JPH0366992B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention supports a moving body capable of at least left and right movement on a traveling truck having a steering mechanism, and a welding torch and a profiling sensor are attached to the tip of the moving body. This relates to a tracing welding device equipped with a.

(Prior Art) Various profile welding devices as described above have been proposed. For example, there is a system in which the steering is controlled by changing the steering angle according to the output of the profiling sensor, and the traveling truck is made to travel along the welding line while welding the welding line. By the way, the steering angle is proportional to the output of the sensor, and the steering speed is not controlled. Therefore, even if the traveling speed of the traveling truck is constant, the welding speed may vary greatly, which affects the welding result.

(Problems to be Solved) This invention has been made in view of the above-mentioned circumstances, and in performing the steering control based on the output from the sensor, the steering speed is also controlled.
It is an object of the present invention to provide a tracing welding device that prevents large changes in welding speed.

(Means for Solving the Problems) The present invention includes a traveling truck having a steering mechanism, a moving body supported by the traveling truck and movable in the left and right direction of the traveling truck, and a vehicle provided at the tip of the moving body. A welding torch holding member, a welding line tracing sensor supported by the holding member, and a control device configured to control the position of the movable body based on the output of the sensor to weld the welding line. The device includes means for determining a quadratic curve passing through the three positions from each position information of the current welding point position and the past two welding point positions based on the current position of the traveling trolley; Means for calculating the position of the next virtual welding point that will be reached after a certain period of time or after traveling a certain distance on the curve, and a straight line that passes through the position of this next virtual welding point and the current position of the welding point. It is characterized by comprising means for determining the direction and further calculating an angle of the straight line with respect to the current steering direction, and controlling the steering mechanism at a speed obtained by dividing this angle by the certain time. It is something.

(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 positions of two past welding points are calculated based on the current position of the traveling trolley. These 3 from 3 points
Find a quadratic curve that passes through the point, and then calculate a straight line that connects the current welding point and the position of the next virtual welding point that will be reached after a certain amount of time or a certain distance has passed on this quadratic curve. The angle with respect to the current steering direction is determined, and furthermore, the steering mechanism is controlled at a speed obtained by dividing this angle by the predetermined time.

(Example) W ₁ and W ₂ are workpieces, 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 supported by member 7 and is designed to be rotated approximately horizontally about an axis 8a by an electric motor _M6 via a known parallelogram link mechanism (not shown). _E6 is an encoder for detecting the rotation angle of the member 8. S6 is electric motor _M6
and a servo system including encoder _E6 .

SH is supported by the member 8, and is a horizontal direction tracing sensor (contact type in the embodiment) for the welding line WL;
Contactor 9 urged to protrude by a spring (not shown)
and a differential transformer TR ₁ connected to this contactor 9.
including. Note that the sensor SH is set so 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 member 7 and is a vertical tracing sensor (contact type in the embodiment) for welding line WL;
Contactor 10 urged to protrude by a spring (not shown)
and a differential transformer connected to this contactor 10.
Including TR ₂ . 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 contains (1) the current welding point position P _i+1 , the past two welding point positions (in the example, the welding point position Pi a certain time t before this, and also Pi From the position information of a total of three points, including the position P _i-1 ) of the welding point a certain time t earlier, a quadratic curve R (in the example, a parabola) passing through those three positions P _i-1 , Pi, P _i+1 ) (step ST ₁₆ described later), and the position P of the next virtual welding point that will be reached on the curve R after a certain time t or after traveling a certain distance (in the example, after time t has elapsed). A means for calculating _i+2 (step ST ₁₇ to be described later) and a fixed distance from the P _i+2 position in the left-right direction and towards the trolley 1 side (the position of the welding point of the torch T at the preset reference position of the moving body 6). Means for calculating the next virtual position _O
ST ₁₈ ), O _i+2 position and current position of trolley 1 O _i+1
, and further includes a means (step ST ₂₁ to be described later) for calculating the angle φ of the straight line H ₃ with respect to the current steering direction of all wheels 2 (X _i+1 axis) _. , steering control means PR ₁
It is included.

(2) Also, the distance l between the O _i+1 position and O _i+2 position
and further divides the distance l by the time t (step ST ₁₉ described later),
Welding speed control means PR ₂ are included.

(3) Furthermore, means for determining whether at least one of the two switches SW ₁ and SW ₂ on the front side in the traveling direction of the truck 1 has output a signal (steps ST ₅ and ST ₆ to be described later); When the signal is output in this judgment, a means for outputting a stop command to the trolley 1 (step ST ₂₅ to be described later), after the trolley 1 has stopped, commands the rotating body 5 to rotate by a certain angle α to the right. Output method (steps described later)
ST ₂₆ ), means for outputting a stop command to the rotating body 5 after the rotation by angle α of the rotating body 5 (step ST ₂₉ described later), and means for outputting an OFF command to the welding power source WS (step ST described later) ₃₀ ) and a welding control means PR ₃ for the end portion of the bending point of the welding line WL.

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 (upwards to the left in FIG. 1, upwards 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 output value from the transformer TR ₁ and the reference value are compared by the CPU, and the moving body 6 is moved remotely or from the workpiece W ₂ at a speed corresponding to the difference, so that the difference becomes zero. As they approach, the horizontal position of the torch T with respect to the welding line WL ₁ is controlled, and the CPU compares the output value from the transformer TR ₂ with the reference value, and the difference becomes zero at a speed corresponding to the difference. As such, the member 7 moves away from or approaches the workpiece _W1 , and the vertical position of the torch T with respect to the welding line _WL1 is controlled.

(E) Furthermore, switches SW ₁ and SW ₂ on the front side of trolley 1
In other words _, whether _or not a signal is output from at least one _of the
It is determined whether the switch SW ₂ is turned ON or not. (step
ST ₅ and ST ₆ ) (F) If there is no signal output from either switch SW ₁ or SW ₂ , it is determined whether a certain period of time t (for example, 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 P _i+1 is calculated from the position information of Pi and the output values of encoders E ₁ , E ₂ , and E ₄ , _and Position information is taken into computer C. (Step ST ₈ ).

(h) Furthermore, calculate the current steering angle from the output value of encoder E ₂ , set the steering direction as the X _i+1 axis, and replace it with coordinates where the current center position of the vertical axis 5a is the origin O _i+1. be done. (Step ST ₉ ) (i) In the replaced new coordinate system, the positions Pi and P _i+1 are subjected to coordinate transformation. (Step ST ₁₀ ) (j) Furthermore, the direction of the straight line _H1 passing through the positions Pi and P _i+1 is determined. (Step _ST11 ) (S) Find the direction _H2 of the torch T that is the optimal angle with respect to the straight line _H1 on _one surface of the workpiece W. (Step ST ₁₂ ) (C) Current torch T for that _H2 direction
Calculate the angle θ. (Step _ST13 ) (S) Furthermore, the torch angle θ is divided by the time t. (Step _ST14 ) (Se) 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 ₁₅ ) As a result of this (C), the torch T is at the welding line.
The angle is always controlled to be optimal for WL ₁ .

(S) Next, find a quadratic curve R passing through three points: the past two welding point positions P _i-1 and Pi and the current welding point position P _i+1 . (Step ST ₁₆ ) The curve R is centered at the origin O _{i+ 1}
direction and the y _i+1 direction perpendicular to this direction as the coordinate axes.

(T) Furthermore, multiply the welding speed and time t,
On the curve R, a position P _i+2 of the next virtual welding point that is separated from the P _i+ 1 position by the multiplication value (distance L ₁ ) is calculated. (Step ST ₁₇ ) The P _i+2 position is the intersection of the curve R and a circle with a radius L ₁ centered at the P _i+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 P _i+2 position to the left and right direction of the cart 1 and to the cart 1 side (the position of the welding point of the torch T at the preset reference position of the moving body 6 and the center position of the vertical axis 5a) The position of the virtual point of the next vertical axis 5a separated by a distance of
Calculate O _i+2 . (Step ST ₁₈ ) (T) Furthermore, the distance l between O _i+1 and O _i+2 is calculated, and the distance l is further divided by the time t.
(Step ST ₁₉ ) (Te) Carriage 1 moves at the speed of the division value of (T) above.
A command is output to electric motor _M1 to make it run. (Step ST ₂₀ ) As a result of (TE), the wheel 2 is adjusted so that the welding speed remains constant even if the welding line WL is curved.
The rotation speed of is controlled.

(g) Next, find the direction of the straight line H ₃ passing through O _i+1 and O _i+2 , and calculate the angle φ of the straight line H ₃ with respect to the X _i+1 axis. (Step ST ₂₁ ) (Na) Divide the angle φ by the time t. (Step _ST22 ) (d) A command is output to the electric motor _M2 to steer all wheels 2 at the speed of the divided value. (Step ST ₂₃ ) As a result of (d), trolley 1 and welding line WL ₁
The wheels 2 will be steered and controlled so that the distance from the vehicle to the vehicle is approximately constant.

(J) Then, the position information of Pi is replaced with P _i-1 , and the position information of P _i+1 is replaced with Pi. (Step ST ₂₄ ) After that, the process returns to step ST ₅ , and the same steps as before 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 Figure 5.
Since it has collided with the work W ₂ forming WL ₂ , a stop command is output to the electric motor M ₁ to stop the cart 1. (step
( _ST25 ) (n) Furthermore, 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 output, counting by the encoder _E3 is started. (Step _ST27 ) (H) It is determined whether the count amount 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 moves to the position shown by the two-dot chain line T _' in FIG _.
It is determined whether the position coincides with the refraction point).

(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,
Welding line WL ₁ near the bending point of welding line WL
Profile welding of the end portion will be performed.

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, if the welding line WL is substantially straight, the support member 8 may be fixed to the tip of the movable body 6. Furthermore, the curve R may be a circle, a hyperbola, or an ellipse. 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 moving body 6 using the output of
P _i+1 and the past two points Pi, P _i-1 including this point P _i+1
Find the next virtual welding point P _i+2 that will be reached after a certain time t on the quadratic curve R passing through
Calculate the angle difference Φ between the current steering direction and the straight line passing through P _i+1 and P _i+2 , divide this angle Φ by time t, and use this divided value (speed) to perform steering control. Therefore, since the steering speed is also controlled, the amount of change in steering suddenly becomes large compared to the conventional system where the steering angle is simply changed according to the output of the tracking sensor. Therefore, there is almost no change in welding speed. In other words, the welding result is good.

[Brief explanation of drawings]

The drawings all show an embodiment of the pattern welding device of the present invention, with Fig. 1 being an overall perspective view, Fig. 2 being a bottom view of the traveling truck, Fig. 3 being a block diagram of the control device, and Figs. 4 and 5 showing the operation. The explanatory diagram and FIGS. 6A and 6B are flowcharts. In the figure, W ₁ ... horizontal workpiece, W ₂ ... vertical workpiece, WL (WL ₁ , WL ₂ ) ... welding line, 1 ... traveling trolley,
2... Wheels, 4... Steering mechanism, 6... Moving body, 8... Holding member, T... Welding torch, SH... Welding line tracing sensor, C... Control device, t... Fixed time, P _i+1 ... Current Position of the welding point, Pi...Position of the welding point time t before the present, P _i-1 ...Position of the welding point 2t before the present, R...Quadratic curve, P _i+2 ...Time t after the present position of the next virtual welding point, L ₂ ... constant distance, O _i+1 ... current position of truck 1, O _i+2 ... next virtual position of truck 1 after time t from now, H ₃ ... O _{i+ 1} and O _i+2 , X _i+1 ... Current steering direction of wheel 2, φ... Straight line
Angle of H ₃ with respect to the X _i+1 axis direction, ST ₁₆ ...Means for determining the quadratic curve R, ST ₁₇ ...Position of the next virtual welding point
ST ₁₈ . . . means for calculating the next virtual position O _{i + 2 of} the bogie 1; ST ₂₁ . . . means for calculating the angle φ; PR _{1 .} . . steering control means.

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, a welding torch holding member provided at the tip of the moving body, and a holding member for the welding torch provided at the tip of the moving body, It is equipped with a welding line tracing sensor supported on a member, and a control device configured to control the position of the movable body based on the output of this sensor to weld the welding line. Means for determining a quadratic curve passing through these three positions from each position information of the current welding point position and the past two welding point positions based on Means for calculating the position of the next virtual welding point that will be reached after traveling, determining the direction of a straight line passing through the position of this next virtual welding point and the current position of the welding point, and further calculating the current direction of the straight line. A profile welding device comprising means for calculating an angle with respect to a steering direction, and the steering mechanism is controlled to steer at a speed obtained by dividing this angle by the certain time.