JPH07232290A - Focus adjusting device for laser beam machine - Google Patents

Abstract

PURPOSE:To provide a focus adjusting device for laser beam machine to automatically execute focus distance adjusting of laser beam in laser machining. CONSTITUTION:The device is provided with a laser oscillator 1, a beam condensing lens 4 to condense a laser beam 2, a condensing lens control part 5 to move the condensing lens 4, a laser beam detector 7 to detect the laser beam passed the condensing lens 4 and a focus distance operation part 8 to operate a focus distance from a position data of the condensing lens 4. By irradiating the detector 7 with a laser beam 2 and moving the beam condensing lens 4, a position data of the beam condensing lens 4 is stored at two points where detected values of the laser beam detector 7 show same, based on the two position data and position data of the laser beam detector 7, the focus distance is automatically detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus adjusting device for a laser processing machine for automatically adjusting the focus of laser light when performing laser processing.

[0002]

2. Description of the Related Art In recent years, laser processing machines have been widely used in the industrial field, but the problem of focus adjustment work is a problem.

A conventional focus adjusting device for a laser processing machine will be described below. If the condensing lens is replaced during laser processing, the focal position of the laser light changes. Japanese Patent Laid-Open No. 5-305471 discloses a numerical control database in which specific focal length data for each condenser lens is stored in advance in order to deal with such a case.
Disclosed is means for automatically moving the focus by an actuator that moves the position of the condenser lens corresponding to the selected condenser lens. However, when the lens is removed and the lens is cleaned, the focus position of the laser beam is slightly different from that before the removal even if the same lens is attached. As a means to deal with such a case and adjust the focus according to the actual state, the position of the stainless steel and the lens is changed while irradiating the stainless steel with the laser, and the position where a white spark called a blue frame occurs As disclosed in JP-A-59-73192 and JP-A-1-177005, a workpiece is irradiated with laser light, and the reflected light from the focus position And the size or area of the hole or slit actually processed as disclosed in Japanese Patent Laid-Open No. 220220/1990, and the position where these are minimum is set as the focus position. Means etc. are used.

[0004]

In the conventional focus adjustment method as described above, in the blue frame method, the operator makes visual judgments with his or her experience and intuition, resulting in individual differences in the focus position. Also, in the method of measuring the amount of reflected light or obtaining the focus position by imaging with the reflected light, the reflectance varies depending on the material of the work piece or the surface condition of the work piece, and proper reflected light cannot be obtained. In some cases, it is difficult to make accurate focus adjustment. Further, the means for measuring the machined hole requires actual machining, which makes the operation troublesome. In addition, if the focal position shift due to spherical aberration of the condenser lens is large, it cannot be processed at the position where the condensed diameter of the laser light is minimum unless focus adjustment is performed in consideration of the focal position shift. Efficiency and processing quality are reduced.

The present invention solves the above problems, has no human error, does not depend on the type of material to be processed, and does not require processing for actual processing. It is an object of the present invention to provide a focus position adjusting device for a laser processing machine capable of automatically setting the position to the optimum position.

[0006]

According to a first aspect of the present invention, there is provided a laser oscillator for outputting laser light, a condenser lens for condensing the laser light, and a condenser for controlling the movement of the condenser lens. A lens controller, a condenser lens driving device that moves the condenser lens under the control of the condenser lens controller, a laser light detector that detects the amount of laser light that has passed through the condenser lens, and the laser. A focus adjustment device for a laser processing machine, comprising a focal length calculation unit for calculating a focal length based on a detection value detected by a photodetector and position data of the condenser lens, and also according to claim 3. The present invention includes a laser oscillator that outputs laser light, a condenser lens that condenses the laser light, a condenser lens control unit that controls movement of the condenser lens, and a control of the condenser lens control unit. The condensing lens A condenser lens driving device for moving the laser beam, a laser light detector for detecting the amount of laser light passing through the condenser lens, and a detection value detected by the laser light detector and position data of the condenser lens. A focal length calculation unit that calculates the focal length based on this, a light shielding member that shields the peripheral portion of the laser light and can be attached and removed freely, and a minimum that calculates the minimum focusing distance that minimizes the focusing diameter of the laser light A focusing distance calculation unit, and based on the focal length with and without the light shielding member attached and the light diameter of the laser light in each case, It is a focus adjusting device for a laser processing machine, which is configured to calculate and obtain a focal length.

[0007]

In the present invention according to claim 1, the focal length calculation is performed based on the light amount detection value detected by the laser light detector, the position data of the condenser lens at that time, and the position data of the laser light detector. The department calculates the focal length and eliminates human error. Further, in the present invention according to claim 3, the light shielding member shields the laser light in the peripheral portion of the condenser lens, and the influence of the spherical aberration of the condenser lens is reflected in the change of the focal length.
Therefore, the focal length calculation unit calculates the focal length when the light blocking member is not set and the focal length when the light blocking member is set by the means according to claim 1, and the minimum focus distance calculation unit calculates From the focal length data, the position where the laser beam converges to the smallest radius is calculated as the minimum focusing distance.

[0008]

【Example】

(Embodiment 1) An embodiment of the focus adjusting device for a laser processing machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of this embodiment. In the figure, a laser beam 2 output from a laser oscillator 1 is guided to a laser torch 3, condensed by a condenser lens 4, and emitted toward a workpiece. The focus position of the laser beam 2 with respect to the workpiece is determined by the condenser lens control unit 5
Is controlled by driving the condensing lens driving device 6 to move the laser torch 3 in the vertical direction with respect to the workpiece. Further, the laser light detector 7 for detecting the laser light 2 is provided with a laser light detection surface horizontal and a laser torch 3
Install in the position of the horizontal movement range of. The focal length calculation unit 8 stores two pieces of position data of the condenser lens 4 when the detection values of the laser light detector 7 become the same value. From these two position data and the position data of the laser light detector 7, Calculate the focus position. FIG. 2 is a plan view showing the configuration of the laser photodetector in this embodiment. In the figure, three laser light detection elements 11a, 11b and 11c are provided at symmetrical positions on a ring-shaped laser light detector base 10 having a transmission hole 9 in the center. As these laser light detection elements,
An element such as a thermocouple that can convert energy of laser light into an electric signal is used.

Next, the procedure of the focus adjusting method will be described with reference to the drawings. 3 and 4 are side sectional views showing the focus adjustment operation of the present invention. The same components as those in FIG. 1 are assigned the same numbers. Laser light detector 7
The position data z0 of the detection surface is registered in the focal length calculation unit 8 in advance. The laser torch 3 is moved above the laser light detector 7 so that the optical axis of the laser light 2 coincides with the center of the laser light detector 7. In this case, since the laser light detector 7 is provided with three laser light detection elements at symmetrical positions, the optical axis of the laser light 2 is the center of the laser light detector 7 when the detection values of the respective detection elements match. Can be detected. The laser torch 3 is moved in the vertical direction while irradiating the laser light 2 to the laser light detector 7 in a state where the optical axes coincide with each other, and the focal length calculation unit 8 compares the detection value of the laser light detector 7 with a target value. This target value is the laser light detector 7
It may be any value within the range that the output of can take. When the detected value of the laser light detector 7 matches the target value, the focal length calculation unit 8 receives the position data z1 of the condenser lens 4 at that time from the condenser lens control unit 5 and stores it. FIG. 3 shows the positional relationship at this time. At this time, the laser light detector 7
When the target value is set to the minimum value at which the laser beam 2 can be detected, the laser beam 2 is transmitted through the transmission hole 9 of the laser beam detector 7 as shown in the figure.
And the detection value of the laser light detector 7 becomes the minimum, and it coincides with the target value.

Further, the laser torch 3 is moved in the direction perpendicular to the laser light detector 7 and the detected value of the laser light detector 7 is compared with the same target value as before. When the detection value of the laser light detector 7 matches the target value, the focal length calculation unit 8 causes the focusing lens control unit 5 to control the focusing lens 4 at that time.
It receives and stores the position data z2 of. FIG. 4 shows the positional relationship at this time. As shown in the figure, when the laser torch 3 is moved upward and the laser light 2 coincides with the transmission hole 9 of the laser light detector 7, the detection value of the laser light detector 7 is the minimum (from the minimum value This is the point at which the target value starts to increase), which matches the target value. In the focal length calculation unit 8, the two position data z1 and z2 of the condenser lens 4 when the detection values of the laser light detector 7 become the same value, and the laser light detector 7
The focal length L1 is calculated from the position data z0. Assuming that the distance between the midpoint between the two positions of the condenser lens 4 and the position of the laser light detector 7 is the focal length, the focal length L1 can be obtained as follows.

L1 = (z1 + z2) / 2-z0 The position of the laser torch 3 can be automatically set by the focal length data thus calculated.

As described above, according to this embodiment, the focal length can be calculated from the position data of the condenser lens where the laser light is the same and the position data of the laser light detector.
The focus position can be automatically set without causing a human error due to visual inspection.

In the above embodiment, the case where the position data in which the light amount of the laser light is the same is used is explained, but it is not always necessary to set the position in which the light amount is the same, and it is not necessary to set the position to the different position. It goes without saying that the focus position can be calculated from the light flux and the optical path by using the position data and the light amount data detected by the laser light detector at those positions. Further, instead of moving the laser torch 3, only the condenser lens 4 is moved, or the laser light detector 7 is moved.
It goes without saying that the same result can be obtained by moving only the focus adjustment work.

(Embodiment 2) An embodiment of the focus adjusting device for a laser beam machine according to the present invention will be described below with reference to the drawings. FIG. 5 is a block diagram showing the configuration of this embodiment. It should be noted that the same components as those in the first embodiment are given the same numbers and their explanations are omitted. The present embodiment is different from the first embodiment in that it includes a detachable light-shielding member 12 and a minimum focusing distance calculation unit 13, and if the focusing lens has spherical aberration, the position where the laser beam converges to the smallest radius. Is to calculate.

When the condenser lens 4 has spherical aberration, the focal position of the laser beam 2 varies depending on the position of the condenser lens 4,
Defocus position occurs. If the amount of deviation is large,
It is necessary to determine the minimum focusing distance that minimizes the focusing diameter of the laser light, considering the shift of the focal position. FIG. 5 is a block diagram showing a configuration of a focus position adjusting device for a laser processing machine in consideration of the minimum focusing distance. The same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In the figure, in the optical path from the condenser lens 4 to the laser light detector 7, the outer peripheral portion of the laser light 2 is shielded, and the light shield member 12 that can be attached and detached and the minimum beam distance is calculated from the two focal lengths. A minimum focusing distance calculation unit 13 is provided. Other components are the same as those in FIG.

FIG. 6 is a sectional view showing in detail the structure around the light shielding member. In the figure, R1 is the light diameter of the laser light 2 incident on the condenser lens 4, R2 is the diameter of the transmission hole of the light shielding member 12, and W is the attachment distance of the light shielding member 12 from the condenser lens 4. The shape of the transmission hole of the light shielding member 12 is preferably circular. Further, the light shielding member has a surface for shielding the laser light mounted horizontally, and the size of the transmission hole is set to be larger than that of the transmission hole 9 of the laser light detector 7.

The procedure of the focus position adjusting method will be described below with reference to the drawings. 7 and 8 are side sectional views showing the focus position deviation adjusting operation. First light blocking member 1
The focal length L1 is obtained by the above-mentioned method without providing 2. Next, as shown in FIG. 7, the light shielding member 12 is attached, the laser light 2 is applied to the laser light detector 7, and the laser torch 3 is moved in the vertical direction with respect to the laser light detector 7. The detection value of the detector 7 is compared with a predetermined target value, and when the detection value of the laser light detector 7 matches the target value, the focal length calculation unit 8 causes the focusing lens control unit 5
Then, the position data z3 of the condenser lens 4 at that time is received and stored. When the minimum value that can be detected by the laser light detector 7 is set as the target value, as shown in FIG. 7, when the laser light 2 coincides with the transmission hole 9 of the laser light detector 7, the laser light detector 7 The detected value becomes the minimum and matches the target value.

Further, as shown in FIG. 8, the detection value of the laser light detector 7 is compared with the target value while moving the laser torch 3 in the direction perpendicular to the laser light detector 7.
When the detected value of the laser light detector 7 matches the target value, the focal length calculation unit 8 receives the position data z4 of the condenser lens 4 at that time from the condenser lens control unit 5 and stores it. In the focal length calculation unit 8, two position data z3 of the condenser lens 4 when the detection value of the laser light detector 7 reaches the target value,
The focal length L2 is calculated from z4 and the position data z0 of the laser light detector 7. The distance between the midpoint between the two positions of the condenser lens 4 and the position of the laser light detector 7 is the focal length L2.
Then, the focal length L2 can be obtained as follows.

L2 = (z3 + z4) / 2-z0 If there is a shift in the focal position due to spherical aberration of the condenser lens 4 or the like, the two focal lengths L1 and L2 obtained by the above procedure differ. FIG. 9 shows the shift of the focal length due to such spherical aberration. In the condensing lens 4 formed of a spherical surface, the focal length becomes shorter as the laser light passes through the outside.

The minimum focusing distance calculation unit 13 calculates the minimum focusing distance by the following procedure. In FIG. 9, R3 is the light diameter of the laser light that can pass through the light blocking member 12 (the diameter of the laser light before entering the condenser lens 4) when the light blocking member 12 is attached. Transmission hole diameter R2,
The value of R3 can be obtained from the mounting distance W by the following equation.

R3 = L2R2 / (L2-W) As shown by A and B in FIG. 9, two laser beams when the light shielding member is attached and after it is removed after passing through the condenser lens 4 There are two points where the outer edges of the cross. Of these two intersections A and B, the intersection B located at a position far from the condenser lens 4 is the position where the condensed diameter of the laser light 2 after passing through the condenser lens 4 is the smallest. The minimum focusing distance L3 from the focusing lens 4 to the minimum focusing position is the laser beam diameter R1 when the light shielding member is not provided, the laser beam diameter R3 when it is not provided, and the focal lengths L1 and L2 in each case. It can be easily obtained from and is as follows.

L3 = L1 · L2 · (R1 + R3) / (R1 · L2 + R3 · L
1) The laser torch 3 can be automatically set at the position where the laser beam converges to the minimum by the data of the minimum focusing distance calculated in this way.

As described above, according to the focus adjusting device for a laser beam machine of this embodiment, the influence of the spherical aberration of the condenser lens is detected as the change of the focal length by using the light shielding member, and the light shielding member is set. In this case, the position where the laser light converges to the minimum can be automatically calculated and set as the minimum converging distance from the focal length data and the laser light diameter in the case where it is not set.

In the present embodiment as well, the means for calculating the focal length using the position data having the same light amount has been described, but as described in the first embodiment, the position data having the same light amount is limited. Needless to say, instead of moving the laser torch 3, the condenser lens 4
The same result can be obtained by moving only the laser light detector 7 or moving only the laser light detector 7 and setting the position of the light shielding member in the optical path in front of the condenser lens 4. It goes without saying that you can do it.

[0025]

As is apparent from the above description, the present invention according to claim 1 is directed to a laser oscillator for outputting laser light, a condenser lens for condensing the laser light, and a movement of the condenser lens. A condensing lens control unit, a laser light detector that detects the amount of laser light that has passed through the condensing lens, a detection value detected by the laser light detector, and position data of the condensing lens. Since the focal length calculation unit that calculates the focal length based on it is provided, the focal length can be calculated numerically based on the light amount detected by the laser light detector and the condenser lens position data at that time. It can be set without including human error.

Further, the present invention according to claim 3 is a laser oscillator for outputting a laser beam, a condenser lens for condensing the laser beam, and a condenser lens control section for moving the condenser lens. A laser light detector that detects the amount of laser light that has passed through the condenser lens, and a focal length that calculates a focal length based on the detection value detected by the laser light detector and the position data of the condenser lens. A calculation unit, a light-shielding member that shields the peripheral portion of the laser light, and can be attached and detached freely, and a minimum focusing distance calculating unit that calculates the minimum focusing distance that minimizes the focusing diameter of the laser light, Based on the focal lengths of the case where the light shielding member is not attached and the case where the light shielding member is attached, and the light diameter of the laser light in each case, the minimum light collecting distance that minimizes the light collecting diameter of the laser light is calculated and obtained. By doing so, The distance and the minimum convergence distance at which the laser light converges to the minimum can be calculated and set automatically, the influence of spherical aberration can also be excluded, and the correct focus position can be set automatically, eliminating human setting errors. be able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a focus adjusting device for a laser beam machine according to the present invention.

FIG. 2 is a plan view showing the configuration of a laser photodetector in an embodiment of the focus adjusting device for a laser beam machine of the present invention.

FIG. 3 is a side sectional view for explaining the operation of the embodiment of the focus adjusting device for a laser beam machine of the present invention.

FIG. 4 is a side sectional view for explaining the operation of an embodiment of the focus adjusting device for a laser beam machine of the present invention.

FIG. 5 is a block diagram showing a configuration of an embodiment for obtaining a minimum focusing distance in the focus adjusting device for a laser beam machine of the present invention.

FIG. 6 is a side sectional view showing a configuration around a light shielding member in a focus adjusting device for a laser beam machine according to the present invention.

FIG. 7 is a side sectional view for explaining the operation when the minimum focusing distance is obtained in the focus adjusting device for a laser beam machine of the present invention.

FIG. 8 is a side sectional view for explaining the operation when obtaining the minimum focusing distance in the focus adjusting device for a laser beam machine of the present invention.

FIG. 9 is a side sectional view showing a focal length shift caused by spherical aberration.

[Explanation of symbols]

 1 Laser Oscillator 2 Laser Light 3 Laser Torch 4 Condensing Lens 5 Condensing Lens Control Unit 6 Condensing Lens Driving Device 7 Laser Light Detector 8 Focal Length Calculation Unit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuichi Uchida 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. A laser oscillator that outputs laser light, a condenser lens that condenses the laser light, a condenser lens control unit that moves the condenser lens, and a laser that passes through the condenser lens. A laser light detector that detects the amount of light,
A focus adjustment device for a laser processing machine, comprising: a focal length calculation unit that calculates a focal length based on a detection value detected by the laser light detector and position data of the condenser lens. 2. The focal length calculation unit stores two different position data of the condenser lens when the detection value of the laser light detector becomes the same value, and the two position data and the laser light detector are stored. The focal length is calculated based on the position data.
A focus adjusting device for the laser processing machine described. 3. A laser oscillator that outputs laser light, a condenser lens that condenses the laser light, a condenser lens control unit that moves the condenser lens, and a laser that passes through the condenser lens. A laser light detector that detects the amount of light,
A focal length calculation unit that calculates the focal length based on the detection value detected by the laser light detector and the position data of the condenser lens, and a light shielding member that shields the peripheral portion of the laser light and can be attached and detached freely. And a minimum condensing distance calculation unit that calculates a minimum condensing distance that minimizes the condensing diameter of the laser light, and a focal length when the light shielding member is not attached and when the light shielding member is attached, and a laser in each case. A focus adjustment device for a laser processing machine, which calculates and obtains a minimum focusing distance that minimizes the focusing diameter of laser light based on the light diameter of light.