JPS5823188B2 - Method for regulating torch electrode protrusion length in automatic welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regulating the length of an electrode protrusion of a torch in an automatic welding apparatus that performs automatic welding while controlling the relative positions of a workpiece fixture and a torch using appropriate control means.

The present applicant previously filed Japanese Patent Application Publication No. 54-15441 and Japanese Patent Application No. 54-15441
No. 4-64853 presented an automatic welding device that uses the torch electrode itself as a sensor.

In this automatic welding device, a welding voltage and a sensor voltage are selectively applied to the electrodes of the torch through a special voltage application means according to a welding command or a sensor command from a control means as appropriate, and the electrodes and sensor voltages are applied selectively to the torch electrodes during sensing. This detects the current state between the workpiece and the weld line of the workpiece.

However, when a consumable electrode is used as the electrode, the length of the electrode protruding from the torch usually differs at the end of each weld due to the difference in the degree of penetration of the electrode during welding.

Additionally, the electrode between the electrode supply reel and the torch is generally inserted into a flexible tube, but in this case, the protruding length of the electrode is not necessarily constant due to changes in the bending state of the flexible tube as the torch moves. sensing in this state.

Even if this is done, the accurate welding line of the workpiece cannot be detected, so naturally good welding results cannot be expected from automatic welding performed based on such inaccurate sensing.

Therefore, when sensing the four weld lines on the workpiece after welding is completed, it is necessary to regulate the protruding length of the electrode of the torch to a predetermined length in advance of actual sensing.

Conventionally, this electrode protrusion length was regulated by setting a reference position on the outer edge of the workpiece fixture, and setting the virtual welding point at the tip of the torch based on a command from the control means with the torch electrode slightly retracted each time sensing was performed. Adjust the electrode to the reference position, send out the electrode in this state, and stop sending out the electrode by obtaining an energization signal between the electrode and workpiece fixture, or finish automatic welding at a certain part of the workpiece and move on to the next sensing. Before you do
The same procedure as described above was carried out near the previously programmed welding end point (often near the next sensing and welding point).

However, in the former case, the relative position of the workpiece fixture and the welding point of the torch must be controlled each time sensing is performed, which increases the time required for sensing, especially if the torch travels a long distance. In this case, the reference position of the workpiece set in advance for regulating the electrode protrusion length is not necessarily accurate for all workpieces due to errors in the processing and installation of individual workpieces, and the positional deviation error may occur. In any case, it was not always possible to obtain an accurate electrode protrusion length, as this appeared as an error in the protrusion length of the electrode.

In view of the above-mentioned circumstances, the present invention makes the tip of the torch mantle a conductor insulated from the electrode, and first retracts the electrode into the torch based on an electrode protrusion length regulation command from the control means, and then removes the electrode and the A voltage for the sensor was applied to the conductor at the tip of the torch jacket, and the torch was moved toward the flat part of the workpiece from a position appropriately away from the workpiece, and "current conduction" was detected between the flat part of the workpiece and the tip of the torch jacket. By the way, the torch is moved a predetermined distance away from the workpiece, and then the electrode is fed until it detects "current conduction" between the electrode and the workpiece. The present invention relates to a method for regulating the electrode protrusion length of a torch in an automatic welding device, the purpose of which is to be able to always regulate the protrusion length of the electrode to a constant value even if the protrusion length of the electrode differs from case to case.

Prior to a detailed explanation of the present invention, an automatic welding apparatus, which is the background of the present invention, will be sequentially explained.

In FIG. 1, the automatic welding device 1 moves the workpiece fixture 2 that fixes the workpiece W in the left-right direction (hereinafter referred to as the "X-axis direction").
・It is movable in the front-back direction (hereinafter referred to as the "X-axis direction") and rotatable around the horizontal axis H (hereinafter referred to as the "θ-axis direction"), and the torch mount 4 of the torch 3 can be moved in the vertical direction (hereinafter referred to as the "θ-axis direction").
The tool is configured to be movable in the "Z-axis direction" (hereinafter referred to as the "Z-axis direction") and swingable around the vertical axis (hereinafter referred to as the IF-axis direction), and controls the movement and rocking position of the workpiece W and the torch 3. A control means 5 is provided for the purpose.

Reference numeral 6 denotes a flat, square-shaped base, on one side of which a first frame 7 is fixed.

Reference numeral 8 denotes a trolley placed on the first frame 7, which is driven by an appropriate reduction gear and a forward/reverse motor with a brake (not shown), and is connected to the X-axis via an appropriate transmission means (not shown) such as a ball screw. It is possible to move in any direction.

Reference numeral 9 denotes a second frame fitted to the cart 8, which is movable in the X-axis direction by the same driving and transmission means as the cart 8, and the front end of the second frame 9 has a The aforementioned workpiece fixture 2 is rotatably attached to the holder.

10 is a vertical frame erected on the other side of the L shape of the base 6;
The aforementioned torch fixture 4 is attached to the tip of the horizontal arm 11 so as to be movable in the Z-axis direction and swingable in the W-axis direction.

The driving means for the horizontal arm 11 and the torch attachment 4 are both brake-sealing/reverse motors (not shown).

Further, the torch 3 has a welding point WP (
This point is a virtual point and does not always coincide with the tip of the electrode W) is attached to the tip of the torch mount 4 so that it is always on the vertical axis, and its attachment angle is In other words, the angle α formed by the central axis M with respect to the vertical axis is determined as appropriate depending on the type of welding to be performed (butt welding, fillet welding, etc.) and the shape of the workpiece W, but in special cases. Generally, the temperature is around 45 degrees.

12 is a power supply device for applying voltage and supplying current to the electrode W of the torch 3; 13.14 is a pair of electrode feeding rollers attached to the power supply device 12, respectively; is variable speed forward/reverse motor with brake 1
5 (FIG. 3).
4, the material is pulled out from the supply roll 13 and fed to the torch 3 through a flexible tube 16 formed with a loop-shaped deformed portion 16a (FIG. 3). .

Reference numeral 17 denotes a welding control instrument derived from the power supply device 12 and attached to the control means 5.

Reference numeral 18 denotes a remote control panel, which remotely controls the movement and rotation of the various parts by manual operation, and inputs a user program into the memory (not shown) in the control means 5 based on the remote control. It is.

FIGS. 2 and 3 are drawings relating to particularly important structural parts in carrying out the present invention, of which FIG. 2 is the same as described above.

A vertical cross-sectional view showing the details of the torch 3, and FIG. 3 is a schematic explanatory diagram mainly showing a circuit block diagram of the power supply device 12.

In FIG. 2, the main body 100 of the torch 3 includes the flexible tube 16 to receive the electrode W.

It consists of a proximal end socket 100a into which the electrode W is inserted, a hollow cylindrical body 100b containing a clamping mechanism 101 for the electrode W, and a tip electrode lead-out member 100c.

The clamp mechanism 101 includes a collet chuck 102 which is attached to the inner side of the proximal end socket t100a so as to be openable and closable, and a proximal diameter portion 103a and a distal end small diameter portion 103b which are connected to the inner circumferential surface 1oob1 and the central protrusion of the hollow cylindrical body 100b, respectively. 100b2 A tapered hole 103 slidably attached to the inner peripheral surface and cut at the tip of the large diameter portion 103a.
A1 is interposed between a single acting piston 103 which is engaged with a tapered portion 102a formed at the tip of the collet chuck 102, and the central protrusion 100b2 and the end of the small diameter portion 103b, so that the single acting piston 103 is always operated. and a compression spring 104 that biases toward the tip side (leftward in FIG. 2).

High-pressure gas (for example, high-pressure gas in a shield gas cylinder) flows into the cavity 105 formed between the central protrusion 100b2 and the large-diameter portion 103a through a hole 100b3 formed in the hollow cylinder 100b. and a gas feed pipe 106 for discharging the flexible tube 1.
The electrode W from 6 is inserted through the base end socket 100a, the single-acting piston 103, and the tip electrode lead-out member 100c along the central axis M of the torch 3, and when high pressure gas is not flowing into the cavity 105. In particular, as shown in FIG. 2, the single-acting piston 103 is in a position retracted toward the tip, loosening the collet chuck 102 to allow the movement of the electrode W, and when high-pressure gas flows into the cavity 105, the single-acting piston 103
is pushed toward the proximal end, and the electrode W is fixed in order to tighten the collet chuck 102.

The tip electrode lead-out member 100c is made of an electrically insulating material, and a ring-shaped jacket 107 made of a conductor having an outer diameter of a radius a centered on the central axis M is disposed at the tip thereof, and the jacket 107 is connected to the lead-out member. It is always insulated from the electrode W by 100c.

In FIG. 3, reference numerals 300 and 301 are voltage applying means and energization state detecting means built into the power supply device 12. Of these, the voltage applying means 300 has a welding power source 300a, a sensor power source 300b, and one end connected to the electrode W. a changeover switch 300c that connects and selectively connects to either of the side power supplies 300a, 300b at an appropriate time;
7, and a normally open on/off switch 300d, which is connected to the sensor power source 300b as appropriate.

Further, the energization state detection means 301 includes an energization state detection circuit 301a and an energization state detection output circuit 301b,
Among these, the energization state detection circuit 301a has one end connected to the sensor power source 300b, and the other end connected to the welding power source 300b.
The energization state detection output circuit 301b is connected to the workpiece W together with the opposite switch 300c side of the energization state detection circuit 301a.
(or a change in both voltages) is input as a detection signal and transmitted to the control means 5.

The following is a fourth explanation of the operation for regulating the length of the electrode protruding from the torch 3 in the automatic welding apparatus 1 configured as described above to a regular length.
This will be explained with reference to the operation explanatory diagrams in FIGS. 7 to 7 and the flowcharts in FIGS.

It is now assumed that the torch 3 is fixed to the torch fixture 4 at an attachment angle α, and the collet chuck 102 is in an open state.

Further, it is assumed that the regular protrusion length of the electrode W is the distance from the tip of the torch 3 to the welding point WP.

Furthermore, a microcomputer (not shown) built into the control means 5 is programmed with a series of operating commands such as electrode protrusion length regulation, sensing, and automatic welding, and the microcomputer is set to auto mode and activated. The above-mentioned program is output step by step as command information accordingly.

(1) First, it is determined whether the program includes an electrode protrusion length regulation command (FIG. 8).

(2) If included, the electrode W for the electrode feeding motor 15
Outputs a command to retract the appropriate amount.

The electrode W is rewound slightly by reverse rotation of the feed roller 14,
The electrode tip can be retracted into the torch 3.

(3) A command is output to the voltage applying means 300 to apply a sensor voltage to the electrode W and the jacket 107 of the torch 3.

Accordingly, the changeover switch 300c and the open/close switch 300d are both connected to the sensor power supply 300a,
A sensor voltage (usually high voltage and low current) is applied to the electrode W and the mantle 107.

(4) Output a command to control the position of the torch 3 to the start position.

The torch 3 moves appropriately in the X, Y, and Z axis directions, and welds the welding point W at a starting position Q appropriately above the horizontal member W1 of the workpiece W.
Stop with P matched (Fig. 4).

(5) Output a command to lower the torch 3 in the Z-axis direction.

The torch 3 descends toward the horizontal member W1.

(6) When the mantle 107 of the torch 3 comes close to the upper surface f1 of the horizontal member W1 during the lowering, electricity is applied between the two, and the energization state detection circuit 301a detects a change in voltage and/or current, and the energization state is detected by the energization state detection circuit 301a. The state detection output circuit 301b issues an "energization" signal, and the torch 3 stops descending.

(Figure 5). (7) Output a command to raise the torch 3 a predetermined distance in the Z-axis direction.

Torch 3 rises by the distance and stops at that position.
(Figure), the mantle 107 naturally separates from the horizontal member W1, and no current is passed between them.

At this time, the distance is programmed in advance as (bco, sα-asinα) from the mounting angle α of the torch 3, the radius a of the jacket 107 of the torch 3, and the standard protrusion length b of the electrode W. , welding point WP as shown in Figure 6.
corresponds to the upper surface f1 of the horizontal member W1.

(8) A command to feed the electrode W is output to the electrode feeding motor 15.

The electrode W protrudes from the torch 3 by forward rotation of the feed roller 14.

(9) During the electrode feeding, if the tip of the electrode W comes close to the upper surface f1 of the horizontal member W1, electricity will flow between the two, and the current will be passed through the energization state detection output circuit 301 via the energization state detection circuit 301a.
An "energization" signal is issued from b, and the drive of the electrode feeding motor 15 is stopped to stop the feeding movement of the electrode W (FIG. 7).

00) A command is output to the clamp mechanism 101 in the torch 3 to tighten the electrode W.

High-pressure gas flows into the cavity 105 from the gas supply pipe 106, and the single-acting piston 103b moves to the right in FIG. 2 to close the collet chuck 102, thereby tightening the electrode W. Fix it.

αD Based on the above, it is determined that the electrode protrusion length regulation is completed, and the command to the voltage application means 300 in step (3) is deleted.

At this time, only the open/close switch 300d performs the opening operation,
The changeover switch 300c remains connected to the sensor power source 300a until it receives a "welding command" from the control means 5.

This completes the step of regulating the electrode protrusion length, and the protrusion length of the electrode W from the torch 3 is accurately regulated to b, and the electrode tip coincides with the welding point WP.

Thereafter, the torch 3 is moved as appropriate and stands by at that position until the next sensing command or welding command is issued.

In reality, the electrode tip may be shifted away from the welding point WP in consideration of the material, plate thickness, welding conditions, etc. of the workpiece W, and in this case, the above-mentioned distance must be set h' (
= h−△h).

Further, in the above-mentioned embodiment, the electrode W was retracted into the torch 3 in step (2), but this step can be carried out in the same way even when the program moves to the final step of the automatic welding system program.

In this case, each time the automatic welding operation is completed, the electrode W is
It is something that can be drawn inside.

Further, the electrode protrusion length regulating method of the present invention can be applied to a torch in which the torch fixture 4 does not swing or the welding point WP does not need to be placed on the vertical axis. , the Y-axis direction is horizontal and the Z-axis direction is vertical, but it is possible to carry out the implementation by replacing these three axes in any way as long as they are perpendicular to each other.

Further, the power supply device 12 can also be used as a power supply device 400 having a control circuit as shown in FIG. 10 to regulate the electrode protrusion length by the method of the present invention.

That is, in FIG. 10, the power supply device 400 is roughly divided into three control blocks: voltage application means 401, electrode feeding means 402, and energization state detection means 403.

The voltage application means 401 receives the voltage from the control means 500.
It emits a signal in response to either a "welding command", a "sensor command", or an "electrode protrusion length regulation command".

It includes a welding command signal generation circuit 404, a sensor command signal generation circuit 405, and an electrode protrusion length regulation command signal generation circuit 406.

Among these, the output of the circuit 404 is the output voltage setting circuit 4 for welding.
07, and the outputs of the circuits 405 and 406 pass through the sensor output voltage setting circuit 408 and are then output to the output voltage control circuit 4.
09, a preset welding output voltage or sensor output voltage (this voltage also serves as an output voltage for electrode protrusion length regulation) is applied to the electrode W via the thyrisk rectifier stack 410, but the circuit 406 At the same time, the output from the torch 503 is applied to the tip conductor 503a of the torch 503 via a voltage application regulation circuit 411 that allows voltage application.

Further, the electrode feeding means 402 includes an electrode feeding amount setting circuit 4
12. Consists of an electrode feeding motor control circuit 413, an electrode feeding motor 414, and an electrode feeding motor braking circuit 415, and the electrode feeding motor braking circuit 415 receives the welding command signal generation circuit 404 or the electrode protrusion length regulation command. Only while a "welding command" or "electrode protrusion length regulation command" signal is being input from the signal generation circuit 406, the braking of the electrode feeding motor 414 is released and the electrode is moved in the direction of the command from the control means 500. The feeding motor 414 is driven, and the electrode W is drawn out from the electrode feeding roll 513 at a preset speed by forward or reverse rotation of the electrode feeding roller 514 and fed to the torch 503, or the electrode W is fed from the torch 503 to the torch 503. It takes the electrode W to the supply roll 513.

Further, the energization state detecting means 403 includes an energization state detection circuit 416 and an energization state detection output circuit 417, of which the detection circuit 416 is connected to an appropriate cutoff circuit (not shown).
When a "welding command" signal is input from the welding command signal generation circuit 404, it is deactivated via the cutoff circuit, and the electrode W and the tip of the torch 503 are turned off only when sensing and when regulating the protruding length of the electrode. The energization state (change in current and/or voltage) caused by the close discharge between the part conductor 503a and the workpiece W is detected, and the detection signal is transmitted to the control means 500 via the energization state detection output circuit 417. It is.

Regulation of the electrode protrusion length when using the power supply device 400 configured as described above is performed according to the flowchart of subroutine 1' in FIG. 11 instead of subroutine 1 in FIG. 10, and a detailed explanation of the operation will be given here. Omitted.

As described in detail above, the method for regulating the protruding length of the electrode of the torch according to the present invention is to fix the torch in one direction of movement, and to fix the torch so that the central axis forms a predetermined acute angle with respect to the direction. Voltages are applied separately to the electrode and the torch tip conductor, first the electrode is retracted into the torch, and then the torch is moved toward the workpiece plane perpendicular to the direction of movement, with the tip conductor The flat surface of the workpiece is detected, the torch is then moved a predetermined distance away from the flat surface of the workpiece, and from this state the electrode is protruded to the point where it detects the flat surface of the workpiece to obtain the standard protrusion length, which reduces machining errors for individual workpieces. Even if there is an error in mounting the electrode to a workpiece fixture, an accurate electrode protrusion length can always be obtained.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view of an automatic welding device as an example of implementing the method for regulating the protruding length of a torch electrode according to the present invention, Fig. 2 is an enlarged vertical sectional view of the torch, and Fig. 3 is a circuit configuration of a power supply device. A schematic explanatory diagram mainly based on
, 9 is a flowchart, FIG. 10 is a schematic explanatory diagram mainly showing the circuit configuration of another power supply device, and FIG. 11 is a flowchart when the power supply device of FIG. 10 is used. In the figure, 1 is an automatic welding device, 3 is a torch, 5 is a control means,
12 is a power supply device, and W is a workpiece.

Claims (1)

[Scope of Claims] 1. A workpiece fixture and a torch whose relative positions are controlled by appropriate control means, and welding and sensor voltages are selectively applied to the electrodes of the torch according to commands from the control means. and means for detecting the energization state of the electrode, and in the welding path, the protruding length of the electrode is equal to or less than the regular length, wherein the torch has a mantle at its tip as a conductor insulated from the electrode. , the voltage applying means is configured to be able to apply a sensor voltage to the mantle, and when adjusting the electrode protrusion length, the central axis of the torch is held at an acute angle α with respect to a predetermined movement direction; A sensor voltage is applied to the electrode and the jacket, the workpiece fixture or the torch is moved in the predetermined movement direction in which the torch approaches the workpiece flat part, and the energization is performed when a proximity discharge occurs between the workpiece flat part and the jacket. The workpiece fixture or the torch is moved a predetermined distance in the predetermined movement direction away from each other in response to an "energization" signal from the state detection means, and then the electrode is fed to the point where a close discharge occurs between the electrode and the workpiece. A method for regulating the protruding length of a torch electrode in an automatic welding device, characterized by: 2. The voltage applying means includes a welding power source and a sensor power source,
A torch in the automatic welding apparatus according to claim 1, further comprising a changeover switch for selectively connecting the electrode to the both type sources, and an opening/closing switch for connecting the mantle to the sensor power source at appropriate times. Method for regulating electrode protrusion length. 3. The voltage application means is built in one power supply device,
Selectively outputs one of the welding command signal generation circuit, sensor command signal generation circuit, electrode protrusion length regulation command signal generation circuit, welding output voltage setting circuit, sensor output voltage setting circuit, and both output voltage setting circuits. and apply the output voltage to the electrode, and apply the output voltage for the sensor to the mantle through the voltage application regulation circuit as appropriate only when an electrode protrusion length regulation command is issued from the control means. A method for regulating the length of an electrode protrusion of a torch in an automatic welding apparatus according to claim 1, comprising a control circuit. 4. The energization state detection means includes an energization state detection circuit that detects a change in current and/or voltage due to discharge in the proximity of the workpiece and the electrode or torch jacket, and transmits signal information from the circuit to the control means. A method for regulating the protrusion length of a torch electrode in an automatic welding apparatus according to claim 1, comprising: an energization state detection output circuit; 5. The method for regulating the length of an electrode protrusion of a torch in an automatic welding apparatus according to claim 1, wherein the predetermined distance is equal to b cos α - asin α. However, a is the distance from the central axis of the torch to the part of the torch mantle closest to the workpiece, and b is the normal protrusion length of the electrode protruding from the tip of the torch.