JPH0328991B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to correction of a focal position error on an object in a laser processing apparatus that processes an object, such as cloth or leather, by scanning a laser beam. [Prior Art] Generally, as a processing method of a laser processing device, a workpiece supported on a cutting conveyor is irradiated with laser light emitted from a swinging mirror that can swing freely while scanning in two dimensions. A so-called two-axis swinging mirror system is known in which the workpiece is machined by doing this. Part 6 about laser processing equipment using this method
This will be explained with reference to FIGS. As shown in FIGS. 6 and 7, a fabric 100 serving as a workpiece is supported on the upper part, and
Conveyor 102 is a support platform that moves the
A spreading device 104 for the fabric 100 is arranged on the left side. This spreading device 104 has a fabric 10
A raw fabric roll 106 on which 0 is wound is set, and a fabric 1 wound on this raw fabric roll 106 is set.
00 is transferred to the conveyor 102 by the spreading device 104.
It is designed to be sent upwards. conveyor 1
A scrap processing device 108 is arranged on the right side of 02, and is designed to store the remaining scraps after the processing is completed. A substantially U-shaped frame 110 is disposed at an appropriate position near the center of the conveyor 102, and a laser head 112 is fixed approximately at the center of the horizontal portion of the frame 110. This laser head 1
12 includes a first mirror drive section 114, a second mirror drive section 116, and a condensing means 118, each of which is configured, for example, in a zirconia shape. An example of the optical system of laser head 112 is shown in FIG. As shown in this figure, after the beam diameter of the laser beam is expanded through a beam expanding means consisting of a convex mirror 120 and a concave mirror 122 as shown by the dashed line in the figure, the laser beam is incident on a lens 124 which is a condensing means 118. Further, the light is reflected by a mirror 126 and is made incident on the fabric 100. The first mirror drive section 114 includes a mirror 126
, with the axis PX as the center and the arrow FA in Fig. 7 or the 8th arrow
It is driven to swing as indicated by the arrow FB in the figure, and this axis PX coincides with the optical axis (the central axis of the beam of laser light) of the lens 124 of the condensing means 118. The second mirror drive unit 116 is a mirror 126
, with the axis PY as the center and the arrow FC in Figure 7 or the arrow 8
It swings as shown by the arrow FD in the figure. That is, the laser beam RB (see FIG. 6) is focused on the fabric 100 by the convex mirror 120, concave mirror 122, and lens 124, and is focused on the fabric 100 by the first mirror drive unit 114. The fabric 10 is scanned in the coordinate X direction assumed to be
The image is scanned in the Y direction, which is a coordinate assumed to be on 0. Note that the beam expanding means consisting of the convex mirror 120 and the concave mirror 122 is for narrowing down the spot diameter d of the laser beam RB on the fabric 100.
That is, the spot diameter d is expressed as d=kF/D where the focal length F of the lens 124, the beam diameter D of the laser beam incident on the lens 124, and the constant k. Therefore, even when the focal length F is set to a large value, if the spot diameter d is to be kept constant, the beam diameter D must also be increased in proportion to F. In this device, the degree of swing of the mirror 126 can be reduced by increasing the focal length F of the lens 124 and increasing the distance between the laser head 112 and the fabric 100, so such a beam expanding means is included. is preferable. Next, the conveyor 102 or the spreading device 104
A laser oscillator 128 is arranged near the frame 110, and an optical means 13 consisting of a prism, a mirror, etc. is arranged on one shoulder 110A of the frame 110.
0 is fixed in location. A transmission body 132 consisting of a beam duct or the like is provided between the laser oscillator 128 and the optical means 130, and the optical means 1
A similar transmitter 13 is provided between the light collecting means 118 and the light collecting means 118.
4 is provided. That is, the transmission body 132,
134 and optical means 130 to direct the laser light output from the laser oscillator 128 to the laser head 1.
12 is constructed. A processing control device (not shown) is disposed on the side of the conveyor 102 and near the scrap processing device 108, and this processing control device performs production control, pattern making, grading, or marking processing. It consists of a first-stage processing device that performs processing, and a second-stage processing device that performs other direct processing. A data input means such as a paper tape is connected to the preceding processing device. According to the command from this processing control device, the above-mentioned laser oscillator 128, laser head 112,
It controls each device such as the spreading device 104, the conveyor 102, and the scrap processing device 108. Thereby, the fabric 100 is cut by irradiating the fabric 100 with a laser beam emitted from the swingable mirror 126 while drawing a certain pattern on the fabric 100 while scanning the fabric 100 two-dimensionally. That is, first, the fabric spreading device 104 and the conveyor drive device are operated, whereby the fabric 100 is sent out from the raw fabric roll 106 onto the conveyor 102, and when the fabric 100 reaches a predetermined location, the conveyor 102 is stopped. do. On the other hand, the laser oscillator 128 starts oscillating operation according to the operation command,
The laser light reaches the laser head 112 via transmission bodies 132 and 134. The laser beam passes through the beam expanding means and lens 124 described above, and is reflected by a mirror 126 so as to be focused onto the fabric 100. At this time, the first and second
The mirror 1 is moved by the mirror drive units 114 and 116
26 swings around the axes PX and PY, and the laser beam RB is scanned over the fabric 100, which is stopped at a predetermined location, according to a predetermined pattern and marking (see FIG. 6). Further, the lens 124
It moves in the optical axis direction in response to the scanning of RB, and is controlled so that the optical distance between the lens 124 and the fabric 100 is constant. This will give you 100 pieces of dough.
In the focused state, that is, the laser beam
The RB will be cut with the minimum spot diameter. The fabric 100 is cut by the above operations, and then the fabric 100 is sent toward the scrap processing device 108 by the conveyor 102. At this time, the scrap processing device 10
8 is driven. Cut fabric 100A, 10
The OB is collected from the conveyor 102 by the operator and the scraps are stored in the scrap processing device 108. Further, the workpiece may be fabric, leather, etc., as well as metal, plastic, etc. Furthermore, if the workpiece has a relatively small area, it may be placed directly on the conveyor 102. [Problems to be Solved by the Invention] However, in this two-axis swinging mirror type laser processing device, the focal length is determined so that the laser beam is focused on the workpiece.
The position of this focal point is affected by, for example, the dimensional accuracy when manufacturing each part of the device, the assembly accuracy when assembling each part, and the installation accuracy when installing each device, and due to the combination of these accuracy. , it is inevitable that some error in focus position will occur. Among these, errors in the shape of the mirror surface of the two-axis swinging mirror, errors in the perpendicularity between the two axes, errors in the degree of coincidence between one of the two axes and the incident laser beam,
Errors in the parallelism of the above-mentioned one axis, the incident laser beam, and the machined surface, errors in the flatness of the machined surface, etc. cause errors in the focal position, which can reduce the processing accuracy of the workpiece. This often occurs. Of course, in order to reduce each of these errors, we have improved the accuracy of each of the above ~ as much as possible, but there is a natural limit to the improvement of each accuracy, and we do not want to pursue improvements in accuracy unnecessarily. However, there is a problem in that the cost of the laser processing machine increases significantly. This invention was made in order to solve such problems, and even if each of the above-mentioned errors occurs, it is possible to reduce the error in the focal position of the laser beam and improve the machining accuracy of the workpiece. The purpose is to obtain a processing error correction method. [Means for Solving the Problems] A method for correcting processing errors in laser processing according to the present invention is such that a laser beam emitted from a swingable mirror is applied to a workpiece supported on a support base in two dimensions. In a laser processing method that processes a workpiece by scanning and irradiating the workpiece, first, a plurality of reference points are selected on the processing surface of the workpiece, and then the laser beam is irradiated onto the reference points. The error value from the target value is corrected by measuring the error value from the target value in advance by irradiating the sensor, and then correcting the target value using the measured error value. [Operation] In the present invention, since the error value is measured by irradiating a plurality of reference points with laser light in advance, the target value can be corrected using the error value. [Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 5. This invention is based on the fact that there is a limit to the improvement in accuracy of each of the above-mentioned ~, and that the above-mentioned ~
Since there are various errors, after acknowledging the errors in the focus position due to these hardware items,
It is characterized by correcting this focal position error using software. First, the geometrical relationships in the ideal state when there are no errors mentioned above will be described. As shown in Figure 1, the θ ₁ axis (axis PX in Figures 7 and 8)
) and the _θ2 axis (axes in Figures 7 and 8)
Mirror 12 that swings around the axis (axis corresponding to PY)
There are an
26 The 0 point directly below the center is the origin of the X and Y axes. Then, any point X, Y on the processing surface 100S
The values of the rocking angles (θ ₁ , θ ₂ ) about the θ ₁ and θ ₂ axes to irradiate the laser beam RB to are: becomes. That is, in order to draw a figure based on the X and Y coordinate values _of the processing surface 100S, the mirror drive unit ₁₁ is
It is necessary to drive and control 4,116. Next, the error correction method will be described. Machining surface 1
Suppose that when the laser beam RB is irradiated to points X and Y on 00S, the laser beam RB is irradiated to the position (X+ _EX , Y+ _EY ) due to the above-mentioned error. That is, X, Y are target values, E _X ,
E _Y is the X and Y components of the error value. Therefore, _E
Instead of measuring E _Y in advance with some means such as a measuring device and then setting the target value to (X, Y), (X-
If the irradiation point is ( _X , Y-E _Y ), the irradiation point will be (X,
It should be sufficiently close to Y). If the error value resulting from this correction is still not small enough, repeating the same correction as above will reduce the error further. However, in most cases, such repetition is not necessary, and a sufficiently small error can be obtained with one-time correction. If the above error value measurement is performed at several points within the processed surface 100S, the error value at any point can be measured using the interpolation method. Therefore, this interpolation method will be described next. First, we will consider the one-dimensional case and then extend this to two-dimensional cases. As shown in _{Fig . 2} , there are reference points X ₁ , ，
Let E ₂ , ..., E _o (each error value is a value measured by a measuring instrument). If the coordinate of an arbitrary point S on the X axis is X, then in order to find the point X _q just before the point S, let q=X/p be an integer rounded down to the decimal point, then a=X-qp b= Since p-a, the error value E _S at point S is interpolated from E _q and E _q+1 as E _S = E _q + a/p (E _q+1 − _{E q} …(2). Next The above interpolation method is extended to two dimensions.
As shown in the figure, take reference points (mesh points) in a grid pattern on the X and Y planes, and calculate the coordinate values of each mesh point as , n) Let Y(0, 0), ..., Y(0, n), ..., Y(m, n). The X and Y components of the error value at each mesh point are E _X (0, 0), ..., E _X (0, n), ..., E _X (m, n) E _Y (0, 0), ... , E _Y (0, n), ..., E _Y (m, n). The coordinate values of any point S on the X, Y plane are (X,
Y). To find _{the point} immediately before point _S , _{let q} = Y−pq _Y. (X and Y indicate subscripts. The same applies hereinafter.) Here, if we focus on mesh points A, B, C, and D near the arbitrary point S in Fig. 3 and enlarge them, we can see that
It will look like the figure. The index (order of mesh points), coordinate values, and error values of each point A to D are as shown in Table 1.

[Table] Here, in FIGS. 3 and 4, the display of each point A to D is shown as follows as an example. Point A; A (2, 2) Point B; B (3, 2) Point C; C (2, 3) Point D; D (3, 3) By the way, the "simplified notation" for the X and Y components of the error value is ” means that, for example, when focusing on the “X component of the error value” at point A, E _X (q _X , q _Y ) is expressed as E _XA . This display method also applies to the Y component and the A component.
The same applies to all other points (see Table 1). Next, as shown in Figure 4, the length of AB is p,
Let the length of BD be p, and for any point S, a line segment
Let the points on AB and CD be S ₁ and S ₂ respectively, the length of AS ₁ be a _X , and the length of SS ₁ be a _Y. CA and S ₁ S ₂ are parallel. Note that AB and BD may have different lengths, and ABCD may be a rectangle instead of a square. From the values of point A and point B
S When the error value of _one point is interpolated, _{S X} component of the error value of _{one point} = E _S1X = E _{XA + a YA + a _ _ _ _ _ _ p ( E XD − E _ _ _ _} Interpolating the error value of Therefore, the new target value of the S point of the laser beam to be irradiated is (X-E _SE , Y
-E _SY ), the error will be corrected. The above explanation deals with the first quadrant in which X and Y take positive values on the X and Y coordinate planes, but it can easily be expanded to cover the second, third, and fourth quadrants, that is, the entire machining surface. It is clear that it can be done. Also, as an interpolation method, we have explained the linear interpolation method that connects two points with a straight line, but it is clear that interpolation can also be performed using curved interpolation methods such as the quadratic interpolation method that connects two points using a quadratic equation (i.e., a curved line). . Find the error value at any point using equation (3) above, and set the target value as (X-E _SX , Y ) instead of (X, Y).
−E _SY ), and by equation (1), the θ ₁ axis of the laser beam,
Convert into the swing angle (θ ₁ , θ ₂ ) about the θ ₂ axis,
By controlling the drive of the mirror drive units 114 and 116 in this way, corrected irradiation can be performed.
The error in the irradiation position is reduced and the error in the focal position can be corrected. The correction method of the present invention explained above can be summarized as a procedure as shown in FIG. That is, after starting, mesh points are selected on the processing surface 100S (step 1), a reference point at each mesh point is irradiated with a laser beam, and an error value is measured using a measuring device (step 2). Based on this measurement result, the target value of each mesh point is corrected using the method described above (step 3). It is determined whether the error after correction has been sufficiently reduced by this correction (step 4).
If it is still not small enough, use the corrected value instead of the target value for each mesh point (step 5).
Repeat step 2 to step 4. If the error after the above correction becomes sufficiently small (step 4),
The error value at the arbitrary point is determined by the interpolation method described above (step 6), and the target value at the arbitrary point is corrected to become a new target value (step 7). Next, the (X, Y) coordinate values are converted to the (θ ₁ , θ ₂ ) values using equation (1) (step 8), and the mirror drive units 114 and 116 are controlled using the (θ ₁ , θ ₂ ) values. The workpiece 100 is processed by driving and controlling the laser irradiation (step 9), and the method ends when the processing is completed. [Effects of the Invention] In summary, according to the present invention, a plurality of mesh-shaped reference points are selected on a machined surface, a laser beam is irradiated to the reference points, and an error value from a target value is measured in advance with a measuring device. , correct the target value based on this measurement result, and if the error after correction is small enough, use interpolation to find the error value at any point on the machined surface, correct the target value at the arbitrary point, and set a new target. The coordinate value of the arbitrary point described above is converted into the value of the swing angle of the mirror, and the mirror drive section is driven and controlled using the converted value. Therefore, processing error correction can be easily calculated and processed by a computer etc. by simply irradiating laser light, so the processing accuracy of the workpiece can be improved without strict mechanical precision of the processing equipment. can be significantly improved, making it possible to create highly accurate products. In addition, not only can processing error correction be performed continuously, but the laser beam mirror drive unit can be directly controlled, so it can be directly applied to industrial processing equipment using laser beams, and has practical value. will be of high value.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a two-axis swinging mirror system for explaining an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining an interpolation method according to the present invention regarding the X-axis, and FIG. is also an explanatory diagram when the above interpolation method is extended to two dimensions, FIG. 4 is an explanatory diagram that enlarges the part in FIG. 3, FIG. 5 is a flowchart for explaining this invention, and FIG. A seventh perspective view showing the configuration of a laser processing device to which the present invention is applied.
The figure is a simplified front view of the device shown in Figure 6;
This figure is an explanatory diagram showing an example of the configuration of the laser head of the apparatus shown in FIG. 6. 100 is the workpiece (fabric), 100S is the processed surface,
102 is a support stand (conveyor), 126 is a mirror,
RB is a laser beam, S is an arbitrary point, X ₀ , X ₁ ,..., X _q ,
X _q+1 ,…, X _o are reference points, E ₀ , E ₁ ,…, E _q , E _q+1 ,
..., En is the error value. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A workpiece supported on a support table is irradiated with a laser beam emitted from a swingable mirror while scanning the workpiece two-dimensionally. In the laser processing method for processing, multiple mesh-shaped reference points are selected on the processing surface,
The reference point is irradiated with a laser beam, the error value from the target value is measured in advance with a measuring device, the target value is corrected based on this measurement result, and if the error after correction is small enough, the error value on the machined surface is measured. The error value of the arbitrary point is determined by interpolation method, the target value of the arbitrary point is corrected as a new target value, and the coordinate value of the arbitrary point is converted to the value of the rocking angle of the mirror, and the converted value is A method for correcting machining errors in laser machining, characterized in that a mirror drive unit is drive-controlled by: