JP2809064B2 - Method and apparatus for controlling laser processing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a laser beam machine.

[0002]

2. Description of the Related Art In general, in laser processing (cutting), parameters of the material and thickness of a material are used as parameters. In the case of continuous laser oscillation, processing conditions such as a processing speed and an assist gas pressure, and in the case of laser pulse oscillation. Defines the processing conditions in which the pulse frequency of the oscillator and the pulse duty (the ratio of the pulse width to the pulse period) are added. The above processing conditions for maintaining high quality processing have regularity in a certain range, but strict conditions have so-called ambiguity, and are often determined by a processing expert (expert). Conventionally, when necessary, processing conditions determined by an expert are stored in a machine as basic data, and processing is performed by referring to the processing conditions uniquely.

In addition, separately from the above, the light emitted from the cut portion having the same wavelength as the laser light and the light having a different wavelength are observed, and it is detected that the intensities of both the emitted lights have simultaneously decreased. A monitoring method of laser cutting in which the cutting is judged to be completed has been proposed (JP-A-4-327392).

[0004]

However, in the above-mentioned conventional method, expert data is required for all workpieces having different types or thicknesses of the processing material, and the versatility is poor. Is not monitored,
It is necessary for the operator to determine whether or not the processing is performed normally. For this reason, the frequency of occurrence of processing defects increases, and unattended processing cannot be performed. In addition, if processing is not performed well, the amount of spatter (molten mass) increases, and scattered spatter adheres to and damages the condensing lens, as well as lowers the condensing performance and promotes processing defects. Cause a vicious cycle of As a result, the expensive condenser lens becomes unusable in a short time, and the processing efficiency is significantly reduced.

[0005] The latter monitoring method is a form of control and can be evaluated for monitoring the cut portion. However, it is only possible to know the completion of cutting, and the unmanned operation is performed by reducing machining defects. It is not possible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for controlling a laser beam machine which reduce machining defects and enable unmanned operation.

[0007]

To achieve the above object, according to the Invention The method of controlling a laser machining apparatus according to claim 1, wherein the processing
Converting means for converting the emitted light of the unit into an electric signal, an amplifier for amplifying the electric signal of the converting means to a value suitable for internal processing, and a parallel connection for extracting signals of different levels from the signal amplified by the amplifier At least two Schmitt trigger circuits, a delay circuit that individually delays the output signals of the respective Schmitt trigger circuits by a required time to form a continuous signal, and an output circuit that individually outputs the output signals of the respective delay circuits. The light emitted from the processing unit is introduced into the light detection unit having a signal, and a signal is output from each of the output circuits. An ON time equal to or longer than the trigger level of one Schmitt trigger circuit and another Schmitt trigger corresponding to the ON time The ratio of the ON time equal to or higher than the trigger level of the circuit is measured and compared with the storage content stored in the storage unit in advance by the comparison unit. Based on the comparison result, the laser processing machine is used. It was configured to modify the processing conditions.

According to a second aspect of the present invention, there is provided a control method, comprising: conversion means for converting light emitted from a processing section into an electric signal; and an amplifier for amplifying the electric signal of the conversion means to a value suitable for internal processing. At least two parallel-connected Schmitt trigger circuits for extracting signals of different levels from the signal amplified by the amplifier, and individually delaying the output signals of the respective Schmitt trigger circuits by a required time to form a continuous signal A Schmitt trigger having a high trigger level is obtained by introducing radiation emitted from the processing unit to a light detection unit having a delay circuit and an output circuit for individually outputting an output signal of each delay circuit to output a signal from each of the output circuits. After the signal of the output circuit of the circuit is turned OFF, the ON time of the Schmitt trigger circuit having a low trigger level is measured and compared with the storage content stored in the storage unit in advance by the comparison unit. And configured to modify the processing conditions of the laser machine based on the compare results.

According to a third aspect of the present invention, there is provided a conversion means for converting the radiated light of the processing unit into an electric signal, an amplifier for amplifying the electric signal of the conversion means to a value suitable for internal processing, and an amplifier amplified by the amplifier. At least two parallel-connected Schmitt trigger circuits for extracting signals of different levels from signals, a delay circuit for individually delaying an output signal of each Schmitt trigger circuit by a required time to form a continuous signal, and each delay circuit Into the light detection unit having an output circuit for individually outputting the output signals, the emitted light of the processing unit is introduced to output a signal from each of the output circuits, and a certain check interval time inversely proportional to the processing speed is determined. In the meantime, the frequency at which the output signal is turned on is checked in order from the output circuit of the Schmitt trigger circuit having a low level, and the stored content previously stored in the storage unit is compared with the comparison unit. Comparison, and configured to modify the processing conditions of the laser machine based on the comparison result.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the modification of the processing condition is performed by changing the laser output
Loose duty, processing speed, assist gas pressure,
The distance includes at least one distance from the processing material of the lens .

Further, the invention of claim 5 provides the invention according to claims 1 to
4. In the invention as described in any one of 4. above,
The correct control rule is a control rule based on fuzzy inference.
There was a certain configuration.

A control device according to a sixth aspect of the present invention includes a light detecting section for converting the radiated light of the processing section into an electric signal, and a storage section for storing, as a standard pattern, the intensity of the radiated light of the processed section during the best processing. A comparison unit that compares the intensity of the radiated light output from the light detection unit with the standard pattern in the storage unit and outputs the comparison result, and controls the laser processing machine based on an output signal of the comparison unit. And a control unit, wherein the light detection unit comprises:
A converting means for converting the radiated light of the processing unit into an electric signal, an amplifier for amplifying the electric signal of the converting means to a value suitable for internal processing, and a parallel for extracting signals of different levels from the signal amplified by the amplifier At least two variable Schmitt trigger circuits connected to each other, a delay circuit having a variable delay time that individually delays the output signal of each Schmitt trigger circuit by a required time to form a continuous signal, and an output of each delay circuit And an output circuit for individually outputting signals.

[0013]

[Function] The light detecting section converts the radiated light of the processing section into an electric signal.
To measure Te. The storage unit previously stores the radiation light of the processed portion of the normal processing which is the best as the standard pattern. Comparing unit, measuring the emitted light measured by the light detection unit at the time of laser processing
The fixed result is compared with the standard pattern, and the result is output to the control unit. The control unit corrects the processing conditions of the laser processing machine according to a predetermined control rule so that the measurement result of the emitted light falls within a predetermined range of the standard pattern. Therefore, good processing can be performed unattended.

For modifying the processing conditions, one or more of a laser output pulse duty, a processing speed, an assist gas pressure, and a distance from a processing material of the condenser lens are usually used.

If the control rule is fuzzy inference, the laser processing machine can be controlled more finely.

[0016]

1 to 3 show an embodiment of a control device for a laser beam machine according to the present invention. The control device includes a light detection unit (device) 1, a storage unit 2, a comparison unit 3, and a control unit 4. The light detecting unit 1 converts the radiated light of the processing unit K into an electric signal and measures the intensity of the radiated light.
An optical fiber 6 for receiving the emitted light, a phototransistor (conversion means) 7 for converting the emitted light received by the optical fiber 6 into an electric signal, and amplifying the electric signal of the phototransistor 7 to a value suitable for internal processing. Amplifier 8, a Schmitt trigger circuit 9a, 9b, 9c for extracting a signal of a predetermined level from a signal amplified by the amplifier 8, and an output signal of each of the Schmitt trigger circuits 9a, 9b, 9c is individually delayed by a required time. Integrator circuit to make continuous signal
Delay circuit 1 composed of monostable multivibrator
0a, 10b, 10c and the respective delay circuits 10a, 10b,
The output signal of 10c is converted to signals OUTa, OUTb, and OUTc.
Output circuits 11a, 11b, 11c that output individually as
Mainly.

In the laser processing, as is well known, a laser beam B oscillated from a laser oscillator 12 is applied to a beam protection cylinder 1.
3 through a condenser lens 14 and an assist gas supply port 15
The processing material W is irradiated by irradiating the processing material W from the nozzle 16 together with the assist gas supplied from. The optical fiber 6 captures the light of the processing portion K that has passed through the condenser lens 14 at a position that does not interfere with the laser beam B being processed, and guides the light to the phototransistor 7.

As the phototransistor 7, one having high sensitivity to red light (having a wavelength of about 600 to 800 nm) out of visible light is usually used. Each of the Schmitt trigger circuits 9a, 9b, 9c is provided with a respective volume SLa, SL
b, SLc, the signal level to be detected can be arbitrarily preset, and each of the delay circuits 10a, 10c
b, 10c are the respective volumes TDa, TDb, T
Monostable multivibration with integration time adjusted by Dc
The ON time of the data can be adjusted. The output signal TP1 of the amplifier 8 is supplied to a check terminal 18 and the output signals TP2a, TP2a of the respective Schmitt trigger circuits 9a, 9b, 9c.
TP2b, TP2c are check terminals 19a, 19b, 1
9c can be observed individually.

The storage unit 2 stores a standard pattern (standard waveform) of processing light (radiation light) at the time of processing which is determined to be the best, and control information determined by an expert, which is divided according to the content of processing. . The comparison unit 3 compares the signals OUTa, OUTb, and OUTc from the light detection unit 1 with a standard pattern (condition) of the storage unit 2 and outputs a result to the control unit 4 and the storage unit 2. is there.

The control unit 4 receives a signal from the comparison unit 3 and outputs a laser oscillator 12 of a laser processing machine, a processing table 20 on which a processing material W is placed and which moves a product shape or the like according to a command such as a program, an assist gas. A control signal is output to an auxiliary device 21 or the like that supplies the laser beam B. When the oscillation of the laser beam B from the laser oscillator 12 is a pulse oscillation, the pulse duty, the processing speed, the assist gas pressure, or the processing material W of the condenser lens 14 are used. It controls the distance from the camera.

The storage unit 2 is provided with an operation command of the operation program 22. The storage unit 2 receives the output signal of the comparison unit 3 and outputs a correction signal for correcting the control signal output from the control unit 4 to the laser oscillator 12 or the like based on the expert data.

By the way, when piercing for opening a hole through which the laser beam B penetrates at the starting point of laser cutting is started,
Until a hole is formed, the sputter of the processing material W scatters in four directions on the surface of the material in high temperature red by the action of the assist gas, and emits strong light. Further, when a hole penetrates the material, the molten material blows off to the lower surface of the material, so that the emitted light rapidly weakens.
The optical fiber 6 guides the radiated light to the light detector 1, and the light detector 1 detects the intensity of the radiated light.

FIGS. 4 to 6 show electric signals TP1, TP2c, OUT detected when piercing mild steel.
The example of c is shown. In these figures, (a) is the laser output time during the piercing process, (b) is the time during the piercing from the irradiation of the processing material W with the laser beam B to the opening of the hole, and (c) is the processing material. W indicates the laser output time after the hole has penetrated.

The electric signal TP2c shown in FIG. 5 is obtained by setting the level of the Schmitt trigger circuit 9c to about 15V.
ON for more input, OF for lower input
This is when the adjustment is made to be F. Electric signal O
UTc can be used to detect that a hole has been formed in the material W.

The quality of the laser cutting can be known from, for example, the waveform of the electric signal TP1 detected by the light detecting section 1. FIG. 7 is an example of good piercing of mild steel, and FIG. 8 is an example of normal but not good. In both FIGS. 7 and 8, the electric signals TP1, TP2c, and OUTc are drawn together. In both FIGS. 7 and 8, the electric signal OUTa is set when the trigger level of the Schmitt trigger circuit 9a is set to about 22 V, the electric signal OUTb is set when the trigger level of the Schmitt trigger circuit 9b is set to about 18 V, and the electric signal OUTc is set to the Schmitt trigger circuit 9c. Is set to about 15V.

Electrical signal TP for good piercing (FIG. 7)
When observing 1 carefully, the light is strong immediately after the start of piercing, weakens immediately (about 1 second), and thereafter, the light is almost constant. On the other hand, in the case of the electrical signal TP1 of the piercing (FIG. 8) which is normal but not good, the decrease in the light immediately after the start of the piercing is longer than that in FIG. doing. Electric signal T
The waveform of P1 differs depending on the material of the processing material W. It is explained that this is due to the difference in melting point between the components and the difference in viscosity during melting.

In the present invention, the pulse duty, the processing speed, the assist gas pressure, and the condensing lens 14 are determined based on the detection result of the light intensity of the processing section K by the light detection section 1.
Is automatically controlled in accordance with a predetermined control rule. Usually, fuzzy inference is used as the above control rule. Fuzzy inference, which is described in the form of a rule ifA thenB (if case executes the A if B), the A (antecedent
Part) and B (consequent part) will be described with specific examples.

FIG. 7 in which the piercing is performed well and the electric signals OUTa and OUT shown in FIG. 8 which are normal but not good.
Focusing on b, in the case of FIG. 7, the signal OUTa has an ON time Tai of about 1 second. (Condition 1) The ON time Tbi of the signal OUTb is about twice as long as OUTa. (Condition 2) In contrast, in the case of FIG. 8, the signal OUTa has a longer ON time Tai1 than that of FIG. (Condition 3) The ON time Tbi1 of the signal OUTb is about 4 times of the signal OUTa.
It is twice. .. (Condition 4) is obtained.

Therefore, the signal OU of the above (condition 1)
When the Ta ON time Tai is considered to be a good normal time,
As the determination condition A, the ON time Tai1 of the signal OUTa after the start of piercing is longer than (condition 1). (Decision 1) Also, the ON time Tbi1 of the signal OUTb is the ON time of the signal OUTa .
It exceeded about twice the time Tai1 . ... (Judgment 2)

From this, for example, the following control formula can be created. if (condition 3) and (condition 2 is not satisfied, then
<< Reduce the laser output pulse duty >> (Control formula 1)

The width of the target condition controlled (changed) by the control formula 1 is determined empirically. After executing (executing) this control formula, the machining condition can be further checked by the same method as described above, and the conditions can be further changed to converge to the optimum value.

Another example of fuzzy control for piercing will be described. The purpose of the control in this case is that during processing,
It is to finish machining in the shortest time while monitoring and preventing blow-up defects from occurring, and the basic rules of control antecedent, consequent, and inference rules are as follows (working material W is Iron plate).

Basic Rule When processing light stronger than usual is detected, the average value of the input laser power to the material is reduced. If the control of the laser power is not sufficient, the pressure of the assist gas is increased and decreased to check and adjust whether it is within the best section.

The antecedent variable of the fuzzy inference is the light detection unit 1
Are the presence or absence of the output signals OUTa, OUTb, and OUTc, and their correlation. The consequent part is the (frequency) pulse duty of laser pulse oscillation and the assist gas pressure.

The inference rules are as follows based on the following phenomenon facts. 1) As shown in FIG. 8, if the light emission during piercing is not constant but fluctuates gradually or becomes stronger or weaker, the probability of blowing up increases. 2) As shown in FIG. 9, if the light emission at the start moment is strong, the probability of blowing up is high. (Of course, when strong light emission continues, it blows up.) FIG. 9 corresponds to FIGS. 7 and 8. FIG.
The dashed line immediately after the start of piercing is considered to be saturated.

An example of the if then rule for the initial light emission intensity is as follows. i) If the ON time of OUTa is 0 ≦ Tai ≦ 2.
If it is 0 sec (see (i) of FIG. 10), the pulse duty is reduced by (μAi) Tai × 30 (%). However,
(ΜAi) Tai is a fuzzy value μA at the time of Tai
It is the value of i. ii) If the ON time of OUTa is
If 2.0 <Tai <3.0 sec (see (ii) in FIG. 10), the assist gas pressure is set to 90% of the standard.

Iii) Even if the assist gas pressure is lowered, the ON time of OUTa is 2.0 <Tai <3.0 sec.
(See (ii) in FIG. 10) Then, the assist gas pressure is set to 110% of the standard.
iv) If the ON time of OUTa is 3.0 ≦ Tai
(See (iii) in FIG. 10) If (blowing up), an alarm is displayed outside (because other causes such as nozzle deformation are considered) and piercing is stopped.

An example of an if then rule for a light emission change during piercing is as follows. i) If the ON time (Ai) of OUTb after OFF of OUTa is 1.0 sec <(Ai) (see FIG. 11), the pulse duty is reduced by (μBi) Ai × 30%. Where Ai = Tbi−Tai, (μBi) Ai is
This is the value of the fuzzy value μBi determined by the value of Ai. ii) If OUTb is frequently turned off and then turned on again (NA) (see FIG. 12), the assist gas pressure is reduced by (μCi) NAi × 30%. Here, NA is the number of times, and (μCi) NAi is the value of the fuzzy value μCi determined by the value of the number of times NAi.

An example of fuzzy control for cutting after piercing will be described. In this case, the purpose is to increase the processing speed and shorten the processing time while monitoring and preventing gouging and blow-up that the cut surface melts down during processing and becomes jagged, and blow-up does not occur. The basic rule of the antecedent part, the consequent part, and the inference rule of the control is as follows (in this case, too, the processing material W is an iron plate).

Basic Rule The line being processed is divided by a certain distance, that is, a certain check interval time which is inversely proportional to the processing speed is determined, during which the output signals OUTc,
The frequency of turning ON in the order of OUTb and OUTa is checked, and the processing speed or the average irradiation laser output is adjusted according to the frequency.

The antecedent variable of the fuzzy inference is the light detection unit 1
Are the number of times the output signals OUTa, OUTb, and OUTc are turned on at intervals, and the consequent part is the processing speed and the pulse duty.

The inference rule is based on the following phenomenon facts:
Do the following: 1) If there is strong light emission at the start of processing,
High probability of gouging. 2) If the light intensity during processing is not constant and fluctuates (in this case, a notch that forms a streak like a nail on the cut surface is formed), there is a high probability that gouging occurs (FIG. 1).
3). 3) Once gouging occurs, it often follows one after another in a chain reaction. 4) "Gouging" if it is faster than the standard processing speed
In extreme cases, it is not possible to cut (it looks like an injured state).

The if then rule for disconnection is as follows. i) If OUTa, OU during the check interval
OUTc is ON even if Tb is OFF (NBi
Times), set the processing speed to (μsi) NBi ×
10% faster. Here, (μsi) NBi is the value of the fuzzy value μsi with respect to the value of NBi (FIG. 14).

Ii) If O
Even if UTa is OFF, OUTb is ON (of course, OU
If Tc is ON at the same time) (NCi times), the processing speed is increased by (μti) NCi × 15%. Here, (μti) NCi is the value of the fuzzy value μti with respect to the value of NCi (FIG. 15).

Iii) If OUTa is turned on during the check interval (of course, OUTc and OUTb are also turned on at the same time), the processing is temporarily stopped, temporarily stopped, and then reprocessed. At this time, the processing speed is set to 100%, and the assist gas pressure is reduced by 10%. iv) If ii) is executed, and if OUTa is turned on, on the contrary, the processing is temporarily stopped (determined as self-burning), and the processing is returned to the initial condition and the processing is performed again. If the same state is obtained by rework, it is determined that the product is defective, and the process jumps to the next step. The above i) and ii) include fuzzy control. iii) and iv) are merely sequential controls.

In the figure, in the configuration of the light detecting section 1, each of the regulators SLa, SLb, SLc, TDa, TDb, TD
Although c is adjusted by an electric component, it is more general and highly versatile that the writing can be set by a digital method and can be arbitrarily selected and set. Further, for convenience of explanation, the output of the light detection unit 1 is set to OUT.
a, OUTb, and OUTc are used, but finer control is possible by adding a Schmitt trigger circuit.

In the case of laser pulse oscillation, the radiated light of the processing portion K when the piercing is performed normally has a pulse waveform, and when the processing is defective due to the blowing up of spatter, the pulse waveform in the normal state is broken. Become continuous.
The integration times of the delay circuits 10a, 10b, 10c are large.
If the ON time of the force signal is long, the pulse waveform in the normal state will be continuous and the processing failure cannot be identified. However, if the integration time is shortened or eliminated, the processing failure can be identified. It becomes possible.

[0048] Figure 16 illustrates a case where cutting by piercing, laser continuous wave and Then P ₁ → P ₂ → P ₃ at _one point P, and ends the processing at P _3, the processing of this time An example of the NC program for use (main program) is as follows. 1 ° O1000; (program number) 2 ° G90 G92 XO, YO;; (determination of coordinate system by absolute value) 3 ° G26 M12; G00 X-5, YO; (positioning to the processing start point) 5 ° G22; (starting of piercing processing) 6 ° G23 AO; (starting of outer peripheral cutting processing) 7 ° G01 XX; (processing direction) Command) 8 ° X100, Y300 (Processing direction command) 9 ° G25 (Processing end operation command) 10 ° M30 (Program automatic reset) AO is laser continuous oscillation (CW). A1 of 23 is a pulse oscillation (PW).

FIGS. 17 to 19 show examples of the execution flow of the NC program. Note that “1 °”, 〜, and “10 °” written on the right side of the figure are step numbers corresponding to the NC program.

Steps P- (1),
20 and 21 show examples of piercing, monitoring, and fuzzy control flows in P- (3) and P- (4) for reference. Steps marked with * in FIG. 20 do not always correspond to the detailed contents described above.

Further, Step C- (1), FIG.
FIGS. 22 and 2 show examples of the monitoring of the cutting process and the fuzzy control flow in C- (3) and C- (4).
3 is shown. Also in FIG. 22, the steps marked with * do not always match the details described above.

[0052]

As described above, the laser according to the first aspect is described.
According to the control method of the user processing machine, piercing can be performed well.
The effect can be expected. Further, according to claim 2
According to the invention, it is possible to prevent blow-up defects from occurring during processing.
Effect of finishing processing in the shortest time while monitoring and preventing
Can be expected. Further, according to the third aspect of the present invention,
According to the process, the cut surface melts down during the processing and
To prevent gouging and blowing up
Increase the processing speed as much as possible while
The effect of shortening the construction time can be expected.

In addition, the control of the laser processing machine according to claim 6
According to the device, the ON time of a plurality of Schmitt trigger circuits
And the ratio or frequency of ON time are always accurately measured and added.
Good machining can be performed by unattended operation by reducing machining defects.
Has an effect. Moreover, the trigger of the Schmitt trigger circuit
Both the level and the delay time of the delay circuit are variable
Therefore, the light detection part should be the most suitable for the material and thickness of the processing material.
It can be adjusted to a good state and control accuracy can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a control device for a laser beam machine according to the present invention.

FIG. 2 is a sectional view showing a relationship between a condenser lens and an optical fiber and the like.

FIG. 3 is a detailed view of a light detection unit.

FIG. 4 is a diagram illustrating an example of a waveform of an electric signal of piercing amplified by an amplifier.

FIG. 5 is a diagram illustrating an example of a waveform of a piercing electric signal output from a Schmitt trigger circuit.

FIG. 6 is a diagram illustrating an example of an electric signal of piercing output from an output circuit.

FIG. 7 is a diagram showing a correlation between an electric signal of good piercing and output signals from output circuits of three Schmitt trigger circuits with different trigger levels.

FIG. 8 is a diagram showing an interrelationship between an electric signal for piercing which is normal but not good and a cutting process following the piercing, and output signals from output circuits of three Schmitt trigger circuits with different trigger levels.

9 is a diagram showing a correlation between an electric signal amplified by an amplifier and output signals from three Schmitt trigger circuits with different trigger levels, which is different from FIGS. 7 and 8. FIG.

FIG. 10 is a diagram of a membership function in which an ON time of an output signal OUTa for lowering a pulse duty is “long”.

FIG. 11 is a diagram of a membership function in which light emission is lazy and “prolongs”.

FIG. 12 is a diagram of a membership function indicating a degree of ambiguity of “frequently”.

FIG. 13 is a diagram of waveforms in which a normal cut, a cut in which a notch enters, and a gouging occur.

FIG. 14 is a diagram of a membership function of “high possibility” of gouging.

FIG. 15 is a diagram of a membership function of “high possibility” of gouging.

FIG. 16 is a diagram showing a cutting locus of an NC program.

FIG. 17 is a front part of a schematic execution flowchart of the NC program;

FIG. 18 is a middle part of a schematic execution flowchart of the NC program.

FIG. 19 is the latter part of the schematic execution flowchart of the NC program.

FIG. 20 is the first part of the piercing monitoring and fuzzy control flow diagram.

FIG. 21 is the latter part of the piercing monitoring and fuzzy control flow diagram.

FIG. 22 is a front part of a flow chart for monitoring cutting processing and fuzzy control.

FIG. 23 is a rear end of a flow chart for monitoring a cutting process and fuzzy control.

[Explanation of symbols]

 Reference Signs List 1 light detection unit 2 storage unit 3 comparison unit 4 control unit 6 optical fiber 7 phototransistor 8 amplifier 9a Schmitt trigger circuit 9b Schmitt trigger circuit 9c Schmitt trigger circuit 10a delay circuit 10b delay circuit 10c delay circuit 11a output circuit 11b output circuit 11c output Circuit 12 Laser oscillator 13 Laser protection tube 14 Condenser lens 15 Assist gas supply port 16 Nozzle 18 Check terminal 19a Check terminal 19b Check terminal 19c Check terminal 20 Processing table 21 Auxiliary device 22 Operating program

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B23K 26/00

Claims (6)

(57) [Claims] 1. A conversion means for converting radiation light from a processing section into an electric signal, an amplifier for amplifying the electric signal of the conversion means to a value suitable for internal processing, and a level different from the signal amplified by the amplifier. At least two Schmitt trigger circuits connected in parallel to take out the signal of each other, a delay circuit that delays an output signal of each Schmitt trigger circuit individually by a required time to form a continuous signal, and an output signal of each delay circuit. To the light detection unit having an output circuit to output the light emitted from the processing unit and output a signal from each of the output circuits,
ON above the trigger level of one Schmitt trigger circuit
The time and the ratio of the ON time equal to or greater than the trigger level of the other Schmitt trigger circuit to the ON time are measured and compared with the storage content stored in the storage unit in advance by the comparison unit,
A method for controlling a laser processing machine, wherein the processing conditions of the laser processing machine are corrected based on the comparison result. 2. A conversion means for converting the radiated light of the processing section into an electric signal, an amplifier for amplifying the electric signal of the conversion means to a value suitable for internal processing, and different levels from the signal amplified by the amplifier. At least two Schmitt trigger circuits connected in parallel to take out the signal of each other, a delay circuit that delays an output signal of each Schmitt trigger circuit individually by a required time to form a continuous signal, and an output signal of each delay circuit. To the light detection unit having an output circuit to output the light emitted from the processing unit and output a signal from each of the output circuits,
After the signal of the output circuit of the Schmitt trigger circuit with a high trigger level is turned off, the ON time of the Schmitt trigger circuit with a low trigger level is measured and compared with the stored content stored in the storage unit in advance by the comparison unit. A method for controlling a laser processing machine, wherein the processing conditions of the laser processing machine are corrected based on the comparison result. 3. A conversion means for converting the radiated light of the processing section into an electric signal, an amplifier for amplifying the electric signal of the conversion means to a value suitable for internal processing, and different levels from the signal amplified by the amplifier. At least two Schmitt trigger circuits connected in parallel to take out the signal of each other, a delay circuit that delays an output signal of each Schmitt trigger circuit individually by a required time to form a continuous signal, and an output signal of each delay circuit. To the light detection unit having an output circuit to output the light emitted from the processing unit and output a signal from each of the output circuits,
A certain check interval time that is inversely proportional to the processing speed is determined, and during that time, the frequency of the output signal to be turned on is checked in order from the output circuit of the Schmitt trigger circuit having a low level, and the storage content previously stored in the storage unit and the comparison unit are checked. And a processing condition of the laser beam machine is corrected based on the comparison result. 4. The method according to claim 1, wherein the modification of the processing condition includes at least one of a laser output pulse duty, a processing speed, an assist gas pressure, and a distance from the processing material of the condenser lens. A control method for a laser processing machine according to one of the above aspects. 5. The method according to claim 1, wherein the control rule for modifying the processing condition is a control rule based on fuzzy inference. 6. A light detecting section for converting radiation light of the processing section into an electric signal, a storage section for storing the intensity of the radiation light of the processing section at the time of the best processing as a standard pattern, and A comparison unit that compares the intensity of the emitted radiation light with the standard pattern in the storage unit and outputs a comparison result; and a control unit that controls the laser processing machine based on an output signal of the comparison unit. The light detection unit includes: a conversion unit that converts the radiated light of the processing unit into an electric signal; an amplifier that amplifies the electric signal of the conversion unit to a value suitable for internal processing; and a signal amplified by the amplifier. At least two parallel-connected Schmitt trigger circuits for extracting signals of different levels, and a variable delay time for individually delaying the output signal of each Schmitt trigger circuit by a required time to form a continuous signal Road and control unit of the laser processing machine, characterized in that the output signal of each delay circuit and an output circuit which outputs individually.