JP2003094186A - Laser beam machining apparatus and laser beam machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for laser beam machining where an output value of a pulse-oscillated laser beam is accurately obtained and the value is reflected to the laser beam machining so that the thickness of a remaining wall part can be stabilized. SOLUTION: A machined hole 12a is formed in a work 12 by a pulse oscillated laser beam. Namely, on outputting of an ON signal from a control device to a laser beam oscillator, the oscillator oscillates a continuous pulse-state laser beam, which oscillates according to a reference pulse, with a large output. On outputting of a switch signal, the pulse-oscillated laser beam with the large output is switched to a laser beam with a small output having a prescribed ratio to the large output. On outputting of an OFF signal, the output of the laser beam with the small output is stopped. The output of the large output laser beam is detected by a detector and calculated by an adding machine in the control device. Based on more or less of the calculated output, the output of the small output laser beam following the output of the large output laser beam is determined and thus the remaining wall part t that has a prescribed thickness is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser processing apparatus and a laser processing method for performing a cleavage process on a work made of, for example, an instrument panel of an automobile with a laser beam.

[0002]

2. Description of the Related Art Generally, an airbag for a passenger seat of an automobile is arranged inside an instrument panel of a dashboard. Then, an opening is formed in the instrument panel so as to face the airbag,
A lid plate is attached to the opening. Alternatively, although the opening is not provided, a groove portion for tearing a predetermined shape is formed in the instrument panel so as to form the opening portion. The airbag is usually covered with the lid plate or the opening portion, and when the airbag is operated, the lid plate is scattered or the opening portion is cleaved from the groove portion, so that the airbag is mounted on the instrument panel. It is designed to bulge from the inside to the outside.

However, in the above-described airbag covering structure, there is a problem that the outer appearance of the lid plate and the groove portion of the open portion appear on the surface of the instrument panel, resulting in a poor appearance. In addition, since the outer shape of the cover plate and the groove of the open portion are reflected in the front window, there is a problem that it is difficult to drive.

In order to deal with these problems, there is also proposed a method in which blind holes are formed on the back surface of the instrument panel and the holes are arranged at predetermined intervals to form cleavages. ing. In this processing method, it is necessary to secure a residual thickness part having a constant thickness between the inner bottom part of the perforation and the surface side of the panel, and to form the fracture strength of the cleavage part to be a predetermined value over the entire circumference. There is.

In order to stabilize the thickness of the residual portion,
It is necessary to stabilize the output of laser light. However, in order to achieve this stabilization, it is necessary that various elements or conditions such as the supply voltage to the oscillator of the laser processing apparatus, the cooling water temperature of the optical system, and the ambient temperature of the processing apparatus are constant. In reality, these factors and conditions are rarely maintained constant, and most of the time, the actual output of the laser light changes due to the change with time of the optical system.

When the laser processing is executed in the state where the output of the laser light changes, the thickness of the residual portion of the work changes, which causes troubles in the tearing of the airbag at the time of inflation and the laser light There is a risk of penetrating the work and leaving small holes or scratches on the work.

[0007]

In order to compensate the changing output of laser light, for example, Japanese Patent Laid-Open No. 63-27868.
The technique described in Japanese Patent No. 7 has been proposed. This technology
As shown in FIG. 9, an output of pulsed laser light according to a reference pulse oscillated at a predetermined fundamental frequency is detected for each pulse, the output is integrated by an integrating circuit, and the integrated value and the reference value are calculated. By comparing, the error between them is determined.

However, when integrating the output of the pulsed laser light, the discharge time in the integration circuit is necessary. However, the pulsed laser light oscillated at a high speed of, for example, 5 KHz has an output OFF time that is too short. It is difficult to secure the discharge time.

For this purpose, it is conceivable to shorten the time constant of the integrating circuit. However, this makes it possible to detect the oscillation noise of the pulsed laser light, as is apparent from the integrated value 30 shown in FIG. On the contrary, if the time constant is made longer, the discharge time of the integrating circuit cannot be secured as described above. Therefore, in the conventional method, a value far from the actual output value is monitored, and the laser output cannot be accurately detected. Therefore, when this conventional method is applied to the cleaving process of the instrument panel, laser output control becomes impossible,
As a result, it is difficult to make the thickness of the remaining portion constant.

The present invention has been made by paying attention to the problems existing in such conventional techniques. It is an object of the present invention to provide a laser processing apparatus and a laser processing method capable of accurately obtaining the output value of laser light by pulse oscillation and stabilizing the thickness of the residual portion.

[0011]

In order to achieve the above object, the invention as set forth in claim 1 is a work thickness detecting means for detecting the thickness of a work in a laser processing apparatus, and the work. Output control means for controlling the output of the laser light so that the laser light at each of the perforation points is irradiated with a large output and then switched to a small output according to the detection result of the thickness detecting means. A laser beam detecting means for detecting the actual output of the laser beam at the time of high power irradiation, an adder for adding the detected outputs, and a high output according to the addition result by the adder. And an adjusting unit for adjusting the output of the laser beam at the time of low power irradiation subsequent to the irradiation so as to match the command value.

Therefore, according to the first aspect of the present invention, it is possible to form a machined hole in which a residual portion is provided on the work by making a hole with the pulsed laser beam.
Then, if the processed holes are continuously formed in a perforated shape along the surface of the work, it is possible to form a groove-shaped cleavage failure. In this case, the perforation with the large-output pulsed laser light is subsequently performed, and the perforation with the small-output pulsed laser light is performed, and the pulse number of the small-output laser light matches the command value according to the laser light output from the large-output laser light Is adjusted. Therefore, even if an error occurs in the depth of perforation by the large output laser light, the error can be eliminated in the perforation by the small output laser light, and the thickness of the remaining portion can be made constant. Further, since the perforation by the small output laser light is performed after the perforation by the large output laser light, the opening side of the processed hole is formed widely. Therefore, the inert gas, the chips of the work, and the like are smoothly discharged, and the highly accurate and efficient drilling work can be performed. Furthermore, in determining the output of the laser light, since the output of each pulse of the pulsed laser light is simply added, the actual output can be accurately calculated. Therefore, the perforation depth, in other words, the thickness of the remaining portion can be accurately ensured based on this accurate output value. Also, by adjusting the output of pulsed laser light according to the thickness of the work, the depth of the machined hole can be adjusted, and the thickness of the remaining part can be kept constant even if the thickness of the work changes. Can be secured.

According to a second aspect of the present invention, in the first aspect, the work thickness detecting means is a capacitance sensor provided at the tip of the nozzle. Therefore, as compared with the case where the laser light transmitted through the work is detected, the work does not have a through hole,
The work thickness can be detected reliably. Further, it is not necessary to provide sensors on both front and back sides of the work, and the structure is simple.

In the invention according to claim 3, in claim 1 or 2, the power of the small output irradiation at the perforation point is 70% or less and 20% or more of the power of the large output irradiation. It is what

Therefore, in the invention according to the third aspect, since the power of the small output irradiation is sufficiently lower than the power of the large output irradiation, the depth of the processed hole is adjusted with high accuracy by the small output laser light. it can.

The invention according to claim 4 relates to a laser processing method, wherein the thickness of a work is detected, and the laser light at each of the perforation points is detected according to the detection result of the thickness of the work. After irradiating with a large output, switch to a small output and irradiate, detect the actual output of the laser light at the time of irradiating a large output, then add the detected outputs and irradiate with a large output according to the addition result. It is characterized in that the laser output of the laser light at the time of irradiation with a small output subsequent to is adjusted so as to match the command value.

Therefore, it is possible to obtain the same effect as that of the first aspect. According to a fifth aspect of the invention, in the fourth or fifth aspect, the output of the high-power laser beam is corrected so that the output matches the command value according to the addition result.

Therefore, since the high-power laser beam having a large drilling depth is to be corrected, the depth of the processed hole can be effectively corrected. According to a sixth aspect of the present invention, in the fourth or fifth aspect, the power of the small output irradiation at the drilling point is 70% or less of the power of the large output irradiation,
It is characterized by making it more than a percentage.

Therefore, in the invention described in claim 6,
It is possible to obtain the same effect as that of the third aspect.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
It will be described with reference to the drawings. As shown in FIG. 1, in the laser processing apparatus of this embodiment, a support member 11 made of a conductor forming a jig is provided on the table 10.
The support member 11 is moved in the X and Y directions by a drive mechanism (not shown). The work 12 is supported and fixed on the upper surface of the support member 11 in a mounted state. In this embodiment, the work 12 is an instrument panel that covers a passenger airbag (not shown) of an automobile as shown in FIG.

The laser head 13 shown in FIG. 1 and FIG.
The support member 11 is driven and controlled by a motor (not shown) so as to be able to move toward and away from the support member 11 and tilt, and a laser irradiation nozzle 14 is projectingly provided at a lower portion thereof. The laser head 13 including the laser irradiation nozzle 14 has a predetermined vertical distance L1 with respect to the support member 11.
The laser irradiation nozzle 14 is relatively moved in the X and Y directions in the state of being set, and is moved to a predetermined punching position on the work 12.

As shown in FIGS. 1 and 2, a laser oscillator 15 is connected to the laser head 13. A plurality of mirrors 21 to 23 and a condenser lens 14a are arranged between the laser oscillator 15 and the laser irradiation nozzle 14.
These form a laser optical path between the laser head 13 and the laser oscillator 15. Each of the mirrors 21
One of 21 to 23 is a half mirror, and a part of the laser light is transmitted through this half mirror. A detection sensor 24 as a laser light detecting means is arranged on the transmitted light path, and the actual output of the laser light by the pulse oscillation oscillated from the oscillator 15 is detected.

The laser oscillator 15 is electrically connected to the controller 16. The control device 16 controls the operation of the entire laser processing apparatus including the laser oscillator 15. A memory 20 is connected to the control device 16, and various data, programs and the like are stored in the memory 20. The control device 16 and the memory 20 constitute a correction unit, an adjustment unit, and an output control unit. Then, the laser light is supplied from the laser oscillator 15 to the laser head 13 under the control of the control device 16 based on the various data and programs stored in the memory 20, and the work 12 is irradiated with the laser light. To be done. Therefore,
This laser beam causes the work 12 to be removed as shown in FIG.
With respect to the machined hole 12 so that the remaining portion t of a predetermined size remains.
a is formed. Then, the laser head 13 and the work W
Based on the relative movement of the above in the X and Y directions, a plurality of the processing holes 12a are continuous along the surface of the work W, and the continuous portions are intermittently formed, so that A perforated split is formed.

That is, as shown in FIG.
6 to the laser oscillator 15 at a fundamental frequency (for example,
A reference pulse of 5 KHz) is output, and an ON signal, an OFF signal, and a switching signal are output. Then, when the ON signal is output, the laser oscillator 15 oscillates continuous pulsed laser light with a large output according to the reference pulse. Next, when the switching signal is output, the oscillated laser light is switched to the small output of a predetermined ratio with respect to the large output laser light. In this embodiment, the small output power is 50% of the large output power. Then, when the off signal is output, the output of the pulsed laser light of low output is stopped. Further, in this embodiment, the number of pulses of the large output laser light and the number of pulses of the small output laser light are preset. However, the number of pulses of each of the large-output laser light and the small-output laser light is set or changed to a different number by the control of the control device 16, as will be apparent from the description below.

The laser light detecting sensor 24 is adapted to detect the output of the high power laser light. Then, the control device 16 calculates the perforation depth for each pulse of the high power laser light based on the detected output of the high power laser light.

On the other hand, the controller 16 includes an adder 25.
Is provided. The adder 25 adds the outputs of the high-power laser light detected by the detection sensor 24, and the added value is stored in the memory 20. Then, the control device 16 adjusts the output timing of the off signal based on the addition result of the outputs from the adder 25. Therefore, the output value of the small output laser light following the output of the large output laser light is corrected by adjusting the output timing of the off signal. In this embodiment, the output value of the small output laser light includes at least one of the pulse frequency of the laser light, the peak power of each pulsed laser light, and the number of pulses.

The base material of the laser irradiation nozzle 14 is formed of an insulating material, the first electrode 17 is formed on the tip thereof, and the second electrode 18 is formed on the outer peripheral surface by coating or the like. A capacitance sensor 19 as a work thickness detecting means is connected to the first electrode 17 and the second electrode 18. During laser processing of the work 12, the capacitance sensor 19 detects the capacitance between the support member 11 and the laser irradiation nozzle 14 according to the thickness of the work 12, and the detection result is sent to the controller 16. Is output.

As is apparent from FIG. 5, the thicker the plate thickness of the work 12, the smaller the detection voltage of the electrostatic capacitance is output. On the basis of this, the control device 16 is controlled by FIG.
The output timing of the switching signal shown in is adjusted. In this embodiment, as will be described later, a depth of approximately 80% of the processed hole is drilled by the high power laser light, and the rest is drilled by the low power laser light. Therefore, work 1
The output of the high power laser light is set according to the plate thickness of 2.
Further, the control device 16 adjusts the output timing of the switching signal in the subsequent perforation based on the perforation amount per pulse of the high-power laser light described above and the value added by the adder 25, The output value of the high output pulsed laser light of is corrected. In this embodiment, the output value of the high-power laser light includes at least one of the pulse frequency of the laser light, the peak power of each pulsed laser light, and the number of pulses.

A thermoelectric power monitor 21 is arranged at one corner of the support member 11. The thermoelectric power monitor 21 receives laser light irradiation before the start of processing or during processing setup and measures the intensity of laser light. Then, the control device 16 receives the detection signal from the thermoelectric power monitor 21 and determines the difference between the command value of the intensity of the laser light and the actual output value of the intensity. Then, based on this determination, the control device 16 adjusts the output level of the laser light for each pulse so that the actual output level of intensity approaches the command value.

Input means 26 such as the input panel shown in FIG.
Is for manually inputting various data and commands. Next, a laser processing method by the operation of the laser processing apparatus of this embodiment configured as described above will be described based on the flowchart of FIG. The flow chart of FIG. 7 proceeds as the program stored in the memory 20 operates under the control of the control device 16.

When the laser processing is started, the laser irradiation nozzle 14 is first lowered to a predetermined programmed position above the work 12 placed and fixed on the supporting member 11 to a predetermined position with respect to the supporting member 11. They are arranged with a vertical gap L1 (step S1). Therefore, the distance between the laser irradiation nozzle 14 and the support member 11 is maintained at a constant value.

In this state, the support member 11 supporting the laser head 13 including the laser irradiation nozzle 14 and the work 12 is provided.
Are relatively moved in the X and Y directions, and laser processing on the work 12 is started (step S2). in this case,
First, in the state where the laser irradiation nozzle 14 corresponds to one punching position on the work 12, the capacitance is detected by the capacitance sensor 19, and the detection voltage according to the plate thickness of the work 12 is input to the control device 16. (Step S3).

Based on the detection result of the electrostatic capacity, the control device 16 sets and corrects the output of the high-power laser light, for example, the number of pulses of the pulsed laser light output (steps S4 and S5). ). At this time, the number of pulses of the small output laser light is predetermined. That is, in these steps S4 and S5, as is apparent from FIG. 4, the thickness of the work piece 12 detected by the capacitance sensor 19 is adjusted so that the thickness of the remaining portion t becomes constant. The number of pulses of high power laser light is set. In this embodiment, the perforation ratio is set in advance as a standard value so that the perforation by the high power laser light is 80% of the thickness and the perforation by the low power laser is 20% of the thickness.

Then, the ON signal shown in FIG. 6 is output from the control device 16, and the high-power pulsed laser light is applied to the drilling position of the work 12 in accordance with the reference pulse number of the fundamental frequency (step S6). , Perforation is started (see FIGS. 4 and 8). At the time of output of this large output laser light, the output (power) is detected by the laser light detection sensor 24 (step S7), and the value of the detected output is added over time by the adder 25, and the addition result shown in FIG. The value 31 is accumulated (step S8).

In this way, when the laser processing with the high-power pulsed laser light by the set pulse oscillation is completed (step S9), the total output value of the actual high-power laser light calculated by the addition by the adder 25 and , A total output value to be obtained by the set laser beam, so to speak, a command value is compared (step S10). As a result of this comparison, if the actual output is insufficient, the command output of the next small output laser beam is increased with respect to the above-described set value, and if it is large, the command output is decreased. (Step S1
1). Here, when both output values are equal, the set value is maintained without being adjusted.

Then, low-power laser processing with the number of pulses set in step S11 is performed (step S12),
When the set number is reached, the boring of the processed hole 12a is completed (step S13). Therefore, when the residual thickness portion t having the specified thickness is formed on the work 12, the perforation by the low power laser light is stopped.

Then, it is judged whether or not there is a subsequent perforation (step S14). If there is no subsequent hole, laser processing is stopped (step S16). The adder 25 uses the time at the end of processing to discharge the accumulated charges as shown in FIG. 8 to prepare for the next addition operation. If there is a subsequent perforation, the perforation depth per pulse of the large output laser light is calculated based on the actual output of the large output laser light measured in step S6 (step S15).

Then, the routine returns to step S3, the thickness of the work 12 is detected by the capacitance sensor 19, and the number of pulses of the high-power laser light is calculated so as to correspond to the thickness. At this time, the number of pulses is calculated based on the perforation depth per pulse calculated in step S15. That is, the pulse number of the large output laser light is calculated and corrected as necessary so that the value obtained by multiplying the perforation depth per pulse by the pulse number is the perforation depth of the large output laser light.

Then, the routines after step S3 described above are executed. Therefore, by repeating this routine, a plurality of machined holes 12a are continuously formed along the surface of the work W, and the continuous portions are intermittently formed, and as shown in FIG. A shaped cleavage 1 can be provided.

Therefore, according to this embodiment, the following effects can be obtained. -The laser beam output correction was performed during high power irradiation followed by low power irradiation. Therefore, even if an error occurs in the perforation depth due to the large output laser light, the error can be eliminated in the perforation due to the small output laser light. Therefore, the remaining thickness part t having a constant thickness can always be ensured with an accurate remaining thickness. Therefore, it is possible to form the cleavage portion 1 which is surely opened under a predetermined condition.

Since the punching with the large output laser light is performed prior to the punching with the small output laser light, the opening side of the processing hole 12a is formed to be wide. For this reason, the inert gas, the chips of the work, and the like are smoothly discharged from the processed hole 12a during the laser light irradiation, and the highly accurate and efficient drilling work becomes possible.

Since the output of each pulse of the pulsed laser light is added by the adder 25, the total output value of the pulsed laser light can be accurately calculated, unlike the case of integration, and the drilling depth, that is, the remaining amount. The thickness of the meat part can be accurately ensured.

By detecting the thickness of the work 12 and adjusting the output of the laser light according to the change in the thickness, the depth of the machined hole 12 a can be adjusted according to the thickness of the work 12. The thickness of the remaining portion t can be adjusted to be constant.

Since the electrostatic capacity sensor 19 is used to detect the thickness of the work 12, unlike the case where a sensor that detects the laser beam transmitted through the work 12, is used, a through hole is formed in the work. The work thickness can be reliably detected without any gaps. Further, it is not necessary to provide sensors on both front and back surfaces of the work 12, and the structure is simple.

When the laser light is adjusted according to the thickness of the work 12, the large output laser light output is adjusted, so that the pulse number of the laser light having a large weight for the depth of perforation is to be adjusted. . Therefore, it is possible to effectively correct the perforation depth by laser processing.

When adjusting the output of the pulsed laser light according to the addition result of the adder 25, by adjusting the number of the small output laser lights, it becomes possible to finely adjust the drilling depth, and to perform accurate adjustment. It is possible to secure the remaining thickness portion t.

· According to the addition result by the adder 25,
By correcting the output of the pulsed laser beam in the subsequent perforation, the remaining portion t having a constant thickness can be formed even in the subsequent perforation in which various conditions are almost the same. Therefore, it is possible to provide the remaining portion having a uniform thickness as a whole.

(Modification) This embodiment can be modified and embodied as follows. -In the said embodiment, the output of the high power laser beam was detected and the laser output for the subsequent perforation was corrected. On the other hand, the outputs of both the high power laser light and the low power laser light are detected and reflected in the subsequent perforation. In this way, more accurate drilling is possible.

In the above embodiment, the output of the large output laser light is detected and the laser output of the subsequent large output laser light is corrected. On the other hand, correct the output of a small output laser beam. By doing so, it becomes possible to finely adjust the drilling depth.

In the above-described embodiment, the output of the high-power pulsed laser light is reflected by the capacitance detector. On the other hand, it should be configured to reflect the output of the small output pulsed laser light.

In the above-described embodiment, the irradiation power of the small output laser light is 50% of that of the large output laser light. On the other hand, 70% or less, 20
Any value between the percentages and above.

As a detecting means for detecting the thickness of the work 12, a sensor other than the capacitance sensor, for example, a sensor that mechanically detects the work thickness by contacting the upper surface of the work 12 is used. If you do this,
The cost for the detection means can be low.

Applying the present invention to a case other than an instrument panel of an automobile, such as a center cover of a steering wheel, which is to be cleaved. In this case as well, it is possible to obtain the same effects as the above-described embodiment.

[0054]

As described above in detail, in the present invention, in the irradiation of the laser light by the pulse oscillation, the output value of the high power laser light of the preceding stage is accurately acquired, and the subsequent small power is output accordingly. Since the irradiation output of the laser light can be adjusted, the excellent effect that the thickness of the remaining portion can be stabilized is exhibited.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a laser processing apparatus according to an embodiment.

FIG. 2 is a sectional view showing a processed portion in the same processed state.

FIG. 3 is a perspective view showing a laser processing state of a work.

FIG. 4 is an explanatory view showing a processed hole.

FIG. 5 is a diagram showing a relationship between a work thickness and a detection voltage.

FIG. 6 is a diagram showing a signal for driving a pulsed laser beam.

FIG. 7 is a flowchart showing the operation of the laser processing apparatus.

FIG. 8 is a graph showing an added value of high-power laser light.

FIG. 9 is a graph showing an integrated value of laser light in a conventional laser processing apparatus.

[Explanation of symbols]

12 ... Work, 12a ... Machining hole, 13 ... Laser head,
14 ... Laser irradiation nozzle, 15 ... Laser oscillator, 16 ...
Control device constituting output control means, correction means, adjusting means, setting means, 19 ... Capacitance sensor constituting work thickness detecting means, 20 ... Output control means, correcting means, adjusting means, setting means Memory, 24 ... Laser light detecting sensor constituting laser light detecting means, 25 ... Adder, l ...
Cleavage part, t ... Remaining part.

Claims (6)

[Claims] 1. A work is irradiated with a pulsed laser beam from a nozzle to carry out perforation, and a perforation point is provided in a row by relative movement between the nozzle and the work, whereby one surface side of the work is provided. In a laser processing apparatus configured to perform a splitting process with a residual thickness portion, in accordance with the work thickness detection means for detecting the thickness of the work and the detection result by the work thickness detection means, each of the above Output control means for controlling the output of the laser light so that the laser light at the perforation point is irradiated with the high power and then switched to the low power, and the actual output of the laser light during the high power irradiation. Laser beam detecting means for detecting the laser beam, an adder for adding the detected outputs, and a laser beam for the low power irradiation following the high power irradiation depending on the addition result by the adder. Laser processing apparatus is characterized in that an adjusting means for adjusting the output to match the command value. 2. The laser processing apparatus according to claim 1, wherein the work thickness detecting means is a capacitance sensor provided at a tip of the nozzle. 3. The laser processing apparatus according to claim 1, wherein the power of the small output irradiation at the drilling point is 70% or less and 20% or more of the power of the large output irradiation. 4. A workpiece is pierced by irradiating a laser beam from a nozzle, and the piercing points are arranged by relative movement between the nozzle and the workpiece, so that one surface side of the workpiece is provided. In a laser processing method that performs cleavage processing with a residual thickness part, the thickness of the work is detected, and the laser beam at each of the above-mentioned perforation points is irradiated with a large output according to the detection result of the thickness of the work. After switching to small output and irradiating, the actual output of the laser light at the time of high output irradiation is detected, then the detected outputs are added, and the small output following the high output irradiation is added according to the addition result. A laser processing method characterized by adjusting a laser output of a laser beam during irradiation so as to match a command value. 5. The laser processing method according to claim 4, wherein the output of the high-power laser light is corrected so that the output matches the command value according to the addition result. 6. The laser processing method according to claim 4, wherein the power of the small output irradiation at the drilling point is 70% or less and 20% or more of the power of the large output irradiation.