JPH0545122A - Detecting method of welding line of automatic welding apparatus - Google Patents

Abstract

PURPOSE:To obtain a detecting method of a welding line of an automatic welding apparatus which enables reliable detection of the welding line even in butt welding of thin plates wherein a route gap is zero. CONSTITUTION:At an ordinary time, a slit-shaped laser light L emitted from a projector 15 is applied to a welded part so that it traverses a welding line WL. A reflected light from the welded part is sensed by a sensor 17, a difference in lightness thereof is discriminated by a control element and thereby the welding line WL is detected. In the case when deformation of a base material W due to a welding heat becomes large and when discrimination between a difference in brightness due to this deformation and a difference in the brightness due to the traverse of the welding line WL becomes impossible and consequently it is difficult to detect the welding line WL, as in the case of butt welding of thin plates wherein a route gas is zero, a resolution is increased by bringing the sensor 17 near to the welded part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding line detecting method for an automatic welding device, and more particularly to a welding line detecting method for an automatic welding device which is suitable for detecting a welding line in butt welding with a zero root gap of a thin plate. is there.

[0002]

2. Description of the Related Art Unlike the spot welding, the work of arc welding is originally in the field of work carried out by skilled workers supported by many years of experience and achievements called welders,
It is an advanced task that cannot be accomplished by amateurs with a little practice. Therefore, even when automatic welding is performed by the welding robot, a function sufficient to realize such a high skill of a welding worker is naturally required.

One of the most basic functions is a function of detecting a welding line. In particular, as a method of detecting the weld line in butt welding with a zero root gap,
Irradiate a slit-shaped laser beam onto the welding line,
The brightness distribution of the reflected light is represented by CCD (charge coupled devic
e) There is a method to detect the welding line by distinguishing with a camera. In this method, when the base material is cut, the reflection intensity is reduced due to minute deformation that occurs in the cut portion, so the CCD camera detects the "dark" portion, and the control unit that receives this dark portion signal detects the welding line. To detect. Therefore, it is said that the weld line can be detected even if the root gap is zero.

[0004]

However, in such a conventional technique, in the case of a thin plate, since the microdeformation itself occurring in the base metal cutting portion is small, it is possible that the base metal fluctuates or deforms during welding. There is a risk that the welding line may be lost because it cannot be distinguished from the "dark" part.

The present invention was made by paying attention to such a conventional technique, and a welding line of an automatic welding apparatus capable of surely detecting a welding line even in butt welding of thin plates having a zero root gap. A detection method is provided.

[0006]

A welding line detecting method for an automatic welding device according to the present invention irradiates a welding site with slit-like light emitted from a light projector, and a sensor reflects light reflected from the welding site. In the welding line detection method of the automatic welding device in which the control unit determines the welding line by receiving the light and the brightness signal from the sensor, when the control unit cannot determine the welding line, the sensor is brought close to the welding site. The method is to increase the resolution.

[0007]

According to the welding line detecting method of the automatic welding apparatus according to the present invention, the slit-shaped laser light emitted from the projector is normally applied to the welding portion while traversing the welding line and reflected from the welding portion. The light is received by the sensor, and the control unit determines the difference in the brightness to detect the welding line. Then, the deformation of the base metal due to welding heat becomes relatively large as in the case of butt welding with a thin root gap of zero, and it is possible to distinguish between the difference in lightness and darkness due to this deformation and the difference in lightness and darkness due to crossing the welding line. When it is difficult to detect the weld line because it disappears, the resolution is increased by bringing the sensor close to the welded part.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS.
It will be explained based on. Referring to FIG. 2, the automatic welding apparatus using the welding robot 1 includes a sensor controller (control unit) 3, a robot controller (control unit) 5, and a welding power source 7 in addition to the welding robot 1.

Referring to FIG. 3 together with FIG. 3, the welding robot 1 is a well-known welding robot and can normally be controlled to rotate about 6 axes, and a torch 11 and a welding line WL are attached to the tip of an arm 9 which can be freely moved.
The detection unit 13 for detecting As shown in FIG. 4, the detection unit 13 is a semiconductor laser (light projector) 15 that emits a slit-shaped laser beam L to a welding portion.
And a CCD camera (sensor) 17 that receives the reflected light of the laser light L at the welding site. Here, the CCD camera 17 is composed of a CCD camera body 19 and a lens 21 provided below it. The CCD camera body 19 can be moved up and down by an air cylinder 23 provided above it. That is, the CCD camera 17 can detect the area within the range indicated by AR1 in the figure at the normal time, but the CCD camera body 19 is detected downward to detect within the narrow area AR2. This is for narrowing the detection range and improving the resolution.

In the detection unit 13, the slit-shaped laser light L emitted from the semiconductor laser 15 is applied to the surface of the base metal W at the welding site while straddling the welding line WL, and the reflected light is passed through the lens 21. The light is received by the CCD camera body 19, and a bright / dark signal of the welding site is emitted from the CCD camera body 19 to the sensor controller 3.

The sensor controller 3 receives the light / dark signal from the CCD camera body 19 and detects the position of the welding line WL from the difference between the light and dark. That is, at the position of the welding line WL, the irradiated laser light is diffusely reflected and becomes "dark", so this portion is determined to be the welding line WL. The robot controller 5 uses the position of the welding line WL as coordinate data.
To leave. The robot controller 5 converts the obtained coordinate data into a robot coordinate system and transmits the coordinate data to the welding robot 1, and accordingly the welding robot 1 moves the arm 9 to move the torch 11 to the given coordinate position. Accurate placement and welding work.

Next, the control contents of the robot controller 5 will be described with reference to the flowchart of FIG. First, the coordinates of the terminal portion P1 of the welding line WL are recognized (S1 in FIG. 1).
Step). Then, the coordinates of the starting end P2 of the welding line WL are recognized (step S2). The welding line WL is calculated from the inputted coordinates of the end portion P1 and the start end portion P2 (step S3). Then, the welding robot 1 is instructed to start welding from the starting end portion P2 (S4 step). The welding robot 1 advances welding from the starting end portion P2 to the terminating end portion P1 along the welding line WL calculated in step S3 (S).
5 steps), the detection unit 13 always confirms the welding line WL during this welding operation (S6 step). And
If the welding line WL is recognized, the confirmed welding line W
An error between the coordinate position of L and the coordinate position where welding is actually performed is obtained (S7 step), and it is determined whether the error is within the allowable range (S8 step). Determines whether or not the welding work has been continued and the end portion P1 has been reached (S9 step). Then, when the end portion P1 is reached, the welding operation is ended (step S10), but if the end portion P1 is not reached yet, the process returns to step S5 and steps S5 to S9 are repeated until the end portion P1 is reached. During this time, if the weld line WL cannot be confirmed in step S6, the CCD camera body 19 of the detection unit 13 is moved closer to the weld site by the air cylinder 23 to increase the resolution, thereby enlarging the observation site and increasing the weld line WL.
Is confirmed (step S11), the process returns to step S6, and when the welding line WL is recognized, the process proceeds to step S7.
If the error exceeds the allowable range in step S8, the coordinates of the detected welding line WL are converted into the robot coordinate system (step S12), and the torch 11 is placed at the coordinate position (step S13). .. Then, returning to step S9, the welding operation is repeated and continued until the end portion P1 is reached.

Thus, the welding line WL is always maintained during the welding operation.
Since the welding work is performed while confirming, the precise position can be welded. When the base material W fluctuates or deforms due to welding heat and the welding line WL cannot be confirmed, the CCD camera body 19 of the detection unit 13 is lowered by the air cylinder 23 to bring it closer to the welding site, and the resolution is increased. Therefore, the weld line WL can be reliably detected even in the butt welding of the thin plate with zero root gap. Also, in the butt welding of the base material W having a cut surface with a small deformation in the cut portion such as laser cutting, the welding line WL is also used.
Can be detected, which improves the welding function. Further, since it is only necessary to recognize the terminal end P1 and the starting end P2 of the welding line WL, normal welding can be performed by simple teaching as in the conventional case.

In the above embodiment, the CCD camera main body 19 is moved up and down by the air cylinder 23 to bring it closer to the welding site. However, the vertical moving means is not limited to the air cylinder 23, and any mechanical means such as mechanical means may be used. Means may be used. Further, although the resolution is improved by moving the CCD camera body 19 up and down, the invention is not limited to this, and the resolution may be increased by moving the lens 21 up and down.

[0015]

The welding line detecting method of the automatic welding apparatus according to the present invention has the above-described structure, and since the welding work is always performed while confirming the welding line during the welding work,
The exact position can be welded. Then, the deformation of the base metal due to the welding heat becomes relatively large, and when it is difficult to detect the welding line because the difference between the lightness and darkness due to this deformation and the difference between the lightness and darkness due to crossing the welding line cannot be determined, The resolution of the sensor is improved by bringing the sensor closer to the welding site. As a result, the weld line can be reliably detected even in the butt welding of thin plates with a zero root gap.

[Brief description of drawings]

FIG. 1 is a flowchart showing the control contents of a robot controller in an automatic welding apparatus using a welding line detection method for an automatic welding apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of an automatic welding apparatus using the welding line detection method of the automatic welding apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a torch and a detection unit provided at the tip of the arm of the welding robot.

FIG. 4 is an explanatory view showing a main configuration of a detection unit for carrying out the welding line detection method of the automatic welding device according to the present invention.

[Explanation of symbols]

 3 Sensor controller (control unit) 5 Robot controller (control unit) 15 Semiconductor laser (light projector) 17 CCD camera (sensor) WL Welding line L Laser light

Claims (1)

[Claims] 1. A welding part is irradiated with slit-shaped light emitted from a light projector, and a sensor receives the reflected light from this welding part, and the control section discriminates a welding line based on a bright / dark signal from this sensor. In the welding line detection method for an automatic welding device, when the control unit cannot determine the welding line, the resolution is enhanced by bringing the sensor closer to the welding site, and the welding line detection method for the automatic welding device.