JPH10249560A - Laser beam machining method and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser beam machining method and an equipment therefor which detects a defective cut during machining and at the same time, changes it to a wall cut machining condition automatically. SOLUTION: A light generating from a machining part in the laser beam machining time is detected with an optical sensor 19, the quantity level of the detected light and the level range of the quantity of light in the well cutting time of a cutting condition data base 31 registered in a controller 15 to control the laser beam machining equipment are compared, when the quantity level of light detected with the above optical sensor is made out of the level range of the quantity of light in the well cutting time, it is judged as a defective cut, and at least, one of cutting condition being matched to a suitable cutting is selected among the cutting condition data base, and it is changed to the selected suitable cutting condition and machining is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a laser processing method and apparatus.

[0002]

2. Description of the Related Art When cutting is performed by a laser beam machine, if cutting conditions are not appropriate, defective cutting will occur. The defective cutting includes a gouging that cannot be completely cut or a so-called burning phenomenon that occurs when the amount of heat is excessive. In the latter burning, the cutting width is larger than a normal cutting, the cut surface becomes irregular, and a large amount of oxidation product called dross adheres to the back surface of the workpiece.

[0003] The generation of the dross described above is not necessarily limited to the burning phenomenon, and often occurs when cutting conditions are not appropriate. Therefore, after the cutting process is completed, it is often the case that the user begins to take out the product and look at the back surface of the product and notice the generation of dross. Many of the products with dross adhered to the back surface are defective products, so the operator has to deal with it by repeating the work of changing the cutting conditions learned through experience, cutting again, and checking the cutting status is the current situation.

[0004]

As described above, in the conventional laser cutting process, it is determined that the product is defective only when the back surface of the product is cut after the cutting is completed. Will change.
Therefore, defective cutting cannot be prevented beforehand. In addition, a post-process for removing dross of the defective cut product that has occurred is required. Further, depending on the state of dross adhesion, even if the dross is removed, the product value may be reduced or the product cannot be used as a product.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to detect a defective cut during processing and, at the same time, automatically change to appropriate cutting processing conditions for obtaining good cutting. To provide a laser processing method and apparatus.

[0006]

According to a first aspect of the present invention, there is provided a laser processing method, wherein light generated from a processing portion during laser processing is detected by an optical sensor, and a light amount level of the detected light and a laser processing apparatus are controlled. Compare the light amount level range at the time of good cutting of the cutting condition database registered in the control device, and when the light amount level detected by the optical sensor is out of the light amount level range at the time of good cutting, determine that the cutting is defective, The gist of the present invention is to select at least one cutting condition suitable for good cutting from the cutting condition database, change the selected good cutting condition, and perform processing.

[0007] Therefore, it is possible to automatically change the cutting processing conditions to appropriate cutting processing conditions for obtaining good cutting while detecting a defective cutting during processing.

According to a second aspect of the present invention, there is provided a laser processing apparatus having a laser oscillator and a laser processing head which can be positioned relative to a workpiece. The light sensor for detecting the light amount level, the light amount level detected by the light sensor is compared with the light amount level range at the time of good cutting of the cutting condition database registered in the control device for controlling the laser processing device. Judging means for judging the quality of the cutting state, and when the judging means judges that the cutting is defective, at least one cutting condition suitable for good cutting is selected from the cutting condition database, and the selected good cutting condition is selected. And a change means for changing the number to the above.

Therefore, similarly to the first aspect of the present invention, it is possible to detect a defective cut during processing and, at the same time, automatically change the cutting processing conditions to appropriate cutting processing conditions capable of obtaining good cutting.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a control system of a laser processing apparatus 1 according to the present invention. FIG.
As shown in the figure, the laser beam LB output from the laser oscillator 3 is applied to the bend mirror 7 of the laser processing head 5.
After being reflected by the laser beam, the light is condensed by the condenser lens 9 and irradiated to the processing portion of the workpiece W, and assist gas is jetted onto the workpiece W from the nozzle 11 provided at the lower end of the laser processing head 5. It is supposed to be.

A workpiece W is placed on a processing table 13.
A servo motor (not shown) is driven to move and position the workpiece W to a desired position (X, Y) by a positioning command signal 17 from a control device (CNC) 15 for controlling the whole. . Note that the movement positioning with respect to the workpiece W is relative, and the processing table 13 on which the workpiece W is mounted is fixed, and the laser processing head 5 is driven by a positioning command signal 17 of the controller (CNC) 15. Under the desired position (X,
The movement and positioning may be performed in Y).

The condenser lens 9 of the laser processing head 5
An optical sensor 19 for catching light from the workpiece W is provided at an oblique position above. The optical sensor 19 may have any configuration such that an electrical signal output such as a voltage or a current is output in proportion to the detected light intensity, that is, a light amount. For example, a photodiode, a phototransistor,
A CCD or the like can be used. In addition, the installation position of this optical sensor should just be installed in the position which can catch the light from a laser processing part, and is not limited above the condenser lens 9. For example, an optical sensor 19 'may be provided at a side position of the laser processing head 5.

The control unit (CNC) 15 sends an output command signal 23 to a power supply 21 of the laser oscillator 3.
Thus, the output of the laser oscillator 3 can be controlled.

The light captured by the optical sensor 19 is converted into an electrical signal output 25 such as a voltage or current proportional to the intensity of the light, ie, proportional to the amount of light, and the signal output 25 is amplified by an amplifier 27. , And the A / D converter 29
Is converted into a digital signal by the controller (CNC) 1
5 is input.

A database relating to laser cutting conditions is stored and registered in a storage device (not shown) of the control device (CNC) 15. The contents of the laser cutting condition database 31 include, for example, the cutting speed (mm / mi).
n), laser power (W), assist gas pressure (MP
a), the light amount level (V) of the light from the processing section, and the like.

FIG. 2 shows a state where the workpiece W is cut by the laser processing apparatus 1 as described above. This processing example is a state where a large amount of dross (oxidation product) 35 adheres to the vicinity of the cutting groove 33 on the back surface of the workpiece W, which is a typical defective cutting.

In the above-described defective cutting, the molten spatter 37 does not efficiently scatter from the cut processing portion, and becomes a dross (oxidation product) 35 in the cutting groove 33 on the back surface of the workpiece.
Adheres on both sides near. In addition, dross (oxidation product) 3
In the case of defective cutting, such as the case where adhesion occurs, the melt spatter 3 generated on the back surface of the workpiece is smaller than that in the case of good cutting.
7, the light amount detected by the optical sensor changes to the level (V) at the time of good cutting as shown in the graph of FIG.
For g), there are cases of high and low cases. Experiments have shown that the amount of the molten spatter 37 during good cutting is always constant under the same cutting conditions.

Therefore, the light from the processed part is detected by the optical sensor 19 during the cutting process, and the detected light amount level and the light amount level range at the time of good cutting registered in the laser cutting condition database 31 are determined. When the detected light amount level is out of the light amount level range at the time of the good cutting as compared with the control device 15, the control device 1
In 5 it is determined that the cutting is defective.

When the controller 15 determines that the cutting is defective, one of the good cutting conditions registered in the cutting condition database 31 is selected as a new cutting condition, and the selected cutting condition is changed. And continue cutting. If the selected cutting condition results in a defective cut, the next good cutting condition is selected and cutting is performed.

Therefore, according to the above-described method, if a defective cut is detected during the cutting process, a cutting condition that provides good cutting is selected from the cutting condition database, and the cutting condition is changed to the new cutting condition. Since the processing is performed, defective cutting can be prevented. Further, even when the light amount level detected by the optical sensor is on the boundary line of the good cutting condition range in the cutting condition database 31, if the cutting condition is changed to the good cutting condition, the defective cutting in which dross occurs can be prevented. It is also possible to prevent it before it happens.

FIG. 4 shows the frequency band of light emitted by a sputter generated at the time of cutting processing, when the cutting is good (dross-free).
And the time of defective cutting (dross adhesion).
The frequency band at the time of good disconnection in FIG.
It can be seen that it has moved to a higher frequency band than the frequency band at the time of defective cutting.

Therefore, this frequency band is registered in the above-mentioned cutting condition database 31, so that it is possible to determine the defective cutting in the same manner as described above and to prevent the defective cutting from occurring. It is also possible to use the difference in the amplitude of the light from the processed part at the time of good cutting (dross-free) and at the time of poor cutting (dross adhesion). The present invention is not limited to laser processing alone, but can be applied to gas fusing, plasma cutting, and the like.

[0023]

According to the first or second aspect of the present invention, it is possible to automatically change a cutting condition to an appropriate cutting condition for obtaining a good cut while detecting a defective cut during the process. Can be. Therefore, after the cutting process is completed, the product is removed, and then a cutting defect is discovered for the first time,
The conventional problem of coping with defective cutting by repetition of the operation of changing the cutting processing conditions learned based on the experience of the operator and performing cutting again and checking the cutting status again has been solved, and the working efficiency has been greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a control system of a laser processing apparatus according to the present invention.

FIG. 2 is a view for explaining a defective cutting processing state by the laser processing apparatus of FIG. 1;

FIG. 3 is a graph showing a change in the amount of light generated at a cutting portion during good cutting and bad cutting.

FIG. 4 is a diagram comparing a frequency band of light emitted by a sputter generated at the time of cutting processing between a good cut (dross-free) and a bad cut (dross adhesion).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 3 Laser oscillator 5 Laser processing head 7 Bend mirror 9 Condensing lens 11 Nozzle 13 Processing table 15 Control device (CNC) 17 Positioning command signal 19 Optical sensor 21 Power supply device 23 Output command signal 25 Electrical signal output 27 Amplifier 29 A / D converter 31 Laser cutting condition database 33 Cutting groove 35 Dross (oxidation product) 37 Melt spatter

Claims (2)

[Claims] 1. An optical sensor detects light generated from a processing portion during laser processing, and detects a light amount level of the detected light and a cutting condition database registered in a control device for controlling the laser processing device. Comparing with a light amount level range, when the light amount level detected by the optical sensor is out of the light amount level range at the time of the good cutting, it is determined that the cutting is defective, and at least one of the cutting condition databases that is suitable for the good cutting. A laser processing method comprising selecting a cutting condition, changing the selected good cutting condition, and performing processing. 2. A laser processing apparatus comprising a laser oscillator and a laser processing head capable of being positioned relatively to a workpiece, an optical sensor for detecting a light amount level of light generated from a processing portion during laser processing, Judging means for judging the quality of the cutting state by comparing the light amount level detected by the optical sensor with the light amount level range at the time of good cutting of the cutting condition database registered in the control device for controlling the laser processing apparatus. And changing means for selecting at least one cutting condition suitable for good cutting from the cutting condition database when the judgment is that the cutting is defective, and changing to the selected good cutting condition. Laser processing equipment characterized by the following.