Laser drilling method

Abstract

The present invention provides a laser drilling method, comprising the following steps: S1: determining workpiece positioning and target aperture; S2: determining workpiece rotation speed and protective gas flow direction; S3: determining laser power, laser frequency, scanning speed, laser beam focus motion diameter, and zoom increment; S4: determining the laser incident angle; and S5: drilling using the above-determined processing parameters. The laser drilling method provided by the present invention can improve drilling efficiency, improve drilling quality, significantly reduce taper, and achieve the preparation of holes of various tapers through posture adjustment.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling, in particular to a laser drilling method. Background Art

[0002] Deep micro-hole machining, a core technology in the aerospace industry, is widely used in the machining of critical components such as turbine blade film cooling holes, fuel injection micro-holes, and satellite propulsion system orifice plates. These components typically consist of arrays of micro-holes at the millimeter or submillimeter scale. The continuous expansion of applications and the deterioration of service environments have placed dual demands on the efficiency and quality of deep micro-hole machining. Furthermore, the aspect ratio of holes is increasing, and complex geometries such as straight, tapered, and inclined are also being adopted.

[0003] This paper uses SiCf / SiC composites, which combine high specific strength, high specific stiffness, and excellent fatigue resistance, as an example. While ideal for heat-resistant components in advanced aeroengines, their high hardness, non-conductivity, and multiphase composite structure lead to a significant conflict between drilling efficiency and precision. (Mainstream drilling methods, such as mechanical machining, suffer from severe tool wear and delamination damage, while water jet machining is susceptible to material anisotropy that affects trajectory accuracy.) Against this backdrop, laser machining technology, with its non-contact processing mode, high-precision control capabilities, and unique applicability to non-conductive materials, has emerged as a preferred solution for high-quality deep microhole machining in difficult-to-machine materials like SiCf / SiC composites, and has proven successful in straight hole machining. However, with the continued expansion of SiCf / SiC composite applications and the increasing extremes of their service environments, the demand for microholes with large aspect ratios is growing, placing even higher demands on the coordinated optimization of processing efficiency and quality. Although extensive research has been devoted to optimizing the laser drilling process of SiCf / SiC composites and it provides many advantages in CMCs applications, when the material thickness exceeds 3 mm and the aspect ratio of the hole is greater than 6, the existing laser drilling technology still faces low hole production efficiency, poor quality, and large taper.

[0004] The laser incident angle is adjustable. In the prior art, once the aperture of a hole drilled by a three-dimensional galvanometer or a two-dimensional galvanometer is determined, the incident angle is fixed and cannot be adjusted. Only the angle of the workpiece can be adjusted. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a laser drilling method.

[0006] In order to achieve the above-mentioned purpose of the invention, the technical solution of the present invention is as follows:

[0007] A laser drilling method comprises the following steps:

[0008] S1: Workpiece positioning and determination of target aperture;

[0009] The laser beam layered drilling method is adopted. The drilling process is a double-circular rotation motion of the laser and the workpiece. That is, the laser beam is rotated by the galvanometer, and the workpiece is rotated around its center at the same time, so that the rotation of the laser beam focus and the rotation of the workpiece are carried out simultaneously in the same direction or opposite directions. The rotation trajectory of the laser beam focus is a closed figure. The ratio of the rotation angular velocity of the workpiece and the rotation angular velocity of the laser beam focus is an irrational number, which makes the scanning motion trajectory of the laser beam focus in each layer change randomly, thereby removing the ripples on the hole wall and improving the smoothness of the hole morphology.

[0010] S2: Determine the workpiece rotation speed and the direction of the protective gas flow;

[0011] The direction of the protective airflow is always from the unprocessed area to the processed area, and it is tilted to the laser processing position;

[0012] S3: Determine laser power, laser frequency, scanning speed, laser beam focus movement diameter, and zoom increment;

[0013] Laser power: within the power range given by the equipment, the maximum laser power is preferred;

[0014] Laser frequency: the laser frequency corresponding to the maximum power;

[0015] Laser scanning speed: The specific value of the laser beam focus scanning speed v is determined according to the drilling time and drilling quality. The scanning speed corresponding to the short drilling time and good drilling quality is selected. The drilling quality is obtained by the roundness and surface morphology of the hole. The smaller the roundness deviation and the smaller the degree of surface oxidation, the more ideal the drilling quality.

[0016] Laser beam focus movement diameter: The laser beam focus rotation movement diameter d1 can be smaller than the target aperture. To ensure processing efficiency, a smaller size is preferred;

[0017] Zoom increment: Provides different focus increments to compare laser drilling times at different focus increments. Select the scanning speed that results in the shortest drilling time and the best drilling quality, as determined by hole roundness and surface topography.

[0018] During the entire drilling process, the center distance between the laser beam focus rotation axis and the workpiece rotation axis remains unchanged; the relative positions of the workpiece center rotation axis and the laser beam focus trajectory rotation axis in space remain unchanged.

[0019] S4: Determine the laser incident angle;

[0020] The laser incident angle is adjustable, using a three-dimensional galvanometer to adjust the laser incident angle by changing the laser beam focal position;

[0021] S5: Drilling using the processing parameters determined above

[0022] When drilling starts, the rotation axis of the workpiece coincides with the rotation axis of the laser beam focus.

[0023] Preferably, the trajectories of both the rotation of the laser beam focus and the rotation of the workpiece are circles.

[0024] As a preferred embodiment, the relative positions of the central rotation axis of the workpiece and the rotation axis of the laser beam focal track in space remain unchanged, which means that the distance between the two remains unchanged and the directions are constant.

[0025] As a preferred method, the rotation of the laser beam and the rotation of the workpiece are in opposite directions, because the reverse effect is better, there is a relative speed difference, the relative speed difference is larger, and the energy distribution is more uniform.

[0026] As a preferred method, when determining parameters, the drilling position can be adjusted without affecting the hole diameter and hole taper, for example, by using a slide module.

[0027] As a preferred method, the duration of laser drilling refers to the time from the start to the end of drilling, and the duration is calculated using laser processing software or a method of photographing.

[0028] As a preferred method, the spatial and temporal distribution control of laser energy and energy distribution control are achieved through the rotation of the workpiece and the rotational movement of the laser beam focus. After achieving energy distribution control, the focus increment is further improved. After matching the focus increment in step S3, the drilling efficiency is improved.

[0029] In a laser drilling method proposed in the present invention, the energy distribution of the laser beam focus in the processing area is determined by the motion trajectory. The motion trajectory is analyzed as follows: the laser focus spot makes a circular motion with a radius of r (mm) in the counterclockwise direction and a motion speed of v (mm / s). The workpiece makes a rotational motion in the clockwise direction with a rotation speed of ω (revolutions / minute). The distance between the workpiece spin center and the center of the circular motion of the light spot is φ (mm). The laser is a pulsed laser with a pulse frequency of f (kHz). During the laser drilling process, the combined motion of the laser focus spot and the workpiece causes the light spot to form a specific trajectory on the workpiece surface. In order to describe this trajectory, a fixed reference coordinate system is set with the workpiece spin center Q as the origin of the coordinate system. The position of the laser focus spot in the fixed coordinate system is:

[0030]

[0031] in: ,“ " is the angular velocity of the laser spot motion trajectory, "t" is the processing time, " is the distance between the laser focus spot and the origin of the coordinate system on the x-axis," " is the distance between the laser focus spot and the origin of the coordinate system on the y-axis. The rotation angle of the workpiece for:

[0032]

[0033] in: , " " is the angular velocity of the workpiece rotation, and "-" indicates clockwise rotation. Therefore, the motion trajectory equation of the laser beam focus in the processing area is:

[0034]

[0035] in:" " is the distance between the laser beam focus and the origin of the coordinate system on the x-axis," ” is the distance between the laser beam focus and the origin of the coordinate system on the y-axis.

[0036] The laser is pulsed, with a pulse frequency of f (kHz), emitting a pulse every Δt = 1 / 1000f seconds. The laser processing process is performed at this interval. Based on the trajectory equation, it can be concluded that energy distribution can be controlled by adjusting the processing parameters.

[0037] As a preferred embodiment, in S3, the selection of the laser beam focus rotational motion diameter d1 also depends on the material thickness. When the material thickness is ≤3 mm, the diameter d1 / material thickness = 10 / 1; when the material thickness is ≥3 mm, the diameter d1 / material thickness = 5 / 1.

[0038] As a preferred method, in step S4 of the present invention, the laser incident angle is achieved by adjusting the processing position. In a two-dimensional galvanometer or other types of laser equipment, the laser incident angle can also be adjusted by adjusting the posture of the workpiece or the posture of the laser beam.

[0039] As a preferred embodiment, in step S3 of the present invention, the focus increment is the distance the laser focus descends. When the laser focus position cannot be changed, the focus increment is the distance the workpiece ascends.

[0040] The beneficial effects of the present invention are:

[0041] (1) The laser drilling method provided by the present invention can improve drilling efficiency. The drilling efficiency achieved is more than 30 times that of the same type of laser equipment and more than 7 times that of the current same type of holes. The drilling time is obtained by taking pictures with a high-speed camera, such as Figure 5 and Figure 6 .

[0042] (2) The laser drilling method provided by the present invention can improve the drilling quality. This is demonstrated by setting up a control experiment in which a conventional drilling process is used and the above method is used to determine the optimal parameters of the conventional drilling process. Figure 9 The conventional drilling method is demonstrated, showing the worst hole roundness and the largest taper. This is due to the fixed direction of the shielding gas flow, resulting in inconsistent heating and oxidation levels on the windward and leeward sides of the hole, resulting in both the inlet and outlet cross-sections being ellipses elongated along the direction of the gas flow. Furthermore, uneven heat accumulation creates an initial taper during the initial processing phase, which is then only slightly corrected by differences in absorptivity at different locations on the hole wall. The Gaussian energy distribution and fixed angle of incidence of the laser beam contribute to the extremely poor geometric accuracy of the finished hole. Figure 10 This paper demonstrates a laser drilling method provided by the present invention, which significantly optimizes the aperture morphology, achieving nearly perfect circular cross-sections at the aperture opening and bottom, and completely eliminating roundness deviation. This improvement is attributed to the combination of workpiece spin and the high-frequency rotational motion of the laser beam, which aligns the airflow direction with the processing position, ensuring continuous and spatially uniform energy input. Furthermore, the surface integrity of the hole wall demonstrates the effectiveness of the laser drilling method provided by the present invention in improving drilling quality. Figure 11 The quality of the hole wall produced by the conventional drilling method is demonstrated. There are obvious ripples, debris accumulation, cracks and other defects on the hole wall. The elemental analysis also shows a high degree of oxidation. Figure 12 The quality of the hole wall produced by a drilling method provided by the present invention is demonstrated. In comparison, the surface quality of the hole wall is significantly improved, the corrugation is suppressed, the oxygen content is low in elemental analysis, and the clear outline of the fiber bundle is visible.

[0043] (3) The laser drilling method provided by the present invention can significantly reduce the taper and realize the preparation of holes with various tapers by adjusting the posture. Figure 13 and Figure 14 The internal features of the holes made by the conventional hole making method and the laser drilling method provided by the present invention are shown. The taper of the hole made by the conventional hole making method is 0.14°, while the taper of the hole made by the laser drilling method provided by the present invention is 0.05°. Figure 15 The application of the laser drilling method provided by the present invention to other hole types is demonstrated, and it is possible to prepare different hole types such as straight holes without tapers, positive tapered holes, negative tapered holes, and inclined holes of various sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a laser drilling method step provided by the present invention.

[0045] Figure 2 This is a schematic diagram of a laser drilling method provided by the present invention.

[0046] Figure 3It is a schematic diagram of the laser spot motion trajectory.

[0047] Figure 4 It is the plume change of a laser drilling method provided by the present invention within one scanning cycle (within 0.6s).

[0048] Figure 5 It is the plume change of the conventional laser drilling method within one scanning cycle (within 0.6s).

[0049] Figure 6 It is a schematic diagram of the consistency between the shielding gas and the processing position.

[0050] Figure 7 This figure shows the effects of different scanning speeds (v, mm / s) and focus increment combinations on drilling time under a laser drilling process provided by the present invention. Only the parameters for successful drilling are marked in the figure, and those for unsuccessful drilling are not marked in the figure.

[0051] Figure 8 The laser drilling process provided by the present invention is photographed and measured using a high-speed camera to record the time.

[0052] Figure 9 It is the geometric shape of the hole entrance and exit in conventional drilling process.

[0053] Figure 10 It is the geometric shape of the hole entrance and exit of a drilling method provided by the present invention.

[0054] Figure 11 It is the hole wall quality of the hole made by conventional drilling method.

[0055] Figure 12 The present invention provides a drilling method to obtain hole wall quality.

[0056] Figure 13 It is the hole morphology of the conventional drilling method.

[0057] Figure 14 The invention provides a method for laser drilling a hole.

[0058] Figure 15 The invention provides a laser hole making method for application in micro-holes with different tapers, different angles and different scales. DETAILED DESCRIPTION

[0059] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0060] Figure 4 This is the plume variation during a single scan cycle (0.6 seconds) using a conventional laser drilling method. The plume is generally weak, with a strong plume appearing 0.4 seconds after the laser process begins. Furthermore, the plume initially increases and then decreases, indicating overall instability.

[0061] Figure 5 This is the plume change of a laser drilling method provided by the present invention within one scanning cycle (within 0.6s). Figure 4 , a strong plume appeared at 0.05s and remained stable as a whole.

[0062] Figure 6 This diagram illustrates the consistency of the shielding gas and the processing position. In the laser drilling method provided by the present invention, the laser processing area remains constant, so the shielding gas only needs to be blown toward the laser processing area. The rotation of the workpiece ensures that the shielding gas is blown in the same direction at all positions in the hole during drilling.

[0063] Figure 7 This is the effect of different scanning speeds (v, mm / s) and focus increment combinations on drilling time under a laser drilling process provided by the present invention. The figure only shows the parameters of successful drilling, and unsuccessful ones are not marked in the figure. Figure 7 The provided drilling duration can determine the optimal parameter combination for different processes. For conventional drilling methods, the optimal parameter combination is a scanning speed of 1000 mm / s and a focus increment of 0.075 mm. The optimal parameter combination for the laser drilling method provided by the present invention is a scanning speed of 2000 mm / s and a focus increment of 0.175 mm. This also verifies that the laser drilling method provided by the present invention can significantly improve the focus increment after optimizing the spatiotemporal distribution of laser energy.

[0064] Figure 8 The drilling process of the laser drilling method provided by the present invention is photographed and measured using a high-speed camera to record the time.

[0065] Figure 9 The geometrical morphology of the hole inlet and outlet obtained by conventional drilling method is poor in roundness, and both the inlet and outlet are elliptical and elongated along the direction of airflow.

[0066] Figure 10 The present invention provides a drilling method that significantly improves the roundness of the hole.

[0067] Figure 11 The hole wall quality obtained by conventional drilling methods is shown in Figure 1, where a1-a4 are high-magnification SEM scans and energy spectrum analysis tables of four characteristic areas of the hole wall. The hole wall obtained by conventional drilling methods has obvious defects such as ripples, residues, and microcracks.

[0068] Figure 12 This drilling method provides a method for achieving hole wall quality. Figures a1-a4 represent high-magnification SEM scans and energy spectrum analysis tables of four characteristic regions of the hole wall. The hole wall is smoother, fiber outlines are clearly visible, residue is significantly reduced, and ripples are suppressed.

[0069] Figure 13 This is the internal shape of the hole produced by the conventional drilling method. The hole has a large taper.

[0070] Figure 14 This is the internal morphology of a hole made by a laser drilling method provided by the present invention. The taper of the hole is significantly reduced.

[0071] Figure 15 The invention provides a laser hole making method for application in micro-holes with different tapers, different angles and different scales. Example 1

[0072] like Figure 1 As shown, a laser drilling method includes the following steps:

[0073] S1: Workpiece positioning and determination of target aperture;

[0074] like Figure 2 As shown, a laser beam layered drilling method is adopted. The drilling process is a double-circular rotation motion of the laser and the workpiece. That is, the laser beam is rotated by a galvanometer, and the workpiece is simultaneously rotated around its center, so that the rotation of the laser beam focus and the rotation of the workpiece are carried out simultaneously in the same direction or opposite directions. The rotation trajectory of the laser beam focus is a closed figure. The ratio of the rotation angular velocity of the workpiece to the rotation angular velocity of the laser beam focus is an irrational number, which makes the scanning motion trajectory of the laser beam focus in each layer change randomly, thereby removing the ripples on the hole wall and improving the smoothness of the hole morphology.

[0075] S2: Determine the workpiece rotation speed and the direction of the protective gas flow;

[0076] The direction of the protective airflow is always from the unprocessed area to the processed area, and it is tilted to the laser processing position;

[0077] S3: Determine laser power, laser frequency, scanning speed, laser beam focus movement diameter, and zoom increment;

[0078] Laser power: within the power range given by the equipment, the maximum laser power is preferred;

[0079] Laser frequency: the laser frequency corresponding to the maximum power;

[0080] Laser scanning speed: The specific value of the laser beam focus scanning speed v is determined based on the drilling time and drilling quality. The scanning speed corresponding to a short drilling time and good drilling quality is selected. The drilling quality is determined by the roundness and surface morphology of the hole.

[0081] Laser beam focus movement diameter: The laser beam focus rotation movement diameter d1 can be smaller than the target aperture. To ensure processing efficiency, a smaller size is preferred;

[0082] Zoom increment: Provides different focus increments to compare laser drilling times at different focus increments. Select the scanning speed that results in the shortest drilling time and the best drilling quality, as determined by hole roundness and surface topography.

[0083] During the entire drilling process, the center distance between the laser beam focus rotation axis and the workpiece rotation axis remains unchanged; the relative positions of the workpiece center rotation axis and the laser beam focus trajectory rotation axis in space remain unchanged;

[0084] S4: Determine the laser incident angle;

[0085] The laser incident angle is adjustable, using a three-dimensional galvanometer to adjust the laser incident angle by changing the laser beam focal position;

[0086] S5: Drilling using the processing parameters determined above

[0087] When drilling starts, the rotation axis of the workpiece coincides with the rotation axis of the laser beam focus.

[0088] Preferably, the trajectories of both the rotation of the laser beam focus and the rotation of the workpiece are circles.

[0089] As a preferred embodiment, the relative positions of the central rotation axis of the workpiece and the rotation axis of the laser beam focal track in space remain unchanged, which means that the distance between the two remains unchanged and the directions are constant.

[0090] As a preferred method, the rotation of the laser beam and the rotation of the workpiece are in opposite directions, because the reverse effect is better, there is a relative speed difference, the relative speed difference is larger, and the energy distribution is more uniform.

[0091] As a preferred method, when determining parameters, the drilling position can be adjusted without affecting the hole diameter and hole taper, for example, by using a slide module.

[0092] As a preferred method, the duration of laser drilling refers to the time from the start to the end of drilling, and the duration is calculated using laser processing software or a method of photographing.

[0093] As a preferred method, the spatial and temporal distribution control of laser energy and energy distribution control are achieved through the rotation of the workpiece and the rotational movement of the laser beam focus. After achieving energy distribution control, the focus increment is further improved. After matching the focus increment in step S3, the drilling efficiency is improved.

[0094] In a laser drilling method proposed by the present invention, the energy distribution of the laser beam focus in the processing area is determined by the motion trajectory. Figure 3 As shown, its motion trajectory is analyzed as follows: the laser focused spot makes a circular motion with a radius of r (mm) in the counterclockwise direction and a motion speed of v (mm / s). The workpiece makes a rotational motion in the clockwise direction with a rotation speed of ω (revolutions / minute). The distance between the workpiece spin center and the center of the circular motion of the spot is φ (mm). The laser is a pulsed laser with a pulse frequency of f (kHz). During the laser drilling process, the combined motion of the laser focused spot and the workpiece causes the spot to form a specific trajectory on the workpiece surface. In order to describe this trajectory, a fixed reference coordinate system is set with the workpiece spin center Q as the origin of the coordinate system. The position of the laser focused spot in the fixed coordinate system is:

[0095]

[0096] in: ,“ " is the angular velocity of the laser spot motion trajectory, "t" is the processing time, " is the distance between the laser focus spot and the origin of the coordinate system on the x-axis," " is the distance between the laser focus spot and the origin of the coordinate system on the y-axis. The rotation angle of the workpiece for:

[0097]

[0098] in: , " " is the angular velocity of the workpiece rotation, and "-" indicates clockwise rotation. Therefore, the motion trajectory equation of the laser beam focus in the processing area is:

[0099]

[0100] in:" " is the distance between the laser beam focus and the origin of the coordinate system on the x-axis," ” is the distance between the laser beam focus and the origin of the coordinate system on the y-axis.

[0101] The laser is pulsed, with a pulse frequency of f (kHz), emitting a pulse every ∆t = 1 / 1000f seconds. The laser processing process is performed at this interval. Based on the trajectory equation, it can be concluded that the energy distribution can be controlled by adjusting the processing parameters.

[0102] As a preferred embodiment, in S3, the selection of the laser beam focus rotational motion diameter d1 also depends on the material thickness. When the material thickness is ≤3 mm, the diameter d1 / material thickness = 10 / 1; when the material thickness is ≥3 mm, the diameter d1 / material thickness = 5 / 1.

[0103] As a preferred method, in step S4 of the present invention, the laser incident angle is achieved by adjusting the processing position. In a two-dimensional galvanometer or other types of laser equipment, the laser incident angle can also be adjusted by adjusting the posture of the workpiece or the posture of the laser beam.

[0104] As a preferred embodiment, in step S3 of the present invention, the focus increment is the distance the laser focus descends. When the laser focus position cannot be changed, the focus increment is the distance the workpiece ascends.

[0105] The laser drilling method provided by the present invention can freely adjust the laser incident focus in step S4, which is impossible to achieve with conventional laser drilling methods.

[0106] In step S2, the laser can be replaced with various types of lasers, including lasers of different wavelengths and lasers of different pulse widths;

[0107] In step S4 of the present invention, the laser incident angle is achieved by adjusting the processing position. In a two-dimensional galvanometer or other types of laser equipment, the laser incident angle can also be adjusted by adjusting the posture of the workpiece or the posture of the laser beam.

[0108] In step S3 of the present invention, the focus increment is the distance the laser focus descends. If the laser focus position cannot be changed, the focus increment can also be the distance the workpiece ascends. Example 2

[0109] The difference between this embodiment and embodiment 1 is that:

[0110] S1: Workpiece positioning and determination of target aperture; this implementation demonstrates the drilling effect of a target aperture of 0.5 mm.

[0111] S2: Determine the workpiece rotation speed and the direction of the protective gas flow; the workpiece rotation speed is 100 rpm.

[0112] S3: Determine the laser power, frequency, scanning speed, laser motion radius, and zoom increment; the laser power, frequency, and laser motion radius are 15W, 50kHz, and 0.15mm, respectively. To determine the optimal scanning speed and focus increment, multiple parameter combinations were set based on device performance and tested, as shown in the table below.

[0113] parameter Symbols and units Numerical Scan speed v, mm / s 100,300,500,1000,1500,2000,2500,3000,3500,4000,4500,5000 Zoom increment d2, mm 0.025, 0.05, 0.075, 0.1, 0.125, 0.15, 0.175, 0.2, 0.225

[0114] Because laser drilling efficiency is significantly affected by focus position, a reasonable focus increment ensures that the laser beam remains focused during the drilling process. Therefore, by comparing drilling times, the optimal scanning speed and corresponding focus increment can be determined for the two processes.

[0115] Figure 7 It shows that the focus increment has a decisive influence on the drilling efficiency. The optimal parameters of the laser drilling process provided by the present invention are v=2000 mm / s, d2=0.175mm, and the single hole takes only 18.38 s. Figure 8 The laser drilling method provided by the present invention demonstrates a drilling process, which reduces the fastest drilling time by 58.7% compared with conventional drilling processes.

[0116] S4: Determine the laser incident angle;

[0117] The laser incident angle parameters used in this article were obtained from previous laser cutting experiments. For details, see the reference [Anefficient high-quality cutting method for thick SiCf / SiC ceramic matrix composites using UV laser multiline layered scanning with focus increment optimization, Journal of Materials Processing Technology, Volume 335, January 2025, 118674]. This reference is used in this article. In practice, the specific laser incident angle can be set based on the hole shape requirements and the experimental results of various experiments.

[0118] S5: Drilling using the above-determined processing parameters;

[0119] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A laser drilling method, characterized in that The steps include: S1: Workpiece positioning and determination of target aperture; The laser beam layered drilling method uses a double-circular rotational motion of the laser and the workpiece. This involves rotating the laser beam through a galvanometer, while simultaneously causing the workpiece to rotate about its center. This allows the laser beam focus and the workpiece to rotate simultaneously in the same or opposite directions. The laser beam focus's rotational trajectory forms a closed graph, and the ratio of the workpiece's rotational angular velocity to the laser beam focus's rotational angular velocity is an irrational number. This causes the laser beam focus's scanning trajectory to change randomly across each layer, thereby removing ripples from the hole wall and improving the hole's smoothness. S2: Determine the workpiece rotation speed and the direction of the protective gas flow; The direction of the protective airflow is always from the unprocessed area to the processed area, and it is tilted to the laser processing position; S3: Determine laser power, laser frequency, scanning speed, laser beam focus movement diameter, and zoom increment; Laser power: Select the maximum laser power within the power range given by the equipment; Laser frequency: the laser frequency corresponding to the maximum power; Laser scanning speed: The specific value of the laser beam focus scanning speed v is determined based on the drilling time and drilling quality. The scanning speed corresponding to a short drilling time and good drilling quality is selected. The drilling quality is determined by the roundness and surface morphology of the hole. Laser beam focus movement diameter: The laser beam focus rotation movement diameter d1 can be smaller than the target aperture. To ensure processing efficiency, a smaller size is preferred; Zoom increment: Provides different focus increments to compare laser drilling times at different focus increments. Select the scanning speed that results in the shortest drilling time and the best drilling quality, as determined by hole roundness and surface topography. During the entire drilling process, the center distance between the laser beam focus rotation axis and the workpiece rotation axis remains unchanged; the relative positions of the workpiece center rotation axis and the laser beam focus trajectory rotation axis in space remain unchanged, that is, the distance between the two remains unchanged and the direction is constant; S4: Determine the laser incident angle; The laser incident angle is adjustable, using a three-dimensional galvanometer to adjust the laser incident angle by changing the laser beam focal position; S5: Drilling using the above-determined processing parameters; When drilling starts, the rotation axis of the workpiece coincides with the rotation axis of the laser beam focus.

2. A laser drilling method according to claim 1, characterized in that: The trajectories of both the rotation of the laser beam focus and the rotation of the workpiece are circles.

3. The laser drilling method according to claim 1, wherein: The rotation of the laser beam and the rotation of the workpiece are opposite to each other.

4. The laser drilling method according to claim 1, wherein: When determining parameters: the drilling position can be adjusted without affecting the hole diameter and hole taper.

5. The laser drilling method according to claim 1, wherein: The duration of laser drilling refers to the time from the start to the end of drilling. The laser drilling duration can be calculated using laser processing software or by photographing.

6. The laser drilling method according to claim 1, characterized in that: Through the rotation of the workpiece and the rotational motion of the laser beam focus, the spatial and temporal distribution control of the laser energy and the energy distribution control are achieved. After the energy distribution control is achieved, the focus increment is further improved. After the focus increment is matched in step S3, the drilling efficiency is improved.

7. The laser drilling method according to claim 1, characterized in that: In S3, the selection of the laser beam focus rotation movement diameter d1 also depends on the material thickness. When the material thickness is ≤3 mm, the diameter d1 / material thickness = 10 / 1; when the material thickness is ≥3 mm, the diameter d1 / material thickness = 5 / 1.

8. The laser drilling method according to claim 1, characterized in that: In step S4, the laser incident angle is achieved by adjusting the processing position. In a two-dimensional galvanometer or other types of laser equipment, the laser incident angle is adjusted by adjusting the posture of the workpiece or the posture of the laser beam.

9. The laser drilling method according to claim 1, wherein: In step S3 of the present invention, the focus increment is the distance the laser focus descends. If the laser focus position cannot be changed, the focus increment is the distance the workpiece rises.

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