JPS58145368A - Fillet copying welding device - Google Patents

Abstract

PURPOSE:To make a device simple, light and compact in a device in which a welding torch is mounted on a running truck by enabling the controlling unit to control plural elements by a sensor. CONSTITUTION:A controlling unit C controls motors M1-M5 and a welding power source WS, and is constituted mainly of a computer including a central processing unit CPU and a memory MEM. Motors M1-M5, encoders E1-E5, a sensor S1, a detector S2 and the power source WS are connected to the controlling unit through a pass line B. The controlling unit C includes the first device that controls a moving body 6 by output information of the sensor S1 to make the output value of the sensor S1 nearly constant, the second device that controls rotation of the mechanism 9 to make the angle of the torch 7 to the weld line WL constant, the third device that controls the speed of a truck 1 to make welding speed constant, and the fourth device that steers all wheels to make the distance between the weld line WL and the truck 1 nearly constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for performing fillet welding by mounting a welding torch on a traveling truck whose wheels can be steered.

There are various conventional profile welding devices, but all of them are designed to control one element using the output of one profile sensor, so the more elements there are to control, the more must also be increased. Therefore, the structure of the welding device becomes complicated and becomes large.

This invention has been made in view of the above-mentioned circumstances, and aims to provide a fillet profile welding device in which only one profile sensor is provided and multiple elements can be controlled by a control device, Examples will be described in detail below.

W, , W2 are workpieces, W is a horizontal plate, and W2 is a vertical plate. The works W1*W2 are positioned relative to each other as shown in FIG. 4, and tack welded in advance. WL (WL1 to WL3) are weld lines formed by both plate materials w1 and W2, respectively. .

1 is a traveling trolley (in the embodiment, the planar shape is square), and a total of four wheels 2 are mounted on it. In addition, all wheels 2 are
Chain 8a is activated by electric motor M1 attached to the bottom of trolley 1.
and sprocket) 8b, 8C, and bevel gears 8d, 8e
It is configured to be driven in the same direction via a power transmission mechanism 8 consisting of. Although the details are not shown, E is an encoder for detecting the traveling distance connected to the wheel 2.

4 is a steering mechanism and an electric motor M attached to the bottom of the truck L
2, the chain 4a and sprockets 4b, 4
1. via c. It is constructed so that all wheels 2 can be steered in the same direction at the same time. E2 is a steering angle detection encoder of the mechanism 4, although details are not shown.

Reference numeral 5 denotes a rotating body that is vertically supported 5a at the upper center of the truck 1 and rotated by an electric motor M3 (not shown). .

Although E3 is not shown in detail, it is an encoder for detecting the rotation angle of the rotating body 5.

6 is a movable body supported by the rotating body 5 and movable in the horizontal direction via the electric motor 1 and a known ball screw set transmission mechanism 7. E4 is an encoder for detecting the position of the moving body 6.

Reference numeral 8 denotes a rotating member whose one end is horizontally connected 8a to the distal end of the movable body 6.

9 is vertically supported by the lower part of the member 8 in the horizontal state, and its tip end is at an imaginary point (in the embodiment, a shaft 10b to be described later).
), and in this example, it is a mechanism that rotates horizontally around 2
It is a parallel link mechanism consisting of a set of parallelogram links.

The mechanism 9 has links 9a and 9b at its lower part when the member 8 is in a horizontal state.
A link 9f with a lever 9f protruding from the tip is connected to the link 9e
Then, connect the tip of the lever 9f and the tip of the link 9b.
A link 9h is attached 91 to the tip of a lever 9a protruding from the tip of the link 9a.
At the same time, a pair of parallelogram links is formed by connecting link 9j to link 9t between the image tips of links 9f and 9h. M5 is an electric motor that rotates the link 9a around the shaft 9c. Note that the tip link 9j of the mechanism 9 is configured as a holding member for the welding torch T.

Reference numeral 81 denotes a welding line tracing sensor supported at the tip of the holding member 9j, and in the embodiment, a horizontal joint 1
0a and protrudingly biased by a bullet (not shown),
This is a contact type sensor composed of a vertical surface tracing roller lO of the plate material W2 and a differential transformer TR attached to the holding member 9j to detect the protruding position of the roller 10.

Reference numeral 11 denotes a free roller for tracing the upper surface of the plate material W1, which is attached to the lower part of the holding member 9j (coaxially with the shaft 9).

Note that the position of the joint 10a of the roller 10 is such that at the reference protrusion position of the roller 10 at the preset reference output value of the sensor 81, the distance between the shafts 9c and 9e is equal to the distance between the shafts 9 and 10b, and the distance between the shafts 9e and 10b is equal.

The distance between the axes 9c and 10b is set to be equal to the distance between the axes 9c and 10b. The attachment position of the torch T to the holding member 9j is such that the position P of the welding point of the torch T coincides with the horizontal plane below the tip of the roller 10 and passing through the lower end of the roller 11 at the reference protruding position of the roller 1o. It is set as follows. The torch T is configured to horizontally rotate about the shaft 10b without struggling with the rotation of the link 9a, so that the angle of the torch T with respect to the welding line WL can be changed.

E5 is an encoder for detecting the angle of the torch T with respect to the welding line WL.

S2 is a plate w2 detector (for example, a limit switch) that is protruded from each side of the truck 1, four in total.

C is a device that controls the electric motors M1 to M5 and the welding power source ws, and is mainly a computer including a central processing unit CPU and a memory MEM.

And motors Ml-M5, drive circuits for these motors (
Drivers MD1 to MDs, encoders E1 to E5, sensor 81, detector S2, and power source ws are connected to control device C via path line B as shown in FIG.

The control device C includes a second means A2 for controlling the movement of the movable body 6 so that the output value of the sensor S1 is almost constant based on the output information of the sensor S1, and a welding line WL of the torch T.
The second means A2 is designed to control the rotation of the mechanism 9 so that the angle with respect to the welding line W is constant;
A fourth means is included for controlling the steering of all the wheels 2 so that the distance between L and the truck 1 is substantially constant.

The first means A includes means for calculating the difference between the output value from the sensor S1 and a preset reference value (step 5).
T2) is included. The second means A2 also includes means (step 5Ts) for calculating the direction of a straight line passing through both positions (the direction of the welding line WL) from the position information of the position PirPi+1 of each welding point before and at the present time for a certain period of time. , the torch angle with respect to the direction of the straight line (in the example, the torch angle with respect to the line perpendicular to the straight line on the plate W1 surface)
(step 5T6).

Furthermore, the eighth means A3 includes step S Ts, means (stenob s'rs) for calculating the position Pi+2 of the next virtual welding point that will be reached after a predetermined time on the straight line, and Pi+2 A certain distance L from the current position to the moving direction of the moving body 6 (left and right direction of the truck 1) and to the truck 1 side.
2 (Torch T at the preset reference position of the moving body 60
means (step 5T9) for calculating the next virtual position Oi+2 of the vertical axis 5a separated by the distance between the position of the welding point and the vertical axis 5a);
It includes means (step S Tl0) for calculating the distance t from i+1 and further dividing the distance t by a certain time t. Furthermore, the fourth means A4 includes the step STs, step STs, and step ST9.
and a means (step 5T12) for calculating the direction of a straight line passing through Oi+2 and O1+1, and further calculating the angle φ of the straight line with respect to the current steering direction of all wheels 2.

Further, the operation of this embodiment will be explained based on the flowcharts in FIGS. 9(0) and (b) and FIG. 1θ.

First, the operator places the cart 1 at the position shown by the solid line in FIG. At this time, the rotating body 5 is set at a rotation angle such that the direction of movement of the movable body '6 is perpendicular to the direction in which the cart 1 is desired to move (vertical direction in FIG. 4). Further, the roller IO is in contact with the vertical surface of the plate material W2. Furthermore, the roller 11 is brought into contact with the upper surface of the plate material wl, and its rotation is restrained by the gravity of the member 80 about the shaft 8a. For convenience of explanation, it is assumed that the mechanism 4 is steered at an angle in which all wheels 2 are directed upward in FIG.

Then, when the start switch of the control device C is turned on, the power source WS is turned on. On the other hand, with the axis 5a as the origin Oi and the steering direction of all wheels 2 as the Xi axis, positional information on the position Pi of the welding point is taken into the computer C (step 5T1). Moreover, the forward rotation output of the driver MDI is turned on, the electric motor M1 is driven to rotate in the forward direction, all the wheels 2 are rotated in the forward direction via the mechanism 8, and the bogie 1 is moved upward from the solid line position in FIG. 4 at a predetermined welding speed. At the same time as the vehicle moves forward, the encoder E1 starts counting the distance traveled.

Then, the computer C takes in the output of the sensor S1, calculates the difference from a predetermined reference value, converts the difference into the length of the moving body 6 in the moving direction (step 5T2), and further converts the converted value into a length for a certain period of time. Divide by t. Note that this constant time t is related to the welding speed, but in this example it is 0.1
seconds (welding speed 10/sec). If the division value is positive, the counterclockwise rotation output of driver MD4 is O.
N, the moving body 6 is moved protrusively by the electric motor M4 at the speed of the above-mentioned division value (absolute value). Conversely, if it is negative, the clockwise rotation output of the driver MD4 is turned ON, and the moving body 6 is moved at the speed of the above-mentioned division value (absolute value). (step 5T3)
).

Therefore, the position P of the welding point of the torch T always coincides with the welding line WL. Note that steps S T2 to ST5-Ta constitute the first means A1 for controlling the movement of the moving body 6 so that the output value of the sensor 81 is approximately constant based on the output information of the sensor S1. Become.

Then, after a certain period of time t has elapsed, the current position Pi+1 of the welding point is calculated from the position information of sPi and the output of the encoder E1+E2y E4, and the position information of Pi+1 is taken into the computer C (step 5T4).

Then, the current steering angle is calculated from the encoder E2a output, and the steering direction is Xi+, the 1st axis, and the vertical axis 5a is the origin O.
The coordinates are replaced with i+1, and the coordinates of the P 1 + P 1 + 1 position are transformed in the new coordinate system. Then, calculate the direction of the straight line passing through PI + P i + 1 (direction of welding line WL) (Step 5T5), further calculate the direction of the line perpendicular to the straight line on the plate W1 surface, and Step STa) calculates the torch angle θ with respect to the direction of the line, and further divides the torch angle θ by a certain time t. If the division value θ/l is positive, the clockwise rotation output of driver MDs is O
N, the torch T is rotated to the right by the electric motor M5 at the speed of the above-mentioned division value (absolute value). Conversely, if the speed is negative, the counterclockwise rotation output of the driver MD5 is turned ON, and the torch T is rotated to the right at the speed of the above-mentioned division value (absolute value). value) to the left (step 5T7
).

Therefore, even if the welding line WL is a curve, the angle of the -torch T with respect to the welding line WL is approximately constant.

Note that step ST1 and steps ST4 to ST7
The second means A2 is configured to control the rotation of the mechanism 9 so that the angle of the torch T with respect to the welding line WL is approximately constant.
It is configured as follows.

Then, the preset welding speed (10/sec) is multiplied by a certain time t (0,1 sec), and on the straight line passing through Pi and Pi+1, the multiplied value (distance L1, that is, in this embodiment) is measured from the Pi+1 position. Then, the position of the next virtual welding point Pi+2 that is separated by l■), that is, the position Pi+2 that will be reached after a certain period of time has passed, is calculated (step 5Ts). Furthermore, a certain distance L2 (that is, a reference position of the moving body 6 is set in advance) from the Pi+2 position to the left and right direction of the trolley l (the current moving direction of the moving body 6), and at the reference position of the moving body 6, the welding point is position P and vertical axis 5a
A virtual position Oi+2 of the next vertical movement 5a which is away from the cart 1 by a distance of Furthermore, the distance t between the current position O4+1 of the vertical axis 5a and the next virtual point position Oi+2 is calculated, and the distance t is divided by a certain time t (step 5T10). Then, output the divided value 1/l to the driver MDI (Step 5Til)
, the truck l is made to travel at a speed equal to the divided value.

Therefore, even if the welding line WL is a curve, the welding speed is always approximately constant. Note that steps ST1 + ST4~
S T5. ST8 to S'I'll constitute the eighth means A3 which is intended to control the speed of the truck 1 so that the welding speed is constant.

Then, the direction of the straight line passing through Oi+1 and Oi+2 is calculated, and the angle φ of that straight line with respect to the Xi+1 axis (that is, the angle of that straight line with respect to the current steering direction of all wheels 2)
(step 5T12), and further divides the angle φ by the time t. If the division value φ/l is positive, the counterclockwise rotation output of driver MD2 is turned ON, and all wheels 2
is steered to the left at the speed of the above-mentioned division value (absolute value), and conversely, if it is negative, the clockwise rotation output of driver MD2 is turned on, and all wheels 2 are steered to the right at the speed of the above-mentioned division value (absolute value). (Step 5T13) 0 Therefore, even if the welding line WL is an extremely uneven curve,
The torch T, mechanism 9, and truck 1 do not collide with the plate material W2. Note that steps ST+ + ST4 to STs+
S TB + S T91 S T12 to S T13 are set in advance so that the distance between the trolley l and the welding line WL is almost constant, and the amount of movement of the next moving body 6 with respect to the reference position is almost zero. , the fourth means A4 is configured to perform steering control on all wheels 2.

Thereafter, the position information of Pi+1 is replaced with the position information of Pi, and the same operation as last time is repeatedly performed.

As described above, the output value of sensor S1 is kept almost constant, the torch angle with respect to welding line WL is kept almost constant, and the welding speed is kept almost constant regardless of the direction of welding line WL. Furthermore, the speeds are controlled as described above so that the distance between the truck L and the welding line WLI is approximately constant, and in the end, the welding line WL1 is automatically welded from the bottom to the top in Fig. 4. That will happen.

Then, as shown by the two-dot chain line 1 in Fig. 4, the trolley l finally moves to the board W.
2, the output of the detector S2 turns ON. Then, the count value (traveling distance) obtained by the encoder El is temporarily stored in the memory MEM, and also
I is turned off, and the truck I is stopped. Then, the clockwise rotation output of the driver MD3 is turned on, the rotating body 5 is rotated to the right, and counting by the encoder E3 is started. Then, when the count reaches 1, that is, when the count reaches 1, the driver MD3 is turned off, the rotating body 5 is stopped, and the power source WS is also turned off. Therefore, at this point, welding is completed for the weld line WLI.

Further, the reverse rotation output of the driver MD is turned ON, and the truck I moves backward, and moreover, the output of the encoder E1 is started. The driver M
Dl is turned OFF and the trolley 1 is stopped.

Furthermore, the clockwise rotation output of driver MD3 is turned on again.
Therefore, the rotating body 6 is rotated to the right, and the encoder E
Counting by 3 is started. Then, when the count reaches 3, that is, when the torch T reaches the position indicated by the two-dot chain line φ' in FIG. 4 to the position indicated by the two-dot chain line T in FIG. will be stopped.

Furthermore, the left rotation output of the driver MD2 is turned on, and all wheels 2 are steered to the left, and the encoder E
Counting by 2 is started. Then, when the count reaches 4, that is, when all the wheels 2 are steered 90 degrees to the left and turn leftward in FIG. 5, the driver MD 2 is turned OFF 1, and the steering is stopped. Furthermore, the forward rotation output of the driver MD is turned on.
Therefore, the truck l travels to the left in FIG. When the truck 1 collides with the plate W2 as shown by the two-dot chain line l in FIG. 5, the output of the detector S2 is turned ON, the driver MD1 is turned OFF, and the truck 1 is stopped.

Furthermore, the clockwise rotation output of the driver MD2 is turned on, and all wheels 2 are steered to the right, and the encoder E2
The count starts. Then, when the count reaches 5, that is, when all the wheels 2 are steered 90 degrees to the right and are oriented toward one side in FIG. 6, the driver MD2 is turned OFF and the steering operation is stopped. Further, the forward rotation output of the driver MD1 is turned on, and the truck 1 moves forward. Then, the roller IO finally collides with the vertical surface of the plate W2, and the output of the sensor SL is released from the limit, and the release output signal causes the driver MDI to
is turned OFF, and the truck I is stopped at the position shown in FIG.

Further, the counterclockwise rotation output of the driver MD3 is turned on, the rotating body 5 is rotated to the left, and counting is started by the encoder E3. And the count amount is 6
In other words, the torch T is at the double-dashed line T in Fig.
When the driver MD3 reaches the T position, the driver MD3 changes to 0.
When the FF is activated, the rotating body 5 is stopped.

Furthermore, the clockwise rotation output of the driver MD2 is turned ON, and all wheels 2 are steered to the right, and the encoder E
Counting starts with 2. When the count reaches 7, that is, when all the wheels 2 are steered 90 degrees to the right and turn to the right in FIG. 6, the driver MD2 is turned off and the steering operation is stopped.

Then, the power supply WS is turned ON again, and the driver MD3
The clockwise rotation output is also turned ON, the rotating body 5 is rotated clockwise, and the encoder E3 starts siclanting. Then, when the count reaches eight, that is, when the torch T reaches the T position from the two-dot chain line T position in FIG. 6, the driver MD3 is turned off and the rotating body 5 is stopped. Therefore, the welding line WL2 between the two-dot chain line T position in FIG. 6 and the T position is automatically welded.

Then, the forward rotation output of the driver MD is turned ON, and a memo! Once stored in JMEM, the count amount described above (in Figure 4, the number of carts from the welding start position to the T position)
The encoder E is set as the initial value
The count by 1 is restarted, and the above-mentioned step S T
The actions after 2 are executed.

Therefore, the welding line WLa will be automatically welded to the right from the position of the two-dot chain line T in FIG.

Then, welding lines WL2tWL3 are automatically welded in the same manner as described above, and when the count by encoder E1 reaches 9, that is, when the trolley l has traveled until the torch T reaches the lower end position of welding line WL3 in Fig. 4, The power source WS is turned off, and the driver MD is also turned off, the truck 1 is stopped, and the automatic welding of the welding line WL is completed.

As is clear from the above description, each weld line WL.

- The vicinity of the intersection of WL3 is automatically welded based on the subroutine flowchart in Figure 1θ, and the output of sensor sl is In addition, the welding speed is adjusted so that the values are approximately constant, the torch angles relative to the welding line WL are approximately constant, and the welding speed is adjusted to the welding line WL.
Automatic welding is performed while controlling the respective speeds so that the distance between the truck I and the welding line WL is approximately constant regardless of the direction, and furthermore, so that the distance between the truck I and the welding line WL is approximately constant.

The above description is an example. For example, if the welding line WL is substantially straight, the rotating body 5 can be eliminated and the movable body 6 can be moved in the left-right direction with respect to the truck l.

It is also possible to omit the means A3. Also, method A.

r A2+ A4 may be used for position control instead of speed control.

In addition, the center of rotation of the torch T by the link mechanism 9 may be set to coincide with the tip position of the roller 10 at the reference protruding position of the roller 10 at the reference output value of the sensor S1. It may be a non-contact type sensor such as a sensor, an electromagnetic sensor, or a so-called arc sensor that uses the torch T itself as a tracing sensor.Furthermore, the mechanism 9 may eliminate the links 9b and 9h and have the shafts 9c, 9a, and It goes without saying that the technical scope of the present invention also includes the replacement of each structure with equivalents, such as interposing transmission means consisting of a boot and a timing belt between the shafts 9e and 9a, respectively.

As is clear from the above description, this invention is provided with only one sensor S1, but the control device controls (a) the amount of approach and distance of the torch T to the welding line WL (the amount of movement of the moving body 6); The torch angle, the speed of bogie 1 and the steering angle of all wheels 2 with respect to WL.

Alternatively, (b) the amount of approach and distance of the torch T from the welding line WL (the amount of movement of the moving body 6), the torch angle with respect to the welding line WL, and the steering angle of all wheels 2 can be controlled. That is, since even one sensor 81 can control a plurality of elements by the control device C, there is no need to attach a large number of sensors to the welding device as in the conventional case, and the structure can be made simple, lightweight, and compact. Further, since the mechanism 9 is designed so that its tip 9j rotates around a virtual point (axis 1Ob in the embodiment), even if the mechanism 9 is rotated to rotate the torch T, the mechanism 9 does not move around the workpiece. There is no joy in colliding with someone.

[Brief explanation of drawings]

Each of the figures shows an embodiment of the present invention, in which Figure 1 is a perspective view for explaining the whole, Figure 2 is a bottom view of the traveling trolley, and Figure 3 shows the tip of the vehicle rotating around an imaginary point. 4 to 7 are diagrams for explaining the operation, FIG. 8 is a block diagram of the control device, and FIG. 9 (a) and ←) and FIG. 10 are flow charts for explaining the operation. In the figure, Wl...work (horizontal plate material), W2...
...Work (vertical plate material), WL (WLI~WLa
)...Welding line, T Welding torch, P...Torch T
The position of the welding point, 1. Traveling truck, 2. Wheels, 4.
・Steering mechanism, 5... Rotating body, 5a... Vertical axis, 6.
... Moving body, 9... Mechanism whose tip part is to horizontally rotate around an imaginary point, 9j... Mechanism 9 tip part (
torch T holding member), lO... tracing roller %S1
...Welding line tracing sensor, C...Control device, S T
l...Means for calculating the difference between the output value from the sensor St and a preset reference value, S Ts...Calculating both positions from the position information of the positions P1+Pi+1 of each welding point a certain period of time ago and now. Means for calculating the direction of a straight line passing through, Si2・
...Means for calculating the torch angle with respect to the straight line direction of means ST5, S Ts...Means for calculating the position Pi+2 of the next virtual welding point, which will be reached after a certain period of time on the straight line of ST5. Means, S T9...Pi+
A certain distance L from position 2 to the left and right of trolley 1 and towards the trolley l side.
Means for calculating the next vertical axis 5a virtual position O1+2 separated by 2, STIO...O1+2 and the current vertical axis 5
Means for calculating the distance t from the position 01+1 of a and further dividing the distance t by a certain time t, S T12...Oi
+2. Means for calculating the direction of a straight line passing through Oi+1 and further calculating the angle φ of the straight line with respect to the current steering direction of all wheels 2, AI...The moving body 6 so that the output value of the sensor S1 is almost constant A2... A second means for controlling the rotation of the mechanism 9 so that the angle of the torch T with respect to the welding line WL is substantially constant, A3... The welding speed is substantially constant. Eighth means for controlling the speed of the truck l so that A4... welding line W
This is a fourth means for controlling the steering of all wheels 2 so that the distance between L and the truck is approximately constant. Applicant ShinMaywa Industries Co., Ltd. Agent Tadashi Bengami (and 1 other person)

Claims (8)

[Claims] (1) All wheels are connected to the steering mechanism and connected to the next traveling bogie.
A moving body supported by the traveling truck and movable in the left-right direction of the traveling truck; a mechanism supported vertically by the moving body and having a distal end horizontally rotated around an imaginary point; a welding torch holding member integrated at the tip;
A welding line tracing sensor supported by the holding member, and a control device configured to automatically weld the welding line of the workpiece based on the output of the sensor, the control device controlling the output value of the sensor based on the output information of the sensor. a first means for controlling the movement of the movable body so that the angle of the welding torch with respect to the welding line is approximately constant; a second means for controlling the rotation of the mechanism so that the angle of the welding torch with respect to the welding line is approximately constant; Eighth means for controlling the speed of the traveling truck so that the welding speed is approximately constant; and eighth means for controlling the steering of all the wheels so that the distance between the welding line and the traveling truck is approximately constant. A fillet profile welding device comprising four means. (2) The fillet profile welding apparatus according to claim 8flE1, wherein the weld line profile sensor is a contact type sensor. (3) The fillet profile welding apparatus according to claim 1, wherein the weld line profile sensor is a non-contact type sensor. (4) The fillet profile welding apparatus according to claim 1, wherein the first means includes means for calculating the difference between the output value of the weld line profile sensor and a preset reference value. . (5) The second means includes means for calculating the direction of a straight line (direction of the welding line) passing through both positions from the position information of each welding point a certain time ago and the current time, and calculating the torch angle with respect to the straight line direction. The fillet profile welding apparatus according to claim 1, further comprising calculating means. (6) The eighth means includes means for calculating the direction of a straight line passing through both positions from the position information of each welding point a certain time ago and the current time, and a direction of a straight line that is reached on the straight line and after the elapse of the certain time. a welding point of the welding torch at a preset reference position of the movable body; a distance between the next virtual position and the current position of the traveling cart, and a means for calculating a distance between the next virtual position and the current position of the traveling cart, and setting the distance to the fixed distance. 2. A fillet profile welding apparatus according to claim 1, further comprising means for dividing by time. (7) The fourth means includes means for calculating the direction of a straight line passing through both positions from the position information of each welding point a certain time ago and the present, and reaching the direction on the straight line and after the elapse of the certain time. a welding point of the welding torch at a preset reference position of the movable body; means for calculating the next virtual position of the traveling vehicle which is separated by a distance between the position of The fillet profile welding device according to claim 1, further comprising means for calculating an angle of the straight line with respect to the current steering direction of all the wheels. (8) A running bogie with all wheels connected to a steering mechanism, a moving body supported by this running bogie and movable in the left and right direction of the running bogie, and a vertically supported pivot on this moving body, the tip of which is virtual. A mechanism that horizontally rotates around a point, a holding member for the welding torch integrated at the tip of this mechanism, a welding line tracing sensor supported by this holding member, and a welding line on the workpiece based on the output of this sensor. a control device for automatically welding the movable body, and the control device includes a first means for controlling the movement of the movable body so that the output value of the sensor is approximately constant based on the output information of the sensor; Two means are used to control the rotation of the mechanism so that the angle of the welding torch with respect to the welding line is approximately constant; and two means are provided to steer all of the wheels so that the distance between the welding line and the traveling truck is approximately constant. and fourth means for controlling the fillet welding.