CN101314195A - Optical focus compensation method of laser cutting device - Google Patents

Abstract

A light focus compensation method of a laser cutting device comprises a laser oscillation generator, a reflecting mirror, a focusing mirror, a digital controller, a driver and a processing carrying platform, wherein the reflecting mirror is arranged on a beam path emitted by the laser oscillation generator, the focusing mirror is arranged on the laser beam path reflected by the reflecting mirror and is configured on the processing carrying platform, and the carrying platform is connected with the driver and the digital controller and is controlled by the digital controller to move the position of the carrying platform through the driver; the optical focus compensation method comprises the following steps: obtaining a curve chart of the change of the size of the light spot of the laser oscillation generator in advance; establishing a reference data to simulate the curve chart, and inputting the reference data into a digital controller as a comparison database; moving the focusing lens carried by the processing carrying platform to different positions, corresponding to the numerical value of the reference data, and calculating the variation of the focusing point of the focusing lens by a numerical controller; the digital controller sends out command to the driver to change the position of the focusing lens on the carrier to compensate the error of the light focus caused by the change of the divergence angle of the laser beam.

Description

Optical focus compensation method of laser cutting device

technical field

The present invention relates to an optical focus compensation method for a laser cutting device, in particular to an optical focus compensation method for a laser cutting device that utilizes the optical focus compensation method to improve the size error of the final product due to changes in the divergence angle of the laser beam.

Background technique

Laser (Laser) is a new term of science and technology in the past 20 years. The application of its technology has continuously achieved breakthroughs, including outstanding contributions to industrial processing types, such as drilling, cutting, welding and heat treatment of various materials.

With the increase of the laser processing field, the laser is required to gradually develop from a low power level to a high power level. Taking cutting processing as an example, the thickness of the object to be cut is increasing, and the required cutting section quality and accuracy must be maintained; therefore, how to more accurately control the stability of the laser beam to achieve high-standard processing quality is a key issue for all laser cutting applications. The manufacturer of the device has been working hard.

Taking Figure 1 as an example, the general laser beam is emitted after being generated by an oscillator. Due to the change in the divergence angle of the beam, the received ranges at different positions of the same optical path are not consistent, as shown in the mirrors 10 and 11 at positions P1 and P2. , because the difference of the laser reflection diameters R1 and R2 directly affects the position of the rear end focus; that is, the focusing lens groups 12, 13 arranged under the same physical property conditions, the resulting depth of focus (DOF) F1, F2 will have The change of misalignment finally causes the deviation between the position where the laser is actually loaded on the object and the predetermined path or depth as shown in Figure 2, which causes considerable trouble for the operator. In particular, equipment with larger strokes, or cutting with thicker workpieces will have a greater impact; if the problem of laser divergence angle changes is not improved, the resulting cutting quality will be inconsistent, which will eventually lead to dimensional errors in the finished product increase and it is difficult to control the quality.

In order to solve the above problems, the industry has successively developed some improvement plans. The "equal-length design of the optical path" shown in Figure 3, the "Use of the telescope group to reduce the laser divergence angle (TELESCOPECOUPLER)" shown in Figure 4, or the "ADAPTIVE MIRROR" disclosed in Figure 5 and other technologies ; but many of them still have the defects listed below:

(1) The disadvantages of "equal-length optical path design" are:

(1) The mechanism is relatively complicated and the required cost is high, so it is not suitable for large-travel beds;

(2) There are two more mirror groups 15, 16, which will increase the maintenance cost in the future;

(3) The beam path generated by the laser oscillator 1 has one more turning point, and two reflector groups 15, 16 are added, so that the difficulty of optical path correction is relatively increased;

(4) There are two more reflector groups 15, 16, and they must move synchronously with the carrier of the cutting device, which is not suitable for high-speed cutting machine tools.

(2) "Using the telescope group to reduce the laser divergence angle (TELESCOPE COUPLER)" mainly installs a concave-convex mirror group 17, 18 in the beam path generated by the laser oscillator 1, arranged in a "Z" shape to reduce the Laser divergence angle; its disadvantages are:

(1) The specifications of the concave-convex lens groups 17, 18 must be designed in accordance with the position of the waist of the laser beam (WAIST) and the size of the processing range. The configuration cost is expensive, and because it is a non-standard lens element, the future maintenance and consumption expenses are very considerable;

(2) The influence caused by the change of the laser divergence angle cannot be completely eliminated, and the quality and size errors of the far and near processing points of the large bed cannot be improved, and it is not applicable when the size of the bed is larger than 2M*4M;

(3) Because a group of concave-convex mirrors are installed in the device, the optical path correction work is more difficult.

(3) "ADAPTIVE MIRROR" mainly uses hydraulic or pneumatic control to change the surface curvature of the mirror 19, so that the same spot size is generated when cutting at different optical path positions, and is used to stabilize the laser cutting. Quality and reduce the dimensional error of the finished product; its disadvantages are:

(1) The variable curvature mirror group 19 is a reflector, which is expensive, and the normal consumption and maintenance costs in the future are very considerable, about 20 times higher than the general standard reflector group;

(2) The accuracy of laser optical path correction and the requirements for center alignment are relatively high, otherwise the variable surface of the mirror group will cause greater deviation of the optical path;

(3) The error of the variable curvature of the lens group will vary with conditions such as ambient temperature, lens surface cleanliness, and laser power, which will increase the difficulty of control and will eventually affect the size of the final spot.

In addition, prior technical documents such as laser cutting applications, including U.S. Patent Nos. 5,690,785, 5,783,814, and 5,594,235, although discussing dynamic focusing technology and/or related focal point depth issues, have nothing to do with "laser divergence". The concept of "angle change" is used to improve the impact of the resulting error.

Contents of the invention

The object of the present invention is to provide an optical focus compensation method for a laser cutting device, so as to improve the error in the size of the final product due to the change in the divergence angle of the laser beam.

The optical focus compensation method provided by the present invention is realized in the following steps:

(1) Obtain in advance the graph of the change in spot size or the change in the divergence angle of the beam shown by the laser oscillator generator in a stable length range after generating the beam mode;

(2) Establish a "reference data" to simulate the aforementioned curves, and input the "reference data" into the CNC as a database for comparison;

(3) According to the focusing lens carried on the processing platform, it is moved to different positions, corresponding to the value of the aforementioned "reference data", and the numerical control calculates the variation of the focus point of the focusing lens;

(4) The CNC sends an instruction to the driver to change the position of the focusing mirror on the stage to compensate for the error of the optical focus due to the change in the divergence angle of the laser beam.

The present invention provides an optical focus compensation method for a laser cutting device. The device includes a laser oscillation generator, a reflection mirror, a focusing mirror, a numerical control, a driver, and a processing stage, wherein the reflection mirror is arranged on the laser oscillation generator. On the path of the emitted beam, the focusing mirror is set on the path of the laser beam reflected by the mirror, and is arranged on the processing stage. The processing stage is connected with the driver and the numerical control, and is controlled by the numerical control to move the position of the processing stage by the driver. ; The optical focus compensation method is:

(1) Obtain in advance the graph of the change in spot size or the change in the divergence angle of the beam shown by the laser oscillator generator in a stable length range after generating the beam mode;

(2), set up a reference data to simulate the aforementioned curve diagram, and input the reference data into the numerical control device as a database for comparison;

(3) Move to different positions according to the focusing mirror carried on the processing platform, corresponding to the numerical value of the aforementioned reference data, and calculate the variation of the focal point of the focusing mirror by the numerical control device;

(4) The CNC sends an instruction to the driver to change the position of the focusing mirror on the stage to compensate for the error of the optical focus due to the change in the divergence angle of the laser beam.

Advantages of the present invention over prior art include:

1. In the processing technology of laser cutting, the processing quality of the whole stroke and the stability of the dimensional accuracy of each processed product can be obtained, especially when applied to the cutting environment with large stroke or high power, the effect obtained is more significant.

2. The overall design is simple, and there is no need to greatly modify the optical components and structural design to reduce maintenance costs.

3. There is no need to add additional optical lenses in the device to save costs and maintenance of consumables in the future.

4. There is no need to change the existing laser light path calibration procedure, making the operation easier.

5. The scope of application and compatibility of the device are large, and laser oscillator generators of various brands can be used in the cutting process technology of the present invention.

Description of drawings

Fig. 1 is a processing configuration diagram of a conventional laser cutting device.

FIG. 2 is a comparison diagram of the deviation between the position where the laser is actually loaded on the object and the predetermined path or depth.

Fig. 3 is a processing configuration diagram of an existing "equal-length optical path design" laser cutting device.

Fig. 4 is a processing configuration diagram of an existing laser cutting device "using a telescope group to reduce the laser divergence angle".

Fig. 5 is a processing configuration diagram of the existing "variable curvature mirror group" laser cutting device.

Fig. 6 is a processing flowchart of the laser cutting device of the present invention.

Fig. 7 is a processing configuration diagram of the laser cutting device of the present invention.

Explanation of main component symbols

2...Laser oscillator generator 20...Laser beam

3...reflector 30...laser beam path

4, 4a... Focusing mirror 5, 5a... Object to be processed

6...Numerical Control Unit 7...Driver

8...Processing platform 50...Working table

Detailed ways

As shown in Figure 6, the laser cutting device of the present invention includes:

A laser oscillation generator 2, used to generate a certain range of laser beams 20;

A reflector 3, which is arranged on the path of the laser beam 20 emitted by the laser oscillation generator 2, for reflecting the laser beam to a predetermined position;

Focusing mirror 4, the focusing mirror 4 is placed on the processing stage 8, and the focusing mirror 4 is positioned on the laser beam path 30 reflected by the aforementioned reflector 3 through the movement of the stage 8, and the beam is gathered by the focusing mirror 4 corresponding to the object to be processed 5 for cutting;

A numerical control device 6, such as a CNC (Computer Numerical Control) computer numerical controller, has a built-in database for connecting the driver 7 and controlling the driver 7 to act;

The driver 7 is used to connect the processing stage 8 and drive the stage to move;

Processing stage 8 for carrying focusing lens 4;

The optical focus compensation method of the present invention is:

1. Obtain in advance the graph of the change in spot size or the change in the divergence angle of the beam shown by the laser oscillator generator 2 in a stable length range after generating the beam mode;

2. Establish a "reference data" to simulate a quadratic equation that matches the aforementioned graph, and input the "reference data" into the numerical control device 6 as a database for comparison;

3. According to the movement of the focusing lens 4 carried by the processing platform 8 to different positions, corresponding to the value of the aforementioned "reference data", the numerical control device 6 calculates the variation of the focus point of the focusing lens 4;

4. The numerical control 6 sends an instruction to the driver 7 to change the position of the focusing mirror 4 on the stage 8 to compensate for the error of the optical focus due to the change in the divergence angle of the laser beam.

More specifically, taking the implementation state of FIG. 7 as an example, objects to be processed 5, 5a are placed on the workbench 50. After the laser oscillation generator emits a laser beam 20 within a certain range, due to the divergence angle of the beam 20 changes, The ranges received at different positions of the same optical path are not consistent. Reflectors 3 and 3a at different positions away from laser oscillator generators A1 and A2 as shown in the figure, because of the difference in laser reflection diameters θ1 and θ2, the focus depth produced by focusing lens groups 4 and 4a arranged under the same physical property conditions ( DOF) C1 and C2 will have ectopic changes; therefore, through the aforementioned optical focus compensation method: in the database of the CNC numerical control device 6, the "reference data" that matches the change curve of the laser divergence angle is pre-established, and according to each The position of the processed object 5, 5a is accurately calculated by the aforementioned "reference data" of the received laser beam diameters θ1 and θ2, and the change between the focus points is converted by the focusing lens 4, 4a with the same physical property conditions measure δ, and then store the obtained value in the database of the CNC numerical control device 6; When the stage 8 is driven by the driver 7 at A2, its position must be changed according to the delta variation calculated previously, so as to compensate possible focusing errors at the rear end.

Finally, through the processing and sampling of the actual position, the finished product size of each sampling position is measured, and the error of the compensation value is further corrected to obtain a more accurate compensation; the more sampling positions, the relatively consistent with the laser divergence angle change curve. The error of the "reference data" will also be more convergent.

The inventor actually tested according to the above method, adding to the processing range of stroke 2M*4M and 2M*6M, the dimensional error is only about 0.05mm (take 16mm thick steel plate as an example), and the range of optical focus compensation of the focusing mirror, Only changing within 0-2.4mm can indeed achieve the desired goal.

However, the above descriptions are only preferred implementation modes of the present invention, and certainly cannot limit the scope of rights of the present invention. All equivalent modifications or changes made by those skilled in the art according to the spirit of the present invention are still within the scope of rights of the present invention.

Claims (8)

1, a kind of smooth focal compensation process is characterized in that, may further comprise the steps:

(1), in advance obtain laser generation generator one section curve map that the stable spot size that length range showed changes after producing light beam mode, or the curve map of beam divergence angle size variation;

(2), set up a reference data and simulate aforesaid curve map, and with the database of this reference data input digital control implement as comparison;

(3), move to diverse location according to processing microscope carrier contained focus lamp, the numerical value of corresponding above-mentioned reference data, and calculate the variable quantity of the focus point of this focus lamp by digital control implement;

(4), send instruction by digital control implement and change the error that the focus lamp position on the microscope carrier is produced because of the laser beam divergent angle size variation with compensation light Jiao to driver.

2, smooth focal compensation process as claimed in claim 1 is characterized in that, described smooth focal compensation process also comprises step:

(5), take a sample by the processing of physical location, measure the finished size of each sample position, the error of offset is done further to revise, compensate more accurately obtaining, sample position point the more, the error of the reference data of the laser beam divergence size variation curve that coincide relatively also can more restrain.

3, smooth focal compensation process as claimed in claim 1 or 2 is characterized in that, described digital control implement is the computer numerical controller.

4, smooth focal compensation process as claimed in claim 1 or 2 is characterized in that, described reference data is the quadratic equation with one unknown formula.

5, a kind of light focal compensation process of laser cutting device, this device comprises laser generation generator, speculum, focus lamp, digital control implement, driver and processing microscope carrier, wherein, this speculum is located on the laser generation generator institute emitted light beams path, focus lamp is located on the laser beam path after the mirror reflects, and be disposed at the processing microscope carrier, this processing microscope carrier links to each other with driver and digital control implement, is subjected to digital control implement control to move processing microscope carrier position with driver; It is characterized in that this light focal compensation process is:

(1), in advance obtain laser generation generator one section curve map that the stable spot size that length range showed changes after producing light beam mode, or the curve map of beam divergence angle size variation;

(2), set up a reference data and simulate aforesaid curve map, and with the database of this reference data input digital control implement as comparison;

(3), move to diverse location according to processing microscope carrier contained focus lamp, the numerical value of corresponding above-mentioned reference data, and calculate the variable quantity of the focus point of this focus lamp by digital control implement;

(4), send instruction by digital control implement and change the error that the focus lamp position on the microscope carrier is produced because of the laser beam divergent angle size variation with compensation light Jiao to driver.

6, the light focal compensation process of laser cutting device as claimed in claim 5 is characterized in that, described smooth focal compensation process also comprises step:

(5), take a sample by the processing of physical location, measure the finished size of each sample position, the error of offset is done further to revise, compensate more accurately obtaining, sample position point the more, the error of the reference data of the laser beam divergence size variation curve that coincide relatively also can more restrain.

As the light focal compensation process of claim 5 or 6 described laser cutting devices, it is characterized in that 7, described digital control implement is the computer numerical controller.

As the light focal compensation process of claim 5 or 6 described laser cutting devices, it is characterized in that 8, described reference data is the quadratic equation with one unknown formula.

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