JPH11156577A - Butt position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with the processing which hardly receives the influences from a disturbance light and is carried out at higher speed. SOLUTION: The light is diagonally ejected from a slit laser oscillator 2 towards a step part S between works WA and WB, and the reflection light is received by a CCD line sensor 4. The butt position between the works WA and WB is calculated by a micro computer based on the position where the quantity of light received by the CCD line sensor 4 is changed from the high quantity of light to the low quantity of light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abutting position detecting device, and more particularly to an abutting position detecting device for detecting an abutting position having a step.

[0002]

2. Description of the Related Art For example, in a process of manufacturing an automobile, there is a process of joining blank materials having different thicknesses by welding. In such a process, it is necessary to accurately adjust the welding head to the butting position of both panels. Such abutting position detection is performed using a visual sensor or an optical cutting sensor when performing arc welding, for example.

[0003] In recent years, there has been a demand for a welding method that is performed at higher speed and with higher accuracy than arc welding. For this reason, laser welding may be used instead of conventional arc welding.

[0004] In laser welding, the laser beam diameter is about 0.5.
mm and very low welding speed of 5 m / min
And fast. For this reason, it is necessary to detect the butting position more accurately and at higher speed in laser welding than in arc welding.

[0005]

However, since the visual sensor detects the abutting position by binarizing or differentiating the image captured by the camera, the image is easily affected by disturbance light. For example, since the detection accuracy varies depending on the illuminance unevenness in the factory, as well as the change in the ambient brightness depending on the time zone such as day and night, it is not practical to use the laser welding at the production site.

In the light cutting sensor, light having a spread such as a slit laser beam is irradiated on the surfaces of both blank materials, and the shape of the two blank materials is detected by detecting the shape of the reflected light with a two-dimensional sensor. Since the calculation is performed and the abutting position is detected from the shape, the time required for calculating the shape and detecting the abutting position, that is, the scan time, is delayed.

Therefore, these conventionally used sensors cannot be applied to laser welding for detecting the butting position with higher accuracy and higher speed.

[0008] The present invention has been made in view of such problems of the prior art, and is hardly affected by disturbance light.
An object of the present invention is to provide a butt position detecting device that can be applied to welding performed at a higher speed.

[0009]

The above object is achieved by the following means.

(1) A butting position detecting device for detecting a butting position between a first work and a second work, wherein the device projects light obliquely toward the butting position where a step is formed. A light means, a light receiving means for receiving the reflected light from the stepped portion, and, in the reflected light received by the light receiving means, the first work and the second work from the position where the light amount changes from high light amount to low light amount. And a butting position calculating means for calculating the butting position.

According to this structure, light is projected obliquely toward the step at the boundary between the first work and the second work, and an area where light is not projected is provided at the abutting position of the two. be able to. By receiving the reflected light by the light receiving means, it is possible to distinguish between the area where the light is projected and the area where the light is not projected.

Further, in the reflected light received by the light receiving means, an abutting position between the first work and the second work is calculated from a position where the light amount changes from a high light amount to a low light amount, whereby the surrounding brightness is calculated. Can be determined regardless of the state of.

(2) The light emitted from the light emitting means is:
It is a laser slit light.

With this configuration, it is possible to project linear light on both works simultaneously across the first work and the second work. Therefore, the difference between the two reflected lights can be recognized by processing the one-dimensional data, and the speed of detecting the abutting position based on the respective reflected lights can be further increased.

(3) A butt position processing section for processing the butt position between the first work and the second work, and a processing for moving the butt position processing section to the butt position calculated by the butt position calculating means. And a section moving means.

With this configuration, the butting detection device according to the first or second aspect can be used for detecting a butting position at the time of working a butting position.

(4) The butt position processing section is a laser welding means for performing laser welding.

With this configuration, the butt detecting device according to claim 1 or 2 can be used for detecting a butt position during laser welding.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment described below shows an example in which the butt position detecting device of the present invention is applied to a laser welder used in the production of automobiles.

FIG. 1 is a block diagram showing the configuration of the present embodiment.

The configuration shown in FIG. 1 includes a CCD line sensor 4, a microcomputer 10, and a control device 20 for an NC machine tool.
And a laser welding head 1. Further, the microcomputer 10 includes a CPU 12 for performing arithmetic processing on a light receiving signal input from the CCD line sensor 4 and a memory 14 for storing master data of abutting positions.
The master data is data obtained by detecting the butting position of a dedicated blank material designed to obtain a reference butting position by the positioning detection device of the present embodiment.

The CCD line sensor 4 receives the light emitted by the light emitting means described later and outputs a signal corresponding to the received light amount to the microcomputer 10. The microcomputer 10 is a CCD
The signal from the line sensor 4 is sent to the CPU 12 and the memory 1
4 and performs NC processing based on the result of this calculation.
An instruction is given to the control device 20 of the machine tool. The control device 20 of the NC machine tool controls the laser welding head in accordance with the instruction, and performs laser welding at the butting position.

The CCD line sensor 4 described above
Corresponds to the light receiving means of the first aspect, and the microcomputer 10 corresponds to the butting position calculating means. Further, the control device 20 of the NC machine tool corresponds to a processing portion moving means of claim 3, and the laser welding head 1 corresponds to the laser welding means of claim 4.

FIG. 2 is a diagram schematically showing the configuration of the present embodiment.

The configuration of the present embodiment shown in FIG. 2 comprises a laser welding head 1, a slit laser oscillator 2, a CCD
It has a line sensor 4 and a distance measuring sensor 6. The laser welding head 1, the slit laser oscillator 2, and the CCD line sensor 4 are integrally supported by the working end of the same NC machine tool having three or more axes and move integrally. The distance measuring sensor 6 monitors the height of the slit laser oscillator 2 so as to keep the heights of the laser welding head 1, the slit laser oscillator 2, and the CCD line sensor 4 constant.

The slit laser oscillator 2 has the following features.
Corresponds to the light receiving means.

Below the laser welding head 1, a work W
A (WA) and a work WB (WB) are arranged. Each of the work WA and the work WB is a blank material of an automobile body before painting. As illustrated, the work WA and the work WB have different plate thicknesses, and the work WA is thicker than the work WB. Therefore, the work WA and the work WB
Has a step. Hereinafter, this step is referred to as a step S.

The slit laser oscillator 2 and the CCD line sensor 4 are arranged on a straight line orthogonal to the boundary between the work WA and the work WB. S is projected obliquely to the S, and the reflected light is transmitted to the CCD above the work WB.
All light is received by the line sensor 4.

The slit laser oscillator 2 oscillates a laser beam having a linear cross section, and can irradiate the work WA and the work WB simultaneously across the step S. Further, the CCD line sensor 4 has a plurality of photodiodes arranged in a row, and each photodiode receives light and accumulates signal charges corresponding to the intensity of the received light (light receiving intensity). The accumulated signal charge is C
The signal is transferred to a CD, and a signal having an intensity corresponding to the accumulated amount is output from the CCD.

Next, referring to FIG. 3, the work WA and the work W
The detection principle for detecting the butting position C with B will be described. FIG. 3A is a diagram illustrating a light emitting state of the slit laser oscillator 2 and a light receiving state of the CCD line sensor 4.
FIG. 3B is a diagram schematically showing signal charges accumulated in the photodiode of the CCD line sensor 4. FIG. 3C is a diagram showing a CCD line sensor 4 corresponding to FIG. FIG. 4 is a diagram showing the light reception intensity of FIG.

As shown in FIG. 3A, a slit laser beam L 1 is projected from the slit laser oscillator 2 to the step S. At this time, the slit laser oscillator 2 emits the slit laser light L1 at the incident angle θ from the thicker work WA side to the work WB side, that is, from the upper stage to the lower stage of the step S. The slit laser beam L1 projected at the incident angle θ is reflected at the reflection angle θ at the boundary between the work WA and the work WB. The slit laser light L2 which is the reflected light is received by the CCD line sensor 4.

In this embodiment, the incident angle θ is set to 45 degrees, and the CCD line sensor 4 is set to 45 degrees.
The reflected light can be received at an angle.

The slit laser beam L1 is projected so as to cross the step S, a part of which is reflected on the surface of the work WA, and another part is reflected on the surface of the work WB. At this time, an area E is formed on the surface of the work WB, which is shaded by the work WA and is not irradiated with the slit laser beam L1.
Therefore, the laser light is not reflected from the area E,
The photodiode at the position d in the line sensor 4 does not receive the reflected light. As a result, no charge due to the reflected light is accumulated in the photodiode at the position d as shown in FIG.

When an address is assigned to each photodiode and the received light intensity of the light received with respect to the arrangement of the addresses is obtained, the received light intensity of the photodiode at the position d as shown in FIG. It can be seen that it is clearly lower than. Therefore, the address of the photodiode at the position d can be determined by obtaining the relationship shown in FIG. 3C by measurement. From the address of the photodiode, a region E where the laser L2 light is not reflected in the work WB can be further determined. In the present embodiment, the point closest to the work WA in the area E is determined as the butting position.

In this specification, the amount of light received by the photodiode at the position d is referred to as low light amount, and the amount of light received by the photodiodes at other positions is referred to as high light amount.

In the butt position detection performed according to the principle described above, since the necessary data is obtained by a one-dimensional sensor, the butt position can be detected at a relatively high speed and laser welding is performed at a high speed. Particularly suitable for use in devices.

Next, a more specific example of the butting position detection of this embodiment will be described.

FIGS. 4 and 5 show the received light intensity of each photodiode with respect to the address arrangement of the photodiodes, and show the contrast of the butted position C. FIG.
FIG. 5 shows an example in which the step portion S forms a right angle.
Is an example in which the step portion S has R.

In the examples of FIGS. 4 and 5, the minimum value A is detected from the received light intensity data of the photodiodes of all addresses. Then, the offset amount is added to the detected minimum value A, and the added value is set as the allowable value B. In addition, the value of this offset amount is determined in advance by experiments or the like,
For example, it is stored in the memory 14.

Next, data having a light amount equal to or greater than the allowable value B is classified as high light intensity, and data having a value equal to or less than the allowable value B is classified as low light amount. Then, among the photodiodes that first change from the high light amount to the low light amount, those that receive reflected light from a position closer to the work WA are denoted by C ′. That is, the abutting position C is determined by the slit laser light L2 that should be received by the photodiode C '.
(FIG. 3 (A)) is located at a position where the light is reflected.
Butt position C based on the address of photodiode C '
Can be detected.

In the present embodiment, the photodiode C 'measured in advance and the position of the laser welding head 1 at this time are stored in the master data. Therefore, the microcomputer 10 (FIG. 1) compares the detected photodiode C 'with C' stored in the master data, and moves the laser welding head 1 by an amount corresponding to the shift amount. It is instructing the control device 20 of the machine.

In the example of FIG. 5 where the step S at the abutting position C has R, more measurement points are recorded than in the example of FIG. 4 until the minimum value A is obtained. Also, it can be seen that the received light intensity is gradually decreasing. But,
In FIG. 5, the position of the photodiode C ′ detected by the same method as in the example of FIG. 4 corresponds to the abutting position C. Therefore, in the present embodiment, even if the step portion S has a right angle,
The abutting position C can be detected even in an R shape.

The detection example described above is based on the case where the photodiode receiving reflected light and the photodiode receiving no light are divided into a high light amount and a low light amount based on the minimum value A of the received light data obtained by the CCD line sensor 4. And has been identified. Therefore, for example, even if the illumination light around the photodiodes changes, in this case, the light receiving intensities of all the photodiodes change uniformly. Therefore, the change of surrounding illumination light is
It does not affect the detection of the photodiode C 'of the present embodiment and, consequently, the detection of the positioning unit C.

Therefore, the present embodiment is advantageous in putting it to practical use at a production site where the surrounding lighting conditions may change.

FIG. 6 is a flowchart showing the processing of the present embodiment described above.

The process shown in FIG. 6 is started when the laser welding device is turned on (S1). When the switch of the laser welding device is turned on, the slit laser oscillator 2
Emits slit laser light (S2). The oscillated slit laser light is received by the photodiode at each address of the CCD line sensor. The light receiving intensity of the light received by the photodiode at each address is acquired by the CCD line sensor as received light intensity data (S3).

When the acquisition of the photodiode data of all addresses is completed (S4), the minimum value of the received light intensity data among the acquired data is detected (S5), and this value is stored in the memory 14 (S6). The CPU 12 obtains the address of the photodiode corresponding to the abutting position by, for example, adding an offset amount to the stored minimum value of the received light intensity, and compares this address with that of the master data to perform the calculation and comparison processing. This is performed (S7), the amount of deviation from the butted position of the master data is fed back to the control device 20 of the NC machine tool, and the amount of movement of the NC machine tool is determined (S8).

Next, the NC machine tool is moved according to the moving amount determined in step 8 (S9), and welding is performed (S1).
0). Thereafter, if the laser welding switch is turned off, the process is terminated (S11), and if not, the process returns.

In the present embodiment described above, light is projected obliquely from the upper side of the step S toward the step S at the boundary between the work WA and the work WB, and the light is projected at the abutting position of the two. Is provided, and the reflected light is detected by a CCD line sensor, so that the abutting position between the work WA and the work WB can be detected.

The slit laser oscillator 2 emits light across the step S at the boundary between the work WA and the work WB, and receives reflected light of the light emitted by the CCD line sensor 4. Thus, data necessary for detecting the butting position can be acquired by one measurement. Therefore, the speed of detecting the butting position can be further increased.

Further, the intensity of the light received by the CCD line sensor is divided into a high light amount and a low light amount based on an allowable value based on the minimum value obtained by the measurement, so that the ambient brightness state and its change can be obtained. Regardless, it is possible to accurately determine the butting position.

Further, the laser welding head 1 for processing the butting position of the workpiece WA and the workpiece WB, and the control device 20 of the NC machine tool for moving the laser welding head 1 in accordance with the butting position determined by the microcomputer 10 are further provided. By having this, it becomes possible to use the butting position detecting device of the present embodiment to accurately adjust the laser welding head 1 to the butting position. With such a configuration, it is possible to provide a laser welding apparatus capable of performing laser welding at a high speed and accurately at the abutting position between works without being affected by disturbance.

[0053]

According to the first aspect of the present invention, an area where light is not projected is provided at the abutting position of the first work and the second work, and the reflected light is received by the light receiving means to determine the abutting position. Detected.

Therefore, it is possible to efficiently emit light to the position where the abutting position is detected, and the speed of detecting the abutting position can be increased.

Further, in the reflected light received by the light receiving means, the butting position between the first work and the second work is calculated from the position where the light amount changes from the high light amount to the low light amount, so that the surrounding brightness is calculated. The determination of the butting position can be performed irrespective of the state.

Accordingly, it is possible to provide a butting position detecting device which can cope with processing performed at a higher speed and which is hardly affected by disturbance light.

According to the second aspect of the present invention, the difference between the two reflected lights can be recognized by the one-dimensional sensor, and the speed of detecting the abutting position based on the respective reflected lights can be further increased.

The third aspect of the present invention is the first or second aspect.
The butting detection device described in (1) can be used for abutting position detection at the time of butting position processing.

The invention according to claim 4 is the first or second invention.
Can be used for detecting a butt position during laser welding.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a configuration of an embodiment of the present invention.

3A and 3B are diagrams illustrating a detection principle for detecting a butting position according to an embodiment of the present invention. FIG. 3A illustrates a light emitting state of a slit laser oscillator 2 and a light receiving state of a CCD line sensor. FIG. 3B is a diagram schematically showing electric charges accumulated in a photodiode of a CCD line sensor, and FIG. 3C is a diagram corresponding to FIG. 3B.
It is a figure showing the light reception intensity of a line sensor.

FIG. 4 is a diagram illustrating an example of detecting a butting position according to an embodiment of the present invention, particularly an example in a case where a step portion forms a right angle.

FIG. 5 is a diagram illustrating an example of detecting a butting position according to an embodiment of the present invention, particularly when the step portion has an R;

FIG. 6 is a diagram illustrating a process according to an embodiment of the present invention as a flowchart.

[Brief description of reference numerals]

 REFERENCE SIGNS LIST 1 laser welding head (laser welding means) 2 slit laser oscillator (light emitting means) 4 CCD line sensor (light receiving means) 6 distance measuring sensor 10 microcomputer (butting position calculating means) 12 CPU 14 memory C ... Butting position S ... Stepped part WA ... Work WA (first work) WB ... Work WB (second work)

Claims (4)

[Claims] 1. A butting position detecting device for detecting a butting position between a first work and a second work, wherein the light is projected obliquely toward the butting position where a step is formed. Means, light receiving means for receiving the reflected light from the stepped portion, and, in the reflected light received by the light receiving means, the first work and the second work from a position where the light quantity changes from a high light quantity to a low light quantity. And a butting position calculating means for calculating a butting position of the butting position. 2. The butting position detecting device according to claim 1, wherein the light projected from said light projecting means is laser slit light. 3. A butt position processing section for processing a butt position between the first work and the second work, and a processing for moving the butt position processing section to a butt position calculated by the butt position calculating means. The butting position detecting device according to claim 1 or 2, further comprising a unit moving unit. 4. The butting position detecting device according to claim 3, wherein the butting position processing section is a laser welding means for performing laser welding.