JPH0422678B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a laser processing method and an apparatus thereof, and relates to a laser processing method and an apparatus thereof, which can produce high quality laser processing with less melting loss due to thermal saturation, even when cutting sheet metal parts with complex shapes at acute angles.
The present invention relates to a method and an apparatus for performing highly accurate laser processing stably and with good reproducibility over a long period of time.

[Conventional technology]

Conventionally, as this type of laser processing apparatus, one having the configuration shown in FIG. 5 (Japanese Patent Laid-Open No. 57-62882) is known. In the figure, 10 is a laser oscillator, 1
2 is a laser beam extracted from the laser oscillator 10, 14 is a reflecting mirror for changing the direction of the laser beam 12, 16 is a lens for focusing the laser beam 12, 20 is a workpiece, and 18 is a workpiece 22 is a motor for moving the table 18, 24 is a motor drive circuit for driving the motor, and 26 is a motor drive circuit control section. 28 is a tachometer generator that detects the rotation of the motor 22, and 30 is an oscillator control device that generates a signal to control the laser output of the laser oscillator 10 based on the speed detected by the tachometer generator 28.

Next, the operation will be explained. First, when a start signal is input to the motor drive circuit control section 26, the motor drive circuit control section 26 and the motor drive circuit 24 start operating and drive the motor 22. Therefore, the speed of the table 18 gradually increases as shown in FIG. 6b, and then moves at a constant speed. The moving speed and moving distance of this table 18 are detected by the tacho generator 28, and the oscillator control device 30
is such that the output of the laser beam 12 output from the laser oscillator 10 is proportional to the moving speed of the table 18, and when the moving speed reaches a certain value, the output of the laser beam is also a constant value as shown in FIG. 6a. control.

When the stop signal is input to the motor drive circuit control section 26, the motor drive circuit control section 26 gradually reduces the moving speed of the table 18 and stops the movement of the table 18, as shown in FIG. 6b. . At this time, the intensity of the laser beam 12 is also controlled to decrease in proportion to the decrease in moving speed.

In this way, the workpiece 20 is controlled so that the amount of light received (the amount of energy received) per unit length is constant, and as shown in FIG. 7, the cutting width 20 and welding width 20a can be kept constant. .

[Problems to be Solved by the Invention] Since the conventional laser processing apparatus is configured as described above, changes in the characteristics of the laser oscillator over time, such as deterioration of the gas in the oscillator, deterioration of the reflecting mirror, etc.
If the input device such as the excitation light source deteriorates, there is a problem in that the expected output of laser light cannot be obtained.

This invention was made to solve the above problems, and it detects the output of the laser beam extracted from the laser oscillator, and determines the optimum laser output corresponding to the processing speed regardless of changes in the characteristics of the laser oscillator. The object of the present invention is to provide a control method and apparatus for a laser processing machine that can always perform stable and optimal laser processing by automatically correcting control inputs so as to obtain the desired results.

[Means for solving problems]

A control method for a laser processing machine according to the present invention moves a workpiece relative to a laser beam generated from a laser oscillator based on a control signal, and processes the workpiece by detecting relative speed. A step of detecting the relative speed of the workpiece and the laser beam by a means, and a step of detecting the relative speed by the relative speed detection means from among pre-stored optimum output value data of the laser oscillator corresponding to the physical properties of the workpiece and the relative speed. A process of determining the optimum output value corresponding to the relative speed, a process of detecting the intensity of the actual laser beam output from the laser oscillator, and a process of comparing the actual laser beam output value and the optimum output value, and determining the deviation. The method is characterized by comprising a step of providing a control signal corrected for the above to the laser oscillator.

Further, the control device for a laser processing machine according to the present invention moves a workpiece relative to a laser beam generated from a laser oscillator based on a control signal, and processes the workpiece. A relative speed detection means that detects the relative speed of the workpiece and the laser beam and outputs a speed signal according to the detected speed, and optimal output value data of the laser oscillator corresponding to the physical properties and relative speed of the workpiece are prepared in advance. an optimum output determining means for determining an optimum output value of the laser oscillator based on the speed signal from the relative speed detecting means and outputting the obtained optimum output value; an output detection means for detecting the output value and outputting the detected output value as an actual laser beam output value; and an output detection means for storing the actual laser beam output value from this output detection means, and and control signal correction means for comparing the output value with the optimum output value from the optimum output determining means and applying a control signal corrected for the deviation to the laser oscillator to control the output of the laser oscillator. .

[Effect]

According to the method and device for controlling a laser processing machine according to the present invention, it is possible to eliminate processing irregularities particularly near the start and end points of processing, and to prevent processing defects due to changes in the laser oscillator over time.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 40 denotes a movable reflecting mirror, and the laser beam 12 is
is inserted into the optical path of the laser output sensor 41 at the appropriate time.
The intensity of the output light is measured by applying reflected light to the control input signal correction section 50, and this data Po is stored in the control input signal correction section 50. 31 is an optimum output determining unit, which determines the optimum output signal Pc of the laser oscillator 10 based on the moving speed of the table 18 detected by the tachometer generator 28.
This is an optimum output determining section that provides the control input signal correcting section 50 with the following.

Reference numeral 60 denotes a system control section, which controls the motor 22 through the motor drive circuit control section 26 and the motor drive circuit 24, and provides program signals to the control input signal correction section 50 and the operating section of the movable reflection strength 40, thereby controlling the entire system. is controlled.

Next, the operation of the optimum output determining section 31 and the like will be described in detail. Workpiece 20 mounted on table 18
is cut by a laser beam focused by a lens 16,
When performing processing such as welding, if the intensity of the laser beam is constant and the relative speed of the workpiece is also constant, then during each process at the beginning, midway, and final stage of the process,
Uneven machining occurs because the energy conditions applied to the workpiece differ. Therefore, the intensity of the laser beam applied to the workpiece is weakened at the initial and final stages when the relative speed of the workpiece is slow, and the intensity of the laser beam is increased during the middle of processing when the relative speed is high.

In other words, the characteristics of the workpiece were taken into consideration, and a laser beam proportional to the relative speed was applied to the workpiece in order to achieve optimal processing conditions. First, data is collected through a preliminary experiment, and this data is stored in the optimum output determining section 31. Note that the method of applying a control signal to the laser oscillator 10 based on the signal indicating the moving speed from the tachometer generator 28 is the same as in the prior art. However, this was successful when the output light of the laser oscillator was stable. However, as the laser oscillator changes over time, its output gradually changes due to factors such as deterioration of the excitation gas, deterioration of the reflector, and fluctuations in pumping input, leading to defects.

Therefore, the output of the laser oscillator 10 is no longer directly controlled by the output of the optimal output determination section 31 as in the conventional method, and a control input signal correction section 50 is provided between the two, and the program of the system control section 60 is Based on this, the value Po of the laser beam 12 measured using the laser output sensor 41 is stored,
By giving the laser oscillator 10 a control signal Pi that corrects the deviation due to the deterioration of the laser oscillator 10, the conventional problems are solved and stable processing with high quality can be continued for a long time.

Figure 2 shows that when the laser oscillator control input Pi and laser output Po are standard, they have a linear relationship A, but
Actually, it is a diagram showing movement from direction B to direction C as time passes.

FIG. 3 shows a movable reflector 40 connected to a laser beam 12.
FIG. 3 is a flowchart of control operations during insertion into the optical path of the device. At first, laser light is output under the initial condition of the size Pi (int). Movable reflector 4
When 0 is inserted, the signal Po is detected and provided to the control input signal correction section 50, and if Po≧Pc(max) is not satisfied (No), correction is performed. If satisfied (Yes), move the movable reflector 40 to the laser beam 12.
This figure shows the process of removing the light from the optical path.

Figure 4 is a diagram showing the relationship between the optimal laser concentration Pc, the laser oscillator control input Pi, and the correction amount △Pi.
=Pc+△Pi.

The present invention is particularly effective when the laser output is controlled at high speed by speed detection, but the same effect can be obtained even when the laser output is not controlled by speed detection. Regarding the type of processing,
It is effective not only for cutting and welding, but also for all laser processing such as surface modification, scribing, and engraving.

Further, in the above embodiment, only the case where the workpiece is moved one-dimensionally has been described, but the present invention is not limited to this, and even when the workpiece is moved multidimensionally, the composite speed or It goes without saying that if the actual speed is detected, the same effect can be achieved, but if applied to objects with two or more dimensions,
It is possible to always control the laser output to the optimum level as the machining speed changes at the bending point during shape machining.

Furthermore, although a case is shown in which a reflecting mirror and an output detection sensor are used as the output detecting means, other laser output detecting means, for example, a pinhole may be provided in the reflecting mirror 14 and the output of the laser beam passing through this pinhole may be detected. Even if such an output detection means is used,
Do the same action.

〔Effect of the invention〕

As described above, according to the present invention, the workpiece and laser beam detected by the relative speed detection means are selected from pre-stored optimal output value data of the laser oscillator corresponding to the physical properties and relative speed of the workpiece. The optimal output value corresponding to the relative speed of light is determined, the determined optimal output value is compared with the actual output value of the laser beam detected by the output detection means, and a control signal corrected for the deviation is given to the laser oscillator. Therefore, even if the laser output changes due to changes in the characteristics of the laser oscillator over time, it does not take much time to detect the change in laser output, and the correction can be made in a short time. This has the effect of allowing stable laser processing with high quality reproducibility.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a control device for a laser processing machine showing an embodiment of the present invention, Fig. 2 is a diagram showing changes in the input/output relationship due to deterioration of the laser oscillator, and Fig. 3 is a sampling of output laser light. Flowchart showing the control operation in the control input correction section when
Figures a and b are diagrams showing the amount of correction when the laser oscillator deteriorates, Figure 5 is a block diagram of a conventional laser output control device using speed detection, and Figures 6 a and b are movement of the workpiece in the conventional device. FIG. 7 is a diagram showing laser light output and moving speed with respect to distance, and a plan view showing an example of processing by a laser processing machine. In the figure, 10 is a laser oscillator, 12 is a laser beam, 14 is a reflecting mirror, 16 is a lens, 18 is a table, 20 is a workpiece, 22 is a motor, 24
26 is a motor drive circuit, 26 is a motor drive circuit control section, 28 is a tachometer generator, 30 is an oscillator control device, 31 is an optimum output determination section, 40 is a movable reflector, 41 is a laser output sensor, and 50 is a control input signal correction section , 60 is a system control unit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. Moving a workpiece relative to a laser beam generated from a laser oscillator based on a control signal,
This method of controlling a laser processing machine that processes a workpiece includes a step of detecting the relative speed between the workpiece and the laser beam using a relative speed detection means, and a process that corresponds to the physical properties and relative speed of the workpiece stored in advance. a step of determining an optimal output value corresponding to the relative speed detected by the relative speed detection means from among the optimal output value data of the laser oscillator; and a step of detecting the intensity of the actual laser beam output from the laser oscillator. A method for controlling a laser processing machine, comprising the steps of: comparing an actual output value of a laser beam with the optimum output value, and providing a control signal corrected for the deviation to a laser oscillator. 2. Moving the workpiece relative to the laser beam generated from the laser oscillator based on the control signal,
A control device for a laser processing machine that processes the workpiece includes a relative speed detection means for detecting the relative speed between the workpiece and the laser beam and outputting a speed signal according to the detected speed; Optimum output value data of the laser oscillator corresponding to the physical properties and relative speed of the workpiece is stored, the optimal output value of the laser oscillator is determined based on the speed signal from the relative speed detection means, and the determined optimal output value is output. output detection means for detecting the intensity of the laser beam output from the laser oscillator and outputting the detected output value as an actual output value of the laser beam; The actual output value of the laser beam is stored, the stored actual output value of the laser beam is compared with the optimum output value from the optimum output determining means, and a control signal with the deviation corrected is given to the laser oscillator. 1. A control device for a laser processing machine, comprising: control signal correction means for controlling the output of a laser oscillator.