WO2024125671A1

WO2024125671A1 - Combined laser cutting machining head with replaceable cutting nozzle

Info

Publication number: WO2024125671A1
Application number: PCT/CN2024/075026
Authority: WO
Inventors: 曾晓雁; 徐高风; 王海斌; 罗瑞峰; 谢文昌; 郑清明; 胡锦; 奚海
Original assignee: 江苏乐希激光装备有限公司; 江苏乐希激光科技有限公司
Priority date: 2022-12-14
Filing date: 2024-01-31
Publication date: 2024-06-20
Also published as: CN117283149A

Abstract

In the technical field of metal thermal cutting, a combined laser cutting machining head with a replaceable cutting nozzle. The combined laser cutting machining head comprises 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 laser beam focusing unit (12) is mounted on the laser cutting head body (11), the remaining three units are sequentially arranged from top to bottom, the optical system unit (13) is arranged in the laser cutting head body (11), the connecting unit (18) is connected to a lower end of the laser cutting head body (11) and is located right below the optical system unit (13), and the cutting nozzle unit (14) is detachably mounted at a lower end of the connecting unit (18). The present application not only breaks through the limitations of the high apparatus cost and low cutting efficiency of traditional laser cutting processes in the field of the cutting of medium-thickness and large-thickness metal materials, but also overcomes the technical bottleneck of the poor quality of a flame-assisted laser cutting process when cutting thin metal materials; thus, the present application can satisfy the requirements of the high-quality cutting of metal materials with different thicknesses without requiring a laser output with an extremely high power.

Description

Combined laser cutting processing head with replaceable cutting nozzle

[Technical field]

The present application belongs to the technical field of metal thermal cutting, and more specifically, relates to a combined laser cutting processing head with a replaceable cutting nozzle.

【Background technique】

As an emerging metal thermal cutting technology, laser cutting technology has been widely used in the fields of machinery manufacturing, automobiles, and aerospace with its unique principle. In the field of thin sheet metal material cutting, laser cutting technology can cut thin sheet metal materials at an extremely fast cutting speed by using its high energy density laser beam as a heat source, and has good cutting quality, small slit width, high cutting accuracy, and small heat-affected zone. Therefore, it has an absolute advantage in cutting thin sheet metal materials and even medium-thickness (about 20mm) metal materials. However, when the thickness of the metal material is greater than 30mm, not only is the laser power required for laser cutting very high, but the laser cutting efficiency and cutting quality also drop sharply, resulting in a substantial increase in the cost of the cutting equipment. In particular, the increase in the cutting speed of thick metal materials by simply increasing the laser power is also very limited. In short, laser cutting technology no longer has an advantage over traditional cutting technologies such as flame cutting and plasma cutting in the field of cutting thick metal materials.

On the other hand, traditional flame cutting technology has been one of the main cutting methods for thick metal materials due to its advantages such as good thick plate metal material cutting ability and low equipment cost. However, flame cutting technology also has many shortcomings, such as long preheating time before cutting, low cutting efficiency, difficulty in perforating, etc., which limits its application in many applications, making thick plate cutting often have to rely on mechanical processing technologies such as milling. Therefore, flame-assisted laser cutting technology has been proposed in this field to combine the advantages of high laser cutting accuracy, fast speed and good cutting quality with the advantages of flame cutting thick metal materials. By using high-temperature flame to preheat the workpiece, the laser power required for laser cutting can be greatly reduced, so that only a lower-power laser can be used to cut thicker workpieces. Therefore, it has important industrial application value.

Although the cutting efficiency and slit quality of flame-assisted laser cutting thick metal materials are significantly better than those of traditional laser cutting technology or flame cutting technology, the flame-assisted laser cutting introduces a combustion flame, resulting in a relatively wide slit and a large heat-affected zone, so it is only advantageous when cutting thick plates. If the same cutting method is used to cut thin metal materials, it is difficult to achieve the desired effect. In other words, although the flame-assisted laser cutting processing head can cut thick metal materials, it has no advantages in cutting speed and slit quality when used to cut thin metal materials. The traditional laser cutting processing head can cut thin metal materials with high quality and high efficiency, but has great limitations when cutting thick metal materials. Therefore, if the cutting advantages of traditional laser cutting technology in thin metal materials and the cutting advantages of flame-assisted laser cutting technology in thick metal materials can be combined, so that a laser cutting equipment and a laser cutting head can not only cut thick metal materials with high efficiency and high quality, but also cut thin metal materials with high efficiency and high precision, then it will undoubtedly greatly improve the process adaptability and equipment utilization of laser cutting equipment, which will have great benefits for industry. It has important engineering application value in the field, and the key is to develop a "universal" laser cutting processing head that can achieve high-efficiency and high-quality cutting of thick/thin plate metal materials.

[Summary of the invention]

In response to the various defects or improvement needs of existing laser cutting technology, the present application provides a combined laser cutting processing head with a replaceable cutting nozzle, which can meet the needs of high-quality cutting of metal materials of different thicknesses, breaking through the limitations of traditional laser cutting technology in the field of cutting thick metal materials, such as high equipment cost and low cutting efficiency, and the technical bottleneck of flame-assisted laser cutting technology in cutting thin plate metal materials, such as poor quality and low processing efficiency.

To achieve the above-mentioned purpose, the present application proposes a combined laser cutting processing head with a replaceable cutting nozzle, which includes a laser cutting head body, a laser beam focusing unit, an optical system unit, a connecting unit and a cutting nozzle unit, wherein the laser beam focusing unit is installed on the laser cutting head body, and is used to adjust the focal position of the laser beam emitted by the optical system unit; the optical system unit, the connecting unit and the cutting nozzle unit are arranged in sequence from top to bottom, wherein the optical system unit is arranged in the laser cutting head body and is replaceable, and is used to perform beam transformation on the external 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, and is used to guide the laser beam to the cutting nozzle unit, and the cutting nozzle unit is detachably installed at the lower end of the connecting unit, and is used to guide the laser beam and cutting gas to the workpiece to be cut, so as to achieve cutting of the workpiece to be cut.

As a further preferred embodiment, the cutting nozzle unit includes a mounting seat, a cutting nozzle and a height sensing component, the mounting seat is provided with a cutting gas channel, the cutting nozzle is detachably mounted on the mounting seat, and is provided with a laser channel, which is communicated with the cutting gas channel on the mounting seat.

As a further preference, the height sensing component is a capacitive height adjustment component, an arc voltage height adjustment component or a mechanical height adjustment component.

As a further preferred embodiment, the height sensing component is preferably a capacitive height adjustment component, including a ceramic ring, a sensing nozzle, a spring probe and a connecting piece. The ceramic ring is detachably mounted on the bottom of the mounting seat and is arranged around the cutting nozzle. The sensing nozzle is mounted on the bottom of the ceramic ring and is arranged around the cutting nozzle. The connecting piece is mounted on the mounting seat 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, the lower end of the ceramic ring is in contact with the sensing nozzle, and the spring probe is electrically connected to the sensing nozzle.

As a further preference, a combustion gas channel and a combustion-supporting gas channel are also provided on the mounting seat, 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.

As further preferred, the cutting nozzle is a flame-assisted laser cutting nozzle or a laser cutting nozzle, the flame-assisted laser cutting nozzle comprises a nozzle body, a laser channel is provided in the middle of the nozzle body, and a mixed gas channel is provided on the side, the laser channel is used for passing the laser beam and the cutting gas, the mixed gas channel is used for passing the combustion gas and the combustion-supporting gas, and the lower end of the laser channel is designed as a Laval structure; the laser cutting nozzle comprises a laser cutting nozzle body The laser cutting nozzle body has a laser channel in the middle for passing 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 used for passing the laser beam and the cutting gas channel is used for passing the cutting gas.

As a further preference, the flame-assisted laser cutting nozzle further comprises a gas mixing unit, which is in communication with the combustion gas channel and/or the combustion-supporting gas channel on the mounting seat.

As a further preference, the gas mixing unit comprises a gas mixing structure and an air intake structure which are connected to each other, the air intake structure being used to deliver the combustion gas and the combustion-supporting gas into the gas mixing structure through different inlets, and the gas mixing structure being used to mix the combustion gas and the combustion-supporting gas and deliver them into the mixed gas channel through the combustion gas channel and/or the combustion-supporting gas channel on the mounting base.

As a further preference, the air intake structure is an injection-suction structure, which includes two input ports, one of which is used to input the combustion-supporting gas, and the other is used to input the combustion gas.

As further preferred, the optical system unit comprises a collimating lens assembly and a focusing lens assembly which are arranged vertically, and a protective lens assembly is provided above the collimating lens assembly and below the focusing lens assembly.

As a further preference, the laser cutting head body is provided with a plurality of horizontal installation grooves from top to bottom, and the collimating lens assembly, focusing lens assembly and protective lens assembly are integrally arranged in the corresponding horizontal installation grooves in a plug-in manner.

As a further preferred embodiment, the collimating lens assembly includes a collimating lens seat and a collimating lens, the collimating lens seat is provided with a lens mounting groove, and the collimating lens is installed in the lens mounting groove of the collimating lens seat for collimating the laser beam; the collimating lens seat is also connected to a lens seat connector, and the collimating lens seat is connected to the laser beam focusing unit via the lens seat connector.

As a further preferred embodiment, the focusing mirror assembly includes a focusing mirror, a focusing mirror seat, a lens seat connecting plate and an elastic mounting piece, wherein the focusing mirror is fixed in the focusing mirror seat; a mounting groove is provided in the outer circumference of the focusing mirror seat, the elastic mounting piece is arranged around the outer circumference of the focusing mirror seat and is embedded in the mounting groove, and both ends of the elastic mounting piece are fixed to the lens seat connecting plate, and a positioning plate is provided on the side of the focusing mirror seat facing the lens seat connecting plate; the lens seat connecting plate is detachably connected to the laser cutting head body, and a positioning groove is provided on the lens seat connecting plate to cooperate with the positioning plate, and an adjusting rod is also installed on the lens seat connecting plate, one end of the adjusting rod abuts against the outer side surface of the focusing mirror seat, and the relative position of the focusing mirror seat and the lens seat connecting plate is adjusted by the action of the adjusting rod.

As a further preference, the focusing lens is a multi-focal focusing lens, preferably, the multi-focal focusing lens is a single lens, a combined lens, a diffractive lens, a reflective lens or a metal lens; preferably, the multi-focal focusing lens is a single plano-convex lens, one side of which is a flat surface, and the other side is a convex surface, the convex surface is composed of a plurality of focal surfaces with different curvatures, and the curvature of each focal surface gradually increases from the center of the multi-focal focusing lens to the outside, and two adjacent focal surfaces are transitioned by a transition surface.

As further preferred, the protective mirror assembly includes a protective mirror seat and a protective mirror, the protective mirror is mounted on the protective mirror seat via a fixing assembly, the protective mirror seat is connected to a protective mirror connecting plate, and the protective mirror connecting plate is detachably connected to the laser cutting head body.

As a further preferred embodiment, the laser beam focusing unit includes a motor, a screw, a guide rail and a guide rail slider. The motor is installed on the laser cutting head body and is connected to the screw for driving the screw to rotate. The screw is threadedly engaged with the mirror seat connector. The guide rail is installed on the laser cutting head body and slidably engaged with the guide rail slider. The guide rail slider is connected to the mirror seat connector via a guide rail connecting plate.

In general, the above technical solutions conceived by this application have the following technical advantages compared with the prior art:

1. The combined laser cutting processing head with replaceable nozzles provided in this application can replace the cutting nozzle unit according to the thickness of the workpiece to be cut. When cutting thin metal materials, the traditional laser cutting mode is used; when cutting thick metal materials, the flame-assisted laser cutting mode is used, so that a cutting processing head can cut metal materials of all thicknesses, and the power of the laser used does not need to be very high. When cutting metal materials of different thicknesses, this application can switch between different cutting modes by replacing the cutting nozzle unit at the bottom of the cutting head or replacing the cutting nozzle in the cutting nozzle unit. It has the characteristics of simple operation and strong practicality. It can effectively combine and fully utilize the characteristics of fast cutting speed, good cutting quality, small slit width and small heat-affected zone of traditional laser cutting of thin metal materials and the advantages of large cutting thickness, high efficiency, low equipment cost and good cutting quality when cutting thick metal materials with flame-assisted laser cutting, so as to achieve low-cost and high-efficiency cutting of metal materials of full thickness.

2. The combined laser cutting processing head provided in the present application has dynamic focusing function and height sensing function. On the one hand, through the structural design of the laser beam focusing unit, the focus of the laser beam can be intelligently adjusted to adapt to different perforation and cutting processes; on the other hand, through the structural design of the cutting nozzle unit, real-time monitoring of the distance from the nozzle to the surface of the workpiece to be cut can be achieved, and then during cutting, the height of the entire cutting head can be adjusted through an external controller according to the height sensing signal, so that the focus of the laser beam is always located at the same position of the workpiece to be cut during the cutting process, thereby ensuring the stability and reliability of the cutting quality.

3. When the cutting processing head of the present application uses the flame-assisted laser cutting mode to cut thick metal materials, the focal depth of the laser beam can be increased by replacing the focusing mirror of the cutting head, so that the focus 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 make its flow rate reach a supersonic state, thereby ensuring that the oxygen concentration and flow rate at the bottom of the cut are maintained at a high level, making the oxygen-iron reaction more complete, releasing more heat energy, and blowing away the slag better, thereby obtaining better cut quality and processing efficiency.

4. The cutting processing head provided in this application has a flame-assisted laser cutting function, and is equipped with a supersonic Laval structure cutting nozzle, so that it can use a relatively low power (1kW~8kW) laser to cut full thickness (1mm-200mm) metal materials, effectively avoiding the high-power laser (10kw, 20kw or even higher) required for cutting thick metal materials (thickness greater than 30mm) in traditional laser cutting processes, and the low cutting efficiency. The problem, while ensuring cutting efficiency and cutting quality, greatly reduces the equipment cost investment.

5. The processing head of the present application can be applied to flame-assisted multi-focus laser cutting, and can obtain a more The laser beam with high power density and smaller divergence angle can not only achieve positive defocus cutting but also negative defocus cutting during laser cutting, thereby making the laser beam energy density at the bottom of the workpiece higher. Compared with single-focus flame-assisted laser cutting, it has more 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 existing technology that requires more than 6 kilowatts or even tens of thousands of watts of laser power, this application will greatly reduce the laser power without affecting the cutting efficiency and quality, achieving a qualitative breakthrough in this field.

【Brief Description of the Drawings】

FIG1 is a perspective view of a combined laser cutting processing head with a replaceable cutting nozzle provided in an embodiment of the present application;

FIG2 is a front view of a combined laser cutting processing head with a replaceable cutting nozzle provided in an embodiment of the present application;

Fig. 3 is a cross-sectional view taken along line A-A of Fig. 2;

FIG4 is a schematic structural diagram of a laser cutting head body provided in an embodiment of the present application;

FIG5 is a schematic structural diagram of a protective mirror assembly provided in an embodiment of the present application;

Fig. 6 is a cross-sectional view taken along line A-A of Fig. 5;

FIG7 is a schematic structural diagram of a collimating lens assembly provided in an embodiment of the present application;

Fig. 8 is a cross-sectional view taken along line B-B of Fig. 7;

FIG9 is a schematic diagram of the structure of a focusing mirror assembly provided in an embodiment of the present application;

Fig. 10 is a cross-sectional view taken along line A-A of Fig. 9;

FIG11 is a schematic structural diagram of a laser beam focusing unit provided in an embodiment of the present application;

Fig. 12 is a cross-sectional view taken along line A-A of Fig. 11;

FIG13 is a schematic structural diagram of a cutting nozzle unit provided in an embodiment of the present application;

Fig. 14 is a cross-sectional view taken along line B-B of Fig. 13;

FIG15 is a schematic diagram of the structure of a mounting base provided in an embodiment of the present application;

FIG16 is a schematic diagram of the structure of a flame-assisted laser cutting nozzle provided in an embodiment of the present application;

FIG. 17 is a schematic diagram of the structure of a flame-assisted laser cutting nozzle gas mixing unit provided in an embodiment of the present application.

FIG18 is a schematic diagram of the structure of a laser cutting nozzle provided in an embodiment of the present application;

FIG19 is a schematic diagram of the structure of a plano-convex dual-focus focusing lens provided in an embodiment of the present application;

Figure 20 is a side view of the plano-convex dual-focal point focusing lens provided in an embodiment of the present application.

Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:
1 optical fiber connector; 2 aviation plug; 3 main cooling water channel; 7 cooling water channel; 8 protective mirror 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 screw rod, 12-7 rear bearing seat, 12-8 rear bearing, 12-9 bearing locking nut, 12-10 coupling, 12-11 motor seat, 12-12 motor; 13 optical system unit; 14 cutting nozzle unit, 14-1 upper seat body, 14-2 lower seat, 14-3 cutting nozzle, 14-4 nozzle locking nut, 14-5 nut, 14-6 ceramic ring, 14-7 induction nozzle, 14-8 spring probe, 14-9 connector, 14-10 combustion gas channel, 14-11 laser channel 1, 14-12 combustion-supporting gas channel, 14-13 cutting gas channel 1, 14-14 mixing structure, 14-15 intake structure, 14-16 laser channel 2, 14-17 cutting gas channel 2; 15 protective mirror assembly, 15-1 protective mirror connecting plate, 15 -2 protective mirror seat, 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 seat, 16-3 collimating mirror, 16-4 clamping nut, 16-5 mirror seat connector; 17 focusing mirror assembly, 17-1 adjusting rod, 17-2 mirror seat connecting plate, 17-3 positioning plate, 17-4 elastic mounting part, 17-5 focusing mirror, 17-6 clamping nut, 17-7 focusing mirror seat; 18 lower connecting seat; 19-1 nozzle body, 19-2 mixed gas channel.

【Detailed ways】

In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

As shown in Figures 1-3, the embodiment of the present application provides a combined laser cutting processing head with a replaceable cutting nozzle, which 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 laser beam focusing unit 12 is installed on the laser cutting head body 11, and is used to adjust the focal position of the laser beam; the optical system unit 13, the connecting unit 18 and the cutting nozzle unit 14 are arranged in sequence from top to bottom, wherein the optical system unit 13 is arranged in the laser cutting head body 11, and is used to shape, transform, and adjust the laser beam input from the outside. Focusing, and guiding the focused laser beam to the connection unit 18, the connection 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, and is used to guide the laser beam to the cutting nozzle unit 14, and the cutting nozzle unit 14 is detachably installed at the lower end of the connection unit 18, and is used to guide the laser beam and cutting gas, combustion gas and combustion-supporting gas to the surface of the workpiece to be cut, so as to achieve cutting of the workpiece to be cut. The combined laser cutting processing head with replaceable nozzles provided in this application is particularly suitable for cutting carbon steel materials of various thicknesses.

As shown in FIG4 , the laser cutting head body 11 is a frame structure, which serves as the installation base of the entire cutting processing head and integrates and connects other functional units. As shown in FIG3 , the optical system unit 13 is located in the middle position inside 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 acts on the workpiece to be cut. Specifically, the laser cutting head body 11 is provided with 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 unobstructed in 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 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.

Specifically, as shown in FIG3 , the optical system unit 13 includes a collimator lens assembly 16 and a focusing lens assembly 17 arranged in an upper and lower position, wherein the collimator 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 shown in FIG7 and FIG8 , the collimator lens assembly 16 includes a collimator lens seat 16-2 and a collimator lens 16-3, wherein the collimator lens seat 16-2 is provided with a lens mounting groove, and the collimator lens 16-3 is installed in the lens mounting groove of the collimator lens seat 16-2 through a clamping nut 16-4, and is used to collimate the laser beam, expand the laser beam with a certain divergence angle, and transform it into a parallel beam. The collimator lens seat 16-2 is also connected to a lens seat connector 16-5, and the collimator lens seat 16-2 is connected to the laser beam focusing unit 12 through the lens seat connector 16-5. Specifically, a dynamic focusing scale 16 - 1 is also provided on the collimator lens holder 16 - 2 , which is used to observe the moving distance of the collimator lens holder 16 - 2 during the dynamic focusing process and calculate the position of the laser beam focus.

As shown in FIG3 , the focusing lens assembly 17 is arranged below the collimating lens assembly 16 , preferably 30 mm to 200 mm below the collimating lens assembly 16 , that is, the spacing between the focusing lens seat 17-7 and the collimating lens seat 16-2 is 30 mm to 200 mm. The above parameters can reduce the size of the cutting head under the premise of ensuring the installation space of the focusing lens. As shown in FIG9 and FIG10 , the focusing lens assembly 17 includes a focusing lens 17-5, a focusing lens seat 17-7, a lens seat connecting plate 17-2 and an elastic mounting member 17-4. The focusing lens 17-5 is installed in the focusing lens seat 17-7 through a clamping nut 17-6; an installation groove is provided on the outer circumference of the focusing lens seat 17-7, and the elastic mounting member 17-4 is arranged around the outer circumference of the focusing lens seat 17-7 and embedded in the installation groove. The two ends of the elastic mounting member 17-4 are fixed on the lens seat connecting plate 17-2 to clamp the entire focusing lens seat 17-7. A positioning plate 17-3 is also provided on the side of the focusing lens seat 17-7 facing the lens seat connecting plate 17-2, and a positioning groove that cooperates with the positioning plate 17-3 is provided on the lens seat connecting plate 17-2. Accurate positioning between the focusing lens seat 17-7 and the lens seat connecting plate 17-2 is achieved through the cooperation between the positioning plate and the positioning groove. In addition, an adjustment rod 17-1 is also installed on the lens seat connecting plate 17-2, and the lower end of the adjustment rod 17-1 abuts against the outer side surface of the focusing lens seat 17-7, so that the focusing lens can be adjusted by the up and down movement of the adjustment rod 17-1. The distance and angle between the base 17-7 and the lens base connecting plate 17-2 can be adjusted. The lens base connecting plate 17-2 is detachably connected to the laser cutting head body 11. For example, the lens base 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, and by removing the bolts, the focusing lens assembly 17 can be removed as a whole, which is convenient for replacing the lens.

Specifically, the elastic mounting member 17-4 is preferably a spring, and the elastic force of the spring is used to clamp the focusing lens seat 17-7. When the adjusting rod retreats, the elasticity of the spring can be used to return the focusing lens seat 17-7 to its original position. The adjusting rod 17-1 can be a hexagon socket bolt. By rotating the hexagon socket bolt, the length of the hexagon socket bolt extending out of the lens seat connecting plate 17-2 can be adjusted, thereby adjusting the distance and angle between the focusing lens seat 17-7 and the lens seat connecting plate 17-2, thereby adjusting the position of the focusing lens 17-5, thereby achieving the adjustment of the concentricity of the focusing lens 17-5 and the collimating lens 16-3. In order to ensure assembly reliability, two elastic mounting members 17-4 are provided. In order to adjust the focusing lens seat 17-7 within the entire installation plane, two adjusting rods 17-1 are provided, which are arranged on both sides of the positioning plate 17-3, and each adjusting rod 17-1 can be adjusted independently.

As shown in FIG3 , a protective mirror assembly 15 is provided above the collimating mirror assembly 16 and below the focusing mirror assembly 17, which is used to prevent dust from entering the beam transmission channel and damaging optical components when plugging and unplugging optical fibers and the cutting head is working. The protective mirror assembly 15 is located in the laser beam transmission channel of the laser cutting head body 11. As shown in FIG5 and FIG6 , the protective mirror assembly 15 includes a protective mirror seat 15-2 and a protective mirror 15-4. The protective mirror 15-4 is mounted on the protective mirror seat 15-2 through a fixing assembly. The protective mirror seat 15-2 is connected to a protective mirror connecting plate 15-1. The protective mirror connecting plate 15-1 is detachably connected to the laser cutting head body 11. For example, the protective mirror connecting plate 15-1 is fixed to the side of the laser cutting head body 11 by bolts, so that the entire protective mirror assembly is installed on the laser cutting head body 11, and by removing the bolts, the protective mirror assembly can be removed as a whole, which is convenient for replacing the lens. Specifically, the fixing assembly includes a protective lens clamping ring 15-3 and a sealing ring 15-5, which are respectively arranged on the upper and lower surfaces of the protective lens 15-4 and assembled in the protective lens seat 15-2. Specifically, a single or multiple protective lens assemblies 15 can be used to protect the lenses in the collimating lens assembly 16 and the focusing lens assembly 17. In the present application, two protective lens assemblies 15 are respectively used to set double-layer protection for the collimating lens assembly 16 and the focusing lens assembly 17.

Furthermore, the laser beam is provided by a laser. In the present application, a laser that can output a small divergence angle is preferably used. The divergence half angle of the laser beam is 2 ^° to 8 ^° , and the collimator 16-3 and the focusing lens 17-5 are preferably short focal length lenses. By combining a small divergence angle laser beam with a shorter focal length collimator and focusing lens, the spot diameter of the laser beam is made smaller while ensuring that the focal depth is large enough, thereby making it possible for the focus of the laser beam to act below the surface of the workpiece to be cut (i.e., negative defocus, the focus is located inside the workpiece to be cut), thereby greatly increasing the power density of the laser beam entering the slit, making the molten liquid metal in the slit have a higher temperature, a lower viscosity, and is easier to be blown away by high-pressure gas, thereby obtaining better cutting quality and processing efficiency.

Specifically, the laser can be a fiber laser, a disc laser, a diode-pumped solid laser, a high-power gas laser or a semiconductor laser, etc., preferably a fiber laser. Preferably, the fiber core diameter of the fiber laser is 1 μm to 100 μm, preferably 10 μm to 50 μm, the power of the fiber laser is 1 kW to 100 kW, preferably 2 kW to 20 kW, and the power of the fiber laser is 1 kW to 100 kW, preferably 2 kW to 20 kW. Small core diameter lasers are beneficial for reducing the divergence angle of the laser beam, thereby obtaining a laser beam with a larger focal depth. Through the fiber laser with the above parameters, a laser beam with a divergence half angle of 2 ^° to 8 ^° can be obtained.

Furthermore, the diameter of the collimator 16-3 is not greater than 60mm, and the focal length is not greater than 200mm; the diameter of the focusing lens 17-5 is not greater than 60mm, and the focal length is not greater than 600mm. Further preferably, the diameter of the collimator 16-3 is 25mm to 60mm, and the focal length is 50mm to 200mm, and its focal length corresponds to the distance from the collimator seat 16-2 to the optical fiber connector 1 of 50mm to 200mm; the diameter of the focusing lens 17-5 is 25mm to 60mm, and the focal length is 100mm to 600mm, and its focal length corresponds to the distance from the focusing lens 17-5 to the focal position of the laser beam. The above parameters can make the laser beam pass through the cutting nozzle without energy loss. Furthermore, the diameter of the protective lens 15-4 is 15mm to 60mm, and the distance between the collimator 16-3 and the focusing lens 17-5 is 30mm to 200mm. In the preferred embodiment of the present application, the diameters of the protective mirror 15-4, the collimating mirror 16-3 and the focusing mirror 17-5 are 37 mm, the focal length of the collimating mirror is 100 mm, the distance between the collimating mirror and the focusing mirror is 50 mm, and the focal length of the focusing mirror is 400 mm. The two surfaces of the protective mirror 15-4, the collimating mirror 16-3 and the focusing mirror 17-5 are coated with an anti-reflection film having the same or similar wavelength as the laser beam, which is used to increase the transmittance of the laser beam and prevent the optical components from being reflected and losing the laser beam energy or even damaging the optical components. All the fixed contact surfaces of the mirror seats and the laser cutting head body 11 are provided with sealing rings to prevent dust from entering the laser cutting head body 11 during cutting and contaminating and damaging the optical components.

Furthermore, the optical system unit 13 is replaceable, and the collimator lens, focusing lens, and protective lens in the specific optical system unit 13 are replaceable. More specifically, the collimator lens, focusing lens, and protective lens in the present application can be removed from the lens seat by plugging and unplugging, which is used to check whether the optical system is damaged or contaminated, so as to replace the lens. For example, as shown in FIG4 , a horizontally arranged mounting groove is provided at the corresponding position of the protective lens assembly 15, the collimator lens assembly 16, and the focusing lens assembly 17 installed on the side of the laser cutting head body 11, and the protective lens assembly 15, the collimator lens assembly 16, and the focusing lens assembly 17 can be inserted from the mounting groove as a whole, which is very convenient for replacement. For the protective lens assembly 15 and the focusing lens assembly 17, after the overall insertion, the corresponding lens seat connecting plate is detachably installed on the laser cutting head body 11, and the assembly can be fixed. For the collimator lens assembly 16, after the whole is inserted, the laser beam focusing unit 12 is assembled on the laser cutting head body 11, and the screw rod 12-6 in the laser beam focusing unit 12 is threadedly matched with the lens seat connector 16-5 in the collimator lens assembly 16, so that the installation of the collimator lens assembly 16 can be realized. Specifically, a protective lens cover 8 is also provided on the side of the laser cutting head body 11, and the protective lens cover 8 can cover the installation groove to prevent the lens from being contaminated. An observation window 9 is also provided on the laser cutting head body 11, which is used to observe the distance moved by the collimator lens during the focusing process, so as to calculate the actual moving distance of the laser beam focus.

Preferably, the focusing lens 17-5 is a multi-focal focusing lens, which can be a single lens, a combined lens, or even a diffraction lens, a reflective lens, or a metal lens, etc. Its main function is to transform the collimated parallel light beam into a laser beam with multiple focal points distributed along the optical axis. The present application preferably uses a single-piece plano-convex lens, which has the characteristics of simple structure, easy implementation, and low cost. At the same time, the energy distribution of the multi-focal laser beam generated by the lens is more uniform, making the cutting section smoother, the section verticality better, and the cutting speed faster. The multi-focal focusing lens focuses the vertically incident parallel light beam into a multi-focal laser beam with multiple focal points ( _P1 , _P2 , ..., _PN ) in the direction of the optical axis, and the spacing between each focus is The energy size can be designed according to the needs. According to the thickness of the metal sheet to be cut, the focus of the multi-focus laser beam can be located on the upper part, surface and inside of the workpiece to be cut.

As shown in Figures 19 and 20, the multi-focal focusing mirror is a plano-convex mirror, whose lower surface is a plane and the upper surface is a convex surface. The convex surface is composed of a plurality of focal surfaces with different curvatures, and the curvature of each focal surface gradually increases from the center of the multi-focal focusing mirror to the outside, and the transition between two adjacent focal surfaces is a transition surface. Specifically, the number of focal surfaces is N, and the number of transition surfaces is N-1, where N is the number of focal points of the multi-focal laser beam, and N≥2. That is, the convex surface of the multi-focal focusing mirror is designed to have a plurality of different surfaces along the edge direction from the center of the lens according to the number of focal points, that is, it is composed of 2N-1 different surfaces, including N focal surfaces and N-1 transition surfaces connecting the focal surfaces.

More specifically, taking the center of the plane of the focusing mirror as the origin, assuming that the surface equation is y _i =g( _ri ), where y is the thickness from the convex surface of the focusing mirror to the plane (g(0)=H), the surface equation y _i of each surface (including the focal surface and the transition surface) is determined using the following formula (1):

Wherein, _yi is the surface equation of surface i, n is the refractive index of the multi-focal focusing mirror, _fi is the focal length corresponding to surface i, _ri is the distance from the edge of surface i to the optical axis of the multi-focal focusing mirror (the maximum value is D/2, where D is the diameter of the multi-focal focusing mirror), H is the center thickness of the multi-focal focusing mirror, i=1,2,3,...,2N-1, wherein the surface located at the center of the multi-focal focusing mirror is the focal surface, defined as the first surface, and the surface located at the outermost edge of the multi-focal focusing mirror is defined as the 2N-1 surface, that is, from the center to the outside of the multi-focal focusing mirror are the 1st, 2nd, 3rd,...,2N-1 surfaces, and the 1st, 3rd, 5th,...,2N-1th surfaces are focal surfaces, and the 2nd, 4th, 6th,...,2N-2th surfaces are transition surfaces.

Furthermore, the focal length of the focal surface and the distance from the edge of the focal surface to the optical axis of the multi-focal focusing mirror can be preset according to actual needs. The focal length of the transition surface is determined according to 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 multi-focal focusing mirror using the following formula (2):

Among them, fk _-1 is the focal length of surface k-1 (that is, the focal length corresponding to each focal surface), rk _-1 is the distance from the edge of surface k-1 to the optical axis of the multi-focal focusing mirror (that is, the distance from the edge of each focal surface to the optical axis of the multi-focal focusing mirror), r is the distance from the edge of the transition surface to the optical axis of the multi-focal focusing mirror, r∈[rk _-1 , rk ₊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 multi-focal focusing mirror, k＝2,4,6,...,2N-2.

Substituting n, H and the focal length values corresponding to different surfaces into formula (1), the surface equations of each surface on the convex surface of the multi-focus focusing mirror y _i =g( _ri ) can be calculated. The collimated parallel light beam is transmitted to different surfaces on the convex surface of the focusing mirror. Different surfaces have different f values, and the laser beam is focused to different positions of the optical axis. Among them, the 1st, 3rd, 5th, ..., 2N-1st surfaces are focal surfaces for forming N focal points, and the 2nd, 4th, 6th, ..., 2N-2nd surfaces are transition surfaces. The focal length of the transition surface is between two adjacent focal surfaces. Gradual change within the focal length range. Changing the focal length of the focal surface and the distance from the edge of the focal surface to the optical axis of the multi-focus focusing lens can correspondingly change the relative position of each focus and the energy of the beam at each focus and the focus gradient area.

As shown in FIG19 , a dual-focus focusing lens is provided. The dual-focus focusing lens is a plano-convex lens, and its convex surface has three different curved surfaces S1, S2, and S3 from the center of the lens along the edge direction. The focal lengths of the two focal points (P1 and P2) of the dual-focus focusing lens are 400 mm and 420 mm respectively. Curved surface S1 is the focal curved surface corresponding to the focal length of 420 mm. Curved surface S3 is the focal curved surface corresponding to the focal length of 400 mm. Curved surface S3 is the transition curved surface connecting the two focal curved surfaces. The focusing lens diameter is set to 37 mm, the center thickness is 8 mm, the material refractive index is 1.45, and the radii r ₁ and r ₃ of curved surfaces S1 and S3 are 3 mm and 7 mm respectively. Substituting the above parameters into formula (1) can calculate the equation y ₁ (r) of curved surface S1 and the equation y ₃ (r) of curved surface S3; in addition, substituting the above parameters into formula (2) can calculate the focal length of transition curved surface S2. Among them, 3≤r≤7, and then substituting the focal length of the transition surface S2 into formula (1) to obtain the transition surface S2 equation y ₂ (r), the three surface equations y ₁ (r), y ₂ (r) and y ₃ (r) can be used to model the F400-F420 dual-focus focusing lens, as shown in Figure 2. The lens model is imported into optical simulation software (such as Zemax) for optical simulation. When the lens model meets the actual requirements, it can be processed and manufactured according to the engineering drawing of the output lens model.

Depending on the thickness of the workpiece to be cut, the number and area of curved surfaces with different refractive indices and radii of curvature can be selected to change the spacing between the focuses of the multi-focus laser beam, the number of focuses, and the energy at each focus. In addition, in order for the multi-focus laser beam 1 to have sufficient energy and a suitable distribution state inside the workpiece to be cut, the number of focuses N and the spacing S of the beam should not be too large. When cutting thick metal materials, the focus of the laser beam should be located as much as possible inside the workpiece 7 to be cut, so as to effectively overcome the problem of severe slag caused by insufficient laser beam energy at the bottom of the material when a single-focus laser beam cuts thick metal materials. Furthermore, in order to satisfy the requirement that the multi-focus laser beam passes through the cutting nozzle without energy loss and that the focus of the laser beam is located inside the workpiece to be cut, and at the same time that the energy at each focus of the laser beam is evenly distributed to adapt to the cutting of metal materials of different thicknesses, the focal length of the focus curve located at the center of the multi-focus focusing mirror is 200mm-600mm, preferably 300mm-500mm, the number of focuses is 2-8, preferably 2-4, the spacing between two adjacent focuses is 5mm-50mm, preferably 10mm-40mm, and the light-through area of other focus curves is 1-3 times the light-through area of the focus curve located at the center of the multi-focus focusing mirror. Through the above design and the design of relevant parameters of the collimator, the multi-focus laser beam The focal points partially or completely act below the surface of the workpiece, so that during laser cutting, not only positive defocus cutting but also negative defocus cutting can be achieved, thereby making the laser beam energy density at the bottom of the workpiece higher. Compared with single-focus flame-assisted laser cutting, it has more 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 existing technology that requires more than 6 kilowatts or even tens of thousands of watts of laser power, the present application will greatly reduce the laser power without affecting the cutting efficiency and quality, achieving a qualitative breakthrough in this field.

The processing head of the present application can realize flame-assisted multi-focus laser cutting, and can obtain a laser beam with a larger focal depth and a smaller divergence angle, so that even if the Laval structure of the cutting nozzle is very narrow and long, the laser beam can still pass through the area without loss. At the same time, the narrow and long Laval structure continuously accelerates the cutting gas to ensure that the oxygen concentration and flow rate acting on the cut workpiece area are still maintained at a high level, so that the oxygen-iron reaction is more sufficient, more heat energy is released, the slag is blown away better, and the cutting speed and cutting seam quality are better; and because the spot diameter of the laser beam is smaller, the Laval structure caliber at the bottom of the cutting nozzle can be correspondingly smaller. Under the same circumstances, the consumption of cutting gas is smaller and the cutting cost is lower. The cutting head of the present application can organically combine the multi-focus laser beam and the Laval cutting nozzle, making it possible to cut thicker metal materials with lower laser power, and can cut metal materials of different thicknesses, with a wider range of applications.

As shown in Figures 11 and 12, the laser beam focusing unit 12 includes a motor 12-12, a screw rod 12-6, a guide rail 12-3 and a guide rail slider 12-4, wherein the motor 12-12 is used as a power device of the laser beam focusing unit 12, and is installed on the laser cutting head body 11 through the motor seat 12-11, and is connected to the screw rod 12-6 through the coupling 12-10, and is used to drive the screw rod 12-6 to rotate, and the screw rod 12-6 is threadedly matched with the lens seat connector 16-5 in the collimator lens assembly; the guide rail 12-3 is installed on the laser cutting head body 11, and is slidably matched with the guide rail slider 12-4; the guide rail slider 12-4 is connected to the lens seat connector 16-5 through the guide rail connecting plate 12-5. When the motor 12-12 drives the screw rod 12-6 to move, under the guidance of the guide rail and the guide rail slider, the collimator lens assembly 16 moves up and down, 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 sensor signal to the controller to stop the motor 12-12, thereby controlling the movement stroke of the guide rail slider 12-4 and limiting the focusing range. In this application, the focusing range is set to -20mm~20mm.

In order to ensure the stability of adjustment, a rear bearing 12-8 is installed at one end of the screw rod 12-6 close to the motor 12-12. The rear bearing 12-8 is fixed to the laser cutting head body 11 under the joint 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 screw rod 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 plug 2 is installed on the laser cutting head body 11, and the aviation plug 2 is connected to the motor 12-12 and to an external controller. The start and stop of the motor 12-12 is controlled by an external pulse signal input through the aviation plug 2. The motor 12-12 drives the screw rod 12-6 to move, and at the same time, the collimator lens assembly 16 moves 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 collimator lens assembly 16 only moves up and down. When the spatial position of the collimator lens assembly 16 changes, the optical system unit 13 changes, so that the focal position of the laser beam changes, thereby realizing the adjustment of the focus of the laser beam.

Different focusing modes can be adopted depending on whether the guide rail slider 12-4 is connected to different optical components. When the guide rail slider 12-4 is connected to the collimating lens assembly 16, it is called the collimating focusing mode, and when it is connected to the focusing lens assembly 17, it is called the focusing focusing mode. In this application, the collimating focusing mode is preferably adopted, 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.

As shown in FIG. 13 and FIG. 14 , the cutting nozzle unit 14 includes a mounting seat, a cutting nozzle 14 - 3 and a height sensing component. The cutting nozzle unit 14 is connected to the bottom of the lower connecting seat 18 through the mounting seat. The mounting base is provided with a cutting gas channel 14-13, and the mounting base is also provided with a connection line of a height sensing component and a cooling water channel 7 of a cutting nozzle 14-3. The cooling water channel 7 is used to cool the cutting nozzle 14-3 during cutting to prevent the cutting nozzle 14-3 from being damaged due to excessive temperature during a long cutting process. The cutting nozzle 14-3 is mounted on the mounting base through a nozzle locking nut 14-4, and a laser channel 14-11 is provided thereon, and the laser channel 14-11 is connected to a cutting gas channel 14-13 on the mounting base.

Further, the height sensing component is 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 seat through a nut 14-5, and is arranged around the cutting nozzle 14-3, and 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 seat, and is connected to the spring probe 14-8 through a wire. The connector 14-9 and the spring probe 14-8 constitute a connection circuit of the height sensing component, and 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 is in contact with 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, which is arranged around the cutting nozzle 14-3 and has a through groove thereon. A metal connector is arranged in the through groove, and the upper end of the metal connector is connected to the spring probe 14-8, and the lower end is in contact with the induction nozzle 14-7, so as to realize the electrical connection between the spring probe 14-8 and the induction nozzle 14-7. Specifically, the metal connector includes a metal column (such as a copper column) and a metal rod connected to each other, the metal column is located at the upper end of the annular ceramic body, the metal rod is passed through the through groove, the metal column is connected to the spring probe, and the lower end of the metal rod is in contact with the induction nozzle 14-7. More specifically, the connector 14-9 is connected to the external signal interface 10. As shown in FIG. 2, the signal interface 10 is arranged outside the laser cutting head body 11 for connecting to an external controller. A capacitor is formed between the height sensor composed of the ceramic ring 14-6 and the induction nozzle 14-7 and the metal workpiece to be cut. When the distance from the induction nozzle 14-7 to the workpiece to be cut changes, the potential of the capacitor will change, and the changed signal is transmitted to the external controller through the connecting line. The controller adjusts the height between the entire laser cutting processing head and the metal workpiece to be cut according to the received electrical signal, so that the height from the induction nozzle 14-7 to the surface of the workpiece to be cut remains unchanged, thereby achieving fixed height cutting and effectively ensuring the stability of the cutting quality. Specifically, the connecting piece 14-9 is a copper column, and the spring probe 14-8 and the induction nozzle 14-7 are both made of metal materials, such as copper.

The combined laser cutting processing head of the present application is generally installed on a machine tool or a robot when in use. The three-dimensional motion mechanism of the machine tool or the robot drives the cutting head to perform three-dimensional motion, and then the workpiece is cut according to the prescribed path. During cutting, the height sensor composed of a ceramic ring 14-6 and a sensing nozzle 14-7 is used to sense the height signal from the cutting head to the workpiece to be cut. The controller in the three-dimensional motion mechanism of the machine tool or the robot drives the three-dimensional motion mechanism to move according to the signal transmitted by the height sensor, and then adjusts the height of the cutting head to the workpiece to be cut, thereby ensuring that the focus of the laser beam is always located at the same position of the workpiece to be cut during 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, so that the distance from the cutting head to the surface of the workpiece to be cut remains basically unchanged. Specifically, the mounting seat can be an integral structure or a split structure, including an upper seat body 14-1 and a lower seat body 14-2, and the lower seat body 14-2 It is sleeved on the outside of the lower end of the upper seat body 14-1.

As shown in FIG15 , a cutting gas channel 14-13, a combustion gas channel 14-10 and a combustion-supporting gas channel 14-12 are provided on the mounting seat. The cutting gas channel 14-13 is connected to an external cutting gas source for providing cutting gas to the cutting nozzle. The combustion gas channel 14-10 is connected to an external combustion gas source for providing combustion gas to the cutting nozzle. The combustion-supporting gas channel 14-12 is connected to an external combustion-supporting gas source for providing combustion gas to the cutting nozzle. Among them, the cutting gas channel 14-13 is connected to a laser channel 14-11 on the cutting nozzle, so that the cutting gas and the laser beam are transmitted together through the laser channel of the cutting nozzle to the surface of the workpiece to be cut to achieve cutting. When a traditional laser cutting head is used for thin plate laser cutting processing, the cutting gas is generally oxygen, nitrogen, argon or compressed air, etc., and combustion gas and combustion-supporting gas are not required. When using a flame-assisted laser cutting head for thick plate laser cutting, the cutting gas is generally general oxygen or high-purity oxygen, and the combustion gas is generally organic combustion gas such as propane, acetylene, and natural gas. The combustion gas pressure is generally lower than the pressure of low-pressure oxygen, which is 0.05bar to 0.4bar. The combustion-supporting gas is low-pressure oxygen with a pressure of 0.1bar to 2bar. The low-pressure oxygen is used as a combustion-supporting agent to react with the combustion gas to produce a high-temperature flame.

Specifically, as shown in Figure 16, the cutting nozzle 14-3 is a flame-assisted laser cutting nozzle, which includes a nozzle body 19-1, a laser channel 14-11 is opened 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 an inlet for the cutting gas and the laser beam, and the lower end serves as an outlet for the cutting gas and the laser beam, and the lower end is designed as a Laval structure; a mixed gas channel 19-2 is also opened on the nozzle body 19-1, and the mixed gas channel 19-2 is opened on the side of the nozzle body. The mixed gas channel 19-2 is connected to the combustion gas channel 14-10 and the combustion-supporting gas channel 14-12 on the mounting seat, and is used to output the mixed gas of the combustion gas and the combustion-supporting gas from the lower end of the nozzle body 19-1. By designing the Laval structure, the cutting gas is accelerated continuously while passing through the Laval structure, and the flow velocity reaches a supersonic state when it is finally emitted, thereby ensuring that the cutting gas has a high speed, purity and stiffness within the entire workpiece thickness range, thereby making the cutting efficiency higher and the slag blowing effect better. In addition, the slender Laval structure effectively reduces the nozzle diameter and significantly reduces the consumption of the main cutting gas, thereby improving the cutting quality while reducing the cutting cost.

Specifically, the Laval structure is a structure that first contracts and then straightens and then expands, or first contracts and then expands. The present application prefers a structure that first contracts and then straightens and then expands, that is, it includes a contraction section, a straight section and an expansion section arranged in sequence 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 straight 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, which is embedded in 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 is a plurality of strip grooves arranged vertically and evenly distributed along the circumference of the nozzle body, and the strip grooves are connected to the annular groove.

Furthermore, the flame-assisted laser cutting nozzle may further include a gas mixing unit, which is connected to the combustion gas channel 14-10 and/or the combustion-supporting gas channel 14-12 on the mounting base. As shown in FIG. 17 , the gas mixing unit includes a gas mixing structure 14-14 and an air intake structure 14-15 connected to each other, and the air intake structure 14-15 is used to feed the combustion gas and the combustion-supporting gas into the gas mixing structure through different inlets. In 14-14, the gas mixing structure 14-14 is used to mix the combustion gas and the combustion-supporting gas and 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.

Specifically, the air intake structure 14-15 is an injection-suction structure, which includes two input ports, one of which is used to input combustion-supporting gas, and the other is used to input combustion gas. The gas mixing structure 14-14 is provided with a mixing chamber, which includes a contraction section, a straight section and an expansion section arranged in sequence, wherein the contraction section serves as the input end of the combustion gas and the combustion-supporting gas, the straight section serves as the mixing section of the combustion gas and the combustion-supporting gas, and the expansion section serves as the output end of the combustion gas and the combustion-supporting gas. Specifically, the two input ports of the air intake structure 14-15 are both connected to the mixing chamber of the gas mixing structure 14-14, and one of the input ports is arranged in the middle of the injection-suction structure for inputting combustion-supporting gas, and the other input port is arranged around the input port in the middle for inputting combustion gas, and the pressure of the combustion-supporting gas is higher than that of the combustion gas.

During cutting, the combustion-supporting gas with a higher pressure first enters the gas mixing structure from an input port of the jet-suction air intake structure, so that a certain degree of negative pressure is formed at the inlet of the gas mixing structure, and then the combustion gas with a lower pressure is sucked into the gas mixing structure under the negative pressure environment, and mixed with the combustion-supporting gas in the gas mixing structure to form a mixed gas, which then flows into the mixed gas channel of the nozzle through the channel on the mounting seat. The jet-suction structure of the cutting nozzle can not only reduce the pressure of the combustion gas used for cutting, but also the longer gas mixing structure can make the mixing path of the combustion-supporting gas and the combustion gas longer and more uniform, so that the mixed gas can burn more fully and release more heat energy, thereby effectively improving the cutting speed of metal plates and the energy utilization rate during the cutting process.

Furthermore, the cutting nozzle 14-3 is a laser cutting nozzle, as shown in FIG18 , the laser cutting nozzle includes a laser cutting nozzle body, a laser channel 14-16 is opened in the middle of the laser cutting nozzle body and is coaxially arranged with the laser cutting nozzle body, the upper end of the laser channel 14-16 serves as an inlet for cutting gas and laser beam, and the lower end serves as an outlet for cutting gas and laser beam. A cutting gas channel 14-17 is also opened on the laser cutting nozzle body, the cutting gas channel 14-17 is opened on the side of the laser cutting nozzle body, and is arranged around the laser channel 14-16, and the cutting gas channel 14-17 is connected to the cutting gas channel on the mounting seat; or, the laser channel 14-16 is also used as a cutting gas channel, that is, the cutting gas and the laser beam pass through the laser channel 14-16 at the same time.

The above-mentioned cutting nozzle unit 14 with a flame-assisted laser cutting nozzle can realize flame-assisted laser cutting of thick metal materials, and the above-mentioned cutting nozzle unit 14 with a laser cutting nozzle can realize laser cutting of thin plate materials. When the conversion of two cutting modes is required, it is only necessary to replace the cutting nozzle unit 14 with the corresponding cutting nozzle. Since the cutting nozzle unit 14 is detachable, when the cutting mode needs to be changed, the entire cutting nozzle unit 14 is removed as a whole, and then the cutting nozzle unit 14 with other modes is installed. At the same time, the collimating mirror, focusing mirror, etc. in the optical system unit can be replaced as needed. Of course, since the nozzle designed in this application is detachably connected to the mounting seat, the height sensor (the whole composed of the ceramic ring 14-6 and the sensor nozzle 14-7) is detachably connected to the mounting seat. Therefore, the height sensor can be removed first, and then the nozzle (such as the flame-assisted laser cutting nozzle) is removed, and then another nozzle (such as the laser cutting nozzle) is replaced, and then the height sensor is installed. The change of the cutting mode can be realized, so that the laser cutting of thin plate metal can be performed on the same laser cutting equipment. The advantages of the material combined with the advantages of flame-assisted laser cutting of thick plate metal materials have greatly expanded the applicability of the cutting head. Flame-assisted laser cutting nozzles and laser cutting nozzles can be divided into many different models according to different calibers. When cutting, different types and models of cutting nozzles are selected according to the thickness of the workpiece to be cut. In the actual working process, nozzles of any size and specification can be replaced, and the mounting seat, height sensor, gas path, etc. can 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 scope of cutting application can be greatly improved, and the investment in equipment can be reduced.

Furthermore, the laser processing cutting head provided in the present application also includes a cooling unit, which includes a main cooling water channel 3, and 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, which is used to cool the laser cutting head body 11 and the optical system unit 13 to prevent the local temperature of the cutting head from being too high during the cutting process and damaging the components of the cutting head.

Furthermore, the laser cutting head body 11 is also provided with an optical fiber connector 1, which can adopt a standard connector method (such as QBH, QCS and QD, etc.), and is used to connect to an external laser to guide the laser beam emitted by the laser into the optical system unit 13. The optical fiber connector 1 is arranged at the top middle position of the laser cutting head body 11, and the optical fiber interface of the laser is inserted into the optical fiber connector 1 and fixed and locked, and the optical fiber connector 1 guides the laser beam output by the optical fiber into the optical system unit 13.

The cutting head provided in the present application is in the flame-assisted laser cutting mode. Before starting cutting, the combustion gas and low-pressure oxygen are first input into the mixed gas channel 19-2 of the cutting nozzle 14-3 through the combustion gas channel 14-10 and the combustion-supporting gas channel 14-12. After the two gases are mixed, they are transported to the bottom of the lower end of the cutting nozzle 14-3 through the mixed gas channel 19-2 of the cutting nozzle 14-3 and ignited to generate a high-temperature flame. Subsequently, the cutting oxygen and the laser beam are output to the surface of the workpiece to be cut through the laser channel 14-11 of the cutting nozzle 14-3 for cutting. Different from the flame-assisted laser cutting mode, when using the laser cutting mode, after replacing the cutting nozzle unit 14 or the cutting nozzle 14-3, it is only necessary to output the cutting gas and the laser beam through the cutting nozzle to the surface of the workpiece to be cut, without the need to introduce the combustion gas and the combustion-supporting gas. In addition, when using the laser cutting mode for thin plate cutting, the cutting gas can be not only general oxygen or high-purity oxygen, but also nitrogen, argon or even compressed air. When using gas-assisted laser cutting, the cutting gas is generally general oxygen or high-purity oxygen.

The following are examples of the present application.

Example 1

When using the combined laser cutting processing head provided in this application for flame-assisted laser cutting, install a flame-assisted laser cutting nozzle, and install the combined laser cutting processing head on a machine tool or robot, and connect it to the corresponding controller of the machine tool or robot. Set the nozzle height to 6mm, use 9bar high-pressure oxygen as the cutting gas, and use a protective mirror in the optical system unit with a diameter of 38mm, a collimating mirror with a diameter of 38mm, a focal length of 100mm, a focusing mirror with a diameter of 37mm, and a focal length of 500mm. Use a 6kW fiber laser with a core diameter of 50μm and a beam quality BPP of 1.96 as the light source. After the laser beam emitted by the laser with the above parameters passes through the optical system consisting of a collimating mirror and a focusing system, and a composite cutting head, its focus is located below the surface of the workpiece, and at the same time, through the dynamic adjustment unit The focus of the laser beam is adjusted to be 20 mm below the workpiece surface.

Subsequently, propane and oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, and the gas pressures are set to 0.4 bar and 0.5 bar respectively. The input propane and oxygen are mixed and ignited at the outlet of the flame-assisted cutting nozzle. The generated high-temperature flame heats the workpiece to be cut. Then the cutting function is started, and a focused laser beam of a certain power and 9 bar of high-pressure 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 route driven by the machine tool, and 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 cutting workpiece, so that the processing head is kept 6 mm above the surface of the workpiece, and finally flame-assisted laser cutting of metal materials with a thickness of 60 mm is achieved at a speed of 0.9 m/min.

Example 2

When using the combined laser cutting processing head provided in the present application for laser cutting, the cutting nozzle of the combined laser cutting processing head is replaced with a laser cutting nozzle, the combined laser cutting processing head is installed on a machine tool or a robot, and connected to the corresponding controller of the machine tool or the robot, the cutting path is set and the nozzle height is set to 1mm, the cutting gas is 2bar oxygen, the laser adopts a fiber laser with a power of 4kW, a core diameter of 50μm, and a beam quality BPP of 1.3, the protective mirror in the optical system unit has a diameter of 30mm, a collimator mirror has a diameter of 30mm, a focal length of 100mm, a focusing mirror has a diameter of 30mm, and a focal length of 200mm, and the laser and optical system with the above parameters are used to make the focus of the laser beam below the surface of the workpiece, and at the same time, the dynamic adjustment unit is adjusted to make the focus of the laser beam 3mm below the surface of the workpiece.

Then the cutting function is started, and a laser beam of a certain power and 2bar 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 route, and the capacitance value generated by the height difference between the sensing nozzle of the processing head and the cutting workpiece is used. 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 cutting workpiece, so that the processing head remains 1mm above the surface of the workpiece, and finally achieves laser cutting of low-carbon steel with a thickness of 8mm at a speed of 2m/min.

Example 3

Use the combined laser cutting processing head provided in the present application to perform perforation and cutting on a low-carbon steel plate with a thickness of 30 mm by flame-assisted laser cutting. First, install the flame-assisted laser cutting nozzle in the combined laser cutting processing head, install the combined laser cutting processing head on a machine tool or a robot, and connect it to the corresponding controller of the machine tool or the robot. The nozzle height is set to 5 mm, the cutting gas uses 7 bar oxygen, the laser uses a 4 kW fiber laser with a core diameter of 50 μm and a beam quality BPP of 1.3, the diameter of the protective mirror in the optical system unit is 38 mm, the diameter of the collimating mirror is 38 mm, the focal length is 150 mm, the diameter of the focusing mirror is 38 mm, and the focal length is 400 mm. Through the laser and optical system with the above parameters, the focus of the laser beam is located below the surface of the workpiece, and at the same time, the focus of the laser beam is adjusted by the dynamic adjustment unit to be located 10 mm below the surface of the workpiece.

Then, 0.4 bar propane and 0.6 bar oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel. The two gases are mixed and ignited at the outlet of the flame cutting nozzle. The machine burns to generate a high-temperature flame, then inputs a laser beam and cutting oxygen with a pressure of 7 bar into the laser channel of the cutting nozzle to perforate the predetermined position, and then cuts the workpiece along the preset cutting path at a speed of 0.9 m/min.

Example 4

Use the combined laser cutting processing head provided by the present application and the injection-absorption flame-assisted laser cutting nozzle to cut a low-carbon steel plate with a thickness of 30 mm. First, install the flame-assisted laser cutting nozzle in the combined laser cutting processing head, install the combined laser cutting processing head on a machine tool or a robot, and connect it to the corresponding controller of the machine tool or the robot. The cutting gas uses 7 bar cutting oxygen, the nozzle height is set to 5 mm, the laser uses a 3kW fiber laser with a core diameter of 14 μm and a beam quality ^M2 of 1.1. The diameter of the protective mirror in the optical system unit is 30 mm, the diameter of the collimator is 30 mm, the focal length is 150 mm, the diameter of the focusing mirror is 30 mm, and the focal length is 400 mm. The laser and optical system with the above parameters make the focus of the laser beam below the surface of the workpiece, and at the same time, the focus of the laser beam is located 10 mm below the surface of the workpiece in combination with the adjustment of the dynamic adjustment unit.

Then, 0.1 bar propane and 1 bar 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 produce a high-temperature flame. Then, the laser beam and cutting oxygen with a gas pressure of 7 bar are input into the laser channel of the cutting nozzle to perforate the predetermined position, and then the workpiece is cut along the preset cutting path at a speed of 1 m/min.

Example 5

Use the combined laser cutting processing head provided by this application, adopt the flame-assisted laser cutting mode, and cut non-ferrous metals such as copper or copper alloy with a thickness of 12mm. Before starting cutting, install the flame-assisted laser cutting nozzle, and install the combined laser cutting processing head on the machine tool or robot, and connect it to the corresponding controller of the machine tool or robot, set the nozzle height to 4mm, use oxygen with an air pressure of 12bar for cutting gas, use a green or blue laser with a power of 1kW for the laser, and the diameter of the protective mirror in the optical system unit is 32mm, the diameter of the collimating mirror is 32mm, the focal length is 100mm, the diameter of the focusing mirror is 32mm, and the focal length is 300mm. Through the laser and optical system with the above parameters, the focus of the laser beam is located below the surface of the workpiece, and the focus of the laser beam is located 5mm below the surface of the workpiece by adjusting the dynamic adjustment unit.

Subsequently, propane and oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, and the gas pressures are set to 0.4 bar and 0.5 bar respectively. The input propane and oxygen are mixed and ignited at the outlet of the flame-assisted cutting nozzle. The generated high-temperature flame heats the workpiece to be cut. Subsequently, a 1 kW green or blue laser beam and 12 bar of high-pressure 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 route driven by the machine tool, and 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 cutting workpiece, so that the processing head remains 4 mm above the surface of the workpiece, and 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.

Example 6

The combined laser cutting processing head provided by the present application adopts the flame-assisted laser cutting mode to cut non-ferrous metals such as aluminum or aluminum alloy with a thickness of 20 mm. Before starting cutting, install the flame-assisted laser cutting nozzle, and install the combined laser cutting processing head on the machine tool or robot, and connect it to the corresponding controller of the machine tool or robot, set the nozzle height to 3.5 mm, use high-pressure oxygen with an air pressure of 10 bar for the cutting gas, use an infrared fiber laser with a power of 3 kW for the laser, and the diameter of the protective mirror in the optical system unit is 32 mm, the diameter of the collimating mirror is 32 mm, the focal length is 100 mm, the diameter of the focusing mirror is 32 mm, and the focal length is 300 mm. The laser and optical system with the above parameters are used to make the focus of the laser beam below the surface of the workpiece, and the focus of the laser beam is 7 mm below the surface of the workpiece by adjusting the dynamic adjustment unit.

Subsequently, propane and oxygen are introduced into the mixed gas channel of the nozzle through the combustion gas channel and the combustion-supporting gas channel, and the gas pressures are set to 0.4 bar and 0.5 bar respectively. The input propane and oxygen are mixed and ignited at the outlet of the flame-assisted cutting nozzle. The generated high-temperature flame 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. At the same time, the combined laser processing head is driven by the machine tool or robot to move along the preset cutting route. 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 cutting workpiece, so that the processing head is kept 3.5 mm above the surface of the workpiece, and finally flame-assisted laser cutting of aluminum or aluminum alloy is achieved at a speed of 500 mm/min.

Example 7

The combined laser cutting processing head provided in the present application is used to cut a Q235 low-carbon steel plate with a thickness of 30 mm by a flame-assisted multi-focus laser cutting method. First, the flame-assisted laser cutting nozzle is installed in the combined laser cutting processing head, and the combined laser cutting processing head is installed on a machine tool or a robot and connected to the corresponding controller of the machine tool or the robot. The nozzle height is set to 4 mm, and the cutting gas uses 7 bar oxygen. The laser uses a 4kW fiber laser with a core diameter of 50 μm and a beam quality BPP of 1.3. The diameter of the protective mirror in the optical system unit is 38 mm, the diameter of the collimator mirror is 38 mm, the focal length is 100 mm, and the focusing mirror is a F400-F420 dual-focus focusing mirror with a diameter of 38 mm. The laser beam output by the laser is converted into a dual-focus laser beam through the laser and optical system with the above parameters. At the same time, the F400 focus of the dual-focus laser beam is adjusted by the dynamic adjustment unit to be located 5 mm below the surface of the workpiece.

Subsequently, 0.5 bar propane and 0.4 bar 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. Subsequently, a dual-focus laser beam and cutting oxygen with a gas pressure of 7 bar are input into the laser channel of the cutting nozzle to perforate the predetermined position. Then, the workpiece is cut along the preset cutting path at a speed of 1.3 m/min. There is basically no slag at the bottom of the cut workpiece, the average roughness of the cut section is about 25 μm, and the verticality of the section is about 87°.

Example 8

The combined laser cutting processing head provided in the present application is used to cut a Q235 low-carbon steel plate with a thickness of 160 mm by a flame-assisted multi-focus laser cutting method. First, the flame-assisted laser cutting nozzle is installed in the combined laser cutting processing head, and the combined laser cutting processing head is installed in the The cutting gas is 10 bar oxygen, the laser is a 6 kW fiber laser with a core diameter of 50 μm and a beam quality BPP of 1.96, the diameter of the protective mirror in the optical system unit is 38 mm, the diameter of the collimating mirror is 38 mm, the focal length is 100 mm, and the focusing mirror is a four-focus focusing mirror of F400-F440-F480-F520 with a diameter of 38 mm. The laser beam output by the laser and the optical system are transformed into a four-focus laser beam through the above parameters, and the F400 focus of the four-focus laser beam is located 15 mm below the workpiece surface through the adjustment of the dynamic adjustment unit.

Subsequently, 0.4 bar propane and 0.5 bar 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. Subsequently, a four-focus laser beam and cutting oxygen with a gas pressure of 10 bar are input into the laser channel of the cutting nozzle to perforate the predetermined position, and then the workpiece is cut along the preset cutting path at a speed of 0.4 m/min. There is basically no slag at the bottom of the cut workpiece, the average roughness of the cut section is 45 μm, and the verticality of the section is 85°.

Comparative Example 1

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

Comparative Example 2

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

By comparing Example 1 with Example 7 of the present application, it can be seen that the flame-assisted multi-focus laser cutting technology provided by the present application can use lower laser power (4kW vs 5.5kW) and faster cutting speed (1.3m/min vs 1.0m/min) to achieve the cutting of thick plates under the premise of the same thickness of the workpiece to be cut. By comparing Example 2 with Example 8 of the present application, it can be seen that under the same laser power, the flame-assisted multi-focus laser cutting technology provided by the present application can cut thicker (160mm vs 140mm) workpieces at a faster cutting speed (0.4m/min vs 0.3m/min).

The processing head provided in this application is not only suitable for conventional single-focus laser cutting, but also very suitable for multi-focus laser cutting, especially flame-assisted multi-focus laser cutting. When flame-assisted multi-focus laser cutting is performed, the focal depth of the laser beam is larger, the divergence angle is smaller, and the spot diameter is kept at a small value within the focal depth range (the spot diameter is 0.5mm to 1.5mm). Therefore, during the cutting process, the laser beam maintains a high energy density in a large range (10mm to 200mm) in the thickness direction of the workpiece, ensuring that the focus of the laser beam can penetrate a long distance below the surface of the workpiece (negative defocus), and thus obtain a higher laser cutting efficiency and slit quality. This application utilizes a multi-focus laser beam with a large focal depth (30mm to 80mm) and a small spot diameter (0.5mm to 1.5mm), combined with a cutting nozzle to accelerate high-pressure oxygen, and can use a lower power (less than 2kW) laser to cut thicker metal materials, thereby greatly improving cutting efficiency, improving slit quality, and reducing cutting costs. At the same time, because the focus spot diameter of the laser beam is small enough (0.5mm~1.5mm) and the focal depth is long enough (30mm~80mm), the use of a smaller diameter nozzle can also allow the multi-focus laser beam to pass through the cutting nozzle without energy loss, and the focus of the multi-focus laser beam can penetrate deep into the cutting workpiece to achieve negative defocus cutting. In addition, the multi-focus beam with a larger focal depth has a larger focus adjustment range. According to the needs of different cutting processes, the focus of the laser beam can be adjusted to different positions above, on the surface or inside the cutting workpiece, so as to meet the cutting needs of metal materials of different thicknesses and types.

This application not only breaks through the limitations of high equipment cost and low cutting efficiency of traditional laser cutting process in the field of cutting medium-thickness and thick-thickness metal materials, but also overcomes the technical bottleneck of poor quality of flame-assisted laser cutting process when cutting thin metal materials. It can meet the needs of high-quality cutting of metal materials of different thicknesses without the need for very high-power laser output.

It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

A combined laser cutting processing head with a replaceable cutting nozzle, characterized in that it comprises 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 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 emitted by the optical system unit (13); the optical system unit (13), the connecting unit (18) and the cutting nozzle unit (14) are arranged in sequence from top to bottom, wherein the optical system unit (13) ) is arranged in the laser cutting head body (11) and is replaceable, and is used to transform the laser beam input from the outside and guide it 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). It is used to guide 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) and is used to guide the laser beam and cutting gas to the surface of the workpiece to be cut, so as to achieve cutting of the workpiece to be cut.
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 1 is characterized in that the cutting nozzle unit (14) includes a mounting seat, a cutting nozzle (14-3) and a height sensing component, the mounting seat is provided with a cutting gas channel (14-13), the cutting nozzle (14-3) is detachably mounted on the mounting seat, and is provided with a laser channel (14-11), which is connected to the cutting gas channel (14-13) on the mounting seat; preferably, the height sensing component is a capacitive height adjustment component, an arc voltage height adjustment component or a mechanical height adjustment component; the height sensing component is preferably The invention relates to a capacitance height adjustment component, comprising a ceramic ring (14-6), an induction nozzle (14-7), a spring probe (14-8) and a connecting piece (14-9); the ceramic ring (14-6) is detachably mounted on the bottom of the mounting seat and is arranged around the cutting nozzle (14-3); the induction nozzle (14-7) is mounted on the bottom of the ceramic ring (14-6) and is arranged around the cutting nozzle (14-3); the connecting piece (14-9) is mounted on the mounting seat 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); The lower end of the ceramic ring (14-6) contacts the induction nozzle (14-7), and the spring probe (14-8) is electrically connected to the induction nozzle (14-7).
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 2 is characterized in that a combustion gas channel (14-10) and a combustion-supporting gas channel (14-12) are also provided on the mounting seat, and the combustion gas channel (14-10) is used to transport combustion gas to the cutting nozzle (14-3), and the combustion-supporting gas channel (14-12) is used to transport combustion gas to the cutting nozzle (14-3).
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 2 is 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 comprises a nozzle body (19-1), a laser channel 1 (14-11) is provided in the middle of the nozzle body (19-1), and a mixed gas channel (19-2) is provided on the side, the laser channel 1 (14-11) is used for allowing the laser beam and cutting gas to pass through, the mixed gas channel (19-2) is used for allowing the combustion gas and the combustion-supporting gas to pass through, and the lower end of the laser channel 1 (14-11) is designed as a Laval structure; the laser cutting nozzle comprises a laser cutting nozzle body, a laser channel 2 (14-16) is provided in the middle of the laser cutting nozzle body, for allowing the laser beam and cutting gas to pass through; or the laser cutting nozzle body is provided with a laser channel 2 (14-16) in the middle and a cutting gas channel 2 (14-17) is provided on the side, wherein the laser channel 2 (14-16) is used for passing the laser beam, and the second cutting gas channel (14-17) is used for passing the cutting gas; preferably, the flame-assisted laser cutting nozzle also includes a gas mixing unit, which is connected to the combustion gas channel (14-10) and/or the combustion-supporting gas channel (14-12) on the mounting seat; preferably, the gas mixing unit includes a gas mixing structure (14-14) and an air intake structure (14-15) connected to each other, and the air intake structure (14-15) is used to send the combustion gas and the combustion-supporting gas into the gas mixing structure (14-14) through different inlets, and the gas mixing structure (14-14) is used to mix the combustion gas and the combustion-supporting gas and 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 seat; preferably, the air intake structure (14-15) is an injection-suction structure, which includes two input ports, one of which is used to input the combustion-supporting gas, and the other is used to input the combustion gas.
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 1 is characterized in that the optical system unit (13) includes a collimating lens assembly (16) and a focusing lens assembly (17) arranged up and down, and a protective lens assembly (15) is provided above the collimating lens assembly (16) and below the focusing lens assembly (17); preferably, the laser cutting head body (11) is provided with a plurality of horizontal mounting grooves from top to bottom, and the collimating lens assembly (16), the focusing lens assembly (17) and the protective lens assembly (15) are arranged as a whole in the corresponding horizontal mounting grooves in a plug-in manner.
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 5 is characterized in that the collimating lens assembly (16) includes a collimating lens seat (16-2) and a collimating lens (16-3), the collimating lens seat (16-2) is provided with a lens mounting groove, and the collimating lens (16-3) is installed in the lens mounting groove of the collimating lens seat (16-2) for collimating the laser beam; the collimating lens seat (16-2) is also connected to a lens seat connector (16-5), and the collimating lens seat (16-2) is connected to the laser beam focusing unit (12) through the lens seat connector (16-5).
The combined laser cutting processing head with replaceable cutting nozzle according to claim 5 is characterized in that the focusing mirror assembly (17) comprises a focusing mirror (17-5), a focusing mirror seat (17-7), a mirror seat connecting plate (17-2) and an elastic mounting member (17-4), wherein the focusing mirror (17-5) is fixed in the focusing mirror seat (17-7); a mounting groove is provided in the circumferential direction of the outer side of the focusing mirror seat (17-7), the elastic mounting member (17-4) is arranged in the circumferential direction of the outer side of the focusing mirror seat (17-7) and is embedded in the mounting groove, and both ends of the elastic mounting member (17-4) are fixed to the mirror seat connecting plate (17-2). The lens seat (17-7) is provided with a positioning plate (17-3) on one side of the focusing lens seat (17-7) facing the lens seat connecting plate (17-2); the lens seat connecting plate (17-2) is detachably connected to the laser cutting head body (11), and is provided with a positioning groove that cooperates with the positioning plate (17-3); an adjusting rod (17-1) is also installed on the lens seat connecting plate (17-2), one end of the adjusting rod (17-1) is in contact with the outer side surface of the focusing lens seat (17-7), and the relative position of the focusing lens seat (17-7) and the lens seat connecting plate (17-2) is adjusted by the action of the adjusting rod (17-1).
The combined laser cutting processing head with replaceable cutting nozzle according to claim 7 is characterized in that the focusing lens (17-5) is a multi-focus focusing lens. Preferably, the multi-focus focusing lens It is a single lens, a combined lens, a diffractive lens, a reflective lens or a metal lens; preferably, the multi-focal focusing lens is a single plano-convex lens, one side of which is a flat surface and the other side is a convex surface, the convex surface is composed of a plurality of focal surfaces with different curvatures, and the curvature of each focal surface gradually increases from the center of the multi-focal focusing lens to the outside, and two adjacent focal surfaces are transitioned by a transition surface.
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 5 is characterized in that the protective mirror assembly (15) includes a protective mirror seat (15-2) and a protective mirror (15-4), the protective mirror (15-4) is installed on the protective mirror seat (15-2) through a fixing assembly, the protective mirror seat (15-2) is connected to a protective mirror connecting plate (15-1), and the protective mirror connecting plate (15-1) is detachably connected to the laser cutting head body (11).
The combined laser cutting processing head with a replaceable cutting nozzle as described in claim 5 is characterized in that the laser beam focusing unit (12) includes a motor (12-12), a screw (12-6), a guide rail (12-3) and a guide rail slider (12-4), wherein the motor (12-12) is mounted on the laser cutting head body (11) and is connected to the screw (12-6) for driving the screw (12-6) to rotate, and the screw (12-6) is threadedly engaged with the mirror seat connector (16-5); the guide rail (12-3) is mounted on the laser cutting head body (11) and is slidably engaged with the guide rail slider (12-4), and the guide rail slider (12-4) is connected to the mirror seat connector (16-5) via a guide rail connecting plate (12-5).