A method for ultra-fast laser processing of rectangular inclined holes

Abstract

The present invention provides a method for ultra-fast laser machining of rectangular inclined holes. Based on the research idea of "line-surface-solid" progressive layer by layer, first, an ultra-fast laser grooving test is carried out to determine parameters such as the spot overlap rate and laser power; secondly, a line overlap rate test is carried out to select a suitable line overlap rate according to relevant evaluation criteria; thirdly, a surface scanning test is carried out to obtain the mapping relationship of ablation depth-related parameters according to the processing effect, and at the same time, a suitable surface scanning trajectory is selected and a suitable feed rate is selected as the focal point downward movement distance; finally, a through-hole test is carried out, and the test processing parameters are preferably selected according to the actual processing requirements by weight, and finally the machining of rectangular inclined holes is realized. The present invention systematically establishes a method for determining the processing parameters of ultra-fast laser machining of rectangular inclined holes, realizes high-quality and high-efficiency machining of rectangular holes with different inclination angles, and at the same time has a high degree of engineering application and low production cost.

Description

Technical Field

[0001] The present invention relates to the field of laser drilling of cooling holes on hot-end components of aero-engines, and in particular to a method for ultrafast laser machining of rectangular inclined holes. Background Art

[0002] Hot-end components in aero-engines, such as turbine blades, usually operate in an ultra-high temperature environment. The inlet temperature at the front end has reached as high as about 3800°F (2093°C), which has exceeded the service temperature of existing materials. Therefore, a large number of gas film cooling holes with various shapes need to be designed on the components for cooling. The diameter of the gas film cooling holes is between 300μm and 1000μm, and the shapes include straight round holes, inclined round holes, inclined rectangular holes, dustpan holes, etc., which pose challenges to the processing technology.

[0003] For the machining of gas film holes in high-temperature materials such as superalloys and single-crystal nickel-based superalloys, the commonly used machining methods at home and abroad are electrical discharge machining (EDM) and laser machining (LAM) (such as Chinese patent documents CN114289808A, CN112894040A, CN106735943B, CN113210856A). Although these patents have improved the machining quality and efficiency of gas film holes, when machining non-metallic materials or materials with poor conductivity such as ceramics and ceramic matrix composites, the electrical discharge machining method has certain limitations. For example, when the material of the hot-end component is a ceramic matrix composite, its conductivity is poor and there is a thermal barrier coating (TBC) on the surface (non-conductive), so the electrical machining process cannot be applied; currently, the shape of the gas film holes on the blades is also developing towards complex special shapes. Due to the single shape of the EDM electrode, it is impossible to machine special-shaped gas film holes with more excellent performance. For long-pulse laser machining, there are still disadvantages such as poor machining quality (processing defects such as recast layer, heat-affected zone, and cracks).

[0004] Therefore, there is an urgent need for an innovative machining method that takes into account both machining efficiency and hole shape quality. Compared with long-pulse machining, ultrafast laser machining has the advantages of a small heat-affected zone, almost no recast layer and thermal cracks, etc., and is a very promising machining technology for high-quality and high-efficiency machining of complex special-shaped gas film holes, such as (Chinese patent documents CN105458530B, CN113059277A, CN110202277B). These patents have all proposed methods for ultrafast laser machining of gas film holes. However, the current research direction of ultrafast laser machining of gas film holes mainly focuses on the research of round holes, and there is almost no research on inclined rectangular holes. The machining method depends entirely on the experience of workers, and there is no systematic research on the mapping model of multiple machining parameters on the machining results and the machining process that meets the machining requirements.

[0005] At present, there is no research method for ultra-fast laser processing of rectangular inclined holes. There is an urgent need to propose a research method for rectangular inclined holes to systematically study the determination and coupling regulation of multiple parameters, providing technical guidance for the ultra-fast laser processing of rectangular inclined holes. Summary of the Invention

[0006] To address the above-mentioned processing drawbacks and research gaps, the present invention provides a method for ultra-fast laser processing of rectangular inclined holes to solve the problems existing in the prior art. Based on the progressive research idea of "line-surface-solid", the present invention systematically establishes a method for determining the processing parameters of ultra-fast laser processing of rectangular inclined holes, realizes the processing of rectangular holes with different inclinations, and takes into account high-quality and high-efficiency processing. The technical means adopted by the present invention are as follows:

[0007] Based on the progressive research idea of "line-surface-solid", the present invention first conducts ultra-fast laser grooving tests to determine parameters such as spot overlap rate and laser power; secondly, conducts line overlap rate tests to select a suitable line overlap rate according to relevant evaluation criteria; thirdly, conducts surface scanning tests to obtain the mapping relationship of ablation depth-related parameters according to the processing effect, and at the same time selects a suitable surface scanning trajectory and selects a suitable feed rate as the focal point downward movement distance; finally, conducts through-hole tests to preferentially select test processing parameters according to the actual processing requirements by weight, and finally realizes the processing of rectangular inclined holes. Specifically,

[0008] A method for ultra-fast laser processing of rectangular inclined holes, comprising the following steps:

[0009] Step 1: Use a fixture to install the workpiece to be processed on the workbench, adjust the required angle θ between the workpiece and the workbench surface, fix and clamp it; adjust the relative position of the laser beam emitted by the laser and the workpiece, and use a CCD camera to locate the spot imaging position;

[0010] Step 2: Conduct single-line grooving tests in the X-axis and Y-axis directions. The X-axis direction is parallel to the workbench plane, the Y-axis direction is parallel to the workpiece plane, and the included angle with the workbench surface is θ. Through single-factor tests of different pulse energies E and spot overlap rates, obtain the variation law of the ablation profile with ultra-fast laser processing parameters. According to the ablation surface quality and line residue rate η as the evaluation criteria, determine the laser processing parameters including pulse energy E, spot overlap rate R s , spot overlap rate R P in the Y direction, ablation widths D X and D Y in the X and Y directions, and the optimal scanning speeds V X and V Y ;

[0011] Step 3: Conduct different line overlap rates λ dConduct experiments to observe the influence law of different laser parameters on the ablation junction profile. Select the appropriate line overlap rate λ by taking the processing efficiency and the multi-line residue rate β as the evaluation criteria. d And the line displacement amounts ΔX and ΔY in the X and Y directions;

[0012] Step Four: Use the single-line grooving experiment in Step Two and the line overlap rate λ d The processing parameters selected in the experiment to conduct surface scanning experiments with different types of scanning trajectories, and determine the appropriate single-layer scanning trajectory according to the processing quality and processing efficiency;

[0013] Step Five: Conduct a fixed-focus surface scanning experiment N times to determine the variation law of the processing depth H with the scanning times N, and determine the appropriate fixed-focus scanning times N c And the feed amount ΔZ;

[0014] Step Six: Conduct a through-hole experiment according to the parameters selected in the above steps. According to the relevant evaluation indexes of the through-hole quality and the hole wall taper, return to Step Two, Step Three, and Step Five to adjust the parameters until a through-hole that meets the requirements is machined, and determine the feed times S under different parameters;

[0015] Step Seven: Complete the machining, unload the workpiece from the workbench, and clean the workpiece.

[0016] Furthermore, the laser includes an ultrafast pulsed laser, specifically including picosecond laser and femtosecond laser, and its pulse width range is 5 fs - 10 ps.

[0017] Furthermore, in Step Two, the spot overlap rate in the X direction is obtained by the following formula:

[0018] R s =(D b -V X / f) / D b ;

[0019] The spot overlap rate in the Y direction is obtained by the following formula:

[0020] R P =(D a -V Y / f) / D a

[0021] In the formula, the major axis diameter of the spot projection is D a =2ω0 / cosθ, the minor axis diameter is D b =2ω0, ω0 is the beam waist radius, and f represents the laser frequency.

[0022] Furthermore, in Step Three, the line displacement amount in the X direction is obtained by the following formula:

[0023] ΔX = λd ×D b ;

[0024] The linear displacement in the Y direction is obtained by the following formula:

[0025] ΔY = λ d ×D a ;

[0026] Where: λ d represents the line overlap rate, the major axis diameter of the spot projection is D a = 2ω0 / cosθ, the minor axis diameter is D b = 2ω0, and ω0 is the waist radius.

[0027] Furthermore, the line overlap rate standard is 30% - 80%.

[0028] Furthermore, in the fourth step, the calculation formula for the required number of straight line scans P is:

[0029] P = (L - D X ) / ΔY + 1,

[0030] The time T to complete one surface scan is:

[0031] T = (W / V X ) × P + (P - 1) × (ΔY / V Y ),

[0032] Where, L is the length of the processed rectangular surface, and W is the width of the processed rectangular surface.

[0033] Furthermore, in the fifth step, for the selected Z-axis feed amount ΔZ, its evaluation index is mainly based on the processing efficiency and the processing depth H tending to be stable as the selection standard, and is affected by the line overlap rate and the ablation depth. The feed amount ΔZ should satisfy ΔZ = H ac , H ac is the depth at which the processing depth H gradually tends to be stable as the number of fixed-focus scans N increases.

[0034] Furthermore, the calculation formula for the number of feed times S is:

[0035] S = d / (cosθ × ΔZ).

[0036] Furthermore, the range of the inclination angle θ is 0° to 90°, which satisfies the processing of any inclined rectangular holes on the hot-end component. When it is 0°, it is a planar rectangular hole, and the laser beam is vertically irradiated on the workpiece surface.

[0037] Furthermore, the difficult-to-machine materials include high-performance alloys, nickel-based superalloys, single-crystal nickel-based, ceramic materials, particle-reinforced metal matrix composites, and fiber-reinforced ceramic matrix composites.

[0038] The present invention has the following advantages:

[0039] 1. This method provides a novel research method for processing inclined rectangular holes. The research process uses the "point-line-surface" progressive approach to systematically establish a method for determining the processing parameters of ultrafast laser processing rectangular inclined holes, realizing the processing of rectangular holes with different inclination angles, filling the gap in the processing of complex special-shaped holes in China. It solves the shortcomings of processing compared to traditional methods, and on this basis, takes into account high-quality and efficient processing at the same time, reducing production costs.

[0040] 2. This method realizes the coupling of test parameters at each stage of laser processing, and further provides a data model for each step of the test. In actual processing, the required data can be quickly found by referring to the relevant model, which solves the problem of traditional processing based on "experience", reduces trial processing time, reduces production costs, and greatly improves the industrial production of products.

[0041] 3. This method is based on the principle of ultrafast laser ablation, so this method is universal and can also be applied to the study of other complex special-shaped holes. This method is simple and convenient to operate, and it can achieve the most efficient processing while meeting the processing quality, providing an effective solution for the composite processing of difficult-to-process materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0043] Figure 1 A flow chart of a method for ultrafast laser processing of rectangular inclined holes is provided in the implementation of the present invention;

[0044] Figure 2 A schematic diagram of an ultrafast laser processing platform in the implementation of the present invention;

[0045] Figure 3 It is a schematic diagram of the laser spot projection at an angle θ with the horizontal plane in the implementation of the present invention;

[0046] Figure 4 Schematic diagram of the X and Y direction grooving test in the implementation of the present invention;

[0047] Figure 5 Schematic diagram of the grooving test with different spot overlap ratios in the X and Y directions in the implementation of the present invention;

[0048] Figure 6Schematic diagram of the influence law of the ablation knot profile in the line scanning test in the implementation of the present invention;

[0049] (a) Diagram of the variation relationship between different pulse energies E and ablation width D

[0050] (b) Diagram of the variation relationship between different pulse energies E and ablation depth H

[0051] (c) Different spot overlap rates R s Diagram of the variation law with the line residue rate η

[0052] Figure 7 For the line overlap rate λ in the implementation of the present invention d Test schematic diagram.

[0053] (a) Schematic diagram of the area with different line overlap rates λ d Diagram of the area

[0054] (b) Side view sectional drawing of the line overlap rate test

[0055] (c) Schematic diagram of the variation relationship between different line overlap rates and the multi-line residue rate β

[0056] Figure 8 Schematic diagram of the surface scanning test in the implementation of the present invention:

[0057] Figure 9 Schematic diagram of the machining depth of the surface scanning test in the implementation of the present invention

[0058] (a) Schematic diagram of the fixed-focus scanning times N and the machining depth H ac Schematic diagram

[0059] (b) Diagram of the variation law of the fixed-focus scanning times N and the machining depth H

[0060] Figure 10 Schematic diagram of the through-hole machining experiment in the implementation of the present invention

[0061] Figure 11 Schematic diagram of different trajectories of the surface scanning test in the implementation of the present invention:

[0062] In the figure: 1. Ultrafast laser, 2. Galvanometer system, 3. CCD camera, 4. Dichroic mirror, 5. Laser transmission unit, 6. Workpiece, 7. Workbench, 8. Multi-axis controller, 9. Control system, 601. Spot projection of the X-axis grooving test, 602. Spot projection of the Y-axis grooving test, 603. Laser trajectory of the surface scanning test. Specific implementation mode

[0063] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] As Figure 2 shown, the present invention is implemented based on the following device. The processing platform includes an ultrafast laser 1, a galvanometer system 2, a CCD camera 3, a dichroic mirror 4, a laser transmission unit 5, a multi-axis controller 8, a control system 9, a workpiece 6, a workbench 7, a multi-axis controller 8, a control system 9, etc. The control system is connected to the workbench through the multi-axis controller. The workpiece is arranged on the workbench. The control system is connected to the ultrafast laser. The ultrafast laser passes through the galvanometer system and is reflected by the dichroic mirror onto the laser transmission unit. The CCD camera takes pictures of the state of the workpiece below it through the dichroic mirror. The ultrafast laser, the galvanometer module and the multi-axis controller are all controlled by the control system, and the positioning accuracy can reach up to 5 μm at most, meeting the processing requirements of rectangular holes.

[0065] As Figure 1 shown, a flowchart of a method for processing rectangular inclined holes with an ultrafast laser. This processing method flow includes the following steps:

[0066] Step 1: Use a fixture to install the workpiece 101 to be processed on the workbench 102, adjust the angle θ between the workpiece and the workbench surface to the required angle, fix and clamp it; adjust the relative position between the laser beam emitted by the laser and the workpiece, and use the CCD camera 3 to locate the imaging position of the light spot.

[0067] Step 2: Turn on the laser 1, the control system 9, control the multi-axis controller 8, and the galvanometer module 2, and perform single-line grooving tests in the X-axis and Y-axis directions. The X-axis direction is parallel to the workbench plane, and the Y-axis direction is parallel to the workpiece plane and forms an angle θ with the workbench surface. Through single-factor tests of different pulse energies E and spot overlap ratios, obtain the variation law of the ablation profile with ultrafast laser processing parameters, and determine the appropriate pulse energy E, the spot overlap ratio R in the X direction s , the spot overlap ratio R in the Y direction P , the optimal V X and V Y scanning speeds and other laser processing parameters such as;

[0068] Step 3: Perform different line overlap ratios λ dConduct experiments to observe the influence law of different laser parameters on the ablation junction profile, and select an appropriate line overlap rate λ based on relevant evaluation indicators such as processing efficiency and multi-line residue rate β. d ;

[0069] Step 4: Use the processing parameters selected in the single-line grooving experiment in Step 2 and the line overlap rate λ d from the experiment in Step 3 to conduct surface scanning experiments with different types of scanning trajectories, and determine an appropriate single-layer scanning trajectory based on processing quality and processing efficiency;

[0070] Step 5: Conduct a fixed-focus N-time surface scanning experiment to determine the variation law of the processing depth H with the scanning times N, and determine an appropriate fixed-focus scanning times N c and feed rate ΔZ.

[0071] Step 6: Conduct a through-hole experiment according to the parameters selected in the above steps. According to relevant evaluation indicators such as through-hole quality and hole wall taper, return to Step 2, Step 3, and Step 5 to appropriately adjust the parameters until a through-hole meeting the requirements is machined, and determine the feed times S under different parameters; Three levels (Ⅰ, Ⅱ, Ⅲ) of reference indicators are designed in Step 6, where the Ⅰ level is the most priority consideration factor, the Ⅱ level is the secondary consideration factor, and the Ⅲ level is the last consideration factor.

[0072] Step 7: Turn off the ultrafast laser 1 and the control system 9, complete the processing, remove the workpiece 6 from the workbench 7, and clean the workpiece.

[0073] As Figure 3 shown is a schematic diagram of the laser spot projected at an angle θ with the horizontal plane. Due to the angle θ between the workpiece and the workbench, the laser spot that is circular in the horizontal plane is approximately an elliptical spot when projected onto the workpiece.

[0074] As Figure 4 shown is a schematic diagram of the grooving experiment in the X and Y directions. In the Cartesian coordinate system, Figure (a) shows that the laser spot scanning speed V X moves along the X direction and the overlapping area of the laser spot projection 601 in the X-direction grooving experiment overlaps with the short axis part of the ellipse. Figure (b) shows that the laser spot scanning speed V Y moves along the Y direction, the Y direction is parallel to the workpiece and forms an angle θ with the workbench. The overlapping area of the laser spot projection 602 in the Y-direction grooving experiment overlaps with the long axis part of the ellipse.

[0075] As Figure 5 shown is a schematic diagram of different spot overlap rates in the X and Y direction grooving experiments. D X , D Y are respectively the ablation channel widths scanned in the X and Y directions. Figure (a) shows different spot overlap rates R S (R sl >R sm >Rsh ) Schematic diagram, and Figure (b) shows different light spot overlap ratios R when the moving direction is Y P (R sl >R sm >R sh ) Schematic diagram. Where R S =(D b -V X / f) / D b )、R P =(D a -V Y / f) / D a ).

[0076] As Figure 6 shown in the schematic diagram of the influence law of the ablation knot profile in the line scanning test, in the line scanning test, the change trends of the parameters in Figures (a), (b), and (c) should be combined. The ablation width D (D h >D m >D1) and the ablation depth H (H h >H m >H1) both increase with the increase of the pulse energy E. The line residue rate η decreases with the increase of the light spot overlap ratio R s . By observing the groove processing quality and processing efficiency through a 3D confocal microscope, select appropriate H h , low ablation depth H1 and high ablation depth H h between, and further optimize the appropriate pulse energy E, R m . m S d .

[0077] As Figure 7 (a) shows the schematic diagram of different line overlap ratios λ d (λ dh >λ dl ) test. When V X is the light spot scanning speed, the calculation formula for its line overlap ratio is λ d =(ΔY / D a )×100%, where ΔY = λ d ×D a . When V Y is the light spot scanning speed, the calculation is the same. The line overlap ratio mainly affects the processing efficiency. When observing the influence law of different parameters on the ablation structure in the test, select the appropriate line overlap ratio through the processing efficiency and multi-line residue rate related evaluation indicators. According to actual processing experience, when the line overlap ratio is between 30% - 80%, its quality and efficiency reach the optimal value; in the side view profile diagram (b) of the line overlap ratio test, h L is the ablation depth, h Lris the residual height. In Figure (c), the multi-line residual rate β (β dl > β dh ) decreases as the line overlap rate λ d (λ dh > λ dl ) increases. The calculation method of the line residual rate η in Step 2 is the same as that of the multi-line residual rate β. In actual processing, the optimal value is selected according to needs.

[0078] As shown in the schematic diagram of the surface scanning test Figure 8 as shown, the laser scans along the trajectory 603 to machine a rectangular surface with a length of L and a width of W. The spacing between each scan line is ΔY. The calculation formula for the number of scan lines P is P = (L - D X ) / ΔY + 1. The time T required to complete one surface scan is

[0079] T = (W / V X ) × P + (P - 1) × (ΔY / V Y ).

[0080] In this embodiment, the mentioned processing efficiency can be approximated as the processing time. The scanning time T can be regarded as a reference quantity for the processing efficiency. The shorter the time, the higher the processing efficiency.

[0081] As shown in Figure 9 the schematic diagram of the variation law of the processing depth in the surface scanning test (b), the processing depth H gradually stabilizes as the number of fixed-focus scans N increases. In actual processing, the stable H ac corresponding to Nc should be selected as the number of fixed-focus scans.

[0082] As shown in Figure 10 , where d is the workpiece thickness, ΔZ represents the feed amount of the light spot along the Z-axis after N fixed-focus scans, and it satisfies the relationship ΔZ = H ac . S represents the number of times the laser needs to feed along the Z-axis, and its expression is S = d /

[0083] (cosθ × ΔZ).

[0084] As shown in Figure 11 is the schematic diagram of different trajectories in the surface scanning test. The specific research method is the same as that of the present invention, only the trajectories are different. Specifically, the surface scanning trajectories in Step 6 include but are not limited to the trajectories shown in this patent, and also include various trajectories such as linear, S-shaped, #-shaped, square-shaped, and spiral-shaped.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for processing rectangular inclined holes by an ultrafast laser, characterized in that, It includes the following steps: Step 1: Use a fixture to install the workpiece to be processed on the workbench, adjust the required angle θ between the workpiece and the workbench surface, fix and clamp it; adjust the relative position between the laser beam emitted by the laser and the workpiece, and use a CCD camera to locate the imaging position of the light spot; Step 2: Conduct single-line grooving tests on the X-axis and Y-axis. The X-axis direction is parallel to the workbench plane, and the Y-axis direction is parallel to the workpiece plane and forms an angle θ with the workbench surface. By performing single-factor tests on different pulse energies E and spot overlap rates, the variation law of the ablation profile with ultrafast laser processing parameters is obtained. According to the ablation surface quality and line residue rate η as the evaluation criteria, determine the laser processing parameters including the pulse energy E, the spot overlap rate R s in the X direction, the spot overlap rate R P in the Y direction, the ablation widths D X and D Y , and the optimal scanning speeds V X and V Y in the X and Y directions; Step 3: Conduct experiments on different line overlap ratios λ d to observe the influence law of different laser parameters on the ablation junction profile, and select an appropriate line overlap ratio λ using the processing efficiency and multi-line residue ratio β as evaluation criteria d and the line displacement amounts ΔX and ΔY in the X and Y directions; Step 4: Use the single-line grooving test in Step 2 and the line overlap rate λ in Step 3 d Select the processing parameters for the test, conduct surface scanning tests with different types of scanning trajectories, and determine the appropriate single-layer scanning trajectory based on the processing quality and efficiency. Step 5: Conduct a fixed-focus N-surface scanning test to determine the variation law of the machining depth H with the scanning number N, and determine the appropriate fixed-focus scanning number N c and the feed rate ΔZ; Step 6: Conduct a through-hole experiment according to the parameters selected in the above steps. According to the relevant evaluation indexes of the through-hole quality and the hole wall taper, return to Step 2, Step 3, and Step 5 to adjust the parameters until a through-hole that meets the requirements is processed, and determine the feed times S under different parameters; Step 7: Complete the processing, unload the workpiece from the workbench, and clean the workpiece.

2. The method for ultra-fast laser processing of rectangular inclined holes according to claim 1, characterized in that, The laser includes an ultrafast pulsed laser, specifically including picosecond laser and femtosecond laser, and its pulse width range is 5 fs - 10 ps.

3. The method for ultrafast laser machining of rectangular inclined holes according to claim 1, characterized in that, In Step 2, the overlapping rate of the light spots in the X direction is obtained by the following formula: R s = (D b - V X / f) / D b ; The overlapping rate of the light spots in the Y direction is obtained by the following formula: R P = (D a - V Y / f) / D a In the formula, the major axis diameter of the spot projection is D a = 2ω0 / cosθ, and the minor axis diameter is D b = 2ω0, where ω0 is the waist radius and f represents the laser frequency.

4. The method for ultra-fast laser machining of rectangular inclined holes according to claim 3, characterized in that, In Step 3, the linear displacement in the X direction is obtained by the following formula: ΔX = λ d × D b ; The linear displacement in the Y direction is obtained by the following formula: ΔY = λ d × D a ; Where: λ d represents the line overlap rate, the major axis diameter of the spot projection is D a = 2ω0 / cosθ, the minor axis diameter is D b = 2ω0, where ω0 is the waist radius.

5. The method for ultrafast laser machining of rectangular inclined holes according to claim 4, wherein The standard of the line overlapping rate is 30% - 80%.

6. The method for ultra-fast laser machining of rectangular inclined holes according to claim 4, wherein In the said Step 4, the calculation formula for the required number of linear scans P is: P = (L - D X ) / ΔY + 1, The time T for completing one surface scan is: T = (W / V X ) × P + (P - 1) × (ΔY / V Y ) Where, L is the length of the processed rectangular surface, and W is the width of the processed rectangular surface.

7. The method for ultra-fast laser machining of rectangular inclined holes according to claim 6, characterized in that, In Step 5, for the selected Z-axis feed ΔZ, the evaluation index is based on the criterion that the machining efficiency and the machining depth H tend to be stable, and it is affected by the wire overlap rate and the ablation depth. The feed ΔZ should satisfy ΔZ = H ac , H ac is the depth at which the machining depth H gradually tends to be stable as the number of fixed-focus scans N increases.

8. The method for ultrafast laser machining of rectangular inclined holes according to claim 7, characterized in that, The calculation formula for the feed times S is: S = d / (cosθ × ΔZ).

9. The method for ultra-fast laser machining of rectangular inclined holes according to claim 1, characterized in that, The range of the inclination angle θ is 0° to 90°, which meets the processing of any inclined rectangular holes on the hot-end component. When it is 0°, it is a planar rectangular hole, and the laser beam is vertically irradiated on the workpiece surface.

10. The method for ultra-fast laser machining of rectangular inclined holes according to claim 1, characterized in that, The materials of the workpiece to be processed include high-performance alloys, nickel-based superalloys, single-crystal nickel-based, ceramic materials, particle-reinforced metal matrix composites, and fiber-reinforced ceramic matrix composites.

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