JPH08300178A - Laser beam machine - Google Patents

Abstract

PURPOSE: To provide a laser beam machine that can obtain teaching data to attain a high machining precision with a simple teaching operation. CONSTITUTION: An outgoing optical system is provided with a CCD camera 13 for the purpose of photographing a prescribed areas including machining lines for a work. An image processor 21 performs a predetermined line-detecting process against an image including the lines to be machined from the CCD camera 13 in accordance with the movement of the outgoing optical system or a work table so as to detect the machining lines that may be superposed on those of the work. A controller part 23 detects positional deviation between the reference points, which are preliminarily set in the image of the CCD camera 13 and which are supposed to be the optical axis of the laser beam, and the closest points on the detected machining lines, thereby controlling the driving part of the outgoing optical system or the work table in order to correct this positional deviation. Using as teaching data the positional data thus obtained of the outgoing optical system or the work table, subsequent automatic welding or cutting is performed by a laser beam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus for displacing an emission optical system for irradiating a laser beam or a work for welding or cutting the work.

[0002]

2. Description of the Related Art An example of this type of laser processing apparatus will be schematically described with reference to FIG. In FIG. 8, the first ball screw mechanism 61 allows a work table 65 on which a work (not shown) is mounted to be moved in one direction (herein referred to as the x-axis direction). Further, the first ball screw mechanism 61 is mounted on the second ball screw mechanism 62 so as to be movable in the y-axis direction. Further, an arm 64 is attached to the third ball screw mechanism 63 so as to be movable in the z-axis direction, and an emission optical system for laser beam irradiation and this is driven in the x-, y-, and z-axis directions on the arm 64. A laser irradiation unit 100 including a drive unit is attached.

A drive unit 6 incorporating a laser oscillation source and the like
A cable-shaped optical fiber 67 is led out from the optical fiber 6, and the optical fiber 67 is connected to the arm 64 and the laser irradiation unit 1.
Laser irradiation unit 1 in a deformable state in conjunction with movement of 00
00 is connected. For example, a YAG laser device is used as the laser oscillation source.

In this type of laser processing apparatus, a teaching box (not shown) is used for teaching or teaching support.
Is used. This teaching box is equipped with a switch for switching between teaching and actual laser processing, a switch for starting and stopping the device, buttons for remote control operation, etc. And the displacement of the output optical system can be controlled. The teaching box is attached to the main controller 69 or can be remotely operated by wire. The main control unit 69 is
Operation panel 69-1 for inputting various setting values
And a monitor 69-2 for displaying various data.

When performing laser processing, for example, welding, teaching is performed in advance for each work using a teaching box. That is, before starting welding by automatic control, the operator operates the teaching box to teach.

With reference to FIGS. 11 to 14 as well, teachings when a CCD camera is mounted in the emission optical system will be described. When the operator selects the teaching mode with the switch of the teaching box 68, the teaching beam is emitted from the emission optical system 70. The operator refers to this teaching beam as shown in FIG. 11 and monitors 69-2.
The output optical system 70 is arranged so that the work line L1 to be welded on the work 71 is within the field of view of the CCD camera displayed in FIG.
Alternatively, the work table 65 (FIG. 8) is moved (first step). Since the teaching beam only needs to have a guiding function, a beam different from the laser beam, for example, a He-Ne beam is usually used. Further, the teaching beam is once stopped when the first step is completed.

Next, as shown in FIG. 12, the operator sets the center point (reference point) set in the image of the CCD camera.
The position of the emission optical system 70 is finely adjusted so that C1 is located on the line L1 to be processed. In FIG. 12, the line L1 to be processed is enlarged and is shown by hatching with a narrow interval. The center point C1 is set in advance so as to be the optical axis position of the laser beam in actual welding. Then, while maintaining this state, the output optical system 70 or the work table 65 is moved to move the center point C1 by a predetermined distance in the extending direction of the line L1 to be processed (second step).

FIG. 13 shows a step (third step) in which the focal point of the laser beam for processing to be irradiated is made to coincide with the processing point on the line L1 to be processed, and FIG.
Shows a step (fourth step) of making the optical axis of the laser beam for processing to be irradiated perpendicular to the work 71 when the processed surface of the object is a curved surface, each of which has an autofocus function. Automation is realized by a function called the auto normal function. In any case, the operator executes the above-mentioned first to fourth steps at a predetermined distance, usually at intervals of 100 mm, inputs teaching data each time, and stores the teaching data in the storage device. That is, the operator operates the exit optical system 70 from the start point to the end point of the line L1 to be processed obtained as described above.
The position data of the work table 65 is stored in the storage device built in the main control unit 69 as teaching data for each predetermined distance. In actual welding, the main control unit 69 reads the teaching data from the storage device and uses the read teaching data to output the optical system 70 or the work table 65.
Control the movement of.

[0009]

However, the CCD
Even when looking at the enlarged display screen imaged by the camera, since the operator performs the movement operation of the emission optical system 70 or the work table 65, the emission is performed so that the center point C1 of the image always coincides with the work line L1 to be welded. It is difficult to move the optical system 70 or the work table 65, and the time for teaching becomes long. This poses a serious problem particularly in high-precision processing with a YAG laser.

In view of the above problems, it is an object of the present invention to provide a laser processing apparatus which can obtain teaching data for obtaining high processing accuracy with a simple teaching operation.

[0011]

According to the present invention, there is provided a work table equipped with the emitting optical system and the work so that an optical axis of a laser beam emitted from the emitting optical system moves on a work line of the work. In a laser processing apparatus that performs laser processing by moving at least one of the two, C for photographing an area of a predetermined range including the line to be processed of the workpiece
A CD camera is provided in the emitting optical system, and a predetermined line detection process is performed on an image including the processed line from the CCD camera according to the movement of the emitting optical system or the work table to perform the line detection processing. An image processing unit for detecting a processing line overlapping the processing line, and the CCD
Detecting a positional deviation between a reference point that is preset in the image of the camera and should be the optical axis of the laser beam, and the closest point on the detected machining line, and the exit optics is configured to correct this positional deviation. A controller for controlling a system or a drive unit of the work table, and performing subsequent automatic welding or cutting with a laser beam using the resulting position data of the emission optical system or the work table as teaching data. Characterize.

The image processing unit detects the processed line by performing line detection processing such as Hough conversion processing as the predetermined line detection processing.

Further, the controller calculates a positional deviation between the reference point and the closest point on the detected machining line, and expresses a position to be moved in order to correct the positional deviation in machining point coordinates. It is composed of an arithmetic unit for outputting and a control unit for controlling the drive unit of the emitting optical system or the work table based on the processing point coordinates.

[0014]

According to the present invention, the teaching work can be performed only by moving the emitting optical system or the work table so that the field of view by the CCD camera does not deviate from the work line to be processed. Alignment is done automatically.

[0015]

DETAILED DESCRIPTION OF THE INVENTION A laser processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

[First Embodiment] FIG. 1 shows a schematic structure of an emission optical system 10 used in the present invention, and may be used instead of the emission optical system described in FIG. The laser beam B1 from the laser oscillation source is introduced into the emission optical system 10 through the optical fiber, the angle is changed by the mirror 11, and the work 20 is irradiated through the processing lens 12. When teaching is performed using a teaching box, the He-Ne beam B2 is supplied through an optical fiber and irradiated onto the work 20, as described later. A CCD camera 13 is provided above the emission optical system 10, and the CCD camera 13 takes an image of a predetermined area including a work line to be welded through the observation lens 14.

Optical axis of CCD camera 13 and laser beam B
The optical axis of 1 is set in advance to match,
Moreover, the CCD camera 13 is placed at the focus position of the laser beam B1.
The focus is adjusted to fit. In other words,
When the optical axis and the focus of the CCD camera 13 are aligned with the line to be processed on the work 20, the optical axis and the focus of the laser beam B1 are also aligned with them. This is the same for the He-Ne beam B2.

The resolution of the image by the CCD camera 13 is 256 × 256 pixels, and one pixel is about 0.02 (m
m). Also, the field of view of the CCD camera 13 is 5 × 5.
(Mm). This considers that when the field of view is narrowed, the photographed region is enlarged and the detection accuracy is improved, but the work of the operator accompanying the teaching becomes fine and the work amount increases. The present invention reduces this workload. The image is represented by 256 gradations of color (luminance) according to the intensity of light.

FIG. 2 shows a structure of the laser processing apparatus according to the present invention, which is necessary for teaching or teaching support using a teaching box. The image from the CCD camera 13 is sent to the monitor 69-2 provided in the main controller 69 for display, and is also sent to the image processing device 21.
The image processing device 21 performs image processing described below to detect a processing line that matches the processing line on the work 20.
The detected machining line is sent to the arithmetic unit 22. The arithmetic unit 22 detects the processing line and the center point of the image set in the CCD camera 13 (reference point, that is, the center point C in FIG. 12).
1) That is, the deviation from the focus position of the laser beam is detected, and the coordinates of the processing point indicating how much the emitting optical system 10 or the work table 65 should be moved in order to correct this deviation are calculated.

That is, in the arithmetic unit 22, the focus position of the processing point, the coordinate system of the field of view of the CCD camera 13, the processing axis, that is, the position of the mechanical coordinate system of the laser beam B1 from the operation panel 69-1 and various sensors (not shown). Data showing the relationship is given. Then, the position of the processing line and the position of the processing point on the image on the monitor 69-2 are determined. Arithmetic unit 22
Calculates the amount of movement for moving the exit optical system 10 to the next processing point position, and outputs the calculation result to the control unit 23 as processing point coordinates. The control unit 23 controls the movement of the emission optical system 10 and the work table 65 based on the processing point coordinates to match the focus of the laser beam for processing with the detected processing line. Since the arithmetic unit 22 only needs to have an arithmetic function, it may be included in the control unit 23 and called a controller.

The teaching box 24 used in the present invention has a liquid crystal monitor and an operation unit for operating the displacement of the emission optical system 10 or the work table 65, and is connected to the main control unit 69 by wire or wirelessly. The operator holds the teaching box 24 for teaching, operates the operation unit while watching the monitor 69-2, and operates the CC.
The emitting optical system 10 or the work table 65 is moved by a predetermined distance such that the center point of the image of the D camera 13 is along the line to be processed. Strictly speaking, the operator only needs to operate the emitting optical system 10 or the work table 65 by a predetermined distance so that the line to be processed does not come out of the field of view of the CCD camera 13. The emission optical system 10
Alternatively, the movement distance of the work table 65 need not always be constant.

In the present invention as well, the optical axis of the laser beam B1 and the H axis are set by activating the above-described auto-normal function and auto-focus function each time a predetermined distance is moved.
The optical axis of the e-Ne beam B2 becomes perpendicular to the surface of the work piece 20, and the focal point coincides with the processing point. When the operator moves the exit optical system 10 or the work table 65 by a predetermined distance and then activates the image processing device 21, the image processing device 21 detects the processing line to be described later so that the center point of the image of the CCD camera 13 is the processed line. The operation of aligning to the closest point of is performed. As a result, the control unit 23 finely adjusts the emission optical system 10 or the work table 65 so that the center point of the image of the CCD camera 13 is aligned with the line to be processed.

In any case, the exit optical system 1 according to the teaching
0 or the position data of the work table 65 is determined by the detected machining line, and this position data is determined by the control unit 23.
It is stored in the internal storage unit. Then, in the subsequent actual laser welding, the control unit 23 controls the emitting optical system 10 or the work table 6 based on the position data stored in the storage unit.
Move 5

As can be understood from the above description, in the teaching method of the present embodiment, the output optical system 10 is moved by a predetermined distance on the work by the operator's operation, and the image processing is performed at each time. According to this method, position correction control is performed based on the result, and the corrected position data is stored.

The flow of the machining line detecting operation will be described with reference to FIG. In step S1, after the rough alignment by the He-Ne beam B2 as described in FIG. 11, the CCD camera 13 captures an image of the region including the line to be processed. In step S2, the analog image signal from the CCD camera 13 is converted into a digital signal and taken into the image processing device 21. Image processing device 2
In step 1, first, the digital signal is preprocessed in step S3. Here, as preprocessing, line enhancement and noise removal processing are performed by making the best use of the characteristics of the processed line. Next, the process shifts to step S4 and binarization processing is performed. This 2
The binarization process is a process in which a certain brightness is used as a threshold value, pixels having brightness higher than that are white, and pixels below the threshold value are blackened to obtain a black and white image. As shown in FIG. The portion to be processed L1 to be processed is displayed in black (hatched area).

In step S5, the image processing device 21
The processing line is detected for the black portion after the binarization process, and the processing line is determined in step S6. In order to perform such line detection, in the present embodiment, a straight line detection algorithm called “Hough transform process” described later is adopted. The detected machining line on the work 20 is CCD in the arithmetic unit 22.
The deviation from the center point of the image of the camera 13, that is, the position of the optical axis of the laser beam is calculated. Then, based on this shift amount, a movement amount for moving the center point of the image of the CCD camera 13 to the next processing position on the detected processing line is calculated and sent to the control unit 23 as processing point coordinates.

In FIG. 5, the machining line detected from the starting point to the end point of the machining line L1 is shown here as a straight line overlapping the machining line L1. In this manner, the control unit 23 causes the exit optical system 10 or the work table 65 to be based on the correction processing point coordinates sent from the arithmetic unit 22 each time image processing is performed.
By controlling each drive unit for moving the laser beam, the emitting optical system 10 or the work table 65 is moved so that the focus of the laser beam for processing moves on the detected processing line.
Can be moved. After the movement, the operator causes the storage device to store the position data of the emission optical system 10 or the work table 65 by performing a designation operation for acquiring the position data from the teaching box 24. In this way, the operator moves the emission optical system 10 or the work table by a predetermined distance so that the portion to be processed L1 does not deviate from the image of the CCD camera 13 at the time of teaching, and each time the operator starts the image processing and the position data. It is only necessary to perform the designation operation of capturing the image, and the precise alignment operation for matching the center point of the image of the CCD camera 13 with the line L1 to be processed is unnecessary.

Next, the principle of the processing line detection algorithm by the Hough transform will be briefly described with reference to FIGS. 6 and 7. The XY plane of FIG. 6 is the coordinate system of the photographed image, and (x, y) coordinates are given to each pixel. A straight line group passing through a pixel of a certain coordinate (x _i , y _i ) is expressed by the following mathematical expression 1 as ρ = x _i cos θ + y _i sin θ. Where ρ and θ are the distance and angle from the origin to the straight line. When Equation 1 is considered as an equation relating to ρ and θ, and its locus is drawn in the θ-ρ space, it becomes as shown in FIG. 7. Such a locus is called a Hough curve. The processed line L1 is a pixel with low luminance (called a feature point) in the image, but this mapping is performed for all of them in the image and drawn in the θ-ρ space. In the θ-ρ plane, (a, b) of FIG. 6 is a curve of ρ = acoaθ + bsinθ. The points where many Hough curves intersect indicate that many feature points are on the same straight line. θ−
When a point on the Hough curve in the ρ space with a large number of intersections is (ρ ₀ , θ ₀ ), a straight line ρ ₀ defined by the following equation 2 using (ρ ₀ , θ ₀ ). = Xcos θ ₀ + ysin θ ₀ Equation 2 can be regarded as existing in the image. A straight line is detected using this principle.

FIG. 7 is a θ-ρ plane image subjected to the Hough transform, and FIG. 5 shows the highest point in the θ-ρ plane represented by the straight line of Equation 2 and superposed on the image of the CCD camera 13. ,
This line is displayed in another color, for example yellow.

The above description is for welding. In this case, the straight line can be detected by the presence of the welding line as the processed line portion. On the other hand, in the case of cutting,
By drawing a cutting line as a work line on the portion of the work to be cut by scribing or the like, the cutting line can be detected and automatic alignment can be performed by the same process.

[Embodiment 2] In the laser processing apparatus according to the present invention, the image processing unit performs line detection in addition to the Hough transform processing method described in Embodiment 1 as the predetermined line detection processing. A line detection processing method such as a tracking processing method, a projection processing method, or a least squares method processing method may be adopted. In the second embodiment of the present invention, each of these line detection processing methods will be described.

Even when these line detection processing methods such as line tracking processing, projection processing, least square method processing, etc. are adopted, the first half flow of the processed line detection operation is the same as that of the Hough transform processing method. That is, in any of the line detection processing methods described below, the first embodiment shown in FIG.
Steps S1 to S4 of the processing line detection operation flow
Perform the same process as.

(1) Line Tracking Processing Method In the line tracking processing method, first, a differential image is created in preprocessing. Then, lines are extracted by successively connecting the pixels having a high differential value in the differential image.

For example, as shown in FIG. 9, when the tracking has proceeded from the point A to the point B, the next line candidate is the point C,
There are D and E. Therefore, an evaluation function for the magnitude of the differential value and the pixel connection is set in advance, and the most suitable pixel is selected as the next candidate from the above three points using this evaluation function. By repeating this process one by one,
I can find the line.

As the evaluation function, the sum or average of the differential values and the curvatures along the row of pixels is used. That is, if the sum of differential values is as large as possible and the curvature is small (smooth), the evaluation function value is made large.

(2) Projection Processing Method In the projection processing method, first, the welding line is emphasized to create an image from which noise is removed. Projection is performed on this image from all directions at predetermined intervals. To take a projection means to decide the direction,
That is, the luminance values of the pixels in the image are summed along the direction. For example, the weld line is black and its brightness value is 0 (see FIG. 10).

Then, from all the projection data, the one having the lowest minimum luminance value accumulation value is selected. As a result, it is found that the line passes the position coordinate of the lowest value due to the inclination in the direction of the selected projection data, and the line can be obtained.

(3) Least-squares method processing method The least-squares method processing method prepares an image in which binarization and noise removal are performed in the pre-processing, and the black image of the welding line is the target and the line is obtained by the least-squares method. This is a method of calculating the equation.

The description of the second embodiment is also for the case of welding, and the straight line can be detected by the presence of the welding line as the line to be processed. On the other hand, also in the case of cutting processing, by drawing a cutting line as a line to be processed on the portion of the workpiece to be cut by scribing or the like, it is possible to detect the cutting line by the same process and perform automatic alignment. .

[0040]

As described above, in the laser processing apparatus according to the present invention, when teaching, the operator sets the emitting optical system along the line to be processed so that the line to be processed on the workpiece does not deviate from the field of view of the CCD camera. Just move it,
The image processing device detects a machining line, and the control unit moves the emission optical system or the work table so that the reference point set in the CCD camera coincides with this machining line. Volume and time are also significantly reduced. Moreover, the processed wire of 0.1 mm or less is 0.1 m.
It can be detected with accuracy within m. Further, in the present invention, if a straight line detection algorithm by Hough transform is used as the line detection processing, it is possible to detect even if the line to be processed is interrupted or partially hidden.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an internal structure of an emission optical system in a laser processing apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration necessary for detecting a processed line in the present invention.

FIG. 3 is a flow chart diagram for explaining the operation of the configuration shown in FIG.

4 is a diagram showing a binarized image of a processed line portion obtained by the image processing apparatus shown in FIG.

FIG. 5 is a diagram showing an example in which detected processing lines are overlapped and displayed on the image shown in FIG.

FIG. 6 is an XY plan view for explaining the principle of Hough transform according to the first embodiment of the present invention.

FIG. 7 is a θ-ρ plan view for explaining the principle of Hough transform.

FIG. 8 is a perspective view showing a schematic configuration of a laser processing apparatus to which the present invention is applied.

FIG. 9 is a diagram for explaining the principle of the line tracking processing method according to the second embodiment of the present invention.

FIG. 10 is a diagram for explaining the principle of the projection processing system according to the second embodiment of the present invention.

FIG. 11 is a diagram for explaining the rough alignment of the emission optical system according to the conventional teaching.

FIG. 12 is a diagram for explaining precise alignment of the emission optical system according to the conventional teaching.

FIG. 13 is a diagram for explaining focusing of a laser beam of an emission optical system according to the conventional teaching.

FIG. 14 is a diagram for explaining optical axis alignment of a laser beam of an emission optical system in the conventional teaching.

[Explanation of symbols]

 10 Emitting Optical System 11 Mirror 12 Processing Lens 13 CCD Camera 14 Observation Lens 20 Work L1 Processed Line

Claims (3)

[Claims] 1. Laser processing by moving at least one of the emission optical system and a work table on which the work is mounted so that the optical axis of the laser beam emitted from the emission optical system moves along the line to be processed of the work. In the laser processing apparatus for performing the above, a CCD camera for photographing an area of a predetermined range of the workpiece including the line to be processed is provided in the emission optical system, and the CCD is accompanied by movement of the emission optical system or the work table. An image processing unit for performing a predetermined line detection process on an image including the processed line from the camera to detect a processed line that overlaps the processed line, and an image processing unit in an image of the CCD camera. A positional deviation between a reference point that is set in advance and serves as the optical axis of the laser beam and the closest point on the detected machining line is detected, and this positional deviation is detected. And a controller for controlling the drive unit of the output table to correct the output optical system or the work table, and the resulting position data of the output optical system or the work table is used as teaching data for automatic laser beam processing. A laser processing device that performs welding and cutting. 2. The laser processing apparatus according to claim 1, wherein the image processing unit includes, as the predetermined line detection process, a Hough transform process, a line tracking process, a projection process, and a least squares method process. A laser processing apparatus, wherein the processing line is detected by performing any of the above. 3. The laser processing apparatus according to claim 1, wherein the controller calculates a positional deviation between the reference point and the closest point on the detected machining line and corrects the positional deviation. A laser comprising: a computing device that outputs the position to be moved to in the form of processing point coordinates and outputs it; and a control unit that controls the emitting optical system or the drive unit of the work table based on the processing point coordinates. Processing equipment.