JPH0366991B2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention supports a moving body capable of at least left and right movement on a traveling carriage having a steering mechanism, and a welding torch and a profiling sensor are attached to the tip side of the moving body. This relates to profile welding equipment.

(Prior Art) When the above-mentioned profile welding device performs profile welding on a curved weld line, it not only performs lateral position control of the movable body and steering control of the steering mechanism, but also performs the welding process on the weld line. Good welding results cannot be obtained without controlling the torch angle. Therefore, conventionally, it is necessary to add a sensor for detecting the direction of the weld line in addition to the profile sensor.

(Problem to be Solved) However, it is not preferable to provide a large number of sensors in a profile welding device. In particular, the structure near the welding torch becomes complicated and is susceptible to spatter.

(Means for Solving the Problems) The present invention has been made in view of the above-mentioned circumstances, and includes a traveling bogie having a steering mechanism, and a movable vehicle that is supported by the traveling bogie and is movable in the left and right direction. a parallelogram link mechanism supported by the movable body, whose tip is a support member for a welding torch, and which is capable of rotating the welding torch around a vertical axis about the position of the welding point. a welding line tracing sensor supported on the support member; and a control device configured to control the position of the movable body to weld the welding line by tracing the welding line based on the output of the welding line tracing sensor, and the control device includes: Means for determining a multidimensional curve passing through three or more positions from each position information of the current welding point position and the past positions of at least two welding points based on the current position of the traveling truck; means for determining a tangent to the multidimensional curve at the current welding point position or the next virtual welding point position that will be reached after a certain period of time has elapsed on the multidimensional curve; means for determining the direction that provides the optimal angle;
and means for determining the current angle of the welding torch with respect to the direction, and rotating the parallelogram linkage by an amount corresponding to the angle to maintain the angle of the welding torch with respect to the welding line at an optimal angle. It is characterized by what one should do.

(Function) While controlling the position of the movable body in the left-right direction by the output of the profiling sensor, the position of the current welding point and the position of at least two past welding points are controlled based on the current position of the traveling truck. From the position information, a multidimensional curve that passes through these three or more points is determined, and further, a multidimensional curve passing through the positions of three or more points is obtained, and further the multidimensional curve is calculated at the current welding point position or the next virtual welding point position that will be reached after a certain period of time on the multidimensional curve. Determining a tangent to the multidimensional curve, further determining a direction in which the welding torch is at an optimal angle with respect to the tangent, and determining the current angle of the welding torch with respect to the direction;
The angle of the welding torch with respect to the welding line is corrected by the angle.

(Example) In this example, a movable body is mounted so as to be movable in the left and right directions on a traveling trolley that can steer all wheels simultaneously in the same direction and at the same angle, and a torch support member is vertically supported on this movable body. Although the present invention will be described as a traveling truck-type fillet welding device in which a fillet welding line tracing sensor is provided on the torch support member, it may also be a butt welding device. In addition, for example, a welding device may be used in which a torch support member is vertically supported on an arm of a rectangular coordinate robot that moves back and forth, and the present invention is not limited to this embodiment.

W ₁ and W ₂ are workpieces, respectively, where W ₁ is a horizontal workpiece and W ₂ is a vertical workpiece. Both works
W ₁ and W ₂ are mutually positioned and tack welded in advance as shown in FIG. WL(WL ₁ ,
WL ₂ ) is a weld line (horizontal fillet weld line) formed by both workpieces W ₁ and W ₂ and bent at 90 degrees.

Reference numeral 1 denotes a traveling trolley whose planar shape is approximately quadrilateral (approximately square in the embodiment), and a total of four wheels 2 are mounted thereon. All wheels 2 are configured to be driven in the same direction by an electric motor _M1 attached to the bottom of the truck 1 via a power transmission mechanism 3 consisting of a chain 3a, sprockets 3b, 3c, and bevel gears 3d, 3e. ing. Although _E1 is not shown in detail, it is an encoder for detecting the amount of wheel rotation connected to the wheel 2. S1 is a servo system including an electric motor _M1 and an encoder _E1 .

Reference numeral 4 denotes a steering mechanism, which is configured to be able to simultaneously steer all wheels 2 in the same direction and at the same angle via a chain 4a and sprockets _4b , 4c by an electric motor M2 attached to the bottom of the truck 1.
E ₂ is a steering angle detection encoder of the mechanism 4, although its details are not shown. S2 is a servo system including electric motor _M2 and encoder _E2 .

5 is vertically supported 5a at the upper center of the trolley 1,
It is a rotating body rotated by electric motor _M3 . _E3 is
Although not shown in detail, it is an encoder for detecting the rotation angle of the rotating body 5. S3 is a servo system including electric motor _M3 and encoder _E3 . 5b is
This is a handle fixed to the upper part of the rotating body 5.

6 is a movable body supported by the rotating body 5 and movable in the horizontal direction by an electric motor _M4 . _E4 is an encoder for detecting the position of the moving body 6. S4 is
This is a servo system including electric motor _M4 and encoder _E4 .

7 is a tilting member supported by the movable body 6 and tiltable up and down by an electric motor _M5 . _E5 is an encoder for detecting the tilt angle of the member 7. S5 is a servo system including electric motor _M5 and encoder _E5 .

Reference numeral 8 denotes a welding torch support member which is vertically supported by the member 7 and rotated approximately horizontally about a shaft 8a via a known parallelogram link mechanism (not shown) by an electric motor _M6 . _E6 is an encoder for detecting the rotation angle of the member 8. S6 is an electric motor
It is a servo system including M ₆ and encoder E ₆ .

SH is supported by the member 8 and is a left-right direction tracing sensor for the weld line WL (contact type in the embodiment, but a non-contact type may also be used), and includes a contactor 9 biased to project by a spring (not shown), and a differential transformer _TR1 connected to the contactor 9. Furthermore, the sensor
SH is set such that the shaft 8a passes through the tip of the contact 9 at the protruding position of the contact 9 at a preset reference output value. Furthermore, the protrusion of the contactor 9 is limited by a stopper (not shown).

SV is supported by the member 7 and is a vertical tracing sensor for the weld line WL (contact type in the embodiment, but a non-contact type may be used), and includes a contactor 10 protrudingly biased by a spring (not shown), and this sensor. and a differential transformer TR ₂ connected to the contactor 10. Note that the sensor SV is set so that the member 7 is in a horizontal position at the protruding position of the contactor 10 at a preset reference output value.

T is a welding torch attached to the member 8.
The mounting position of the torch T is such that the welding point P of the torch T is below the tip of the contact 9 and above the tip of the contact 10 at the protruding position of the contacts 9 and 10 at the reference output values of the sensors SH and SV. It is set to be located on the horizontal plane that passes through it.

11 is a conduit cable including a signal cable, a power cable, a power supply cable to the torch T, and the like.

There are two SWs on each side wall of the trolley 1 (SW ₁
and SW ₂ ), a total of eight vertical workpiece W ₂ detection sensors (limit switches in the embodiment) are installed protrudingly.

C is a control device mainly composed of a computer including a central processing unit CPU and a memory MEM. The control device C includes each servo system S1 to S6 and an operation panel.
RB, welding power source WS, transformers TR ₁ , TR ₂ , switches SW ₁ , SW ₂ are connected via bus line BL.

Note that the control device C stores the current welding point position Pi+1, the past two welding point positions (in this example, the welding point position Pi a certain time t before the Pi+1 point, and further a certain time t from Pi). In the example of the previous welding point position Pi-1), from the position information of a total of three points, those three positions Pi-
1, Pi, and Pi+1 (in the example, it is a parabola, but other shapes such as a circle, an ellipse, or a hyperbola may be used) (step ST ₁₁ described later);
Tangent direction of curve R at current welding point position Pi+1 or future welding point position Pi+2 on curve R
H ₁ (in the example, the tangential direction passing through the Pi+1 position) (step ST ₁₂ described later), and the direction _{H 2} in which the torch T is at an optimal angle with respect to the tangential direction H 1
(Step ST ₁₃ to be described later), means to determine the current angle θ of the torch T with respect to the direction H ₂ (Step ST ₁₄ to be described later), and the link mechanism 8 is rotated by an amount corresponding to this angle θ. The angle of the torch T with respect to the welding line WL is maintained at an optimum angle (steps described later).
ST ₁₅ , ST ₁₆ ).

Note that the curve R may be a third-order or higher-order curve that passes through four or more current and past welding points.

Further, the operation of this embodiment will be explained based on the flowchart of FIGS. 6A and 6B with reference to FIGS. 4 and 5.

First, the operator turns on a power switch and a home positioning switch (not shown) on the operation panel RB.

At this time, the steering angle of the wheels 2 is such that all the wheels 2 are in the front-rear direction (the X direction shown in FIG. (Y _direction shown in _FIG . The origin of the member 8 is determined at a position where the value matches a preset reference output value, and furthermore at a position where the torch angle with respect to the X direction is optimal.

Then, the operator grasps the handle 5b, lifts the trolley 1, and moves the trolley 1 to the workpiece as shown in FIG.
Place it on W ₁ . Note that this placement position is the welding line.
A location near the starting end of WL ₁ (lower right end in Figure 1) is preferable.

At this time, the sensor _SH ,
The contacts 9 and 10 of the SV are connected to the workpieces W _{1 and 10} , respectively.
Determine the starting position so that it touches W ₂ .

Then, when a start switch (not shown) on the operation panel RB is turned on, (a) a command is output to turn on the welding power source WS; (Step ST ₁ ) (a) Also, the positional information of the welding point Pi is taken into the computer C, with the center position of the shaft 5a as the origin Oi and the steering direction as the Xi axis. (step
ST ₂ ) (c) Furthermore, a command is output to the electric motor M ₁ to move the cart 1 forward at the initially set welding speed (upward leftward in FIG. 1 and upward in FIG. 5). (Step ST ₃ ) (d) Moreover, the horizontal direction tracing control of the movable body 6 by the sensor SH and the tracing control of the tilting member 7 by the sensor SV are also started. (Step ST ₄ ) In other words, the CPU compares the output value from transformer TR ₁ with the reference value, and at a speed corresponding to the difference,
The moving body 6 moves the workpiece so that the difference becomes zero.
Remotely or close to W ₂ , the horizontal position of the torch T with respect to the welding line WL ₁ is controlled, and the output value from the transformer TR ₂ and the reference value are controlled.
The comparison is made by the CPU, and the member 7 is moved away from or close to the work W ₁ at a speed corresponding to the difference, and the welding line of the torch T is moved so that the difference becomes zero.
The vertical position relative to WL ₁ is controlled.

(e) Furthermore, whether or not a signal is output from at least one of the switches SW ₁ and SW ₂ on the front side of the truck 1, that is, the truck 1 collides with the workpiece W ₂ forming the welding line WL ₂ and the switch SW ₁ is activated. Whether it turned on or not, whether switch SW ₂ turned on or not,
is determined. (Steps ST ₅ and ST ₆ ) (f) If there is no signal output from either switch SW ₁ or SW ₂ , a certain period of time t (e.g.
0.1 seconds) has elapsed. (Step _ST7 ) As a result of this determination, if the time t has not elapsed, the process returns to step _ST5 .

(g) When time t has elapsed, the current welding point position Pi+1 is calculated from the position information of Pi and the output values of encoders E ₁ , E ₂ , and E ₄ , and that Pi
+1 position information is taken into computer C. (Step ST ₈ ) (h) Furthermore, calculate the current steering angle from the encoder E ₂ output value, set the steering direction as the Xi + 1 axis,
The coordinates are replaced with coordinates in which the current center position of the vertical axis 5a is the origin Oi+1. (Step ST ₉ ) (e) In the replaced new coordinate system,
The coordinates of PiPi+1 position are transformed. (step
_ST10 ) (j) Furthermore, a quadratic curve R (parabola in the embodiment) passing through the Pi-1, Pi, and Pi+1 positions is determined.
(Step ST ₁₁ ) The curve R is obtained with Oi+1 as the origin, the Xi+1 direction, and the yi+1 direction perpendicular thereto as coordinate axes.

(S) Find the tangent H ₁ (or normal line) of the curve R passing through the Pi+1 position. (Step _ST12 ) (C) Find the direction _H2 of the torch T that is the optimal angle with respect to the tangent _H1 on the _first surface of the workpiece W. (Step _ST13 ) (S) Calculate the current torch T angle θ with respect to the _H2 direction. (Step _ST14 ) (Se) Furthermore, the torch angle θ is divided by the time t. (Step _ST15 ) (S) Then, a command is output to the electric motor _M6 to rotate the torch T around the shaft 8a at a speed equal to the divided value. (Step ST ₁₆ ) As a result of this (S), the torch T is at the welding line WL ₁
The angle is always controlled to the optimum angle.

Note that the steps ST ₁₁ and ST ₁₂ described above constitute a means PR ₁ for determining the direction of the weld line WL.

(T) Furthermore, multiply the welding speed by the time t to obtain the future welding point position (position of the next virtual welding point) Pi+2 on the curve R that is separated by the multiplication value (distance L ₁ ) from the Pi+1 position. calculate.
(Step ST ₁₇ ) The Pi+2 position is the intersection of the curve R and a circle with radius L ₁ centered at the Pi+1 position.
The positions may be substantially separated by a distance _L1 on the curve R.

(H) Furthermore, a certain distance L ₂ from the Pi+2 position to the left and right direction of the cart 1 and to the cart 1 side (distance between the welding point position of the torch T and the center position of the vertical axis 5a at the preset reference position of the moving body 6) The position Oi+2 of the virtual point of the next vertical axis 5a which is separated by the distance Oi+2 is calculated. (Step ST ₁₈ ) (2) Furthermore, the distance l between Oi+1 and Oi+2 is calculated, and the distance l is further divided by the time t. (Step ST ₁₉ ) (Te) A command is output to the electric motor _M1 to make the bogie 1 run at the speed equal to the division value of (T) above.
(Step _ST20 ) As a result of this (TE), the rotational speed of the wheel 2 is controlled so that the welding speed remains constant even if the welding line WL is curved.

(g) Next, find the direction of the straight line _H3 passing through Oi+1 and Oi+2, and calculate the angle φ of the straight line _H3 with respect to the Xi+1 axis. (Step ST ₂₁ ) (Na) Divide the angle φ by the time t. (step
ST ₂₂ ) (d) A command is output to the electric motor M ₂ to steer all wheels 2 at the speed of the divided value. (Step _ST23 ) As a result of (d), the wheels 2 are steered and controlled so that the distance between the truck 1 and the welding line _WL1 is approximately constant.

(nu) Then, Pi's position information is transferred to Pi-1, and Pi's location information is transferred to Pi-1.
The position information of +1 is respectively replaced with Pi.
(Step ST ₂₄ ) After that, the process returns to step ST ₅ , and the same steps as the previous time are repeated, and in the end, welding line WL ₁ is traced and welded.

(N) By the way, if signals are output from switches SW ₁ and SW ₂ in steps ST ₅ and ST ₆ , the front side of truck 1 will be aligned with the weld line as shown in Fig. 5.
Since the collision occurred with workpiece W ₂ that forms WL ₂ , the electric motor is activated to stop truck 1.
A stop command is output to _M1 . (Step ST ₂₅ ) (n) Moreover, a command is also output to the electric motor _M3 to rotate the rotating body 5 to the right. (Step _ST26 ) (c) Simultaneously with the clockwise rotation command being output, counting by the encoder _E3 is started. (Step _ST27 ) (H) It is determined whether the count value has reached the K value. (Step ST ₂₈ ) That is, the rotating body 5 rotates to the right by a certain angle α, and the torch T is positioned at the _two- dot chain line T' in _FIG . It is determined whether or not the location (matching the location) has been reached.

(F) When the count reaches the K value, a stop command is output to the electric motor _M3 to stop the rotating body 5. (Step ST ₂₉ ) (f) Moreover, a command is output to turn off the power supply WS. (Step ST ₃₀ ) Therefore, by following steps (N) to (F) above, weld line WL
Profile welding will be performed at the end of weld line WL ₁ near the bending point.

The above description is an example, for example, the welding line
If there is no need to weld the area near the WL bending point, the rotating body 5 may be omitted. Also, if the workpiece W ₁ is accurately horizontal, the tilting member 7 and the sensor
SV may be abolished. Furthermore, the curve R may be a circle, an ellipse, or a hyperbola. Furthermore, the tangent H ₁
may be a tangent to the curve R passing through the point Pi+2.
It goes without saying that the technical scope of the present invention also includes the replacement of each component with equivalents.

(Effect) As mentioned above, this invention has a profile sensor SH.
While controlling the position of the movable body 6 in the left-right direction by the output of Tangent line H ₁ of the multidimensional curve R at the position of the next virtual welding point that will be reached after a certain period of time on the multidimensional curve R
This tangent line _H1 is regarded as the direction of the welding line WL, and the torch T is angularly controlled so that it is at the optimum angle. There is no need to separately provide a sensor for detection, which simplifies the structure. It also reduces the burden of having to consider the effects of spatter.

[Brief explanation of drawings]

The drawings all show one embodiment of the pattern welding device of the present invention; Fig. 1 is an overall perspective view, Fig. 2 is a bottom view of the traveling truck, Fig. 3 is a block diagram of the control device, and Figs. 4 and 5 are Figure 6 A and B are flowcharts for explaining the operation. In the figure, W ₁ ... horizontal workpiece, W ₂ ... vertical workpiece, WL (WL ₁ , WL ₂ ) ... welding line, 6 ... moving object,
8... Welding torch support member, T... Welding torch,
SH...Welding line tracing sensor, C...Control device, t...
Fixed time, Pi+2...Future welding point position, Pi+1
...Current welding point position, Pi...Welding point position a time t before the current position, Pi-1...Welding point position a time t before the Pi position, R...Multidimensional curve (quadratic curve in the example) , ST ₁₁ ...Means for determining the multidimensional curve R, ST ₁₂ ...Pi
Means for determining the tangent H ₁ or normal direction of the multidimensional curve R passing through the +1 position, ST ₁₃ ... Means for determining the direction H ₂ of the torch T that is the optimal angle with respect to the tangent H ₁ or the normal direction, ST ₁₄ ... Means for calculating the current angle θ of the torch T with respect to the direction H ₂ of the optimal angle, ST ₁₅
. . . means for dividing the angle θ by time t; ST ₁₆ . . . means for instructing the support member 8 to rotate by the division value of step ST ₁₅ ; PR ₁ . . . means for determining the direction of the welding line WL.

Claims (1)

[Claims] 1. A traveling truck having a steering mechanism, a moving body supported by the traveling truck and movable in the left-right direction of the traveling truck, and a moving body supported by the moving body, the tip of which is a support member for a welding torch. , and a parallelogram link mechanism capable of rotating the welding torch around a vertical axis around the position of the welding point, a weld line tracing sensor supported on the support member, and an output of the welding line tracing sensor. a control device configured to control the position of a movable body to follow a welding line and weld; Means for determining a multidimensional curve passing through three or more positions from each position information of the welding point position, and a means for calculating a multidimensional curve that passes through three or more positions from the position information of the welding point position, and a means for calculating the next welding point position that will be reached after a certain period of time has passed on the current welding point position or the multidimensional curve. means for determining a tangent to the polydimensional curve at the position of a virtual welding point; means for determining a direction in which the welding torch is at an optimal angle with respect to the tangent; and means for determining the current angle of the welding torch with respect to the direction. A profile welding device comprising: rotating the parallelogram link mechanism by an amount corresponding to the angle to maintain an angle of the welding torch with respect to the welding line at an optimum angle.