JPS5930510B2 - automatic welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic welding device, and more particularly to an automatic welding device that uses a welding torch as a weld line detector (sensor).

The positions of the welding torch and the workpiece are mutually controlled in space according to the position information and control information stored in the storage device,
A playback type automatic welding device that automatically performs welding according to a program is well known.

It is known that a sensor is used to cause the welding torch to follow the welding line of the workpiece. However, conventionally, a sensor for detecting a welding line has been attached separately from the torch and in the vicinity of the torch, resulting in a large size around the torch. Therefore, the torch or sensor cannot fit into the back of a narrow workpiece.
The sensor does not work effectively when the groove size of the weld line is small. In addition, there were various problems such as the structure being complicated and expensive. Therefore, the present inventors have previously proposed an extremely superior automatic welding device in which the torch itself acts as a sensor. In such a proposed automatic welding device, a detection power source different from a normal welding power source is connected between the torch electrode and the workpiece, and the energization state between the torch, that is, the electrode and the workpiece is detected at this time. It is designed to detect.

However, in such a proposed automatic welding device, if a consumable electrode is used as the electrode, the length of the projection from the torch is not necessarily strictly constant at the end of welding. Furthermore, when a flexible tube is connected between a fixed ablation electrode supply means and a moving torch, and the consumable electrode is passed through the flexible tube, as is widely done, as the torch moves, There is a possibility that the above-mentioned protrusion length may change.
Therefore, this protrusion length is not necessarily constant at the start of work. Therefore, the main object of the present invention is to provide an automatic welding device of a consumable electrode type that uses a welding torch as a sensor, in which the length of the consumable electrode protruding from the torch can be made constant. .

In summary, the present invention comprises a workpiece fixture and a consumable electrode type torch whose movement is controlled by a control means and whose mutual position is controlled, and a consumable electrode cutting means, such as The automatic welding apparatus is equipped with a rotating grindstone, and the control means operates the cutting means after a constant operation of the consumable electrode supply means.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

Before describing embodiments of the present invention, an automatic welding apparatus that is a background of the present invention and is effective in carrying out the present invention will be described.

However, it should be pointed out in advance that the present invention is not limited to such embodiments. FIG. 1 is an overall perspective view showing an example of an automatic welding apparatus to which the present invention is applied and which forms the background of the present invention.

In FIG. 1, this automatic welding apparatus 100 includes a work W
The torch 10 is configured so that the fixture 105 (not shown) can be moved left and right, front and back, or rotated around the horizontal axis H.
Each of the fixtures 108 of 9 is configured to be able to move up and down or rotate around the vertical axis L, and
A control box 400 including a general-purpose computer for automatically controlling the movement and rotational position of the torch 109 is provided. Let me explain in more detail. First, a displacement mechanism for displacing the relative positions of the torch 109 and the workpiece fixture 105 will be described. A first frame 102 is fixed to one side of the L-shaped floor plate 101 in plan view.

A cart 103 that is movable in the left-right direction (X-axis direction in the figure) is provided on the top of the frame 102. The power means (not shown) of this truck 103 is a known motor with a brake equipped with a reduction gear in this embodiment, and the power transmission means (not shown) is a well-known engagement between a ball nut and a threaded rod. means (so-called ball screw).Also,
A second frame 104 that is movable in the front-rear direction (Y-axis direction in the figure) is provided on the upper part of the truck 10.3. The power means and power transmission means of this frame 104 are also a similar motor with a brake and a ball screw, although not shown. A workpiece holder 105 is provided at the front of the frame 104 and is rotatable in the θ-axis direction in the figure. Although not shown, the power means of this workpiece fixture 105 is also a known motor with a brake and a reduction gear. A third frame 106 is erected at the other end of the floorboard 101 .

This frame body 106 has a vertical direction (z-axis direction in the figure).
A movable arm 107 is provided. The power means and power transmission means of this arm 107 are also a similar motor with a brake and a ball screw, although not shown. The distal end of the arm 107 is arranged around the vertical axis L (
A fixture 108 for a torch 109 is provided which is rotatable in the θ-axis direction in the figure. Although not shown, the power means of this torch mount 108 is also a known motor with a brake and a reduction gear. In addition, the installation position of the torch 109 is
The welding point WP on the extension of the center line of the torch 109 is configured to coincide with the vertical axis L, and the mounting angle is determined depending on the welding mode to be performed (butt welding, fillet welding, etc.) and the workpiece. shall be optimally selected according to the shape of the Although the displacement mechanism is realized with the above configuration, this is just an example and is not limited to the above configuration.

Furthermore, a current is supplied to the torch 109 from a power supply device 200, which is an example of a power supply means.

The control box 400 and the welding control device 300 automatically control the forward rotation, reverse rotation, moving speed, welding current, etc. of the power means (motor with a brake equipped with a speed reducer) of each part according to the Pukagram, and the welding The mutual positions of the two fixtures 105 and 108 are controlled so that the point WP is along the welding line of the workpiece W (not shown) and automatic welding can be performed in the position with the best welding conditions. A remote control ("remote control") panel 500 is provided for the purpose of creating a program or for manual operation.In this embodiment, the welding point WP on the extension of the center line of the torch 109 is located on the vertical axis L. Since it is configured to match the above, it remains constant regardless of the rotation of the fixture 108 in the θ-axis direction, and the posture of the torch 109 with respect to the same welding point can be changed arbitrarily depending on the rotation of the fixture 108 (in the θ-axis direction). can be changed to

That is, this embodiment is an automatic welding device with five degrees of freedom. In this embodiment, a consumable electrode cutting means 110 is further provided at the upper end of the frame 104.

This consumable electrode cutting means 110 includes a grindstone 111 and a motor 112 for rotationally driving the grindstone. This motor 1
12 can be controlled to rotate and stop by a control means included in the control box 400. For example, the consumable electrode 209 supplied from the grinding wheel 111 is connected to the collector chuck 10.
It is led out to the tip of the torch 109 through the hollow part 9a. Normally, the piston 109b is moved by the spring 109e.
The collector chuck 109a is biased to the left in the figure.
is open. Therefore, the consumable electrode 209 can freely move within the welding torch 109.
For example, in sensing mode, when it is necessary to clamp the consumable electrode 209, the piston 109b is pushed to the right in the figure by supplying high pressure fluid from the tube 109d. Therefore, the collection chuck 109a is tightened by the inner periphery of the tip of the piston 109b, and the consumable electrode 209 is clamped. FIG. 11 is a schematic block diagram showing an electric circuit of an automatic welding apparatus according to an embodiment of the present invention described above. In the figure, a control box 400 includes a computer 401, an interface 404, and servo circuits SX, SY, Sθ, SZ, S
Including Φ. Computer 401 is a so-called microcomputer and includes a CPU, ROM, and RAM. R
The OM stores operating programs as shown in FIGS. 5 and 7, which will be described later. The CPU operates according to this operating program. The RAM stores various calculation information, teaching information, and the like. Each servo circuit SX, SY, Sθ, SZ, SΦ is
Motors MX, MY, Mθ, MZ, for displacing each axis,
This is a circuit for driving MΦ. The aforementioned sensor 207
The output is read into the computer 401 via the interface 404. Further, command data from remote control panel 500 is read into computer 401 via interface 404 . On the other hand, a switching command signal is given from the computer 401 to the switch 204 via the interface 404. The sensing operation for using the welding torch as a sensor will be described below with reference to FIGS. 4 to 7. Prior to this sensing operation, in this invention,
Furthermore, perform the following operations.

That is, the consumable electrode cutting means 110 as shown in FIG.
As a result, the protruding length of the consumable electrode 209 protruding from the torch 109 is made constant. To this end, the control means included in the control box 400 first positions the workpiece fixture 105 and therefore the consumable electrode cutting means 110 in the X-axis direction and Y-axis direction at a predetermined position (a certain distance from the third frame 106). Control position. Thereafter, the z-axis direction of arm 107 is controlled. Subsequently, the supply means 201 is controlled to supply a certain amount of the consumable electrode 209.
is made to protrude from the tip of this torch 109. Then, as shown in FIG. 10, a certain position of the side surface of the ablation-erasing electrode 209 protruding from the tip of the torch 109 faces the peripheral edge, that is, the cutting edge of the rotary grindstone 111. Then, the consumable electrode 209 is clamped by the collection chuck a using the piston 109b shown in FIG. After that, motor 11
When a drive command is given to the torch 10 to rotate the whetstone 111 and bring the whetstone 111 into contact with the consumable electrode 209,
The deworming electrode 209 protruding from the main body of 9 is cut to a certain length. In this way, even if the torch 109 is rotated, the electrode 20 protruding from the torch 109 can be
The length of 9 can always be kept constant. Therefore, more accurate sensing can be performed when sensing the weld line. The above operations are performed by the computer 401 included in the control box 400.
01 functions as a protrusion length constant means. In addition, in the above-mentioned embodiment, the inflow of high pressure fluid through the pipe 109d,
The discharge may be performed by manually operating a switching valve (not shown), or the switching valve may be automatically switched by a signal from a program.

In this way, prior to sensing the weld line, the length of the consumable electrode protruding from the welding torch is made constant, and then
Moving on to the sensing operation described below.

In this sensing operation, the computer 401 in the control box 400 functions as a sensing means. Now, with reference to the flowchart in FIG. 5 for automatically controlling the welding point WP of the torch 109 from point P6 to point P7 for the Y-axis direction welding line WL of the workpiece W (1) as shown in FIG. 4. Let us describe its effect.

First, the computer (not shown) in the control box 400 is set to teaching mode, and by manually operating the operation buttons (not shown) on the panel 500, the welding point WP of the torch 109 is changed from point P1 to point P6 to point P7 using a known playback method. At point P, the Φ angle is Φ where the torch is in the XZ plane.
1 and the sensor command at point P6.
At step 7, welding commands are each input into the computer as a user program. Then, the computer is set to auto mode, and a start button (not shown) is manually operated. Then, the contents of the first step of the user program are stored and output.

Its content is as a position command for the torch 109, point P1 (X
l, Yl, Zl, Φ1) are commanded. Accordingly, the mutual positions of the torch 109 and the workpiece W are automatically controlled, the position of the welding point WP of the torch 109 reaches the point P1, the Φ angle becomes Φ1, and the arrival signal is returned to the computer to proceed to the next step. The contents of are stored and output. The content is that the next position command of the torch 109 is point P6 (X2, Yl, Z2, Φ
1) and a sensor command. In response to this sensor command, a command to the changeover switch 204 is outputted according to a system program that has been separately input into the computer in advance, and the switch 204 is thereby switched.

Similarly, the system program outputs a command to lower the Z axis, that is, a command to lower the torch 109, and the torch 109 descends. Since a high voltage potential difference is operated between the electrode of the torch 109 and the workpiece w by the power source 206, the tip of the electrode of the torch 109 is at the point P2.
(The maximum distance between the workpiece W and the tip of the electrode is about 2 mm), a spark flies between them. Thus, the sensor 207 detects this current, and based on the signal, Zs of the position information of the current position P2 is taken in, and the computer calculates the difference ΔZ between this value and Z2 of the command information for this step. At the same time, the system program allows the torch 109
is raised by a certain amount (1 to 2 mm) to reach point P3.
Then, the computer shows that the Φ angle is Φ1 and that X1 and
2, the next sensing direction
(rightward in the figure), a command to move the workpiece W in that direction is output, and the workpiece W moves to the right.

In the same way as described above, when the electrode and the workpiece W approach each other and a spark flies at the point P4, the difference ΔX between the X-direction position Xs of P4 at that time and the command X2 is calculated. Then, the workpiece w is returned by a certain amount to reach a point P5. In this way, it is determined that sensing is complete, and based on that information, the previous command to the switch 204 is erased, and the switch 204 returns to its original state. Therefore, the point P6 (X2, Yl, Z2,
The position command to Φ1) is executed, but at this time, the above-determined ΔZ and ΔX are corrected, that is, the point P
'6 (X2+ΔX, Yl, Z2+ΔZ, Φ1), and the welding point WP of the torch 109 is set to the welding line W.
The position is controlled correctly to the starting point of L. Then, due to the arrival signal similar to that described above, the next step, that is, point P7 (X2
, Y2, Z2, Φ1), point P7 (X2+ΔX, Y2, Z
2+ΔZ, Φ1) is output, and a welding command is also output, and the torch 109 executes welding while moving linearly from point P6 to point P7'.

In this way, even if the welding line WL deviates from the initially programmed position, the starting point position is detected and the commanded position is moved in parallel to correct it.

In the above description, the relative position of the tip of the consumable electrode with respect to the torch 109 is such that the consumable electrode always protrudes from the torch 109 in the same shape due to the action of the force device 202, and the protrusion length is the same as that at the start of sensing. It will be understood that since they are always the same, they will always be in the same relative position and will not interfere with the above-mentioned function as a sensor.

Note that by flowing gas (for example, CO2) through the torch 109, more stable sensing can be performed. Furthermore, it will be understood that this embodiment can be applied when the angle formed by the two side surfaces constituting the weld line WL is known in advance (in this case, it is a right angle).

Next, with reference to FIGS. 6 and 7, another embodiment will be described, highlighting the differences from the previous embodiment.

Note that this embodiment can be applied when the angle formed by the two side surfaces constituting the weld line WL is not known in advance. The welding line WL in the X-axis direction in this embodiment is a butt welding line having a groove, which is intended to be welded downward, and the torch 109 maintains a vertical posture.

The teaching steps in this case are the first
As a step, position information
1, Yl, Zl and the sensing direction -X (also used as a sensor command).

As a second step, position information Xl, Y2, Zl is obtained from the position of point P1 to the point P above the terminal end of the welding line WL in the Y-axis direction.
and input the sensing direction -X. As a third step, a command to implement the position information of point P8 sensed in the first step and a sensing completion command are input. Furthermore, in the fourth step, a command for implementing the position information of the point PIO sensed in the second step and a welding command are input. The execution of the above user program will be described below.

First, in the first step, the torch 109 and the workpiece W are
The positions of the torch 1 are mutually controlled, and the torch 1 is placed at the position P shown in FIG.
09 is controlled. Since this step includes a sensor command, a command to the changeover switch 204 is output, whereby the switch 204 is switched and a high voltage is applied between the electrode of the torch 109 and the workpiece W. Then, a command to lower the Z axis, that is, a command to lower the torch 109, is output, and the torch 109 descends. Then, at point P2 (Xl, Yl, Z2), a spark flies and the output signal from sensor 207 is input to the computer. In response to this input signal, the computer takes in the position information Xl, Yl, Z2 of this point P2 and stores it in a certain predetermined location. Next, since the sensor command is sensing direction -X, determine the sensing direction from that,
(In this case, move the workpiece to the right.) Output the movement command.

Then, a spark flies at point P3 (X2, Y,, Z2), and the signal from sensor 207 is input manually to the computer. The position information of this point P3 is taken in by this human input signal and stored in a certain predetermined location. Next, a command is output to return the workpiece W by a certain amount (appropriately determined depending on the size of the welding line WL) in the opposite direction to the previous movement in the X-axis direction, that is, in this case, the workpiece W moves slightly to the left. When the point P4 (X3, Yl, Z2) is reached, a command to lower the Z axis is output again, and the torch 109 is lowered.

Then, at point P5 (X3, Y,, Z3), the sensor 20
The signal No. 7 is input to the computer, and the position information of this point P5 is taken in and stored in a certain predetermined location. Furthermore, a command to move the workpiece W to the left (in the same direction as the previous movement in the X direction) is output, and furthermore, the signal from the sensor 207 is input to the computer at point P6 (X4, Yl, Z3). Capture and import location information and store it as well.

Thus, by storing the four pieces of position information by inputting the signal of the sensor 207 four times, it is determined that sensing is complete, and the intersection of the line connecting point P2P6 and the line connecting point P3P5 is calculated to obtain point P7. .

Then, calculate the aiming position of the torch 109 (usually slightly above point P7) P8 (X5, Yl, Z4) from point P7, and store it at the determined position. This completes this step. Become. The next step is point P9 (Xl,
Y2, Zl) and includes a sensor command.

Therefore, in the same way as in the previous step, the aiming position PlO(X6, Y2
, Z5) is calculated and stored. Furthermore, in the next step, the position information of point P8 stored in the first step is called up and executed.

At this time, since the sensing completion command is also included, the previous command to the changeover switch is erased, the switch 204 returns to its original state, and a welding voltage is applied between the torch 109 and the workpiece W. In the next step, the second
Since the point PIO memorized in the step is given a position command and a welding command is given, the workpiece W moves in the Y-axis direction, that is, relatively
The machine moves while performing welding and performs automatic welding.

According to this embodiment, even if the welding line WL is formed by a groove having an undefined shape, the intersection of the side surfaces of the weld line WL is calculated and the groove shape is determined, thereby achieving a good welding result. It is possible to determine the target welding position.

Further, although this embodiment has been described with respect to a straight welding line WL, even if the welding line WL is bent,
All the aiming positions of the torch 109 at the starting point, each bending point, and the ending point may be calculated in advance, and each point may be sequentially executed by PTP control. Furthermore, in the above embodiment, the welding power source 205 and the detection high voltage power source 206 are switched by the mechanical changeover switch 204, but this is not possible as shown in FIG. 8 or 9. Examples are also possible.

In FIG. 8, a welding power source 205 is applied to a voltage applying means 203, that is, a consumable electrode 209, through a unidirectional element 205a such as a diode.

The detection power supply 206 is connected to this diode 205a.
connected to the output side of the Here, the detection power supply 206 is
For example, an oscillator is used that generates a high frequency voltage and is activated in the sensing mode. Therefore, in the example of FIG. 8, in the sensing mode, the voltage from the welding power source 205 and the detection power source 2
The high frequency voltage from 06 is superimposed and applied to the consumable electrode 209. In addition, in welding mode,
The power supply 206 may be disabled. In the embodiment shown in FIG. 9, the welding power source 205 is connected to the voltage applying means 203 via a current limiting resistor 206a.

A changeover switch 204a is connected in parallel to this current limiting resistor 206a.

In the welding mode, this switch 204a
is closed to shunt the current limiting resistor 206a. Therefore, the output from the welding power source 205 is directly applied to the consumable electrode 209. In the sensing mode, the changeover switch 204a is opened and the current limiting resistor 206a is enabled. Therefore, in this sensing mode, the voltage from the welding power source 205 is applied to the deterioration electrode 209 via the resistor 206a. Due to the action of this current limiting resistor 206a, only an extremely smaller current flows in the sensing mode than during welding. It goes without saying that the cutting means used in the present invention may be scissors or a cutter in addition to the rotary grindstone.

As described above, according to the present invention, the consumable electrode protruding from the welding torch is cut before performing the sensing operation to make the protrusion length constant, so that sensing can be performed with great accuracy.

Furthermore, according to the present invention, the predetermined welding point position is sensed before automatic welding, so even if the workpiece is changed, the welding start and end points are automatically sensed.

Therefore, during playback, there is no need to manually control the relative positions of the workpiece and the torch as in the past, and the working time can be shortened.

[Brief explanation of the drawing]

FIG. 1 shows an overall perspective view of an automatic welding device that forms the background of this invention and in which this invention can be effectively implemented. FIG. 2 is a partially illustrative view relating to the consumable electrode supply means. FIG. 3 is a longitudinal sectional view showing the welding torch 109 in detail. FIG. 4 is an illustrative view showing one form of a weld line sensed by the present invention. FIG. 5 is a flow diagram showing the sensing operation in the case of FIG. FIG. 6 is an illustrative view showing another form of the weld line sensed by the present invention. FIG. 7 is a flow diagram showing the sensing operation in the case of FIG. FIGS. 8 and 9 are schematic diagrams showing other embodiments for switching to a welding power source and a detection power source, respectively. Figure 10 shows the consumable electrode 209
FIG. 2 is an illustrative view showing a state in which the cutting means 110 and the cutting means 110 are opposed to each other. FIG. 11 is a schematic block diagram showing an electric circuit of an automatic welding apparatus according to an embodiment of the present invention. In the figure, 100 is an automatic welding device, 107 is an arm, 105 is a workpiece fixture, and 10
9 is a torch, 201 is a consumable electrode supply means, 204 is a changeover switch, 205 is a welding power source, 206 is a detection power source,
207 is a current sensor, 209 is a consumable electrode, 109a is a collection chuck, 109b is a piston, 109c is a cylinder, and 110 is a consumable electrode cutting means.

Claims (1)

[Scope of Claims] 1. A welding torch including a consumable electrode supplied from a consumable electrode supply means and a work fixture for attaching a work, and after sensing a predetermined welding point position of the work, the welding torch and The automatic welding device automatically welds the welding line of the workpiece by controlling the position relative to the workpiece fixture, the automatic welding device being coupled to the electrode of the welding torch and supplying electric power to the electrode of the welding torch. a displacement mechanism for displacing the relative position of the welding torch and the workpiece fixture; a sensing means for performing the sensing; and a displacement mechanism for displacing the relative position of the welding torch and the workpiece fixture. a consumable electrode cutting means for cutting the consumable electrode which is displaced and protrudes from the welding torch; and a consumable electrode cutting means for cutting the consumable electrode protruding from the welding torch by the displacement mechanism before sensing by the sensing means. The relative position is positioned and controlled, the consumable electrode is made to protrude by the consumable electrode supply means, and the tip of the protruded consumable electrode is cut by the consumable electrode cutting means, thereby causing the consumable electrode to protrude. Protrusion length constant means is provided to make the length constant, and the sensing means gives a movement command to the displacement mechanism in order to bring the consumable electrode and the workpiece closer together at a plurality of point positions across the welding line. , detecting the energization state of the consumable electrode, and generating data representing the mutual position of the welding torch and the workpiece at that time in response to the output of the energization state detection means at the plurality of point positions; An automatic welding device comprising means for calculating the predetermined welding point position based on the data at the plurality of point positions. 2. Claim 1, wherein the cutting means is a rotating grindstone.
Automatic welding equipment as described in section. 3. The automatic welding apparatus according to claim 1 or 2, wherein the welding torch further comprises means for clamping the consumable electrode at its base end.