Laser processing method and device for ultra-hard materials, and machine tool

Abstract

A method for laser processing of super-hard materials, characterized in that the direct relationship between the direction of the contour processing trajectory on the work surface and the polarization direction is separated by moving a focused light spot (100) having linear polarization characteristics and changing the polarization azimuth angle, and the polarization direction is related only to the movement of the galvanometer.

Description

[Technical Field]

[0001] The present invention relates to a method for performing material processing with a laser, in particular a method for performing ultra-hard material processing with a laser to form a continuous, chip-free cutting edge, and an apparatus and machine tool using the method. [Background technology]

[0002] Polarization of light is the phenomenon in which the spatial distribution of the electric vector vibration of a light wave loses symmetry with respect to the direction of light propagation. This is a phenomenon in which the vibration vector of a transverse wave of light (perpendicular to the direction of wave propagation) is polarized in a specific direction. When light propagates, the vibration direction of the light vector is limited to a certain plane; this light is called linearly polarized (or plane polarized), and it vibrates only in a certain direction, with its magnitude changing depending on the phase but its direction remaining constant. When the vibration vector changes periodically, it can be classified as elliptically polarized or circularly polarized depending on the period of change. When the locus of the end points of the light vector is elliptical, i.e., the light vector rotates continuously and its magnitude and direction change regularly over time, it is elliptically polarized light. When the locus of the end points of the light vector is circular, i.e., the light vector rotates continuously, its magnitude remains constant, and its direction changes regularly over time, it is circularly polarized light.

[0003] We use a coordinate system defined by the plane containing the input and reflected beams. If the polarization vector of the light lies within this plane, it is called P-polarized. If the polarization vector is perpendicular to this plane, it is called S-polarized.

[0004] Vector polarization is non-uniform polarization with an axially symmetric polarization structure. The magnitude of the electric field on the optical axis is the same but the polarization direction is opposite, resulting in different polarization states at each point on the beam cross section. The direction of the electric field vector at any point on the cross section of a radially polarized beam is always parallel to the radial direction, i.e., each direction passing through the center of the circle. Radial polarization refers to polarization whose polarization direction is along the radial direction on the cross section. Radial polarization distribution has an annular spot mode distribution and belongs to the annular beam mode. Unlike a Gaussian beam on a typical base film, the light intensity distribution of an annular beam mode is characterized by zero intensity on the optical axis and the strongest intensity in the annular area surrounding the optical axis. The light intensity distribution resembles a ring. Angular polarization refers to light whose polarization direction is perpendicular to the radial direction on the cross section, and its light intensity distribution also resembles a ring.

[0005] Currently, laser cutting (including pulsed and continuous lasers) is widely used in cutting and marking sheet metal and profile materials, as well as in other fields such as tool machining of ultra-hard materials. Improving production efficiency is always a key issue in industrial manufacturing. In research, engineers have recognized that in addition to the power, frequency, and pulse width of a pulsed laser beam, the polarization state of the beam also affects processing efficiency and quality. For example, studies by Fan et al. of the Institute of Laser Technology at Huazhong University of Science and Technology (Laser Technology, Vol. 12, No. 5) and Li et al. of the School of Science at Xi'an University of Technology (Laser Application Technology, Vol. 12, Issue 40, Vol. 12) both demonstrated that circularly polarized (C-state) beams have improved processing efficiency and quality compared to linearly polarized (P-state, S-state) beams. Linearly polarized lasers have different characteristics, such as slit width and slag sagging, in different processing directions. Although some studies have shown that the processing efficiency and processing quality of radially polarized (R-state) beams are superior to that of circularly polarized (C-state) beams, circular polarization is still the most widely used in actual industrialized laser processing applications, while angular polarization (A-state) and radial polarization (R-state) are mainly used in non-processing laser optical systems such as optical tweezers. This is mainly because, although there are many technical means that can change or modulate the polarization state of lasers, due to technical conditions and cost factors, there are no reports of technical means for controlling the angular and radial polarization of medium and high power lasers in the application of industrial machine apertures.

[0006] Currently, for machining ultra-hard material tools, mainly diamond tools, electrical discharge wire cutting, grinding, lasers and the like are mainly used.

[0007] When manufacturing precision diamond milling cutters for micromachining, the roughness of the machined surface by EDM is relatively high, and it is difficult to avoid layout or total damage (i.e., chipping) to the edge of the machined area (i.e., the cutting edge line). This results in low machining efficiency, and the blade arc radius formed is basically determined by the grain size of the material, making it difficult to obtain a high-quality, sharp cutting edge (a cutting edge arc radius of less than 1,000 nanometers, a continuous cutting edge line, and no chipping).

[0008] Grinding can achieve excellent surface roughness and a sufficiently small cutting edge arc radius through process management, but it is prone to chipping, has very low processing efficiency (less than one-third of the cutting efficiency of electric discharge wire), and cannot process complex shapes (two-dimensional contours other than straight lines or arcs).

[0009] Currently, laser technology used to process ultra-hard material cutting tools mainly uses short-pulse and ultra-fast lasers, which can achieve surface roughness similar to that achieved by grinding or polishing. This non-contact, stress-free processing method allows for the machining of blades of any shape, with little chipping and very high single-pass processing efficiency. However, due to the focusing characteristics of lasers, the focused laser beam is conical, forming a cone. Within the entire cone, only the focused light spot (i.e., the area where the apex of the light cone is located) has the energy density required to remove material. The light energy density in the axial cross section of the focused light cone is low, making it difficult to achieve material removal. As a result, in terms of the material processing depth, lasers cannot penetrate the material in a single pass in the direction perpendicular to the plane (i.e., usually representing the thickness). Instead, the laser scans the processing surface point by point, layer by layer, vaporizing the material layer by layer until it penetrates the material and removing all of the material in the direction perpendicular to the plane. To further complicate matters, when the laser processing depth increases during layer-by-layer processing, if the processing width near the initial processing plane is too narrow and part of the focused light cone is blocked by the workpiece surface (i.e., the light spot cannot contact the material), the focused light spot cannot obtain sufficient energy density to further remove material and ultimately cannot penetrate the material completely. Therefore, laser processing often requires a starting processing width several tens of times the diameter of the focused light spot. Therefore, multiple passes are required to complete material removal, regardless of the laser processing depth or processing plane. Therefore, the efficiency of laser processing for ultrahard material tools is comparable to that of wire-cutting. Increasing the laser power, i.e., increasing the energy density of the entire laser light cone, is a solution, but increasing the power also increases surface roughness, making fine processing (surface roughness Ra = 20-50 nm) impossible. On the other hand, some studies have shown that by controlling the processing direction (for example, by applying the laser from the interference surface on the back side of the tool), it is possible to obtain a laser-processed blade with a cutting edge arc radius of less than 1000 nanometers. However, the cutting edge arc radius obtained by laser processing is generally fixed at a certain value between 1000 and 5000 nm, and does not have accurate and flexible adjustment capabilities.

[0010] To improve processing quality and efficiency, prior art technologies such as CN103189160B also modulate the polarization state of the laser beam, but by using a circularly or randomly polarized focused light spot, the light spot moves continuously along the contour locus of the workpiece surface to perform laser processing. Prior art technologies such as CN209424743U and CN111730214A also modulate the polarization state of the laser beam, but by using a focused light spot to move continuously directly along the contour locus of the workpiece surface to perform laser processing. The linear polarization direction of the laser beam always tangent to the contour processing locus during movement. However, these technologies do not fully consider the impact on processing efficiency and effectiveness in two dimensions, the plane of the laser and the plane perpendicular to the plane, in actual processing production.

[0011] Therefore, a technical solution for efficiently and industrially producing a super-hard material cutting tool that is free from chipping, has an arbitrary shape, has a smooth flank (i.e., a surface roughness similar to that of a ground or polished surface), and has various cutting edge arc radii is unprecedented and not well known to those skilled in the art, making it a technical problem that must be solved as soon as possible. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Chinese Patent No. 103189160 [Patent Document 2] Chinese Utility Model No. 209424743 [Patent Document 3] Chinese Patent Application Publication No. 111730214 Summary of the Invention [Problem to be solved by the invention]

[0013] One object of the present invention is to provide a laser processing method for ultra-hard materials that is advantageous for forming a continuous cutting edge line without chipping, particularly a cutting edge with an arc radius of 1,000 to 5,000 nm.

[0014] Another object of the present invention is to provide a laser processing method for ultra-hard materials, which performs micro-processing (surface roughness Ra=20 to 50 nm) on ultra-hard materials.

[0015] It is still another object of the present invention to provide a method for laser processing of ultra-hard materials that improves the processing efficiency of ultra-hard materials.

[0016] Another object of the present invention is to provide a laser processing method for ultra-hard materials that is applicable to multi-axis processing devices (such as five-axis machine tools) and is advantageous for performing laser precision processing on cutting edge arc radii of various specifications.

[0017] The fifth object of the present invention is to provide an apparatus for laser processing of super-hard materials, which not only realizes processing of cutting edge arc radius according to need on super-hard materials and reduces surface roughness but also effectively reduces processing costs. [Means for solving the problem]

[0018] As commonly understood, a laser is light emitted by atoms stimulated to do so. When electrons in atoms absorb energy, jump from a lower energy level to a higher energy level, and then return from the higher energy level to the lower energy level, the released energy is released in the form of photons. Laser types can be divided into continuous lasers and pulsed lasers. Lasers can be divided into hot lasers and cold lasers according to their pulse width characteristics.

[0019] The laser oscillator may be a nanosecond, femtosecond, or picosecond laser, and may generate laser light such as, but not limited to, infrared, blue light, green light, violet light, or extreme violet light.

[0020] The light source is used to emit a laser beam, and may be a continuous laser source or a pulsed laser source, preferably a pulsed laser source. When a pulsed laser source is used, the pulse width is 50 fs to 500 ns, preferably 500 fs to 120 ns, the average power is 10 to 500 W, preferably 30 to 150 W, the pulse repetition frequency is 10 to 10,000 kHz, preferably 30 to 2,000 kHz, and the wavelength is 350 to 2,050 nm, preferably 520 nm to 1,200 nm.

[0021] In machining, the so-called workpiece is usually the material or semi-finished product used to manufacture a part or component, and is the object to be processed during the machining process, i.e., after machining the workpiece, a product that meets the processing or design requirements is obtained.

[0022] Precision machining is a processing technology that achieves extremely high levels of processing accuracy and surface quality. For example, in tool processing, size, straightness, contour, surface roughness, arc radius of cutting edge, processing accuracy, etc. can all be achieved at the micron level or less.

[0023] The superhard material may be a cermet, diamond (especially synthetic polycrystalline diamond) or cubic boron nitride, or a composite material formed of a hard alloy and one or more of a cermet, diamond and cubic boron nitride.

[0024] Diamond is a mineral composed of carbon, an allotrope of graphite, with the chemical formula C, and is the original form of common diamonds. Graphite can be used to form artificial diamonds under high temperature and pressure. Diamond hardness is directional; the octahedral crystal face is harder than the rhombic dodecahedral crystal face, which is harder than the hexahedral crystal face.

[0025] Diamond composite sheets, also known as polycrystalline diamond composite sheets, are made by sintering diamond powder and a hard alloy substrate under ultra-high pressure and high temperature conditions. They not only have the high hardness, high wear resistance, and thermal conductivity of diamond, but also the strength and impact resistance of hard alloys, making them an ideal material for cutting tool edges. Generally, both have mirror-polished surfaces, which are advantageous for tool manufacturing.

[0026] A machining device (or machining center) is a processing device with multiple motion axes. That is, in a right-handed Cartesian coordinate system, there are X, Y, and Z axes along which linear movement occurs, and A, B, and C axes that rotate around the X, Y, and Z axes, respectively. CNC machine tools, etc., are usually equipped with control software that sends and receives commands in coded form to automatically process workpieces.

[0027] The laser processing method for ultra-hard materials separates the direct relationship between the direction of the contour processing trajectory on the workpiece surface and the polarization direction by moving the focused light spot with linear polarization characteristics and changing the polarization azimuth angle, and associates the polarization direction only with the movement of the galvanometer.In direct laser processing, different types of polarization characteristics, such as linear polarization (P state, S state), circular polarization (C state), angular polarization (A state) and radial polarization (R state), can be dynamically controlled, switched, and mixed in the processing pattern.

[0028] In the laser processing method for ultra-hard materials, a focused light spot of a linearly polarized laser moves along a scanning path on a plane, and the polarization angle of the laser is controlled in real time during scanning. Each focused light spot is arranged along the scanning path in sequence with its own polarization angle to generate a processing pattern, which is then moved overall over the material surface to remove material along the moving path and obtain the required structure.

[0029] Compared to directly using other polarization state lasers (angular polarization, radial polarization, elliptically polarization, circular polarization, etc.) to process materials, this method, in which each laser has its own polarization angle arranged along the scanning path, allows the processing pattern formed by the focused light spot of a linearly polarized laser with a different specific polarization angle to replace a laser with another polarization state, and the processing performed on the material as a whole can achieve the same processing quality and efficiency.In addition, when the laser linear polarization state is P-polarized, the processing pattern can also be obtained in this way, achieving the same processing quality and efficiency as S-polarized, allowing one type of linear polarization to be applied to various processing requirements.

[0030] Since the movement of the focused light spot changes in synchronization with the polarization angle, the processing effect obtained by the processing pattern is similar to that obtained by directly using angular polarization and radial polarization processing.After that, it moves in the processing pattern along the processing trajectory of the workpiece surface contour, and removes the superhard material within the laser processing surface, thereby shortening the total length of the processing trajectory, increasing the processing depth per pass, and achieving blade processing with the required cutting edge arc radius.

[0031] Another method for laser processing ultra-hard materials involves using a laser to emit a focused light spot through the galvanometer, which acts on the laser processing plane, scans the focused light spot along a set scanning path to form a processing pattern, and moves along the contour processing locus on the workpiece surface using the processing pattern to remove the ultra-hard material within the laser processing plane. When the focused light spot scans along the set scanning path, the relationship between the polarization direction and the scanning path is further set, and the focused light spot moves around the center of the processing pattern to generate processing patterns equivalent to the processing effect of a focused light spot directly using P-polarized light, S-polarized light, A-polarized light, R-polarized light, C-polarized light, elliptically polarized light, or a combination of A and R polarized light.

[0032] The correlation between polarization direction and scan path includes the following: Because the polarization direction of each focused light spot positioned sequentially along the scanning path is the same, the resulting processing pattern has overall linear polarization characteristics. The polarization direction is uncorrelated with the scanning path and is set perpendicular to the incident plane of the laser processing plane, resulting in a processing pattern similar to P-state polarization characteristics. The polarization direction is uncorrelated with the scanning path and is set parallel to the incident plane of the laser processing plane, resulting in a processing pattern similar to S-state polarization characteristics.

[0033] The loci of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all located on tangents to the scanning path of the focused light spot, giving the processed pattern angular polarization characteristics as a whole.

[0034] The loci of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all located on a straight line passing through the center of the processing pattern, and the processing pattern as a whole has radial polarization characteristics.

[0035] The locus of the light vector end point of each focused light spot on a plane perpendicular to the propagation direction all intersects with the tangent to the scanning path of the focused light spot, and the intersection angle is greater than 0° and less than 180°, so that the processing pattern as a whole has both angular polarization and radial polarization properties.

[0036] The locus of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction changes periodically and continuously, so that the processed pattern as a whole has circular polarization characteristics or elliptically polarization characteristics.

[0037] By using a polarization driver, the polarization azimuth angle of the emitted laser (referring to the laser passing through the polarization driver) is changed in real time. Preferably, a mechanical device consisting of a hollow rotary motor and a polarization optical element (such as a half-wave sheet or Faraday rotator) placed inside it is selected. The laser beam passes through the central through-hole of the motor and the polarization optical element placed on the motor, and the rotation of the polarization optical element is driven by controlling the motor, changing the polarization direction of the emitted light.

[0038] To implement the laser processing method, the present invention includes: a laser light source that generates a laser beam; a reflector for changing the direction of the laser beam; a focusing lens that receives the incident laser beam and forms a focused light spot; a galvanometer for controlling the scanning range of the focused light spot; a polarization driver that changes the polarization azimuth angle of the emitted laser; The present invention further provides an apparatus comprising:

[0039] The reflector of the present invention is attached to an optical adjustment frame or a galvanometer, and changes the scanning direction of the focused light spot as needed to form the machining pattern.

[0040] The focusing lens of the present invention is comprised of at least one lens, preferably a multi-lens field lens.

[0041] Taking the machining of tools made of superhard materials as an example, the machining device using the method provided by the present invention enables highly efficient industrial production of superhard material tools that are chipping-free, have any shape, have a smooth cutting edge surface, and can selectively obtain various cutting edge arc radii. [Effects of the Invention]

[0042] The beneficial effects achieved by the technical solution of the present invention are as follows: The method proposed by this invention involves continuously scanning a focused light spot with linear polarization characteristics along a scanning path on a laser processing surface to form a processing pattern. During this process, the focused light spot moves and the polarization angle changes simultaneously, so the processing effect achieved by the processing pattern is equivalent to that achieved by directly using angular polarization and radial polarization processing. The processing pattern is then moved along the contour processing trajectory of the workpiece surface, shortening the overall processing trajectory and increasing the processing depth per pass, thereby achieving blade processing with the required cutting edge arc radius.

[0043] The method provided by the present invention separates the direct relationship between the trajectory direction of the workpiece surface contour machining and the polarization direction, and the polarization direction is related only to the scanning direction of the focused light spot controlled by the galvanometer. Meanwhile, by replacing the medium- to low-speed mechanical axis movement with the high-speed reciprocating movement of the galvanometer, the width and depth lengths of the machining trajectory are significantly shortened, and machining efficiency is improved.

[0044] The method provided by the present invention combines the movement of a linearly polarized beam and the change in its polarization orientation without using complex optical elements such as a conical total reflection mirror, thereby achieving machining patterns with angular polarization characteristics and radial polarization characteristics similar to those achieved using only a conical total reflection mirror or intracavity shaping technology. In machining applications for tools made of superhard materials, this method enables control and polarization of the cutting edge arc radius while achieving higher machining efficiency than circularly polarized light machining.

[0045] Taking superhard material tool processing as an example, under the same laser power, when the method of the present invention is applied, not only can the material removal rate of conventional laser direct writing processing technology be significantly improved by at least 20%, but also the depth of material removal per time can be increased and the tool division in the planar direction can be reduced, thereby significantly shortening the total processing path length by more than 50%, and improving the overall processing efficiency by an average of more than 50%.

[0046] By applying the method of the present invention, the flexibility of conventional laser direct writing processing technology is greatly improved, and it becomes possible to control the surface roughness and edge sharpness of the laser processing area as needed, provided that parameters such as power, frequency, and pulse width are not changed. Taking the processing of polycrystalline diamond material tools as an example, it is possible to achieve a processed surface roughness of Ra 0.05 microns and a cutting edge arc radius of 1000 nanometers or less. [Brief explanation of the drawings]

[0047] [Figure 1] FIG. 2 is an illustration of one embodiment of a focused light spot. [Figure 2] FIG. 2 is an explanatory diagram of an embodiment of a laser processing plane. [Figure 3]1 is an illustration of an embodiment of a processing pattern formed by scanning a focused light spot along a scanning path. [Figure 4] 10A and 10B are diagrams illustrating another embodiment of a processing pattern formed by scanning a focused light spot across a laser processing plane. [Figure 5] FIG. 1 is an illustration of one embodiment of a focused light spot of linear polarization. [Figure 6] FIG. 1 is an illustration of a computer simulation of scanning a laser processing plane with a focused light spot having linear polarization state characteristics. [Figure 7] FIG. 10 is an explanatory diagram of an embodiment in which a polarizing device is driven to adjust linear polarization. [Figure 8] 8 is an explanatory diagram of an embodiment in which the linear polarization state obtained in FIG. 7 is adjusted and the laser processing plane is scanned. FIG. [Figure 9] FIG. 10 is a diagram illustrating the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of the method of the present invention in a quasi-P or quasi-S polarization state. [Figure 10] FIG. 10 is a diagram illustrating the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of a quasi-C polarization state according to the method of the present invention. [Figure 11] FIG. 10 is an explanatory diagram of the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of the quasi-A polarization state according to the method of the present invention. [Figure 12] FIG. 10 is a diagram illustrating the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of a quasi-R polarization state according to the method of the present invention. [Figure 13] FIG. 10 is a diagram illustrating the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of a composite polarization state of quasi-A and quasi-R according to the method of the present invention. [Figure 14] 10A to 10C are explanatory diagrams illustrating the distribution of polarization azimuth angles at various locations on a processing pattern to obtain various types of processing effects when the method of the present invention is applied to a rectangular boundary. [Figure 15] 10 is a diagram illustrating the distribution of polarization azimuth angles at various locations on a processing pattern that achieves the processing effect of the mixed characteristics of a plurality of polarization states according to the method of the present invention. FIG. [Figure 16] FIG. 1 is an illustration of one embodiment of a prior art laser machined slit path. [Figure 17] FIG. 2 is an illustration of one embodiment of a slit laser machining path of the method of the present invention. [Figure 18] 18 is an explanatory diagram of another angle of the laser processing path shown in FIG. 17. DETAILED DESCRIPTION OF THE INVENTION

[0048] The technical solution of the present invention will be described in detail below with reference to the drawings. The embodiments of the present invention are for illustrating the technical solution of the present invention, but are not intended to limit it. The present invention will be described in detail with reference to preferred embodiments. However, as can be understood by those skilled in the art, modifications or equivalent substitutions can be made to the technical solution of the invention, and should be included in the scope of the claims of the present invention as long as they do not deviate from the spirit and scope of the technical solution of the present invention.

[0049] When using a laser to process a super-hard material, the structure of the super-hard material to be processed and removed is determined, and the contour of the super-hard material structure is determined. The workpiece plane where the focused light spot is located is the laser processing plane, and the contour of this plane defines the first boundary of the laser processing. The entire path from when the laser first contacts the structure to when it finally passes completely through the structure is the second boundary, which is usually also recognized as the laser processing depth.

[0050] Taking the machining of a thick circular hole as an example, the contour of the ultra-hard material structure to be machined and removed is a cylinder, and the plane where the contour intersects with the laser incident direction is the laser machining plane, which is circular. The circular contour is the first boundary of the laser machining, and the laser focused light spot 100 (the outline of which is shown in FIG. 1) acts within the first boundary to remove the hard material within the first boundary.

[0051] Typically, the area of ​​the focused light spot acting on the laser processing plane is equal to or smaller than the first boundary. When the area of ​​the focused light spot is equal to the first boundary, a single action can remove all of the ultra-hard material within the laser processing plane where the energy of the focused light spot reaches. When the area of ​​the focused light spot acting on the laser processing plane is smaller than the first boundary, the focused light spot must usually be applied to the laser processing plane multiple times to remove the ultra-hard material where the energy of the focused light spot reaches. As the processing depth increases, the laser processes the ultra-hard material along the first boundary, removing it layer by layer.

[0052] The area of ​​material removal can be increased by overlapping several focused light spots 100. For example, as shown in Figure 2, if the entire area defined by the circular boundary 400 acts on the ultra-hard material, the ultra-hard material removal efficiency can be improved and the processing time can be reduced. To achieve this goal, the focused light spot needs to be moved along a scanning path to form a processing pattern within the circular boundary 400.

[0053] By controlling the galvanometer, the laser spot can be caused to form a processing pattern along the scanning path. As shown in FIG. 3, the focused light spot 100 scans along a circular scanning path 300, thereby forming a processing pattern 200. The focused light spot 100 acts multiple times, overlapping to form the processing pattern. Comparing FIG. 3 with FIG. 4, it can be seen that to completely remove the superhard material within the circular boundary 400, the frequency of the focused light spot 100 action must be increased, i.e., the density must be increased. Although these processing patterns cannot be completely realized on the structure, as the focused light spot moves, the focused light spots at each instant are combined, and a complete processing pattern located within the circular boundary 400 can be seen, for example, through computer simulation. Therefore, at the start of processing the laser processing plane, the complete processing pattern located within the circular boundary 400 can be generated, the area acting on the superhard material can be expanded, and the entire processing pattern can be moved across the superhard material to form a structure, such as a wide slit (compared to the slit created in the superhard material by a single focused light spot). Such patterns are usually obtained by drawing, but with the aid of a computer, drawing efficiency can be improved and processing data for the focused light spot, such as processing coordinates and movement speed, can be created, which helps to realize the automation of laser processing on CNC machine tools. That is, the focused light spot scans the laser processing plane along the set processing pattern to remove the superhard material.

[0054] After the laser beam is emitted from the light source, it undergoes a series of (conventional) changes such as beam expansion and collimation, passes through a polarization driver, and enters a galvanometer. The beam direction is changed by the computer-controlled galvanometer reflector to scan the desired processing pattern, and the redirected laser is finally focused by a field lens to form a specific processing pattern consisting of the scanning path of the focused light spot. The focused light spot of the laser emitted from the galvanometer acts on the laser processing plane, and the focused light spot scans along the set scanning path to form the processing pattern, and then moves along the workpiece surface contour processing locus in the processing pattern to remove the super-hard material in the laser processing plane.

[0055] The focused light spot moves around the center of the machining pattern, changing synchronously with the polarization angle. Each focused light spot is positioned sequentially along the scanning path with its own polarization angle to generate a machining pattern. The machining pattern then moves as a whole across the workpiece surface to remove material, achieving machining quality and efficiency equivalent to that achieved when angular and radial polarization were directly used to remove material. Figure 5 shows the focused light spot 110 with linear polarization characteristics in this embodiment, machining a superhard material within a circular boundary. As shown in Figure 6, the polarization azimuth angle of the focused light spot does not change at each time. Before scanning the laser across the machining surface, the resulting machining pattern can be determined by computer simulation. During machining, scanning along the scanning path achieves a machining effect equivalent to the machining pattern. During the process of the focused light spot removing the superhard material, the polarization azimuth angle of the laser is controlled in real time based on the scanning speed of the focused light spot or feedback signals from the reflector position to ensure that the tolerance angle between the polarization direction of the emitted linearly polarized light and the current movement direction of the focused light spot along the scanning path satisfies the required machining angle. These processing angles are typically set according to the processing conditions. By adjusting the scanning path and polarization direction of the focused light spot and the angle between the scanning path and the polarization direction, various processing patterns can be obtained. These processing patterns are equivalent to the processing effects produced by lasers with polarization characteristics when processing ultrahard materials. For example, by setting the polarization direction perpendicular or parallel to the incident plane of the laser processing plane, rather than correlating it with the scanning path, processing patterns with polarization characteristics similar to the P-polarized or S-polarized state can be obtained. The patterns shown in Figure 9 correspond to the effects of laser processing in the P-polarized or S-polarized state, and are therefore referred to as quasi-P-polarized or quasi-S-polarized state processing patterns. Furthermore, for example, the trajectories of the optical vector endpoints of each focused light spot on a plane perpendicular to the propagation direction change periodically and continuously, resulting in processing patterns with polarization characteristics similar to the C-polarized state. The pattern shown in Figure 10 is equivalent to the effects of laser processing in the C-polarized state, and is therefore referred to as a quasi-C-polarized state processing pattern. Furthermore, for example, the loci of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all located on tangents to the scanning path of the focused light spot, so the processing pattern as a whole has angular polarization characteristics.The pattern shown in Figure 11 is referred to as a quasi-A polarization state processing pattern because it has the same effect as laser processing in the A polarization state. Furthermore, for example, the loci of the optical vector endpoints of each focused light spot on a plane perpendicular to the propagation direction are all located on a straight line passing through the center of the processing pattern, thereby giving the processing pattern overall radial polarization characteristics. The scanning pattern shown in Figure 12 is referred to as a quasi-R polarization state processing pattern because it has the same effect as laser processing in the R polarization state. By adjusting the processing angle, the scanning pattern can also achieve a combined laser processing effect of the A polarization state and the R polarization state. As shown in Figure 13, the loci of the optical vector endpoints of each focused light spot on a plane perpendicular to the propagation direction all intersect with the tangent to the scanning path of the focused light spot, and the intersection angle is greater than 0° and less than 180°, giving the processing pattern overall both angular polarization characteristics and radial polarization characteristics. Therefore, it is referred to as a combined quasi-A and quasi-R polarization state processing pattern. By changing the scanning path and combining lasers with specific polarization characteristics, various patterns can be formed, such as square, circular, dot, line patterns, and combinations thereof, as shown in Figure 14, thereby realizing processing of various complex shapes. By combining and setting the polarization direction and scanning path, it is possible to obtain processing patterns with processing effects that combine the characteristics of multiple polarization states, as shown in Figure 15, which can meet complex processing requirements.

[0056] As shown in Figure 7, the polarization driver 500 changes the polarization azimuth angle of the emitted laser beam (passing through the polarization driver) in real time. The polarization azimuth distribution of the focused light spots at each location on the processed pattern after the change is as shown in Figure 8, with all focused light spots located within the circular boundary 400. In this embodiment, a mechanical device consisting of a hollow rotary motor and a polarization optical element (such as a half-wave sheet or Faraday rotator) placed inside it is selected. The laser beam passes through the central through-hole of the motor and the polarization optical element placed on the motor, and the motor controls the rotation of the polarization optical element to change the polarization direction of the emitted light. The polarization driver may also include a quarter-wave sheet as a polarizer to ensure that the incident light entering the polarization optical element is linearly polarized. In addition to the mechanical rotation structure described above, the polarization driver may also be an electronic polarization driver consisting only of a liquid crystal retarder or liquid crystal polarization rotator without mechanical movement, or a combination of mechanical and electronic elements. Engineers can comprehensively determine the specific implementation method based on the required adjustment bandwidth and cost of the optical system.

[0057] By controlling the relationship between the laser polarization direction and the scanning path, it is possible to generate a processing pattern similar to the R state to increase the laser processing depth, or to generate a processing pattern similar to the A state to adjust the cutting edge arc radius as needed.

[0058] In tool processing, a focused light spot is generally used due to the focusing characteristics of the laser. The entire area of ​​the material to be removed must be scanned point by point and layer by layer. As shown in FIG. 16, the laser must be moved back and forth multiple times in the depth and plane directions to remove the material. In this embodiment, as shown in FIGS. 17 and 18, the processing pattern and the scanning path of the focused light spot are first determined according to the desired processing width on the laser processing plane, thereby effectively reducing the movement of the machine axis for each line of the focused light spot on the laser processing plane. For example, when cutting a slit of width N in a superhard material 600, if a focused light spot 100 with a diameter n is directly used, the machine axis must be moved back and forth N / n times on the laser processing plane. To achieve a slit depth of 1.6 mm in the superhard material, more than 40 passes are required. The focused light spot 110 with linear polarization characteristics controlled by a galvanometer is used to scan the pattern of width N, and the machine axis only needs to make a single relative movement along the length of the slit to cover and remove the entire area of ​​material, significantly improving processing efficiency.

[0059] By setting the quasi-polarization state of the processing pattern formed by scanning the focused light spot to the R state, which has a higher material removal rate, a larger single processing depth can be achieved and the layer-by-layer movement of the mechanical axis of the focused light spot in the depth direction can be reduced.The speed at which the galvanometer controls the pattern scanning is generally at least 10 times faster than the speed at which the mechanical axis is moved, so this processing method significantly improves the overall processing efficiency.

[0060] In the finishing process of tool blades, it is often necessary to machine tools with different cutting edge arc radii according to the different conditions of use (for example, a diamond micro-milling cutter for fine cutting requires a cutting edge arc radius of less than 300 nanometers, while a diamond replaceable blade abrasive used for rough cutting of titanium alloys requires a cutting edge arc radius of about 2,500 nm to 4,000 nm). In general, various processing technologies such as wire cutting, grinding, laser and polishing must be integrated to manufacture tool cutting edges with cutting edge arc radii within a certain size range, which significantly increases the connection and complexity of the production process. In this embodiment, the quasi-polarization state of the scanning pattern is set so that the polarization direction of the linearly polarized light emitted from the polarization driver maintains the angle between the polarization direction and the current movement direction of the focused light spot on the scanning path. This allows for a quasi-A-state (i.e., the polarization direction is always set parallel to the scanning path) or quasi-R-state (i.e., the polarization direction is always set perpendicular to the scanning path) machining pattern, or a machining pattern with a quasi-A-state and R-state hybrid polarization characteristic (i.e., the polarization direction is always set to maintain a constant angle with the scanning path). By using machining patterns with different polarization characteristics to remove the edges of ultra-hard materials, different edge sharpness can be controlled, i.e., cutting edges with different cutting edge arc radii can be obtained. Furthermore, asymptotic changes and differences in cutting edge sharpness can be achieved in different locations.

[0061] Taking a tool having the processing requirements shown in Tables 1 and 2 below as an example, processing is performed according to the laser processing schemes shown in Tables 3 and 4.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] [Table 4]

[0066] In summary, the laser processing method of this embodiment not only significantly improves processing efficiency, but also enables selectively obtaining a specific cutting edge arc radius, while achieving both a low processing surface roughness (Ra≦50 nm) and a reduced occurrence of cutting edge chipping.

[0067] In this embodiment of the laser processing method, the laser emitted from the laser oscillator first enters a portion of the cavity, then enters the laser projection relay member, where it changes its propagation path before being emitted. Finally, the laser is received by the light emitting member and emitted to perform processing on the workpiece. The laser propagates within the cavity, along a straight line, or along a curved line. The laser propagates along a straight line at the exit end of the cavity. In a right-handed Cartesian coordinate system, the rotation axis is the A-axis, B-axis, or C-axis. Therefore, the laser emitted by the light emitting member is distributed in a direction around the rotation axis and focused within the range of the rotation axis, i.e., within a rotation (circular) plane with a radius of 100 mm centered on the rotation axis, particularly on the rotation axis line. This enables the laser to perform machining by rotation. In this embodiment, the cavity is installed on the Y-axis, the rotation axis is the B-axis, and the light emitting member rotates around the B-axis.

[0068] The device provided in each of the above embodiments can be attached to a machining device, and for example, three linear motion axes, one rotary motion axis for fixing the workpiece, and one laser beam rotation axis can be combined to form a spatial five-axis laser processing technology solution, which can perform multi-axis machining on the workpiece and manufacture products with complex and diverse structures. For example, a machine tool has at least three linear axes, and one linear axis is equipped with the device of the present invention (e.g., installed on a plane defined by the X-axis and Z-axis and moving linearly along the Z-axis), and another linear axis is equipped with a rotary positioning mechanism to drive the rotational positioning of the workpiece to be processed (e.g., installed on a plane defined by the X-axis and Y-axis). This eliminates the situation where the relative position between the beam and the rotary stage rotation axis cannot be maintained due to factors such as stress, vibration, elastic deformation, or temperature, thereby improving the accuracy of laser processing and helping to perform laser processing on parts with various specifications. [Explanation of symbols]

[0069] 100 focused light spots 110 Focused light spot 200 processing patterns 300 scanning paths 400 circular boundary 500 Polarized Light Driver 600 Carbide material

Claims

1. A method for laser processing ultra-hard materials, characterized in that a direct relationship between the direction of a contour processing trajectory on a workpiece surface and the polarization direction is separated by moving a focused light spot having linear polarization characteristics and changing the polarization azimuth angle, and the polarization direction is related only to the movement of a galvanometer; A laser processing method for ultra-hard materials in which a focused light spot of a linearly polarized laser moves along a scanning path on a plane, the polarization angle of the laser is controlled in real time simultaneously with the scanning, and each focused light spot is arranged along the scanning path in sequence with its own polarization angle to generate a processing pattern, which is then moved overall over the material surface in the processing pattern, removing material along the moving path and obtaining the required structure.

2. 2. The method for laser processing of super-hard materials according to claim 1, wherein the polarization azimuth angle at which the laser is emitted is changed in real time by a polarization driving device, the laser beam passes through a through-hole in the center of the motor and a polarization optical element installed on the motor, and the motor is controlled to drive and rotate the polarization optical element, thereby changing the polarization direction of the emitted light.

3. 2. The method for laser processing ultra-hard materials according to claim 1, wherein the focused light spot moves around the center of the processing pattern and changes in synchronization with the polarization angle, and the focused light spots are sequentially positioned along the scanning path at their respective polarization angles to generate the processing pattern, and the processing pattern is moved overall on the workpiece surface to remove material, thereby achieving processing quality and processing efficiency equivalent to that achieved when material is removed directly using angular polarization and radial polarization.

4. The laser emits a focused light spot through the galvanometer and acts on the laser processing plane, the focused light spot scans along the set scanning path to form a processing pattern, and moves along the contour processing locus of the workpiece surface in the processing pattern to remove the super-hard material in the laser processing plane. When the focused light spot scans along the set scanning path, the relationship between the polarization direction and the scanning path is further set, and the focused light spot moves around the center of the processing pattern. When the polarization direction of each focused light spot arranged in sequence along the scanning path is the same, the entire generated processing pattern has linear polarization characteristics, or the optical vector end points of each focused light spot the trajectories of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all located on a straight line passing through the center of the processing pattern, giving the entire processing pattern radial polarization characteristics; the trajectories of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all located on a straight line passing through the center of the processing pattern, giving the entire processing pattern radial polarization characteristics; the trajectories of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are all intersecting with a tangent to the scanning path of the focused light spot at an intersection angle greater than 0° and less than 180°, giving the entire processing pattern both angular polarization and radial polarization characteristics; or the trajectories of the light vector end points of each focused light spot on a plane perpendicular to the propagation direction are periodically and continuously changed, giving the entire processing pattern circular polarization characteristics or elliptical polarization characteristics.

5. 2. The method for laser processing ultra-hard materials according to claim 1, which is applied to a machining device and processes the ultra-hard material to form a tool cutting edge.

6. 2. An apparatus for performing the method for laser processing of ultra-hard materials according to claim 1, comprising: a laser light source that generates a laser beam; a reflector that changes the direction of the laser beam; a focusing lens that receives the incident laser beam and forms a focused light spot; a galvanometer that controls the scanning range of the focused light spot; and a polarization driving device that changes the polarization azimuth angle of the emitted laser.

7. 7. The apparatus of claim 6, wherein the reflector is attached to an optical adjustment frame or a galvanometer to change the scanning direction of the focused light spot as needed to form the processing pattern.

8. 7. The apparatus of claim 6, wherein the focusing lens comprises a multi-lens field lens.

9. A machining device comprising an apparatus according to claim 8.

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