JPS5820707B2 - 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 fillet 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 fillet weld point of a workpiece made by abutting two members extending in two axial directions orthogonal to each other can be accurately detected even if there is some dimensional error. The object of the present invention is to provide a method for detecting corner 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 panel 500.

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.

This rotating frame body 104 includes a central member 104c and side frames 104a and 104b extending in parallel from both ends of the central member 104c, and the side frames 104a and 104b are connected to the support columns 102 and 104b, respectively.
3. It is rotatably supported.

A forward/reverse motor 105 with a speed reducer and a brake is further mounted on the back of the column 103, and the rotating frame 104 is rotated around the horizontal axis H (in the direction of the arrow Y) by driving this motor 105. It is a good idea to let it happen.

A forward/reverse motor 107 with a speed reducer and a brake is provided on the back surface of the center member 104c at approximately the center of the center member 104c. The workpiece mount 106 is pivotally supported so as to be rotatable in the direction (direction).

Reference numerals 108-109 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 108 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 around a vertical axis M (in the direction of arrow φ). A tool 115 is provided.

The tip welding point wP of the torch fixture 115 is aligned with the vertical axis M.
A torch 116 is fixedly mounted as shown above.

Further, the torch mount 115 is configured to control the turning angle around the vertical axis M by a power source built into the support member 114, although details are not shown.

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 105-107, the left and right moving body 111,
The forward/reverse movement, movement, and rotation of the longitudinally moving body 112, the vertically moving body 113, the torch mount 115, etc., as well as the power supply voltage, current, etc., are automatically controlled by the control box 400 and the welding control device 300 according to a predetermined program. It is.

Thereby, 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 the best posture under the welding conditions. do.

A remote control panel 500 is provided for the purpose of creating additional programs or for manual operation.

Thus, the robot body 100 has each axis x, y
,z.

M, has degrees of freedom about the six axes of H.

Then, such a main body 100, devices 200-300,
For more detailed configuration, operation, and operation of 400 and 500, see, for example, Japanese Unexamined Patent Publication No. 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 impart a bending direction to the consumable electrode 209.

In this embodiment, a flexible tube for guiding a consumable electrode 209 is formed in the force device 202 in a loop shape, so that the tip of the consumable electrode 209 is always bent to a certain degree.

Of course, the force device 202 may be of a type other than this embodiment, for example, a guide roller that clamps the consumable electrode in 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 selects either the welding power source 205 or the high voltage power source 206 for discharge as a detection power source via a changeover switch 204. It is possible to connect to the

As is well known, the welding power source 205 is a large current low voltage power source 2.
06 is a low current 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.

A 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 changeover switch 204 is switched to the welding power source 205 side, and when sensing the weld line', the switch 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 while the protruding length of the consumable electrode 209 is kept constant.

Hereinafter, using the welding torch 116 as a sander, a horizontal member W1 and a vertical member W2 extending in the X-axis and Z-axis directions, which are orthogonal to each other, are brought together to form a workpiece W (FIG. 3). The case of sensing the welding point at one end position of the corner self-welding line WL formed in will be described with reference to the flowchart of FIG. 4.

First, the computer built in the control box 400 is set to the teaching mode, and the operation button (not shown) of the one channel 500 is manually operated, and the welding point WP of the torch 116 is placed near one end of the welding line WL using the known play pack method. X-axis, Y-axis, and Z-axis direction position information X1. which should be located at a start position P appropriately remote from W. Y7. Zl
is input as one step of the user program together with the sensor command, and a series of user programs are also input.

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

The operation of each sensing step will be explained below.

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

(If it is included, switch the changeover 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 lying 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 certain position with respect to a certain 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, 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. If the tip of the electrode 209 is close to the reference point q and there is electrical continuity between the two, a signal from the current sensor 207 causes the supplying means 201 to move out. stop operating.

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, welding point WP of torch 116 (electrode 209
) is positionally controlled to the start position P1, and position information X1. Take in Zl.

(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.

Yl, 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 emitted from the current sensor 207, and the movement of the torch 116 will stop, and its position P3 (Xsl.

The X-axis direction position information Xs1 of Yl, z2) is taken in.

(8) When step (7) is completed, the torch 116 is moved from the position P3, through the position P2, and back to the starting position P1.

(9) The torch 116 that has returned to the starting position P1 is displaced to the left in the X-axis direction by an appropriate amount, and is moved to a position P4 (X4°Yl, Zl) facing the horizontal member W1 when viewed in the Z-axis direction.

(10 The torch 116 is lowered in the Z-axis direction from the position P4 toward the horizontal member W.

αW When the tip of the electrode 209 comes close to the horizontal surface f2 of the horizontal member W2 during the lowering, a current flows between the two, a signal is generated from the current sensor 207, and the lowering of the torch 116 is stopped, and the position p, ( x.

The two-axis direction position information Zsl of Yl, Zsl) is taken in.

@ The torch 116 is moved from the position P, through the position P4, and back to the start position P.

α3 The captured X-axis direction position information Xs1 and Z
Intersection position P6 (Xs
l tYx tZsl ) is calculated.

1141 From the start position P1 to the intersection position P6
Displacement position P7 (
X7, Yt-Z7).

◇→ The torch 116 is lowered from the displaced position in the Z-axis direction toward the horizontal groove surface f3 of the vertical member W2.

(IQ During the lowering, if the tip of the electrode 209 approaches the horizontal groove surface f, electricity will flow between the two, and the current sensor 2
07 to stop the descent of the torch 116 and move to its position P8 (X7, Yl).

Zs2. ) is taken in the two-axis direction position information Zs2.

#P where the torch 116 is returned a little distance (1 to 2 m) upward in the Z-axis direction from the position P8.

Located at (X7, Yl, z,)! 1m long.

Day 6: Move the torch 116 from the position P in the X-axis direction (leftward) toward the horizontal member W1.

(g) During the movement, if the tip of the electrode 209 comes close to the vertical groove surface f4 of the horizontal member W1, electricity will flow between them;
A signal is emitted from the current sensor 207, the movement of the torch 116 is stopped, and the X-axis direction position information Xs2 of the position P1° (Xs2, Y, Z,) is taken in.

(c) The torch 116 is placed at the position P.

Position P returned slightly (1 to 2 mm) to the right in the X-axis direction from
11 (X1t, Yl-Zo).

Cη This determines that sensing is complete, and the changeover switch 204 switches from the discharge high-voltage power source 206 to the welding power source 205.
to return to.

(To) The captured X-axis direction position information X s 2
and the X-axis direction and position P, including the Z-axis direction position information Zs2 to position P8.

The intersection position P12 (XS2 s
Yl t Zs2 ), and each position information X
Output s2, Yl, and zs2.

Of course, this intersection position P12 will be one point on the welding line WL if the horizontal groove surface f3 and the vertical groove surface f4 intersect at a right angle.

With this, all sensing steps are completed, and a position command is executed for the torch 116 using the intersection position P12 as the welding point command position, but the actual welding point command position Pi is determined by the material of the workpiece W, the plate thickness, or the welding conditions. Taking into account the
l, Zi=Zs2±△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 drawings]

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. 3 4 is an explanatory diagram of sensing in a work applied to the present invention, and FIG. 4 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, 209 is a consumable electrode, 4
00 is the control box, 500 is the remote control panel,
W is work.

Claims (1)

[Scope of Claims] 1. An automatic welding robot that automatically welds the welding line of the workpiece by controlling the relative positions of the workpiece and the torch according to commands from a control device, wherein the torch also serves as a sensor, and the torch A detection power source is applied to the electrode, and the surface of the workpiece is detected by the energization state caused by the discharge between the electrode and the workpiece, and the three axes (
The torch is applied to 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 the Z-axis, are butted together to form a groove in a narrow area on the outside. The relative position of the workpiece is controlled to a starting position (Xl, Z,) which is suitably remote outward from the groove, and the torch is positioned at a position Z where the vertical member and the torch approach each other.
Move an appropriate distance in the axial direction, then move in the X-axis direction to detect the vertical surface of the vertical member (X51), then return to the starting position and move an appropriate distance in the X-axis direction so that the horizontal member and the torch approach Then move in the Z-axis direction to detect the horizontal surface of the horizontal member (Zsl), return to the starting position again, and then move the detected XSI, Zsl
The position is controlled to a displacement position slightly shifted in the X-axis and Z-axis directions, where the workpiece and the torch approach each other from the position where
From the displacement position, move in the Z-axis direction where the vertical member and the torch approach to detect the horizontal groove surface of the vertical member (Zs2)
, further, after returning slightly from the horizontal groove surface in the Z-axis direction, 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. Positions Xs2 and Zs2 consisting of the X-axis direction position Xs1 of the tip surface and the two-axis direction position Zs1 of the horizontal groove surface
A method for detecting a fillet welding point in an automatic welding robot, the method comprising: outputting a welding point command position 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 area power source is a small current and high voltage.