Laser three-dimensional precision machining method for hard and brittle materials

Abstract

The invention relates to a laser three-dimensional precision machining method for a hard and brittle material. The laser three-dimensional precision machining method comprises the steps that a hard and brittle material sample piece to be machined is placed on a machining platform and fixed; the laser source is controlled to emit laser, and an outer contour groove with a preset depth is ablated in the front face of the hard and brittle material sample piece; controlling a laser source to emit laser, modifying the bottom surface of the outer contour groove, physically separating the modified bottom surface of the outer contour groove from the whole hard and brittle material sample piece, and forming a hole; and controlling the laser source to emit laser and carrying out modification and physical separation on the peripheral area of the hole in the back surface so as to form a convex three-dimensional shape on the back surface. The laser source is used for sequentially completing two different processes of uniform ablation cutting and internal comprehensive modification of the glass material by adjusting parameters, so that the uniformity of the modification effect and the quality of splinters are improved, the integration of equipment and the continuity of the process are realized, and the production efficiency is improved on the basis of ensuring the processing precision.

Description

Technical Field

[0001] This invention relates to the field of laser precision machining technology, and more specifically, to a laser three-dimensional precision machining method for hard and brittle materials. Background Technology

[0002] In the precision cutting of brittle materials, especially glass covers for electronic devices, effectively avoiding and controlling stress concentration is a core indicator of the advancement of processing technology. The traditionally widely used diamond wheel cutting technology, a typical mechanical contact process, essentially achieves material separation by deliberately creating localized stress concentrations. This technology uses a high-hardness wheel to scratch the glass surface, generating micro-cracks as guides, and then applies mechanical bending stress to promote crack propagation and separation. However, this method of "forcibly" splitting the material by relying on macroscopic mechanical force has a fundamental flaw: the coarseness and randomness of stress control. The stress generated during scratching and cleaving inevitably concentrates at the tool mark defects, leading to edge chipping and subsurface micro-cracks at the cut edges. These geometrically sharp defects, as natural stress concentration points, significantly weaken the material's mechanical properties. In subsequent processing or use, any minor external load or thermal shock can cause the stress to amplify dramatically at these defect tips, triggering uncontrolled crack propagation and resulting in a decrease in the mechanical strength of the glass component. Therefore, traditional mechanical cutting faces severe challenges in modern electronic manufacturing that pursues high precision and high reliability.

[0003] To fundamentally solve the problems of processing defects and performance degradation caused by stress concentration, laser processing technology, especially laser-modified cutting, offers a revolutionary solution. The advancement of this technology lies in its paradigm shift from "mechanical force destruction" to "controlled energy separation." Its core principle is the selective modification effect of short-pulse lasers. This process introduces almost no macroscopic mechanical stress, thus preventing random edge chipping and microcracks from the outset.

[0004] More importantly, laser technology not only avoids the generation of stress concentration sources but also proactively optimizes and manages edge stress. This is manifested in two aspects: First, the original edge obtained by laser cutting itself has extremely high smoothness and integrity, eliminating sharp defects. Second, as an independent subsequent process, laser engraving technology can be used to process precise rounded chamfers on the cut edge. This design fundamentally changes the stress state of the edge by replacing sharp corners with smooth, continuous curved surfaces, allowing external loads to be evenly distributed along a smooth contour line, thereby minimizing the stress concentration factor.

[0005] In summary, laser processing technology, with its non-contact, high-precision, and programmable characteristics, not only overcomes the edge quality and strength problems caused by uncontrollable stress concentration in traditional methods, but also empowers and enhances the mechanical properties of components through proactive geometric optimization, making it an indispensable cornerstone process for the manufacturing of high-end electronic glass devices. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a laser three-dimensional precision machining method for hard and brittle materials, which addresses the shortcomings of the prior art.

[0007] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A laser three-dimensional precision machining method for hard and brittle materials, comprising the following steps:

[0008] S1. Place the hard and brittle material sample to be processed on the processing platform and fix it in place;

[0009] S2. Control the laser source to emit laser according to preset parameters, enter from the back of the hard and brittle material sample, focus on the front surface of the hard and brittle material sample, scan along the preset outer contour line on the front of the hard and brittle material sample, and ablate the outer contour groove with a preset depth on the front of the hard and brittle material sample.

[0010] S3: Control the laser source to emit laser according to preset parameters, the laser is incident from the back of the hard and brittle material sample and focused at the bottom of the outer contour groove, and the bottom surface of the outer contour groove is modified, and the modified bottom surface of the outer contour groove is physically separated from the hard and brittle material sample as a whole to form a hole.

[0011] S4: Control the laser source to emit laser according to preset parameters, and the laser is incident from the back of the hard and brittle material sample, focusing on the preset depth of the outer periphery of the hole, modifying and physically separating the outer periphery of the hole, so as to form a raised three-dimensional shape on the back of the hard and brittle material sample.

[0012] The beneficial effects of this invention are as follows: The laser three-dimensional precision machining method for hard and brittle materials of this invention involves irradiating the back of a hard and brittle material sample with a laser and ablating an outer contour groove with a preset depth on the front of the sample. Laser modification is then performed on the bottom of the middle region of the outer contour, followed by physical separation to form a cavity. The outer periphery of the cavity on the back of the sample is then modified and physically separated, forming a raised three-dimensional shape on the back of the sample. By adjusting parameters using a laser source, two distinct processes—uniform ablation and internal modification—are sequentially completed, improving the uniformity of the modification effect and the quality of the cleavage. This method achieves equipment integration and process continuity, significantly improving production efficiency while ensuring processing accuracy. It is suitable for large-scale production, avoids damage to the surface and internal structure of the glass material, and exhibits good adaptability and flexibility for different materials.

[0013] Based on the above technical solution, the present invention can be further improved as follows:

[0014] Further: In step S1, the step of placing the hard and brittle material sample to be processed on the processing platform and fixing it specifically includes the following steps:

[0015] S11: The drive mechanism places the hard and brittle material sample to be processed on the processing platform and fixes it using a preset fixing component;

[0016] S12: Use vision components to identify the outline of the hard and brittle material sample and the pre-set marker points on the hard and brittle material sample to determine the initial position and angular deviation of the hard and brittle material sample in the processing coordinate system.

[0017] S13: Perform angular deviation compensation based on the initial position and angular deviation of the hard and brittle material sample in the machining coordinate system, so that the contour of the compensated hard and brittle material sample is completely aligned with the pre-set mark points on the hard and brittle material sample and the machining coordinate system.

[0018] The beneficial effect of the above-mentioned further solution is that by identifying the initial position and angular deviation of the hard and brittle material sample in the machining coordinate system and compensating for it, a unified machining datum can be guaranteed, thus ensuring machining accuracy.

[0019] Further: In step S2, controlling the laser source to emit laser light according to preset parameters to irradiate the back side of the hard and brittle material sample, scanning along the preset outer contour line on the back side of the hard and brittle material sample, and ablating an outer contour groove with a preset depth on the front side of the hard and brittle material sample specifically includes the following steps:

[0020] S21: Control the laser source to emit a first laser according to the preset first processing parameters. The first laser is incident from the back of the hard and brittle material sample and focused to the front.

[0021] S22: Control the first laser to scan layer by layer along the preset outer contour line from the back of the hard and brittle material sample to form an outer contour groove with a preset depth on the front of the hard and brittle material sample.

[0022] The beneficial effect of the above-mentioned further scheme is that by controlling the first laser to be incident from the back of the hard and brittle material sample and focused on the front, the front of the hard and brittle material sample can be gradually ablated layer by layer at the position corresponding to the preset outer contour line during the scanning process of the first laser, and finally forming an outer contour groove of a preset depth, so as to facilitate subsequent modification and physical separation of the bottom of the outer contour groove.

[0023] Further: Before the first laser is incident on the back side of the hard and brittle material sample, the following steps are also included:

[0024] Further: In step S3, the controlled laser source emits laser light according to preset parameters and irradiates the back side of the hard and brittle material sample, and modifies the bottom surface of the outer contour groove. The modified bottom surface of the outer contour groove is then physically separated from the hard and brittle material sample to form a hole. This specifically includes the following steps:

[0025] S31: Control the laser source to emit a second laser according to the preset second processing parameters. The second laser irradiates the bottom surface of the outer contour groove from the back of the hard and brittle material sample, and modifies the area corresponding to the bottom of the outer contour groove to form a first modified area with multiple closely arranged modification lines.

[0026] S32: Based on the modified line, the bottom surface of the outer contour groove is physically separated from the hard and brittle material sample to form a hole.

[0027] The beneficial effect of the above-mentioned further solution is that the bottom surface of the outer contour groove is modified by the second laser to form a modification line, so that the bottom surface of the outer contour groove can be physically separated from the hard and brittle material sample by physical or chemical means, ensuring the separation quality and accuracy.

[0028] Further: Before the second laser irradiates the bottom surface of the outer contour groove, the following step is also included:

[0029] S30: The second laser is shaped and aberration corrected, and a multi-beam matrix distribution with multiple points is generated.

[0030] The beneficial effects of the above-mentioned further scheme are: by shaping and correcting the spherical aberration of the second laser through a beam shaper to form a matrix distribution of multiple laser beams with multiple points, the second laser can form a multi-focal beam, which improves the scanning etching efficiency. At the same time, spherical aberration correction can make the focal spot smaller and rounder, which is conducive to the lateral propagation of cracks and reduces the longitudinal propagation of cracks, thereby improving the physical separation quality and accuracy.

[0031] Further: In step S32, the physical separation of the bottom surface of the outer contour groove from the hard and brittle material sample based on the modified line to form a hole specifically includes the following steps:

[0032] S321a, Thermal stress pre-cracking:

[0033] A carbon dioxide laser beam is controlled to perform non-contact scanning heating on the first modified region containing the modified line. Due to the high absorption rate of laser energy in the modified region, the region rapidly heats up and expands. At the same time, inert gas is sprayed around it for rapid cooling. This process creates an extremely high temperature gradient between the first modified region and the surrounding region, and generates directional tensile stress at the boundary of the modified line to drive the existing initial microcracks inside the modified line to stably propagate along a predetermined path.

[0034] S322a, Ultrasonic-assisted dilation:

[0035] After the thermal stress pre-crack further expands the crack, the ultrasonic generator is driven to output high-frequency vibration energy that is compatible with the hard and brittle material sample, so that the hard and brittle material sample as a whole undergoes forced vibration. Under the action of high-frequency alternating load, the material in the crack tip area will undergo fatigue effect, so that the crack can continue to expand forward in a controllable manner until it penetrates to the bottom surface of the outer contour groove.

[0036] S323a, Separation complete:

[0037] Once the crack has completely penetrated the path of the modified material, the material inside the outer contour groove separates from the hard and brittle material sample as a whole, forming a hole.

[0038] The beneficial effects of the above-mentioned further scheme are as follows: by using a carbon dioxide laser beam to perform non-contact scanning heating on the first modified region containing the modified line, tensile stress can be formed in the first modified region. Combined with the ultrasonic generator driving the hard and brittle material sample to vibrate at high frequency, micro-stress concentration and fatigue effects are generated, causing the microcracks existing at the modified line to continuously expand under stress. Finally, the part in the outer contour groove is perfectly separated from the whole hard and brittle material sample. The cracks expand smoothly throughout the process, avoiding irregular fractures caused by thermal shock. The segmentation efficiency is high and the force is uniform.

[0039] Further: In step S32, the physical separation of the bottom surface of the outer contour groove from the hard and brittle material sample based on the modified line to form a hole specifically includes the following steps:

[0040] S321b: Heating a hard and brittle material sample to cause the sample to expand as a whole;

[0041] S322b: The first modified region containing the modified line is instantaneously cooled by a cooling medium. During this process, the cooled first modified region contracts rapidly, generating tensile stress within the first modified region and driving cracks to propagate stably along the modified path, ultimately separating the portion within the outer contour groove from the overall hard and brittle material sample.

[0042] The beneficial effects of the above-mentioned further scheme are: by heating and expanding the hard and brittle material sample, and then using a cooling medium to instantly cool the first modified region where the modified line is located, the tensile stress at the modified line is generated by utilizing the thermal expansion and contraction characteristics of the material, thereby achieving precise physical separation. The cost is relatively low and the applicability is wide.

[0043] Further: In step S4, the control of the laser source to emit laser light according to preset parameters and irradiate the outer periphery of the hole on the back side of the hard and brittle material sample for modification and physical separation, so as to form a raised three-dimensional shape on the back side of the hard and brittle material sample, specifically includes the following steps:

[0044] S41: Control the laser source to emit a third laser according to the preset third processing parameters. The laser is incident from the back of the hard and brittle material sample and focused at a preset depth in the peripheral area of ​​the hole. The peripheral area of ​​the hole is modified to form a second modified area with multiple closely arranged modification lines.

[0045] S42: Based on the modified line, the outer periphery of the hole on the back side of the hard and brittle material sample is physically separated from the whole hard and brittle material sample to form a raised three-dimensional shape on the back side of the hard and brittle material sample.

[0046] The beneficial effect of the above-mentioned further scheme is that by irradiating the outer periphery of the hole on the back side of the hard and brittle material sample with a third laser and modifying it, a continuous and complete modified layer network can be formed inside the outer periphery of the hole on the back side of the hard and brittle material sample. Then, the outer periphery of the hole on the back side of the hard and brittle material sample is physically separated from the hard and brittle material sample as a whole, ensuring the accuracy and safety of the separation.

[0047] Further: In step S41, the connection between the inner and outer walls of the hole and the outer periphery of the hole on the back and front sides of the hard and brittle material sample is a continuous arc-shaped chamfer structure.

[0048] The beneficial effects of the above-mentioned further solution are as follows: by adjusting the third laser parameters and forming a continuous arc-shaped chamfer structure at the connection between the inner and outer walls of the hole and the outer periphery of the hole on the back and front sides of the hard and brittle material sample, the stress concentration phenomenon at the outer edge of the three-dimensional protrusion structure can be alleviated, a smooth transition with the base surface can be achieved, sharp geometric discontinuities can be eliminated, stress concentration can be effectively reduced, and thus the risk of brittle fracture caused by it can be significantly suppressed. Attached Figure Description

[0049] Figure 1 This is a schematic flowchart of a laser three-dimensional precision machining method for hard and brittle materials according to an embodiment of the present invention;

[0050] Figure 2This is a schematic diagram of the outer contour groove formed on a hard and brittle material sample according to an embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of the structure of a hole formed in a hard and brittle material sample according to an embodiment of the present invention;

[0052] Figure 4 This is a schematic diagram of a protrusion formed on a hard and brittle material sample according to an embodiment of the present invention. Detailed Implementation

[0053] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0054] In embodiments of the present invention, the hard and brittle materials may be glass, sapphire, and fused silica, which are widely used in consumer electronics products and have high requirements for processing precision and quality.

[0055] like Figure 1 As shown, a laser three-dimensional precision machining method for hard and brittle materials includes the following steps:

[0056] S1. Place the hard and brittle material sample to be processed on the processing platform and fix it in place;

[0057] S2. Control the laser source to emit laser according to preset parameters, enter from the back of the hard and brittle material sample, focus on the front surface of the hard and brittle material sample, scan along the preset outer contour line on the front of the hard and brittle material sample, and ablate the outer contour groove with a preset depth on the front of the hard and brittle material sample.

[0058] S3: Control the laser source to emit laser according to preset parameters, the laser is incident from the back of the hard and brittle material sample and focused at the bottom of the outer contour groove, and the bottom surface of the outer contour groove is modified, and the modified bottom surface of the outer contour groove is physically separated from the hard and brittle material sample as a whole to form a hole.

[0059] S4: Control the laser source to emit laser according to preset parameters, and the laser is incident from the back of the hard and brittle material sample, focusing on the preset depth of the outer periphery of the hole, modifying and physically separating the outer periphery of the hole, so as to form a raised three-dimensional shape on the back of the hard and brittle material sample.

[0060] The laser three-dimensional precision machining method for hard and brittle materials of the present invention involves irradiating the back of a hard and brittle material sample with a laser and ablating an outer contour groove of a predetermined depth on the front of the sample. Laser modification is then performed on the bottom of the middle region of the outer contour, followed by physical separation to form a cavity. The outer periphery of the cavity on the back of the sample is then modified and physically separated, forming a raised three-dimensional shape on the back of the sample. Using a laser source, parameters are adjusted to sequentially complete two distinct processes: uniform ablation and cutting of the glass material, and comprehensive internal modification. This improves the uniformity of the modification effect and the quality of the cleavage, achieving equipment integration and process continuity. While ensuring processing accuracy, it significantly improves production efficiency, is suitable for large-scale production, avoids damage to the surface and internal structure of the glass material, and has good adaptability and flexibility for different materials.

[0061] In one or more embodiments of the present invention, step S1, which involves placing the hard and brittle material sample to be processed on the processing platform and fixing it, specifically includes the following steps:

[0062] S11: The drive mechanism places the hard and brittle material sample to be processed on the processing platform and fixes it using a preset fixing component;

[0063] Here, the flat sample to be processed is taken out of the material box by a robotic arm or conveyor belt and transferred to the vacuum suction cup or precision fixture of the processing platform. The vacuum adsorption system is activated to fix the flat sample firmly and flat, preventing displacement during processing.

[0064] S12: Use vision components to identify the outline of the hard and brittle material sample and the pre-set marker points on the hard and brittle material sample to determine the initial position and angular deviation of the hard and brittle material sample in the processing coordinate system.

[0065] Here, a high-resolution CCD vision sensor is used to identify the basic outline of the sample or pre-made marker points to determine the initial position and angular deviation of the hard and brittle material sample in the processing coordinate system. The specific identification process is existing technology and will not be elaborated here.

[0066] S13: Perform angular deviation compensation based on the initial position and angular deviation of the hard and brittle material sample in the machining coordinate system, so that the contour of the compensated hard and brittle material sample is completely aligned with the pre-set mark points on the hard and brittle material sample and the machining coordinate system.

[0067] By identifying and compensating for the initial position and angular deviation of hard and brittle material samples in the machining coordinate system, a unified machining datum can be ensured, thus guaranteeing machining accuracy.

[0068] In one or more embodiments of the present invention, step S2, controlling the laser source to emit laser light according to preset parameters to irradiate the back side of the hard and brittle material sample, scanning along the preset outer contour line on the back side of the hard and brittle material sample, and ablating an outer contour groove with a preset depth on the front side of the hard and brittle material sample, specifically includes the following steps:

[0069] S21: Control the laser source to emit a first laser according to the preset first processing parameters. The first laser is incident from the back of the hard and brittle material sample and focused to the front.

[0070] Here, the first processing parameters include the laser wavelength in the range of [355nm, 1064nm], the pulse width in the range of [100fs, 30ns], and the repetition frequency in the range of [50kHz, 5000kHz].

[0071] S22: Control the first laser to scan layer by layer along the preset outer contour line from the back of the hard and brittle material sample, so as to form an outer contour groove with a preset depth on the front of the hard and brittle material sample, such as... Figure 2 As shown.

[0072] In embodiments of the invention, the outer contour is intentionally designed as a circular arc transition shape with a predetermined radius of curvature, rather than a right-angle configuration. This design aims to eliminate severe stress concentration caused by sharp corners. The smooth geometric transition achieved through laser processing effectively reduces the stress concentration factor, allowing external loads to be evenly distributed along the contour, thereby significantly improving the fatigue resistance and mechanical reliability of the component.

[0073] The control system precisely positions the laser beam focus on the upper surface of the sample according to a preset outer contour line. Specifically, the laser beam scans and ablates along the outer contour line of the groove on the front side of the sample, removing material layer by layer until the set groove depth is reached. During the scanning process, the focus of the first laser is dynamically controlled, and the laser's focusing position is adjusted in real time according to the undulations of the sample surface to ensure uniform etching depth.

[0074] It should be noted that, in the embodiments of the present invention, during this scanning ablation process, a blowing / suction device is used to simultaneously blow away / suction away the debris generated by the etching, keeping the processing area clean.

[0075] By controlling the first laser to enter from the back of the hard and brittle material sample and focus it to the front, the front of the hard and brittle material sample can be gradually ablated layer by layer at the position corresponding to the preset outer contour line during the scanning process of the first laser, and finally forming an outer contour groove of a preset depth, so as to facilitate subsequent modification and physical separation of the bottom of the outer contour groove.

[0076] Specifically, after scanning and ablation to the set depth of the outer contour groove, the depth, width, and contour clarity of the outer contour groove are detected online again using a CCD vision sensor or a laser displacement sensor to ensure processing quality.

[0077] In one or more embodiments of the present invention, step S3, in which the laser source is controlled to emit laser light according to preset parameters and irradiate the back side of the hard and brittle material sample, and the bottom surface of the outer contour groove is modified, and the modified bottom surface of the outer contour groove is physically separated from the hard and brittle material sample to form a hole, specifically includes the following steps:

[0078] S31: Control the laser source to emit a second laser according to the preset second processing parameters. The second laser irradiates the bottom surface of the outer contour groove from the back of the hard and brittle material sample, and modifies the area corresponding to the bottom of the outer contour groove to form a first modified area with multiple closely arranged modification lines.

[0079] Here, the second processing parameters include the laser wavelength in the range of [355nm, 1064nm], the pulse width in the range of [100fs, 30ns], and the repetition frequency in the range of [50kHz, 5000kHz].

[0080] The second laser scans the bottom of the groove, forming multiple closely spaced modification lines. During this process, the laser energy is selectively absorbed by the material, and through nonlinear effects such as multiphoton absorption, modification is induced in the focal region within the material.

[0081] In particular, in embodiments of the present invention, a real-time monitoring system is introduced to detect the optical characteristics of the modified region and adjust laser parameters, such as pulse energy, to achieve the best modification effect.

[0082] S32: Based on the modified line, the bottom surface of the outer contour groove is physically separated from the entire hard and brittle material sample to form a hole, such as... Figure 3 As shown.

[0083] The bottom surface of the outer contour groove is modified by a second laser to form a modification line. This allows the bottom surface of the outer contour groove to be physically separated from the hard and brittle material sample by physical or chemical means, ensuring separation quality and accuracy.

[0084] Optionally, before the second laser irradiates the bottom surface of the outer contour groove, the following step is further included:

[0085] S30: The second laser is shaped and aberration corrected, and a multi-beam matrix distribution with multiple points is generated.

[0086] By shaping and correcting the spherical aberration of the second laser beam through a beam shaper to form a matrix of multiple laser beams arranged at multiple points, the second laser beam can form a multi-focal beam, improving the scanning etching efficiency. At the same time, spherical aberration correction can make the focal spot smaller and rounder, which is beneficial to the lateral propagation of cracks and reduces the longitudinal propagation of cracks, thereby improving the physical separation quality and accuracy.

[0087] Optionally, in one or more embodiments of the present invention, step S32, which involves physically separating the bottom surface of the outer contour groove from the entire hard and brittle material sample based on the modified line to form a hole, specifically includes the following steps:

[0088] S321a, Thermal stress pre-cracking:

[0089] A carbon dioxide laser beam is controlled to perform non-contact scanning heating on the first modified region containing the modified line. Due to the high absorption rate of laser energy in the modified region, the region heats up rapidly and attempts to expand. At the same time, inert gas is sprayed around it for rapid cooling. This process creates an extremely high temperature gradient between the modified region and the surrounding region, thereby generating huge directional tensile stress at the boundary of the modified line, especially at the front end along the predetermined cutting path. This tensile stress drives the existing initial microcracks inside the modified line to propagate stably along the predetermined path.

[0090] S322a, Ultrasonic-assisted dilation:

[0091] After the thermal stress pre-crack further expands the crack, the ultrasonic generator is driven to output high-frequency vibration energy adapted to the hard and brittle material sample, causing the entire sample to undergo forced vibration. Due to the natural stress concentration at the crack tip generated by the pre-crack, the material in the crack tip region will undergo fatigue effect under the action of high-frequency alternating load. This allows the crack to continue to expand forward in a controllable manner until it penetrates to the bottom surface of the outer contour groove. This method utilizes the dynamic fatigue characteristics of the material, rather than a single impact, so it can effectively avoid the unstable expansion of cracks and achieve more precise separation.

[0092] S323a, Separation complete:

[0093] Once the crack has completely penetrated the path of the modified material, the material inside the outer contour groove separates from the hard and brittle material sample as a whole, forming a hole.

[0094] Here, the wavelength of the carbon dioxide laser beam is typically 10.6 μm. Taking advantage of the high absorption rate of carbon dioxide laser beams by hard and brittle materials (such as glass), non-contact scanning heating is performed on the modified region containing the modification line. When the tensile stress generated inside the material exceeds the strength limit of the material after laser modification, cracks will initiate from the modified layer and propagate perfectly along the modification line, which is beneficial for the separation of the sample.

[0095] It is important to note that control is necessary. The laser beam spot size, power, and scanning speed ensure uniform heat application along the modification line, guaranteeing smooth crack propagation and preventing irregular fractures caused by thermal shock. This method is clean, non-contact, and extremely fast, making it suitable for large-scale production. Similarly, precise control of the ultrasonic frequency, amplitude, and duration is required to ensure that vibrational energy is accurately concentrated on the modification line. This method offers high segmentation efficiency and uniform force application.

[0096] The first modified region containing the modified line is non-contactly scanned and heated by a carbon dioxide laser beam, which creates tensile stress in the first modified region. When the sample is driven by a high-frequency mechanical vibration of an ultrasonic generator, micro-stress concentration and fatigue effects are generated, causing the microcracks at the modified line to continuously expand under stress. Finally, the part in the outer contour groove is perfectly separated from the whole hard and brittle material sample. The cracks expand smoothly throughout the process, avoiding irregular fractures caused by thermal shock. The segmentation efficiency is high and the force is uniform.

[0097] Optionally, in one or more embodiments of the present invention, step S32, which involves physically separating the bottom surface of the outer contour groove from the entire hard and brittle material sample based on the modified line to form a hole, specifically includes the following steps:

[0098] S321b: Heating a hard and brittle material sample to cause the sample to expand as a whole;

[0099] S322b: A cooling medium is used to rapidly cool the heated first modified region containing the modified lines. During this process, the cooled first modified region attempts to contract rapidly, but its contraction behavior is strongly constrained by the surrounding relatively low-temperature and rigid region. This resistance to contraction generates high tensile stress in the first modified region (especially at the fragile modified lines). When this tensile stress exceeds the fracture strength of the material, it drives the crack to propagate steadily along the modified path, eventually separating the part within the outer contour groove from the overall sample.

[0100] Here, it can be divided into two modes: "global heating-local cooling" or "local heating-local cooling". The key control parameters include heating temperature, cooling medium temperature, flow rate and injection time.

[0101] By heating and expanding a hard and brittle material sample, and then using a cooling medium to rapidly cool the first modified region where the modified line is located, the thermal expansion and contraction properties of the material are utilized to generate a corresponding degree of tensile stress at the modified line, thereby achieving precise physical separation. This method is relatively low in cost and has wide applicability.

[0102] In one or more embodiments of the present invention, step S4, in which the laser source is controlled to emit laser light according to preset parameters and irradiate the outer periphery of the hole on the back side of the hard and brittle material sample for modification and physical separation, so as to form a raised three-dimensional shape on the back side of the hard and brittle material sample, specifically includes the following steps:

[0103] S41: Control the laser source to emit a third laser according to the preset third processing parameters. The laser is incident from the back of the hard and brittle material sample and focused at a preset depth in the peripheral area of ​​the hole. The peripheral area of ​​the hole is modified to form a second modified area with multiple closely arranged modification lines.

[0104] Here, the third processing parameters include the laser wavelength in the range of [355nm, 1064nm], the pulse width in the range of [100fs, 30ns], and the repetition frequency in the range of [50kHz, 5000kHz]. At the same time, an air blowing / suction device is introduced to help remove the debris generated during etching, reduce secondary contamination of the etched surface by the debris, and improve the etching quality.

[0105] It should be noted that the focusing depth of the third laser needs to be lower than the height of the back edge of the hole, so that after the outer periphery of the hole on the back of the hard and brittle material sample is physically separated from the whole hard and brittle material sample, a protrusion is formed at the hole location.

[0106] S42: Based on the modified line, the outer periphery region of the hole on the back side of the hard and brittle material sample is physically separated from the entire hard and brittle material sample to form a raised three-dimensional shape on the back side of the hard and brittle material sample, such as... Figure 4 As shown.

[0107] By irradiating the outer periphery of the holes on the back side of the hard and brittle material sample with a third laser and modifying it, a continuous and complete modified layer network can be formed inside the outer periphery of the holes on the back side of the hard and brittle material sample. Then, the outer periphery of the holes on the back side of the hard and brittle material sample is physically separated from the hard and brittle material sample as a whole, ensuring the accuracy and safety of the separation.

[0108] Optionally, in one or more embodiments of the present invention, in step S41, the connection between the inner and outer walls of the hole and the outer peripheral area of ​​the hole on the back and front sides of the hard and brittle material sample respectively has a continuous arc chamfer structure.

[0109] By adjusting the third laser parameters and forming a continuous arc-shaped chamfer structure at the connection between the inner and outer walls of the hole and the outer periphery of the hole on the back and front sides of the hard and brittle material sample, the stress concentration phenomenon at the outer edge of the three-dimensional protrusion structure can be alleviated, a smooth transition with the base surface can be achieved, sharp geometric discontinuities can be eliminated, stress concentration can be effectively reduced, and thus the risk of brittle fracture caused by it can be significantly suppressed.

[0110] The hard and brittle material of this invention can be widely used in consumer electronics products such as smartphones, tablets, and touchscreens as their back panels. Since these consumer electronics products have very high requirements for the processing precision and quality of the glass back panels, the laser three-dimensional precision machining method of this invention can meet the needs of these electronic products for glass back panels, greatly improving the processing quality of the glass back panels and reducing the recycling and reuse costs of the glass back panels. It has broad market demand and good application prospects.

[0111] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A laser three-dimensional precision machining method for hard and brittle materials, characterized in that, Includes the following steps: S1. Place the hard and brittle material sample to be processed on the processing platform and fix it in place; S2. Control the laser source to emit laser according to preset parameters, enter from the back of the hard and brittle material sample, focus on the front surface of the hard and brittle material sample, scan along the preset outer contour line on the front of the hard and brittle material sample, and ablate the outer contour groove with a preset depth on the front of the hard and brittle material sample. S3: Control the laser source to emit laser according to preset parameters, the laser is incident from the back of the hard and brittle material sample and focused at the bottom of the outer contour groove, and the bottom surface of the outer contour groove is modified, and the modified bottom surface of the outer contour groove is physically separated from the hard and brittle material sample as a whole to form a hole. S4: Control the laser source to emit laser according to preset parameters, and the laser is incident from the back of the hard and brittle material sample, focusing on the preset depth of the outer periphery of the hole, modifying and physically separating the outer periphery of the hole, so as to form a raised three-dimensional shape on the back of the hard and brittle material sample.

2. The laser three-dimensional precision machining method for hard and brittle materials according to claim 1, characterized in that, Includes the following steps: Step S1, which involves placing the hard and brittle material sample to be processed on the processing platform and fixing it, specifically includes the following steps: S11: The drive mechanism places the hard and brittle material sample to be processed on the processing platform and fixes it using a preset fixing component; S12: Use vision components to identify the outline of the hard and brittle material sample and the pre-set marker points on the hard and brittle material sample to determine the initial position and angular deviation of the hard and brittle material sample in the processing coordinate system. S13: Perform angular deviation compensation based on the initial position and angular deviation of the hard and brittle material sample in the machining coordinate system, so that the contour of the compensated hard and brittle material sample is completely aligned with the pre-set mark points on the hard and brittle material sample and the machining coordinate system.

3. The laser three-dimensional precision machining method for hard and brittle materials according to claim 1, characterized in that, In step S2, the laser source is controlled to emit laser light according to preset parameters to irradiate the back side of the hard and brittle material sample, scan along the preset outer contour line on the back side of the hard and brittle material sample, and ablate an outer contour groove with a preset depth on the front side of the hard and brittle material sample. Specifically, this includes the following steps: S21: Control the laser source to emit a first laser according to the preset first processing parameters. The first laser is incident from the back of the hard and brittle material sample and focused to the front. S22: Control the first laser to scan layer by layer along the preset outer contour line from the back of the hard and brittle material sample to form an outer contour groove with a preset depth on the front of the hard and brittle material sample.

4. The laser three-dimensional precision machining method for hard and brittle materials according to claim 1, characterized in that, In step S3, the controlled laser source emits laser light according to preset parameters and irradiates the back side of the hard and brittle material sample, and modifies the bottom surface of the outer contour groove. The modified bottom surface of the outer contour groove is then physically separated from the hard and brittle material sample to form a hole. Specifically, this includes the following steps: S31: Control the laser source to emit a second laser according to the preset second processing parameters. The second laser irradiates the bottom surface of the outer contour groove from the back of the hard and brittle material sample, and modifies the area corresponding to the bottom of the outer contour groove to form a first modified area with multiple closely arranged modification lines. S32: Based on the modified line, the bottom surface of the outer contour groove is physically separated from the hard and brittle material sample to form a hole.

5. The laser three-dimensional precision machining method for hard and brittle materials according to claim 4, characterized in that, Before the second laser irradiates the bottom surface of the outer contour groove, the following steps are also included: S30: The second laser is shaped and aberration corrected, and a multi-beam matrix distribution with multiple points is generated.

6. The laser three-dimensional precision machining method for hard and brittle materials according to claim 4, characterized in that, In step S32, the physical separation of the bottom surface of the outer contour groove from the hard and brittle material sample based on the modified line to form a hole specifically includes the following steps: S321a, Thermal stress pre-cracking: A carbon dioxide laser beam is controlled to perform non-contact scanning heating on the first modified region containing the modified line. Due to the high absorption rate of laser energy in the modified region, the region rapidly heats up and expands. At the same time, inert gas is sprayed around it for rapid cooling. This process creates an extremely high temperature gradient between the first modified region and the surrounding region, and generates directional tensile stress at the boundary of the modified line to drive the existing initial microcracks inside the modified line to stably propagate along a predetermined path. S322a, Ultrasonic-assisted fracturing: After the thermal stress pre-crack further expands the crack, the ultrasonic generator is driven to output high-frequency vibration energy that is compatible with the hard and brittle material sample, so that the hard and brittle material sample as a whole undergoes forced vibration. Under the action of high-frequency alternating load, the material in the crack tip area will undergo fatigue effect, so that the crack can continue to expand forward in a controllable manner until it penetrates to the bottom surface of the outer contour groove. S323a, Separation complete: Once the crack has completely penetrated the path of the modified material, the material inside the outer contour groove separates from the hard and brittle material sample as a whole, forming a hole.

7. The laser three-dimensional precision machining method for hard and brittle materials according to claim 4, characterized in that, In step S32, the physical separation of the bottom surface of the outer contour groove from the hard and brittle material sample based on the modified line to form a hole specifically includes the following steps: S321b: Heating a hard and brittle material sample to cause the sample to expand as a whole; S322b: The first modified region containing the modified line is rapidly cooled by a cooling medium. During this process, the cooled first modified region contracts sharply, generating tensile stress in the first modified region and driving the crack to propagate steadily along the modified path, eventually separating the part in the outer contour groove from the whole hard and brittle material sample.

8. The laser three-dimensional precision machining method for hard and brittle materials according to any one of claims 1-7, characterized in that, In step S4, the controlled laser source emits laser light according to preset parameters and irradiates the outer periphery of the hole on the back side of the hard and brittle material sample to perform modification and physical separation, so as to form a raised three-dimensional shape on the back side of the hard and brittle material sample. Specifically, this includes the following steps: S41: Control the laser source to emit a third laser according to the preset third processing parameters. The laser is incident from the back of the hard and brittle material sample and focused at a preset depth in the peripheral area of ​​the hole. The peripheral area of ​​the hole is modified to form a second modified area with multiple closely arranged modification lines. S42: Based on the modified line, the outer periphery of the hole on the back side of the hard and brittle material sample is physically separated from the whole hard and brittle material sample to form a raised three-dimensional shape on the back side of the hard and brittle material sample.

9. The laser three-dimensional precision machining method for hard and brittle materials according to claim 8, characterized in that, In step S41, the connection between the inner and outer walls of the hole and the outer periphery of the hole on the back and front sides of the hard and brittle material sample is a continuous arc-shaped chamfer structure.

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