Total reflection type light-in-feed laser processing head

Abstract

The application discloses a full-reflection type light-in-material feeding laser processing head and belongs to the technical field of laser processing, comprising: aspherical mirrors and plane mirrors placed in sequence along the direction of a laser light path; wherein the aspherical mirrors comprise a plurality of reflection regions, and the surface types of the reflection regions are all different, so as to split incident laser light; the plane mirrors comprise a plurality of reflection planes, and the inclination angles of the reflection planes are all different, and the included angles between the reflected light rays of the reflection planes and the axis of a material feeding device are all the same, so that the reflected light rays of the reflection planes are uniformly focused on a working surface, and the wire / powder material coaxially fed by the material feeding device is processed; compared with the existing light-in-material feeding laser processing head, the application significantly reduces the number of optical components, has good light path stability, realizes a light-weight coaxial wire / powder feeding laser processing head with good light path stability, and can be widely applied to the processing field of laser additive manufacturing.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology, and more specifically, relates to a total internal reflection type laser processing head for in-light material delivery. Background Technology

[0002] With the development of advanced laser manufacturing technology, higher demands are being placed on laser processing systems to meet the manufacturing needs of industries such as automobiles, electronics, electrical appliances, aerospace, metallurgy, and machinery manufacturing. In-light material feeding technology refers to using different beam splitting techniques to center and vertically spray material onto the processing surface, ensuring the laser beam is coaxial with the material's centerline. In-light material feeding laser processing heads offer superior processing performance due to their excellent material feeding directionality, uniform material heating, and strong laser-material coupling. Therefore, researching an in-light material feeding laser processing head is of great significance.

[0003] Existing laser processing heads with internal optical feeding generally use coaxial wire / powder feeding processing. Currently, coaxial wire / powder feeding processing mainly includes two methods: ring-shaped internal optical wire / powder feeding processing and beam-splitting internal optical wire / powder feeding processing. Traditional beam splitting methods generally use conical mirrors, prisms, adjustment mirrors, etc. for beam splitting, which requires many lenses, has poor optical path stability, and is not conducive to the lightweight and high-quality development of laser processing heads. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a total internal reflection optical material feeding laser processing head, the purpose of which is to provide a lightweight coaxial wire / powder feeding laser processing head with better optical path stability.

[0005] To achieve the above objectives, the present invention provides a total internal reflection type laser processing head for in-light material delivery, comprising: an aspherical mirror and a plane mirror placed sequentially along the laser beam path;

[0006] The aspherical mirror has N reflecting areas on its reflecting surface; the plane mirror has N reflecting planes that correspond one-to-one with the N reflecting areas, and the plane mirror is hollow to accommodate the feeding device.

[0007] Each of the aspherical reflector regions has a different surface shape, which is used to split the incident laser beam to obtain N laser beams, which are then incident on their respective reflective planes.

[0008] The tilt angles of each reflecting plane of the plane mirror are different, and the angle between the reflected light from each reflecting plane and the axis of the feeding device is the same. This is used to uniformly focus the reflected light from each reflecting plane onto the working surface so as to process the material coaxially fed by the feeding device.

[0009] Where N≥2; the feeding device includes: a wire feeding device or a powder feeding device.

[0010] More preferably, the surface shape of each reflecting region of the aspherical mirror is a revolution ellipsoid;

[0011] For any reflecting region S of an aspherical mirror, its surface shape satisfies the following condition: the ellipsoid obtained by rotating an ellipse with foci at points C and D about axis CD.

[0012] Wherein, point C is the location of the laser source of the incident laser; point D is the spatially symmetrical point of the laser focusing point on the working surface with respect to the reflection plane S' of the plane mirror; and the reflection plane S' is the reflection plane corresponding to the reflection region S.

[0013] Further optimization involves ensuring that the surface shape of each reflecting region of the aspherical mirror is a freeform surface; for any reflecting region S, its surface shape is determined in the following way:

[0014] S1. Initialize the surface shape of the reflection region S;

[0015] S2. Divide the cross-section of the incident laser source on the reflection region S into an equal-energy grid, thereby forming corresponding grid points on the reflection region S;

[0016] S3. Based on the relationship that the line vector connecting any two adjacent grid points in the reflection region S is perpendicular to the average value of the normal vectors at these two grid points, a set of linear equations is established to obtain the three-dimensional position data of each grid point in the reflection region S, so as to update the surface shape of the reflection region S. Here, the normal vector at any grid point in the reflection region S is the direction of the angle bisector between the incident ray and the reflected ray at that grid point. There is a one-to-one mapping relationship between the grid points in the reflection region S and the target grid points. The incident ray at a grid point in the reflection region S is reflected to the corresponding target grid point after passing through that grid point in the reflection region S. The target grid points are obtained by dividing the light spot on the working surface into grids according to preset requirements, and then spatially symmetrically dividing the grid points on the working surface about the plane mirror to obtain the corresponding target grid points.

[0017] S4. Repeat steps S2-S3 for iteration until the number of iterations reaches the preset number of iterations or the calculation result converges. At this time, the surface shape of the reflection region S is the surface shape of the desired reflection region S.

[0018] More preferably, the tilt angle of any reflecting plane S' of the plane mirror is determined by the following method:

[0019] Based on the angle θ between the reflected ray from the preset reflective plane S' and the axis of the feeding device, the direction of the reflected ray from the reflective plane S' is obtained;

[0020] Based on the relationship that the angle between the straight line O1O2 and the incident ray of the reflecting plane S' is equal to θ, the direction of the incident ray of the reflecting plane S' is obtained;

[0021] Calculate the direction of the angle bisector between the incident ray and the reflected ray of the reflecting plane S', obtain the direction of the normal vector of the reflecting plane S', and thus obtain the tilt angle of the reflecting plane S'.

[0022] Wherein, the straight line O1O2 is the line connecting the center point O1 of the aspherical mirror and the center point O2 of the plane mirror.

[0023] More preferably, the aspherical mirror has a high-reflectivity film coated on its reflective surface.

[0024] More preferably, the aspherical mirror is provided with a water-cooling channel.

[0025] More preferably, the plane mirror is provided with a water-cooling channel.

[0026] More preferably, the above-mentioned total internal reflection optical material feeding laser processing head further includes: a protective mirror disposed along the optical path direction behind the planar reflector and in front of the working surface.

[0027] More preferably, the protective mirror is a hollow ring-shaped protective mirror, which is composed of multiple independently pluggable fan-shaped protective mirrors.

[0028] Alternatively, the protective mirror is a hollow double-layer protective mirror structure, including an inner protective mirror away from the working surface and an outer protective mirror close to the working surface; wherein, the inner protective mirror is a hollow annular protective mirror; the outer protective mirror is a hollow annular protective mirror, which is spliced ​​together from multiple independently pluggable fan-shaped protective mirrors.

[0029] More preferably, N = 4.

[0030] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0031] 1. This invention provides a total internal reflection optical feeding laser processing head, comprising an aspherical reflector and a plane reflector placed sequentially along the laser beam path; the aspherical reflector includes multiple reflection regions, each with a different surface shape, to split the incident laser beam; the plane reflector includes multiple reflection planes, each with a different tilt angle, and the angle between the reflected light from each reflection plane and the axis of the feeding device is the same, thereby focusing the reflected light from each reflection plane onto the working surface, realizing the processing of the wire / powder material coaxially fed by the feeding device; compared with existing optical feeding laser processing heads, this invention significantly reduces the number of optical components, has better optical path stability, and realizes a lightweight coaxial wire / powder feeding laser processing head with better optical path stability.

[0032] 2. Furthermore, the total internal reflection laser processing head provided by the present invention can have a surface shape of the reflection area of ​​the aspherical mirror that can be a rotating ellipsoid or a free-form surface, which can be adaptively selected according to the required spot type, and has a wide range of applications.

[0033] 3. Furthermore, the total internal reflection optical material delivery laser processing head provided by the present invention has a high reflectivity film coated on the reflective surface of the aspherical mirror, which can further improve the reflectivity and reduce the light loss.

[0034] 4. Furthermore, the total internal reflection optical material delivery laser processing head provided by the present invention, due to its total internal reflection structure, allows for the convenient setting of water-cooling channels on the aspherical mirror and / or plane mirror to cool the reflecting surface of the aspherical mirror, thereby improving the heat resistance efficiency of the laser processing head.

[0035] 5. Furthermore, the total internal reflection optical material feeding laser processing head provided by the present invention further includes: a protective mirror disposed along the optical path direction after the plane mirror and before the working surface, to prevent dust from contaminating the laser processing head.

[0036] 6. Furthermore, the total reflection optical in-line material feeding laser processing head provided by the present invention uses a hollow ring-shaped protective mirror, which is spliced ​​together from multiple independently pluggable fan-shaped protective mirrors, making it convenient and flexible to disassemble and avoiding the difficulty of disassembling and replacing the protective mirror.

[0037] 7. Furthermore, the total internal reflection optical material feeding laser processing head provided by the present invention uses a hollow double-layer protective mirror structure. The outer protective mirror is a hollow annular protective mirror, which is spliced ​​together by multiple independently pluggable fan-shaped protective mirrors, making it convenient and flexible to disassemble. The inner layer is a hollow annular protective mirror, which is used to protect the optical path. Replacing the protective mirror will not contaminate the optical path. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of a total internal reflection optical material feeding laser processing head provided in Embodiment 1 of the present invention;

[0039] Figure 2 This is a flowchart illustrating the design process of an aspherical reflecting mirror according to Embodiment 1 of the present invention.

[0040] Figure 3 This is a schematic diagram showing the tilt angles of each reflecting plane of the planar reflector provided in Embodiment 1 of the present invention;

[0041] Figure 4 This is a schematic diagram of the ellipsoidal surface shape design method for the reflecting region in an aspherical mirror provided in Embodiment 1 of the present invention;

[0042] Figure 5 This is a schematic diagram of the light spots at various points on the ellipsoidal surface of the aspherical mirror provided in Embodiment 1 of the present invention;

[0043] Figure 6 This is a schematic diagram of the structure of the protective mirror provided in Embodiment 1 of the present invention;

[0044] Figure 7 This is a schematic diagram of the light spot at various locations of the flat-top light spot provided in Embodiment 2 of the present invention;

[0045] Figure 8 This is a schematic diagram of the light spot at various locations of the concave light spot provided in Embodiment 2 of the present invention. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0047] To achieve the above objectives, the present invention provides a total internal reflection type optical material delivery laser processing head, comprising: an aspherical mirror and a plane mirror placed sequentially along the laser beam path;

[0048] The aspherical mirror has N reflecting areas on its reflecting surface; the plane mirror has N reflecting planes that correspond one-to-one with the N reflecting areas, and the plane mirror is hollow to accommodate the feeding device.

[0049] The aspherical mirror has different surface shapes in each reflecting region to split the incident laser beam into N beams, which are then incident on their respective reflecting planes. Specifically, the laser beams are divided into N equal parts, and each spot can present a similar ring or fan-shaped distribution. The radial energy distribution of the spot can be freely designed; it can be designed to be equal or to be higher on the outside and lower on the inside, depending on the specific requirements.

[0050] The tilt angles of each reflecting plane of the plane mirror are different, so that the angle between the reflected light from each reflecting plane and the axis of the feeding device is the same, thereby focusing the reflected light from each reflecting plane onto the working surface to process the material coaxially fed by the feeding device.

[0051] Wherein, N≥2; the feeding device includes: a wire feeding device or a powder feeding device, such as a hollow tube for guiding wire or powder, to ensure that the powder (wire) feeding structure is coaxial with the laser beam.

[0052] Compared to existing optical in-light material feeding laser processing heads, this invention significantly reduces the number of optical components, improves optical path stability, and realizes a lightweight coaxial wire / powder feeding laser processing head with good optical path stability. Furthermore, the invention adopts a total reflection structure, which also makes it easier to set up a water cooling channel, thereby effectively improving the heat resistance efficiency of the laser processing head.

[0053] To achieve precise control, the surface shape of each reflecting region (aspheric surface) in the aspheric mirror can be designed based on the point-to-point energy relationship. The surface shape of each reflecting region can be a revolution ellipsoid or a freeform surface.

[0054] In one alternative implementation, the surface shape of each reflecting region of the aspherical mirror is a rotational ellipsoid.

[0055] For any reflecting region S of an aspherical mirror, its surface shape satisfies the following condition: the ellipsoid obtained by rotating an ellipse with foci at points C and D about axis CD.

[0056] Wherein, point C is the location of the laser source of the incident laser; point D is the spatially symmetrical point of the laser focusing point on the working surface with respect to the reflection plane S' of the plane mirror; and the reflection plane S' is the reflection plane corresponding to the reflection region S.

[0057] In one optional implementation, the surface shape of each reflecting region of the aspherical mirror is a freeform surface; for any reflecting region S, its surface shape is determined in the following way:

[0058] S1. Initialize the surface shape of the reflection region S;

[0059] S2. Divide the cross-section of the incident laser source on the reflection region S into an equal-energy grid, thereby forming corresponding grid points on the reflection region S;

[0060] S3. Based on the relationship that the line vector connecting any two adjacent grid points in the reflection region S is perpendicular to the average value of the normal vectors at these two grid points, a set of linear equations is established to obtain the three-dimensional position data of each grid point in the reflection region S, so as to update the surface shape of the reflection region S. Here, the normal vector at any grid point in the reflection region S is the direction of the angle bisector between the incident ray and the reflected ray at that grid point. There is a one-to-one mapping relationship between the grid points in the reflection region S and the target grid points. The incident ray at a grid point in the reflection region S is reflected to the corresponding target grid point after passing through that grid point in the reflection region S. The target grid points are obtained by dividing the light spot on the working surface into grids according to preset requirements, and then spatially symmetrically dividing the grid points on the working surface about the plane mirror to obtain the corresponding target grid points.

[0061] S4. Repeat steps S2-S3 for iteration until the number of iterations reaches the preset number of iterations or the calculation result converges. At this time, the surface shape of the reflection region S is the surface shape of the desired reflection region S.

[0062] In one alternative implementation, the tilt angle of any reflecting plane S' of the plane mirror is determined in the following manner:

[0063] Based on the angle θ between the reflected ray from the preset reflective plane S' and the axis of the feeding device, the direction of the reflected ray from the reflective plane S' is obtained;

[0064] Based on the relationship that the angle between the straight line O1O2 and the incident ray of the reflecting plane S' is equal to θ, the direction of the incident ray of the reflecting plane S' is obtained;

[0065] Calculate the direction of the angle bisector between the incident ray and the reflected ray of the reflecting plane S', obtain the direction of the normal vector of the reflecting plane S', and thus obtain the tilt angle of the reflecting plane S'.

[0066] Wherein, the straight line O1O2 is the line connecting the center point O1 of the aspherical mirror and the center point O2 of the plane mirror.

[0067] In one alternative implementation, the aspherical mirror is coated with a high-reflectivity film on its reflective surface to improve reflectivity and reduce light loss.

[0068] In one alternative implementation, a water-cooling channel is provided on the aspherical mirror to cool the reflecting surface of the aspherical mirror, thereby improving the heat resistance efficiency of the laser processing head.

[0069] In one alternative implementation, a water-cooling channel is provided on the planar reflector to cool the reflective surface of the planar reflector, thereby improving the heat resistance efficiency of the laser processing head.

[0070] In one alternative embodiment, the aforementioned total internal reflection optical material feeding laser processing head further includes a protective mirror disposed along the optical path direction behind the planar reflector and in front of the working surface to prevent dust from contaminating the laser processing head.

[0071] In one optional embodiment, the protective lens is a hollow annular protective lens, composed of multiple independently pluggable fan-shaped protective lenses, facilitating flexible disassembly and avoiding the difficulty of replacing the protective lens. In another optional embodiment, the protective lens can also adopt a double-layer protective lens structure. The outer protective lens is a hollow annular protective lens with a drawer-type split structure, composed of multiple independently pluggable fan-shaped protective lenses, facilitating flexible disassembly; the inner layer is a hollow annular protective lens, used to protect the optical path, ensuring that the optical path is not contaminated when replacing the protective lens.

[0072] It should be noted that N is an integer greater than or equal to 2, and can take values ​​of 3, 4, 5, 6, 7, 8, etc., without limitation here; preferably, N = 4.

[0073] In summary, this invention can effectively optimize the optical path design, significantly reduce the number of optical components, significantly reduce the assembly difficulty of the laser processing head, and allow for the design of the radial energy distribution of the laser spot, greatly enhancing the flexibility of the laser processing head. It is suitable for high-power laser processing cladding and welding processes and can be widely applied in laser processing fields such as laser additive manufacturing.

[0074] To further illustrate the total internal reflection optical material delivery laser processing head provided by the present invention, the following detailed description is provided in conjunction with specific embodiments:

[0075] Example 1

[0076] like Figure 1 As shown, this embodiment provides a total internal reflection optical material feeding laser processing head with multi-beam internal coaxial powder (wire) feeding. Taking a four-beam (N=4) configuration as an example, its principle and process are described in detail. The total internal reflection optical material feeding laser processing head in this embodiment includes an optical fiber connector 1, an aspherical reflector 2, a plane reflector 3, a working surface 4, a transmission surface 5, and a wire (powder) feeding tube 6. The aspherical reflector 2 has a highly reflective coating on its reflective surface, a cylindrical structure, and a water-cooling channel to cool its reflective surface. The plane reflector 3 also has a water-cooling channel to cool its reflective surface. The plane reflector 3 has a circular hollow center to house the wire (powder) feeding tube 6, ensuring that the wire (powder) feeding tube 6 is coaxial with the laser beam.

[0077] The laser beam output from fiber optic connector 1 is reflected by aspherical mirror 2 and then split into four parts. The four aspherical reflection regions of aspherical mirror 2 each have a different surface shape; for example... Figure 2 The diagram shows the flowchart of the aspherical reflector surface design method. The specific process includes: determining the position and tilt angle of each reflective plane of the plane reflector; mapping the light spot at the working surface to N positions in space through each reflective plane; and the aspherical reflector dividing the incident laser beam into N parts and illuminating the corresponding N positions in space.

[0078] The tilt angle of any reflecting plane S' of the plane mirror is determined in the following way:

[0079] Based on the angle θ between the reflected ray from the preset reflecting plane S' and the axis of the feeding device, the direction of the reflected ray from the reflecting plane S' is obtained; wherein, θ is preferably arctan(d / L), d is the distance from the center point of the reflecting plane S' to the center of the plane mirror, and L is the distance from the center of the plane mirror to the working surface; preferably, the value of θ is in the range of 0.05 to 0.2 rad.

[0080] Based on the relationship that the angle between the straight line O1O2 and the incident ray of the reflecting plane S' is equal to θ, the direction of the incident ray of the reflecting plane S' is obtained;

[0081] Calculate the direction of the angle bisector between the incident ray and the reflected ray of the reflecting plane S', obtain the direction of the normal vector of the reflecting plane S', and thus obtain the tilt angle of the reflecting plane S'.

[0082] Wherein, the straight line O1O2 is the line connecting the center point O1 of the aspherical mirror and the center point O2 of the plane mirror.

[0083] like Figure 3 The diagram illustrates the method for determining the tilt angle of each reflecting plane of a plane mirror. O1, O2, and O3 are the center point of the aspherical mirror, the center point of the plane mirror, and the laser focusing point on the working surface, respectively. To ensure uniform laser incidence on the working surface, four points equidistant from O2 are selected, with point A being one of them. The incident ray O1A' exits as A'O3 after passing through the plane mirror, passing through point A. Furthermore, the angles between line O1A' and O1O2, and between A'O3 and O2O3, are equal. The angle bisector A'E of O1A' and O3A' is then taken; that is, line A'E is the normal to the reflecting plane of the plane mirror, thus allowing precise control of the tilt angle of that reflecting plane. The reflecting planes of the plane mirror can be integrated into a single process to ensure accuracy, reducing the alignment difficulty of the system and improving stability during use.

[0084] In this embodiment, the surface shape of each reflecting region of the aspherical mirror is a revolution ellipsoid;

[0085] Specifically, in this embodiment, the aspherical reflector can shape the point light source into four point spots, and then the planar reflector will focus them onto a single point on the working surface 4. The method for designing the rotating ellipsoidal surface shape is as follows: Figure 4 As shown, for any reflecting region S of an aspherical mirror, its surface shape satisfies the following: the ellipsoid obtained by rotating an ellipse with foci at points C and D around axis CD.

[0086] Wherein, point C is the location of the laser source of the incident laser; point D is the spatially symmetrical point of the laser focusing point on the working surface with respect to the reflection plane S' of the plane mirror; and the reflection plane S' is the reflection plane corresponding to the reflection region S.

[0087] like Figure 5 The diagram shows the light spots at various locations when the aspherical reflector has an ellipsoidal surface. After the incident laser beam passes through the aspherical reflector, it is first split into four discrete light spots. Then, after passing through the plane reflector, the beams merge into a point on the working surface.

[0088] like Figure 6 The diagram shows the structure of the protective mirror 8. Each working mirror surface is equipped with a protective mirror and a water-cooling device. The protective mirror is a hollow ring-shaped structure composed of N independently pluggable fan-shaped protective mirrors. The protective mirrors adopt a drawer-type split structure for easy and flexible disassembly, avoiding the difficulty of replacing the protective mirrors. Alternatively, the protective mirror can employ a double protective mirror structure. The outer protective mirror uses a drawer-type split structure for easy and flexible disassembly, while the inner ring-shaped protective mirror protects the optical path, preventing contamination of the optical path when replacing the protective mirror.

[0089] Example 2

[0090] This embodiment has the same structure as the total internal reflection optical material delivery laser processing head in Embodiment 1, the only difference being that the surface shape of each reflection area of ​​the aspherical mirror is a free-form surface.

[0091] The construction method of freeform surfaces mainly consists of two steps. The first step is to establish the energy mapping relationship between the light source and the target surface, and the second step is to construct the freeform surface of the reflector based on the mapping relationship.

[0092] Mapping methods can be established using the MA method, the supported quadratic surface method, or the variable separable mapping method, among others.

[0093] Methods for constructing freeform surfaces of mirrors based on mapping relationships include point-by-point iterative construction, orthogonal bidirectional iterative construction, expansion construction using seed curves, and least squares construction based on normal vectors.

[0094] Preferably, in this embodiment, the design method for the aspherical reflector surface type as a freeform surface specifically includes: for any reflecting region S:

[0095] S1. Initialize the surface shape of the reflection region S;

[0096] In this embodiment, the surface shape of the reflective region S is initialized as a plane with an inclination of 45°;

[0097] S2. Divide the cross-section of the incident laser source on the reflection region S into an equal-energy grid, thereby forming corresponding grid points on the reflection region S;

[0098] S3. Based on the relationship that the line vector connecting any two adjacent grid points in the reflection region S is perpendicular to the average value of the normal vectors at these two grid points, a set of linear equations is established to obtain the three-dimensional position data of each grid point in the reflection region S, so as to update the surface shape of the reflection region S. Here, the normal vector at any grid point in the reflection region S is the direction of the angle bisector between the incident ray and the reflected ray at that grid point. There is a one-to-one mapping relationship between a grid point in the reflection region S and a target grid point. The incident ray at a grid point in the reflection region S is reflected to the corresponding target grid point through that grid point. The target grid point is obtained by dividing the light spot on the working surface into grids according to preset requirements and spatially symmetrically dividing the grid points on the working surface about the plane mirror to obtain the corresponding target grid point.

[0099] S4. Repeat steps S2-S3 for iteration until the number of iterations reaches the preset number of iterations (2 in this embodiment) or the calculation result converges. At this time, the surface shape of the reflection region S is the surface shape of the desired reflection region S.

[0100] The energy distribution is the same in each region of the light source surface. The light spot on the working surface is divided into grids according to the preset requirements: the energy distribution of the flat-top light spot is uniform along the radial direction. If a flat-top light spot is required, the working surface can be divided into equal areas. The energy distribution of the concave-ring light spot is low in the middle and high on both sides along the radial direction. If a concave-ring light spot is required, the inner area of ​​the target surface can be divided more sparsely and the outer area can be divided more densely.

[0101] In this embodiment, the surface shape of the four reflecting regions of the aspherical mirror is designed based on the principle of ray mapping. Each reflecting region is a freeform surface, which allows for radial energy distribution design. It can be designed as a flat-topped light spot or a concave ring light spot to obtain a more uniform temperature field distribution. This will reduce spatter and achieve better processing results.

[0102] like Figure 7 The diagram shows the distribution of light spots at various locations to achieve a flat-top light spot. In this embodiment, the circular light spot is divided into four parts with equal energy distribution after passing through an aspherical reflector. Then, it is finally focused onto the working surface for processing by a combination of plane reflectors.

[0103] like Figure 8 The diagram shows the distribution of the circular light spot at various locations to achieve the concave light spot. The circular light spot is divided into four parts by a combination of aspherical mirrors, resulting in a concave light spot with energy distribution. Then, it is focused onto the working surface by a combination of plane mirrors for processing.

[0104] This invention simplifies optical system design and significantly reduces the number of optical components while ensuring beam splitting quality, and enhances the flexibility of the laser processing head. The advantages of the optical mechanism method proposed in this invention are:

[0105] (1) The aspherical mirror used in this invention is preferably machined by a high-precision lathe and adopts a reflective mirror surface, which can be used for processing applications of higher power lasers, greatly expanding the application field;

[0106] (2) The radial energy distribution of the light spot can be designed, and it can be designed as a flat-top light spot and an annular concave light spot to obtain a more uniform temperature field distribution, reduce splashing, and obtain better processing results.

[0107] (3) It can ensure that the wire or powder feeding tube does not need to be bent, and the wire (or powder) is fed into the center of the light spot in a coaxial manner, which improves the forming accuracy.

[0108] (4) The laser transmission process will not irradiate the wire feeder or powder feeder, ensuring the integrity of the laser spot, and there is no loss of the optical path due to the obstruction of the wire feeder or powder feeder.

[0109] (5) Aspherical mirrors and plane mirrors can adopt an integrated structure. The accuracy is ensured through processing, which reduces the alignment difficulty of the system and improves the stability during use.

[0110] (6) Dual protective lens structure: the outer protective lens adopts a drawer-type split structure, which is convenient and flexible to disassemble, and the inner ring protective lens protects the optical path. The optical path will not be contaminated when the protective lens is replaced.

[0111] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A total internal reflection type laser processing head for in-situ material delivery, characterized in that, include: Aspherical and planar mirrors are placed sequentially along the laser beam path. The aspherical mirror has N reflecting areas on its reflective surface; the planar mirror has N reflecting planes that correspond one-to-one with the N reflecting areas, and the planar mirror is hollow for placing the material feeding device. The surface shape of each reflection region of the aspherical mirror is a rotation ellipsoid or a freeform surface, which is used to split the incident laser emitted from the point source to obtain N laser beams, which are then incident on the corresponding reflection planes respectively. The tilt angles of each reflective plane of the plane mirror are different, and the angle between the reflected light from each reflective plane and the axis of the feeding device is the same. This is used to uniformly focus the reflected light from each reflective plane onto the working surface so as to process the material coaxially fed by the feeding device. Wherein, N≥2; the feeding device includes: a wire feeding device or a powder feeding device.

2. The laser processing head for in-light material delivery according to claim 1, characterized in that, The surface shape of each reflecting region of the aspherical mirror is a revolution ellipsoid. For any reflecting region S of the aspherical mirror, its surface shape satisfies the following: the ellipsoid obtained by rotating an ellipse with foci at points C and D around axis CD. Wherein, point C is the location of the laser source of the incident laser; point D is the spatially symmetrical point of the laser focusing point on the working surface with respect to the reflection plane S' of the plane mirror; and the reflection plane S' is the reflection plane corresponding to the reflection region S.

3. The laser processing head for in-light material delivery according to claim 1, characterized in that, The surface shape of each reflecting region of the aspherical mirror is a freeform surface; for any reflecting region S, its surface shape is determined in the following way: S1. Initialize the surface shape of the reflection region S; S2. Divide the cross-section of the incident laser source on the reflection region S into an equal-energy grid, thereby forming corresponding grid points on the reflection region S; S3. Based on the relationship that the line vector connecting any two adjacent grid points in the reflection region S is perpendicular to the average value of the normal vectors at these two grid points, a set of linear equations is established to obtain the three-dimensional position data of each grid point in the reflection region S, so as to update the surface shape of the reflection region S; wherein, the normal vector at any grid point in the reflection region S is the direction of the angle bisector of the incident ray and the reflected ray at that grid point; there is a one-to-one mapping relationship between the grid points on the reflection region S and the target grid points, and the incident ray at the grid point on the reflection region S is reflected to the corresponding target grid point after passing through the grid point on the reflection region S; the target grid point is obtained by dividing the light spot on the working surface into grids according to preset requirements, and spatially symmetrically dividing the grid points on the working surface about the plane mirror to obtain the corresponding target grid point; S4. Repeat steps S2-S3 for iteration until the number of iterations reaches the preset number of iterations or the calculation result converges. At this time, the surface shape of the reflection region S is the surface shape of the desired reflection region S.

4. The laser processing head for in-light material delivery according to claim 1, characterized in that, The tilt angle of any reflecting plane S' of the plane mirror is determined in the following way: The angle between the reflected light from the preset reflective plane S' and the axis of the feeding device. θ The direction of the reflected ray from the reflecting plane S' is obtained; Based on the angle between the straight line O1O2 and the incident light ray of the reflecting plane S' and θ By establishing the equality relationship, the direction of the incident ray on the reflecting plane S' can be obtained; Calculate the direction of the angle bisector between the incident ray and the reflected ray of the reflecting plane S' to obtain the direction of the normal vector of the reflecting plane S', and thus obtain the tilt angle of the reflecting plane S'. Wherein, the straight line O1O2 is the line connecting the center point O1 of the aspherical mirror and the center point O2 of the planar mirror.

5. The laser processing head for in-light material delivery according to any one of claims 1-4, characterized in that, The aspherical mirror has a high-reflectivity film coated on its reflective surface.

6. The laser processing head for in-light material delivery according to any one of claims 1-4, characterized in that, The aspherical mirror is equipped with a water-cooling channel.

7. The laser processing head for in-light material feeding according to any one of claims 1-4, characterized in that, The planar reflector is equipped with a water-cooling channel.

8. The laser processing head for in-light material feeding according to any one of claims 1-4, characterized in that, Also includes: A protective mirror is positioned along the optical path direction, behind the planar reflector and in front of the working surface.

9. The laser processing head for in-light material delivery according to claim 8, characterized in that, The protective mirror is a hollow ring-shaped protective mirror, which is composed of multiple independently pluggable fan-shaped protective mirrors. Alternatively, the protective mirror is a hollow double-layer protective mirror structure, including an inner protective mirror that is far from the working surface and an outer protective mirror that is close to the working surface; The inner protective mirror is a hollow ring-shaped protective mirror; the outer protective mirror is a hollow ring-shaped protective mirror, which is composed of multiple independently pluggable fan-shaped protective mirrors.

10. The laser processing head for in-light material delivery according to any one of claims 1-4, characterized in that, N=4。

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