Laser compound processing method for inclined deep hole

Abstract

The present application belongs to the technical field of laser processing, and relates to a laser composite processing method for an inclined deep hole, comprising the following steps: a laser path scanning system controls a first short pulse laser beam to remove processing layer by layer from top to bottom along a hole axis until a flat area perpendicular to the hole axis is formed by removing an inclined part of a workpiece; a laser processing head emits a long pulse laser beam pulse train to process the flat area, forming a through hole with a minimum cross-sectional size smaller than that of a target hole; and the laser path scanning system controls a second short pulse laser beam to remove processing from top to bottom along the hole axis until a complete hole fully corresponding to the three-dimensional size of the target hole is processed. The method can realize the processing of an extreme inclined hole with an included angle β between the axis of the target hole and the normal of the hole surface being greater than 70°, and simultaneously adopts a three-step composite method of short pulse laser-long pulse laser-short pulse laser, giving consideration to processing quality and processing efficiency, and can realize the processing of equal-diameter holes and variable-diameter special-shaped holes.

Description

Technical Field

[0001] This invention belongs to the field of laser processing technology and relates to a laser composite processing method for tilted deep holes. Background Technology

[0002] In modern manufacturing, there are numerous challenges in machining deep, inclined holes, such as fuel injection holes in internal combustion engines, film cooling holes in aero-engine combustion chambers and guide vanes. These require machining densely packed, high-aspect-ratio, and highly inclined straight circular holes or arrays of irregularly shaped holes on the walls of components made of high-generation single crystals, thermally barrier coated high-temperature alloys, and ceramic matrix composites. With the development of laser technology, high-power, high-beam-quality short-pulse lasers and ultrafast lasers have emerged. Due to their extremely short duration and extremely high light intensity density, they can significantly reduce thermal and mechanical damage during material processing, greatly improving laser processing quality, and are widely used for precision micro-hole machining of various materials. However, limited by low single-pulse energy (0.1–2 mJ) and low average power (40–100 W), short-pulse lasers and ultrafast lasers still suffer from low efficiency when machining deep, inclined holes, making it difficult to meet the high-speed hole-making requirements of engineering applications.

[0003] With the rise of high-power fiber lasers, long-pulse laser drilling technology is increasingly used in high-speed drilling. By modulating continuous or quasi-continuous lasers into pulse widths in the millisecond and microsecond range, their average power reaches 500–15000W, and single-pulse energy can reach tens of joules, enabling high-speed material removal for drilling. However, in practical drilling applications, it has been found that when the angle β between the axis of the target hole (the straight line passing through the center of the hole and extending along its length) and the normal to the workpiece surface (the normal to the surface is a straight line perpendicular to the tangent at a point on the surface) increases to over 60°, the efficiency and quality of long-pulse laser drilling on inclined workpieces decrease significantly. In some cases, when the angle β between the axis of the target hole and the normal to the inclined workpiece surface increases to over 70°, it becomes impossible to drill through the hole. This is because as the curvature of the workpiece surface changes, the incident angle during laser processing also changes, thus altering the shape, size, and energy distribution of the laser spot projected onto the surface, thereby affecting the efficiency and quality of laser processing.

[0004] Furthermore, long-pulse laser processing exhibits significant thermal effects. During rapid cooling, molten material inevitably forms a remelted layer or even microcracks, making it difficult to meet the high surface integrity requirements for deep hole processing. Simultaneously, due to its lower processing resolution, long-pulse lasers are ill-suited for processing complex, irregularly shaped holes and other three-dimensional fine structures.

[0005] Chinese patent CN116100170A discloses a method for high-quality and high-efficiency processing of inclined holes using ultrafast lasers. It adopts a three-stage processing method, selecting different scanning modes and processing parameters in the inlet, middle and outlet stages to solve the problems of poor hole wall quality and poor process stability in inclined holes. However, due to the use of a single ultrafast laser processing method, it is still difficult to avoid the problem of low efficiency when processing inclined deep small holes. Chinese patent CN118385894A discloses a method for processing cooling holes in heavy-duty gas turbine blades with a double-ceramic layer thermal barrier coating. The method uses a long-pulse laser to process circular film cooling holes in the turbine blades, and an ultrafast laser to perform rotary cutting along the circular holes on the coating side of the turbine blades, cutting out scoop-shaped or trapezoidal holes that meet design requirements. The axial direction of the cooling holes is at an angle of 22-60° to the normal of the thermal barrier coating surface. Therefore, it avoids the situation where the efficiency and quality of long-pulse laser processing holes on inclined workpieces significantly decreases when the angle β between the axis of the target hole and the normal of the curved surface at the hole increases to more than 60°, or even when the angle β between the axis of the target hole and the normal of the curved surface at the hole increases to more than 70°, making it impossible to penetrate the hole.

[0006] The aforementioned problems severely limit the practical application of laser processing technology for tilted deep holes. Therefore, there is an urgent need for a high-quality and efficient laser processing method for tilted deep holes to improve the processing quality while significantly increasing processing efficiency. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, the present invention aims to provide a laser composite processing method for inclined deep holes, thereby overcoming the shortcomings of the prior art.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A laser composite processing method for inclined deep holes includes the following steps:

[0010] S1. The laser path scanning system controls a first short-pulse laser beam to remove the workpiece layer by layer from top to bottom along the hole axis until the inclined part of the workpiece is removed to form a flat area perpendicular to the hole axis. The size of the flat area is smaller than the minimum cross-sectional size of the target hole.

[0011] S2. The laser processing head emits a long pulse laser beam pulse train to process in a flat area, forming a through hole with a diameter smaller than the minimum cross-sectional size of the target hole;

[0012] S3. The laser path scanning system controls a second short-pulse laser beam to remove material along the hole axis from top to bottom until a complete hole that perfectly matches the three-dimensional dimensions of the target hole is produced.

[0013] Preferably, when the workpiece is a workpiece substrate and is not covered with a thermal barrier ceramic coating, step S1 includes the following sub-steps:

[0014] S101. Determine the model of the inclined part to be removed based on the angle α between the axis of the target hole and the tangent of the workpiece surface, as well as the size of the flat area.

[0015] S102. Slice the inclined part of the model into layers along the direction of the hole axis and extract the contour of each layer;

[0016] S103. Fill the area formed by the contour, plan the laser scanning path, and determine the laser beam scanning trajectory;

[0017] S104. Clamp the workpiece and tilt it to the machining position and machining angle;

[0018] S105. Set laser processing parameters;

[0019] S106. Turn on the coaxial water flow or coaxial air blowing;

[0020] S107. The laser path scanning system controls the first short pulse laser beam to perform removal processing according to the set scanning trajectory until the inclined part of the workpiece is removed to form a flat area perpendicular to the hole axis, and a point on the flat area is connected to a point on the workpiece processing surface.

[0021] Preferably, when the workpiece is a workpiece substrate with a surface covered by a thermal barrier ceramic coating, step S1 includes the following sub-steps:

[0022] S101. Determine the model of the inclined part to be removed based on the angle α between the axis of the target hole and the tangent of the workpiece surface, as well as the size of the flat area.

[0023] S102. Slice the inclined part of the model into layers along the direction of the hole axis and extract the contour of each layer;

[0024] S103. Fill the area formed by the contour, plan the laser scanning path, and determine the laser beam scanning trajectory;

[0025] S104. Clamp the workpiece and tilt it to the machining position and machining angle;

[0026] S105. Set laser processing parameters;

[0027] S106. Turn on the coaxial water flow or coaxial air blowing;

[0028] S107. The laser path scanning system controls the first short pulse laser beam to perform removal processing according to the set scanning trajectory. After removing the covering thermal barrier ceramic coating, the processing continues until the inclined part of the workpiece substrate is removed to form a flat area perpendicular to the hole axis. A point on the flat area is connected to a point on the processing surface of the workpiece substrate.

[0029] Preferably, the inclined portion model is centered on the axis of the hole, and the flat area formed is also centered on the axis of the hole.

[0030] Preferably, in step S103, the area formed by the contour is filled at certain intervals using any one of the following methods: cross, concentric circles, or spiral.

[0031] The shape of the flat area is arbitrary. It can correspond to the cross-sectional shape of the target hole. For example, if the cross-section of the hole is circular, then the flat area is circular. Alternatively, it can not correspond to the cross-sectional shape of the target hole and can exhibit any shape, as long as the size of the flat area is smaller than the minimum cross-sectional size of the target hole.

[0032] The minimum cross-sectional dimension of the target hole refers to the size of the smallest portion of the cross-sectional dimension of the target hole along the entire hole axis.

[0033] Preferably, step S2 includes the following sub-steps:

[0034] S201. Start coaxial air blowing;

[0035] S202. The long pulse laser beam emitted by the laser processing head performs processing in a flat area;

[0036] S203. The laser processing head moves in a plane perpendicular to the hole axis;

[0037] S204. As the hole is penetrated deeper, the laser processing head moves along the hole axis to compensate for the focal length until a through hole with a diameter smaller than the minimum cross-sectional size of the target hole is formed.

[0038] Preferably, step S3 includes the following sub-steps:

[0039] S301. Slice the overall model of the target hole into layers along the hole axis and extract the contour of each layer;

[0040] S302. Form a new shape by combining the outline with the cross-sections that have been removed in steps S1 and S2;

[0041] S303. Fill the area of ​​the new graphic, plan the laser scanning path, and determine the laser beam scanning trajectory;

[0042] S304. Set laser processing parameters;

[0043] S305. Turn on the coaxial water flow or coaxial air blowing;

[0044] S306. The laser path scanning system controls the second short-pulse laser beam to remove material along the hole axis from top to bottom until a complete hole that perfectly matches the three-dimensional dimensions of the target hole is produced.

[0045] Preferably, in step S303, the area of ​​the new graphic is filled at certain intervals using any one of the following methods: cross, concentric circles, or spiral.

[0046] Preferably, the laser path scanning system is one of a five-axis scanning galvanometer, a rotary cutting system, a two-axis scanning galvanometer, and a three-axis scanning galvanometer.

[0047] Preferably, the first and second short-pulse laser beams are emitted by a short-pulse laser, which is one of a nanosecond laser, a picosecond laser, or a femtosecond laser. Therefore, the first and second short-pulse laser beams can be one of a nanosecond laser beam, a picosecond laser beam, or a femtosecond laser beam, respectively. The first and second short-pulse laser beams can be emitted by the same short-pulse laser or by different short-pulse lasers.

[0048] Preferably, the pulse widths of the first and second short-pulse laser beams are 1 fs to 1000 ns. More preferably, they are 10 fs to 800 ns.

[0049] Further optimization is that the pulse width of the second short-pulse laser beam is smaller than that of the first short-pulse laser beam.

[0050] Further optimization reveals that the pulse width of the first short-pulse laser beam is 10–800 ns, and the pulse width of the second short-pulse laser beam is 10–800 fs.

[0051] The laser processing parameters for short-pulse lasers can be listed as follows: laser frequency of 1–500 kHz, pulse width of 1 fs–1000 ns, average laser power of 1–500 W, and laser scanning speed of 5–5000 mm / s. Further, the laser processing parameters for short-pulse lasers can be listed as follows: laser frequency of 5–200 kHz, pulse width of 10 fs–800 ns, average laser power of 10–300 W, and laser scanning speed of 20–2000 mm / s.

[0052] Preferably, the laser processing head is a continuous fiber laser or a quasi-continuous fiber laser.

[0053] Preferably, the pulse width of the long pulse laser beam pulse train emitted by the laser processing head is 1 to 100 ms, and the power is 1 to 1000 W.

[0054] The final machined hole can be a constant-diameter hole with a fixed cross-section or a non-standard hole with a varying cross-section. A constant-diameter hole means that the cross-sectional shape and size are exactly the same at any position along the entire hole axis.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) A water-assisted or gas-assisted short-pulse laser is used to remove the inclined portion of the workpiece substrate, forming a flat area perpendicular to the hole axis, providing conditions for subsequent efficient pre-drilling with a long-pulse laser; a gas-assisted long-pulse laser is used for efficient drilling, forming a through hole with a size smaller than the target hole cross-section, providing a channel for the effective removal of material particles and impurities generated in the next short-pulse laser processing; finally, a water-assisted or gas-assisted short-pulse laser is used to complete the processing of the entire hole. Combining the advantages of high processing efficiency of long-pulse laser and good processing quality of short-pulse laser, high-quality and high-efficiency inclined deep hole processing is achieved.

[0057] (2) The processing method of the present invention can realize the processing of ultra-large inclined holes with a depth-to-diameter ratio greater than 20 and an angle β between the hole axis and the surface normal of the workpiece greater than 60°, and can even realize the processing of extreme inclined holes with an angle β greater than 70°, breaking through the limitations of the prior art in the processing of large inclined holes.

[0058] (3) The processing method of the present invention can not only process conventional equal-diameter holes such as straight round holes and straight square holes, but also process irregular holes such as winnowing basket holes and cat ear irregular holes, thus meeting the processing requirements of complex irregular holes and other three-dimensional fine structures.

[0059] (4) In addition, the processing method of the present invention is also applicable to the drilling of high-temperature alloy plates and blades with thermal barrier coatings, which solves the problem of processing inclined deep holes on such special workpieces and expands the application scope of laser processing technology in aerospace, energy and other fields. Attached Figure Description

[0060] Figure 1 This is a flowchart of the laser composite processing method for inclined deep holes provided by the present invention;

[0061] Figure 2 This is a flowchart of the optimized laser composite machining method for tilted deep holes provided by the present invention;

[0062] Figure 3 This is a schematic diagram of the process of machining inclined equal-diameter holes on a workpiece substrate without thermal barrier ceramic coating according to the present invention.

[0063] Figure 4 This is a schematic diagram of the process of machining inclined equal-diameter holes on a workpiece substrate with a thermal barrier ceramic coating according to the present invention;

[0064] Figure 5 This is a schematic diagram of the slicing, contour extraction, and region filling in step S3 of the present invention.

[0065] Among them, 1-workpiece substrate, 2-thermal barrier ceramic coating, 3-curved surface normal of workpiece substrate, 4-axis of hole, 5-flat area, 6-through hole formed by long pulse laser processing, 7-through hole formed by final processing, 10-laser path scanning system, 11-first type of short pulse laser beam, 12-second type of short pulse laser beam, 20-laser processing head, 21-continuous fiber laser pulse train. Detailed Implementation

[0066] The technical solution of the present invention will be further described and illustrated below with reference to specific embodiments and accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of helping to understand the present invention and are not intended to limit the specific scope of the present invention. Furthermore, the accompanying drawings used herein are merely for better illustrating the content disclosed in the present invention and do not limit the scope of protection. Unless otherwise specified, the raw materials used in the embodiments of the present invention are all commonly used in the art, and the methods used in the embodiments are all conventional methods in the art.

[0067] Example 1

[0068] Example 1: An inclined rectangular hole is machined on a workpiece substrate (here, a high-temperature alloy plate) 1 with a thickness of 5 mm. The angle β between the hole axis 4 and the normal 3 of the workpiece surface is 75°. The diameter D3 (i.e., the side length of the rectangular hole) of the rectangular hole is 1.0 mm, the depth of the rectangular hole is approximately 19.3 mm, and the depth-to-diameter ratio is approximately 19.3:1. A schematic diagram of the hole fabrication is shown below. Figure 3 As shown, the specific steps include the following:

[0069] S101. Based on the angle α = 15° between the axis 4 of the target hole and the tangent of the workpiece surface and the removal range of 0.8mm (D1), the model of the inclined part to be removed is obtained. The inclined part model is centered on the hole axis and the height of the inclined part model is approximately H1 = 2.98mm.

[0070] S102. The inclined part of the model is horizontally sliced ​​and layered along the direction of the hole axis 4 with a thickness h1 = 0.2 mm, and divided into 15 layers. Each layer represents a cross-sectional profile of the model at that location. The profile of each layer is extracted.

[0071] S103. The area formed by the contour is filled with cross lines at intervals of d = 0.02 mm to plan the laser scanning path and determine the laser beam scanning trajectory;

[0072] S104. Clamp the workpiece and tilt it to the machining position and machining angle;

[0073] S105. Set the laser processing parameters: laser frequency f = 50kHz, pulse width 100ns, average laser power P = 50W, and laser scanning speed v = 800mm / s;

[0074] S106. Start coaxial air blowing until step S1 is completed;

[0075] S107. Select a laser path scanning system (in this case, a five-axis scanning galvanometer) 10 to control the first short-pulse laser beam (in this case, a nanosecond laser beam) 11 to perform removal processing according to the set scanning trajectory until the inclined part of the workpiece substrate is removed, forming a flat area 5 perpendicular to the hole axis 4. This flat area is approximately square, with the hole axis as the center. A point on one side of the square is connected to a point on the workpiece substrate processing surface. The dimension (i.e., side length) of this flat area is D1 = 0.8 mm. Figure 3 As shown in S1.

[0076] S201. Start coaxial air blowing until step S2 is completed;

[0077] S202. The laser processing head 20 emits a continuous fiber laser pulse train 21 to process a flat area. The average laser power is 500W and the pulse width is modulated to 20ms.

[0078] S203. The laser processing head also moves in a plane perpendicular to the hole axis;

[0079] S204. As the hole is deepened, the laser processing head 20 moves along the hole axis 4 to compensate for the focal length, ensuring that the laser energy is concentrated at the required position, until a through hole with a size D2 = Φ0.6mm is formed, such as... Figure 3 As shown in S2.

[0080] S301. The overall model of the rectangular hole is horizontally sliced ​​along the hole axis with a thickness of h2 = 0.1 mm, resulting in a total of 193 layers. The contour of each layer is extracted.

[0081] S302. Combine the described contour with the cross-sections from S1 and S2 that have already been removed to form a new shape, such as... Figure 5 As shown;

[0082] S303. Using concentric circles to fill the area of ​​the new graphic in S302 at intervals of d = 0.02 mm, the laser scanning path is planned to determine the laser beam scanning trajectory;

[0083] S304. Set the laser processing parameters: laser frequency f = 100kHz, pulse width 500fs, average laser power = 100W, laser scanning speed v = 1000mm / s;

[0084] S305. Start coaxial air blowing until step S3 is completed;

[0085] S306. Select a laser path scanning system (a five-axis scanning galvanometer) 10 to control a second short-pulse laser beam (a femtosecond laser beam) 12 to remove material along the hole axis from top to bottom until a complete rectangular hole with a size D3 = 1.0 mm is produced. Figure 3 As shown in S3.

[0086] Example 2

[0087] Example 2: An inclined straight circular hole is machined on a workpiece substrate (here, a high-temperature alloy plate) 1, the workpiece to be processed—a workpiece substrate 1 with a surface covered by a 0.5mm thick thermal barrier ceramic coating 2 and a thickness of 5mm. The angle β between the hole axis 4 and the workpiece surface normal 3 is 70°. The diameter of the straight circular hole, D3, is Φ0.8mm, and the depth of the straight circular hole is approximately 16.1mm, with a depth-to-diameter ratio of approximately 20:1. A schematic diagram of the hole preparation is shown below. Figure 4 As shown, the specific steps include the following:

[0088] S101. Based on the angle α = 20° between the axis 4 of the target hole and the tangent of the workpiece surface and the removal range of 0.6mm (D1), the model of the inclined part to be removed is obtained. The inclined part model is centered on the axis of the hole, and the height of the inclined part model is approximately H1 = 1.65mm.

[0089] S102. The inclined part of the model is horizontally sliced ​​and layered along the direction of the hole axis 4 with a thickness h1 = 0.05 mm, and divided into 33 layers. Each layer represents a cross-sectional profile of the model at that location. The profile of each layer is extracted.

[0090] S103. The area formed by the contour is filled with cross lines at intervals of d = 0.02 mm to plan the laser scanning path and determine the laser beam scanning trajectory;

[0091] S104. Clamp the workpiece and tilt it to the machining position and machining angle;

[0092] S105. Set the laser processing parameters: laser frequency f = 10kHz, pulse width 100ns, average laser power P = 10W, and laser scanning speed v = 200mm / s.

[0093] S106. Start the coaxial water jet until step S1 is completed;

[0094] S107. Select a laser path scanning system (in this case, a five-axis scanning galvanometer) 10 to control the first short-pulse laser beam (in this case, a nanosecond laser beam) 11 to perform removal processing according to the set scanning trajectory. After removing the covering thermal barrier ceramic coating, continue processing until the inclined part of the workpiece substrate is removed, forming a flat area 5 perpendicular to the hole axis 4. This flat area is approximately circular, and a point on the circle connects to a point on the processed surface of the workpiece substrate. The size (i.e., diameter) of this flat area is D1 = 0.6 mm. Figure 4 As shown in S1.

[0095] S201. Start coaxial air blowing until step S2 is completed;

[0096] S202. The laser processing head 20 emits a continuous fiber laser pulse train 21 to process a flat area. The average laser power is 500W and the pulse width is modulated to 20ms.

[0097] S203. The laser processing head also moves in a plane perpendicular to the hole axis;

[0098] S204. As the hole is deepened, the laser processing head 20 moves along the hole axis 4 to compensate for the focal length, ensuring that the laser energy is concentrated at the required position, until a through hole with a size D2 = Φ0.5mm is formed, such as... Figure 4 As shown in S2.

[0099] S301. The overall model of the straight circular hole is horizontally sliced ​​and layered along the hole axis with a thickness of h2 = 0.1 mm, resulting in a total of 161 layers. The contour of each layer is then extracted.

[0100] S302. Combine the described contour with the cross-sections from S1 and S2 that have already been removed to form a new shape, such as... Figure 5 As shown;

[0101] S303. Using concentric circles with an interval of d = 0.02 mm, fill the area of ​​the new graphic in S302, plan the laser scanning path, and determine the laser beam scanning trajectory;

[0102] S304. Set the laser processing parameters: laser frequency f = 100kHz, pulse width 500fs, average laser power = 100W, laser scanning speed v = 1000mm / s;

[0103] S305. Start coaxial air blowing until step S3 is completed;

[0104] S306. Select a laser path scanning system (a five-axis scanning galvanometer) 10 to control a second short-pulse laser beam (a femtosecond laser beam) 12 to remove material along the hole axis from top to bottom until a complete straight circular hole with a size D3 = Φ0.8mm is produced. Figure 4 As shown in S3.

[0105] Example 3

[0106] Example 3: An inclined straight circular hole is machined on a workpiece substrate (here, a high-temperature alloy plate) 1 with a thickness of 5 mm. The angle β between the hole axis 4 and the normal 3 of the workpiece surface is 80°. The diameter D3 of the straight circular hole is 1.2 mm, the depth is approximately 28.79 mm, and the depth-to-diameter ratio is approximately 23.99:1. A schematic diagram of the hole preparation is shown below. Figure 3 As shown, the specific steps include the following:

[0107] S101. Based on the angle α = 10° between the axis 4 of the target hole and the tangent of the workpiece surface and the removal range of 0.9 mm (D1), the model of the inclined part to be removed is obtained. The inclined part model is centered on the hole axis and the height of the inclined part model is approximately H1 = 5.10 mm.

[0108] S102. The inclined part of the model is horizontally sliced ​​and layered along the direction of the hole axis 4 with a thickness of h1 = 0.2 mm, resulting in 26 layers. Each layer represents a cross-sectional profile of the model at that location. The profile of each layer is extracted.

[0109] S103. The area formed by the contour is filled with cross lines at intervals of d = 0.01 mm to plan the laser scanning path and determine the laser beam scanning trajectory;

[0110] S104. Clamp the workpiece and tilt it to the machining position and machining angle;

[0111] S105. Set the laser processing parameters: laser frequency f = 60kHz, pulse width 200ns, average laser power P = 100W, and laser scanning speed v = 600mm / s;

[0112] S106. Start coaxial air blowing until step S1 is completed;

[0113] S107. Select a laser path scanning system (in this case, a five-axis scanning galvanometer) 10 to control the first short-pulse laser beam (in this case, a nanosecond laser beam) 11 to perform removal processing according to the set scanning trajectory until the inclined part of the workpiece substrate is removed, forming a flat area 5 perpendicular to the hole axis 4. This flat area is approximately circular, with the hole axis as the center, and a point on the circle connected to a point on the workpiece substrate processing surface. The size (i.e., diameter) of this flat area is D1 = 0.9 mm. Figure 3As shown in S1.

[0114] S201. Start coaxial air blowing until step S2 is completed;

[0115] S202. The laser processing head 20 emits a continuous fiber laser pulse train 21 to process a flat area. The average laser power is 600W and the pulse width is modulated to 10ms.

[0116] S203. The laser processing head also moves in a plane perpendicular to the hole axis;

[0117] S204. As the hole is deepened, the laser processing head 20 moves along the hole axis 4 to compensate for the focal length, ensuring that the laser energy is concentrated at the required position, until a through hole with a size D2 = Φ0.7mm is formed, such as... Figure 3 As shown in S2.

[0118] S301. The overall model of the rectangular hole is horizontally sliced ​​along the hole axis with a thickness of h2 = 0.1 mm, resulting in a total of 288 layers. The contour of each layer is then extracted.

[0119] S302. Combine the described contour with the cross-sections from S1 and S2 that have already been removed to form a new shape, such as... Figure 5 As shown;

[0120] S303. Using concentric circles with an interval of d = 0.01 mm, fill the area of ​​the new graphic in S302 to plan the laser scanning path and determine the laser beam scanning trajectory;

[0121] S304. Set the laser processing parameters: laser frequency f = 80kHz, pulse width 400fs, average laser power = 150W, laser scanning speed v = 1200mm / s;

[0122] S305. Start coaxial air blowing until step S3 is completed;

[0123] S306. Select a laser path scanning system (a five-axis scanning galvanometer) 10 to control a second short-pulse laser beam (a femtosecond laser beam) 12 to remove material along the hole axis from top to bottom until a complete straight circular hole with a size D3 = 1.2mm is produced. Figure 3 As shown in S3.

[0124] All aspects, embodiments, and features of this invention should be considered illustrative in all respects and not limiting of the invention; the scope of the invention is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0125] In the preparation method of this invention, the order of the steps is not limited to the listed order. For those skilled in the art, variations in the order of the steps without creative effort are also within the scope of protection of this invention. Furthermore, two or more steps or actions can be performed simultaneously.

[0126] Finally, it should be noted that the specific embodiments described herein are merely illustrative examples of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them; it is neither necessary nor possible to exemplify all embodiments here. However, these obvious variations or modifications derived from the essential spirit of the invention still fall within the scope of protection of the invention, and interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A laser composite processing method for inclined deep holes, characterized in that, Includes the following steps: S1. The laser path scanning system controls a first short-pulse laser beam to remove the workpiece layer by layer from top to bottom along the hole axis until the inclined part of the workpiece is removed to form a flat area perpendicular to the hole axis. The size of the flat area is smaller than the minimum cross-sectional size of the target hole. S2. The laser processing head emits a long pulse laser beam pulse train to process in a flat area, forming a through hole with a diameter smaller than the minimum cross-sectional size of the target hole; S3. The laser path scanning system controls a second short-pulse laser beam to remove material along the hole axis from top to bottom until a complete hole that perfectly matches the three-dimensional dimensions of the target hole is produced.

2. The laser composite processing method for inclined deep holes according to claim 1, characterized in that, When the workpiece is a substrate and is not covered with a thermal barrier ceramic coating, step S1 includes the following sub-steps: S101. Determine the model of the inclined part to be removed based on the angle α between the axis of the target hole and the tangent of the workpiece surface, as well as the size of the flat area. S102. Slice the inclined part of the model into layers along the direction of the hole axis and extract the contour of each layer; S103. Fill the area formed by the contour, plan the laser scanning path, and determine the laser beam scanning trajectory; S104. Clamp the workpiece and tilt it to the machining position and machining angle; S105. Set laser processing parameters; S106. Turn on the coaxial water flow or coaxial air blowing; S107. The laser path scanning system controls the first short pulse laser beam to perform removal processing according to the set scanning trajectory until the inclined part of the workpiece is removed to form a flat area perpendicular to the hole axis, and a point on the flat area is connected to a point on the workpiece processing surface. When the workpiece is a workpiece substrate with a surface covered by a thermal barrier ceramic coating, step S1 includes the following sub-steps: S101. Determine the model of the inclined part to be removed based on the angle α between the axis of the target hole and the tangent of the workpiece surface, as well as the size of the flat area. S102. Slice the inclined part of the model into layers along the direction of the hole axis and extract the contour of each layer; S103. Fill the area formed by the contour, plan the laser scanning path, and determine the laser beam scanning trajectory; S104. Clamp the workpiece and tilt it to the machining position and machining angle; S105. Set laser processing parameters; S106. Turn on the coaxial water flow or coaxial air blowing; S107. The laser path scanning system controls the first short pulse laser beam to perform removal processing according to the set scanning trajectory. After removing the covering thermal barrier ceramic coating, the processing continues until the inclined part of the workpiece substrate is removed to form a flat area perpendicular to the hole axis. A point on the flat area is connected to a point on the processing surface of the workpiece substrate.

3. The laser composite processing method for inclined deep holes according to claim 2, characterized in that, The inclined part of the model is centered on the axis of the hole, and the flat area formed is also centered on the axis of the hole. And / or, in step S103, the area formed by the contour is filled at certain intervals using any one of the following methods: cross, concentric circles, or spiral.

4. The laser composite processing method for inclined deep holes according to claim 1, characterized in that, Step S2 includes the following sub-steps: S201. Start coaxial air blowing; S202. The long pulse laser beam emitted by the laser processing head performs processing in a flat area; S203. The laser processing head moves in a plane perpendicular to the hole axis; S204. As the hole is penetrated deeper, the laser processing head moves along the hole axis to compensate for the focal length until a through hole with a diameter smaller than the minimum cross-sectional size of the target hole is formed.

5. The laser composite processing method for inclined deep holes according to claim 1, characterized in that, Step S3 includes the following sub-steps: S301. Slice the overall model of the target hole into layers along the hole axis and extract the contour of each layer; S302. Form a new shape by combining the outline with the cross-sections that have been removed in steps S1 and S2; S303. Fill the area of ​​the new graphic, plan the laser scanning path, and determine the laser beam scanning trajectory; S304. Set laser processing parameters; S305. Turn on the coaxial water flow or coaxial air blowing; S306. The laser path scanning system controls the second short-pulse laser beam to remove material along the hole axis from top to bottom until a complete hole that perfectly matches the three-dimensional dimensions of the target hole is produced.

6. A laser composite processing method for inclined deep holes according to any one of claims 1-3 and 5, characterized in that, The laser path scanning system is one of a five-axis scanning galvanometer, a rotary cutting system, a two-axis scanning galvanometer, and a three-axis scanning galvanometer.

7. A laser composite processing method for inclined deep holes according to any one of claims 1-3 and 5, characterized in that, The first and second short-pulse laser beams are emitted by a short-pulse laser, which can be one of a nanosecond laser, a picosecond laser, or a femtosecond laser. The pulse widths of the first and second short-pulse laser beams range from 1 fs to 1000 ns.

8. The laser composite processing method for inclined deep holes according to claim 7, characterized in that, The pulse width of the second type of short-pulse laser beam is smaller than that of the first type of short-pulse laser beam.

9. The laser composite processing method for inclined deep holes according to claim 8, characterized in that, The pulse width of the first type of short-pulse laser beam is 10–800 ns, and the pulse width of the second type of short-pulse laser beam is 10–800 fs.

10. A laser composite processing method for inclined deep holes according to claim 1 or 4, characterized in that, The laser processing head is a continuous fiber laser or a quasi-continuous fiber laser. And / or, the pulse width of the long pulse laser beam pulse train emitted by the laser processing head is 1 to 100 ms, and the power is 1 to 1000 W.

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