JPH033550B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic teaching method for automatically memorizing processing lines in a laser processing machine that performs processing such as welding and cutting using a laser beam.

[Conventional technology]

In a laser processing machine, the head that projects the laser beam is driven in the three axes of X, Y, and Z, and the head is moved along a processing line that has been artificially memorized in advance to achieve a predetermined position. Machining is performed on the workpiece using the machining line, but the operation of memorizing the machining line is called teaching. Conventionally, the head was moved by a switch in the control box, and this movement trajectory was memorized as the coordinate position. It is designed to be stored sequentially.

[Problem that the invention seeks to solve]

However, when the shape to be machined becomes complex, manual teaching using a switch requires a long time and poses problems such as difficulty in high-precision teaching.

The purpose of the present invention is to fundamentally solve these conventional problems, and the present invention is an extremely effective laser system that allows teaching to be performed automatically by simply marking the machined surface along the process line. This provides an automatic teaching method for processing machines.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention is constructed by the following means.

That is, a marking with a light reflectance different from that of the processed surface is applied to the processed surface of the workpiece along the center of the processed line, and changes in reflected light based on a light spot projected from a light source to the processed surface are detected, and the laser The head that projects the beam is moved along the direction in which the reflected light changes repeatedly, and the coordinate point of the center position where the reflected light changes due to marking occurs is determined, and this coordinate point is sequentially stored in the memory.

[Effect]

The markings are therefore detected optically and
The coordinate points indicating the center position of this are sequentially stored in the memory and become the taught data, so that teaching can be automatically performed simply by marking on the processing line.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to figures showing examples.

FIG. 2 is a cross-sectional view of the head that projects the laser beam. The laser beam 3, which is focused by the processing lens 2 provided inside the outer tube 1, is projected onto the workpiece 4. In addition, on one side of the outer cylinder 1,
A light source 6 such as a semiconductor laser oscillator that generates a laser beam with a wavelength different from that of the laser beam 3 is disposed, and the laser beam from this is transmitted through a projection lens 7 provided on the projection side.
The laser beam 3 is focused on the surface of the workpiece 4 and projected into the vicinity of the laser beam 3 as a light spot 8.

The light spot 8 is reflected on the surface of the workpiece 4 and is reflected by an imaging lens 11 provided on the other side of the outer cylinder 1.
The reflected light enters the PSD as a light receiving element.
[Position Sensitive Detector.] 12 as an image is projected, and from both ends of the PSD 12, currents i _A and i _B corresponding to the incident position of the image-formed light ray are sent out respectively.

Here, the imaging position P on the PSD 12 is
It is determined according to the facing distance l between the processing lens 2 and the workpiece 4, the horizontal distance L between the projecting lens 7 and the photographing lens 11, and the facing distance A between the photographing lens 11 and the workpiece 4. If the current values sent out from the PSD 12 are i _A and i _B , the imaging position P can also be determined by the following equation.

P=i _A −i _B /i _A +i _B …(1) Also, the opposing distance A is the optical axis 9 of the laser beam 3.
It is determined according to the angle Φ between the optical axis of the light spot 8 and the angle θ between the optical axis 13 of the photographing lens 11 and is expressed by the following equation.

A=L・tan(90−φ)/1+tan(90−φ)/tan(9
0−φ)…(2) Therefore, if Φ and θ are constant values, A will be a constant value, and the difference between the facing distance l and the facing distance A will also be constant, so using these as the standard The relationship between the value of the imaging position P and the facing distance l can be expressed by the following equation.

l=K·P (3) [K: constant] That is, the relationship between the value of the imaging device P and the facing distance l is proportional to each other.

If the head is moved parallel to the surface of the workpiece 4 so that the value of this opposing distance l is constant, the light spot 8 will always almost coincide with the projection point of the laser beam 3, and therefore this reflection will be The light always forms an image at an imaging point on the PSD 12, that is, an imaging position P via the photographing lens 11.

In this way, when the laser beam 3 is not projected, the head is moved in parallel while keeping the facing distance l constant, and the light spot 8 is irradiated onto the marking surface made on the processed surface of the workpiece 4, and the reflected light is PSD12 output change, i.e. current value i _A + i _B
By determining this, markings can be detected.

FIG. 3 is a plan view showing the state of detection of markings by the optical spot 8, in which a tape 21 whose light reflectivity for the optical spot 8 is different from that of the processed surface is placed on the processing surface of the workpiece 4 at the center 22 of the processing line. In this example, the long axis direction of the workpiece 4 is aligned with the _X1 - _X2 axis, and this is attached to the processing table of the laser processing machine (not shown in the figure) It is intended to be placed on top.

Therefore, the head can be manually operated to
1, the scanning direction is specified, and the head is automatically controlled to align with the reference point 23 of X ₁ ,
While driving in the X ₂ , Y ₁ , Y ₂ directions, the facing distance l
is kept normal, and the scanning trajectory 24 by the light spot 8 is
As shown by the dotted line, if the head is moved along the direction in which changes in the light reflected by the tape 21 are repeated, one side 25 and the other side 2 of the tape 21
6 and the scanning locus 24 intersect each other, the reflected light changes, and the width W of the tape 21 can be determined from this. When the center of this is calculated, the coordinate point indicating the center 22 of the processing line is found. Required sequentially.

FIG. 4 is a waveform diagram showing how the reflected light changes, that is, the sum of the coordinate point where the light spot 8 is irradiated and the current value sent out from the PSD 12 due to this reflected light _.
It is a diagram showing the relationship with + _iB . Then, as shown as a waveform in this figure, a pulse with a pulse width corresponding to the width W of the tape 21 is generated, which is determined as a numerical value by counting clock pulses, etc.
By multiplying by 2, the center 22 can be found. Accordingly, by calculating based on the coordinate points where the leading and trailing edges of the pulse occur, the coordinate point of the center position that coincides with the center 22 can be found. .

FIG. 5 shows that while processing the output of the PSD 12,
It is a block diagram of a control unit that performs various controls;
Processors such as microprocessors [hereinafter referred to as
Mainly CPU] 31, fixed memory [hereinafter referred to as
ROM] 32, variable memory [hereinafter referred to as RAM] 33,
Interfaces (hereinafter referred to as I/F) 34 to 39 are arranged around the periphery, and these are connected by a bus bar.
The CPU 31 executes instructions stored in the ROM 32 and performs control while accessing predetermined data to the RAM 33.

In addition, PSD1 based on the reflected light of light spot 8
The output currents i _A and i _B from 2 are each connected to a load resistor R
The terminal voltage of this is connected to amplifiers 41A and 41B.
In addition to being amplified with the same gain for each individual,
In response to the control signal from the I/F 35, the analog
The signal is sent to a digital converter (hereinafter referred to as A/D) 43, where it is converted into a digital signal, and then sent to the CPU 31 via the I/F 36.Based on this, the CPU 31 performs the distance measurement described above. A device that performs calculations, sends out a control signal in the direction of keeping the facing distance l at a specified value, and drives the Z-axis motor [hereinafter referred to as M _Z ] via the I/F 39 and drive circuit [hereinafter referred to as DR] 53. It is becoming.

On the other hand, the CPU 31 is connected to the I/F from the operation box 44.
In response to a command via I/F 37, 38 and DR 51, 52, an X-axis motor (hereinafter referred to as _M
4 and the Y-axis motor [hereinafter referred to as M _Y ] 55, the head is moved in the X _{1 -}
In addition to moving in the Y _{1 -} Y ₂ direction, during automatic teaching, _M The scanning control shown in FIG. 12 is performed to obtain each coordinate point of the center 22, which is sequentially stored in the RMA 33, read out during machining, and controlled to automatically move the head.

FIG. 1 is a flowchart showing the control situation during automatic teaching by the CPU 31, and the fourth
“W counter clear” 101 for determining the pulse width W shown in the figure by counting clock pulses;
And store the coordinate point of the found center position
“Address counter ← 0” 102 is executed to specify the address of the RAM 33, and the initial state is set, and the coordinate point of the reference point 23 shown in Fig. 3 is set.
Obtained based on the current control status of M _X 54 and M _Y 55,
After storing by “Reference _X・_Y →RAM _” 103 _, “ _M
and “A/D output change?” 114 is displayed.
If NO, steps 111 and subsequent steps are repeated.

When the light spot 8 deviates from one side 25 of the tape 21 and step 114 becomes YES, the address specification is incremented by the "address counter +1" 121, and the " _MY /reverse direction drive" 122 and " _MZ /correction drive" 123 is performed, the head is moved to the table 21 side, "A/D output change?" 131 becomes YES, and when the light spot 8 reaches one side 25 of the tape 21, this The coordinate point is set by “X・Y→Buffer memory” 132.
The data is stored in the buffer area of the RAM 33, "W counter start" 133 is performed using the W counter, and the head is moved in the same direction using " _MZ /correction drive" 134 while setting the facing distance l to the specified value.

However, while step 131 is NO, CPU3
The timer configured in step 1 monitors the predetermined time "t ₁ elapsed?" 141, and if this is NO, steps 123 and subsequent steps are repeated, but if the timer times up and step 141 becomes YES,
`` <sub>MX</sub> /reverse direction drive'' 142 causes movement in the X <sub>2</sub> direction, opposite to the previous one, and when ``A/D output change?'' 142 becomes YES, the process moves to step 132.

Also, while step 143 is NO, a similar timer monitors "t ₂ elapsed?" 151, and NO
If so, step 123 and subsequent steps are repeated, but if step 151 becomes YES due to time-up,
The head is moved in the _Y1 direction opposite to the previous one by "M _Y /reverse direction drive" 152, and step 123
Repeat the following.

Therefore, even if the head is moved in the _X1 and _Y2 directions by steps 111 and 122,
If tape 21 is not present, steps 142,
152, it changes to the movement in the X ₂ and Y ₂ directions,
A search for tape 21 is performed.

After one side 25 of the tape 21 is detected and steps 132 to 134 are executed, the light spot 8
crosses the tape 21 and reaches the other side 26,
“A/D output change?” 161 becomes YES,
The coordinate point at this time is “X・Y→Buffer memory”
After storing it in the buffer area of RAM 33 by 162 and performing "W count stop" 163,
“W/2 calculation” based on the count value of the W counter
164 and "center coordinate point calculation" 165 are performed, and the coordinate point of the center position obtained thereby is stored in the address specified by the address counter of the RAM 33 by "center X/Y → RAM" 166, After performing "W counter clear" 167, steps 121 and subsequent steps are repeated while "No A/D output?" 191 is NO.

However, in response to NO in step 161, each of "t ₃ elapsed?" 171 to "A/D output change?" 173, "t ₄ elapsed?" 181, and M _Y /reverse direction drive" 182 is answered in the same manner as described above. Steps are provided to correct transverse errors in the tape 21.

Therefore, as shown in FIG. 3, the "M _Y /reverse direction drive" 122, 152, 182 and the " _M 131, 1 "A/D output change?" 131, 1
The head moves in a direction in which the states 43, 161, and 173 become YES repeatedly, and in accordance with the progress of address specification in step 121, the head moves in step 166.
Accordingly, each coordinate point X and Y of the center position that coincides with the center 22 is sequentially stored in the RAM 33.

Further, when the scanning of the tape 21 is completed and the optical spot 8 deviates from the workpiece 4, the process proceeds to step 191.
becomes YES, and the timer says “t ₅ elapsed?”19
2 becomes YES, “M _X , M _Y , M _Z stop”
193 to end automatic teaching.

Therefore, by simply pasting the tape 21 onto the machining line, each coordinate point of the machining line is stored in the RAM 33, and the CPU 31 is activated in response to a command to start machining.
Each coordinate point of the RAM 33 is read out sequentially, _and the _M This results in faster speed and higher precision.

However, a plurality of light sources 6 are used, and the light spots 8 are projected at mutually symmetrical positions near the laser beam 3, and these reflected lights are collectively received by the PSD 12, and based on the average position of each light spot 8. The facing distance l may be measured, and the light source 6
The same applies to the use of light-emitting elements such as lamps and light-emitting diodes, and according to the type of light source,
An optical filter may be provided on the imaging lens 11 side to allow these emission wavelengths to pass and to block emission wavelengths caused by the laser beam 3 and heat generated at the processing point.

Furthermore, instead of using the SPD, a photodiode array or the like may be used, and the same effect can be obtained by selecting the circuits of the resistor R to A/D43 accordingly. Instead of using the CPU 31, various logic circuits and calculation The configuration in Figure 4 can be selected arbitrarily, such as using a combination of circuits, and in Figure 1, steps may be replaced or replaced with equivalent ones, or unnecessary steps may be replaced depending on the situation. Depending on the conditions, the scanning trajectory 24 may be made sinusoidal or rectangular, or the scanning period may be shortened depending on the bending of the tape 21.

Incidentally, instead of pasting the tape 21, the same effect can be applied by marking with paint or the like having a light reflectance different from that of the processed surface.If the color of the marking is different from that of the processed surface, the light reflectance is almost the same. However, the present invention can be modified in various ways, such as making it possible to discriminate using an optical filter.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, teaching of a processing line becomes easy and fast, and high accuracy is achieved, and a remarkable effect can be obtained in a laser processing machine that performs automatic processing.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, and FIG. 1 is a flowchart of the control situation, FIG. 2 is a sectional view of the head, FIG. 3 is a plan view showing the marking detection situation, and FIG.
The figure is a waveform diagram showing changes in reflected light, and FIG. 5 is a block diagram of the control section. DESCRIPTION OF SYMBOLS 1...Outer cylinder, 2...Processing lens, 3...Laser beam, 4...Workpiece, 6...Light source, 7...Light projection lens,
8...Light spot, 11...Imaging lens, 12...
PSD (light receiving element), 21...tape (marking),
22...Center, 23...Reference point, 24...Scanning trajectory, 2
5...One side, 26...Other side, 31...CPU (processor), 32...ROM (fixed memory), 33...RAM
(variable memory), 44...operation box, 54...M _X (X-axis motor), 55...M _Y (Y-axis motor), 56...
M _Z (Z-axis motor).

Claims (1)

[Claims] 1 Perform processing along the taught curved processing line, and measure the facing distance between the head that projects the laser beam and the workpiece by imaging the light spot projected onto the workpiece from the light source. In the laser processing machine, a marking having a light reflectance different from that of the processing surface is applied to the processing surface of the workpiece along the center of the processing line, a change in reflected light due to the light spot is detected by a PSD element, Laser processing characterized in that the head is moved along a direction in which the change in the reflected light repeats, a coordinate point of a central position where the change in the reflected light due to the marking occurs is found, and the coordinate point is sequentially stored in a memory. Automatic teaching method of the machine.