Multifocal point ring spot generation system and laser welding method

Abstract

This invention provides a multi-focal point ring spot generation system and a laser welding method. [Solution] The system comprises annular light sources 11, a first collimator lens 12, an annular beam generation module 13, and a first reflector 14, arranged sequentially at intervals along a first linear direction; and point light sources 21, a second collimator lens 22, a first focusing lens 23, a multi-curvature hollow reflector 24, and a second focusing lens 25, arranged sequentially at intervals along a second linear direction. Through holes are provided in the centers of the multi-curvature hollow reflector and the second focusing lens through which the light beam emitted from the point light source passes, and the curvature of the mirror surface of the multi-curvature hollow reflector is adjustable. This solves the technical problems of conventional point-ring laser devices, such as soaring processing costs and reduced stability in deep welding, which are caused by structural constraints.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing, and particularly relates to a multi-focus point-ring spot generation system and a laser welding method.

Background Art

[0002] With the development of laser welding, the laser welding market has already become a highly competitive market, and the requirements for welding technology in the manufacturing industry are becoming even more stringent. Conventional welding methods (such as arc welding and ultrasonic welding) have limitations such as excessive temperature, large deformation, and unstable quality of the welded part during the welding process. On the other hand, in the process of laser welding, especially high-power welding, there is a problem that spatter is most likely to occur. The particles generated by spatter are likely to adhere to the molten pool and the workpiece surface, causing changes in surface roughness and damage to the base material. In addition, they pollute the clean environment inside the torch and also have an adverse effect on the lifespan of the optical lens.

[0003] In related technologies, a point-ring laser device can well solve the above problems. This device simultaneously emits two laser beams for the central part and the outer peripheral part from one laser oscillator, and forms a focused spot composed of a central point spot and an outer annular spot through a complex optical path system. During welding, the central point spot forms a molten pool, and at the same time, the outer ring laser rapidly heats and melts its peripheral part to prevent the generation of spatter.

[0004] However, conventional ring-shaped laser systems, such as IPG's AMB products and Raycus's ABP series, have the problem of high processing costs for laser welding due to the complex and expensive structure of their ring-shaped spot laser heads with external optical paths. Furthermore, the structure of these ring-shaped spot laser heads is constrained by the model specifications, and both the focused outer ring spot and the dot-shaped spot are focused on the same focal plane, resulting in a fixed spot shape. When laser welding thick workpieces at multiple penetration depths, if the dot-shaped spots reach different penetration depths, the outer ring spot experiences energy attenuation and insufficient penetration, reducing its heat-affected zone. This leads to uneven weld bead width depending on the workpiece thickness, degrading the stability of deep welding. [Overview of the project]

[0005] Embodiments of the present invention provide a multi-focus ring spot generation system and a laser welding method, which can solve the technical problems of increased processing costs and reduced stability of deep welding that arose in the prior art due to structural limitations of ring laser devices. The technical means are as follows.

[0006] As a first aspect, embodiments of the present invention provide a multifocal point ring spot generation system, which includes the following:

[0007] A first optical path unit comprising an annular light source arranged sequentially at intervals along a first linear direction, a first collimator lens, an annular beam generation module, and a first reflector, Second optical path unit: A second optical path unit comprising a point light source, a second collimator lens, a first focusing lens, a multi-curvature hollow reflector, and a second focusing lens arranged sequentially at intervals along a second linear direction, wherein through holes are provided in the centers of the multi-curvature hollow reflector and the second focusing lens through which the light beam emitted from the point light source passes, and the surface curvature of the multi-curvature hollow reflector is adjustable. The light beam emitted from the annular light source passes through the first collimator lens and the annular beam generation module, is then reflected sequentially by the first reflector and the multi-curvature hollow reflector, and is focused by the second focusing lens to form an annular spot. The light beam emitted from the point light source passes sequentially through the second collimator lens, the first focusing lens, the multi-curvature hollow reflector, and a through-hole provided in the center of the second focusing lens, and is then focused to form a point-shaped spot located inside the annular spot.

[0008] Preferably, a plurality of the first optical path units are provided, and the second optical path unit is provided with a plurality of multi-curvature hollow reflectors that correspond one-to-one with each of the plurality of first optical path units, and these plurality of multi-curvature hollow reflectors are arranged at intervals along the second linear direction.

[0009] Preferably, at least one of the plurality of first optical path units is provided with a dynamic change module, the dynamic change module is positioned between the first reflector and the multi-curvature hollow reflector provided in correspondence with the first optical path unit, and the dynamic change module includes two wedge prisms that are coaxially positioned in the direction of propagation of the light beam emitted from the annular light source and are rotatable in the axial direction, the refractive surfaces of the two wedge prisms facing each other.

[0010] Preferably, a plurality of the first optical path units are arranged at intervals along the first linear direction.

[0011] Preferably, an axicon lens is provided inside the annular beam generation module, arranged along the first linear direction.

[0012] Preferably, the axicon lens includes a negative axicon lens and a positive axicon lens that are arranged coaxially and spaced apart in the direction of propagation of the light beam emitted from the annular light source, and whose conical surfaces face each other.

[0013] Preferably, a biaxial galvanometer mirror is provided between the second collimator lens and the first focusing lens.

[0014] Preferably, the degree of collimation of the first collimator lens and the second collimator lens is adjustable.

[0015] As a second aspect, embodiments of the present invention provide a laser welding method realized based on the multifocal ring spot generation system described in the first aspect, The process involves passing the light beam emitted from the annular light source through the first collimator lens and the annular beam generation module, then sequentially reflecting it through the first reflector and the multi-curvature hollow reflector, and finally focusing it onto the surface of the workpiece with the second focusing lens to form an annular spot. The process involves sequentially passing a light beam emitted from the point light source through the second collimator lens, the first focusing lens, the multi-curvature hollow reflector, and a through hole provided in the center of the second focusing lens, and then focusing it onto the surface of the workpiece to form a point-shaped spot located inside the annular spot, The process includes adjusting the curvature of the multi-curvature hollow reflecting mirror to form an annular spot outside the focal plane of the point-like spot, and simultaneously forming an annular spot on a focal plane different from the point-like spot.

[0016] Preferably, the laser welding method includes the steps of providing a plurality of sets of the first optical path units, and providing a plurality of multi-curvature hollow reflectors within the second optical path unit, each corresponding one-to-one with the plurality of first optical path units, The method further includes the step of adjusting the focal plane of an annular spot formed by focusing light onto a workpiece with multiple sets of the first optical path units, thereby forming multiple annular spots on the outer periphery of a point-like spot, or forming multiple annular spots on a focal plane different from that of the point-like spot. [Effects of the Invention]

[0017] At least the following are some of the advantageous effects that can be obtained by the technical means provided in the embodiments of the present invention.

[0018] By employing the multi-focal point ring spot generation system according to an embodiment of the present invention, the first optical path unit and the second optical path unit are made to operate in coordination during the laser welding process, allowing control of the focal plane position of the ring spot formed by focusing along the optical path. This enables multi-focal relay with point spots, allowing welding at different focal planes, while maintaining heating and melting of the molten pool boundary at the focal plane of the point spots and suppressing spatter generation. Furthermore, even when processing workpieces of different thicknesses, the weld bead width at each penetration depth position can be uniformly controlled. The overall optical path structure is simple, effectively solving the technical problems of increased processing costs and reduced stability of deep welding caused by the structural constraints of conventional point ring laser devices. [Brief explanation of the drawing]

[0019] To more clearly explain the technical means according to the embodiments of the present invention, the drawings used in the description of the embodiments are briefly introduced below. As is clear, the drawings shown below represent only a few embodiments of the present invention, and those skilled in the art can easily create other drawings based on these without requiring any creative effort.

[0020] [Figure 1] This is a schematic diagram of the configuration of a multi-focus ring spot generation system according to an embodiment of the present invention. [Figure 2] This is a schematic diagram of the configuration of another multifocal point ring spot generation system according to an embodiment of the present invention. [Figure 3] This is a schematic diagram of the configuration of a dynamic change module according to an embodiment of the present invention. [Figure 4] This is a schematic diagram of the optical path of a two-axis galvanometer mirror in a module according to an embodiment of the present invention. [Figure 5] This is a flowchart of a laser welding method according to an embodiment of the present invention. [Figure 6]It is a schematic diagram of a kind of workpiece processing according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0021] To make the object, technical means and advantageous effects of the present invention clearer, the embodiments of the present invention will be described in more detail below with reference to the accompanying drawings.

[0022] FIG. 1 is a schematic configuration diagram of a kind of multi-focus point ring spot generation system according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of another kind of multi-focus point ring spot generation system according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram of a dynamic change module according to an embodiment of the present invention. FIG. 4 is a schematic optical path diagram of a two-axis galvanometer mirror in a module according to an embodiment of the present invention. As shown in FIGS. 1 to 4, the embodiment of the present invention provides a multi-focus point ring spot generation system, and the system includes a first optical path unit 1 and a second optical path unit 2.

[0023] Among them, the first optical path unit 1 includes an annular light source 11, a first collimator lens 12, an annular beam generation module 13, and a first mirror 14 that are arranged in sequence at intervals along the first straight line direction.

[0024] The second optical path unit 2 includes a point light source 21, a second collimator lens 22, a first condenser lens 23, a multi-curvature hollow mirror 24, and a second condenser lens 25 that are arranged in sequence at intervals along the second straight line direction. Through holes through which the light beam emitted from the point light source 21 passes are provided at the central parts of the multi-curvature hollow mirror 24 and the second condenser lens 25, and the mirror curvature of the multi-curvature hollow mirror 24 is adjustable.

[0025] The light beam emitted from the annular light source 11 passes through the first collimator lens 12 and the annular beam generation module 13, is then reflected sequentially by the first reflector 14 and the multi-curvature hollow reflector 24, and is focused by the second focusing lens 25 to form an annular spot. The light beam emitted from the point light source 21 passes sequentially through the second collimator lens 22, the first focusing lens 23, the multi-curvature hollow reflector 24, and the through-hole provided in the center of the second focusing lens 25, and is then focused to form a point-like spot located inside the annular spot.

[0026] In embodiments of the present invention, when laser welding a workpiece, the first optical path unit 1 and the second optical path unit 2 operate in coordination. The light beam emitted from the point light source 21 passes through the second collimator lens 22 to become parallel light, is then focused by the first focusing lens 23, and then sequentially passes through the multi-curvature hollow reflector 24 and the through-hole provided in the center of the second focusing lens 25 before being focused on the workpiece surface to form a point-like spot. Simultaneously, the light beam emitted from the annular light source 11 passes through the first collimator lens 12 to become parallel light, and then forms an annular beam via the annular beam generation module 13. Specifically, the annular beam generation module 13 can be configured in the form of an optical fiber circulator, a DOE (Diffractive Optical Element), or an axicon lens. The optical fiber circulator converts the ground mode to annular mode using a fiber Bragg grating or tapered coupler, but its ring diameter is fixed by the fiber parameters and cannot be dynamically adjusted. A Gaussian beam can generate an annular optical field through diffraction by a DOE phase plate, and its ring diameter is dynamically adjustable, but real-time tuning requires a costly spatial light modulator. Parallel light can generate a Bessel beam via an axicon lens, forming an annular beam, which has the advantages of continuously adjustable ring diameter, a long non-diffraction distance, and the ability to handle ultra-high power. Considering cost and installation difficulty, the embodiment of the present invention employs a configuration in which collimated parallel light and an axicon lens 131 provided in the annular beam generation module 13 are combined to generate an annular beam. Subsequently, the light beam is sequentially reflected by the mirror surfaces on the outer periphery of the through-holes of the first reflector 14 and the multi-curvature hollow reflector 24, and finally focused by the mirror surface on the outer periphery of the through-hole of the second focusing lens 25, forming an annular spot on the outer periphery of a point-like spot on the workpiece. During welding, the central point-like spot forms a molten pool, while the annular spot on the outer periphery rapidly heats and melts its edge, preventing spatter generation.

[0027] Furthermore, by dynamically controlling the curvature of the multi-curvature hollow reflecting mirror 24 and converting drive signals such as electricity, magnetism, and atmospheric pressure into precise minute displacements of the mirror surface, the phase of the reflected or transmitted light is modulated, and uniform pressure is applied overall to achieve axial focus adjustment of the annular spot. As the curvature increases, the divergence of the light beam intensifies, and the focal point after passing through the second focusing lens 25 approaches the second focusing lens 25. On the other hand, as the curvature decreases, the convergence of the light beam intensifies, and the focal point after passing through the focusing lens moves away from the second focusing lens 25. When an annular spot and a point spot are located on the same focal plane, by adjusting the curvature of the multi-curvature hollow reflecting mirror 24 to decrease the surface curvature, the focal plane of the annular spot is moved downward, forming a pre-melting region of the annular spot at a deeper welding depth in the workpiece, thereby expanding the heat-affected zone. At the focal plane where the point spot is located, the annular beam can heat and melt the boundary of the molten pool formed by the point spot from the outer periphery, preventing spatter and oxidation.

[0028] By employing the multi-focal point ring spot generation system according to an embodiment of the present invention, the first optical path unit 1 and the second optical path unit 2 are made to operate in coordination during the laser welding process, and the focal plane position of the ring spot formed by focusing can be controlled on the optical path. This realizes multi-focal relay with point-like spots, enabling welding at different focal planes, while maintaining heating and melting of the molten pool boundary at the focal plane of the point-like spots and suppressing spatter generation. Furthermore, even when processing workpieces of different thicknesses, the weld bead width at each penetration depth position can be uniformly controlled. The overall optical path structure is simple, and it can effectively solve the technical problems of increased processing costs and reduced stability of deep welding caused by the structural constraints of conventional point-ring laser devices.

[0029] Preferably, multiple first optical path units 1 are provided, and within the second optical path unit 2, multiple multi-curvature hollow reflectors 24 are provided, each corresponding one-to-one with the multiple first optical path units 1, and the multiple multi-curvature hollow reflectors 24 are spaced apart along the second linear direction. Exemplarily, in an embodiment of the present invention, two first optical path units 1 are provided, and they are spaced apart along the first linear direction, i.e., the direction of light emission from the annular light source 11. Both units are located to the side of the second optical path unit 2 which includes the point light source 21, and this same-side arrangement makes it easy to arrange the multi-curvature hollow reflectors 24 within the second optical path unit 2 in the same direction on the optical path of the point light source 21. Furthermore, the extension length of the second optical path unit 2 in the optical path direction can be made to the maximum extent, and the overall space occupied by the system can be reduced. In the two second optical path units 2, the annular light reflected by the first reflectors 14 is arranged to face the same side and is reflected by the corresponding multi-curvature hollow reflectors 24. As a result, the light is focused through the second focusing lens 25, forming an annular spot. By providing two sets of first optical path units 2, two independent annular spots can be formed on the surface of the workpiece to be welded, and / or multiple annular spots can be formed on a focal plane different from that of the point spot. Depending on the actual processing specifications of the workpiece, the two first optical path units 1 can be operated individually or simultaneously. For example, when the two first optical path units 1 are operated simultaneously, two annular spots of different diameters can be formed outside the point spot. For example, the diameter of the inner first annular spot located on the outer circumference of the point spot can be set to 2 to 3 times the diameter of the point spot and can be used to form the boundary of the molten pool. On the other hand, the diameter of the second outer annular spot located outside of it can be set to 1.5 to 2 times the diameter of the inner annular spot and can be used to suppress spatter and oxidation. Another implementation involves adaptively adjusting the surface curvature of the multi-curvature hollow reflector 24 in the second optical path unit 2 to independently adjust the focal planes of the two annular spots, thereby forming a combination of a point-like spot and a multi-focal annular spot and achieving concentric coupling of a composite multi-focal beam.This enables simultaneous welding at different focal planes, further improving the ability to control the melting width of the weld bead. For example, a dot spot operates by focusing on the workpiece surface or slightly below the workpiece surface during operation. The focal plane of an inner annular spot located on the outer periphery of the dot spot can be set slightly deeper than the focal plane of the dot spot, thereby forming a preheating region below. The focal plane of the outer annular spot of the inner annular spot can be set even deeper than the inner annular spot and is used to control the premelting region or heat-affected zone.

[0030] Preferably, at least one of the multiple first optical path units 1 is provided with a dynamic change module 3, which is positioned between a first reflector 14 and a multi-curvature hollow reflector 24 provided in correspondence with the first optical path unit 1. The dynamic change module 3 includes two wedge prisms 31 that are coaxially positioned in the direction of propagation of the light beam emitted from the annular light source 11 and are rotatable in the axial direction, with the refractive surfaces of the two wedge prisms 31 facing each other. Exemplarily, in an embodiment of the present invention, a dynamic change module 3 is additionally installed in the first optical path unit 1, with two wedge prisms arranged therein, and corresponding motors and rotors provided to control the rotation of the two wedge prisms 31. By rotating the two wedge prisms 31 in the same direction and at the same speed, their refractive vectors are combined to have a constant deflection angle. As a result, the annular beam is scanned to trace a circular orbit on the focal plane. By relatively controlling the initial phase angle difference between the two wedge prisms, the center position of this circular motion can be fixed or moved, enabling the position of the optical spot to be shifted after focusing. During the rotation adjustment process, the magnitude of the combined refraction angle can be adjusted by changing the rotation speed ratio or relative angle of the two wedge prisms 31, thereby enabling dynamic expansion or contraction of the radius of the annular spot. Conventional point-ring laser devices have the drawback that the generated point-like spot and annular spot only oscillate synchronously and cannot be adjusted independently for oscillation or spot shape, but this is improved in the present invention.

[0031] Preferably, the axicon lens 131 includes a negative axicon lens 131a and a positive axicon lens 131b, which are arranged coaxially and spaced apart in the direction of propagation of the light beam emitted from the annular light source 11, and whose conical surfaces face each other. Exemplarily, referring to Figure 2, an embodiment of the present invention may employ an integrated positive and negative axicon lens annular beam generation module 13, composed of a negative axicon lens 131a and a positive axicon lens 131b. When collimated parallel light passes through the annular beam generation module 13, the light rays first pass through the negative axicon lens 131a to form a diverging annular spot, and then pass through the positive axicon lens 131b to recombine the diverging annular beam with the parallel light, thereby adjusting and controlling the ring width and diameter of the annular light. In this way, by combining reflection by the multi-curvature hollow reflector 24 and focusing by the second focusing lens 25, an annular spot of a desired size can be formed. Furthermore, by changing the apex angle, spacing, and size of the light beam passing through the negative axicon lens 131a and positive axicon lens 131b, the final size of the annular spot can be further adjusted, thereby improving processing adaptability.

[0032] Preferably, a biaxial galvanometer mirror 4 is provided between the second collimator lens 22 and the first focusing lens 23. Exemplarily, within the second optical path unit, a biaxial galvanometer mirror 4 is provided between the second collimator lens 22 and the first focusing lens 23, and the optical beam is arbitrarily deflected in a two-dimensional plane by the coordinated scanning operation of two high-speed galvanometer scanners. By controlling the deflection angle and direction of the optical beam by mechanical vibration, the laser beam emitted from the point source 21 can be precisely controlled, and the focusing point of the point spot can be dynamically moved.

[0033] Preferably, the degree of collimation of the first collimator lens 12 and the second collimator lens is adjustable. Exemplaryly, in embodiments of the present invention, the first collimator lens 12 and the second collimator lens 22 may be collimated at the same focal length or at different focal lengths to adjust the optical beam diameter of the annular light source 11 and the point light source 21. The laser output can also be appropriately selected and combined according to the processing conditions. This adjustment is made possible by modularizing the corresponding positions of the first optical path unit 1 and the second optical path unit 2, allowing for attachment, detachment, and replacement via external operation, and enabling precise control of the focal position of the final formed spot and various parameters. This further improves the flexibility and adaptability of the system.

[0034] Exemplary, in an embodiment of the present invention, the multi-curvature hollow reflecting mirror 24 is a fully water-cooled metal mirror, and multiple cooling water channels are provided inside the mirror body. This allows for the circulation of cooling water, and by maintaining a constant temperature across the entire mirror surface during processing, it is possible to achieve reflection of a higher-power light beam.

[0035] Figure 5 shows a flowchart of a laser welding method according to an embodiment of the present invention. As shown in Figure 5, an embodiment of the present invention further provides a laser welding method implemented based on the multi-focus ring spot generation system shown in Figures 1 to 4. The method includes the following steps.

[0036] S1: The light beam emitted from the annular light source 11 passes through the first collimator lens 12 and the annular beam generation module 13, is then reflected sequentially by the first reflector 14 and the multi-curvature hollow reflector 24, and is focused onto the workpiece surface by the second focusing lens 25 to form an annular spot.

[0037] S2: The light beam emitted from the point light source 21 is passed sequentially through the second collimator lens 22, the first focusing lens 23, the multi-curvature hollow reflector 24, and the through hole provided in the center of the second focusing lens 25, and then focused onto the workpiece surface to form a point-shaped spot located inside the spot.

[0038] S3: The curvature of the multi-curvature hollow reflecting mirror 24 is adjusted to form an annular spot outside the focal plane of the point spot, and at the same time, an annular spot is also formed on a different focal plane from the point spot.

[0039] By employing the multi-focal point ring spot generation system according to an embodiment of the present invention and performing the laser welding method described above, the first optical path unit 1 and the second optical path unit 2 are made to operate in coordination during the laser welding process, and the focal plane position of the ring spot formed by focusing can be controlled on the optical path. This realizes multi-focal relay with point spots, enabling welding at different focal planes, while maintaining heating and melting of the molten pool boundary at the focal plane of the point spots and suppressing spatter generation. Furthermore, even when processing workpieces of different thicknesses, the weld bead width at each penetration depth position can be uniformly controlled. The overall optical path structure is simple, and it can effectively solve the technical problems of increased processing costs and reduced stability of deep welding caused by the structural constraints of conventional point ring laser devices.

[0040] S4: Multiple sets of first optical path units 1 are provided, and within the second optical path unit 2, multiple multi-curvature hollow reflectors 24 are provided, each corresponding to one of the multiple first optical path units 1.

[0041] S5: By adjusting the focal plane of the annular spot formed on the workpiece by focusing light with multiple sets of first optical path units 1, multiple annular spots are formed on the outer periphery of a point-like spot, or multiple annular spots are formed on a focal plane different from that of the point-like spot.

[0042] Furthermore, by providing multiple sets of first optical path units 1 and adaptively adjusting the surface curvature of the multi-curvature hollow reflector 24 in the second optical path unit 2, the focal planes of the two annular spots are adjusted, forming a combination of a point spot and a multi-focal annular spot, thereby achieving concentric coupling of a composite multi-focal beam. This enables simultaneous welding at different focal planes and further improves the ability to control the melting width of the weld bead. For example, the point spot operates by focusing on the workpiece surface or slightly below the workpiece surface during operation. The focal plane of the inner annular spot located on the outer circumference of the point spot can be set slightly deeper than the focal plane of the point spot, thereby forming a preheating region below. The focal plane of the outer annular spot of the inner annular spot is set even deeper than the inner annular spot and is used to control the pre-melting region or heat-affected zone.

[0043] Specifically, as a result of numerous processing experiments conducted by the applicant, a threshold control parameter for the distance between the focal planes of the annular spot and the point-shaped spot formed by the two first optical path units 1 was derived for workpieces of different thicknesses. By setting the spacing between the spot focal planes by referring to this threshold range, an optimal welding effect can be obtained.

[0044] Referring to the explanation above, let Z1 be the focal depth of the point-like spot on the workpiece machining surface, Z2 be the inner annular spot, and Z3 be the outer annular spot. The axial distance between the annular spot and the point-like spot is defined as ΔZ1=|Z2-Z1| and ΔZ2=|Z3-Z1|. These satisfy the following threshold relationship.

[0045] JPEG0007840604000002.jpg19170

[0046] JPEG0007840604000003.jpg19170

[0047] JPEG0007840604000004.jpg19170

[0048] Furthermore, depending on the properties of the workpiece material to be welded, for materials with high thermal conductivity (e.g., aluminum), the axial distance between point-like spots and annular spots needs to be set smaller, while for materials with low thermal conductivity (e.g., titanium), the distance can be set to a moderately larger value.

[0049] Furthermore, as a feasible configuration, the first reflector 14 in the first optical path unit 1 and the multi-curvature hollow reflector 24 provided in the second optical path unit 2 corresponding to the first reflector 14 may be configured to be synchronously adjusted in the second linear direction (i.e., the vertical direction) by an external drive structure, such as a motor drive. This allows for adjustment of the width of the annular beam reflected by the outer peripheral mirror surface of the incident-side through-hole of the second focusing lens 25, and ultimately allows for real-time adjustment of the focal plane of the annular spot focused at the workpiece position.

[0050] In response to this, the first focusing lens 23 within the second optical path unit 2 may also be configured to be able to adjust its position in the second linear direction by motor drive. This allows for real-time adjustment of the focal plane of the point spot focused at the workpiece position.

[0051] Figure 6 is a schematic diagram of a workpiece processing method according to an embodiment of the present invention. Referring to Figure 6, when welding a workpiece with gradually changing thickness using this multi-focal-point ring spot generation system, the first section 51 of the striped workpiece 5 is relatively thin, and after welding is performed from one end along the horizontal direction, the thickness increases in the portion that goes through the transition section 52 to the second section 53. At the start of processing, two sets of first optical path units 1 and one set of second optical path units 2 form a point-like spot, an inner ring spot, and an outer ring spot located outside of it, respectively, on the workpiece. The focal planes of the inner ring spot and the outer ring spot are set to be gradually deeper than the focal plane of the point-like spot, and the distance between the three focal planes is kept constant. This achieves a uniform distribution in the thickness direction of the first section 51. Welding is performed along the horizontal direction, and as the light spot moves to the transition section 52, the first focusing lens 23 and the two sets of first optical path reflectors 14 and multi-curvature hollow reflectors 24 are raised at a set speed, and their movement is stopped when they reach the second section 53. This maintains a uniform distribution of focal planes in the thickness direction for the point spot, inner annular spot, and outer annular spot even during welding in the second section 53, enabling real-time control of the pre-melting region or heat-affected zone and ensuring the stability of deep welding.

[0052] Unless otherwise specified, technical or scientific terms used herein have the general meanings that are ordinarily understood by those skilled in the art in which the present invention pertains. Terms such as “first,” “second,” etc., used in the patent application specification and claims of the present invention do not indicate order, quantity, or importance, but are used simply to distinguish different components. Similarly, terms such as “one,” or “single,” do not imply a quantitative limitation, but indicate the presence of at least one. Terms such as “include,” or “inclusive,” mean that the element or object described before “include,” or “inclusive,” includes the elements or objects listed after “include,” or “inclusive,” and their equivalents, but do not exclude other elements or objects. Terms such as “connect,” or “link,” mean that they are not limited to physical or mechanical connections, but also include electrical connections, and may be direct or indirect. Terms such as “up,” “down,” “left,” and “right” mean that they merely indicate relative positions, and that if the absolute position of the object described changes, its relative position may change accordingly.

[0053] The foregoing description represents only optional embodiments of the present invention and does not limit it. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall all be within the scope of protection of the present invention. [Explanation of symbols]

[0054] 1. First optical path unit 2-Second Optical Path Unit 3. Dynamic Change Module 4-2 axis galvanometer mirror 5-Striped workpiece 11-Annular light source 12-1st collimator lens 13. Circular Beam Generation Module 14-1st reflector 21-point light source 22-Second Collimator Lens 23-First condensing lens 24-Multi-curvature hollow reflector 25 - Second focusing lens 31-Wedge Prism 51 - Section 1 52-Transition Section 53 - Section 2 131-Axicon Lens 131a - Negative Axicon Lens 131b - Positive Axicon Lens

Claims

1. A multifocal point ring spot generation system, A first optical path unit (1) includes an annular light source (11) arranged sequentially at intervals along a first linear direction, a first collimator lens (12), an annular beam generation module (13), and a first reflector (14). A second optical path unit (2) comprises point light sources (21) arranged sequentially at intervals along a second linear direction, a second collimator lens (22), a first focusing lens (23), a multi-curvature hollow reflector (24), and a second focusing lens (25), wherein through holes are provided in the centers of the multi-curvature hollow reflector (24) and the second focusing lens (25) for the light beam emitted from the point light source (21) to pass through, and the surface curvature of the multi-curvature hollow reflector (24) is adjustable. The light beam emitted from the annular light source (11) passes through the first collimator lens (12) and the annular beam generation module (13), is then reflected sequentially by the first reflector (14) and the multi-curvature hollow reflector (24), and is focused by the second focusing lens (25) to form an annular spot. The light beam emitted from the point light source (21) is focused after passing through the second collimator lens (22), the first focusing lens (23), the multi-curvature hollow reflector (24), and the through hole provided in the center of the second focusing lens (25), forming a point-shaped spot located inside the annular spot. A multifocal point ring spot generation system characterized by the following features.

2. Multiple first optical path units (1) are provided, and the second optical path unit (2) is provided with multiple multi-curvature hollow reflectors (24) that correspond one-to-one with each of the multiple first optical path units (1), and the multiple multi-curvature hollow reflectors (24) are arranged at intervals along the second linear direction. The multifocal point ring spot generation system according to feature 1.

3. A dynamic change module (3) is provided in at least one of the plurality of first optical path units (1), and the dynamic change module (3) is positioned between the first reflector (14) and the multi-curvature hollow reflector (24) provided in correspondence with the first optical path unit (1), and the dynamic change module (3) includes two wedge prisms (31) that are coaxially positioned in the direction of propagation of the light beam emitted from the annular light source (11) and are rotatable in the axial direction, and the refractive surfaces of the two wedge prisms (31) are positioned facing each other. The multifocal point ring spot generation system according to feature 2.

4. Multiple first optical path units (1) are arranged at intervals along the first linear direction. The multifocal point ring spot generation system according to feature 2.

5. An axicon lens (131) is provided inside the annular beam generation module (13) and is arranged along the first linear direction. The multifocal point ring spot generation system according to feature 1.

6. The axicon lens (131) includes a negative axicon lens (131a) and a positive axicon lens (131b) which are arranged coaxially and spaced apart in the direction of propagation of the light beam emitted from the annular light source (11), and whose conical surfaces face each other. The multifocal point ring spot generation system according to feature 5.

7. A biaxial galvanometer mirror (4) is provided between the second collimator lens (22) and the first focusing lens (23). A multifocal point ring spot generation system according to any one of claims 1 to 6.

8. The degree of collimation of the first collimator lens (12) and the second collimator lens (22) is adjustable. A multifocal point ring spot generation system according to any one of claims 1 to 6.

9. A laser welding method, The process involves passing the light beam emitted from the annular light source (11) through the first collimator lens (12) and the annular beam generation module (13), then sequentially reflecting it through the first reflector (14) and the multi-curvature hollow reflector (24), and finally focusing it onto the surface of the workpiece with the second focusing lens (25) to form an annular spot. The process involves passing the light beam emitted from the point light source (21) sequentially through the second collimator lens (22), the first focusing lens (23), the multi-curvature hollow reflector (24), and a through hole provided in the center of the second focusing lens (25), and then focusing it onto the surface of the workpiece to form a point-shaped spot located inside the annular spot, The process includes adjusting the surface curvature of the multi-curvature hollow reflecting mirror (24) to form an annular spot outside the focal plane of the point-like spot, and simultaneously forming an annular spot on a focal plane different from the point-like spot. A laser welding method carried out based on a multifocal point ring spot generation system according to any one of claims 1 to 6.

10. The process involves providing multiple sets of the first optical path units (1), and providing multiple multi-curvature hollow reflectors (24) within the second optical path unit (2), each corresponding to one of the multiple first optical path units (1). The process includes adjusting the focal plane of an annular spot formed by focusing light onto a workpiece using multiple sets of the first optical path units (1), thereby forming multiple annular spots on the outer periphery of a point-like spot, or forming multiple annular spots on a focal plane different from that of the point-like spot. The laser welding method according to feature 9.

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