Laser processing device and laser processing method
The laser processing apparatus and method address the challenge of precise alignment by using annular and surrounding laser beams with a prism and cylindrical lens, achieving consistent, high-quality welding with simplified adjustments and reduced spatter.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
- Filing Date
- 2025-11-27
- Publication Date
- 2026-06-04
AI Technical Summary
Conventional laser processing methods require precise adjustments of the distance between prisms and cylindrical lenses, and optical axis alignment to achieve uniform beam intensity distribution, which is challenging when workpiece materials and thickness vary, leading to issues like weld mark size changes and reduced intensity at the center.
A laser processing apparatus and method using a laser emission unit that emits annular and surrounding laser beams, combined with a prism for beam inversion and a cylindrical lens for focusing, allowing independent output adjustments without precise alignment, resulting in a flattened beam cross-section for improved welding.
This approach simplifies the adjustment process, reduces spatter generation, and ensures consistent, high-quality welding even with varying workpiece conditions, enhancing production efficiency.
Smart Images
Figure JP2025041433_04062026_PF_FP_ABST
Abstract
Description
Laser Processing Apparatus and Laser Processing Method Cross - reference to Related Applications
[0001] This disclosure claims the benefit of priority of Japanese Patent Application No. 2024 - 208453, filed on November 29, 2024, with the Japan Patent Office, and the entire contents of the said patent application are incorporated herein by reference.
[0002] This disclosure relates to a laser processing apparatus and a laser processing method.
[0003] Conventionally, when irradiating a workpiece with a linear (rectangular) laser, in order to uniformly control the beam intensity distribution, before irradiating the laser to the workpiece, (A) the laser is split into two by passing it through a prism, and the split lasers are overlapped and interfered with each other, and (B) the process of condensing the laser by passing it through a cylindrical lens is made to pass through the laser. This method is known (see, for example, Patent Document 1). In this case, a Gaussian beam is used as the laser.
[0004] Japanese Patent Laid - Open No. 5 - 171422
[0005] By changing the distance between the prism and the cylindrical lens and changing the degree of overlap of the split lasers, the beam intensity distribution can be adjusted, but at the same time, the size of the weld mark also changes. Especially when the workpiece material and thickness change, fine adjustment is difficult. Also, when the beam profile is inverted with a prism, the beam intensity at the center becomes small, resulting in a weld mark like a gourd. To obtain a rectangular weld mark, precise optical axis adjustment (plane / vertical direction) of the prism becomes necessary.
[0006] One aspect of this disclosure relates to a laser processing apparatus. The laser processing apparatus includes a laser emission unit that emits a first laser beam having an annular beam cross-section and a second laser beam having a beam cross-section surrounded by the first laser beam, a prism that transmits and splits the first and second laser beams to invert the beam profile, and a cylindrical lens that transmits and focuses the split first and second laser beams, thereby emitting an emitted beam having a flattened beam cross-section.
[0007] Another aspect of this disclosure relates to a laser processing method. This laser processing method includes a laser emission step of emitting a first laser beam having an annular beam cross-section and a second laser beam having a beam cross-section surrounded by the first laser beam; a splitting and inversion step of passing the first laser beam and the second laser beam through a prism to split them and invert the beam profile; a focusing step of passing the split first laser beam and the second laser beam through a cylindrical lens to focus them and emit an emitted beam having a flattened beam cross-section; and a welding step of irradiating a first workpiece and a second workpiece with the emitted beam from the first workpiece side to weld the first workpiece and the second workpiece together.
[0008] The laser processing apparatus and laser processing method described herein eliminate the need for precise adjustments of the distance between the prism and the cylindrical lens, the optical axis of the prism, etc., in order to emit light having a flattened beam cross-section. Novel features of the present invention are described in the appended claims, but the present invention, both in terms of its structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in reference to the drawings.
[0009] This is a schematic diagram illustrating the configuration of a laser processing apparatus 1 according to one embodiment of the present disclosure. This is a schematic diagram illustrating the configuration of a laser emission unit 10 provided in the laser processing apparatus 1. (a) is a schematic diagram illustrating the cross-sections of the first laser beam L1 and the second laser beam L2 emitted from the laser emission unit 10. (b) is a schematic diagram illustrating the intensity distribution of the first laser beam L1 and the second laser beam L2. (a) is a schematic diagram illustrating a cross-section of the emitted light Lout emitted from the laser processing apparatus 1. (b) is a schematic diagram illustrating its intensity distribution. This is an explanatory diagram illustrating a simplified, flattened beam cross-section of the emitted light Lout. This is an explanatory diagram illustrating a welding process in a laser processing method according to one embodiment of the present disclosure.
[0010] The laser processing apparatus and laser processing method related to this disclosure will be described below with examples. However, this disclosure is not limited to the examples described below. In the following description, specific numerical values and materials may be given as examples, but other numerical values and materials may be applied as long as the effects of this disclosure are achieved.
[0011] 1. Laser Processing Apparatus The laser processing apparatus according to this disclosure comprises a laser emission unit, a prism, and a cylindrical lens.
[0012] 1.1 Laser Emitting Section The laser emission section emits a first laser beam with an annular cross-section and a second laser beam with a cross-section surrounded by the first laser beam. In other words, the laser emission section emits a so-called ring beam, consisting of a core and a ring surrounding it, rather than the Gaussian beam commonly used. The output of the core and ring sections can be changed independently or their output ratio can be changed, but details will be described later.
[0013] The laser emission unit includes a laser light source that emits laser light and a laser beam forming unit that forms a first laser beam and a second laser beam from the laser light emitted from the laser light source. Examples of the laser light source include, but are not limited to, semiconductor lasers such as laser diodes, solid-state lasers, or gas lasers. A separate laser light source may be provided for each of the first and second laser beams, but this configuration is not limited to that. The laser beam forming unit is an optical system that changes the shape and intensity distribution of the incident laser light to a desired profile. The laser beam forming unit is composed of, for example, a refractive optical system, but is not limited to that. The laser beam forming unit is sometimes referred to as a beam shaper.
[0014] The wavelengths of the first laser beam and the second laser beam are preferably, for example, 100 nm or more and 2000 nm or less.
[0015] 1.2 Prisms A prism splits the beam profile by transmitting the first and second laser beams, thereby inverting the beam profile. A prism is an optical element that disperses, refracts, totally reflects, and birefrs light. Prisms are polyhedra made of a transparent medium such as glass or quartz, and at least one pair of their faces are not parallel; they are generally convex, and often triangular prism-shaped.
[0016] The prism has a convex surface and a flat surface. Either surface can be used to receive the first and second laser beams, but it is preferable to receive them on the convex surface to minimize the effects of reflection. It is also preferable to apply an anti-reflective coating to both the convex and flat surfaces of the prism.
[0017] Specifically, a prism can be one that divides the beam into two by transmitting the first and second laser beams, i.e., a triangular prism shape. However, the number of divisions by the prism is not limited to two.
[0018] 1.3 Cylindrical Lenses Cylindrical lenses focus the divided first and second laser beams by transmitting them through them. A cylindrical lens is a lens shaped like a section cut out of a cylinder. Examples of cylindrical lenses include cylindrical lenses and cylindrical lenses, but are not limited to these. For example, when a laser beam is incident on the curved surface of a cylindrical lens, the diameter of the original laser beam is maintained in the direction without curvature, while the laser beam shrinks in the direction with curvature. As a result, a linear or narrow strip-shaped laser beam is emitted from the cylindrical lens.
[0019] With the configuration described above, this laser processing device emits light having a flattened beam cross-section. Because the beam profile is inverted by a prism, the first laser beam, which has an annular cross-section, corresponds to the center of the emitted light, and the second laser beam corresponds to both ends of the emitted light. This makes it possible to make the flattened beam cross-section closer to a rectangle. As a result, the generation of spatter, which is a problem in welding methods that scan the area to be welded with a narrow laser beam or methods that irradiate with a circular beam, can be greatly suppressed, making it possible to perform good welding.
[0020] For example, when welding a current collector plate or battery can to the other end of a lead, one end of which is connected to a battery electrode, it is necessary to reliably prevent spatter. If spatter occurs, an internal short circuit may occur in the battery electrode body, potentially leading to product defects. On the other hand, the beam profile that allows for good welding can fluctuate from time to time due to variations in component tolerances and conditions. Using the laser processing apparatus according to this disclosure, it becomes possible to consistently form a good, flat-shaped weld even under such limitations. Therefore, the production efficiency of batteries is significantly improved.
[0021] Here, assuming that the beam cross-section is a flattened shape with a horizontally elongated rectangle and semicircular ends, its perimeter can be calculated as 2(L-W) + πW, where L is the major axis and W is the minor axis (equal to the diameters of the semicircles at both ends). If PL1 is the perimeter of the beam cross-section actually emitted from the laser processing device, then the ratio of the perimeter PL1 to "2(L-W) + πW" is preferably between 1 and 2. In this case, the perimeter PL1 of the beam cross-section can be approximated as a rectangle. In a flattened weld mark M that can be approximated as a rectangle, it is easier to uniformly control the melting state of the workpiece, easier to prevent spatter generation, and better welding is possible. On the other hand, as the weld mark becomes larger and its shape approaches a circle, excessive melting tends to occur in the central region, which is difficult to cool. Therefore, it becomes difficult to control the melting state of the workpiece, and good welding becomes difficult.
[0022] 1.4 Output Adjustment Section The laser processing apparatus according to this disclosure further comprises an output adjustment section. This output adjustment section changes the output ratio of the first laser beam and the second laser beam, or the output of at least one of the first laser beam and the second laser beam. This makes it possible to easily fine-tune the intensity distribution within the beam cross-section of the emitted light from the laser processing apparatus by changing the output ratio of the first laser beam and the second laser beam, or the output of at least one of the beams, without having to make precise adjustments to the distance between the prism and the cylindrical lens or the optical axis of the prism. In other words, since the outputs of the core section and the ring section are configured to be independently changeable or the output ratio can be changed, adjustments that would change the length of the weld marks are unnecessary, and emitted light with a desired intensity distribution or beam profile can be easily emitted.
[0023] 2. Laser Processing Method The laser processing method according to this disclosure comprises the following steps: laser emission step, splitting and reversal step, focusing step, and welding step.
[0024] 2.1 Laser Emission Process In the laser emission process, a first laser beam with an annular cross-section and a second laser beam with a cross-section surrounded by the first laser beam are emitted.
[0025] 2.2 Splitting and Inversion Process In the splitting and inversion process, the first laser beam and the second laser beam are transmitted through a prism and split to invert the beam profile.
[0026] 2.3 Focusing Process In the focusing process, the divided first laser beam and second laser beam are transmitted through a cylindrical lens and focused to emit an output beam having a flattened beam cross-section.
[0027] 2.4 Welding Process In the welding process, the first workpiece and the second workpiece are welded together by irradiating them with light from the first workpiece side.
[0028] This process makes it possible to easily fine-tune the intensity distribution within the beam cross-section of the emitted light without having to make precise adjustments to the distance between the prism and the cylindrical lens, or the optical axis of the prism.
[0029] The emitted light may be irradiated multiple times from the first workpiece side to form multiple weld marks.
[0030] Examples of the first workpiece include a lead with one end connected to the electrodes of a battery. Examples of the second workpiece include a current collector plate or battery can to which the other end of the lead is connected. However, the first and second workpieces are not limited to these.
[0031] 3. Specific Examples of Laser Processing Apparatus and Laser Processing Method Below, examples of laser processing apparatus and laser processing method relating to this disclosure will be specifically described with reference to the drawings. The components and processes of the laser processing apparatus and laser processing method in the examples described below can be adapted to the components and processes described above, and can be modified based on the above description. Furthermore, the matters described below may be applied to the embodiments described above. Among the components and processes of the laser processing apparatus and laser processing method in the examples described below, components and processes that are not essential to the laser processing apparatus and laser processing method relating to this disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the actual shape and number of components.
[0032] First, the configuration of the laser processing apparatus 1 of this embodiment will be described, and then the laser processing method of this embodiment will be described.
[0033] Figure 1 is a schematic diagram illustrating the configuration of a laser processing apparatus 1 according to one embodiment of the present disclosure. Figure 2 is a schematic diagram illustrating the configuration of a laser emission unit 10 provided in the laser processing apparatus 1. Figure 3(a) is a schematic diagram illustrating the beam cross-sections of the first laser beam L1 and the second laser beam L2 emitted from the laser emission unit 10. Figure 3(b) is a schematic diagram illustrating the intensity distribution of the first laser beam L1 and the second laser beam L2. Figure 4(a) is a schematic diagram illustrating the cross-section of the emitted light Lout emitted from the laser processing apparatus 1. Figure 4(b) is a schematic diagram illustrating its intensity distribution. Figure 5 is an explanatory diagram illustrating a simplified, flattened beam cross-section of the emitted light Lout. Figure 6 is an explanatory diagram illustrating a welding process in the laser processing method according to the present disclosure. Note that in Figure 2, the first laser beam L1 and the second laser beam L2 are schematically shown.
[0034] 3.1 Laser Processing Apparatus 1 The laser processing apparatus 1 of this embodiment comprises a laser emission unit 10, a prism 20, and a cylindrical lens 30, as shown in Figure 1. The laser emission unit 10 emits a first laser beam L1 (see Figure 3(a)) with an annular beam cross-section and a second laser beam L2 (see Figure 3(a)) with a beam cross-section surrounded by the first laser beam. The prism 20 splits the first laser beam L1 and the second laser beam L2 by transmitting them, thereby inverting the beam profile. The cylindrical lens 30 focuses the split first laser beam L1 and the second laser beam L2 by transmitting them.
[0035] As shown in Figure 2, the laser emission unit 10 includes an output adjustment unit 11, a laser light source 12, and a laser light forming unit 13. The laser light source 12 emits laser light. The laser light forming unit 13 forms a first laser beam L1 and a second laser beam L2 from the laser light emitted from the laser light source 12. The output adjustment unit 11 changes the output ratio of the first laser beam L1 and the second laser beam L2, or the output of at least one of the first laser beam L1 and the second laser beam L2.
[0036] With this configuration, the laser processing apparatus 1 emits an output light Lot (see Figure 4(a)) having a flattened beam cross-section. When this output light Lot is irradiated onto the workpiece W, welding and other processes can be performed effectively. Since the beam profile is inverted by the prism 20, as shown in Figure 4(b), the first laser beam L1, which has an annular beam cross-section, corresponds to both ends of the output light Lot, and the second laser beam L2 corresponds to the central part of the output light Lot. This prevents a decrease in intensity at both ends of the output light Lot.
[0037] 3.2 Laser Processing Method The laser processing method according to this disclosure comprises the following steps: laser emission step, splitting and reversal step, focusing step, and welding step.
[0038] In the laser emission process, as shown in Figure 1, a first laser beam L1 (see Figure 3(a)) with an annular beam cross-section and a second laser beam L2 (see Figure 3(a)) with a beam cross-section surrounded by the first laser beam L1 are emitted.
[0039] In the splitting and inversion process, as shown in Figure 1, the first laser beam L1 and the second laser beam L2 are transmitted through the prism 20 and split to invert the beam profile.
[0040] In the focusing process, as shown in Figure 1, the divided first laser beam L1 and second laser beam L2 are transmitted through the cylindrical lens 30 and focused to emit an output light output having a flattened beam cross-section.
[0041] In the welding process, as shown in Figure 6, the emitted light Lout is irradiated onto the first workpiece W1 and the second workpiece W2 from the first workpiece W1 side to weld the first workpiece W1 and the second workpiece W2 together. The emitted light Lout may be irradiated multiple times from the first workpiece W1 side to form multiple flat-shaped weld marks M that can approximate multiple rectangles. In Figure 6, the first workpiece is shown as a lead with one end connected to the electrode of a battery, and the second workpiece is shown as a current collector plate to which the other end of the lead is connected, but the first workpiece W1 and the second workpiece W2 are not limited to these.
[0042] This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its essence. Furthermore, various disclosures can be formed by appropriately combining the multiple components disclosed in the embodiments described above. For example, some components may be removed from all the components shown in the embodiments. The drawings schematically show each component for ease of understanding, and the number of each component shown may differ from the actual number due to the convenience of drawing creation. In addition, each component shown in the embodiments described above is an example and is not particularly limiting, and various modifications are possible without substantially departing from the effects of this disclosure.
[0043] 4. The following technologies are disclosed by the above descriptions of embodiments. (Technology 1) A laser processing apparatus that emits light having a flattened beam cross-section, comprising: a laser emission unit that emits a first laser beam having an annular beam cross-section and a second laser beam having a beam cross-section surrounded by the first laser beam; a prism that transmits the first laser beam and the second laser beam, thereby splitting them and inverting the beam profile; and a cylindrical lens that transmits the split first laser beam and the second laser beam, thereby focusing them. (Technology 2) The laser processing apparatus according to Technology 1, further comprising an output adjustment unit that changes the output ratio of the first laser beam and the second laser beam, or the output of at least one of the first laser beam and the second laser beam. (Technology 3) The laser processing apparatus according to Technology 1 or 2, wherein the laser emission unit comprises a laser light source that emits laser light and a laser light forming unit that forms the first laser beam and the second laser beam from the laser light emitted from the laser light source. (Technology 4) A laser processing apparatus according to any one of Techniques 1 to 3, wherein, if the major axis of the flattened shape is L and the minor axis is W, the ratio of the perimeter PL1 of the beam cross-section of the emitted light to 2(L-W)+πW is 1 or more and 2 or less. (Technology 5) A laser processing apparatus according to any one of Techniques 1 to 4, wherein the wavelengths of the first laser light and the second laser light are 100 nm or more and 2000 nm or less. (Technology 6) A laser processing apparatus according to any one of Techniques 1 to 5, wherein the prism divides the first laser light and the second laser light into two by transmitting them through it.(Technology 7) A laser emission step of emitting a first laser beam with an annular beam cross-section and a second laser beam with a beam cross-section surrounded by the first laser beam, respectively; a splitting and inversion step of transmitting the first laser beam and the second laser beam through a prism, splitting them, and inverting the beam profile; a condensing step of transmitting the split first laser beam and second laser beam through a cylindrical lens to condense them and emit an output beam having a flat beam cross-section; and a welding step of irradiating the output beam from the side of the first workpiece to the first workpiece and the second workpiece to weld the first workpiece and the second workpiece. A laser processing method. (Technology 8) The laser processing method according to Technology 7, wherein the first workpiece is a lead having one end connected to an electrode of a battery, and the second workpiece is a current collector plate or a battery can to which the other end of the lead is connected. (Technology 9) The laser processing method according to Technology 7 or 8, wherein the output beam is irradiated from the side of the first workpiece a plurality of times to form a plurality of welding marks.
[0044] The present disclosure can be used in a laser processing apparatus and a laser processing method.
[0045] Although the present invention has been described with respect to a preferred embodiment at the present time, such a disclosure should not be construed in a limiting manner. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the technical field to which the present invention pertains upon reading the above disclosure. Therefore, the appended claims should be construed to encompass all modifications and alterations without departing from the true spirit and scope of the present invention.
[0046] 1 Laser processing apparatus 10 Laser emission unit 11 Output adjustment unit 12 Laser light source 13 Laser light forming unit 20 Prism 30 Cylindrical lens L1 First laser beam L2 Second laser beam Lout Output beam M Welding mark W1 First workpiece W2 Second workpiece
Claims
1. A laser processing apparatus comprising: a laser emission unit that emits a first laser beam having an annular beam cross-section and a second laser beam having a beam cross-section surrounded by the first laser beam; a prism that transmits the first and second laser beams to split them and invert the beam profile; and a cylindrical lens that transmits the split first and second laser beams to focus them, thereby emitting an output beam having a flattened beam cross-section.
2. (Additional configuration for easily adjusting beam intensity distribution) The laser processing apparatus according to claim 1, further comprising an output adjustment unit for changing the output ratio of the first laser beam and the second laser beam, or the output of at least one of the first laser beam and the second laser beam.
3. The laser processing apparatus according to claim 1 or 2, wherein the laser emission unit comprises a laser light source that emits laser light, and a laser light forming unit that forms the first laser light and the second laser light from the laser light emitted from the laser light source.
4. The laser processing apparatus according to claim 1 or 2, wherein, if the major axis of the flattened shape is L and the minor axis is W, the ratio of the perimeter PL1 of the beam cross-section of the emitted light to 2(L-W)+πW is 1 or more and 2 or less.
5. The laser processing apparatus according to claim 1 or 2, wherein the wavelengths of the first laser light and the second laser light are 100 nm or more and 2000 nm or less.
6. The laser processing apparatus according to claim 1 or 2, wherein the prism divides the first laser beam and the second laser beam into two by transmitting them through it.
7. A laser processing method comprising: a laser emission step of emitting a first laser beam having an annular beam cross-section and a second laser beam having a beam cross-section surrounded by the first laser beam; a splitting and inversion step of transmitting the first laser beam and the second laser beam through a prism to split them and invert the beam profile; a focusing step of transmitting the split first laser beam and the second laser beam through a cylindrical lens to focus them and emit an emitted beam having a flattened beam cross-section; and a welding step of irradiating a first workpiece and a second workpiece from the first workpiece side to weld the first workpiece and the second workpiece together.
8. The laser processing method according to claim 7, wherein the first workpiece is a lead with one end connected to an electrode of a battery, and the second workpiece is a current collector plate or battery can to which the other end of the lead is connected.
9. The laser processing method according to claim 7 or 8, wherein the emitted light is irradiated multiple times from the first workpiece side to form multiple weld marks.