Combined laser cutting machining head with replaceable cutting nozzle

Abstract

The present application belongs to the technical field of metal hot cutting, and discloses a combined laser cutting machining head with replaceable cutting nozzle, which comprises a laser cutting head main body, a laser beam focusing unit, an optical system unit, a connecting unit and a cutting nozzle unit. The laser beam focusing unit is installed on the laser cutting head main body, and the other three units are sequentially arranged from top to bottom. The optical system unit is arranged in the laser cutting head main body. The connecting unit is connected with the lower end of the laser cutting head main body and located directly below the optical system unit. The cutting nozzle unit is detachably installed at the lower end of the connecting unit. The present application not only breaks through the limitations of high equipment cost and low cutting efficiency of traditional laser cutting process in the field of medium-thickness and large-thickness metal material cutting, but also overcomes the technical bottleneck of poor quality of flame-assisted laser cutting process in thin metal material cutting. The present application can meet the demand of high-quality cutting of metal materials with different thicknesses without the need for very high power laser output.

Description

Technical Field

[0001] This invention belongs to the field of metal thermal cutting technology, and more specifically, relates to a combined laser cutting head with replaceable cutting nozzles. Background Technology

[0002] Laser cutting technology, as an emerging metal thermal cutting technology, has been widely applied in fields such as machinery manufacturing, automotive, and aerospace due to its unique principles. In the cutting of thin sheet metal materials, laser cutting technology, with its high-energy-density laser beam as a heat source, can cut thin sheet metal materials at extremely high speeds, with good cutting quality, narrow kerf width, high cutting precision, and a small heat-affected zone. Therefore, it holds an absolute advantage in cutting thin sheet metal materials and even medium-thickness metal materials (around 20mm). However, when the metal material thickness exceeds 30mm, not only are the laser power requirements for laser cutting very high, but the laser cutting efficiency and quality also decrease sharply, leading to a significant increase in the cost of cutting equipment. In particular, simply increasing the laser power has a very limited effect on improving the cutting speed of thick metal materials. In conclusion, laser cutting technology no longer holds an advantage over traditional cutting technologies such as flame cutting and plasma cutting in the cutting of thick metal materials.

[0003] On the other hand, traditional flame cutting technology, with its advantages of excellent cutting capability for thick metal plates and low equipment cost, has always been one of the main methods for cutting thick metal materials. However, flame cutting technology also has many shortcomings, such as the need for long preheating before cutting, low cutting efficiency, and difficulty in piercing, which limits its application in many cases, often forcing the cutting of thick plates to rely on machining techniques such as milling. Therefore, flame-assisted laser cutting technology has been proposed in this field to combine the advantages of high precision, high speed, and good cutting quality of laser cutting with the strong ability of flame to cut thick metal materials. By using a high-temperature flame to preheat the workpiece, the laser power required for laser cutting can be significantly reduced, thus requiring only a lower-power laser to cut thicker workpieces, and therefore has significant industrial application value.

[0004] While flame-assisted laser cutting offers significantly higher cutting efficiency and kerf quality than traditional laser or flame cutting techniques for thick metal materials, the introduction of a combustion flame results in a wider kerf and a larger heat-affected zone, limiting its effectiveness to thick plates. Using the same method to cut thin metal materials yields less desirable results. In other words, while flame-assisted laser cutting heads can cut thick metal materials, they offer no advantage in terms of cutting speed or kerf quality when cutting thin metal materials. Traditional laser cutting heads, on the other hand, can cut thin metal materials with high quality and efficiency, but face significant limitations when cutting thick metal materials. Therefore, if the advantages of traditional laser cutting technology in cutting thin metal materials and the advantages of flame-assisted laser cutting technology in cutting thick metal materials can be combined, so that a single laser cutting machine and a single laser cutting head can efficiently and effectively cut both thick and thin metal materials, it will undoubtedly greatly improve the process adaptability and equipment utilization of laser cutting equipment. This has significant engineering application value for the industrial field. The key is to develop a "universal" laser cutting head that can achieve high-efficiency and high-quality cutting of both thick and thin metal materials. Summary of the Invention

[0005] In response to the various shortcomings or improvement needs of existing laser cutting technology, this invention provides a modular laser cutting head with replaceable cutting nozzles. It can meet the demand for high-quality cutting of metal materials of different thicknesses, and overcome the limitations of traditional laser cutting processes in the field of cutting thick metal materials, such as high equipment cost and low cutting efficiency, as well as the technical bottlenecks of flame-assisted laser cutting processes in cutting thin sheet metal materials, such as poor quality and low processing efficiency.

[0006] To achieve the above objectives, this invention proposes a modular laser cutting head with replaceable cutting nozzles. It includes a laser cutting head body, a laser beam focusing unit, an optical system unit, a connecting unit, and a cutting nozzle unit. The laser beam focusing unit is mounted on the laser cutting head body and is used to adjust the focal point position of the laser beam emitted from the optical system unit. The optical system unit, connecting unit, and cutting nozzle unit are arranged sequentially from top to bottom. The optical system unit is located within the laser cutting head body and is replaceable. It is used to transform the externally input laser beam and guide it to the connecting unit. The connecting unit is connected to the lower end of the laser cutting head body and is located directly below the optical system unit. It guides the laser beam to the cutting nozzle unit. The cutting nozzle unit is detachably mounted on the lower end of the connecting unit and guides the laser beam and cutting gas to the workpiece to be cut, thereby achieving the cutting of the workpiece.

[0007] As a further preferred embodiment, the cutting nozzle unit includes a mounting base, a cutting nozzle, and a height sensing component. The mounting base has a cutting gas channel, and the cutting nozzle is detachably mounted on the mounting base. It has a laser channel that is connected to the cutting gas channel on the mounting base.

[0008] As a further preferred embodiment, the height sensing component is a capacitive height adjustment component, an arc voltage height adjustment component, or a mechanical height adjustment component.

[0009] As a further preferred embodiment, the height sensing component is preferably a capacitive height adjustment component, comprising a ceramic ring, a sensing nozzle, a spring probe, and a connector. The ceramic ring is detachably mounted on the bottom of the mounting base and surrounds the cutting nozzle. The sensing nozzle is mounted on the bottom of the ceramic ring and surrounds the cutting nozzle. The connector is mounted on the mounting base and is electrically connected to the spring probe and an external controller. The spring probe is connected to the upper end of the ceramic ring, and the lower end of the ceramic ring contacts the sensing nozzle. The spring probe is also electrically connected to the sensing nozzle.

[0010] As a further preferred embodiment, the mounting base is also provided with a combustion gas channel and a combustion-supporting gas channel, wherein the combustion gas channel is used to deliver combustion gas to the cutting nozzle, and the combustion-supporting gas channel is used to deliver combustion-supporting gas to the cutting nozzle.

[0011] As a further preferred embodiment, the cutting nozzle is a flame-assisted laser cutting nozzle or a laser cutting nozzle. The flame-assisted laser cutting nozzle includes a nozzle body, with a laser channel in the middle and a mixed gas channel on the side. The laser channel is for the passage of the laser beam and cutting gas, and the mixed gas channel is for the passage of combustion gas and combustion-supporting gas. The lower end of the laser channel is designed with a Laval structure. The laser cutting nozzle includes a laser cutting nozzle body, with a laser channel in the middle for the passage of the laser beam and cutting gas; or the laser cutting nozzle body has a laser channel in the middle and a cutting gas channel on the side, wherein the laser channel is for the passage of the laser beam and the cutting gas channel is for the passage of the cutting gas.

[0012] As a further preferred embodiment, the flame-assisted laser cutting nozzle also includes a gas mixing unit, which is connected to the combustion gas channel and / or combustion-supporting gas channel on the mounting base.

[0013] As a further preferred embodiment, the gas mixing unit includes a gas mixing structure and an air intake structure connected to each other. The air intake structure is used to send combustion gas and combustion-supporting gas into the gas mixing structure through different inlets. The gas mixing structure is used to mix the combustion gas and combustion-supporting gas and then send them into the mixed gas channel through the combustion gas channel and / or combustion-supporting gas channel on the mounting base.

[0014] As a further preferred embodiment, the air intake structure is an injection-type structure, which includes two inlets, one for inputting combustion-supporting gas and the other for inputting combustion gas.

[0015] As a further preferred embodiment, the optical system unit includes a collimating lens assembly and a focusing lens assembly arranged vertically, with protective lens assemblies provided above the collimating lens assembly and below the focusing lens assembly.

[0016] As a further preferred embodiment, the laser cutting head body has multiple horizontal mounting slots from top to bottom, and the collimating lens assembly, focusing lens assembly, and protective lens assembly are integrally arranged in the corresponding horizontal mounting slots in an insert manner.

[0017] As a further preferred embodiment, the collimating lens assembly includes a collimating lens mount and a collimating lens. The collimating lens mount has a lens mounting slot, and the collimating lens is installed in the lens mounting slot of the collimating lens mount for collimating the laser beam. The collimating lens mount is also connected to a lens mount connector, and the collimating lens mount is connected to the laser beam focusing unit through the lens mount connector.

[0018] As a further preferred embodiment, the focusing lens assembly includes a focusing lens, a focusing lens mount, a mount connecting plate, and an elastic mounting member. The focusing lens is fixed within the focusing lens mount. A mounting groove is circumferentially formed on the outer side of the focusing lens mount. The elastic mounting member is arranged circumferentially around the outer side of the focusing lens mount and is embedded in the mounting groove. Both ends of the elastic mounting member are fixed to the mount connecting plate. A positioning plate is provided on the side of the focusing lens mount facing the mount connecting plate. The mount connecting plate is detachably connected to the laser cutting head body and has a positioning groove that mates with the positioning plate. An adjusting rod is also installed on the mount connecting plate, with one end of the adjusting rod abutting against the outer surface of the focusing lens mount. The relative position of the focusing lens mount and the mount connecting plate is adjusted by the movement of the adjusting rod.

[0019] As a further preferred embodiment, the focusing lens is a multifocal focusing lens. Preferably, the multifocal focusing lens is a single lens, a combination lens, a diffractive lens, a reflective lens, or a metal lens. Preferably, the multifocal focusing lens is a single plano-convex lens, with one side being a plane and the other side being a convex curved surface. The convex curved surface is composed of multiple focal curved surfaces with different curvatures, and the curvature of each focal curved surface gradually increases from the center of the multifocal focusing lens outwards. Adjacent focal curved surfaces are transitioned by transition surfaces.

[0020] As a further preferred embodiment, the protective mirror assembly includes a protective mirror base and a protective mirror. The protective mirror is mounted on the protective mirror base via a fixing assembly. The protective mirror base is connected to a protective mirror connecting plate, and the protective mirror connecting plate is detachably connected to the laser cutting head body.

[0021] As a further preferred embodiment, the laser beam focusing unit includes a motor, a lead screw, a guide rail, and a guide rail slider. The motor is mounted on the laser cutting head body and connected to the lead screw to drive the lead screw to rotate. The lead screw is threadedly engaged with the lens mount connecting body. The guide rail is mounted on the laser cutting head body and slidably engaged with the guide rail slider. The guide rail slider is connected to the lens mount connecting body through a guide rail connecting plate.

[0022] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0023] 1. The interchangeable-nozzle combined laser cutting head provided by this invention allows for the replacement of the cutting nozzle unit according to the thickness of the workpiece. When cutting thin sheet metal materials, a traditional laser cutting mode is used; when cutting thick sheet metal materials, a flame-assisted laser cutting mode is used, thus achieving the goal of one cutting head capable of cutting metal materials of all thicknesses, without requiring a very high laser power. This invention allows for switching between different cutting modes when cutting metal materials of different thicknesses by replacing the cutting nozzle unit at the bottom of the cutting head or replacing the cutting nozzle within the cutting nozzle unit. It features simple operation and strong practicality, effectively combining and fully utilizing the advantages of traditional laser cutting of thin sheet metal materials (high cutting speed, good cutting quality, small kerf width, and small heat-affected zone) with the advantages of flame-assisted laser cutting of thick sheet metal materials (large cutting thickness, high efficiency, low equipment cost, and good cutting quality), to achieve low-cost, high-efficiency cutting of metal materials of all thicknesses.

[0024] 2. The combined laser cutting head provided by this invention has dynamic focusing and height sensing functions. On the one hand, through the structural design of the laser beam focusing unit, the laser beam focus can be intelligently adjusted to adapt to different piercing and cutting processes. On the other hand, through the structural design of the cutting nozzle unit, the distance between the nozzle and the surface of the workpiece to be cut can be monitored in real time. Then, during cutting, the height of the entire cutting head can be adjusted by an external controller according to the height sensing signal, so that the focus of the laser beam is always located at the same position on the workpiece to be cut during the cutting process, thereby ensuring the stability and reliability of the cutting quality.

[0025] 3. When the cutting head of the present invention is used to cut thick metal materials in flame-assisted laser cutting mode, the focal depth of the laser beam can be increased by changing the focusing lens of the cutting head, so that the focal point of the laser beam is located below the surface of the workpiece to be cut. At the same time, since the lower end of the flame-assisted laser cutting nozzle is a Laval structure, the cutting oxygen can be accelerated to a supersonic flow rate, thereby ensuring that the oxygen concentration and flow rate at the bottom of the kerf are maintained at a high level, so that the oxygen-iron reaction is more complete, more heat energy is released, and the slag is blown off better, thus obtaining better kerf quality and processing efficiency.

[0026] 4. The cutting head provided by this invention has a flame-assisted laser cutting function. When paired with a supersonic Laval structure cutting nozzle, it can cut metal materials of full thickness (1mm-200mm) using a low-power laser (1kW-8kW). This effectively avoids the problems of high-power lasers (10kW, 20kW or even higher) and low cutting efficiency required when cutting thick metal materials (thickness greater than 30mm) using traditional laser cutting processes. While ensuring cutting efficiency and cutting quality, it significantly reduces equipment cost.

[0027] 5. The processing head of this invention is applicable to flame-assisted multi-focus laser cutting, which can obtain a laser beam with higher power density and smaller divergence angle. This allows for both positive and negative defocus cutting during laser cutting, resulting in higher laser beam energy density at the bottom of the workpiece. Compared with single-focus flame-assisted laser cutting, it has greater advantages in cutting thick metal workpieces. At the same laser power level, it has higher cutting efficiency, better cutting quality, and greater cutting thickness. Under the premise of the same metal plate thickness, cutting efficiency, and cutting quality, a lower laser power (less than 2 kilowatts) can be used. Compared with the prior art that requires 6 kilowatts or even tens of thousands of watts of laser power, this invention will greatly reduce the laser power without affecting cutting efficiency and quality, achieving a qualitative breakthrough in the field. Attached Figure Description

[0028] Figure 1This is a perspective view of a modular laser cutting head with replaceable cutting nozzles provided in an embodiment of the present invention;

[0029] Figure 2 This is a front view of a modular laser cutting head with replaceable cutting nozzles provided in an embodiment of the present invention;

[0030] Figure 3 yes Figure 2 AA section view;

[0031] Figure 4 This is a schematic diagram of the structure of the laser cutting head body provided in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the structure of the protective mirror assembly provided in an embodiment of the present invention;

[0033] Figure 6 yes Figure 5 AA section view;

[0034] Figure 7 This is a schematic diagram of the collimating lens assembly provided in an embodiment of the present invention;

[0035] Figure 8 yes Figure 7 BB cross-sectional view;

[0036] Figure 9 This is a schematic diagram of the focusing lens assembly provided in an embodiment of the present invention;

[0037] Figure 10 yes Figure 9 AA section view;

[0038] Figure 11 This is a schematic diagram of the structure of the laser beam focusing unit provided in an embodiment of the present invention;

[0039] Figure 12 yes Figure 11 AA section view;

[0040] Figure 13 This is a schematic diagram of the structure of the cutting nozzle unit provided in an embodiment of the present invention;

[0041] Figure 14 yes Figure 13 BB cross-sectional view;

[0042] Figure 15 This is a schematic diagram of the mounting base provided in an embodiment of the present invention;

[0043] Figure 16 This is a schematic diagram of the structure of the flame-assisted laser cutting nozzle provided in an embodiment of the present invention;

[0044] Figure 17 This is a schematic diagram of the gas mixing unit of the flame-assisted laser cutting nozzle provided in an embodiment of the present invention.

[0045] Figure 18 This is a schematic diagram of the structure of the laser cutting nozzle provided in an embodiment of the present invention;

[0046] Figure 19 This is a schematic diagram of the structure of the plano-convex bifocal focusing lens provided in an embodiment of the present invention;

[0047] Figure 20 This is a side view of the plano-convex bifocal focusing lens provided in an embodiment of the present invention.

[0048] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0049] 1. Fiber optic connector; 2. Aviation connector; 3. Main cooling water channel; 7. Cooling water channel; 8. Protective lens cover; 9. Observation window; 10. Signal interface; 11. Laser cutting head body; 12. Laser beam focusing unit, 12-1 front bearing seat, 12-2 front bearing, 12-3 guide rail, 12-4 guide rail slider, 12-5 guide rail connecting plate, 12-6 lead screw, 12-7 rear bearing seat, 12-8 rear bearing, 12-9 bearing lock nut, 12-10 coupling, 12-11 motor seat, 12-12 motor; 13. Optical system unit; 14. Cutting nozzle unit, 14-1 upper body, 14-2 lower body, 14-3 cutting nozzle, 14-4 nozzle lock nut, 14-5 nut, 14-6 ceramic ring, 14-7 sensing nozzle, 14-8 spring probe, 14-9 connector, 14-10 combustion gas channel, 14-1 1. Laser Channel One; 14-12. Combustion-supporting Gas Channel; 14-13. Cutting Gas Channel One; 14-14. Mixing Structure; 14-15. Inlet Structure; 14-16. Laser Channel Two; 14-17. Cutting Gas Channel Two; 15. Protective Mirror Assembly; 15-1. Protective Mirror Connecting Plate; 15-2. Protective Mirror Mount; 15-3. Protective Mirror Clamping Ring; 15-4. Protective Mirror; 15-5. Sealing Ring; 16. Collimating Mirror Assembly; 16-1. Scale; 16-2. Collimating Mirror Mount; 16-3. Collimating Mirror; 16-4. Clamping Nut; 16-5. Mirror Mount Connector; 17. Focusing Mirror Assembly; 17-1. Adjusting Rod; 17-2. Mirror Mount Connecting Plate; 17-3. Positioning Plate; 17-4. Elastic Mounting Component; 17-5. Focusing Mirror; 17-6. Clamping Nut; 17-7. Focusing Mirror Mount; 18. Lower Connecting Seat; 19-1. Nozzle Body; 19-2. Mixing Gas Channel. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0051] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0053] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0054] like Figure 1-3As shown, this embodiment of the invention provides a modular laser cutting head with replaceable cutting nozzles, comprising a laser cutting head body 11, a laser beam focusing unit 12, an optical system unit 13, a connecting unit 18, and a cutting nozzle unit 14. The laser beam focusing unit 12 is mounted on the laser cutting head body 11 and is used to adjust the focal position of the laser beam. The optical system unit 13, connecting unit 18, and cutting nozzle unit 14 are arranged sequentially from top to bottom. The optical system unit 13 is located inside the laser cutting head body 11 and is used to shape, transform, and focus the externally input laser beam, guiding the focused laser beam to the connecting unit 18. The connecting unit 18 is connected to the lower end of the laser cutting head body 11 and is located directly below the optical system unit 13, guiding the laser beam to the cutting nozzle unit 14. The cutting nozzle unit 14 is detachably mounted on the lower end of the connecting unit 18, guiding the laser beam, cutting gas, combustion gas, and combustion-supporting gas to the surface of the workpiece to be cut, thereby achieving the cutting of the workpiece. The interchangeable nozzle combination laser cutting head provided by this invention is particularly suitable for cutting carbon steel materials of various thicknesses.

[0055] like Figure 4 As shown, the main body 11 of the laser cutting head is a frame structure, serving as the mounting base for the entire cutting head and integrating and connecting other functional units. For example... Figure 3 As shown, the optical system unit 13 is located in the middle of the entire laser cutting head body 11 and runs through the laser cutting head body 11. The input laser beam is transformed by the optical system unit 13 and then acts on the workpiece to be cut. Specifically, the laser cutting head body 11 has a laser beam transmission channel that runs from top to bottom. The optical system unit 13 is assembled in the laser beam transmission channel. In order to ensure that the laser beam is transmitted without obstruction throughout the entire laser cutting head body 11, the minimum aperture of the laser beam transmission channel must be larger than the laser beam spot diameter, and the laser beam transmission channel has a high degree of coaxiality. After passing through the laser beam transmission channel, the laser beam enters the cutting nozzle unit 14 through the connecting unit 18, and finally acts on the workpiece to be cut.

[0056] Specifically, such as Figure 3 As shown, the optical system unit 13 includes a collimating lens assembly 16 and a focusing lens assembly 17 arranged vertically. The collimating lens assembly 16 is used to collimate the laser beam, and the focusing lens assembly 17 is used to focus the laser beam. Further, as... Figure 7 and Figure 8As shown, the collimating lens assembly 16 includes a collimating lens mount 16-2 and a collimating lens 16-3. The collimating lens mount 16-2 has a lens mounting slot, and the collimating lens 16-3 is installed in the lens mounting slot of the collimating lens mount 16-2 by a clamping nut 16-4. It is used to collimate the laser beam, expanding and transforming the laser beam with a certain divergence angle into a parallel beam. The collimating lens mount 16-2 is also connected to a lens mount connector 16-5, through which the collimating lens mount 16-2 is connected to the laser beam focusing unit 12. Specifically, the collimating lens mount 16-2 is also provided with a dynamic focusing scale 16-1, used to observe the movement distance of the collimating lens mount 16-2 during dynamic focusing and to calculate the position of the laser beam focal point.

[0057] like Figure 3 As shown, the focusing lens assembly 17 is positioned below the collimating lens assembly 16, preferably 30mm to 200mm below the collimating lens assembly 16. That is, the distance between the focusing lens mount 17-7 and the collimating lens mount 16-2 is 30mm to 200mm. Using these parameters allows for a reduction in the size of the cutting head while ensuring sufficient space for the focusing lens installation. Figure 9 and Figure 10 As shown, the focusing lens assembly 17 includes a focusing lens 17-5, a focusing lens mount 17-7, a mount connecting plate 17-2, and an elastic mounting member 17-4. The focusing lens 17-5 is installed in the focusing lens mount 17-7 by a clamping nut 17-6. A mounting groove is provided on the outer circumference of the focusing lens mount 17-7. The elastic mounting member 17-4 is arranged around the outer circumference of the focusing lens mount 17-7 and is embedded in the mounting groove. Both ends of the elastic mounting member 17-4 are fixed to the mount connecting plate 17-2, thereby securing the entire focusing lens mount 17-7. A positioning plate 17-3 is also provided on the side of the focusing lens mount 17-7 facing the mount connecting plate 17-2. A positioning groove that mates with the positioning plate 17-3 is provided on the mount connecting plate 17-2. Through the cooperation of the positioning plate and the positioning groove, accurate positioning between the focusing lens mount 17-7 and the mount connecting plate 17-2 is achieved. In addition, an adjusting rod 17-1 is installed on the lens mount connecting plate 17-2. The lower end of the adjusting rod 17-1 abuts against the outer side of the focusing lens mount 17-7, thereby adjusting the distance and angle between the focusing lens mount 17-7 and the lens mount connecting plate 17-2 by moving the adjusting rod 17-1 up and down. The lens mount connecting plate 17-2 is detachably connected to the laser cutting head body 11. For example, the lens mount connecting plate 17-2 is fixed to the side of the laser cutting head body 11 by bolts, so that the entire focusing lens assembly is installed on the laser cutting head body 11. By removing the bolts, the focusing lens assembly 17 can be removed as a whole for easy lens replacement.

[0058] Specifically, the elastic mounting component 17-4 is preferably a spring, which uses its elasticity to hold the focusing lens mount 17-7 in place. When the adjusting rod retracts, the spring's elasticity allows the focusing lens mount 17-7 to return to its original position. The adjusting rod 17-1 can be a hex socket head cap screw. By rotating the hex socket head cap screw, the length of the screw extending beyond the lens mount connecting plate 17-2 can be adjusted, thereby adjusting the distance and angle between the focusing lens mount 17-7 and the lens mount connecting plate 17-2, thus adjusting the position of the focusing lens 17-5 and achieving concentricity adjustment between the focusing lens 17-5 and the collimating lens 16-3. To ensure assembly reliability, two elastic mounting components 17-4 are provided. To allow the focusing lens mount 17-7 to be adjusted throughout the entire mounting plane, two adjusting rods 17-1 are provided, located on both sides of the positioning plate 17-3, and each adjusting rod 17-1 can be adjusted independently.

[0059] like Figure 3 As shown, a protective mirror assembly 15 is disposed above the collimating lens assembly 16 and below the focusing lens assembly 17. This protective mirror assembly 15 is used to prevent dust from entering the beam transmission channel and damaging optical components during fiber insertion / removal and during laser head operation. The protective mirror assembly 15 is located within the laser beam transmission channel of the laser cutting head body 11. Figure 5 and Figure 6 As shown, the protective lens assembly 15 includes a protective lens base 15-2 and a protective lens 15-4. The protective lens 15-4 is mounted on the protective lens base 15-2 via a fixing assembly. The protective lens base 15-2 is connected to a protective lens connecting plate 15-1. The protective lens connecting plate 15-1 is detachably connected to the laser cutting head body 11. For example, the protective lens connecting plate 15-1 is fixed to the side of the laser cutting head body 11 by bolts, thereby allowing the entire protective lens assembly to be mounted on the laser cutting head body 11. By removing the bolts, the entire protective lens assembly can be removed for easy lens replacement. Specifically, the fixing assembly includes a protective lens clamping ring 15-3 and a sealing ring 15-5. The protective lens clamping ring 15-3 and the sealing ring 15-5 are respectively located on the upper and lower surfaces of the protective lens 15-4 and are assembled in the protective lens base 15-2. Specifically, one or more protective lens assemblies 15 can be used to protect the lenses in the straight lens assembly 16 and the focusing lens assembly 17. In this invention, two protective lens assemblies 15 are used to provide double-layer protection for the straight lens assembly 16 and the focusing lens assembly 17.

[0060] Furthermore, the laser beam is provided by a laser. In this invention, a laser capable of outputting a small divergence angle is preferably used. The divergence half-angle of the laser beam is 2° to 8°, and the collimating lens 16-3 and the focusing lens 17-5 are preferably short focal length lenses. By using a small divergence angle laser beam in conjunction with a shorter focal length collimating lens and focusing lens, while ensuring a sufficiently large depth of focus, the laser beam spot diameter is made smaller. This makes it possible for the laser beam focus to act below the surface of the workpiece to be cut (i.e., negative defocus, with the focus located inside the workpiece to be cut). This significantly increases the power density of the laser beam entering the kerf, resulting in a higher temperature, lower viscosity, and easier removal of the molten metal inside the kerf by high-pressure gas, thus achieving better cutting quality and processing efficiency.

[0061] Specifically, the laser can be a fiber laser, a disc laser, a diode-pumped solid-state laser, a high-power gas laser, or a semiconductor laser, etc., with fiber lasers being preferred. Preferably, the fiber core diameter of the fiber laser is 1μm to 100μm, more preferably 10μm to 50μm, and the power of the fiber laser is 1kW to 100kW, more preferably 2kW to 20kW. Using a small core diameter laser helps to reduce the divergence angle of the laser beam, thereby obtaining a laser beam with a larger depth of focus. With the fiber laser possessing the above parameters, a laser beam with a divergence half-angle of 2° to 8° can be obtained.

[0062] Furthermore, the collimating lens 16-3 has a diameter no greater than 60mm and a focal length no greater than 200mm, and the focusing lens 17-5 has a diameter no greater than 60mm and a focal length no greater than 600mm. More preferably, the collimating lens 16-3 has a diameter of 25mm–60mm and a focal length of 50mm–200mm, corresponding to a distance of 50mm–200mm from the collimating lens mount 16-2 to the fiber optic connector 1; the focusing lens 17-5 has a diameter of 25mm–60mm and a focal length of 100mm–600mm, corresponding to a distance from the focusing lens 17-5 to the focal point of the laser beam. Using these parameters allows the laser beam to pass through the cutting nozzle without energy loss. Even further, the protective lens 15-4 has a diameter of 15mm–60mm, and the distance between the collimating lens 16-3 and the focusing lens 17-5 is 30mm–200mm. In a preferred embodiment of the present invention, the diameters of the protective lens 15-4, collimating lens 16-3, and focusing lens 17-5 are 37 mm, the focal length of the collimating lens is 100 mm, the distance between the collimating lens and the focusing lens is 50 mm, and the focal length of the focusing lens is 400 mm. Both surfaces of the protective lens 15-4, collimating lens 16-3, and focusing lens 17-5 are coated with an anti-reflection film that is the same as or similar to the wavelength of the laser beam. This increases the transmittance of the laser beam, preventing reflection from optical components and thus avoiding energy loss or even damage to the optical components. All lens mounts and the fixed contact surfaces with the laser cutting head body 11 are equipped with sealing rings to prevent dust from entering the laser cutting head body 11 during cutting and contaminating or damaging the optical components.

[0063] Furthermore, the optical system unit 13 is replaceable; specifically, the collimating lens, focusing lens, and protective lens within the optical system unit 13 are replaceable. More specifically, the collimating lens, focusing lens, and protective lens in this invention can all be removed from their mounts via a plug-and-play method for inspecting the optical system for damage or contamination, in order to replace the lenses. For example, as... Figure 4As shown, horizontally arranged mounting slots are provided on the side of the laser cutting head body 11 for the corresponding positions of the protective lens assembly 15, collimating lens assembly 16, and focusing lens assembly 17. Each component, including the protective lens assembly 15, collimating lens assembly 16, and focusing lens assembly 17, can be inserted entirely into the mounting slots, making replacement very convenient. For the protective lens assembly 15 and focusing lens assembly 17, after insertion, the corresponding lens mount connecting plate is detachably installed on the laser cutting head body 11 to secure the components. For the collimating lens assembly 16, after insertion, the laser beam focusing unit 12 is assembled onto the laser cutting head body 11, and the lead screw 12-6 in the laser beam focusing unit 12 is threaded into the lens mount connecting body 16-5 in the collimating lens assembly 16 to install the collimating lens assembly 16. Specifically, a protective lens cover 8 is also provided on the side of the laser cutting head body 11. The protective lens cover 8 can cover the mounting slots to prevent contamination of the lens. The laser cutting head body 11 is also provided with an observation window 9, which is used to observe the distance the collimating lens moves during the focusing process, so as to calculate the actual moving distance of the laser beam focus.

[0064] Preferably, the focusing lens 17-5 is a multifocal focusing lens, which can be a single lens, a combination of lenses, or even a diffractive, reflective, or metallic lens. Its main function is to transform the collimated parallel beam into a laser beam with multiple focal points distributed along the optical axis. This invention preferably uses a single plano-convex lens, which has the advantages of simple structure, ease of implementation, and low cost. Furthermore, the multifocal laser beam generated by this lens has a more uniform energy distribution, resulting in a smoother cutting surface, better perpendicularity, and faster cutting speed. The multifocal focusing lens focuses a perpendicularly incident parallel beam into a beam with multiple focal points (P1, P2, ..., P...) along the optical axis. N A multifocal laser beam can be designed with the spacing and energy levels of each focal point customized to meet specific needs. Depending on the thickness of the metal sheet being cut, the focal points of the multifocal laser beam can be located on the top, surface, or interior of the workpiece.

[0065] like Figure 19 and Figure 20 As shown, the multifocal focusing lens is a plano-convex lens, with a flat lower surface and a convex upper surface. The convex surface is composed of multiple focal surfaces with different curvatures, and the curvature of each focal surface gradually increases from the center of the multifocal focusing lens outwards. Adjacent focal surfaces are connected by transition surfaces. Specifically, there are N focal surfaces and N-1 transition surfaces, where N is the number of focal points of the multifocal laser beam, and N≥2. That is, the convex surface of the multifocal focusing lens is designed to have multiple different surfaces from the lens center along the edge direction, i.e., it consists of 2N-1 different surfaces, including N focal surfaces and N-1 transition surfaces connecting the focal surfaces.

[0066] More specifically, taking the center of the focusing lens plane as the origin, let the equation of the surface be y. i =g(r i ), where y is the thickness from the convex surface of the focusing lens to the plane (g(0) = H), and the surface equations y of each surface (including the focal surface and the transition surface) are... i Determine using the following formula (1):

[0067]

[0068] Among them, y i Let f be the surface equation of surface i, n be the refractive index of the multifocal focusing lens, and f be the surface equation of surface i. i Let r be the focal length corresponding to surface i. i Let be the distance from the edge of surface i to the optical axis of the multifocal focusing mirror (maximum value is D / 2, where D is the diameter of the multifocal focusing mirror), H is the center thickness of the multifocal focusing mirror, i = 1, 2, 3, ..., 2N-1, where the surface located at the center of the multifocal focusing mirror is the focal surface, defined as the first surface, and the surface located at the outermost edge of the multifocal focusing mirror is defined as the second (N-1)th surface. That is, from the center of the multifocal focusing mirror outwards, the surfaces are numbered 1, 2, 3, ..., 2N-1, and the first, third, fifth, ..., 2N-1 are focal surfaces, while the second, fourth, sixth, ..., 2N-2 are transition surfaces.

[0069] Furthermore, the focal length of the focal surface and the distance from the edge of the focal surface to the optical axis of the multifocal focusing mirror can be preset according to actual needs. The focal length of the transition surface is determined by the following formula (2) based on the focal lengths of the focal surfaces before and after the transition and the distance from the edge of the focal surface to the optical axis of the multifocal focusing mirror:

[0070]

[0071] Among them, f k-1 Let r be the focal length of surface k-1 (i.e., the focal length corresponding to each focal surface). k-1 Let be the distance from the edge of surface k-1 to the optical axis of the multifocal focusing mirror (i.e., the distance from the edge of each focal surface to the optical axis of the multifocal focusing mirror), and r be the distance from the edge of the transition surface to the optical axis of the multifocal focusing mirror, r∈[r k-1 r k+1 ], that is, r takes values ​​within the range of distances from the edges of the front and rear focal surfaces to the optical axis of the multifocal focusing mirror, k = 2, 4, 6, ..., 2N-2.

[0072] Substituting n, H, and the focal length values ​​corresponding to different surfaces into formula (1), the surface equations y of each surface on the convex surface of the multifocal focusing mirror can be calculated. i =g(r iThe collimated parallel beam is transmitted to different curved surfaces on the convex surface of the focusing lens. These surfaces have different f-values, focusing the laser beam to different positions on the optical axis. Surfaces 1, 3, 5, ..., 2N-1 are focal surfaces, forming N focal points. Surfaces 2, 4, 6, ..., 2N-2 are transition surfaces, with their focal lengths gradually changing within the range of adjacent focal surfaces. Changing the focal length of the focal surfaces and the distance from their edges to the optical axis of the multifocal focusing lens alters the relative positions of the focal points and the beam energy at each focal point and in the focal transition zone.

[0073] like Figure 19 As shown, a bifocal focusing lens is provided. The bifocal focusing lens is a plano-convex lens, and its convex surface has three different curved surfaces S1, S2, and S3 along the edge direction from the center of the lens. The focal lengths of the two focal points (P1, P2) of the bifocal focusing lens are 400mm and 420mm, respectively. Curved surface S1 is the focal surface corresponding to the focal length of 420mm, and curved surface S3 is the focal surface corresponding to the focal length of 400mm. Curved surface S3 is a transition surface connecting the two focal surfaces. The diameter of the focusing lens is set to 37mm, the center thickness to 8mm, and the refractive index of the material to 1.45. The radii r1 and r3 of curved surfaces S1 and S3 are 3mm and 7mm, respectively. Substituting the above parameters into formula (1) can calculate the equation y1(r) of curved surface S1 and the equation y3(r) of curved surface S3. In addition, substituting the above parameters into formula (2) can calculate the focal length of the transition surface S2. Where 3≤r≤7, and then substituting the focal length of the transition surface S2 into formula (1), we can obtain the equation y2(r) of the transition surface S2. Using the three surface equations y1(r), y2(r) and y3(r), we can model the F400-F420 bifocal focusing lens, such as Figure 2 As shown, the lens model is imported into optical simulation software (such as Zemax) for optical simulation. If the lens model meets the actual requirements, it can be manufactured according to the engineering drawings of the output lens model.

[0074] Depending on the thickness of the workpiece to be cut, different refractive indices, radii of curvatures, and the number and area of ​​surfaces can be selected to change the spacing and number of focal points of the multifocal laser beam, as well as the energy at each focal point. Furthermore, to ensure sufficient energy and a suitable distribution within the workpiece, the number of focal points N and the spacing S should not be too large. When cutting thick metal materials, the focal points of the laser beam should be located as much as possible within the workpiece 7 to effectively overcome problems such as severe slag buildup caused by insufficient laser beam energy at the bottom of the material when cutting thick metal materials with a single-focal laser beam. Furthermore, to ensure the multifocal laser beam passes through the cutting nozzle without energy loss and that the focal point of the laser beam is located inside the workpiece to be cut, while simultaneously ensuring uniform energy distribution at each focal point to accommodate the cutting of metal materials of varying thicknesses, the focal length of the focal surface at the center of the multifocal focusing lens is 200mm–600mm, preferably 300mm–500mm; the number of focal points is 2–8, preferably 2–4; the distance between adjacent focal points is 5mm–50mm, preferably 10mm–40mm; and the light-transmitting area of ​​the other focal surfaces is 1–3 times that of the focal surface at the center of the multifocal focusing lens. Through the above design, combined with the relevant parameter design of the collimating lens, the multifocal laser beam… The laser beam's focal points, partially or entirely, act below the workpiece surface, enabling both positive and negative defocus cutting. This results in higher energy density of the laser beam at the bottom of the workpiece, offering significant advantages over single-focus flame-assisted laser cutting for cutting thick metal workpieces. At the same laser power level, it achieves higher cutting efficiency, better cutting quality, and greater cutting thickness. Furthermore, with the same metal plate thickness, cutting efficiency, and cutting quality, it allows for the use of lower laser power (below 2 kilowatts). Compared to existing technologies requiring 6 kilowatts or even tens of thousands of kilowatts of laser power, this invention significantly reduces laser power without affecting cutting efficiency and quality, representing a qualitative breakthrough in the field.

[0075] The processing head of this invention enables flame-assisted multifocal laser cutting, achieving a laser beam with greater depth of focus and smaller divergence angle. This allows the laser beam to pass through the cutting nozzle's Laval structure without loss, even when the Laval structure is very narrow. Simultaneously, the narrow Laval structure continuously accelerates the cutting gas, ensuring that the oxygen concentration and flow rate in the workpiece area remain at a high level. This results in a more complete oxygen-iron reaction, releasing more heat energy, better slag removal, and improved cutting speed and kerf quality. Furthermore, because the laser beam spot diameter is smaller, the Laval structure aperture at the bottom of the cutting nozzle can be correspondingly smaller, leading to lower cutting gas consumption and lower cutting costs under the same conditions. This invention's cutting head organically combines a multifocal laser beam and a Laval cutting nozzle, making it possible to cut thicker metal materials with lower laser power. It can cut metal materials of varying thicknesses, broadening its applicability.

[0076] like Figure 11 and Figure 12 As shown, the laser beam focusing unit 12 includes a motor 12-12, a lead screw 12-6, a guide rail 12-3, and a guide rail slider 12-4. The motor 12-12, serving as the power unit for the laser beam focusing unit 12, is mounted on the laser cutting head body 11 via a motor mount 12-11 and connected to the lead screw 12-6 via a coupling 12-10, driving the lead screw 12-6 to rotate. The lead screw 12-6 is threadedly engaged with the lens mount connector 16-5 in the collimating lens assembly. The guide rail 12-3 is mounted on the laser cutting head body 11 and slidably engages with the guide rail slider 12-4. The guide rail slider 12-4 is connected to the lens mount connector 16-5 via a guide rail connecting plate 12-5. When the motor 12-12 drives the lead screw 12-6, the collimating lens assembly 16 moves up and down under the guidance of the guide rail and guide rail slider, thereby adjusting the focal position of the laser beam by changing the spatial position of the lens. In addition, two limit sensors are installed on the guide rail 12-3. When the guide rail slider 12-4 moves to the limit sensor, the limit sensor will be triggered. At the same time, the limit sensor sends a sensing signal to the controller, causing the motor 12-12 to stop working, thereby controlling the movement stroke of the guide rail slider 12-4 and limiting the focusing range. In this invention, the focusing range is set to -20mm to 20mm.

[0077] To ensure the stability of the adjustment, a rear bearing 12-8 is installed at one end of the lead screw 12-6 near the motor 12-12. The rear bearing 12-8 is fixed to the laser cutting head body 11 by the combined action of the bearing locking nut 12-9 and the rear bearing seat 12-7. A front bearing 12-2 is installed at the other end of the lead screw 12-6. The front bearing 12-2 is connected to the laser cutting head body 11 through the front bearing seat 12-1. Specifically, an aviation connector 2 is installed on the main body 11 of the laser cutting head. The aviation connector 2 is connected to the motor 12-12 and an external controller. The external pulse signal input through the aviation connector 2 controls the start and stop of the motor 12-12. The motor 12-12 drives the lead screw 12-6 to move, and at the same time, it causes the collimating lens assembly 16 to move up and down. The guide rail 12-3 and the guide rail slider 12-4 are used to control the direction of movement, so that the collimating lens assembly 16 only moves up and down. When the spatial position of the collimating lens assembly 16 changes, the optical system unit 13 changes, causing the focal position of the laser beam to change, thereby realizing the adjustment of the laser beam focal point.

[0078] Depending on the connection between the guide rail slider 12-4 and different optical components, different focusing methods can be used. When the guide rail slider 12-4 is connected to the collimating lens assembly 16, it is called the collimating focusing method, while when it is connected to the focusing lens assembly 17, it is called the focusing focusing method. In this invention, the collimating focusing method is preferred, which is beneficial to reduce the movement stroke of the guide rail slider 12-4 during dynamic focusing, thereby shortening the overall size of the cutting head.

[0079] like Figure 13 and Figure 14 As shown, the cutting nozzle unit 14 includes a mounting base, a cutting nozzle 14-3, and a height sensing component. The cutting nozzle unit 14 is connected to the bottom of the lower connecting base 18 via the mounting base. The mounting base has a cutting gas channel 14-13, and also contains the connection lines for the height sensing component and a cooling water channel 7 for the cutting nozzle 14-3. The cooling water channel 7 is used to cool the cutting nozzle 14-3 during cutting, preventing damage due to overheating during prolonged cutting. The cutting nozzle 14-3 is mounted on the mounting base via a nozzle locking nut 14-4, and has a laser channel 14-11 that communicates with the cutting gas channel 14-13 on the mounting base.

[0080] Furthermore, the height sensing component can be a capacitive height adjustment component, an arc voltage height adjustment component, or a mechanical height adjustment component. Preferably, the height sensing component is a capacitive height adjustment component, including a ceramic ring 14-6, a sensing nozzle 14-7, a spring probe 14-8, and a connector 14-9. The ceramic ring 14-6 is mounted on the bottom of the mounting base by a nut 14-5 and is arranged around the cutting nozzle 14-3. The sensing nozzle 14-7 is mounted on the bottom of the ceramic ring 14-6 and is arranged around the cutting nozzle 14-3. The connector 14-9 is mounted on the mounting base and is connected to the spring probe 14-8 by a wire. The connector 14-9 and the spring probe 14-8 constitute the connection line of the height sensing component. The spring probe 14-8 is connected to the upper end of the ceramic ring 14-6, the lower end of the ceramic ring 14-6 contacts the sensing nozzle 14-7, and the spring probe 14-8 is electrically connected to the sensing nozzle 14-7. Specifically, the ceramic ring 14-6 includes an annular ceramic body surrounding the cutting nozzle 14-3. A through groove is formed on the annular ceramic body, and a metal connector is disposed within the through groove. The upper end of the metal connector is connected to the spring probe 14-8, and the lower end contacts the sensing nozzle 14-7, thereby achieving an electrical connection between the spring probe 14-8 and the sensing nozzle 14-7. Specifically, the metal connector includes a metal post (e.g., a copper post) and a metal rod connected to each other. The metal post is located at the upper end of the annular ceramic body, and the metal rod passes through the through groove. The metal post is connected to the spring probe, and the lower end of the metal rod contacts the sensing nozzle 14-7. More specifically, the connector 14-9 is connected to an external signal interface 10, such as... Figure 2 As shown, the signal interface 10 is located outside the laser cutting head body 11 and is used to connect to an external controller. A height sensor, composed of a ceramic ring 14-6 and a sensing nozzle 14-7, forms a capacitor with the metal workpiece to be cut. When the distance between the sensing nozzle 14-7 and the workpiece changes, the potential of the capacitor changes. This changing signal is transmitted to the external controller via a connecting line. The controller adjusts the height between the entire laser cutting head and the metal workpiece based on the received electrical signal, ensuring that the height of the sensing nozzle 14-7 above the workpiece surface remains constant, thus achieving constant-height cutting and effectively guaranteeing the stability of the cutting quality. Specifically, the connector 14-9 is a copper pillar, and both the spring probe 14-8 and the sensing nozzle 14-7 are made of metal materials, such as copper.

[0081] The combined laser cutting head of this invention is generally mounted on a machine tool or robot. The three-dimensional motion mechanism of the machine tool or robot drives the cutting head in three-dimensional motion, thereby cutting the workpiece along a predetermined path. During cutting, a height sensor composed of a ceramic ring 14-6 and a sensing nozzle 14-7 senses the height signal between the cutting head and the workpiece. The controller in the three-dimensional motion mechanism of the machine tool or robot moves the three-dimensional motion mechanism according to the signal transmitted by the height sensor, thereby adjusting the height of the cutting head relative to the workpiece, ensuring that the focal point of the laser beam remains at the same position on the workpiece throughout the cutting process. The cutting nozzle unit 14 is used to input and guide the laser beam and cutting gas, and also has the function of real-time monitoring of the height of the cutting head during the cutting process, ensuring that the distance between the cutting head and the surface of the workpiece remains essentially constant. Specifically, the mounting base can be an integral structure or a split structure, including an upper body 14-1 and a lower body 14-2, with the lower body 14-2 fitted onto the lower part of the upper body 14-1.

[0082] like Figure 15 As shown, the mounting base has a cutting gas channel 14-13, a combustion gas channel 14-10, and an auxiliary combustion gas channel 14-12. Cutting gas channel 14-13 is connected to an external cutting gas source to supply cutting gas to the cutting nozzle. Combustion gas channel 14-10 is connected to an external combustion gas source to supply combustion gas to the cutting nozzle. Auxiliary combustion gas channel 14-12 is connected to an external auxiliary combustion gas source to supply auxiliary combustion gas to the cutting nozzle. Cutting gas channel 14-13 is connected to the laser channel 14-11 on the cutting nozzle, allowing the cutting gas and laser beam to be transmitted together through the laser channel of the cutting nozzle to the surface of the workpiece to achieve cutting. When using a traditional laser cutting head for thin plate laser cutting, the cutting gas is generally oxygen, nitrogen, argon, or compressed air, and no combustion gas or auxiliary combustion gas is required. When using a flame-assisted laser cutting head for thick plate laser cutting, the cutting gas is generally ordinary oxygen or high-purity oxygen, while the combustion gas is generally an organic combustion gas such as propane, acetylene, or natural gas. The pressure of the combustion gas is generally lower than that of low-pressure oxygen, ranging from 0.05 bar to 0.4 bar. The combustion-supporting gas is low-pressure oxygen, with a pressure of 0.1 bar to 2 bar. This low-pressure oxygen acts as a combustion-supporting agent to react with the combustion gas to produce a high-temperature flame.

[0083] Specifically, such as Figure 16As shown, the cutting nozzle 14-3 is a flame-assisted laser cutting nozzle. The nozzle includes a nozzle body 19-1, and a laser channel 14-11 is located in the middle of the nozzle body 19-1 and is coaxially arranged with the nozzle body. The upper end of the laser channel 14-11 serves as the inlet for the cutting gas and laser beam, and the lower end serves as the outlet for the cutting gas and laser beam. The lower end is designed with a Laval structure. A mixed gas channel 19-2 is also provided on the nozzle body 19-1. The mixed gas channel 19-2 is located on the side of the nozzle body and is connected to the combustion gas channel 14-10 and the combustion-supporting gas channel 14-12 on the mounting base. It is used to output the mixed gas of combustion gas and combustion-supporting gas from the lower end of the nozzle body 19-1. By designing a Laval structure, the cutting gas is continuously accelerated as it passes through the structure, eventually reaching supersonic speed upon exit. This ensures that the cutting gas maintains high speed, purity, and stiffness across the entire workpiece thickness range, resulting in higher cutting efficiency and better slag removal. Furthermore, the slender Laval structure effectively reduces the nozzle diameter, significantly decreasing the consumption of the main cutting gas, thereby improving cutting quality while reducing cutting costs.

[0084] Specifically, the Laval structure exhibits either a contraction-then-straightening-then-expansion or a contraction-then-expansion structure. This invention preferentially uses the contraction-then-straightening-then-expansion structure, which includes a contraction section, a straightening section, and an expansion section arranged sequentially from top to bottom. More specifically, the total length of the Laval structure is 5mm to 50mm, the cone angle of the contraction section is 10° to 65°, the inner diameter of the straightening section is 0.9mm to 5mm, and the cone angle of the expansion section is 5° to 15°. Specifically, the Laval structure is integrally formed with the laser channel 14-11, or the Laval structure is an independent structure embedded inside the lower end of the laser channel 14-11. Preferably, the upper end of the mixed gas channel 19-2 is an annular groove, and the lower end has multiple vertically arranged strip grooves evenly distributed along the circumference of the nozzle body, with the strip grooves communicating with the annular groove.

[0085] Furthermore, the flame-assisted laser cutting nozzle may also include a gas mixing unit that is connected to the combustion gas passage 14-10 and / or the combustion-supporting gas passage 14-12 on the mounting base. For example... Figure 17 As shown, the gas mixing unit includes a gas mixing structure 14-14 and an air intake structure 14-15 connected to each other. The air intake structure 14-15 is used to send combustion gas and combustion-supporting gas into the gas mixing structure 14-14 through different inlets. The gas mixing structure 14-14 is used to mix the combustion gas and combustion-supporting gas and then send them into the mixed gas channel 19-2 through the combustion gas channel 14-10 and / or the combustion-supporting gas channel 14-12 on the mounting base.

[0086] Specifically, the intake structure 14-15 is an ejector-type structure, including two inlets: one for inputting combustion-supporting gas and the other for inputting combustion gas. The gas mixing structure 14-14 is provided with a mixing chamber, which includes a converging section, a straight section, and an expanding section arranged sequentially. The converging section serves as the input end for both combustion gas and combustion-supporting gas, the straight section as the mixing section, and the expanding section as the output end. Specifically, both inlets of the intake structure 14-15 are connected to the mixing chamber of the gas mixing structure 14-14. One inlet is located in the middle of the ejector-type structure for inputting combustion-supporting gas, and the other inlet surrounds the middle inlet for inputting combustion gas. The pressure of the combustion-supporting gas is higher than that of the combustion gas.

[0087] During cutting, the higher-pressure combustion gas first enters the gas mixing structure through one inlet of the ejector-type air intake structure, creating a certain degree of negative pressure at the inlet of the gas mixing structure. Then, the lower-pressure combustion gas is drawn into the gas mixing structure under this negative pressure environment and mixes with the combustion gas within the gas mixing structure to form a gas mixture. The gas mixture then flows into the gas mixing channel of the nozzle through the channel on the mounting base. The ejector-type structure of the cutting nozzle not only reduces the pressure of the combustion gas used for cutting, but also allows the longer gas mixing structure to provide a longer and more uniform mixing path for the combustion gas and combustion gas, resulting in more complete combustion of the gas mixture and the release of more heat energy. This effectively improves the cutting speed of metal sheets and the energy utilization rate during the cutting process.

[0088] Furthermore, the cutting nozzle 14-3 is a laser cutting nozzle, such as... Figure 18 As shown, the laser cutting nozzle includes a laser cutting nozzle body. A second laser channel 14-16 is located in the middle of the laser cutting nozzle body and is coaxially arranged with it. The upper end of the second laser channel 14-16 serves as the inlet for the cutting gas and laser beam, and the lower end serves as the outlet for the cutting gas and laser beam. A second cutting gas channel 14-17 is also provided on the laser cutting nozzle body. The second cutting gas channel 14-17 is located on the side of the laser cutting nozzle body and surrounds the second laser channel 14-16. The second cutting gas channel 14-17 is connected to the cutting gas channel on the mounting base; alternatively, the second laser channel 14-16 also serves as the cutting gas channel, meaning that the cutting gas and laser beam pass through the second laser channel 14-16 simultaneously.

[0089] The cutting nozzle unit 14 with the aforementioned flame-assisted laser cutting nozzle can achieve flame-assisted laser cutting of thick metal materials, and the cutting nozzle unit 14 with the aforementioned laser cutting nozzle can achieve laser cutting of thin sheet materials. When it is necessary to switch between the two cutting modes, simply replace the cutting nozzle unit 14 with the corresponding cutting nozzle. Since the cutting nozzle unit 14 is detachable, when it is necessary to change the cutting mode, the entire cutting nozzle unit 14 can be removed as a whole, and a cutting nozzle unit 14 with other modes can be installed. At the same time, the collimating lens, focusing lens, etc. in the optical system unit can be replaced as needed. Of course, since the nozzle and mounting base of this invention are detachably connected, and the height sensor (the integral unit consisting of ceramic ring 14-6 and sensing nozzle 14-7) is detachably connected to the mounting base, the cutting mode can be switched by first removing the height sensor, then removing the nozzle (e.g., a flame-assisted laser cutting nozzle), then replacing it with another nozzle (e.g., a laser cutting nozzle), and then reinstalling the height sensor. This combines the advantages of laser cutting of thin sheet metal with the advantages of flame-assisted laser cutting of thick sheet metal on the same laser cutting equipment, greatly expanding the applicability of the cutting head. Flame-assisted laser cutting nozzles and laser cutting nozzles are available in various models according to their diameter. Different types and models of cutting nozzles are selected based on the thickness of the workpiece to be cut. In actual operation, nozzles of any size and specification can be used, while the mounting base, height sensor, and air path can all be shared. The optical system unit can also be shared; only the focusing lens and collimating lens need to be replaced. Therefore, the versatility of the equipment and the range of cutting applications can be greatly improved, reducing equipment investment.

[0090] Furthermore, the laser processing cutting head provided by the present invention also includes a cooling unit, which includes a main cooling water channel 3. The main cooling water channel 3 is located on both sides of the laser cutting head body 11. The two cooling water channels form a loop inside the laser cutting head body 11 to cool the laser cutting head body 11 and the optical system unit 13, so as to prevent the cutting head components from being damaged due to excessive local temperature during the cutting process.

[0091] Furthermore, the laser cutting head body 11 is also equipped with a fiber optic connector 1. The fiber optic connector 1 can adopt a standard connector type (such as QBH, QCS, and QD) for connecting to an external laser and guiding the laser beam emitted by the laser to the optical system unit 13. The fiber optic connector 1 is located at the top center of the laser cutting head body 11. The fiber optic interface of the laser is inserted into the fiber optic connector 1 and fixed and locked. The fiber optic connector 1 guides the laser beam output from the fiber optic cable into the optical system unit 13.

[0092] In the flame-assisted laser cutting mode, the cutting head provided by this invention first introduces combustion gas and low-pressure oxygen into the mixed gas channel 19-2 of the cutting nozzle 14-3 via the combustion gas channel 14-10 and the combustion-supporting gas channel 14-12 before cutting begins. The two gases mix and are then delivered through the mixed gas channel 19-2 to the bottom of the cutting nozzle 14-3, where they are ignited to generate a high-temperature flame. Subsequently, the cutting oxygen and laser beam are output through the laser channel 14-11 of the cutting nozzle 14-3 to the surface of the workpiece to be cut. Unlike the flame-assisted laser cutting mode, in the laser cutting mode, after changing the cutting nozzle unit 14 or the cutting nozzle 14-3, only the cutting gas and laser beam need to be output to the surface of the workpiece through the cutting nozzle; there is no need to introduce combustion gas and combustion-supporting gas. Furthermore, when using the laser cutting mode for thin plate cutting, the cutting gas can be not only ordinary oxygen or high-purity oxygen, but also nitrogen, argon, or even compressed air. However, when using gas-assisted laser cutting, the cutting gas is generally ordinary oxygen or high-purity oxygen.

[0093] The following are embodiments of the present invention.

[0094] Example 1

[0095] When using the combined laser cutting head provided by this invention for flame-assisted laser cutting, a flame-assisted laser cutting nozzle is installed, and the combined laser cutting head is mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 6 mm, and the cutting gas is 9 bar high-pressure oxygen. The diameter of the protective lens in the optical system unit is 38 mm, the diameter of the collimating lens is 38 mm, the focal length is 100 mm, the diameter of the focusing lens is 37 mm, and the focal length is 500 mm. A 6 kW fiber laser with a core diameter of 50 μm and a beam quality (BPP) of 1.96 is used as the light source. After the laser beam emitted by the laser with the above parameters passes through the optical system composed of the collimating lens and the focusing system, and then through the composite cutting head, its focal point is located below the workpiece surface. Simultaneously, the focal point of the laser beam is adjusted by the dynamic adjustment unit to be located 20 mm below the workpiece surface.

[0096] Propane and oxygen are then introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, with the gas pressures set to 0.4 bar and 0.5 bar respectively. After mixing, the input propane and oxygen are ignited at the outlet of the flame-assisted cutting nozzle, generating a high-temperature flame that heats the workpiece to be cut. The cutting function is then activated, with a focused laser beam of a certain power and 9 bar high-pressure oxygen input into the laser channel of the cutting nozzle. Simultaneously, the combined laser processing head moves along the preset cutting path under the drive of the machine tool. Based on the capacitance signal generated by the height difference between the sensing nozzle of the processing head and the workpiece, the machine tool adjusts the height between the processing head and the workpiece in real time, keeping the processing head 6 mm above the workpiece surface. Finally, flame-assisted laser cutting of a 60 mm thick metal material is achieved at a speed of 0.9 m / min.

[0097] Example 2

[0098] When using the combined laser cutting head provided by this invention for laser cutting, the cutting nozzle of the combined laser cutting head is replaced with a laser cutting nozzle. The combined laser cutting head is installed on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The cutting path is set and the nozzle height is set to 1mm. The cutting gas is 2 bar oxygen. The laser is a fiber laser with a power of 4kW, a core diameter of 50μm, and a beam quality (BPP) of 1.3. The diameter of the protective lens in the optical system unit is 30mm, the diameter of the collimating lens is 30mm, the focal length is 100mm, and the diameter of the focusing lens is 30mm, the focal length is 200mm. With the laser and optical system configured with the above parameters, the focal point of the laser beam is located below the surface of the workpiece. At the same time, the focal point of the laser beam is located 3mm below the surface of the workpiece through the adjustment of the dynamic adjustment unit.

[0099] The cutting function is then activated, and a laser beam of a certain power and 2 bar of cutting oxygen are input into the laser channel of the cutting nozzle. At the same time, the combined laser processing head moves along the preset cutting path. The machine tool adjusts the height between the processing head and the workpiece in real time based on the capacitance value generated by the height difference between the sensing nozzle of the processing head and the workpiece, keeping the processing head 1 mm above the workpiece surface. Finally, the laser cutting of low carbon steel with a thickness of 8 mm is achieved at a speed of 2 m / min.

[0100] Example 3

[0101] Using the combined laser cutting head provided by this invention, perforation and cutting are performed on a 30mm thick low-carbon steel plate using flame-assisted laser cutting. First, the flame-assisted laser cutting nozzle is installed inside the combined laser cutting head. The combined laser cutting head is then mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 5mm, the cutting gas is 7bar oxygen, and the laser is a 4kW fiber laser with a core diameter of 50μm and a beam quality (BPP) of 1.3. The diameter of the protective lens in the optical system unit is 38mm, the diameter of the collimating lens is 38mm, the focal length is 150mm, and the diameter of the focusing lens is 38mm, the focal length is 400mm. With the laser and optical system configured with the above parameters, the focal point of the laser beam is positioned below the workpiece surface. Simultaneously, the focal point of the laser beam is adjusted by the dynamic adjustment unit to be 10mm below the workpiece surface.

[0102] Subsequently, 0.4 bar of propane and 0.6 bar of oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel. After the two gases are mixed, they are ignited at the outlet of the flame cutting nozzle to generate a high-temperature flame. Then, a laser beam and cutting oxygen at a pressure of 7 bar are input into the laser channel of the cutting nozzle to pierce the predetermined position. The workpiece is then cut along the preset cutting path at a speed of 0.9 m / min.

[0103] Example 4

[0104] The combined laser cutting head provided by this invention is used to cut a 30mm thick low-carbon steel plate using an ejector-type flame-assisted laser cutting nozzle. First, the flame-assisted laser cutting nozzle is installed inside the combined laser cutting head. The combined laser cutting head is then mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The cutting gas used is 7 bar cutting oxygen, the nozzle height is set to 5mm, and the laser is 3kW with a core diameter of 14μm and a beam quality of M. 2 The fiber laser is 1.1. The diameter of the protective lens in the optical system unit is 30mm, the diameter of the collimating lens is 30mm, the focal length is 150mm, the diameter of the focusing lens is 30mm, and the focal length is 400mm. The laser and optical system with the above parameters make the focal point of the laser beam located below the surface of the workpiece. At the same time, the dynamic adjustment unit adjusts the focal point of the laser beam to be located 10mm below the surface of the workpiece.

[0105] Subsequently, 0.1 bar of propane and 1 bar of oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel. After the two gases are mixed, they are ignited at the outlet of the flame cutting nozzle to generate a high-temperature flame. Then, a laser beam and cutting oxygen at a pressure of 7 bar are input into the laser channel of the cutting nozzle to pierce the predetermined position. The workpiece is then cut along the preset cutting path at a speed of 1 m / min.

[0106] Example 5

[0107] Using the combined laser cutting head provided by this invention, a flame-assisted laser cutting mode is employed to cut non-ferrous metals such as copper or copper alloys with a thickness of 12mm. Before starting cutting, a flame-assisted laser cutting nozzle is installed, and the combined laser cutting head is mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 4mm, the cutting gas is oxygen at a pressure of 12 bar, and the laser is a 1kW green or blue laser. In the optical system unit, the diameter of the protective lens is 32mm, the diameter of the collimating lens is 32mm, the focal length is 100mm, and the diameter of the focusing lens is 32mm, the focal length is 300mm. With the laser and optical system configured according to the above parameters, the focal point of the laser beam is positioned below the workpiece surface. Simultaneously, the dynamic adjustment unit is used to adjust the focal point of the laser beam to 5mm below the workpiece surface.

[0108] Propane and oxygen are then introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, with the gas pressures set to 0.4 bar and 0.5 bar respectively. After mixing, the input propane and oxygen are ignited at the outlet of the flame-assisted cutting nozzle, generating a high-temperature flame that heats the workpiece to be cut. Subsequently, a 1 kW green or blue laser beam and 12 bar high-pressure oxygen are input into the laser channel of the cutting nozzle. Simultaneously, the combined laser processing head moves along the preset cutting path under the drive of the machine tool. The machine tool adjusts the height between the processing head and the workpiece in real time based on the capacitance signal generated by the height difference between the sensing nozzle of the processing head and the workpiece, keeping the processing head 4 mm above the workpiece surface. Finally, flame-assisted laser cutting of copper or copper alloy with a thickness of 12 mm is achieved at a speed of 450 mm / min.

[0109] Example 6

[0110] The combined laser cutting head provided by this invention employs a flame-assisted laser cutting mode to cut non-ferrous metals such as aluminum or aluminum alloys with a thickness of 20mm. Before starting cutting, a flame-assisted laser cutting nozzle is installed, and the combined laser cutting head is mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 3.5mm, the cutting gas is high-pressure oxygen at a pressure of 10 bar, and the laser is a 3kW infrared fiber laser. In the optical system unit, the diameter of the protective lens is 32mm, the diameter of the collimating lens is 32mm, the focal length is 100mm, and the diameter of the focusing lens is 32mm, the focal length is 300mm. With the laser and optical system configured according to the above parameters, the focal point of the laser beam is located below the workpiece surface. Simultaneously, the dynamic adjustment unit is used to adjust the focal point of the laser beam to be 7mm below the workpiece surface.

[0111] Propane and oxygen are then introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, with the gas pressures set to 0.4 bar and 0.5 bar respectively. After mixing, the input propane and oxygen are ignited at the outlet of the flame-assisted cutting nozzle, generating a high-temperature flame that heats the workpiece to be cut. Subsequently, a laser beam and 10 bar high-pressure oxygen are input into the laser channel of the cutting nozzle. Simultaneously, the combined laser processing head moves along the preset cutting path under the drive of the machine tool or robot. The machine tool adjusts the height between the processing head and the workpiece in real time based on the capacitance signal generated by the height difference between the sensing nozzle of the processing head and the workpiece, keeping the processing head 3.5 mm above the workpiece surface. Finally, flame-assisted laser cutting of aluminum or aluminum alloy is achieved at a speed of 500 mm / min.

[0112] Example 7

[0113] The combined laser cutting head provided by this invention is used to cut a 30mm thick Q235 low carbon steel plate using flame-assisted multifocal laser cutting. First, the flame-assisted laser cutting nozzle is installed inside the combined laser cutting head. The combined laser cutting head is then mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 4mm, the cutting gas is 7bar oxygen, and the laser is a 4kW fiber laser with a core diameter of 50μm and a beam quality (BPP) of 1.3. The diameter of the protective lens in the optical system unit is 38mm, the diameter of the collimating lens is 38mm, the focal length is 100mm, and the focusing lens is a 38mm diameter F400-F420 bifocal focusing lens. Through the laser and optical system with the above parameters, the laser beam output by the laser is transformed into a bifocal laser beam. At the same time, the F400 focal point of the bifocal laser beam is positioned 5mm below the workpiece surface by the adjustment of the dynamic adjustment unit.

[0114] Subsequently, 0.5 bar of propane and 0.4 bar of oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel. After the two gases are mixed, they are ignited at the outlet of the flame cutting nozzle to generate a high-temperature flame. Then, a dual-focus laser beam and cutting oxygen at a pressure of 7 bar are input into the laser channel of the cutting nozzle to pierce the predetermined position. The workpiece is then cut along the preset cutting path at a speed of 1.3 m / min. There is basically no slag on the bottom of the cut workpiece, the average roughness of the cut surface is about 25 μm, and the perpendicularity of the cut surface is about 87°.

[0115] Example 8

[0116] The combined laser cutting head provided by this invention is used to cut a 160mm thick Q235 low carbon steel plate using flame-assisted multifocal laser cutting. First, the flame-assisted laser cutting nozzle is installed inside the combined laser cutting head. The combined laser cutting head is then mounted on a machine tool or robot and connected to the corresponding controller of the machine tool or robot. The nozzle height is set to 6mm, the cutting gas is 10bar oxygen, and the laser is a 6kW fiber laser with a core diameter of 50μm and a beam quality (BPP) of 1.96. The diameter of the protective lens in the optical system unit is 38mm, the diameter of the collimating lens is 38mm, the focal length is 100mm, and the focusing lens is a 38mm diameter four-focal focusing lens with F400-F440-F480-F520. Through the laser and optical system with the above parameters, the laser beam output is transformed into a four-focal laser beam. At the same time, the F400 focal point of the four-focal laser beam is positioned 15mm below the workpiece surface through the adjustment of the dynamic adjustment unit.

[0117] Subsequently, 0.4 bar of propane and 0.5 bar of oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel. After the two gases are mixed, they are ignited at the outlet of the flame cutting nozzle to generate a high-temperature flame. Then, a four-focus laser beam and cutting oxygen at a pressure of 10 bar are input into the laser channel of the cutting nozzle to pierce the predetermined position. Then, the workpiece is cut along the preset cutting path at a speed of 0.4 m / min. There is basically no slag on the bottom of the cut workpiece, the average roughness of the cut surface is 45 μm, and the perpendicularity of the cut surface is 85°.

[0118] Comparative Example 1

[0119] Referring to Example 1 of patent CN201410160925.2 (A laser-flame composite cutting device), the laser-flame composite cutting device was used to perform laser-flame composite cutting on a Q235 low carbon steel plate with a thickness of 30mm. The laser power was 5.5kW, the propane pressure was 0.05MPa (0.5bar), the main cutting oxygen pressure was 0.25MPa (2.5bar), and the auxiliary combustion oxygen pressure was 0.04MPa (0.4bar). The laser focus was located 15mm above the surface of the steel plate, and the lower edge of the laser nozzle was 5mm away from the surface of the steel plate. Finally, the cutting speed was 1.0m / min until the steel plate was broken. The laser used was a 6kW dish solid-state laser with continuous wave laser output mode. The fiber diameter was 0.2mm, the collimation focal length was 200mm, and the focal length of the focusing lens was 600mm.

[0120] Comparative Example 2

[0121] Referring to Example 2 of patent CN201410160925.2 (A laser-flame composite cutting device), the laser-flame composite cutting device was used to perform laser-flame composite cutting on a Q235 low carbon steel plate with a thickness of 140mm. The laser power was 6kW, the propane pressure was 0.05MPa (0.5bar), the main cutting oxygen pressure was 0.35MPa (3.5bar), and the auxiliary combustion oxygen pressure was 0.04MPa (0.4bar). The laser focus was located 15mm above the surface of the steel plate, and the lower edge of the laser nozzle was 5mm away from the surface of the steel plate. Finally, the cutting speed was 0.3m / min until the steel plate was broken. The laser used was a 6kW dish solid-state laser with continuous wave laser output mode, fiber diameter of 0.2mm, collimation focal length of 200mm, and focal length of focusing lens of 600mm.

[0122] A comparison of Comparative Example 1 and Embodiment 7 of the present invention shows that the flame-assisted multi-focus laser cutting technology provided by the present invention, under the premise of the same workpiece thickness, can achieve the cutting of thick plates using lower laser power (4kW vs 5.5kW) and faster cutting speed (1.3m / min vs 1.0m / min). A comparison of Comparative Example 2 and Embodiment 8 of the present invention shows that, under the same laser power, the flame-assisted multi-focus laser cutting technology provided by the present invention can cut thicker workpieces (160mm vs 140mm) at a faster cutting speed (0.4m / min vs 0.3m / min).

[0123] The processing head provided by this invention is not only suitable for conventional single-focus laser cutting, but also highly suitable for multi-focus laser cutting, especially flame-assisted multi-focus laser cutting. In flame-assisted multi-focus laser cutting, the laser beam has a greater depth of focus, a smaller divergence angle, and a smaller spot diameter within the depth of focus range (0.5mm–1.5mm). This allows the laser beam to maintain a high energy density over a large range (10mm–200mm) along the workpiece thickness direction during cutting, ensuring that the laser beam's focus can penetrate a considerable distance below the workpiece surface (negative defocus), thus achieving higher laser cutting efficiency and kerf quality. This invention utilizes a multi-focus laser beam with a large depth of focus (30mm–80mm) and a small spot diameter (0.5mm–1.5mm), combined with high-pressure oxygen acceleration from a cutting nozzle, to cut thicker metal materials using a lower-power laser (less than 2kW), thereby significantly improving cutting efficiency, kerf quality, and reducing cutting costs. Meanwhile, because the focused spot diameter of the laser beam is sufficiently small (0.5mm~1.5mm) and the focal depth is sufficiently long (30mm~80mm), even using a smaller diameter nozzle allows the multifocal laser beam to pass through the cutting nozzle without energy loss, and ensures that the focal point of the multifocal laser beam can penetrate deep into the workpiece, achieving negative defocus cutting. Furthermore, multifocal beams with a greater focal depth have a wider focus adjustment range, allowing the laser beam's focus to be adjusted to different positions above, on the surface, or inside the workpiece according to different cutting process requirements, thus meeting the cutting needs of different thicknesses and types of metal materials.

[0124] This invention not only overcomes the limitations of traditional laser cutting technology in cutting medium and thick metal materials, such as high equipment cost and low cutting efficiency, but also overcomes the technical bottleneck of poor quality in flame-assisted laser cutting technology when cutting thin metal materials. It can meet the needs of high-quality cutting of metal materials of different thicknesses without requiring high-power laser output.

[0125] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modular laser cutting head with replaceable cutting nozzles, characterized in that, It includes a laser cutting head body (11), a laser beam focusing unit (12), an optical system unit (13), a connecting unit (18), and a cutting nozzle unit (14), wherein: The optical system unit (13), the connecting unit (18), and the cutting nozzle unit (14) are arranged sequentially from top to bottom. The optical system unit (13) is located inside the laser cutting head body (11) and is replaceable. It is used to transform the externally input laser beam and guide it to the connecting unit (18). The optical system unit (13) includes a collimating lens assembly (16) and a focusing lens assembly (17) arranged vertically, and the collimating lens assembly (16) and the focusing lens assembly (17) are inserted into the laser cutting head body (11). The focusing lens assembly (17) includes a multifocal focusing lens, which is a single plano-convex lens with one side being a plane and the other side being a convex curved surface. The convex curved surface is composed of multiple focal curved surfaces with different curvatures, and the curvature of each focal curved surface gradually increases from the center of the multifocal focusing lens outwards. Adjacent focal curved surfaces are transitioned by transition surfaces. The surface equations of each surface in the monolithic plano-convex lens Determine using the following formula: in, Let be the refractive index of a single plano-convex lens. Let i be the focal length corresponding to surface i. Let be the distance from the edge of surface i to the optical axis of the monolithic plano-convex lens. The thickness at the center of a single plano-convex lens. The surface located at the center of the monolithic plano-convex lens is the focal surface, defined as the first surface, and the surface located at the outermost edge of the monolithic plano-convex lens is defined as the second surface. The surface is curved, and N is the number of focal points of a single plano-convex lens, where N≥2; The focal length of the transition surface Determine using the following formula: in, Let k be the focal length of the transition surface. , Let k-1 and k+1 be the focal lengths of the focal surfaces, respectively. , These are the distances from the edges of the focal surfaces k-1 and k+1 to the optical axis of the monolithic plano-convex lens, respectively. This is the distance from the edge of the transition surface to the optical axis of the monolithic plano-convex lens. , ; The laser beam focusing unit (12) is mounted on the laser cutting head body (11) and located beside the optical system unit (13). It is connected to the collimating lens assembly (16) in the optical system unit (13) and is used to adjust the focal position of the laser beam emitted from the optical system unit (13). The connecting unit (18) is connected to the lower end of the laser cutting head body (11) and is located directly below the optical system unit (13) for guiding the laser beam to the cutting nozzle unit (14). The cutting nozzle unit (14) is detachably installed at the lower end of the connecting unit (18) to guide the laser beam and cutting gas to the surface of the workpiece to be cut, so as to achieve the cutting of the workpiece; based on the replaceable features of the optical system unit (13) and the cutting nozzle unit (14), the laser cutting head can switch between flame-assisted laser cutting and laser cutting modes, thereby making a set of laser cutting heads suitable for cutting metal materials of various thicknesses.

2. The modular laser cutting head with replaceable cutting nozzles as described in claim 1, characterized in that, The cutting nozzle unit (14) includes a mounting base, a cutting nozzle (14-3) and a height sensing component. The mounting base has a cutting gas channel (14-13). The cutting nozzle (14-3) is detachably mounted on the mounting base and has a laser channel (14-11). The laser channel (14-11) is connected to the cutting gas channel (14-13) on the mounting base.

3. The modular laser cutting head with replaceable cutting nozzles as described in claim 2, characterized in that, The height sensing component is a capacitive height adjustment component, an arc voltage height adjustment component, or a mechanical height adjustment component.

4. The modular laser cutting head with replaceable cutting nozzles as described in claim 3, characterized in that, The height sensing component is a capacitive height adjustment component, including a ceramic ring (14-6), a sensing nozzle (14-7), a spring probe (14-8), and a connector (14-9). The ceramic ring (14-6) is detachably mounted on the bottom of the mounting base and surrounds the cutting nozzle (14-3). The sensing nozzle (14-7) is mounted on the bottom of the ceramic ring (14-6) and surrounds the cutting nozzle (14-3). The connector (14-9) is mounted on the mounting base and is electrically connected to the spring probe (14-8) and an external controller. The spring probe (14-8) is connected to the upper end of the ceramic ring (14-6), and the lower end of the ceramic ring (14-6) contacts the sensing nozzle (14-7). The spring probe (14-8) is electrically connected to the sensing nozzle (14-7).

5. The modular laser cutting head with replaceable cutting nozzles as described in claim 2, characterized in that, The mounting base is also provided with a combustion gas channel (14-10) and a combustion-supporting gas channel (14-12). The combustion gas channel (14-10) is used to deliver combustion gas to the cutting nozzle (14-3), and the combustion-supporting gas channel (14-12) is used to deliver combustion-supporting gas to the cutting nozzle (14-3).

6. The modular laser cutting head with replaceable cutting nozzles as described in claim 2, characterized in that, The cutting nozzle (14-3) is a flame-assisted laser cutting nozzle or a laser cutting nozzle. The flame-assisted laser cutting nozzle includes a nozzle body (19-1). The nozzle body (19-1) has a laser channel one (14-11) in the middle and a mixed gas channel (19-2) on the side. The laser channel one (14-11) is used for the passage of the laser beam and the cutting gas, and the mixed gas channel (19-2) is used for the passage of the combustion gas and the combustion-supporting gas. The lower end of the laser channel one (14-11) is designed as a Laval structure. The laser cutting nozzle includes a laser cutting nozzle body. The laser cutting nozzle body has a laser channel two (14-16) in the middle for the passage of the laser beam and the cutting gas; or the laser cutting nozzle body has a laser channel two (14-16) in the middle and a cutting gas channel two (14-17) on the side, wherein the laser channel two (14-16) is used for the passage of the laser beam and the cutting gas channel two (14-17) is used for the passage of the cutting gas.

7. The modular laser cutting head with replaceable cutting nozzles as described in claim 6, characterized in that, The flame-assisted laser cutting nozzle also includes a gas mixing unit, which is connected to the combustion gas passage (14-10) and / or the combustion-supporting gas passage (14-12) on the mounting base.

8. The modular laser cutting head with replaceable cutting nozzles as described in claim 7, characterized in that, The gas mixing unit includes a gas mixing structure (14-14) and an air intake structure (14-15) connected to each other. The air intake structure (14-15) is used to send combustion gas and combustion-supporting gas into the gas mixing structure (14-14) through different inlets. The gas mixing structure (14-14) is used to mix the combustion gas and combustion-supporting gas and then send the mixture into the mixed gas channel (19-2) through the combustion gas channel (14-10) and / or combustion-supporting gas channel (14-12) on the mounting base.

9. The modular laser cutting head with replaceable cutting nozzles as described in claim 8, characterized in that, The air intake structure (14-15) is an injection-type structure, which includes two inlets, one for inputting combustion-supporting gas and the other for inputting combustion gas.

10. The modular laser cutting head with replaceable cutting nozzles as described in claim 1, characterized in that, Protective lens assemblies (15) are provided above the collimating lens assembly (16) and below the focusing lens assembly (17).

11. The modular laser cutting head with replaceable cutting nozzles as described in claim 10, characterized in that, The laser cutting head body (11) has multiple horizontal mounting slots from top to bottom, and the collimating lens assembly (16), focusing lens assembly (17) and protective lens assembly (15) are arranged in the corresponding horizontal mounting slots in an insert manner.

12. The modular laser cutting head with replaceable cutting nozzles as described in claim 10, characterized in that, The collimating lens assembly (16) includes a collimating lens mount (16-2) and a collimating lens (16-3). The collimating lens mount (16-2) has a lens mounting slot. The collimating lens (16-3) is installed in the lens mounting slot of the collimating lens mount (16-2) for collimating the laser beam. The collimating lens mount (16-2) is also connected to a lens mount connector (16-5). The collimating lens mount (16-2) is connected to the laser beam focusing unit (12) through the lens mount connector (16-5).

13. The modular laser cutting head with replaceable cutting nozzles as described in claim 10, characterized in that, The focusing lens assembly (17) further includes a focusing lens mount (17-7), a mount connecting plate (17-2), and a flexible mounting member (17-4). The multifocal focusing lens is fixed within the focusing lens mount (17-7). A mounting groove is provided circumferentially on the outer side of the focusing lens mount (17-7). The flexible mounting member (17-4) is arranged circumferentially around the outer side of the focusing lens mount (17-7) and is embedded in the mounting groove. Both ends of the flexible mounting member (17-4) are fixed to the mount connecting plate (17-2). The focusing lens mount (17-7) faces the multifocal focusing lens. A positioning plate (17-3) is provided on one side of the lens mount connecting plate (17-2); the lens mount connecting plate (17-2) is detachably connected to the laser cutting head body (11), and a positioning groove that cooperates with the positioning plate (17-3) is provided on it. An adjusting rod (17-1) is also installed on the lens mount connecting plate (17-2). One end of the adjusting rod (17-1) abuts against the outer side of the focusing lens mount (17-7). The relative position of the focusing lens mount (17-7) and the lens mount connecting plate (17-2) is adjusted by the movement of the adjusting rod (17-1).

14. The modular laser cutting head with replaceable cutting nozzles as described in claim 10, characterized in that, The protective lens assembly (15) includes a protective lens base (15-2) and a protective lens (15-4). The protective lens (15-4) is mounted on the protective lens base (15-2) by a fixing assembly. The protective lens base (15-2) is connected to a protective lens connecting plate (15-1). The protective lens connecting plate (15-1) is detachably connected to the laser cutting head body (11).

15. The modular laser cutting head with replaceable cutting nozzles as described in claim 12, characterized in that, The laser beam focusing unit (12) includes a motor (12-12), a lead screw (12-6), a guide rail (12-3), and a guide rail slider (12-4). The motor (12-12) is mounted on the laser cutting head body (11) and connected to the lead screw (12-6) to drive the lead screw (12-6) to rotate. The lead screw (12-6) is threadedly engaged with the lens mount connector (16-5). The guide rail (12-3) is mounted on the laser cutting head body (11) and slidably engaged with the guide rail slider (12-4). The guide rail slider (12-4) is connected to the lens mount connector (16-5) through the guide rail connecting plate (12-5).

Images