JP3222430B2 - Laser processing apparatus and adjustment method - Google Patents

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 for performing cutting, welding, drilling, marking and the like of a workpiece by a laser beam, and a laser focusing point and a laser optical axis position in the laser processing apparatus. The adjustment method.

[0002]

2. Description of the Related Art In a laser processing apparatus that focuses a laser beam and irradiates it onto a work to be processed, and performs cutting, welding, drilling, and marking processing, the position of the focal point (focal point) of the laser beam with respect to the work. This greatly affects the processing performance. Therefore, various methods of adjusting the focal point position have been conventionally proposed.

Normally, in a laser processing apparatus, laser processing is performed by blowing an assist gas together with a laser beam from a hole having an inner diameter of about 0.5 to 8 mm to a processing target position of a workpiece. The assist gas is used for the purpose of isolating the work from the air atmosphere or conversely promoting the oxidation reaction by using oxygen, and the axis of the assist gas jet and the optical axis of the laser beam are used. Good processing is obtained when they match. That is, good processing is obtained when the optical axis of the laser beam and the axis of the hole of the processing nozzle coincide with each other, and if the axis is misaligned, the processing efficiency is reduced.

Therefore, as a method of adjusting the focal point position,
For example, a method in which a plurality of slits are formed on a workpiece while changing the focal point position, a cutting width in each slit processing is measured, and a focal point position in the slit processing with the smallest width is detected as a focus reference position. However, Japanese Patent Application Laid-Open
This is known from US Pat. Also, when the focused laser beam is irradiated on the work, it occurs at the processing point,
Japanese Patent Application Laid-Open No. 6-252485 proposes a method in which light other than laser light returned to a laser oscillator is measured by an optical sensor, and a focus position (a focal point position) is obtained from the output of the optical sensor.

Further, the work is irradiated with a laser beam by changing the position of the condenser lens, the temperature of the laser beam irradiation part is measured, and the focal length (between the condenser lens and the focal point position) is determined based on the measurement result. Is disclosed in JP-A-8-103.
No. 879 proposes this. JP-A-7-16779
In this publication, a laser beam is pulsed to a workpiece while moving a lens, and the energy density of the laser beam at that time is indirectly detected by an optical sensor, a sound sensor, or a vibration sensor. A method for automatically adjusting the focus of laser light according to density is disclosed. Further, Japanese Patent Application Laid-Open No. 7-60468 discloses a method of measuring reflected light of a laser beam applied to a work, and detecting a relative position between a work surface where a lens is focused and a nozzle based on the magnitude of the reflected light. ing.

As a method of aligning the optical axis of the laser beam with the axis of the hole of the processing nozzle, a hole is formed in the processing nozzle by laser light, so that the optical axis of the laser beam and the hole of the processing nozzle are aligned. A method for matching the axes is proposed in Japanese Patent Application Laid-Open No. Hei 10-193151. or,
Japanese Patent Application Laid-Open No. 5-96393 discloses that a processing nozzle is moved by projecting an expansion member from all sides inside a processing nozzle and irradiating a laser beam, thereby expanding the expansion member irradiated with the laser beam. A centering adjustment device that adjusts the optical axis of the laser beam so that the axis of the hole of the processing nozzle coincides is described. JP-A-6-3
No. 28281 discloses a technique in which a voltage is applied between a workpiece having a centered hole and a nozzle, the nozzle is moved back and forth, right and left, and the contact is detected by electrical contact detection means. Position in the center of the hole, then
By driving the condenser lens in the X and Y-axis directions perpendicular to the optical axis direction to make the optical axis of the condenser lens coincide with the center of the hole of the work piece, the optical axis of the condenser lens and the processing nozzle A method of aligning the axes of the holes is described.

In Japanese Utility Model Laid-Open Publication No. Hei 6-65808, a reflector and an optical sensor are provided on the wall of a processing nozzle between a condensing lens and a condensing point, and the optical axis of the laser beam is deviated from the axis of the hole of the processing nozzle. A method is described in which a laser beam is sometimes reflected by a reflector and the reflected light is detected by an optical sensor to detect a deviation between the optical axis of the laser beam and the axis of the hole of the processing nozzle.

[0008]

In the above-mentioned conventional example,
Special means is required as means for detecting the position of the focal point and the optical axis position of the laser beam. It requires means and devices used only for the purpose of detecting the position of the focal point and the position of the optical axis. Therefore, the laser processing device is expensive because the special means is required.

Accordingly, the present invention does not require any special means, and detects the position of the focal point and the position of the optical axis of the laser beam.
It is an object of the present invention to provide a method of adjusting a focal point and an optical axis that can adjust a focal point position with respect to a workpiece and an optical axis position with respect to a processing nozzle, and a laser processing apparatus.

[0010]

SUMMARY OF THE INVENTION The present invention is applied to a laser processing apparatus having a measuring device for measuring a laser output, and utilizes this measuring device for a laser output and reflects a laser beam well. Utilizing the amplification phenomenon due to laser resonance that occurs between the reflection means such as workpieces and test pieces and the rear mirror of the laser oscillator, detection of the focal point position and optical axis position,
Adjustment is performed.

[0011] In the laser processing apparatus, the laser output command, the feedback control so as to hold the command value has been made. For this purpose, a measuring means for measuring the laser output is provided. For example, JP-A-8-1688
As described in JP-A-91, a laser processing device provided with a power sensor for measuring a laser output power inside a laser oscillator and a laser processing device provided with a laser output sensor for measuring a laser output outside a laser oscillator are well known and used. is there. Many of these laser output sensors use a calorimeter type using a thermocouple, and others detect infrared light. In addition, in the case of being provided inside an oscillator, in many cases, a partially reflecting mirror having a transmissivity of about 1% is used as a rear mirror, and the transmitted laser light is converted after detection. In many cases provided outside the laser oscillator, a folding mirror having a transmittance of about 1% or more is used, and a laser output is calculated by detecting the transmitted light. The present invention is applied to a laser processing device using such a laser output sensor (laser output measuring device).

The principle of the method of detecting and adjusting the focal point position and the optical axis position of the present invention using the laser output sensor (laser output measuring device) and utilizing the laser amplification phenomenon described above is as follows. .

The laser oscillator in the laser processing apparatus includes:
Normally, optical amplification is performed between a rear mirror and an output mirror to cause laser oscillation. However, when processing a material that reflects laser light well, the work acts like an output mirror, and the reflected light from the work causes laser resonance between the laser oscillator and the work, causing an unexpectedly large output. There is. This can destroy the laser processing equipment,
This caused unnecessary processing marks on the workpiece. The present invention utilizes a laser oscillation phenomenon which is normally prevented and not used between the work and the rear mirror. In particular, the detection and adjustment of the position of the focal point is performed by utilizing the fact that this laser oscillation phenomenon occurs when the focal point is present near the work surface.

For this purpose, the present invention provides a laser processing apparatus comprising: a measuring device for measuring a laser output; and a distance adjusting means for adjusting a distance between a condensing device and the reflecting means. A reflection unit that reflects a laser beam well is disposed near a point, and the output of the laser oscillator is measured by the measuring device according to a laser output command, so that oscillation is generated between the rear mirror of the laser oscillator and the reflection object. The intensity of the laser output is measured, and based on the measured laser output, the distance between the condensing device and the reflecting means is determined.
Adjust so that the laser output intensity is maximized . In particular,
The laser output is stored in the storage means, the position of the focal point is calculated by the calculating means based on the stored laser output data, and the position of the focal point determined by the calculating means is calculated by the distance adjusting means. The distance between the light collector and the reflection means is adjusted. The adjustment by the distance adjusting means is performed by adjusting the position of the light-collecting device with respect to the laser head to which the light-collecting device is attached, or by driving means for moving the laser head in the optical axis direction.
Further, while a certain degree of laser oscillation is occurring between the reflection means and the rear mirror of the laser oscillator, by driving a nozzle moving mechanism for moving the processing nozzle in a direction substantially perpendicular to the laser beam optical axis, the processing nozzle of the laser output measured by the laser output sensor at each pitch is moved at a predetermined amount pitches, on the basis of the measurement result, the optical axis of the axis and the laser beam of the pores of the processing nozzle is substantially coincident, the laser output Strength
The position of the processing nozzle with respect to the optical axis at which is maximized is determined.
Further, the measurement data of the laser output sensor is stored in the storage means, and the position of the processing nozzle with respect to the optical axis is automatically obtained by the calculation means based on the stored data.

The calculating means is constituted by a processor or the like of the control means of the laser processing apparatus. If the calculation is performed by this processor, it is not necessary to load special hardware on the laser processing apparatus and only add software. Can implement the present invention.

[0016]

FIG. 1 is a schematic diagram showing one embodiment of a laser processing apparatus for carrying out the present invention. The laser processing apparatus of this embodiment includes a carbon dioxide laser 1 and a laser output sensor 6 inside the laser 1 as a measuring device for measuring a laser output output from the laser 1. Resonator 2 in laser oscillator 1
A rear mirror 4 and an output mirror 5 are provided at both ends of the rear mirror 4.
A laser output sensor 6 is mounted behind the device. In this embodiment, the transmittance of the rear mirror 4 is 0.5%, and the transmittance of the output mirror 5 is 50%.

The laser output sensor 6 absorbs a small amount of laser light transmitted through the rear mirror 4 and converts it into heat, and measures the heat flow when escaping it to the outside with a thermocouple to measure the intensity of the laser output. Things.

The control device 10 of the laser processing apparatus includes a power supply 1
9, a voltage is applied to the electrodes 3 of the discharge tube of the resonator 2 to excite the laser medium in the discharge tube, thereby causing laser oscillation between the rear mirror 4 and the output mirror 5 to generate the laser beam 7. The output is output from the output mirror 5 side.

The control device 10 is constituted by a processor, storage means and the like, stores a machining program created in advance,
And a machining program storage / analyzing means 11 for sequentially reading and analyzing the machining program from the top is provided.
A motor control circuit 12 is provided for inputting a movement command or the like obtained by analysis by the processing program storage / analysis means 11 and for controlling a motor for moving the table 20 on which the work 21 is mounted, the processing head 9 and the like. . The motor control circuit 12 includes an X-axis motor 25 and a Y-axis motor 2 that drive the table 20 in the X-axis direction and the Y-axis direction on a horizontal plane.
6. The Z-axis motor 24 for moving the processing head 9 in the Z-axis direction perpendicular to the X-axis and the Y-axis, and further, the processing nozzle 23 attached to the tip of the processing head is moved on a plane parallel to the plane of the table 20. X-axis and Y-axis motors 27 and 28 for processing nozzles that move relatively to the processing head 9 in the X-axis direction and the Y-axis direction, and a condensing lens provided in the processing head 9 as a condensing device The lens drive motor 29 drives the lens 22 in the Z-axis direction. In addition, a reflection type optical component such as a parabolic mirror may be used as the light collecting device in addition to the light collecting lens.

Further, the control device 10 receives a laser output command obtained by the machining program storage / analysis means 11 and a feedback signal from a feedback circuit 14 which feeds back an output signal from the laser output sensor 6 and outputs a signal from the laser oscillator 1. There is provided a laser output control circuit 13 for feedback-controlling the voltage applied from the power supply 19 to the electrodes of the discharge tube so that the laser output matches the command value.

The above-mentioned machining program storage analysis means 1
1. Although the control device 10 is provided with a motor control circuit 12, a laser output control circuit 13, and a feedback circuit 14 in the same manner as the conventional control device, the embodiment of the present invention further includes a laser output monitor storage. Means 1
5. A laser output detection signal from the focal point / optical axis position calculating means 16 and the laser output sensor 6 is fed back to the feedback circuit 1.
4 is different from the conventional control device in that a changeover switch 30 is provided for switching between input to the control unit 4 and input to the laser output monitor storage unit 15. In addition, the laser output monitor storage means 15 can use the storage means provided in the conventional control device. Further, the focal point / optical axis position calculation means 16 can be used by the processor provided as the processing program storage analysis means 11. The control software may be set and stored so as to be executed. The control software may be set so that the processor executes both the switching of the switch 29 and the storage processing of the laser output detection signal in the laser output monitor storage circuit.

Further, a display device 17 such as a CRT or an LCD, and an operation panel 18 for inputting various commands and set values to the control device 10 are connected to the control device 10.

The laser beam 7 output from the laser oscillator 1 is guided to a processing head 9 via a reflecting mirror 8, and a condensing lens 22 provided in the processing head 9 as a condensing device.
And irradiates the work 21. In general, a plurality of reflecting mirrors are provided, but are omitted in the figure.

At the tip of the processing head 9, a processing nozzle 23
A hole having a diameter of about 2 mm is provided at the center of the processing nozzle 23, and a laser beam focused through the hole of the processing nozzle
Irradiated on top. The space between the processing nozzle 23 and the condenser lens 22 is a closed space except for the hole, and an assist gas is supplied to the closed space (this point is not shown in the drawing). Along with the irradiation, the assist gas is injected onto the work 21 from the hole.

The processing head 9 is driven and movable by a Z-axis motor 24 in a Z-axis direction perpendicular to the XY-axis plane of the table 20. Further, the condenser lens 22 mounted inside the processing head 9 is slidably mounted on the lens barrel 9 a of the processing head 9, and the condenser lens 22 is driven by a lens drive motor 29 that drives the condenser lens 22. It can be moved in the optical axis direction (Z-axis direction), and the position of the condensing point can be adjusted. Further, the processing nozzle 23 attached to the tip of the processing head 9 can be moved in the X-axis and Y-axis directions perpendicular to the optical axis by X and Y-axis motors 27 and 28 for driving the processing nozzle. Has become.

With the above configuration, when performing machining,
After mounting the work 21 on the table 20 and adjusting the focal point of the laser beam on the work 21 in the same manner as in the related art, the processing program stored and executed is executed by the processor of the processing program storage / analysis means 11, While outputting the laser beam 7 from the oscillator 1, the X-axis, Y-axis, and Z-axis motors are driven based on the processing program to drive the table 20 and the processing head 9 along the processing path specified by the processing program. And execute the processing.

In the ordinary processing described above, the output mirror 5
The laser beam 7 output from the laser beam is almost absorbed by the work and is subjected to laser processing. However, when the work surface reflects the laser light well, the laser beam is generated between the rear mirror 4 of the laser oscillator 1 and the surface of the work 21. Resonance may occur.

FIG. 4A is a view for explaining the principle of occurrence of laser resonance between the rear mirror 4 of the laser oscillator 1 and the surface of the work 21. The laser beam 7 entering the condenser lens 22 is condensed by the condenser lens 22 and is irradiated on the work 21. FIG. 4A shows a state in which a converging point is located at a position close to the surface of the work 21. In this case, the laser beam 7 is reflected on the surface of the work 21 and passes through the condensing lens 22 to become parallel light, and Returning to the oscillator 1. The returned laser beam is also reflected by the rear mirror 4 and irradiates the work surface again. This is repeated, and the
Then, laser resonance occurs between the workpiece and the work surface. FIG.
As shown in (a), even when the surface of the work 21 is not completely perpendicular to the optical axis of the laser beam, laser resonance occurs between the rear mirror 4 and the work surface.

On the other hand, as shown in FIGS.
As the focal point moves away from the work surface, the laser beam reflected by the work surface and returning through the condenser lens 22 is no longer parallel light. As a result, laser resonance between the rear mirror 4 and the work surface decreases.

As described above, when the focal point is near the work surface, laser resonance occurs between the rear mirror 4 and the work surface, and the measured value of the laser output temporarily increases. When the focal point moves away from the work surface, the amplification efficiency of the resonator deteriorates, the laser output decreases, and the measured value decreases. In the present invention, the position of the focal point is detected and the position of the focal point is adjusted using the output value of the laser output sensor 4 due to the laser resonance between the rear mirror 6 and the work 21. That is, the distance between the condenser lens 22 and the surface of the work 21 is adjusted. Further, the optical axis is adjusted.

As for the optical axis adjustment, a laser resonance is formed between the rear mirror 4 and the surface of the work as described above. The distance between the surfaces is fixed, and the processing nozzle driving motors 27 and 28 are driven to move the processing nozzle 23 in a direction substantially perpendicular to the optical axis. Then, as shown in FIG. 4D, the laser beam 7 radiated from the condenser lens 22 to the work 21 is processed by the processing nozzle 23.
When the laser beam deviates from the hole and hits the periphery of the nozzle hole, the state of laser resonance between the rear mirror 4 and the surface of the work breaks down, and the output value of the laser output sensor decreases. This makes it possible to obtain the positional relationship between the converged laser optical axis and the processing nozzle, and to adjust the position of the processing nozzle to the optimum position with respect to the laser optical axis.

Therefore, in the present invention, since it is an essential condition that the laser light is reflected on the work surface, the laser light is well reflected when the above-mentioned adjustment of the focal point and the adjustment of the optical axis are performed. A work to be performed or a test piece made of a material that reflects laser light well is prepared as a reflection unit.
The work material that reflects the laser light well depends on the wavelength of the laser oscillator to be used and needs to be selected. In the case of a carbon dioxide laser processing device (wavelength = 10.6 µm), a copper plate, a brass plate, a glossy stainless steel plate Alternatively, an aluminum alloy steel plate or the like may be used.

Therefore, the work 21 which reflects the laser light well as described above is mounted on the table 20, and the Z-axis motor 2
4 to set the tip of the processing nozzle 23 to a predetermined distance from the surface of the work 21 (the distance between the work surface and the tip of the processing nozzle is an optimum value in order to make the action of the assist gas effective during processing. When a focus point position adjustment command is input from the operation panel 18, the processor of the control device 10 starts the focus point position adjustment process shown in the flowchart of FIG.

First, the laser output control is switched from feedback control to open control, that is, the switch 30 in FIG. 1 is disconnected from the feedback circuit 14 and switched to the laser output monitor storage means 15 (step S).
1). Next, the position of the condenser lens 22 (lens drive motor 2)
9) is set to an initial value L0, and the lens drive motor 29 is driven via the motor control circuit 12 to position the lens at the position L = L0 (step S).
2). Next, a circular motion movement command of the set diameter is output to the X and Y axis motors that drive the table 20, and the table 20 is moved.
1. Make a circular motion relative to 1. In the present embodiment, a circular motion movement command that draws a circle with a diameter of 50 mm at about 3 m per minute is output. Further, the laser output command is output with a value much smaller than the output command of normal processing. For example, even with a laser processing apparatus having an output of 3 KW, 10
A laser output command of about W is set. In this embodiment, the set output command is set to 10 W (step S4).

Power supply 19 via laser output control circuit 13
Is applied to the electrodes 3 and 3 of the laser oscillator 1 so that a laser output of 10 W is produced. Since the feedback control is not performed and the open control is performed, the voltage applied to the electrodes 3 and 3 is constant, and the actual laser output changes. Although the laser output command is as small as 10 W and the measurement value detected by the laser output sensor 6 is also small, as described above, when laser resonance occurs between the surface of the work 21 and the rear mirror 4 of the laser oscillator 1, The output is about 700 W as described later. Therefore, in order to prevent the work from being deformed or oxidized at the time of laser resonance between the rear mirror 4 of the laser oscillator 1 and the surface of the work 21, the work is circularly moved and cooled by the processing in step S3 described above. It is like that.

As described above, the laser beam 7 output from the laser oscillator 1 is condensed by the condensing lens 22 and irradiates the surface of the work 21 through the hole of the processing nozzle 23.
The condenser lens 22 is set to an initial position L0 by the lens drive motor 29. Since this position L0 is selected as a position where the focal point is not on the surface of the work 21, the position L0 is selected. The laser oscillation between the laser and the rear mirror 4 of the laser oscillator 1 is small.

Then, the index i is set to 1 (step S5), the measured value D of the intensity of the laser output, which is the output of the laser output sensor 6, is read and stored as the laser output monitor storage means 15 provided in the storage means. The read measurement value D and the position L of the condenser lens 22 are stored in the address i corresponding to the index i in the table (step S6). Then, the index i is incremented by “1” and the focusing lens 22 is increased.
A predetermined movement amount δL is added to the position L, and a movement command to this position is output to move the condenser lens 29 to the position (step S7).

Next, it is determined whether or not the index i has exceeded the set value n (step S8). If not, the process returns to step S6, and the above-described processing in steps S6, S7 and S8 is performed on the index i.
Is repeatedly executed until exceeds the set value n. as a result,
The condenser lens 29 moves in steps of the set movement amount δL, and the measured value D measured by the laser output sensor 6 at each movement position L is stored in the table together with the position L of the condenser lens. Will be.

If the index i exceeds the set value n, step S
From 8, the process proceeds to step S 9, in which a laser output stop command is issued to stop the laser output and stop the circular motion of the table 20.

Then, the index is set to "1" (step S10), and the index i of the table provided in the storage means is set.
Is read (step S11), and it is determined whether the read laser output measurement value D is larger than the value of the register Dmax storing the maximum value (step S12). The register Dmax is initially set to "0" by default. If the read measurement value D is larger, this value is stored in this register Dma
x, and the position L of the condenser lens 29 read in step S11 is stored in a register Lmax for storing the position of the condenser lens at which the laser output measurement value becomes the maximum value (this register is also initially set to "0" Is set to ")
(Step S13). Next, the index i is set to “1”.
Increment is performed (step S14), and it is determined whether or not the value of the index i exceeds the set value n (step S15).
Until the set value n is exceeded, steps S11 to S
Step 15 is repeated. As a result, when the value of the index i exceeds the set value n, when the laser output sensor 6 detects the maximum value (Dmax) of the laser output by the laser output sensor 6, that is, The position L of the condenser lens when the laser oscillation between the rear mirrors 4 of the laser oscillator 1 is maximized and the focal point of the laser beam 7 is on the surface of the work 21 is stored. Become. Then, when the value of the index i exceeds the set value n, the condenser lens 29 is moved to the position stored in the register Lmax at that time and positioned (step S1).
6). As a result, the condenser lens 29 is positioned at a position where the focal point is located on the work surface, and the focal point position adjustment processing ends.

After the position of the focal point is adjusted in this way,
Adjustment of the optical axis position, that is, the processing nozzle 2 with respect to the optical axis
The position of No. 3 is adjusted. When this optical axis adjustment command is given, the processor of the control device starts the processing of FIG.

First, switching to open control (step T
1. The open control has already been switched in the focus point position adjustment, but this is performed for confirmation), and a half of the stroke moved by the optical axis adjustment from the current X-axis position x of the processing nozzle A position smaller than that is obtained, and a movement command to the position is output to the X-axis motor 27 for driving the processing nozzle. Assuming that it moves in the plus direction n times at intervals of δx for optical axis adjustment, a position (x−Δx) moved in the minus direction by Δx = n · δx from the current position x is output as an X-axis command position. (Step T2). Then, similarly to the position adjustment process of the focal point, a circular motion command is output to the table 20 (work 21), an output command of 10 W is output to the laser oscillator 1, and the laser oscillator 1
Output the laser beam 7 and irradiate the surface of the work 21 with laser light (steps T3 and T4).

Next, the index i is set to "1" (step T5), the output D of the laser output sensor 6 is read, and this data is stored in the address i of the table provided in the storage device corresponding to the index i. D and the position x of the X-axis of the processing nozzle
Is written (step T6), the index i is incremented by “1”, the movement command position to the X axis is increased by δx, and a command to this position is output to the motor control circuit 12 to output the X for driving the processing nozzle. The shaft motor 25 is driven (step T7). Then, it is determined whether or not the index i has exceeded the set value n (step T8).
Is repeatedly executed, and the measured value of the laser output at each position when the processing nozzle 23 is moved at intervals of δx in the X-axis direction is stored in the storage device.

When the index i exceeds the set value n, the laser output is stopped and the circular motion of the table 20 (work 21) is stopped (step T9), and the index i is set to "1" again (step T10). Then, the data D and X of the address i of the table in the storage device corresponding to the index i are read (step T11), and it is determined whether or not the measured value D of the laser output is larger than the value of the register Dmax for storing the maximum value ( Step T12) If it is larger, the measured value D is stored in the register Dmax, and the position x of the X-axis of the processing nozzle read out in Step T11 is set to the X-axis when the maximum value of the laser output measured value is measured. The position is stored in the register Xmax (step T13). The registers Dmax and Xmax are initially set, and initially "0" is set. If the measured value D is equal to or smaller than the value stored in the register Dmax in step T12, the process in step T13 is not executed. Then, the index i is incremented by "1" (step T14), and it is determined whether or not the index i exceeds the set value n (step T15).
Steps T11 to T15 are repeatedly executed.

As a result, the register Dmax stores the maximum measured value among the n measured values of the laser output, and the register Xmax stores the X-axis position of the processing nozzle at that time (for processing nozzle driving). (Movement position by the X-axis motor 27) is stored. The fact that the measured value of the laser output is the maximum means that the processing nozzle 23 is not irradiated with the laser beam 7 as shown in FIG. When the X-axis position x at that time is in the X-axis direction, it means an optimum position of the processing nozzle with respect to the optical axis.

Therefore, when the index i exceeds the set value n,
The process shifts from step T15 to step T16 to drive the X-axis motor of the processing nozzle drive motor via the motor control circuit 12 to move the X-axis direction position x of the processing nozzle 23 to the position stored in the register Xmax (step S15). T
16).

Next, a process for obtaining and adjusting the optimum position of the processing nozzle 23 with respect to the optical axis in the Y-axis direction is executed. In this case, the processing is performed from step T2 to step T1.
In the processes up to 6, only the X-axis and the x-position need to be changed to the Y-axis and the y-position, so detailed processes are omitted.

As described above, by utilizing the laser resonance generated between the rear mirror 6 of the laser oscillator 1 and the surface of the work, the position of the focal point is adjusted, and the optical axis of the laser beam with respect to the processing nozzle 23 is adjusted. become.

In the above-described embodiment, an example of the laser processing apparatus in which the laser output sensor 6 for measuring the laser output is provided inside the laser oscillator 1 has been described. However, the laser output sensor is provided outside the laser oscillator. The present invention can be applied to a laser processing apparatus. FIG. 2 shows an example in this case. 2, 40 is a laser oscillator, 41 and 42 are a rear mirror and an output mirror of the laser oscillator 40, and 43 is a reflecting mirror. In this embodiment, a mirror having a transmittance of about 1% is used as the reflecting mirror 43, and a laser output sensor 44 is disposed behind the reflecting mirror 43, and the laser output measured by the laser output sensor 44 is used. Is sent to the controller 45. The configuration, processing, and the like of the control device 45 are the same as those shown in FIG.
Since they are the same as the embodiment shown in FIG. That is, the only difference from the embodiment shown in FIG. 1 is that the laser output sensor is provided outside the laser oscillator.

In the embodiment shown in FIG. 1, the work for reflecting the laser light, which is mounted on the table 20, is used as the means for reflecting the laser light. However, in the example shown in FIG. The above-mentioned well-reflecting member is attached to the peripheral surface of the drum 45 by using the above-mentioned drum 45. At the time of adjusting the focal point and the position of the optical axis, the laser beam is arranged so that the optical axis of the laser beam is irradiated perpendicularly to the peripheral surface of the drum 45, and the drum 45 is rotated at a predetermined speed by a motor or the like. do it. Further, as shown in FIG. 3, a measuring disk 46 made of a material that reflects the laser light rotated by the motor 47 well.
May be used as a reflection means, and the position of the focal point and the position of the optical axis may be adjusted by arranging the laser beam on the surface of the disk 46 so that the optical axis is vertical. When such a reflecting means is used, the reflecting means itself moves, so that the processing of steps S3 and T3 in FIGS. 5 and 6 is not required.

As an example of adjusting the position of the condensing point by changing the position of the condensing lens, an experiment was conducted under the following conditions, and the results shown in Table 1 were obtained.

Experimental conditions Laser oscillator: Rated output 3 KW Condensing lens: Focal length 190 mm Workpiece: Brass plate of thickness 3 mm Working nozzle hole diameter: 2 mm Distance between working nozzle and work: 4 mm (fixed) Laser output command: 10 W 1 Height of Condensing Lens Laser Actual Output (Distance between Work Surface and Lens Bottom) mm (Measured Value) W 183.0 187 183.5 221 184.0 241 184.5 268 185.0 314 185.5 421 186 0.0 609 186.5 555 187.0 602 187.5 756 188.0 756 188.5 528 189.0 508 189.5 395 190.0 281 No work is placed. When the laser output was measured by adjusting the axial position, the following Tables 2 and 3 were obtained. Table 2 Movement amount of processing nozzle in the X-axis direction mm Laser output (measured value) W-1.5 10 -1.0 127 -0.5 482 0.0 743 +0.5 402 +1.0 395 +1.5 10 Table 3 The amount of movement of the processing nozzle in the Y-axis direction mm Laser output (measured value) W -1.5 10 -1.0 401 -0.5 709 0.0702 +0.5 676 +1.0 355 +1.5 10 In the above experimental example. In adjusting the focal point position, the distance between the work surface and the lens bottom surface is 187.5 mm or 18 mm.
At the position of 8.0mm, the laser output measured value is the maximum 756W
In the processing shown in FIG. 5, the position of 187.5 mm or 188.0 mm is stored in the register Lmax as the position of the condenser lens, and the condenser lens is set as the position where the focal point becomes the work surface. (The position of the processing head 9 with respect to the lens barrel 9a) is set. In the optical axis position adjustment, the X-axis position of the processing head is at the position of “0.0” where the measured value of the laser output is 743 W, and the Y-axis position is “−0.5” where the measured value of the laser output is 709 W. "Position.

As is clear from the above-mentioned experimental example, there is a range during which the measured value of the laser output sharply increases and then sharply decreases. This means that the maximum value varies, so rather than determining the position based on the maximum value of the laser output measurement value, take the intermediate point between the sharp rise and fall of this measurement value. Is also good. Further, an intermediate point of the position between the time when the measured value becomes equal to or more than the predetermined value and the time when it becomes equal to or less than the predetermined value may be set.

In the above experimental example, in adjusting the focal point position, the position of the condenser lens is changed from "185.5" to "186.
0 ”indicates the maximum rise change amount,
When “188.0” changes to “188.5”, the maximum amount of change in falling is shown.
"187.0" at the midpoint between "6.0" and "188.0"
May be set as the position where the converging point is on the work surface. Also, the measured value of the laser output is a set value, for example, 400
Assuming that an intermediate point when W or more is taken, in the example of Table 1,
"18" at the midpoint between "185.5" and "189.0"
7.25 "is set as the position of the condenser lens having the focal point on the work surface.

Similarly, in the optical axis adjustment, the midpoint between the rise and fall of the measured value of the laser output or the intermediate position between the measured values equal to or larger than the set value is set as the position of the processing nozzle with respect to the optical axis. You may make it.

Further, in each of the above embodiments, an example has been shown in which the control device of the laser processing apparatus automatically adjusts the position of the focal point and the optical axis position with respect to the processing nozzle. By manual operation, the position of the condenser lens where the focal point becomes the work surface or the position of the processing nozzle where the optical axis of the laser beam almost coincides with the center of the hole of the processing nozzle is detected. The position adjustment and the position adjustment of the processing nozzle may be performed. In this case, the output of the laser output sensor 6 is displayed, and the lens drive motor 29 for driving the condenser lens 22 by a manual switch of the operation panel 18 is sequentially driven at a predetermined pitch amount to display the displayed laser. The position where the measured value of the output sensor 6 is the largest, or the intermediate position between the sudden rise and fall of the measured value,
Furthermore, an intermediate position where a measured value equal to or more than a predetermined value is obtained may be a position of the condenser lens whose focal point is on the work.
Similarly, in the optical axis adjustment, similarly, the X-axis motor and the Y-axis motor for driving the processing nozzle by manual feed are sequentially driven at a predetermined pitch, and the maximum value of the measurement value of the laser output sensor 6 at each pitch (or X-axis where the sudden rise, fall, or measurement value of a predetermined value or more is detected, and the maximum value (or the measurement value of a sudden rise, fall, or a measurement value of a predetermined value or more) is detected. , The position of the Y axis (or the intermediate position between the rapid rise and fall of the measured value, or the intermediate position at which the measured value equal to or more than the predetermined value is obtained) may be set as the position of the processing nozzle with respect to the optimal optical axis. .

Further, in the above-described embodiment, the distance between the workpiece surface and the tip of the processing nozzle is fixed to a predetermined value. This distance is fixed because the assist gas ejected from the hole of the processing nozzle 23 works effectively at the time of laser processing. When the distance does not need to be fixed, the mirror of the processing head 9 is used. It is not necessary to change the position of the condenser lens 22 with respect to the cylinder 9a to adjust the distance between the work 21 and the condenser lens 22. In this case, by changing the Z-axis position of the processing head 9 by a Z-axis motor that drives the processing head 9 itself in the Z-axis direction (the optical axis direction of the condenser lens), The focusing lens can be positioned at a position where the focusing point is on the surface of the work 21 by moving the focusing lens. Therefore, in this case, the lens drive motor 29 for driving the condenser lens 22 becomes unnecessary.

The condenser lens 2 is driven by the Z-axis motor 24.
When adjusting the distance between the workpiece 2 and the workpiece, if the distance between the processing nozzle 23 and the workpiece 21 is to be maintained at a predetermined value and the influence of the assist gas is to be maintained in an optimal state,
The processing nozzle 23 may be movable in the Z-axis direction with respect to the lens barrel 9a of the processing head 9, and the processing nozzle 23 may be moved to obtain an optimum distance between the processing nozzle and the workpiece surface.

[0059]

According to the present invention, the laser resonance generated when the focal point of the laser beam is located near the surface of the reflecting means between the reflecting means such as a work which reflects the laser light well and the rear mirror of the laser oscillator. Since the distance between the condensing device and the reflection means (work) is adjusted and the position of the processing nozzle with respect to the optical axis of the laser beam is adjusted, a laser processing device having a measuring device for measuring a laser output is required. It is possible to adjust the position of the condensing point and adjust the positions of the optical axis and the processing nozzle without adding any special means. In addition, only by adding control software to the control device of the laser processing device, the adjustment of the focal point position and the adjustment of the optical axis and the position of the processing nozzle are automatically performed without adding any special hardware. An executable laser processing apparatus can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of a laser processing apparatus for implementing the present invention.

FIG. 2 is a schematic view of another embodiment of another laser processing apparatus for implementing the present invention.

FIG. 3 is an explanatory diagram of one embodiment of a reflecting means used in the present invention.

FIG. 4 is an explanatory diagram illustrating conditions under which laser resonance occurs between a reflecting means (work) and a rear mirror of a laser oscillator according to the present invention.

FIG. 5 is a flowchart of the focal point position adjustment executed by the control device of the laser processing apparatus in each embodiment of the present invention.

FIG. 6 is a flowchart of the adjustment of the optical axis of the laser beam and the position of the processing nozzle performed by the control device of the laser processing apparatus in each embodiment of the present invention.

[Explanation of symbols]

 1, 40 Laser oscillator 4, 41 Rear mirror 6, 44 Laser output sensor 7 Laser beam 8, 43 Reflecting mirror 9 Processing head 10 Control device of laser processing device 20 Table 21 Work 22 Condensing lens 23 Processing nozzle 24 Z-axis motor 25 X-axis motor 26 Y-axis motor 27 X-axis motor for processing nozzle drive 28 Y-axis motor for processing nozzle drive 29 Lens drive motor 45 Measurement drum 46 Measurement disk

Claims (8)

(57) [Claims] 1. A laser beam condensing device comprising: a laser oscillator; a measuring device for measuring a laser output intensity of the laser oscillator; and a condensing device for condensing a laser beam on a workpiece. An adjusting method for adjusting a position of a point, comprising: arranging a reflection means for reflecting a laser beam near a laser beam converging point; and collecting the laser beam so as to maximize a laser output intensity measured by the measuring device. In front of the light spot
An adjustment method for adjusting the position with respect to the reflection means . 2. The adjustment method according to claim 1, wherein the adjustment of the position of the laser converging point with respect to the reflecting means is performed by moving the condensing device or the reflecting means in the optical axis direction of the laser beam. 3. A laser oscillator, a measuring device for measuring the intensity of the laser output of the laser oscillator, a storage device for storing the measured laser output intensity, and a laser beam arranged near the focal point of the laser beam. Reflection means for reflecting light,
In a laser processing apparatus comprising: a condensing device for condensing a laser beam on the reflecting unit; and a distance adjusting unit for adjusting a distance between the condensing device and the reflecting unit. The intensity of the laser output of the laser oscillator measured by the measuring means while changing the distance between the optical device and the reflecting means is stored in the storage device, and the position of the focal point is determined based on the stored laser output data. A laser processing apparatus, wherein a focal point position is obtained by a calculating means for calculating, and a distance between the light collecting device and the reflecting means is adjusted by the distance adjusting means based on the focal point position. 4. The distance adjusting means adjusts a distance between the light-collecting device and the reflecting means by adjusting a position of the light-collecting device with respect to a laser head on which the light-collecting device is mounted. 3. The laser processing apparatus according to 3. 5. A laser oscillator, a measuring device for measuring the intensity of the record over The output, a processing nozzle which emits a focusing device for focusing the laser beam onto the workpiece, the laser light condensed, An adjusting method for adjusting a position of a laser beam optical axis in a laser processing apparatus having a nozzle moving mechanism for moving a processing nozzle in a direction substantially perpendicular to a laser beam optical axis, comprising: A reflecting means for reflecting light, a rear mirror of the laser oscillator and the reflecting means;
While oscillating between the stage and the stage, the nozzle moving mechanism is driven to adjust the processing nozzle position so that the laser output intensity measured by the measuring device is maximized, and the laser beam optical axis position with respect to the processing nozzle Adjustment method to adjust. 6. A laser oscillator, a measuring device for measuring the intensity of the laser output of the laser oscillator, a storage device for storing the measured laser output, and a condensing device for condensing the laser beam on a work. A processing nozzle that emits a focused laser beam, a nozzle moving mechanism that moves the processing nozzle in a direction substantially perpendicular to the laser beam optical axis, and a laser beam that is disposed near a laser beam focusing point. A laser processing apparatus comprising: a reflecting means that performs oscillation between a rear mirror of the laser oscillator and the reflecting means.
In this state, the processing nozzle is moved by the nozzle moving mechanism, the intensity of the laser output of the laser oscillator measured by the measuring means is stored in the storage device, and the laser beam is output based on the stored laser output data. A laser processing apparatus, wherein an optical axis position is obtained by calculation means for calculating an optical axis position, and the processing nozzle is moved with respect to a laser beam optical axis by the nozzle moving mechanism based on the optical axis position. 7. The method according to claim 1, wherein the measurement of the intensity of the laser output from the laser oscillator is performed while moving the reflection means in a direction substantially perpendicular to the laser beam optical axis. The adjustment method described. 8. The laser processing apparatus according to claim 3, wherein said reflecting means includes means for moving a laser beam reflecting surface.