JP3167977B2 - Bend mirror device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates Bendomira ｰ_So location to be irradiated on the workpiece through the reflected condenser lens of the laser beam with variable curvature mirror from the laser oscillator, the variable curvature mirror especially according to the laser processing conditions the amount of change in the curvature of the reflecting surface about Bendomira ｰ_So location to properly controlled.

[0002]

2. Description of the Related Art Conventionally, since a laser beam has a divergence angle, a spot diameter of the laser beam changes depending on a distance from a laser oscillator. In the laser processing machine of the optical movement type, the processing area length is long, so that the laser beam passes through a combination of a plurality of fixed concave and convex mirrors or a transmission lens so that the beam diameter of the laser beam becomes uniform. The light is guided to a certain condensing lens (transmission lens) and condensed.

The spot diameter of the focused laser beam depends on the beam diameter of the laser beam incident on the condenser lens, and the focal length of the laser beam on the condenser lens is incident. The influence of the divergence angle of the laser beam is added. That is, when the beam diameter of the incident laser beam and the distance from the laser oscillator to the condenser lens are different, the spot diameter (condensed diameter) and the focal length change.

[0004] It has been known that there are light beam diameters and Rayleigh lengths that are suitable for the work material, plate thickness, and processing method. We change lens and use properly.

[0005]

By the way, conventionally, in order to obtain a light-collecting diameter suitable for the material, plate thickness and processing method of the work, the focus length is changed by replacing the light-condensing lens each time. Therefore, there is a problem that workability is poor and automation is difficult to achieve.

[0006] With the necessity of replacing the condenser lens, replacing the condenser lens complicates the structure of the laser processing head and increases the cost associated therewith, and the tact time for replacing the condenser lens is long. There was a problem. In addition, there is a problem that there is a structural upper limit in increasing the focal length of the condenser lens.

In addition, there has been a problem in the related art that it is impossible to cope with individual differences in laser oscillators and deterioration of optical systems such as mirrors.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make it possible to freely change the curvature of the reflecting surface of a bend mirror without using a plurality of condenser lenses. One of the material of the workpiece by the condenser lens, the plate thickness, proper control the proper spot diameter to suit the difference in the processing method is to provide a Bendomira ｰ_So location that can realize stable laser machining was.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a pressure chamber between a back surface of a mirror having a reflecting surface for reflecting a laser beam and a mirror block on which the mirror is mounted. Along with the provision, a storage chamber is provided in the mirror block, and a large number of gas injection ports for injecting pressurized gas at an equal pressure from the storage chamber to the entire back surface of the mirror are provided. And a mirror reference surface is provided on the outer peripheral side of the slit.

Therefore, after the gas pressure in the pressurized chamber is maintained in a stable state, the gas is ejected from a number of gas outlets to the back of the reflecting surface of the mirror with uniform pressure, so that the curvature of the reflecting surface in a stable state is maintained. Is obtained. Further, the mirror heated by the laser beam is efficiently cooled by the pressurized gas uniformly jetted from the many gas jetting surfaces to the back of the reflecting surface.

The mirror reference surface on the outer periphery of the mirror is positioned at the mirror mounting reference position. Since the deformation distortion of the mirror that occurs when the curvature of the mirror changes is absorbed by the slit on the inner peripheral side of the mirror reference plane, the mirror reference plane can be prevented from being affected by the deformation distortion of the mirror. As a result, the mirror is always mounted at the mirror mounting reference position in a stable state.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the Bendomira ｰ_So location of the present invention will be described with reference to the drawings.

Referring to FIG. 4, a laser processing apparatus 1 according to the present embodiment includes a laser beam LB oscillated from a laser oscillator built in a processing apparatus main body (not shown).
Is guided to a condenser lens 7 provided inside a laser processing head 5 through, for example, a variable curvature mirror 3 as a bend mirror. The laser beam LB condensed by the condensing lens 7 passes through the injection nozzle 9 provided at the tip of the laser processing head 5 and is irradiated on the work W. For example, the laser beam LB is focused on the laser processing point of the work W transferred and positioned by the numerically controlled work transfer positioning device, and laser processing such as cutting into a desired shape is performed.

The laser processing head 5 is a ball screw 1 which is driven to rotate by a processing head drive motor 11 as a processing head moving device provided in the processing apparatus main body.
In other words, the injection nozzle 9 is provided movably so as to be able to move up and down via the 3A so as to approach and separate from the work W.

Further, the condenser lens 7 is provided inside the laser processing head 5 via a ball screw 13B which is driven to rotate by, for example, a condenser lens driving motor 15 as a condenser lens moving device provided in the laser processing head 5. And can be moved up and down. The moving distance of the condenser lens 7 will be described later as a variable B-axis value (B value) in FIG. The processing head drive motor 11 and the condenser lens drive motor 15 are each a control device 1 shown in FIG.
7 is electrically connected.

Generally, since the laser beam LB has a divergence angle, the laser beam LB does not travel with a uniform beam diameter but gradually spreads as shown in FIG. Therefore, the spot diameter of the laser beam LB at the laser processing point changes due to the difference in the distance from the laser oscillator to the condenser lens 7.

The spot diameter of the laser beam LB condensed by the condenser lens 7 depends on the beam diameter of the laser beam LB incident on the condenser lens 7. The focal length of the beam LB is added with the influence of the divergence angle of the incident laser beam LB on the focal length of the condenser lens 7 itself. That is, when the beam diameter of the incident laser beam LB and the distance from the laser oscillator to the condenser lens 7 are different, the spot diameter and the focal length change.

For example, when the beam diameter D _L of the laser beam LB incident on the condenser lens 7 is large, a small spot diameter d _L is obtained with a short focal length Lf _L as shown by a solid line in FIG. However, when the beam diameter D _S incident on the same condenser lens 7 is small, a large spot diameter d _S is obtained with a long focal length Lf _S as shown by a dotted line in FIG.

In the laser processing of the present invention, the beam diameter D of the laser beam LB incident on the condenser lens 7 by the light control device.
The spot diameter of the laser beam LB can be changed according to the material and thickness of the work W and the processing method without changing one condensing lens 7 so that the spot diameter is suitable for laser processing. Is to be adjusted.

The light control device means a spot diameter d ₀ (such as d _L or d _S ) at a laser processing point suitable for a material, a plate thickness, and a processing method of the work W. This is a device that changes the beam diameter D (such as D _L and D _S ) of the laser beam LB incident on the condenser lens 7.

The variable curvature mirror 3 used as a light control device which is a main part of the embodiment of the present invention is mounted on a bend block 19 as shown in FIG. Is reflected in the direction of the condenser lens 7, and is provided so that the curvature of the reflection surface M can be freely changed and adjusted.

[0022] Referring to FIG. 2, in the present embodiment, the mirror 21 bottom corresponding to the reflecting surface M is has no thin and ing cylindrical, cylindrical with the reflecting surface M to the outer mirror A pressure chamber 25 is provided between the back surface of the reflection surface M and the end surface of the mirror block 23 and is fixed to the block 23 and integrally fixed with bolts BT.

The mirror block 23 is provided with a storage chamber 27 inside the mirror block 23 near an end face constituting the pressurizing chamber 25, and as shown in FIG.
7 and the pressurizing chamber 25 communicate with each other through a number of small-diameter holes.
9 is provided. As is clear from FIGS. 2 and 3, the large number of gas outlets 29 transmit the pressure fluid to the reflecting surface M.
It is provided so as to squirt toward the entire back surface of the.

The mirror block 23 has a storage chamber 27.
A gas supply passage 31 communicating with the pressure chamber 25 and a gas exhaust passage 33 communicating with the pressurizing chamber 25 are provided. The gas supply path 31 of the mirror block 23 is connected to a gas supply port C via a supply side gasket 35, and a pressure gas such as air pressure or another gas is supplied to the gas supply port C. The gas exhaust path 33 communicates with a gas exhaust port D via an exhaust gasket 37.

The mirror 21 is provided with a slit 39 on the outer circumference of the reflection surface M, which is a relief groove when the reflection surface M is deformed. Further, a mirror reference surface 41 is provided on the outer peripheral side of the slit 39.

The thin reflecting surface M of the mirror 21 is always in a concave state when no pressure is applied. For example, when the reflecting surface M is processed into a flat surface in a state where the mirror 21 is pressed outward from the back surface of the thin reflecting surface M with a uniform pressure, if the pressing force is eliminated, the mirror 21 is always in a concave state. .

The above-mentioned mirror 21 and mirror block 23
Is fitted inside a cylindrical mirror mount base 45 provided with an opening 43 on the bottom surface, such that the reflection surface M of the mirror 21 faces the opening 43. Mirror 21
The mirror reference surface 41 on the outer periphery of the mirror mount base 4
5 is abutted against a reference surface at the bottom and positioned at a reference position. Since the slit 39 is provided on the inner peripheral side of the mirror reference surface 41, the deformation distortion of the mirror 21 generated when the curvature of the mirror 21 changes is absorbed by the slit 39. The influence from deformation distortion can be avoided. Therefore, the mirror 21 is always mounted on the mirror mount base 45 and the bend block 19 in a stable state.

On the back surface of the mirror mount base 45, a cooling block 49 having a cooling jacket 47 into which cooling water flows is integrally fixed by bolts BT. The cooling jacket 47 is formed by providing a groove portion 51 on the back surface of the cooling block 49 and covering the opening of the groove portion 51 with a packing 53. The back surface of the cooling block 49 is covered by a cooling block cover 55 and is bolted by BT. Fixed.

Referring to FIG. 1, a pressure gas such as air pressure or another gas supplied to the gas supply port C is configured such that the gas pressure is adjusted by a pressure adjusting device 57. Is a mechanism controlled by the controller 17 to change and adjust the curvature of the reflection surface M of the curvature variable mirror 3 according to the laser processing conditions.

More specifically, the gas supply port C is connected to the A port of a servo valve 61 such as an electropneumatic regulator through a mirror side gas supply pipe 59, and the P port of the servo valve 61 is connected to the servo port. Valve side gas supply pipe 6
3 is connected to a working gas supply source 65 for supplying a pressure gas such as air pressure or another gas. The T port of the servo valve 61 is configured to be discharged to the outside air via an exhaust filter 69 via a servo valve side gas exhaust pipe 67.

A servo valve 61 is connected to the gas supply pipe 59 on the mirror side.
And a gas supply port C, an accumulator tank 71 branched and connected, and a pressure sensor 73 as a pressure detector for detecting gas pressure, for example, are provided. The pressure sensor 73 serves as a curvature variable mirror control device. For example, via the servo control amplifier 75, the servo valve 61
Is electrically connected to The servo control amplifier 75 is electrically connected to the control device 17 that controls the overall operation of the laser processing device 1.

The gas exhaust port D is connected to the gas exhaust pipe 77.
And, it is configured to be discharged to the outside air via an exhaust filter 69 via an orifice 79.

As shown in FIG. 1, the control unit 17 includes, for example, a CPU 81 as a central processing unit.
An input device 83 and a display device 85 for inputting information such as a material, a plate thickness, and a processing method of the work W, processing point coordinates, data of a change amount of a curvature of the curvature variable mirror 3 and data of a focal length;
Based on a memory 87 for storing input data and a spot diameter d ₀ and a spot position (focal point) of the laser beam LB, based on a relational expression between the focal length and the amount of change in curvature of the curvature variable mirror 3 according to the coordinates of the processing point. An arithmetic unit 89 for calculating the length Lf ₀ ) and the amount of change in the curvature of the curvature variable mirror 3 is connected.

Further, the CPU 81 controls the curvature of the variable curvature mirror 3 obtained on the basis of the information such as the material, the thickness, and the processing method of the work W so as to match the amount of change of the curvature with the focal length of the condenser lens 7. A comparison / determination device 91 that issues a command to the servo control amplifier 75 so as to change the curvature of the variable mirror 3 is connected.

With the above configuration, the control device 17 uses the laser processing conditions of the work W and the X and Y coordinate values of the work W (coordinate values in the front, rear, left and right directions on the plane of the work W) for determining the laser processing area. The gas pressure for obtaining the desired amount of deformation of the curvature of the reflection surface M of the mirror 21 is calculated in advance by a calculation device 89 from a database stored in a memory 87 and compared and determined by a comparison determination device 91. It is determined. The controller 17 maintains the determined gas pressure.
Is sent to the servo control amplifier 75, and the servo valve 61 operates.

The pressurized gas supplied from the working gas supply source 65 via the servo valve side gas supply pipe 63 is supplied to the servo valve 61.
The gas supply pipe 59 from the P port to the mirror side through the A port
To the gas supply port C of the variable curvature mirror 3. At this time, the pressure of the pressurized gas supplied via the servo valve 61 is stabilized by the accumulator tank 71, and the data of the gas pressure detected by the pressure sensor 73 is fed back to the servo control amplifier 75 as needed, so that the servo valve 61 As it operates, a stable gas pressure is maintained.

Further, the pressurized gas flows into the storage chamber 27 from the gas supply port C via the gas supply path 31, and the pressurized gas in the storage chamber 27 is supplied from the gas outlets 29 to the pressurized chamber 25.
Is jetted onto the back surface of the reflecting surface M of the mirror 21 with a uniform pressure. When the mirror 21 is pressed from the back surface, the curvature of the reflection surface M is deformed. The injected pressure gas is supplied to the pressurizing chamber 2
5 to a gas exhaust port D via a gas exhaust path 33. Since the gas pressure in the pressurizing chamber 25 is maintained in a stable state by the operation of the pressure adjusting device 57, the curvature of the reflection surface M of the mirror 21 is maintained.

Further, the mirror 21 heated by the laser beam LB is efficiently cooled by the pressurized gas which is uniformly jetted from the many gas jetting surfaces to the back surface of the reflecting surface M, as shown in FIG. Since the cooling block 49 is constantly cooled by the cooling water, the heat of the mirror 21 is absorbed by the cooling block 49 from the outer peripheral surface of the mirror 21 via the mirror mount base 45. Therefore, mirror 2
1 is minimized.

As described above, when the pressure of the pressurized gas is adjusted, for example, when the gas pressure is adjusted from small to large, the reflection surface M of the mirror 21 is sequentially changed to a concave surface as shown by a dotted line in FIG. The curvature can be freely changed from a flat surface as shown by a solid line in FIG. 1 to a convex surface as shown by a dashed line in FIG.

Accordingly, the curvature of the curvature variable mirror 3 is controlled by the servo control amplifier 75, and the reflected laser beam LB, for example, as shown in FIG.
Is reduced and expanded, the size of the beam diameter D of the laser beam LB incident on the condenser lens 7 can be freely changed and adjusted. It is possible to minimize the difference in the processing area in the condensing diameter, and the material of the work W,
Since a laser beam LB having a condensing diameter and a Rayleigh length suitable for the plate thickness and the processing method can be obtained, the laser processing is stabilized and the laser processing capability is improved.

Referring to FIG. 7, the relationship between the gas pressure and the radius of curvature of the reflecting surface M of the mirror 21 is, for example, such that the reflecting surface M of the mirror 21 is substantially flat when the gas pressure is about 3.2 kgf / cm ^2. And the radius of curvature (-side) of the concave surface changes to become smaller as the gas pressure becomes smaller, and the radius of curvature (+ side) of the convex surface becomes smaller as the gas pressure increases. I understand.

Referring to FIG. 8, there is shown a relationship between the condensing diameter d ₀ at a laser processing point (a position at a distance of 5.2 m from the mirror 21) when the gas pressure is changed. The condensing diameter d ₀ is substantially a linear function d ₀ = −3 with respect to the gas pressure P.
It can be approximated by 9.925P + 578.26.

Referring to FIG. 9, the focal position obtained at the laser processing point is such that the wavefront curvature changes when the laser beam LB propagates, so that the variable B-axis value of the condenser lens 7 changes with respect to the gas pressure. And B = 0.86P + 10.
It turns out that it changes at 08. Therefore, in the actual laser processing, an arbitrary focused diameter at a certain gas pressure can be obtained, but at the same time, the focal position B value also needs to be considered according to the above equation.

The present invention is not limited to the above-described embodiment, but can be implemented in other modes by making appropriate changes.

As the pressure adjusting device 57, the aforementioned FIG.
Instead of the servo valve 61 in the embodiment, a proportional electromagnetic pressure control valve 93 can be used as shown in FIG. In this case, the data of the gas pressure detected by the pressure sensor 73 is fed back to the servo control amplifier 75 similar to that shown in FIG. 1 as needed, and the proportional electromagnetic pressure control valve 93 is operated, so that a stable gas pressure is obtained. Will be maintained. Other configurations are almost the same as those of the embodiment of FIG.

Alternatively, instead of the servo valve 61 in the embodiment of FIG. 1 described above, as shown in FIG. 6, for example, a predetermined desired gas is set using a fixed pressure reducing valve 95A and a solenoid valve 97A. Setting 1 for obtaining pressure
And the other fixed pressure reducing valves 9 in the same manner as in the setting 1 stage.
5B and a plurality of stages including a stage for obtaining another desired gas pressure set in advance by using the solenoid valve 97B and a stage for obtaining another desired gas pressure in the same manner. It can also be configured to control.

[0047]

As can be understood from the above description of the embodiments of the present invention, according to the present invention, after the gas pressure in the pressurizing chamber is maintained in a stable state, the number of gas outlets is increased. Since the jet can be jetted with even pressure to the back surface of the reflecting surface of the mirror, a stable curvature of the reflecting surface can be obtained. Further, the mirror heated by the laser beam can be efficiently cooled by the pressurized gas which is uniformly jetted from the many gas jetting surfaces to the back of the reflecting surface.

Further, the mirror reference surface on the outer peripheral portion of the mirror is positioned at the mirror mounting reference position. Since the deformation distortion of the mirror generated when the curvature of the mirror changes in the slit on the inner peripheral side of the mirror reference plane can be absorbed, the mirror reference plane can be prevented from being affected by the deformation distortion of the mirror. As a result, the mirror can be mounted at the mirror mounting reference position in a constantly stable state.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram of a curvature variable mirror according to an embodiment of the present invention.

FIG. 2, showing an embodiment of the present invention, is a side view illustrating a cross section of a variable curvature mirror.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a partial schematic explanatory view of a laser processing apparatus provided with a variable curvature mirror according to the embodiment of the present invention.

FIG. 5 is a block diagram showing another embodiment and showing a pressure adjusting device including a proportional electromagnetic pressure control valve.

FIG. 6 is a partial gas pressure circuit diagram showing a pressure regulator using a fixed pressure reducing valve and a solenoid valve according to another embodiment.

FIG. 7 is a graph showing a relationship between a gas pressure and a radius of curvature of a mirror.

FIG. 8 is a graph showing the relationship between the condensing diameters at the laser processing point when the gas pressure is changed.

FIG. 9 is a graph showing a relationship between a gas pressure and a focal position B value obtained at a laser processing point.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser processing device 3 variable curvature mirror 5 laser processing head 7 condenser lens 17 control device 21 mirror 23 mirror block 25 pressurizing chamber 27 storage chamber 29 gas ejection port 39 slit 41 mirror reference surface 57 pressure adjusting device 61 servo valve 71 accumulator Tank 73 Pressure sensor 75 Servo control amplifier (variable curvature mirror control device) M Reflective surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-39281 (JP, A) JP-A-10-85979 (JP, A) JP-A-8-318383 (JP, A) JP-A-9-99 293915 (JP, A) JP-A-11-14945 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 26/00-26/073 G02B 5/10 G02B 7/198

Claims (1)

(57) [Claims] 1. A back surface of a mirror (21) having a reflection surface (M) for reflecting a laser beam (LB) and the mirror (2).
A pressure chamber (25) is provided between the mirror block (23) and the mirror block (23) to which the mirror block (23) is mounted.
A plurality of gas injection ports (29) for injecting a pressurized gas at a uniform pressure from the storage chamber (27) to the entire back surface of the mirror (21). Bendomira ｰ_So location, wherein the mirror reference plane be provided on the outer peripheral side of the slit provided with a slit over around the outer periphery of the reflecting surface.