welding transformer 5.
This is because, with the same human power, the weight of the welding transformer 50 is significantly reduced compared to the case where the welding transformer 50 is added to 0, and the entire control panel can be made smaller. 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 an axle 59 provided for improving weldability.

The output of this forward conversion circuit 56 becomes the final output of the welding power supply system 21, and is connected to the welding torch 8 and the base material, which is the workpiece, via a shunt 62 for measuring welding current and terminals 60 and 61. .

On the other hand, the welding current detected by the shunt 62 and the terminal 6
The welding voltage measured between 0 and 61 refers to the welding voltage measured between
It is fed back to the output control section 55. This is because the welding power supply system used in the above embodiment employs 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 state of the switching element No. 5. Note that 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.
This is to protect numbers 6 to 49.

Further, the outputs of the current detection section 63 and voltage detection section 64 described above are sent to the A/D converter 6 which converts the analog signal into a digital signal.
5 and a photocoupler section 66 that has a light emitting section and a light receiving section and transmits signals in an insulated state.
It is reported that.

On the other hand, the command signal of the microprocessor 26 is also connected to the photocoupler section 67, which converts the digital signal into an analog signal.
The signal is sent to the output control section 55 via the A converter 68. This is because the welding conditions change depending on the welding position, so it is necessary to change the welding conditions according to the welding position of welding 1 to 8 and to monitor whether welding is being performed under the predetermined welding conditions. Because there is.

By the way, FIG. 8 shows a specific circuit diagram of the photocoupler section 67 and the D/A converter 68 connected thereto used in the above embodiments. Microprocessor 2 as shown in the figure
6 control signals. -D3 is the photocoupler light emitting part 69~
72 is directly driven to transmit a signal to the light receiving sections 73 to 76, and then the signal is sent to the input of the D/A converter 68 to create an analog signal for setting welding conditions.

In the above embodiment, the signal is transmitted through the photocoupler section 67 at the digital signal stage, but as shown in FIG. After that, it is also possible to transmit using a photocoupler 77 with good linearity.

When transmitting a signal through a photocoupler as described above,
Since the control system of the microprocessor 26 and the control system of the welding power source are electrically independent, they do not interfere with each other.
Furthermore, intrusion of electrical noise is prevented.

In the conventional automatic arc welding control device, welding conditions are set using relay contacts 78 to 80 as shown in Fig. 9.
It was done through. However, using relay contacts 78 to 80 had drawbacks such as long operating time, chattering, and longevity, and the need for a separate interface unit.However, as in this embodiment, a photocoupler is used for signal transmission. By adopting parts 66 and 67, this problem was also solved.

Next, welding wire feeding to the welding torch 8 and gas 2 control will be explained in more detail. As mentioned above, the welding wire is fed while the wire feeding motor Mw, which is rotationally driven by a drive signal from the control unit 37 based on the control position of the microprocessor 26, pinches the welding wire pulled out from the wire pack 18. This is done by driving a feed roller.

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. This is because 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 solenoid valve SQL is controlled by a control signal from the microprocessor 26.
is controlled, and during welding, shielding gas is flowed from the gas cylinder 17 to block the atmosphere and create an appropriate welding 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.

By the way, in the above embodiment, the microprocessor 26
Then, the welding torch 8 was positioned, the welding voltage and current were set, and the shielding gas was controlled.

However, as shown in FIG.
It is also possible to provide a controller 3 and control the welding voltage, welding current, wire feeding, shielding gas, etc. while communicating with the microprocessor 26.

This reduces the burden on the positioning microprocessor 26, and enables the positioning device to perform high-speed follow-up and multi-axis control.

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

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

FIG. 12 shows an automatic arc welding control device 1 according to the above embodiment.
9' is shown, but the control panel 19' has two welding cables 85 and 86 and one control cable 8.
7 is connected, which 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 microprocessor that controls a servo control section of a drive source that drives each axis of the welding torch positioning device, an output control section of the welding power source, the microprocessor, and an output control section of the welding power source system. a coupler unit that connects signals with the output amount detection unit of the welding power source system, a coupler unit that connects signals with the output amount detection unit of the welding power source system, an electric control system for positioning the welding torch, and the welding power source system. This is an automatic arc welding control device characterized by having a component including a filter provided on the primary side.

Therefore, the present invention includes a microprocessor that controls the servo and control section of the welding torch and the output control section of the welding power source, so there is no need to provide a separate control device for the interface, and the welding power source Since the system and the microprocessor are connected via a coupler, there is no mutual interference and unnecessary noise is blocked, and the electrical control system of the welding torch positioning device and the welding power supply system are Since a filter is provided on each primary side, the electrical control system of the welding torch positioning device no longer malfunctions mainly due to noise 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-mentioned arc welding robot according to the conventional example, Fig. 2 is a power supply system connection diagram, and Fig. 3
The figure is an external connection diagram of an automatic welding control device 6 according to a 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.
5 to 8 are detailed circuit diagrams of individual blocks in FIG. 4, FIG. 9 is a welding condition setting circuit diagram according to a conventional example, and FIG. 10 is a welding condition adopted in another embodiment of the present invention. FIG. 11 is a schematic block diagram of a welding power source system adopted in an 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) 19...Control panel 20...Electric control system of positioning device 21...Welding power supply system 26...Microprocessor 29.30...Filter 37...Control unit 39...
- Filter 66... Photocoupler section 67... Photocoupler section.

Claims (2)

[Claims] (1) In an automatic arc welding control device 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, the following: An automatic arc welding control device comprising the components (a) to (d). (a) A microprocessor that controls a servo control section of a drive source that drives each axis of the welding torch positioning device and an output control section of the welding power source. (b) A coupler unit that connects the signal between the microprocessor and the output control unit of the welding power source system. (C) A coupler unit that connects signals between the microprocessor and the output amount detection unit of the welding power supply system. (d) Each primary side of the electrical control system of the welding torch positioning device and the welding power supply system. filters installed in each. (2) The automatic arc welding control device according to claim 1, wherein the welding power supply system has an inverter circuit made of switching elements.