JPS583788A - Position setter for tungsten electrode - Google Patents

Abstract

PURPOSE:To maintain the spacing between an electrode and the groove surfaces of base materials most adequately without laborious work in an automatic TIG welding device by locating the electrode at the optimum spacing from the base materials and starting welding upon detection of the contact between the electrode and the base metals at the start of welding with electric current. CONSTITUTION:A setter 21 for positioning of electrode is applied with +15V by a welding start switch and outputs a positive set voltage to a servocontrol amplifier 20, then a servocontrol motor 10 runs in a forward direction. A W electrode 2 is moved downward at a low speed by means of pinion 9, a rack 8, etc. until its leading end contacts with base materials 3. At this time, B contacts 14a are closed, and electric current flows from an electric power source 16 to a relay 15 through a diode 17, the materials 3, the electrode 2, a coil 12, and the contacts 14, then the relay 15 turns on. The motor 10 is thus stopped and -15V is applied to the setter 21, by which the electrode 2 is moved upward. It is stopped by a timer after a constant time. At the same time, a welding start command signal is inputted to the power source 1 and the welding is started.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tungsten electrode positioning device at the start of welding in a TIG automatic welding device.

Conventionally, when starting TIG welding, a method is used in which a high frequency voltage of, for example, 2 MHz, 5000 V is applied between a tungsten electrode and a welding base material to generate spark discharge, and then arc discharge is started. On the other hand, during welding, the distance between the tungsten electrode and the welding base material is 1 to 4 cm, and the voltage is approximately 9 to 14 V, and this arc voltage is detected to adjust the distance between the electrode and the base material. .

Generally, in TIG welding, it is known that the distance between the tip of the tungsten electrode and the groove surface of the base material greatly influences the initiation of arc discharge. That is, if the distance between the tungsten electrode and the base metal is too narrow, the electrode and base metal may short-circuit at the same time as discharge starts, or spatter may adhere to the tip of the electrode, making it impossible to perform good welding. On the other hand, if the distance between the electrode and the base material is too wide, spark discharge will occur.

However, even if an arc occurs, the voltage is too high and the arc voltage control device operates rapidly.
There were problems such as a situation where the electrode was forced into the molten pool due to inertia.

Furthermore, in the past, especially when welding large structures using TIG automatic welding equipment, the distance between the electrode attached to the welding equipment and the base metal groove surface was automatically adjusted to the relationships 1 to 4 above. Difficult to set up.

This required the complicated work of manually adjusting it visually.

The present invention was made in view of the above circumstances, and its purpose is to start TIG automatic welding.

The tungsten electrode itself is used to control the distance between the tungsten electrode and the base metal groove to the optimum value without requiring any special sensors, and welding is started after the tungsten electrode positioning is completed. Therefore, it is an object of the present invention to provide a tungsten electrode positioning device for a TIG automatic welding device that can eliminate the above-mentioned problems.

Hereinafter, two embodiments of the tungsten electrode positioning device according to the present invention will be described based on the drawings.

As shown in FIGS. 1 and 2, a tungsten electrode 2 is connected to a negative output terminal 1a of a welding power source 1.

Ru. Note that a current transformer 4 is provided in the cable between the welding power source l and the base material 8, and this current transformer 4 is connected to a current detector 5.
Ru. Further, a relay 6 is connected to the current detector 5. One end of a support rod 7 that supports the tungsten electrode 2 is fixed to the tungsten electrode 2, and a rack 8 is attached to the other end of the support rod 7.
is fixed.

In addition, a pinion 9 is engaged with this rack 8, and
A rotating shaft 11 of a servo motor 10 is fixed to this pinion 9 coaxially with the pinion 9. A pinion 9 is rotationally driven by a servo motor 1o, and as the pinion 9 rotates, the rack 8 moves up and down while being guided by a guide member (not shown), and the tungsten electrode 2 moves up and down as the rack 8 moves up and down.

On the other hand, a coil 1 is placed between the tungsten electrode 2 and the base material 8.
2 and a capacitor 13 are connected, and furthermore, in parallel with the capacitor 13 of this filter circuit, the B contact 14a of the relay 14 and the relay 15 are connected to the power supply 16 connected to the relay 15 on the negative side, and the cathode is connected to the power supply. A series circuit with a diode 17 connected to the positive side of 16 is connected. The connection point between the capacitor 13 and the base material 8 is grounded, and the connection point between the capacitor 13 and the coil 12 is connected to A of the relay 14.
It is connected to the comparator 18 via contact 14b.

An arc voltage setting device 19 is connected to the comparator 18, and further, the comparator 18 is connected to a servo amplifier 20 via the A contact 14C of the relay 14, and the servo amplifier 20 is connected to the servo motor IO.・In addition, the B contact 14d of the relay 14 is connected to the connection point between the A contact 14C and the servo amplifier 20.
The output terminal 21a of the electrode positioning setting device 21 is connected through the terminal. A +15V power supply (not shown) is connected to the power supply side of the electrode positioning setter 21 via the A contact 22a of the relay 22, and a relay 28 is connected to the connection point between the electrode positioning setter 21 and the A contact 22a. A -15V power supply (not shown) is connected via the A contact 28a. Further, in the welding power source l, the A contact 24a of the relay 24 is connected to the control power source (
(not shown). Furthermore, high frequency power supply 2
5 is connected between the tungsten electrode 2 and the base material 3, and the A contact 26a of the relay 26 is connected between the high frequency power source 25 and a control power source (not shown).

A series circuit consisting of a normally open welding start pushbutton switch 29, a normally closed welding stop pushbutton switch 30, and a relay 31 is connected between the busbars 27 and 28 connected to a control power source (not shown). , the A contact 81a of the relay 81 is connected in parallel with the welding start push button switch 29. Further, a series circuit of the B contact 15a of the relay 15 and the relay 22 is connected between the busbars 27 and 28, and a connection point between the busbar 27 on the busbar 27 and the welding start push button switch 29 and the busbar 2
A contact atb of relay at is connected between the connection point between contact 7 and contact B 15a. Further, a series circuit of the A contact 15b of the relay 15 and the timer 32 is connected between the bus bars 27 and 28, and furthermore, between the bus bars 27 and 28 (7)! JL/
A series circuit of -88tDA contact 88a and relay 38 is connected, and a connection point between A contact 15b and timer 82 and a connection point between A contact 88a and relay 33 are connected. Furthermore, the A contact 8 of the relay 33 is connected between the busbars 27 and 28.
1b is connected to a series circuit of the on-delay B contact 82a of the timer 32 and the relay 23; The series circuit with is connected in parallel.

Furthermore, the A contact 2 of the relay 24 is connected between the busbars 27 and 28.
4b and the A contact 6a of the relay 6 connected to the current detector 5
A series circuit of the relay 14 and the relay 14 is connected. Also, bus 2
During 7.28, A contact 24C of relay 24 and timer 3
Further, a series circuit between the A contact 24d of the relay 24, the on-delay B contact 84a of the timer 34, and the relay 26 is connected.

Now, when you press the welding start push button switch 29, the relay 31
is turned on and its A contact 81a closes, whereby the relay 31 is self-held.

When the relay 31 is in the on state, its A contact 81b is closed, and at this time, the relay 15 is in the off state, and the relay 22 is in the off state.
turns on. When the relay 22 is turned on, its A contact 22a closes, and the electrode positioning setter 21 is set to +1.
A DC voltage of 5 V is applied, and a positive setting voltage is output from the electrode positioning setting device 21. At this time, the relay 14 is in the OFF state and its B contact 14d is closed, so the output voltage signal of the electrode positioning setter 21 is input to the servo amplifier 20, and this signal is amplified by the servo amplifier 20. The control signal is inputted to the servo motor 10 as a control signal. At this time, since the output signal of the servo amplifier 20 is a constant positive voltage, the servo motor 10 rotates in the positive direction, causing its rotating shaft 11, pinion 9, rack 8. The tungsten electrode 2 is driven to descend at a constant speed via the support rod 7. When the tungsten electrode 2 descends at low speed and its tip contacts the groove 3a of the base material 3, the relay 14 is in the OFF state at this time, so the B
Contact 14a is closed, and diode 17 is connected from power supply 16.
, base material 3, tungsten electrode 2, coil 12. B contact L
4a, a current flows through the relay 15, and the relay 15 is turned on.

When the relay 15 is turned on, its B contact 15+1 is opened, so the relay 22 is turned off, and its A contact 22 is opened.
a opens, the positive voltage applied to the electrode positioning setter 21 disappears, and the servo motor 10 stops. relay 15
When is turned on, its A contact 15b closes, so
The timer 32 is not in the on state, and the relay 33 is in the on state and its A contact 38b is closed, and at this time,
Since the on-delay B contact 82a of the timer 82 is closed, the relay 23 is turned on. When the relay 23 is turned on, its A contact 23a closes, so a DC voltage of -15V is applied to the electrode positioning setter 21.
A negative set voltage is output from the electrode positioning setter 21. At this time, the relay 14 is in the off state υ and its B contact 14d is closed, so the output voltage signal of the electrode positioning setter 21 is input to the servo amplifier 20, and this signal is amplified by the servo amplifier 20. The signal becomes a control signal and is input to the servo motor 10. At this time, since the output signal of the servo balance 20 is a constant negative voltage, the tungsten electrode 2 is driven by the servo motor 10 to rise at a constant speed via the rotating shaft 11, pinion 9, rack 8, and support rod 7. be done.

When the timer 32 is turned on and a certain period of time has elapsed,
The on-delay B contact 82a opens and the relay 23 turns off, and the A contact 28a opens and the negative voltage applied to the electrode positioning setter 21 disappears. At this time, since the output signal of the servo amplifier 20 disappears, the servo motor 10 stops, and the tungsten electrode 2 stops rising.

The rising distance of the tungsten electrode 2 at this time is, for example, 3
It is about the same as steel. Furthermore, when the timer 32 is turned on and the above-mentioned certain period of time has elapsed, its on-delay A contact B2b is closed, the relay 24 is turned on, its A contact 24'& is closed, and this is used as a welding start command signal. Input to welding power source 1.

Electric power is supplied to the welding power source 1 from a power source (not shown), and welding is started. At this time, A contact 2 of relay 24
4c and 24d are closed, the timer 34 is turned on, and the relay 26 is turned on and its A contact 26a is closed. Electric power is supplied from a power source (not shown), a high frequency voltage is applied between the tungsten electrode 2 and the base material 8, and a spark discharge is generated between the tungsten electrode 2 and the base material 3. After a certain period of time has elapsed, the on-delay B contact 84a of the timer 34 opens, so the relay 26 turns off, and its A contact 26a opens, stopping the application of the high frequency voltage from the high frequency power source 25. Here, when an arc occurs between the tungsten electrode 2 and the base metal 3 and an arc current flows, the current detector 5 detects the arc current via the current transformer 4 and the relay 6 turns on. . When the relay 6 turns on, its A contact 6a closes, and at this time, the A contact 24b of the relay 24 closes.
is closed, so the relay 14 is turned on.

When the relay 14 is turned on, its B contact 14a opens and the connection between the tung stay electrode 2 and the power source 16 is cut off.
Further, the A contact 14b is closed, and the voltage signal between the tungsten electrode 2 and the base material 3 is input to the comparator 18. Furthermore, the A contact 14C closes and the comparator 18 and servo amplifier 2
0 is connected, and a signal corresponding to the deviation between the set voltage of the arc voltage setting device 19 and the obvious arc voltage between the tungsten electrode 2 and the base material 3 is inputted from the comparator 1B to the servo amplifier 20. Further, the B contact 14d opens, and the connection between the electrode positioning setter 21 and the servo amplifier 20 is cut off. In this state, arc voltage control (AVC control) is performed by the comparator 18, servo amplifier 20, and servo motor 10 so that the arc voltage between the tungsten electrode 2 and the base material 3 is always at an appropriate value.

When welding is completed and the welding stop push button switch 30 is pressed, the relay 31 is turned off and its A contacts ata and atb are turned off.
opens, the self-holding of the relay 81 is released, and the relays 22, 88, 2B, 24°14.26 and timer 32.84 are turned off, and the power supply to the welding power source 1 is stopped. , the arc between the tungsten electrode 2 and the base metal 3 is extinguished, and the circuit shown in FIGS. 1 and 2 returns to its initial state.

As explained above, in the tungsten electrode positioning device in the TIG automatic welding apparatus according to the present invention, at the start of welding, the tungsten electrode is lowered at a constant speed to contact the groove surface of the base material, and this contact is made with the tungsten electrode. Detected by the flow of current between the base material and the
Next, the tungsten electrode is raised at a constant speed until the distance between the tungsten electrode and the base metal reaches the optimum value, and then
I turned on the welding power and started welding.

The distance between the tungsten electrode and the groove surface of the base metal is kept at an optimum value, thus preventing short circuit between the electrode and the base metal, adhesion of spatter to the electrode tip, failure of transition from spark discharge to arc discharge, and failure of the electrode. Problems such as sticking into the molten pool can be eliminated, and the conventional complicated work required for positioning the electrode can be eliminated. In addition, conventional AV
Since it is only necessary to add a simple circuit to the C control control unit,
This device can be configured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the invention, and FIG. 2 is a circuit diagram showing an embodiment of the invention. 1... Welding power source, 2... Tungsten power source, 3...
・Base material, 7... Support rod, 8... Rack, 9... Pinion, lO... Servo motor, 11... Rotating shaft,
12... Coil, 13... Capacitor, 14a...
・B contact, 15...IJI/-116...Power supply, 1
7... Diode, 18... Comparator, 19... Arc voltage setting device, 20... Servo amplifier, 21...
Setting device for electrode positioning. Patent applicant: Kobe Steel Co., Ltd. Patent attorney Aoyama, 2 people

Claims (1)

[Claims] A tungsten electrode driving means for moving the tungsten electrode up and down, a lowering control means for giving a lowering command to the driving means to lower the tungsten electrode in response to a lowering start signal, and an electric current between the tungsten electrode and the base material. a detection means for detecting contact between the tungsten electrode and the base metal groove by detecting the flow of the tungsten electrode; 1. A tungsten electrode position setting device comprising: a rise control means for giving a rise command to the tungsten electrode; and a means for applying a welding voltage to the tungsten electrode when the tungsten electrode rises to a set position.