JPS5820706B2 - Fillet weld point detection method in automatic welding robot - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting a workpiece groove, particularly a corner weld point, in a so-called automatic welding robot.

A so-called automatic welding robot that controls the relative positions of a workpiece and a torch based on commands from a control device, moves the relative position of the torch along the welding line of the workpiece, and automatically performs welding is well known. .

In this case, due to errors in each workpiece, the position taught for the first workpiece is not necessarily accurate for all subsequent workpieces, and the shape and dimensions of the groove vary depending on the workpiece. Accurate sensing of welding points was not possible.

Therefore, in this invention, in particular, the corner welding point of a workpiece made by abutting two members extending in two axial directions orthogonal to each other is accurately detected even if there is some dimensional error. The purpose of the present invention is to provide a method for detecting fillet welding points in an automatic welding robot that solves the problems.

Before explaining the present invention in detail, an example of an automatic welding robot in which a torch also serves as a sensor, which is the background of the present invention, will be explained.

In FIG. 1, the automatic welding robot has a robot main body 10
0, a power supply 200 including one for welding and one for detection, a welding control device 300 and a control box (including a computer) 400, and a remote control spring A300.

Main body 100 includes a base 101 .

The base 101 is provided with a pair of support columns 102 and 103 spaced apart from each other at both ends of the base 101 in the width direction, and the support columns 102 and 103 cooperate to support the rotating frame 104.

The rotating frame 104 includes a central member 104c and side frames 104a and 104b extending in parallel from both ends of the central member 104c.

104b is rotatably supported on the pillars 102 and 103, respectively.

The pillar 103 is further provided with a forward/reverse motor 105 equipped with a speed reducer and a brake on its back, and the rotation frame 104 is rotated around the horizontal axis H (in the direction of the arrow Y) by driving the motor 105. It's like moving it.

Further, a forward/reverse motor 107 with a speed reducer and a brake is provided on the back surface of the central member 104c at approximately the center thereof, and the motor 107 is driven to rotate the axis Kt (arrow θ) perpendicular to the horizontal axis H. The workpiece mount 106 is pivotally supported so as to be rotatable in the direction (direction).

Reference numerals 108 and 109 denote a pair of pillars erected on the base 101 at left and right distances behind the pillars 102 and 103, and a beam 110 is installed between the upper ends of the pillars 10B and 109.

A left-right moving body 111 straddles the beam 110 and is movable along the beam 110 in the left-right direction (direction of arrow X) parallel to the horizontal axis H.

A front-back moving body 112 movable in the front-rear direction (direction of arrow Y) is fitted to the upper part of the left-right moving body 111, and a front-back moving body 112 movable in the vertical direction (direction of arrow Z) is fitted to the front end of the front-back moving body 112. A vertical moving body 113 is fitted therein.

Furthermore, a base end of an elongated support member 1140 whose tip extends forward is fixed to the lower end of the vertically movable body 113, and a torch is attached to the tip of the support member 114, which is rotatable about the vertical axis Mt (in the direction of the arrow φ). A tool 115 is provided.

A torch 116 is fixedly attached to the tip of the torch fixture 115 so that the tip welding point WP is placed on the vertical axis M.

Furthermore, although details are not shown in the drawings, the torch fixture 115 is configured to control the turning angle φ relative to the vertical axis Mt by a power source built into the support member 114.

A voltage is applied between the torch 116 and the workpiece fixture 106 by a power source 200, and the power means for each of the above-mentioned parts, that is, the motors 105, 10? and left and right moving body 111,
Back and forth moving body 112. The forward/reverse movement, movement, and rotation of the vertical moving body 113 and the torch fixture 115, as well as the heating source time pressure and current, etc., are automatically controlled by the control box 400 and welding control device 300 according to a predetermined program. .

As a result, the relative positions of the workpiece W and the torch 116 are controlled so that the point of action at the tip of the torch 116, that is, the welding point, is along the welding line of the workpiece W, and automatic welding can be performed in an orientation with the best welding conditions. do.

For the purpose of creating additional programs or for manual operation, a remote control spring/l 500 is provided.

Thus, the robot main body 100 is
,M.

It has degrees of freedom about six axes, K and H.

Then, such a main body 100, devices 200, 300,
For more detailed configuration, operation, and operation of 400°500, see, for example, Japanese Unexamined Patent Application Publication No. 1986-53 filed by the same applicant.
12749, detailed description thereof will be omitted.

Further, as shown in FIG. 2, the power supply device 200 is provided with a consumable electrode supply means 201 for supplying a consumable electrode 209 to the torch 116, and the consumable electrode supply means 201 includes:
Further, a force device 202 is provided to give the consumable electrode 209 a bending direction.

In this embodiment, the force device 202 has a loop-shaped tube for guiding the consumable electrode 209 so that the tip of the consumable electrode 209 is always bent to a certain degree.

However, in addition to this embodiment, the force device 202 may be of a type that is clamped by guide rollers to force the consumable electrode into a straight line.

Consumable electrode 20 sent out from consumable electrode supply means 201
9, a predetermined voltage is applied by a voltage applying means 203, and the voltage applying means 203 selectively applies a voltage to either the welding power source 205 or the discharge high voltage power source 206 as the detection power source via the changeover switch 204. It is possible to connect to.

As is well known, the welding power source 205 has a large current and low voltage, and the discharge high voltage power source 206 has a small current and high voltage (approximately 1000 volts).

The welding power source 205 is directly connected to the workpiece W,
The high voltage power source 206 for discharging is connected to the workpiece W via a current sensor 207.

The current sensor 207 detects a current change due to discharge between the electrode 209 and the workpiece W, and provides a signal to the control box 400.

The control box 400 controls the changeover switch 204.

That is, during normal welding, the selector switch 204 is switched to the welding power source 205 side, and when sensing the welding line, it is controlled to be switched to the discharge high voltage power source 206.

Further, the torch 116 has a built-in tightening means (not shown) as appropriate, so that the sensing operation can be performed with the protruding length of the consumable electrode 209 constant.

Hereinafter, using the welding torch 116 as a sensor, a work W (FIG. 3) is constructed by butting together a horizontal member W1 and a vertical member W2 extending in the Y-axis and Z-axis directions perpendicular to each other. The case of sensing the welding point at one end position of the corner welding line WL formed on the outside will be described with reference to the flowchart of FIG. 4.

First, the computer built in the control box 400 is put into the teaching mode, and the operation buttons (not shown) on the panel 5000 are manually operated to move the welding point WP of the torch 116 from the workpiece W near one end position of the welding MWL using a known playback method. Suitably remote starting position P1
Y-axis, Y-axis, and Z-axis direction position information to be located at X1. Yl
, Zl are input as one step of the user program together with the sensor command, and a series of user programs are further input.

Then, the computer is activated in auto mode, and the aforementioned user program is output step by step as command information accordingly.

Below, the operation according to the sensing steps will be explained one by one.

(1) First, it is determined whether the program includes sensor command information.

(2) If it is included, switch the selector switch 204 to the high voltage power source 206 for discharging.

(3) Next, adjust the amount of electrode protrusion.

This regulation is performed to make the amount of protrusion of the electrode 209 from the tip of the torch 116 constant when the torch 116 is used as a sensor.

First, the torch 116 is positioned at a predetermined position with respect to a predetermined reference point member.

For example, as shown in FIG. 1, a certain point on the outer circumference of the workpiece fixture 106 is set as the reference point Q, and the position of the torch 116 is controlled so that the welding point WP is located there.

Further, the consumable electrode supplying means 201 is activated to feed out the electrode 209, and if the tip thereof approaches the reference point Q and there is electrical continuity between the two, the supplying means 201 is activated by a signal from the current sensor 207. stop.

In this way, the amount of protrusion of the electrode 209 is regulated, and then the torch 1
16 by actuating the built-in tightening means (not shown) to tighten the electrode 2.
09 is fixed to the torch 116.

(4) Next, control the welding point WP of the torch 116 to the start position P1, and adjust the Y-axis and Z-axis at this position.
Axial position information X1. Take in Z.

(5) Displace the torch 116 by an appropriate amount downward in the Z-axis direction from the start position P1 and at a position P2 (Xl) where it faces the vertical member W2 when viewed in the X-axis direction.

¥1. Position control is performed on Z2).

(6) Move the torch 116 from the position P2 in the X-axis direction (leftward) toward the vertical member W2.

(7) During the movement, if the tip of the electrode 209 comes close to the vertical surface f1 of the vertical member W2, electricity will flow between them, a signal will be generated from the current sensor 207, and the movement of the torch 116 will stop, and the position P3 The X-axis direction position information X81 of (X81°Yl, z2) is taken in.

(8) When the step (7) is completed, move the torch 116 from the position P3 to the starting position P through the position P2.

Move back to .

(9) Movement distance in the X-axis direction of the torch 116 from the start position P to the (sensing) position P3 1X1-XS1
Calculate 1.

(10) Move the torch 116 at the start position P1 to the left in the X-axis direction from the start position P1 to 1X1-Xsll.

(n) Lowering the torch 116 from the position P4 in the Z-axis direction toward the vertical member W2.

(]2) During the lowering, if the tip of the electrode 209 comes close to the horizontal groove surface f2 of the vertical member W2, electricity will flow between the two;
The current sensor 207 issues a signal to stop the torch 116 from descending to its position P, (X,).

Yl, z8)'s Z-axis direction position information z8 is imported into the chess game (13
) The torch 116 is returned to a position P6 (X4°Yl +
Z6) position control.

(14) Move the torch 116 from the position P6 in the X-axis direction (leftward) toward the horizontal member W2.

(15) During the movement, if the tip of the electrode 209 comes close to the vertical groove surface f3 of the horizontal member W1, electricity will flow between them;
A portion of the current sensor 207 is emitted, the movement of the torch 116 is stopped, and the X-axis direction position information X82 at the position P7 (X82Y1.z6) is taken in.

α6) A position P s (Xs , Yt , Za
) to control the position.

07) This determines the completion of sensing, and the changeover switch 204 switches from the high-voltage power source 206 for discharge to the power source 205 for welding.
to return to.

(18) The X-axis direction and position P including position P5 from the imported X-axis direction position information X8□ and 2-axis direction position information Z8
Intersection position P9 with the Z-axis direction including 7 (Xs2Y1.z8
) and outputs the respective position information X62tY1tz8.

Of course, this intersection position P is between the upper surface f2 and the right side surface f3.
If they intersect at right angles, it becomes one point on the reed line WL.

With this, all sensing steps are completed, and a position command is executed for the torch 116 using the intersection position P as the welding point command position, but the actual welding point command position P1 is determined by the material of the workpiece W, the plate thickness, or the welding point. The intersection position P is determined in consideration of conditions and the like.

Position information shifted by a distance of △X in the X-axis direction and △Z in the z-axis direction from

Z 1 ”ZB±△Z).

As detailed above, according to the weld point detection method of the present invention, for a workpiece in which a groove is formed by abutting two members at right angles, there is some error in the shape and dimensions of the groove for each workpiece. Even if there is a slight deviation in fixing each workpiece to the workpiece fixture, sensing is performed for each workpiece based on a position sufficiently far from the workpiece, and the optimal welding point can always be detected.

In addition, since the torch electrode itself is used as a sensor, there is no structure around the torch that acts as a sensor, and it can easily penetrate into the groove area even if it is narrow, making it possible to reliably detect the corner weld line. By switching to the standard power source, you can immediately start welding work.

[Brief explanation of the drawing]

FIG. 1 is an overall perspective view of an automatic welding robot as an example of implementing the self-welding point detection method of the present invention, FIG. 2 is a side view including a block diagram showing a part of the automatic welding robot, and FIG. FIG. 4, which is an explanatory diagram of sensing in a workpiece applied to the present invention, is a flowchart of sensing. In the figure, 100 is the main body of an automatic welding robot, 116 is a torch, 200 is a power source, 201 is a consumable electrode supply means, 204
is a changeover switch, 205 is a welding power source, 206 is a high voltage power source for discharge, 207 is a current sensor, 20゛9 is a consumable electrode,
400 is a control box, 500 is a remote control panel, and W is a workpiece.

Claims (1)

[Scope of Claims] 1. An automatic welding robot that automatically welds the welding line of the workpiece by controlling the positions of the workpiece and the torch relative to each other based on commands from a control device, wherein the torch also serves as a sensor; The surface of the workpiece is detected by applying the detection power to the electrode and detecting the current state caused by the discharge between the electrode and the workpiece, and the three axes (
The above method for a workpiece in which a horizontal member and a vertical member extending in two selected axes (X-axis, Y-axis, Z-axis), for example, the X-axis and Z-axis directions are brought together to form a narrow groove on the outside. Controlling the relative position of the torch to a starting position (Xl, Zl) that is an appropriate distance outward from the groove,
The workpiece or the torch moves an appropriate distance in the Z-axis direction where the vertical member and the torch approach, and then moves in the X-axis direction to detect the vertical surface of the vertical member. After returning to the starting position, IX1+X811-H in the X-axis direction where the workpiece and torch approach each other.
It moves a short distance △l, moves from the moving position in the Z-axis direction where the workpiece and torch approach, detects the horizontal groove surface of the vertical member, and then returns a slight distance from the horizontal groove surface in the two-axis direction. After that, the horizontal member and the torch move toward each other in the X-axis direction to detect the vertical groove surface of the horizontal member, and the control device detects the X-axis direction position (X8□) of the vertical groove surface and the horizontal groove surface. A method for detecting a fillet welding point in an automatic welding robot, characterized in that a position (X8□, z8) consisting of two axial positions (Zs) of the front surface is output as a welding point command position. 2. The fillet welding point detection method in an automatic welding robot according to claim 1, wherein the detection power source is a low current and high voltage.