A dynamic optical path compensation control method of a three-dimensional laser cutting machine

Abstract

This invention discloses a dynamic optical path compensation control method for a three-dimensional laser cutting machine, including a continuous dynamic optical path compensation control method and a segmented dynamic optical path compensation control method. The PLC controller calculates the variable optical path S by acquiring the real-time position information of the motion mechanism in the cutting machine tool. t and the variable optical path change ΔS; determine the target air pressure P in the curvature mirror based on the variable optical path change ΔS. 目 The PLC controller outputs air pressure regulation commands to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror in the opposite direction to the target air pressure P. 目 This invention enables dynamic adjustment of the curvature of the curvature mirror, thereby maintaining the beam diameter reaching the focusing lens at the target beam diameter R3. The invention utilizes a dynamic optical path control system to dynamically regulate the original beam diameter in a 3D laser cutting machine, ensuring the stability of the target beam diameter and focal position transmitted to the laser cutting head. This method offers precise control, rapid response, and guarantees product performance.

Description

Technical Field

[0001] This invention relates to the field of optical path control technology for laser cutting equipment, specifically a dynamic optical path compensation control method for a three-dimensional laser cutting machine based on a variable curvature mirror. Background Technology

[0002] In existing technologies, 3D laser cutting equipment is commonly used for cutting various materials such as metals, non-metals, and new composite materials. Due to the excellent performance of laser cutting, laser cutting equipment has been widely used. At the same time, new application scenarios have also placed higher demands on 3D laser cutting equipment. In order to achieve better processing performance, the development of 3D cutting equipment with larger processing area and faster processing speed is the direction of technological development. However, the increase in processing area and speed usually leads to a decrease in laser cutting quality, such as uneven kerf width and rough cutting edges. The main reason for the quality problems is that when the processing area of ​​the laser processing equipment increases, the optical path of the built-in optical path system of the equipment usually also becomes longer. The divergence angle of laser transmission makes the beam diameter change more significantly after the laser passes through a longer optical path. The increase in processing speed makes the dynamic position of the moving components in the 3D cutting equipment change more rapidly, and the optical path in the optical path system also changes rapidly. This makes the changes in the optical performance of the laser beam during the operation of the equipment more complex. For example, the optical performance of the laser beam transmitted to the cutting head through the fast dynamic optical path system is very unstable. The beam diameter and focal position will fluctuate, which will reduce the laser cutting quality and even cause the cut workpiece to be scrapped. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a dynamic optical path compensation control method for a three-dimensional laser cutting machine based on a variable curvature mirror. Specifically, two dynamic optical path compensation control methods are provided: the first is a continuous dynamic optical path compensation control method, and the second is a segmented dynamic optical path compensation control method.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A dynamic optical path compensation control method for a three-dimensional laser cutting machine is disclosed. This control method can be used for dynamic optical path compensation control of a three-dimensional laser cutting machine, which consists of a laser, a cutting machine tool, and a dynamic optical path control system.

[0006] The laser is used to generate a laser beam, which is guided by a light guide tube from one end of the cutting machine tool into the machine tool body.

[0007] The dynamic optical path control system includes a PLC controller, a curvature control unit, a curvature mirror, and a plane reflector.

[0008] The PLC controller is connected to the CNC machine tool control center to obtain real-time position information of the motion mechanism on the 3D laser cutting machine from the CNC machine tool control center, and to calculate the variable optical path S. t The motion mechanism includes a cantilever, a Z-axis assembly, and a laser cutting head.

[0009] The curvature control unit includes a numerically controlled proportional valve, an air supply mechanism, and a pressure sensor. The air supply mechanism precisely supplies air to the curvature mirror via the numerically controlled proportional valve, adjusting the curvature of the mirror by adjusting the air pressure. The pressure sensor is used to collect the real-time air pressure P in the curvature mirror. 实 The data is then fed back to the PLC controller for real-time monitoring of the air pressure in the curvature mirror.

[0010] The curvature mirror is a variable curvature reflector. The curvature mirror can change the beam diameter by adjusting the curvature. The beam diameter after reflection by the curvature mirror can continuously change within the curvature adjustment range, so that the beam diameter when the laser beam is transmitted to the target position is controllable.

[0011] The curvature adjustment principle of a curvature mirror: The inside of a curvature mirror is a hollow cavity. The reflective surface of the curvature mirror is made of flexible material. Gas is filled into the hollow cavity inside the curvature mirror. As the internal air pressure changes, the flexible surface of the curvature mirror will deform. As the air pressure increases, the curvature mirror will gradually change from a concave mirror to a plane mirror and then to a convex mirror. The curvature of the curvature mirror changes linearly with the air pressure.

[0012] The cutting machine tool includes a machine body, a cantilever, and a Z-axis assembly. A laser cutting head is located at the end of the Z-axis assembly. An optical path system is constructed by installing multiple optical lenses within the machine tool. The laser beam is sequentially transmitted through the machine body and cantilever to the laser cutting head at the end of the Z-axis assembly, and finally output from the laser cutting head to cut the workpiece. This optical path system is controlled by a dynamic optical path control system. Using the optical lenses as dividing points, the optical path can be divided into at least four segments:

[0013] Fixed optical path: The laser beam generated by the laser is output from the window mirror, then guided into the machine tool body by the light guide tube. After being transmitted through the optical path, it is incident on the curvature mirror. The curvature mirror is fixedly connected to the machine tool body. The section of the optical path between the window mirror and the curvature mirror is the fixed optical path. A plane mirror can be added before the beam is incident on the curvature mirror to change the direction of the optical path, but the length L0 of the fixed optical path remains unchanged. Generally, 0 < L0 ≤ 1m.

[0014] First dynamic optical path: After being reflected by the curvature mirror, the laser is transmitted along the length of the machine tool body and incident on the first plane mirror at one end of the cantilever. The cantilever will drive the first plane mirror to move back and forth on the machine tool body along the Y-axis. The position of the first plane mirror will change continuously, and the length of the optical path between the curvature mirror and the first plane mirror will also change continuously. This optical path is the first dynamic optical path, and the optical path length is L1, where L1 is a variable.

[0015] Second dynamic optical path: After being reflected by the first planar reflector, the laser is transmitted along the length of the cantilever and incident on the second planar reflector on the Z-axis assembly. The Z-axis assembly will drive the second planar reflector to move back and forth along the X-axis on the cantilever. The position of the second planar reflector will change continuously, and the length of the optical path between the first and second planar reflectors will also change continuously. This optical path is the second dynamic optical path, and the length of the optical path is L2, where L2 is a variable.

[0016] The third dynamic optical path: After being reflected by the second plane mirror, the laser is transmitted downward along the length of the Z-axis assembly and incident on the focusing lens in the laser cutting head. The Z-axis assembly drives the laser cutting head to move back and forth along the Z-axis. The position of the focusing lens will change continuously, and the length of the optical path between the second plane mirror and the focusing lens will also change continuously. This optical path is the third dynamic optical path, and the length of the optical path is L3. L3 is a variable, and generally L3≤0.6m.

[0017] In the three-dimensional laser cutting machine provided by this invention, the laser is output from the window mirror of the laser device. The laser beam at the window mirror is called the initial beam, and the diameter R1 of the initial beam is stable. The laser is reflected sequentially by a curvature mirror, a first plane mirror, and a second plane mirror before entering the focusing mirror in the laser cutting head. The original beam diameter at the incident surface of the focusing mirror is R2. The total optical path length L between the window mirror and the focusing mirror is: L = L0 + L1 + L2 + L3, where the length L0 of the fixed optical path is fixed and constant, while the lengths L1 of the first dynamic optical path, L2 of the second dynamic optical path, and L3 of the third dynamic optical path change continuously during the operation of the three-dimensional laser cutting machine, which is reflected as the real-time length L of the first dynamic optical path. 1t The real-time length L of the second dynamic optical path 2t The real-time length L of the third dynamic optical path 3t Therefore, the total optical path length L will also change continuously, which is reflected in the real-time total optical path length L. t For: L t =L0+L 1t +L 2t +L 3t Because laser transmission has a divergence angle, the beam diameter gradually increases during transmission. Therefore, R2 > R1, and the total real-time optical path length L... tAs the beam size increases, the original beam diameter R2 also increases, and the total real-time optical path length L... t As the diameter of the original beam decreases, the diameter of the original beam R2 also decreases. Therefore, the diameter of the original beam R2 at the incident surface of the focusing lens will continuously change during the operation of the 3D laser cutting machine. This change in the original beam diameter R2 negatively impacts the laser cutting quality. Because a laser beam with an original diameter of R2, after being focused by the focusing lens, will form a target beam with a diameter of R3 and a focal length of f to perform laser cutting on the workpiece, the diameters of the target beam R3 and the focal length f will also change with the change in the original beam diameter R2. Changes in the target beam diameter R3 will lead to uneven kerf width, and changes in the focal length f will lead to instability in the focal position of the focused beam. Consequently, the laser beam cannot be accurately focused on the cutting surface of the workpiece. This instability in the focal position not only leads to uneven kerf but also to quality problems such as rough kerf edges. Therefore, to obtain stable laser cutting quality, it is necessary to maintain the stability of the target beam diameter R3 and the focal length f as much as possible. The stability of the target beam diameter R3 and the focal length f depends on the stability of the original beam diameter R2. The change in the original beam diameter R2 is due to the change in the total real-time optical path length L in the dynamic optical path. t The constant changes in the total length L of the optical path in a 3D laser cutting machine, caused by the operation of the motion mechanism, result in a real-time variation. t Changes are also unavoidable. To ensure the total real-time optical path length L... t The present invention achieves the technical effect of stabilizing the original beam diameter R2 under changing conditions. The dynamic optical path compensation control method provides dynamically adjusts the beam diameter after reflection by adjusting the curvature of the curvature mirror, so that the beam diameter changes with the real-time total optical path length L. t The change is based on the principle that the diameter R2 of the original laser beam transmitted to the incident surface of the focusing lens should remain stable within the error range.

[0018] Based on the aforementioned three-dimensional laser cutting machine, this invention provides two dynamic optical path compensation control methods: the first is a continuous dynamic optical path compensation control method, and the second is a segmented dynamic optical path compensation control method, which are described below.

[0019] A dynamic optical path compensation control method for a three-dimensional laser cutting machine is disclosed. This method is a continuous dynamic optical path compensation control method, and the specific steps are as follows:

[0020] A. The PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool and calculates the variable optical path S at time t. t And obtain the variable optical path change ΔS=S when the time interval is ΔT. t -S t-1 When ΔS≠0, proceed to step B;

[0021] B. The PLC controller determines the target air pressure P in the curvature mirror based on the variable optical path change ΔS. 目 P 目 =P 实 +ΔP, and the value of the pressure change ΔP is a negative number equal to half the value of the variable optical path change ΔS. 实 This represents the real-time air pressure within the current curvature mirror.

[0022] C. The PLC controller outputs air pressure regulation commands to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror in the opposite direction to the target air pressure P. 目 This enables dynamic adjustment of the curvature of the curvature mirror, thereby maintaining the beam diameter reaching the focusing mirror at the target beam diameter R3, with an error range of ±0.1mm for the target beam diameter R3.

[0023] The time interval ΔT for the PLC controller to acquire the real-time position information of the motion mechanism in the cutting machine tool in step A is 10ms.

[0024] A dynamic optical path compensation control method for a three-dimensional laser cutting machine is disclosed. This method is a segmented dynamic optical path compensation control method, and the specific steps are as follows:

[0025] A. The PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool and calculates the variable optical path S at time t. t And obtain the variable optical path change ΔS=S t -S min When ΔS≠0, proceed to step B;

[0026] B. The PLC controller directly determines the target air pressure P based on the optical path range in which the variable optical path change ΔS falls. 目 ;

[0027] C. The PLC controller compares the real-time air pressure P in the curvature mirror. 实 and target air pressure P 目 When P 实 =P 目 When P returns to step A, 实 ≠P 目 At that time, proceed to step D;

[0028] D. The PLC controller outputs an air pressure regulation command to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror in the opposite direction to the target air pressure P. 目 This enables dynamic adjustment of the curvature of the curvature mirror, thereby maintaining the beam diameter reaching the focusing lens at the target beam diameter R3, with an error range of ±0.5mm for the target beam diameter R3.

[0029] The target air pressure P in step B 目The method for determining it is as follows:

[0030] B1. The maximum value ΔS of the variable optical path change. max Divide into n equal parts, according to ΔS max The pattern is divided into (n+1) optical path ranges;

[0031] B2. Determine the maximum value ΔS of the variable optical path change. max Minimum target air pressure P at that time min目 The value of the target air pressure, or the maximum value P when the variable optical path change ΔS = 0. max目 The value;

[0032] B3. According to the rule that the optical path range corresponding to the variable optical path change ΔS increases from small to large, the target air pressure P corresponding to each optical path range... 目 The value is determined by the maximum target air pressure P. max目 The values ​​are according to The value decreases; or according to the law that the optical path range corresponding to the variable optical path change ΔS decreases from large to small, the target air pressure P corresponding to each optical path range. 目 The value is determined by the minimum target air pressure P. min目 The values ​​are according to The value increases.

[0033] In step C, the time interval for the PLC controller to acquire the real-time position information of the motion mechanism in the cutting machine tool is 1000ms.

[0034] The PLC controller uses a pressure sensor to collect the real-time air pressure P in the curvature mirror. 实 The PLC controller will monitor the real-time air pressure P 实 The numerical value and target air pressure P 目 The values ​​of P are compared multiple times. 实 >P 目 If the abnormal status persists for more than the set time, the PLC controller will send the abnormal information to the machine tool control center, which will then issue an alarm and suspend the cutting operation.

[0035] The PLC controller uses a pressure sensor to collect the real-time air pressure P in the curvature mirror. 实 The PLC controller will monitor the real-time air pressure P 实 The numerical value and target air pressure P 目 The values ​​of P are compared multiple times. 实 <P 目 If the abnormal status persists for more than the set time, the PLC controller will send the abnormal information to the machine tool control center, which will then issue an alarm and suspend the cutting operation.

[0036] The aforementioned setting time is generally 10ms or 20ms for continuous dynamic optical path compensation control methods; and generally 1000ms for segmented dynamic optical path compensation control methods.

[0037] The PLC controller uses a pressure sensor to collect the real-time air pressure P in the curvature mirror. 实 When P 实 >P max Time, or P 实 <P min When this happens, the PLC controller will send the abnormal information to the machine tool control center, which will then issue an alarm and suspend the cutting operation.

[0038] The curvature control unit includes an air supply mechanism, a numerically controlled proportional valve, and a pressure sensor. The air supply mechanism supplies air to the curvature mirror through the numerically controlled proportional valve. The numerically controlled proportional valve is connected to a PLC controller via a circuit to receive and execute air pressure regulation commands issued by the PLC controller. The pressure sensor is connected to the PLC controller via a circuit to collect the real-time air pressure P in the curvature mirror. 实 And then feed back to the PLC controller.

[0039] The variable optical path S t The sum of the first dynamic optical path, the second dynamic optical path, and the third dynamic optical path, wherein the first dynamic optical path is the optical path between the curvature mirror and the first plane mirror, and the length of the first dynamic optical path is L. 1t , are variable; the second dynamic optical path is the optical path between the first and second plane mirrors, and the length of the second dynamic optical path is L. 2t , are variable; the third dynamic optical path is the optical path between the second plane mirror 322 and the focusing mirror, and the length of the third dynamic optical path is L. 3t , where L is a variable, generally L 3t ≤0.6m.

[0040] The main physical quantities in the dynamic optical path compensation system provided by this invention are:

[0041] 1. Initial beam diameter R1: The laser beam at the laser window mirror is called the initial beam, and the initial beam diameter R1 is stable;

[0042] 2. Original beam diameter R2: The laser beam that is directly transmitted to the incident surface of the focusing lens without being adjusted by the curvature mirror is called the original beam. The original beam diameter R2 will change with the total length L of the optical path.

[0043] 3. Target beam diameter R3: The laser beam transmitted to the incident surface of the focusing lens after being adjusted by the curvature mirror is called the target beam. The target beam diameter R3 is a system set value and is stable.

[0044] 4. Total optical path length L: The total length of the optical path between the window mirror and the focusing mirror. The total optical path length L is: L = L0 + L1 + L2 + L3, where the length of the fixed optical path L0 remains constant. The lengths of the first dynamic optical path L1, the second dynamic optical path L2, and the third dynamic optical path L3 change continuously during the operation of the 3D laser cutting machine with the changes in the position of the cantilever, Z-axis assembly, and laser cutting head, which is reflected as the real-time length L of the first dynamic optical path. 1t The real-time length L of the second dynamic optical path 2t The real-time length L of the third dynamic optical path 3t Therefore, the total optical path length L will also change continuously, which is reflected in the real-time total optical path length L. t For: L t =L0+L 1t +L 2t +L 3t ;

[0045] 5. Variable optical path S: The sum of the lengths L1 of the first dynamic optical path, L2 of the second dynamic optical path, and L3 of the third dynamic optical path is the variable optical path S; the variable optical path S at time t. t The real-time length L of the first dynamic optical path 1t The real-time length L of the second dynamic optical path 2t The real-time length L of the third dynamic optical path 3t The sum of S t =L 1t +L 2t +L 3t ; Variable optical path S at time t-1 t-1 The real-time length L of the first dynamic optical path 1(t-1) The real-time length L of the second dynamic optical path 2(t-1) The real-time length L of the third dynamic optical path 3(t-1) The sum of S t-1 =L 1(t-1) +L 2(t-1) +L 3(t-1) The maximum value of the variable optical path S is S0. max The minimum value is S min The maximum value of the variable optical path change ΔS is: ΔS max =S max -S min ;

[0046] 6. Target air pressure P 目 The required air pressure inside the curvature mirror, based on the variable optical path S.

[0047] 7. Real-time air pressure P 实 : Real-time air pressure inside the curvature mirror; the minimum working air pressure of the curvature mirror is P.min The maximum working air pressure is P max .

[0048] The following is an introduction to the selection strategy for curvature lenses:

[0049] 1) Calculate the range of the original beam diameter R2: based on the initial beam diameter R1, beam divergence angle α, and variable optical path S t Calculate the range of the original beam diameter R2;

[0050] 2) Determine the range of the target beam diameter R3: The range of the optimal aperture of the focusing lens is the range of the target beam diameter R3. The optimal aperture range of the focusing lens used in this invention is 25mm ± 0.5mm.

[0051] 3) Curvature Mirror Selection: The selected curvature mirror should be able to accommodate variable optical path lengths (S). t Take the maximum limit value S max and minimum limit value S min In each case, the original beam diameter R2 can be adjusted to the range of the target beam diameter R3, thereby determining the curvature mirror model.

[0052] The present invention has the following advantages over the prior art:

[0053] The dynamic optical path compensation control method of the present invention dynamically adjusts the original beam diameter in the three-dimensional laser cutting machine through a dynamic optical path control system. Even when the length of the laser optical path transmitted in the cutting machine changes dynamically, the target beam diameter and focal position transmitted to the laser cutting head can be kept stable. This achieves stable laser transmission in the dynamic three-dimensional processing system. The dynamic optical path compensation control method is precise and responsive, and can ensure uniform kerf width and smooth kerf edges while performing rapid laser cutting operations. Attached Figure Description

[0054] Appendix Figure 1 This is a control flowchart of the dynamic optical path compensation control method for the three-dimensional laser cutting machine of the present invention;

[0055] Appendix Figure 2 This is a test diagram of the far-end optical path of the three-dimensional laser cutting machine of the present invention;

[0056] Appendix Figure 3 This is a near-end optical path test diagram of the three-dimensional laser cutting machine of the present invention;

[0057] Appendix Figure 4 This is a front view of the Z-axis assembly of the three-dimensional laser cutting machine of the present invention.

[0058] Wherein: 1—laser; 11—light guide tube; 2—cutting machine tool; 21—machine tool body; 22—cantilever; 23—Z-axis assembly; 24—laser cutting head; 3—dynamic optical path control system; 31—curvature mirror; 311—first dynamic optical path; 312—second dynamic optical path; 313—third dynamic optical path; 321—first plane mirror; 322—second plane mirror. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0060] like Figure 1-3 As shown: A dynamic optical path compensation control method for a three-dimensional laser cutting machine. This control method can be used for dynamic optical path compensation control of a three-dimensional laser cutting machine, which consists of a laser 1, a cutting machine tool 2, and a dynamic optical path control system 3.

[0061] Laser 1 is used to generate a laser beam, which is guided by light guide tube 11 from one end of the cutting machine tool 2 into the machine tool body 21.

[0062] The dynamic optical path control system 3 includes a PLC controller, a curvature control unit, a curvature mirror 31, a first plane mirror 321, and a second plane mirror 322. The PLC controller communicates with the machine tool control center (CNC) to obtain real-time position information of the motion mechanism on the 3D laser cutting machine from the CNC, and is used to calculate the variable optical path S. t The motion mechanism includes a cantilever 22, a Z-axis assembly 23, and a laser cutting head 24; the curvature control unit includes a numerically controlled proportional valve, an air supply mechanism, and a pressure sensor. The air supply mechanism precisely supplies air to the curvature mirror 31 via the numerically controlled proportional valve, and adjusts the curvature of the curvature mirror 31 by adjusting the air pressure; the pressure sensor is used to collect the real-time air pressure P in the curvature mirror 31. 实 The data is fed back to the PLC controller to monitor the air pressure in the curvature mirror 31 in real time.

[0063] The cutting machine tool 2 includes a machine body 21, a cantilever 22, and a Z-axis assembly 23. A laser cutting head 24 is located at the end of the Z-axis assembly 23. An optical path system is constructed by arranging multiple optical lenses within the cutting machine tool 2. The laser beam is sequentially transmitted through the machine body 21 and the cantilever 22 to the laser cutting head 24 at the end of the Z-axis assembly 23. Finally, the laser cutting head 24 outputs the laser beam to cut the workpiece. This optical path system is controlled by a dynamic optical path control system 3. Within this optical path system, the optical path can be divided into at least four segments, using the optical lenses as dividing points:

[0064] Fixed optical path: The laser beam generated by laser 1 is output from the window mirror and then guided into the machine tool body 21 by the light guide tube 11. After being transmitted through the optical path, it is incident on the curvature mirror 31. The curvature mirror 31 is fixedly connected to the machine tool body 21. The section of the optical path between the window mirror and the curvature mirror 31 is the fixed optical path. A plane mirror can be added before the beam is incident on the curvature mirror 31 to change the direction of the optical path, but the length L0 of the fixed optical path remains unchanged. Generally, 0 < L0 ≤ 1m.

[0065] First dynamic optical path 311: After being reflected by the curvature mirror 31, the laser is transmitted along the length of the machine tool body 21 and incident on the first plane mirror 321 at one end of the cantilever 22. The cantilever 22 will drive the first plane mirror 321 to move back and forth on the machine tool body 21 along the Y-axis. The position of the first plane mirror 321 will change continuously, and the length of the optical path between the curvature mirror 31 and the first plane mirror 321 will also change continuously. This optical path is the first dynamic optical path 311, and the optical path length is L1, where L1 is a variable.

[0066] Second dynamic optical path 312: After being reflected by the first plane mirror 321, the laser is transmitted along the length of the cantilever 22 and incident on the second plane mirror 322 on the Z-axis assembly 23. The Z-axis assembly 23 will drive the second plane mirror 322 to move back and forth along the X-axis on the cantilever 22. The position of the second plane mirror 322 will change continuously, and the length of the optical path between the first plane mirror 321 and the second plane mirror 322 will also change continuously. This optical path is the second dynamic optical path 312, and the length of the optical path is L2, which is a variable.

[0067] The third dynamic optical path 313: After being reflected by the second plane mirror 322, the laser is transmitted downward along the length of the Z-axis assembly 23 and incident on the focusing lens in the laser cutting head 24. The Z-axis assembly 23 drives the laser cutting head 24 to move back and forth along the Z-axis. The position of the focusing lens will change continuously, and the length of the optical path between the second plane mirror 322 and the focusing lens will also change continuously. This optical path is the third dynamic optical path 313, and the length of the optical path is L3. L3 is a variable, and generally L3≤0.6m.

[0068] In the three-dimensional laser cutting machine provided by this invention, the laser is output from the window mirror of the laser 1. The laser beam at the window mirror of the laser 1 is called the initial beam, and the initial beam diameter R1 is stable. The laser is reflected sequentially by the curvature mirror 31, the first plane mirror 321, and the second plane mirror 322 before entering the focusing mirror in the laser cutting head 24. The original beam diameter at the incident surface of the focusing mirror is R2. The total optical path length L between the window mirror and the focusing mirror is: L = L0 + L1 + L2 + L3, where the length L0 of the fixed optical path is fixed and constant, while the lengths L1 of the first dynamic optical path 311, L2 of the second dynamic optical path 312, and L3 of the third dynamic optical path 313 change continuously during the operation of the three-dimensional laser cutting machine, which is reflected as the real-time length L of the first dynamic optical path 311. 1t The real-time length L of the second dynamic optical path 312 2t The real-time length L of the third dynamic optical path 313 3t Therefore, the total optical path length L will also change continuously, which is reflected in the real-time total optical path length L. t For: L t =L0+L 1t +L 2t +L 3t Because laser transmission has a divergence angle, the beam diameter gradually increases during transmission. Therefore, R2 > R1, and the total real-time optical path length L... t As the beam size increases, the original beam diameter R2 also increases, and the total real-time optical path length L... t As the diameter of the original beam decreases, the diameter of the original beam R2 also decreases. Therefore, the diameter of the original beam R2 at the incident surface of the focusing lens will continuously change during the operation of the 3D laser cutting machine. This change in the original beam diameter R2 negatively impacts the laser cutting quality. Because a laser beam with an original diameter of R2, after being focused by the focusing lens, will form a target beam with a diameter of R3 and a focal length of f to perform laser cutting on the workpiece, the diameters of the target beam R3 and the focal length f will also change with the change in the original beam diameter R2. Changes in the target beam diameter R3 will lead to uneven kerf width, and changes in the focal length f will lead to instability in the focal position of the focused beam. Consequently, the laser beam cannot be accurately focused on the cutting surface of the workpiece. This instability in the focal position not only leads to uneven kerf but also to quality problems such as rough kerf edges. Therefore, to obtain stable laser cutting quality, it is necessary to maintain the stability of the target beam diameter R3 and the focal length f as much as possible. The stability of the target beam diameter R3 and the focal length f depends on the stability of the original beam diameter R2. The change in the original beam diameter R2 is due to the change in the total real-time optical path length L in the dynamic optical path. t The constant changes in the total length L of the optical path in a 3D laser cutting machine, caused by the operation of the motion mechanism, result in a real-time variation. t Changes are also unavoidable. To ensure the total real-time optical path length L... tThe present invention achieves the technical effect of stabilizing the original beam diameter R2 under changing conditions. The dynamic optical path compensation control method provides dynamically adjusts the beam diameter after reflection by the curvature mirror 31 by adjusting the curvature of the curvature mirror 31, so that the beam diameter changes with the real-time total optical path length L. t The change is based on the principle that the diameter R2 of the original laser beam transmitted to the incident surface of the focusing lens should remain stable within the error range.

[0069] Based on the aforementioned three-dimensional laser cutting machine, this invention provides two dynamic optical path compensation control methods: the first is a continuous dynamic optical path compensation control method, and the second is a segmented dynamic optical path compensation control method, which are described below.

[0070] A dynamic optical path compensation control method for a three-dimensional laser cutting machine is disclosed. This method is a continuous dynamic optical path compensation control method, and the specific steps are as follows:

[0071] A. The PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool 2 and calculates the variable optical path S at time t. t And obtain the variable optical path change ΔS=S when the time interval is ΔT. t -S t-1 When ΔS≠0, proceed to step B;

[0072] B. The PLC controller determines the target air pressure P in the curvature mirror 31 based on the variable optical path change ΔS. 目 P 目 =P 实 +ΔP, and the value of the pressure change ΔP is a negative number equal to half the value of the variable optical path change ΔS. 实 This refers to the real-time air pressure in the current curvature mirror 31;

[0073] C. The PLC controller outputs an air pressure regulation command to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror 31 in the reverse direction to the target air pressure P. 目 This enables dynamic adjustment of the curvature of the curvature mirror 31, thereby maintaining the diameter of the beam reaching the focusing mirror as the target beam diameter R3, with an error range of ±0.1mm for the target beam diameter R3.

[0074] A dynamic optical path compensation control method for a three-dimensional laser cutting machine is disclosed. This method is a segmented dynamic optical path compensation control method, and the specific steps are as follows:

[0075] A. The PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool 2 and calculates the variable optical path S at time t. t And obtain the variable optical path change ΔS=S t -S min When ΔS≠0, proceed to step B;

[0076] B. The PLC controller directly determines the target air pressure P based on the optical path range in which the variable optical path change ΔS falls. 目 ;

[0077] C. The PLC controller compares the real-time air pressure P in the curvature mirror 31. 实 and target air pressure P 目 When P 实 =P 目 When P returns to step A, 实 ≠P 目 At that time, proceed to step D;

[0078] D. The PLC controller outputs an air pressure regulation command to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror 31 in the reverse direction to the target air pressure P. 目 This allows for dynamic adjustment of the curvature of the curvature mirror 31, thereby maintaining the beam diameter reaching the focusing lens at the target beam diameter R3, with an error range of ±0.5mm.

[0079] In the segmented dynamic optical path compensation control method, the target air pressure P in step B... 目 The method for determining it is as follows:

[0080] B1. The maximum value ΔS of the variable optical path change. max Divide into n equal parts, according to ΔS max The pattern is divided into (n+1) optical path ranges;

[0081] B2. Determine the maximum value ΔS of the variable optical path change. max Minimum target air pressure P at that time min目 The value of the target air pressure, or the maximum value P when the variable optical path change ΔS = 0. max目 The value;

[0082] B3. According to the rule that the optical path range corresponding to the variable optical path change ΔS increases from small to large, the target air pressure P corresponding to each optical path range... 目 The value is determined by the maximum target air pressure P. max目 The values ​​are according to The value decreases; or according to the law that the optical path range corresponding to the variable optical path change ΔS decreases from large to small, the target air pressure P corresponding to each optical path range. 目 The value is determined by the minimum target air pressure P. min目 The values ​​are according to The value increases.

[0083] In the dynamic optical path compensation control method for the three-dimensional laser cutting machine provided by the present invention, the PLC controller collects the real-time air pressure P in the curvature mirror 31 in real time through a pressure sensor. 实 The PLC controller will monitor the real-time air pressure P 实 The numerical value and target air pressure P 目 The values ​​of P are compared multiple times. 实 >P 目 , or P 实 <P 目 If the abnormal state persists for more than the set time, the PLC controller will report the abnormal information to the machine tool control center, which will then issue an alarm and suspend the cutting operation of cutting machine 2. Similarly, the PLC controller will collect the real-time air pressure P in the curvature mirror 31 via a pressure sensor. 实 and the maximum air pressure P in the curvature mirror 31 max and minimum air pressure P min Compare, when P 实 >P max Time, or P 实 <P min When this happens, the PLC controller will send the abnormal information to the machine tool control center, which will then issue an alarm and suspend the cutting operation of cutting machine 2.

[0084] The following example uses a segmented dynamic optical path compensation control method to illustrate the method for compiling dynamic adjustment instructions for the curvature mirror 31 in the dynamic optical path compensation control method of the three-dimensional laser cutting machine provided by this invention.

[0085] (I) Near-end and far-end optical path testing

[0086] Remote testing: Adjust both the cantilever 22 and Z-axis assembly 23 of the 3D laser cutting machine to their extreme positions far from the curvature mirror 31. At this point, the cantilever 22 is at its extreme position on the machine body 21, away from the curvature mirror 31, and the Z-axis assembly 23 is at its extreme position on the cantilever 22, away from the machine body 21. At this point, the variable optical path S is at its maximum value. max When the beam travels the farthest, the original beam diameter R2 at the focusing lens also reaches its maximum value. Adjusting the air pressure of the curvature mirror 31 transforms it into a concave mirror to converge the laser beam, thus adjusting the original beam diameter R2 at the focusing lens to the target beam diameter R3. Record the far-end air pressure value P at this point. 远 And the target beam diameter R3.

[0087] Near-end test: Adjust both the cantilever 22 and Z-axis assembly 23 of the 3D laser cutting machine to their extreme positions close to the curvature mirror 31. At this point, the cantilever 22 is at its extreme position on the machine body 21 near the curvature mirror 31, and the Z-axis assembly 23 is at its extreme position on the cantilever 22 near the machine body 21. At this point, the variable optical path S is at its minimum value S. min When the beam transmission distance is shortest, the original beam diameter R2 at the focusing lens also reaches its minimum value. Adjusting the air pressure of the curvature mirror 31 transforms it into a convex mirror that diverges the laser beam, thus adjusting the original beam diameter R2 at the focusing lens to the target beam diameter R3. Record the near-end air pressure value P at this time. 近 And the target beam diameter R3.

[0088] (II) Calculation of corresponding parameters for optical path and air pressure

[0089] The maximum value of the variable optical path change ΔS max Taking a 6m three-dimensional laser cutting machine as an example, a parameter table corresponding to the optical path and air pressure during the adjustment process of the curvature mirror 31 is compiled, such as the P obtained in the near-far end test. 远 =1.5Pa, P 近 =4.5Pa. The following table is compiled based on the linear relationship between the variable optical path change and the target air pressure in the curvature mirror 31.

[0090] Table 1. Linear Relationship between Variable Optical Path Change and Target Air Pressure in Curvature Mirror 31

[0091] Variable optical path change ΔS(m) [0,1) [1,2) [2,3) [3,4) [4,5) [5,6) 6 <![CDATA[Target air pressure P 目 (Pa)]]> 4.5 4.0 3.5 3.0 2.5 2.0 1.5

[0092] (III) Developing the air pressure regulation program for the curvature mirror 31

[0093] According to the air pressure adjustment instructions for the curvature mirror 31 compiled in Table 1, during the operation of the 3D laser cutting machine, in order to achieve 3D cutting of the workpiece, the positions of the cantilever 22, Z-axis assembly 23, and laser cutting head 24 on the cutting machine tool 2 will continuously change according to the cutting trajectory requirements. The variable optical path change ΔS during the change process varies within the range of 0m≤ΔS≤6m. The target air pressure P in the curvature mirror 31... 目 The curvature mirror 31 is adjusted according to the following instructions, which vary with the variable optical path ΔS, thereby keeping the diameter of the beam reaching the focusing mirror as the target beam diameter R3 with an error range of ±0.5mm.

[0094] The main contents of the air pressure adjustment program of the curvature mirror 31 are as follows:

[0095] When 0m≤ΔS<1m, the curvature control unit will control the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =4.5Pa;

[0096] When 1m ≤ ΔS < 2m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =4.0Pa;

[0097] When 2m ≤ ΔS < 3m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =3.5Pa;

[0098] When 3m ≤ ΔS < 4m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =3.0Pa;

[0099] When 4m ≤ ΔS < 5m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =2.5Pa;

[0100] When 5m ≤ ΔS < 6m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =2.0Pa;

[0101] When ΔS = 6m, the curvature control unit will adjust the target air pressure P in the curvature mirror 31. 目 Adjust to P 目 =1.5Pa.

[0102] (iv) Input the above air pressure regulation program into the PLC controller, and directly call the air pressure regulation program when generating air pressure regulation instructions.

[0103] The following example, using the three-dimensional laser cutting machine provided by this invention with the above-mentioned air pressure regulation program, will further illustrate the phased dynamic optical path compensation control method.

[0104] 1. Issuing machine tool operation commands: The CNC machine tool control center issues operation commands to the motion mechanisms such as the cantilever 22, Z-axis assembly 23, and laser cutting head 24 on the cutting machine tool 2 according to the laser cutting trajectory code;

[0105] 2. Feedback command completion: The motion mechanism on the cutting machine tool 2 runs according to the running command, and after the operation is completed, it feeds back the command completion information to the machine tool control center CNC;

[0106] 3. Transmitting position information to PLC: The CNC machine tool control center transmits the position information of the motion mechanism on the cutting machine tool 2 to the PLC controller;

[0107] 4. Generate air pressure regulation command: The PLC controller calculates the variable optical path S at time t based on the real-time position information of the cantilever 22, Z-axis assembly 23, and laser cutting head 24. t It calls the air pressure regulation program to generate air pressure regulation commands;

[0108] For example:

[0109] 1) At time t, the PLC controller calculates the variable optical path S at time t based on the real-time position information of the moving mechanism. t And obtained the variable optical path change ΔS = 3.5m;

[0110] 2) The PLC controller calls the air pressure regulation program to generate an air pressure regulation instruction: adjust the target air pressure in the curvature mirror 31 to P. 目 =3.0Pa;

[0111] 3) The PLC controller compares the existing air pressure P in the curvature mirror 31. 现 (i.e., the real-time air pressure P at time t) 实 ) and the target air pressure P required in the instruction 目 ;

[0112] (1) When P 实 =P 目 At this time, the existing air pressure in the curvature mirror 31 does not need to be adjusted, and the PLC controller does not issue an air pressure adjustment command.

[0113] (2) When P 实 ≠P 目 At this time, the existing air pressure in the curvature mirror 31 needs to be adjusted to the target air pressure P. 目 The PLC controller sends an air pressure regulation command to the curvature control unit;

[0114] 5. Execute the air pressure adjustment command: The air supply mechanism in the curvature control unit precisely supplies air to the curvature mirror 31 through a numerically controlled proportional valve, adjusting the air pressure in the curvature mirror 31 to the target air pressure P. 目 .

[0115] 6. Real-time air pressure monitoring: After the air pressure adjustment command is executed, the pressure sensor collects the real-time air pressure P in the curvature mirror 31. 实 The data is then fed back to the PLC controller, which compares it with the real-time air pressure P. 实 The numerical value and target air pressure P 目 The value;

[0116] 1) When P 实 =P 目 When the air pressure regulation command is completed, steps 1-6 are executed in a loop.

[0117] 2) When P 实<P 目 At this time, the PLC controller will issue a command to compensate for the gas output, and at the same time, the PLC controller will scan the real-time gas pressure P. 实 The numerical value and target air pressure P 目 The values ​​of P are compared multiple times. 实 <P 目 If the abnormal status persists for more than 1000ms, the PLC controller will send the abnormal information to the machine tool control center (CNC). The CNC will then issue an alarm, and the cutting machine 2 will suspend its cutting operation.

[0118] 3) When P 实 >P 目 At this time, the PLC controller will issue a command to reduce gas output, and at the same time, the PLC controller will scan the real-time gas pressure P. 实 The numerical value and target air pressure P 目 The values ​​of P are compared multiple times. 实 >P 目 If the abnormal status persists for more than 1000ms, the PLC controller will send the abnormal information to the machine tool control center (CNC). The CNC will then issue an alarm and the machine will suspend the cutting operation.

[0119] 7. Air pressure over-limit alarm

[0120] The minimum working air pressure of the curvature mirror 31 is P min The maximum working air pressure is P max Real-time air pressure P collected by pressure sensor 实 ;

[0121] 1) When P 实 <P min When this happens, the PLC controller will send the abnormal information to the machine tool control center (CNC), which will then issue an alarm and suspend the cutting operation.

[0122] 2) When P 实 >P max When this happens, the PLC controller will send the abnormal information to the machine tool control center (CNC), which will then issue an alarm and suspend the cutting operation.

[0123] 8. Alarm Handling: After an alarm is triggered, the machine tool will pause the cutting operation. The operator needs to investigate the cause of the alarm and remove the relevant obstacles to clear the alarm. Common causes of alarms include insufficient gas pressure and CNC proportional valve failure. After the problem is resolved, the operator presses the "Start" button on the OP cabinet, and the cutting machine tool 2 will restart and resume the cutting operation from the paused position.

[0124] The dynamic optical path compensation control method of the present invention dynamically adjusts the original beam diameter R2 in the three-dimensional laser cutting machine through the dynamic optical path control system 3. Even when the length of the laser optical path transmitted in the cutting machine tool 22 changes dynamically, it can still ensure that the target beam diameter R2 and the position of the focal point transmitted to the laser cutting head 24 are stable. It realizes stable laser transmission in the dynamic three-dimensional processing system. The dynamic optical path control system 3 has precise control and rapid response. It can also ensure uniform kerf width and smooth kerf edge while performing rapid laser cutting operations.

[0125] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention. Technologies not covered in this invention can be implemented using existing technologies.

Claims

1. A dynamic optical path compensation control method of a three-dimensional laser cutting machine, characterized in that: The steps of this method are as follows: A, PLC controller acquires real-time position information of the motion mechanism in the cutting machine tool, calculates variable optical path at the moment , and obtains variable optical path change amount at the time interval , when , enters step B; B. The PLC controller is based on the variable optical path change. Determine the target air pressure in the curvature mirror , And the change in air pressure The value represents the variable optical path change. A negative number that is half the value of the number. This represents the real-time air pressure within the current curvature mirror. C. The PLC controller outputs air pressure regulation commands to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror to the target air pressure. This allows for dynamic adjustment of the curvature of the curvature mirror, thereby maintaining the diameter of the beam reaching the focusing lens at the target beam diameter. .

2. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to claim 1, characterized in that: The time interval at which the PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool in step A. The time is 10ms; the target beam diameter in step C is... The error range is ±0.1mm.

3. A dynamic optical path compensation control method for a three-dimensional laser cutting machine, characterized in that: The steps of this method are as follows: A. The PLC controller acquires the real-time position information of the motion mechanism in the cutting machine tool and calculates... Variable optical path at time And obtain the variable optical path change. ,when Proceed to step B; B. The PLC controller is based on the variable optical path change. The optical path range directly determines the target air pressure. ; C. The PLC controller compares the real-time air pressure in the curvature mirror. and target air pressure ,when When, return to step A, when At that time, proceed to step D; D. The PLC controller outputs an air pressure regulation command to the curvature control unit, which precisely supplies air to adjust the air pressure in the curvature mirror in the opposite direction to the target air pressure. This allows for dynamic adjustment of the curvature of the curvature mirror, thereby maintaining the diameter of the beam reaching the focusing lens at the target beam diameter. ; The target air pressure in step B The method for determining it is as follows: B1. The maximum value of the variable optical path change. conduct Divide equally, according to , , , The patterns are divided into One optical path range; B2. Determine the maximum value of the variable optical path change. Minimum target air pressure at that time The value, or the variable optical path change The target air pressure maximum value at that time The value; B3. According to the variable optical path change The corresponding optical path range follows a pattern of increasing from small to large, and the target air pressure corresponds to each optical path range. The value is determined by the maximum target air pressure. The value according to The value decreases; or according to the variable optical path change. The corresponding optical path range decreases from large to small, and the target air pressure corresponds to each optical path range. The value is determined by the minimum target air pressure. The values ​​are according to The value increases.

4. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to claim 3, characterized in that: In step C, the time interval for the PLC controller to acquire the real-time position information of the motion mechanism in the cutting machine tool is 1000ms; the target beam diameter in step C... The error range is ±0.5mm.

5. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to any one of claims 1-4, characterized in that: The PLC controller uses a pressure sensor to collect real-time air pressure data in the curvature mirror. The PLC controller will monitor the real-time air pressure. The numerical value and target air pressure The values ​​are compared multiple times, if If the state persists for more than the set time, the PLC controller will... If the abnormal status lasts for more than the set time, the abnormal information is fed back to the machine tool control center, which will issue an alarm and suspend the cutting operation of the cutting machine.

6. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to any one of claims 1-4, characterized in that: The PLC controller uses a pressure sensor to collect real-time air pressure data in the curvature mirror. The PLC controller will monitor the real-time air pressure. The numerical value and target air pressure The values ​​are compared multiple times, if If the state persists for more than the set time, the PLC controller will... If the abnormal status lasts for more than the set time, the abnormal information is fed back to the machine tool control center, which will issue an alarm and suspend the cutting operation of the cutting machine.

7. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to any one of claims 1-4, characterized in that: The PLC controller uses a pressure sensor to collect real-time air pressure data in the curvature mirror. ,when time, or At that time, the PLC controller will ,or The abnormal information is fed back to the machine tool control center, which then issues an alarm and suspends the cutting operation of the cutting machine.

8. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to any one of claims 1-4, characterized in that: The curvature control unit includes an air supply mechanism, a numerically controlled proportional valve, and a pressure sensor. The air supply mechanism supplies air to the curvature mirror through the numerically controlled proportional valve. The numerically controlled proportional valve is connected to a PLC controller via a circuit to receive and execute air pressure regulation commands issued by the PLC controller. The pressure sensor is connected to the PLC controller via a circuit to collect real-time air pressure data in the curvature mirror. And then feed back to the PLC controller.

9. The dynamic optical path compensation control method for a three-dimensional laser cutting machine according to any one of claims 1-4, characterized in that: The variable optical path The sum of the first dynamic optical path, the second dynamic optical path, and the third dynamic optical path, wherein the first dynamic optical path is the optical path between the curvature mirror and the first plane mirror, and the length of the first dynamic optical path is... , are variable; the second dynamic optical path is the optical path between the first and second plane mirrors, and the length of the second dynamic optical path is . , are variable; the third dynamic optical path is the optical path between the second plane mirror (322) and the focusing mirror, and the length of the third dynamic optical path is . , are variable. .

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