Robot composite drilling method and system for laminated structure based on bottom hole boundary identification and adaptive allowance compensation

Abstract

The application belongs to the technical field of robot compound machining, and discloses a laminated structure robot compound drilling method and system based on bottom hole boundary identification and adaptive allowance compensation, which comprises the following steps: establishing a machining coordinate; presetting a laser prefabricated bottom hole according to a target hole contour; forming a prefabricated bottom hole penetrating through the laminated structure; detecting or identifying the actual boundary of the prefabricated bottom hole and the boundary of the heat affected zone to obtain an actual bottom hole boundary function and a heat affected zone outer boundary function; calculating the local side milling removal allowance at different circumferential positions according to the target hole contour function, and generating an adaptive side milling compensation trajectory accordingly; and then performing side milling reaming on the prefabricated bottom hole along the compensation trajectory until the target hole is formed. The method can adaptively adjust the side milling allowance according to the actual forming deviation of the laser bottom hole and the distribution difference of the heat affected zone, avoid the heat affected zone remaining in the final hole wall, reduce the cutting load in the robot side milling stage, and improve the laminated structure drilling quality and machining stability.

Description

Technical Field

[0001] This invention belongs to the field of robotic composite machining and stacked structure hole making technology, and relates to a robotic composite hole making method and system for stacked structures based on bottom hole boundary recognition and adaptive allowance compensation. Background Technology

[0002] Laminated structures, due to their combination of the performance advantages of multiple materials, have been widely used in aerospace, rail transportation, high-end equipment, and lightweight structure manufacturing. Taking a laminated structure composed of fiber-reinforced composite materials and metal materials as an example, such components typically require the machining of a large number of connection holes and positioning holes during actual assembly. The dimensional accuracy, roundness, surface quality of the hole walls, and the integrity of the inlet and outlet edges of these holes directly affect the connection strength, fatigue life, and service reliability of the components.

[0003] Existing methods for drilling holes in multilayer structures mainly include drilling, reaming, milling, and laser drilling. While existing mechanical drilling methods can achieve relatively stable hole wall forming quality, when machining heterogeneous multilayer structures, the significant differences in the mechanical properties, thermophysical properties, and removal mechanisms of different materials can easily lead to problems such as fluctuating cutting loads, accelerated tool wear, and inconsistent hole wall damage patterns. Especially when using robotic systems for drilling, the overall stiffness of the robot is usually lower than that of a high-rigidity machine tool, making it prone to vibration under large cutting loads, which in turn affects the dimensional accuracy and surface quality of the hole.

[0004] Laser drilling offers advantages such as non-contact operation, high efficiency, and suitability for machining complex shapes, enabling rapid removal of material from the target hole. However, the bottom hole boundary after laser processing often exhibits issues such as a heat-affected zone, recasting marks, ablation edges, or localized uneven morphology, making it difficult to directly use as the final hole wall. If a fixed allowance and fixed path method are still used in subsequent mechanical reaming, it becomes difficult to accommodate the actual boundary deviations and uneven distribution of the heat-affected zone in the laser-machined bottom hole, potentially resulting in residual heat-affected zones in some areas, or causing localized overcutting and unnecessary increases in cutting load.

[0005] Existing adaptive hole-making technologies employ monitoring devices to detect the distance between the machining tool and the laminated material, thereby adjusting the tool's machining parameters. For example, Chinese patent CN104289738A (Online Monitoring Adaptive Machining Method for Hole Making in Laminated Structures) aims to improve machining results, but it does not address or solve problems such as heat-affected zones, recasting marks, and ablation edges that often exist at the boundaries of laminated materials.

[0006] Therefore, it is necessary to propose a robotic composite hole-making method that can adaptively compensate for the allowance based on the actual boundary of the laser-pre-drilled bottom hole and the distribution of the heat-affected zone. This way, the subsequent side milling trajectory is no longer determined solely by the ideal bottom hole size, but is generated based on the actual bottom hole boundary and the outer edge of the heat-affected zone. This improves the stability of robotic hole-making and the final hole quality while ensuring the removal of the heat-affected zone. Summary of the Invention

[0007] To address the problems existing in the current robotic hole-making process for stacked structures, such as actual boundary deviation of laser-drilled bottom holes, uneven distribution of heat-affected zones, difficulty in ensuring complete removal of heat-affected zones during fixed-allowance side milling, and insufficient stability of robot hole enlargement, this invention proposes a composite hole-making method for stacked structures based on bottom hole boundary recognition and adaptive allowance compensation.

[0008] This invention identifies the actual boundary of the laser-pre-formed bottom hole and the outer boundary of the heat-affected zone, establishes the correspondence between the target hole outline, the actual boundary of the bottom hole, and the outer boundary of the heat-affected zone, and generates a circumferentially variable side milling compensation trajectory accordingly. This allows the side milling removal amount to be adjusted according to the actual forming state of the bottom hole and the distribution of the heat-affected zone, thereby avoiding the heat-affected zone remaining on the final hole wall and improving the quality of robot hole making in stacked structures.

[0009] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a composite hole-making method for stacked structures using robots based on bottom hole boundary recognition and adaptive margin compensation, comprising the following steps: S1: Fix the workpiece to be processed in a stacked structure on the processing platform, establish the workpiece coordinate system, the robot processing coordinate system and the target hole coordinate system, and determine the target hole contour. The target hole contour is represented as RT(θ), where θ is the angular variable in the circumferential direction of the target hole. S2: Plan the laser pre-drilled bottom hole path according to the target hole contour RT(θ), and use a robot equipped with a laser processing end to perform closed-track cutting on the stacked structure workpiece to form a pre-drilled bottom hole through the stacked structure workpiece; the laser processing parameters include laser power P, laser cutting speed VL, auxiliary gas pressure Pg, distance H between the nozzle and the workpiece surface, and axial position F of the laser focus relative to the lower surface of the workpiece. The purpose of step S2, laser pre-drilling the pilot hole, is to quickly remove most of the material inside the target hole, reducing the material removal load in the subsequent mechanical reaming stage. This pre-drilled pilot hole does not serve as the final hole wall, but rather as the starting boundary for subsequent side milling and reaming.

[0010] S3: Detect or identify the actual boundary of the laser-prefabricated bottom hole to obtain the actual boundary R0(θ) of the prefabricated bottom hole, and detect or estimate the outer boundary of the heat-affected zone formed by laser processing to obtain the outer boundary RH(θ) of the heat-affected zone. Step S3 transforms the actual forming state of the laser-pre-formed bottom hole into the basis for generating the subsequent side milling compensation trajectory, avoiding the need to rely solely on the theoretical bottom hole size for fixed-allowance hole enlargement.

[0011] S4: Based on the target hole profile RT(θ), the actual boundary R0(θ) of the prefabricated bottom hole and the outer boundary RH(θ) of the heat-affected zone, calculate the local side milling removal allowance M(θ) at different circumferential positions, where M(θ) satisfies: after side milling, the final hole wall is located outside the outer boundary RH(θ) of the heat-affected zone, and the final hole wall is consistent with the target hole profile RT(θ). S5: Generate a robot side-milling compensation trajectory based on the local side-milling removal allowance M(θ), wherein the side-milling compensation trajectory is a circumferentially variable allowance trajectory, rather than a fixed-radius circular trajectory; For circumferential areas where the heat-affected zone (HAZ) expands significantly, the side-milling compensation trajectory increases the local material removal amount towards the target hole contour; for circumferential areas where the HAZ expands less significantly, the side-milling compensation trajectory reduces the local overcut compensation amount. This allows the subsequent side-milling and reaming process to perform differentiated material removal based on the actual condition of the laser-pre-fabricated bottom hole.

[0012] S6: A robot equipped with a milling end effector performs side milling along the side milling compensation trajectory to enlarge the pre-made bottom hole step by step, remove the laser heat-affected zone and form the target hole.

[0013] The milling cutter enters the workpiece through a pre-drilled hole and removes material pass-by-pass along the side-milling compensation path until the target hole is formed. The side-milling machining parameters include spindle speed NS, feed rate VM, axial depth of cut AP, radial width per pass AE, and number of side-milling passes K.

[0014] Preferably, the actual boundary R0(θ) of the prefabricated bottom hole is obtained by visual inspection, laser contour detection, contact measurement or offline image recognition.

[0015] Preferably, the outer boundary RH(θ) of the heat-affected zone is determined by the changes in grayscale, color, and edge morphology of the hole edge, the heat-affected zone width prediction model, or a preset process database.

[0016] In step S4, the allowance M(θ) removed by local side milling is determined according to the following relationship: M(θ) = RT(θ)-R0(θ), and RT(θ)≥RH(θ) is satisfied, where RT(θ) is the target hole contour boundary, R0(θ) is the actual boundary of the pre-made bottom hole, and RH(θ) is the outer boundary of the heat-affected zone.

[0017] Specifically, when the target hole is a circular hole, RT(θ) can represent the radius of the target hole, that is, the radius of the target hole outline; R0(θ) is the actual boundary radius of the pre-made bottom hole, and RH(θ) is the outer boundary radius of the heat-affected zone; for non-circular holes, RT(θ) represents the boundary position of the target hole outline in the corresponding angular direction.

[0018] The side milling compensation trajectory described in S5 is generated based on the local compensation amount Q(θ), which is determined based on the relationship between the outer boundary RH(θ) of the heat-affected zone and the target hole profile RT(θ).

[0019] When the outer boundary RH(θ) of the heat-affected zone is close to the target hole profile RT(θ), the side milling compensation amount at that circumferential position is increased to improve the side milling compensation accuracy at that circumferential position; when the distance between the outer boundary RH(θ) of the heat-affected zone and the target hole profile RT(θ) is greater than the preset safety margin, the side milling compensation amount at that circumferential position is reduced. That is, when there is a sufficient safety distance, the compensation intensity at that circumferential position is reduced to reduce unnecessary cutting removal.

[0020] In S6, the progressive side milling reaming includes rough reaming and fine reaming. Rough reaming removes most of the heat-affected zone near the pre-drilled bottom hole boundary, while fine reaming forms the target hole wall. The side milling compensation trajectory includes a rough reaming trajectory and a fine reaming trajectory. The radial cut width of the rough reaming trajectory is greater than that of the fine reaming trajectory, which forms the final target hole wall. A larger radial cut width is used in the rough reaming stage, while a smaller radial cut width is used in the fine reaming stage, and the final fine reaming trajectory coincides with the target hole profile RT(θ).

[0021] Furthermore, it also includes S7: Target Hole Formation and Quality Inspection. After side milling and reaming, the target hole is obtained. The target hole is then inspected for diameter, roundness, surface quality of the hole wall, and integrity of the inlet and outlet edges.

[0022] Furthermore, the side-milling compensation trajectory for subsequent holes can be corrected based on the detection results, enabling the subsequent hole-making process to have adaptive correction capabilities. When the detection results show insufficient local hole wall quality or edge integrity, the local compensation amount Q(θ), the number of side-milling passes K, the radial cutting width AE, or the feed rate VM for subsequent holes can be adjusted accordingly.

[0023] A second aspect of the present invention provides a composite robot hole-making system based on bottom hole boundary recognition and adaptive allowance compensation for a stacked structure, thereby realizing the hole-making method. The composite robot hole-making system includes: a robot body, a laser processing end effector, a milling processing end effector, a processing platform, and a control unit. The control unit is used to generate a side milling compensation trajectory based on the actual boundary R0(θ) of the pre-made bottom hole and the outer boundary RH(θ) of the heat-affected zone.

[0024] The laser processing end effector and the milling processing end effector are respectively mounted on the robot body; The laminated structure workpiece is a composite material / metal laminated structure workpiece; The composite material / metal laminated structure workpiece is a carbon fiber reinforced composite material and titanium alloy laminated structure workpiece. The laser processing parameters are set as follows: laser power P is 10000-20000 W, laser cutting speed VL is 300-600 mm / min, and auxiliary gas pressure Pg is 6-14 bar. The distance H between the nozzle and the workpiece surface is 0.2-1.0 mm, and the axial position F of the laser focus relative to the lower surface of the workpiece is -3-1 mm, where F less than 0 indicates that the laser focus is below the lower surface of the workpiece. The side milling processing parameters are set as follows: spindle speed NS is 4000-10000 r / min, feed rate VM is 60-220 mm / min, axial depth of cut AP is 0.03-0.40 mm, and the number of side milling passes K is 2-5. When the same radial cut width is used in each pass, the radial cut width AE of a single pass is determined based on the local side milling removal allowance M(θ) and the number of side milling passes K; when different radial cut widths are used in each pass, the sum of the radial cut widths of each pass is equal to the local side milling removal allowance M(θ) at the corresponding circumferential position.

[0025] During side milling and reaming, the milling cutter performs localized differential removal based on a circumferentially variable compensation trajectory, eliminating the heat-affected zone while avoiding excessive cutting in areas with minimal heat impact. By using a pass-by-pass reaming method, the cutting load per pass can be reduced, improving the stability of robotic machining and minimizing tool stress fluctuations.

[0026] Specifically, when the target hole is a circular hole, the target hole diameter D is 10-25 mm, the theoretical diameter d of the prefabricated bottom hole satisfies 0.45D-0.85D, and the single-sided allowance between the theoretical boundary of the prefabricated bottom hole and the outline of the target hole is 1.5-5.0 mm. The above dimensional parameters can be adjusted according to the thickness of the laminated structure, material combination, target hole size, robot stiffness, and the degree of heat-affected zone expansion.

[0027] The present invention has the following beneficial effects: 1. This invention no longer relies solely on the theoretical bottom hole size and fixed reaming allowance for side milling. Instead, it identifies the actual boundary R0(θ) of the pre-made bottom hole and the outer boundary RH(θ) of the heat-affected zone, generating a circumferentially variable side milling compensation trajectory to match the side milling removal amount with the actual forming state of the laser-machined bottom hole. This method reduces the risk of residual heat-affected zone or local overcutting caused by fixed-allowance reaming, improves the stability of robotic side milling, and balances laser pre-processing efficiency with mechanical finishing quality, making it suitable for high-quality hole fabrication of heterogeneous multilayer structures.

[0028] 2. Furthermore, in the side milling and reaming process of this invention, the milling cutter completes localized differential removal according to a circumferentially variable compensation trajectory, thereby removing the heat-affected zone and avoiding excessive cutting in areas with less heat impact. By using a pass-by-pass reaming method, the cutting load per pass can be reduced, the stability of robot machining can be improved, and the fluctuation of tool force can be reduced. Attached Figure Description

[0029] To more clearly illustrate the technical solutions implemented in this invention, the accompanying drawings used in this invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of this invention. Those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0030] Figure 1 This is a schematic diagram of the overall process of the method of the present invention; Figure 2 This is a schematic diagram showing the relationship between the target hole and the prefabricated bottom hole of the laminated component; Figure 3 A schematic diagram showing the matching relationship between the pre-fabricated bottom hole boundary, the heat-affected zone boundary, and the target hole profile; Figure 4 This is a schematic diagram of the robot laser-side milling composite machining system used in this invention; Among them, 1. laminated components; 2. composite materials; 3. metallic materials; 4. target hole contour; 5. laser pre-fabricated bottom hole contour; 6. laser heat-affected zone boundary; 7. milling allowance zone; 8. robot; 9. laser processing end effector; 10. milling processing end effector; 11. control unit; 12. processing platform. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The features of various aspects of the embodiments of the present invention will now be described in detail. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can also be practiced without these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples. The invention is not limited to any specific setups and methods provided below, but covers all improvements, substitutions, etc., to product structures and methods without departing from the spirit of the invention. In the various drawings and the following description, well-known structures and techniques are not shown to avoid unnecessarily obscuring the invention.

[0033] Overall implementation flow of the method of this invention: like Figures 1 to 4 As shown, this embodiment provides a robotic composite hole-making method for stacked structures based on bottom hole boundary recognition and adaptive allowance compensation. The method includes steps such as workpiece fixing and coordinate establishment, robot laser pre-drilling of bottom holes, identification of the actual boundary of the bottom hole, identification of the outer boundary of the heat-affected zone, adaptive hole-reaming allowance calculation, side-milling compensation trajectory generation, robot side-milling hole-reaming pass-by-pass, and target hole formation and detection.

[0034] First, fix the laminated component 1 on the processing platform 12, establish the workpiece coordinate system, the robot processing coordinate system and the target hole position coordinate, determine the target hole contour 4, and represent it as RT(θ).

[0035] Subsequently, a robot 8 equipped with a laser processing end effector 9 is used to perform closed-track cutting on the target hole area to form a pre-fabricated bottom hole penetrating the laminated component 1. The laser-fabricated bottom hole is used to remove material from the inside of the target hole in advance and does not directly serve as the final hole wall.

[0036] After the laser pre-drilled hole is completed, the actual boundary 5 of the pre-drilled hole is detected or identified to obtain R0(θ); at the same time, the outer boundary 6 of the heat-affected zone is detected or estimated to obtain RH(θ). The control unit 11 calculates the local side milling removal allowance M(θ) based on RT(θ), R0(θ) and RH(θ) and generates the side milling compensation trajectory.

[0037] Finally, the robot 8, equipped with the milling end 10, performs side milling along the side milling compensation trajectory to enlarge the hole step by step, thereby removing the heat-affected zone and forming a final hole wall that is consistent with the target hole profile 4.

[0038] II. Bottom Hole Boundary Identification and Allowance Calculation like Figure 2 and Figure 3As shown, after the laser-prefabricated bottom hole is formed, the actual boundary 5 of the prefabricated bottom hole may deviate locally from the theoretical prefabricated bottom hole contour due to the laser energy distribution, the difference in thermal properties of the laminated materials, the melt discharge state, and the robot trajectory error. Therefore, this invention does not directly use the theoretical bottom hole contour as the basis for side milling and hole enlargement, but obtains the actual boundary R0(θ) of the prefabricated bottom hole through detection or identification.

[0039] Meanwhile, the outer boundary 6 of the heat-affected zone may exhibit uneven distribution along the circumference. Therefore, the outer boundary RH(θ) of the heat-affected zone is obtained through image grayscale, color changes, edge morphology, or a preset model.

[0040] After obtaining RT(θ), R0(θ), and RH(θ), the control unit 11 calculates the local side milling removal allowance M(θ). When RH(θ) at a certain circumferential position is closer to RT(θ), that position requires higher side milling compensation accuracy; when the distance between RH(θ) and RT(θ) is large, the local compensation amount can be reduced to reduce unnecessary cutting.

[0041] III. Side Milling Compensation Trajectory Generation In this embodiment, the side milling compensation trajectory is not a simple fixed-radius circular trajectory, but a circumferentially variable trajectory generated based on the actual boundary of the bottom hole and the boundary of the heat-affected zone.

[0042] Side milling compensation trajectories can be divided into coarse reaming trajectories and fine reaming trajectories. Coarse reaming trajectories are mainly used to remove most of the heat-affected zone near the bottom hole boundary; fine reaming trajectories are used to ultimately form the target hole wall. For local areas where the heat-affected zone expands significantly, the side milling compensation trajectory increases the local removal amount; for local areas where the heat-affected zone expands less significantly, the side milling compensation trajectory reduces the local overcut amount.

[0043] In this way, the side milling and hole enlargement process can be adjusted differently according to the actual state of the laser-pre-drilled bottom hole, thereby avoiding the heat-affected zone remaining on the final hole wall.

[0044] like Figure 4 The diagram shown is a schematic diagram of the robot composite machining system according to an embodiment of the present invention: The robot laser-side milling composite machining system used in the present invention includes a robot body 8, a laser processing end effector 9, a milling processing end effector 10, a control unit 11, and a machining platform 12.

[0045] The laser processing end effector 9 and the milling processing end effector 10 are respectively mounted on two robots 8, and the two robots are coordinated and controlled by the control unit 11 through unified coordinate calibration. In another embodiment, the laser processing end effector 9 and the milling processing end effector 10 can be mounted on the same robot body.

[0046] The control unit 11 receives the target hole profile RT(θ), the actual boundary R0(θ) of the pre-drilled bottom hole, and the outer boundary RH(θ) of the heat-affected zone, and generates a side milling compensation trajectory. The robot 8, equipped with a milling end effector 10, completes subsequent side milling and hole enlargement according to this trajectory.

[0047] Specific embodiments applicable to composite / metal laminate structures In this embodiment, the laminated component 1 is a composite material / metal laminate, specifically a carbon fiber reinforced composite material and titanium alloy laminate structure, and the target hole is a circular hole. The target hole diameter D is set to 16 mm, the theoretical diameter d of the pre-fabricated bottom hole is 10 mm, and the single-sided allowance between the theoretical boundary of the pre-fabricated bottom hole and the outline of the target hole is 3 mm.

[0048] First, the stacked workpiece is fixed on the machining platform, and a workpiece coordinate system and a robot machining coordinate system are established. The robot, equipped with a laser processing end effector, performs closed-path cutting on the target hole area to form a pre-fabricated bottom hole penetrating the stacked structure. In this embodiment, the laser power P is 16000 W, the laser cutting speed VL is 480 mm / min, the auxiliary gas pressure Pg is 11 bar, the distance H between the nozzle and the workpiece surface is 0.6 mm, and the axial position F of the laser focus relative to the lower surface of the workpiece is -1.5 mm.

[0049] After the laser-pre-drilled bottom hole is completed, the actual boundary of the pre-drilled bottom hole is identified to obtain R0(θ); at the same time, the outer boundary of the heat-affected zone is identified or estimated to obtain RH(θ). Based on the target hole profile RT(θ), the actual boundary of the pre-drilled bottom hole R0(θ), and the outer boundary of the heat-affected zone RH(θ), the control unit calculates the local side milling removal allowance M(θ) at different circumferential positions and generates the side milling compensation trajectory.

[0050] Subsequently, a robot equipped with a milling end mill was used to perform sequential side milling to enlarge the pre-fabricated bottom hole. In this embodiment, the spindle speed NS was 8000 r / min, the feed rate VM was 150 mm / min, the axial depth of cut AP was 0.12 mm, and the number of side milling passes K was 4. Each pass adopted a graded radial width cutting method, where the first pass was used to rough remove the main heat-affected zone near the boundary of the pre-fabricated bottom hole, the second and third passes were used to gradually approach the target hole contour, and the fourth pass was used to form the final hole wall.

[0051] Under nominal machining conditions, the radial cutting widths of the four passes can be set to 1.0 mm, 0.8 mm, 0.7 mm, and 0.5 mm, respectively. When the outer boundary RH(θ) of the heat-affected zone at a certain circumferential position is close to the target hole profile RT(θ), the control unit performs local compensation on the side milling trajectory at that circumferential position to completely remove the heat-affected zone. When there is a large safety distance between the outer boundary RH(θ) of the heat-affected zone at a certain circumferential position and the target hole profile RT(θ), the control unit reduces the compensation amount at that position to reduce local overcutting and unnecessary cutting load.

[0052] After side milling and reaming, the final hole wall is formed by mechanical side milling, and the heat-affected zone generated by laser pre-machining is removed. Subsequently, the target hole is inspected for diameter, roundness, hole wall surface quality, and the integrity of the inlet and outlet edges to confirm that the target hole meets the machining requirements.

[0053] Test results When using the method described in this invention for robotic composite hole making of stacked structures, laser pre-drilling of the bottom hole is used to quickly remove material from the interior of the target hole, while side milling and reaming are used to remove the heat-affected zone and form the final hole wall. Compared with methods that fix the bottom hole size and the reaming allowance, this invention can generate a circumferentially variable compensation trajectory based on the actual boundary of the bottom hole and the outer boundary of the heat-affected zone, thereby reducing heat-affected zone residue, local overcutting, and unnecessary cutting loads, and improving the stability of robotic hole making and the quality of the final hole.

[0054] It should be noted that the logical modules constituting the system can be combined and applied to varying degrees. For the sake of simplicity, the implementation methods of various combinations will not be elaborated further. Those skilled in the art can flexibly adjust or combine the functions of the method of the present invention according to the actual situation. The functional components shown in the above embodiments can also be implemented in hardware, software, or a combination of both.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A composite hole-making method for stacked structures using robots based on bottom hole boundary recognition and adaptive margin compensation, characterized in that, Includes the following steps: S1: Fix the workpiece to be processed in a stacked structure on the processing platform, establish the workpiece coordinate system, the robot processing coordinate system and the target hole coordinate system, and determine the target hole contour. The target hole contour is represented as RT(θ), where θ is the angular variable in the circumferential direction of the target hole. S2: Plan the laser pre-drilled bottom hole path according to the target hole contour RT(θ), and use a robot equipped with a laser processing end to cut the stacked structure workpiece in a closed trajectory to form a pre-drilled bottom hole that penetrates the stacked structure workpiece; S3: Detect or identify the actual boundary of the laser-prefabricated bottom hole to obtain the actual boundary R0(θ) of the prefabricated bottom hole, and detect or estimate the outer boundary of the heat-affected zone formed by laser processing to obtain the outer boundary RH(θ) of the heat-affected zone. S4: Based on the target hole profile RT(θ), the actual boundary R0(θ) of the prefabricated bottom hole and the outer boundary RH(θ) of the heat-affected zone, calculate the local side milling removal allowance M(θ) at different circumferential positions, where M(θ) satisfies: after side milling, the final hole wall is located outside the outer boundary RH(θ) of the heat-affected zone, and the final hole wall is consistent with the target hole profile RT(θ). S5: Generate robot side milling compensation trajectory based on the local side milling removal allowance M(θ). The side milling compensation trajectory is a circumferential variable allowance trajectory, rather than a fixed radius circular trajectory. S6: A robot equipped with a milling end effector performs side milling along the side milling compensation trajectory to enlarge the pre-made bottom hole step by step, remove the laser heat-affected zone and form the target hole.

2. The hole-making method according to claim 1, characterized in that, The laser processing parameters mentioned in step S2 include laser power P, laser cutting speed VL, auxiliary gas pressure Pg, distance H between the nozzle and the workpiece surface, and axial position F of the laser focus relative to the lower surface of the workpiece.

3. The hole-making method according to claim 1, characterized in that, The side milling parameters in step S6 include spindle speed NS, feed rate VM, axial depth of cut AP, single-pass radial width of cut AE, and number of side milling passes K.

4. The hole-making method according to claim 1, characterized in that, The method also includes a target hole quality inspection step: inspecting the target hole for hole diameter, roundness, hole wall surface quality, and the integrity of the inlet and outlet edges; and correcting the side milling compensation trajectory of subsequent hole positions based on the inspection results, so that the subsequent hole making process has adaptive correction capability.

5. The hole-making method according to claim 1, characterized in that, The actual boundary R0(θ) of the prefabricated bottom hole is obtained through visual inspection, laser contour detection, contact measurement or offline image recognition.

6. The hole-making method according to claim 1, characterized in that, The outer boundary RH(θ) of the heat-affected zone is determined by the changes in grayscale, color, and edge morphology of the hole edge, the heat-affected zone width prediction model, or a preset process database.

7. The hole-making method according to claim 1, characterized in that, The allowance M(θ) removed by local side milling is determined according to the following relationship: M(θ) = RT(θ)-R0(θ), and RT(θ)≥RH(θ), where RT(θ) is the target hole contour boundary, R0(θ) is the actual boundary of the pre-made bottom hole, and RH(θ) is the outer boundary of the heat-affected zone.

8. The hole-making method according to claim 1, characterized in that, The side milling compensation trajectory in step S5 is generated based on the local compensation amount Q(θ), which is determined based on the relationship between the outer boundary RH(θ) of the heat-affected zone and the target hole profile RT(θ).

9. The hole-making method according to claim 8, characterized in that, When the outer boundary RH(θ) of the heat-affected zone approaches the target hole profile RT(θ), increase the side milling compensation amount at that circumferential position; when the distance between the outer boundary RH(θ) of the heat-affected zone and the target hole profile RT(θ) is greater than the preset safety margin, decrease the side milling compensation amount at that circumferential position.

10. The hole-making method according to claim 1, characterized in that, Step S6 involves side milling and reaming the hole, which includes rough reaming and fine reaming. Rough reaming is used to remove most of the heat-affected zone near the boundary of the pre-made bottom hole, while fine reaming is used to form the target hole wall.

11. The hole-making method according to claim 10, characterized in that, The final reaming trajectory in the fine reaming stage is consistent with the target hole profile RT(θ).

12. A composite hole-making system for stacked structures based on bottom hole boundary recognition and adaptive margin compensation, characterized in that, According to any one of claims 1-11, the robot composite hole-making system comprises: a robot body, a laser processing end effector, a milling processing end effector, a processing platform, and a control unit; the control unit is used to generate a side milling compensation trajectory based on the actual boundary R0(θ) of the pre-made bottom hole and the outer boundary RH(θ) of the heat-affected zone; The laser processing end effector and the milling end effector are respectively mounted on the robot body; the laminated workpiece is a composite material / metal laminated workpiece.

13. The hole-making system according to claim 1, characterized in that, The composite material / metal laminated structure workpiece is a carbon fiber reinforced composite material and titanium alloy laminated structure workpiece.

14. The hole-making system according to claim 13, characterized in that, The laser processing parameters are set as follows: The laser power P is 10000-20000 W, the laser cutting speed VL is 300-600 mm / min, the auxiliary gas pressure Pg is 6-14 bar, the distance H between the nozzle and the workpiece surface is 0.2~1.0 mm, and the axial position F of the laser focus relative to the lower surface of the workpiece is -3~1 mm, where F less than 0 indicates that the laser focus is located below the lower surface of the workpiece.

15. The hole-making system according to claim 13, characterized in that, The side milling parameters include spindle speed NS, feed rate VM, axial depth of cut AP, single-pass radial width AE, and number of side milling passes K; wherein, the spindle speed NS is 4000-10000 r / min, the feed rate VM is 60-220 mm / min, the axial depth of cut AP is 0.03-0.40 mm, and the number of side milling passes K is 2-5 times; when the same radial width is used in each pass, the single-pass radial width AE is determined based on the local side milling removal allowance M(θ) and the number of side milling passes K; when different radial widths are used in each pass, the sum of the radial widths of each pass is equal to the local side milling removal allowance M(θ) at the corresponding circumferential position.

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