Design method of aircraft complex curvature skin clamp

Abstract

The invention discloses a design method of an aircraft complex curvature skin clamp, and relates to the technical field of tool design, and the design method comprises the following steps: obtaining digital-analog and hole site information of a skin part, and carrying out data sampling; generating different reference planes based on sampling information obtained by data sampling; carrying out analog calculation on all sampling information under different reference planes to obtain the reference planes and the height of the tool when the minimum volume Vmin of the tool blank is obtained; and based on the reference plane and the tool height, designing to obtain a tool digital model. According to the aircraft complex curvature skin clamp, the most suitable tool reference plane is determined by establishing an accurate model and traversing the machining characteristics of the whole model, so that the size of the tool blank is minimized on the premise of meeting the machine tool stroke, and the problem that no accurate model for determining the tool reference plane exists in the current industry is solved. The tool manufacturing cost is high due to improper selection of the tool datum plane, and the machine tool overtravel is caused due to improper setting of the tool height.

Description

Technical Field

[0001] This application relates to the field of tooling design technology, specifically to a design method for a complex curvature skin fixture for aircraft. Background Technology

[0002] Carbon fiber skin is widely used in the modern aerospace industry due to its excellent properties such as high strength, low density, shock absorption, sound absorption, and corrosion resistance.

[0003] Carbon fiber skin requires machining processes such as edge trimming and hole drilling to ensure dimensional accuracy. Vacuum milling fixtures for skin (hereinafter referred to as tooling) are currently widely used in the machining of skin. However, skin tooling has high manufacturing costs, and each tooling typically only fits one skin part, resulting in poor versatility. Against this backdrop, reasonably reducing the raw material volume of tooling is an important objective in controlling tooling manufacturing costs.

[0004] Currently, the industry is reducing the volume of tooling stock through simplified tooling structure design and modular design. However, for aircraft complex curvature skin fixtures, there is currently no accurate model in the industry to determine the tooling reference plane, which makes it impossible to minimize the volume of tooling stock, resulting in high tooling manufacturing costs and machine tool overtravel problems due to improper tooling height settings. Summary of the Invention

[0005] The main purpose of this application is to provide a design method for complex curvature skin fixtures for aircraft, aiming to solve the problems of high tooling manufacturing costs due to improper selection of tooling reference planes and machine tool overtravel caused by improper tooling height settings, which are currently not accurately modeled in the industry to determine the tooling reference plane.

[0006] The technical solution adopted in this application is as follows: A design method for a complex curvature aircraft skin jig includes the following steps: Obtain the digital model and hole position information of the skin part, and perform data sampling; Based on the sampling information obtained from data sampling, different reference planes are generated; Simulation calculations are performed on all sampled information under different reference planes to obtain the minimum volume V of the tooling blank. min Reference plane and tooling height at that time; Based on the minimum volume V of the tooling material min The reference plane and tooling height are used to design and obtain the tooling digital model.

[0007] Furthermore, the acquisition of the digital model and hole position information of the skin part, and the data sampling, includes: Import the 3D digital model of the skinned part and the normal vector information of the skinned hole position from the model database; Manual data sampling was performed on the surface to be processed, the contour, and the locations of all holes to be drilled on the skin to obtain sampling information for each target item.

[0008] Furthermore, the sampling information includes the surface to be processed of the skin part, its contour, and the coordinates (x, y, z) and normal vectors (i, j, k) of all holes to be processed in the fuselage coordinate system.

[0009] Furthermore, the sampling principle for manually sampling data on the surface of the skin to be processed is: sampling points are evenly distributed, covering the skin surface in a grid pattern, and additional sampling points are added at locations with complex curvature.

[0010] Furthermore, the sampling principle for manually sampling data on the skin contour is: sampling with a fixed step size, and adding sampling points at the sharp corners of the part.

[0011] Furthermore, the generation of different reference planes based on the sampling information obtained from data sampling includes: The sampling points on the surface to be processed of the skin part are traversed, and every three points are combined to generate an initial reference plane P0, so that the initial reference plane P0 is tangent to the part and located below the part, thereby obtaining the reference plane P.

[0012] Furthermore, the process involves simulating and calculating all sampled information under different reference planes to obtain the minimum volume V of the tooling blank. min The reference plane and tooling height at that time include: Under a certain reference plane, based on the machine tool Z-axis travel relationship during part machining, calculate the minimum value M of the machine tool Z-axis travel for that part; Based on the minimum value M of the machine tool Z-axis travel, compare it with the minimum value K of the machine tool Z-axis travel to obtain the tooling height H; Calculate the tooling material volume V based on the obtained tooling height H; Returning to the previous step, under a certain reference plane, based on the machine tool Z-axis travel relationship during part machining, calculate the minimum value M of the machine tool Z-axis travel for that part, to obtain the tooling blank volume V under all reference planes, and obtain the minimum value V of the tooling blank volume. min Among them, V min The corresponding reference plane is the reference plane that minimizes the volume of the tooling material.

[0013] Furthermore, the minimum value M of the machine tool Z-axis travel of the part is the minimum value of the Z-axis travel when the skin part is machining all features.

[0014] Further, the step of comparing the minimum value M of the machine tool Z-axis travel with the minimum value K of the machine tool Z-axis travel to obtain the tooling height H includes: If the minimum value M of the machine tool Z-axis travel is greater than the minimum value K of the machine tool Z-axis travel, the tooling height meets the processing requirements. The height h of the tooling body is the distance from the highest point of the part to the reference plane. At the same time, in order to meet the tooling support strength requirements, there is a tooling base with a thickness of a below the tooling body for support, where a is a fixed constant. At this time, the tooling consists of the tooling body and the tooling base, and the final tooling height H = h + a. If the minimum value M of the machine tool Z-axis travel is less than the minimum value K of the machine tool Z-axis, and the tooling height is insufficient, causing the machine tool Z-axis to exceed the minimum travel, the tooling body height h will be compensated. The compensation height is KM. At this time, the tooling body height is h+KM, and the final tooling height is H=(h+KM)+a.

[0015] Furthermore, the length L and width W of the tooling are set as fixed parameters according to the size of the skin, and the raw material volume of the tooling is V=H*L*W.

[0016] Compared with the prior art, the beneficial effects of this application are: This application proposes a design method for complex curvature skin jigs for aircraft. By establishing an accurate model and traversing the machining features of the entire model, the most suitable tooling reference plane is determined. This minimizes the volume of the tooling blank while satisfying the machine tool travel requirements. This solves the current industry problem of high tooling manufacturing costs due to improper tooling reference plane selection and machine tool overtravel issues caused by improper tooling body height settings, which are not yet available with an accurate model for determining the tooling reference plane. Attached Figure Description

[0017] Figure 1 The following is a flowchart of the specific method described in this invention. Figure 2 This is a schematic diagram illustrating the differences in tooling with different reference planes and tooling heights as described in this invention. Figure 3 This is a schematic diagram illustrating the machine tool spindle exceeding its travel range when the workpiece swing angle is large, as described in this invention. Figure 4 This is a schematic diagram of the Z-axis travel relationship of the machining tool during the machining of the part described in this invention; Figure 5 This is a flowchart of the algorithm for obtaining the reference plane and tooling height according to the present invention; Explanation of the labels in the attached drawings: 1-Floor, 2-Station adhesive, 3-Drainage hole, 4-Mold, 5-Mold bottom surface, 6-Vent hole, 7-Injection hole, 8-Pressure block, 9-Putty strip. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0020] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0021] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0022] Skin-covering tooling is currently widely used in the machining of skin. However, skin-covering tooling is costly to manufacture, and the industry is currently reducing tooling volume through methods such as simplifying tooling structure design and modular design. This patent proposes a method to minimize the raw material volume of tooling by rationally selecting the tooling reference plane.

[0023] like Figure 2As shown, different tooling reference surfaces result in different part placement postures, directly affecting the surface shape of the tooling and consequently the swing angle and stroke of the machine tool spindle during machining. On the other hand, if the height of the tooling body is defined as the distance from the highest point of the part placed on the tooling base to the upper surface of the tooling base, different reference surfaces determine different body heights, thus directly affecting the tooling height. (See...) Figure 3 The tooling is custom-made based on the skin parts. The length and width of the tooling blank are basically determined based on the size of the skin. Therefore, it can be concluded that the main factors affecting the volume of the tooling blank for a certain part are the selection of the reference plane and the determination of the tooling height.

[0024] Based on the above theories, such as Figure 1 As shown in the figure, this application provides a design method for a complex curvature skin jig for aircraft, including the following steps: S1: Obtain the digital model and hole position information of the skin part, and perform data sampling; S2: Based on the sampling information obtained from data sampling, different reference planes are generated; S3: Simulate and calculate all sampled information under different reference planes to obtain the minimum volume V of the tooling blank. min Reference plane and tooling height at that time; S4: Based on the minimum volume V of the tooling blank min The reference plane and tooling height are used to design and obtain the tooling digital model.

[0025] In the above embodiments, for complex curvature skin fixtures for aircraft, by acquiring the digital model and hole position information of the skin parts, the transformation from traditional experience-based design to digital modeling is realized. High-density data sampling technology is adopted to accurately capture complex surface features, establish an accurate model, traverse the machining features of the entire model, and determine the most suitable tooling reference plane. This minimizes the tooling blank volume while meeting the machine tool travel requirements, solving the current industry problem of high tooling manufacturing costs due to improper tooling reference plane selection and machine tool overtravel due to improper tooling height setting, which is caused by the lack of an accurate model to determine the tooling reference plane.

[0026] In a preferred embodiment, as described in step S1, acquiring the digital model and hole position information of the skin part, and performing data sampling, includes: Import the 3D digital model of the skinned part and the normal vector information of the skinned hole position from the model database; Manual data sampling was performed on the surface, contour, and all locations of holes to be drilled on the skin to obtain sampling information for each target item.

[0027] In the above, each target item refers to the surface to be processed of the skin, the contour, and all holes to be made. The sampling information includes the coordinates (x, y, z) and normal vectors (i, j, k) of the surface to be processed of the skin part, the contour, and all holes to be made in the fuselage coordinate system.

[0028] In this embodiment, the aim is to traverse the entire skin part to obtain as many sampling points as possible in order to obtain accurate digital model information. When performing manual data sampling, sampling points can be marked on the surface to be processed according to a grid distribution, with a focus on covering the contour edges and the area around the holes. The contour point cloud data of the skin surface is obtained using a 3D scanner. The sampling of the holes must include the coordinates of the normal endpoints and the offset data. The coordinates of the holes are collected using a contact probe, and the direction information is obtained in conjunction with a normal measurement device.

[0029] It is important to note that manual data sampling on the surface of the skin to be processed requires that sampling points be evenly distributed, forming a grid across the skin surface, with additional sampling points at areas of complex curvature. This is easily understood because: firstly, areas with drastic curvature changes often correspond to key features such as edges and corners of an object, requiring a higher density of sampling points to accurately describe their geometry; secondly, uniform sampling can lead to sparsification of feature points in high-curvature areas, and increasing the number of sampling points can prevent geometric distortion caused by insufficient sampling. Typically, this can be achieved by calculating the curvature values ​​of each point in the point cloud, automatically increasing the sampling density when the curvature exceeds a preset threshold, or by calculating the angle between the normals of neighboring points and identifying areas with angles greater than a set value (e.g., 5°) for focused sampling.

[0030] Manual data sampling for skin contours requires sampling at a fixed step size, with additional sampling points at sharp corners of the part. Similarly, sharp corner regions have infinite curvature, necessitating higher sampling density to accurately describe geometric features and avoid feature distortion due to insufficient sampling. Typically, eigenvalue analysis can be used to identify sharp corner regions and automatically add sampling points, or edge-aware resampling algorithms can be employed to automatically add sampling points at sharp feature edges.

[0031] Taking a complex curvature skin part with a size of approximately 1500mm*650mm as an example, in step S1, when sampling the surface to be processed of the skin, the grid size is generally preferably set to 200mm*200mm, and when sampling the skin contour, the step size is generally preferably set to 50mm. However, the grid size for surface sampling and the step size for contour sampling can be adjusted and optimized according to the computing power of the computer.

[0032] In a preferred embodiment, as described in step S2, different reference planes are generated based on the sampling information obtained from data sampling, including: Traverse the sampling points of the part surface in step S1, and generate an initial reference plane P0 by combining every three points. Offset the initial reference plane P0 so that it is tangent to the part and located below the part, thereby obtaining the tooling reference plane P. It is easy to see that the more sampling points in step S1, the more reference planes are generated in this step, and the more accurate the final determined minimum volume of the tooling blank is. Taking the aforementioned complex curvature skin part with dimensions of approximately 1500mm*650mm as an example, if a total of 40 sampling points are obtained on the surface of the skin part, a total of 9880 reference planes can be generated.

[0033] In the above implementation, an initial reference plane P0 is generated by three sampling points. Based on the geometric feature sampling points, the local curvature features of the part surface can be effectively captured, ensuring the correlation between the reference plane and the surface. At the same time, the initial reference plane is offset to a position tangent to the part. Tangency can accurately fit the part surface, avoiding dimensional errors caused by gaps. Furthermore, the initial reference plane is located below the part and can be used as the installation reference for the tooling fixture. The offset operation can also avoid interference with the part and ensure a safe space between the tooling and the part.

[0034] like Figure 5 As shown, in a preferred embodiment, as described in step 3, simulation calculations are performed on all sampled information under different reference planes to obtain the reference plane and tooling height when the tooling blank has a minimum volume Vmin, including: S31: Under a certain reference plane, based on the machine tool Z-axis travel relationship during part machining, calculate the minimum value M of the machine tool Z-axis travel for that part; S32: Based on the minimum value M of the machine tool Z-axis travel of the part, compare it with the minimum value K of the machine tool Z-axis travel to obtain the tooling height H; S33: Calculate the raw material volume V of the tooling based on the obtained tooling height H; S34: Returning to the previous step, based on the machine tool Z-axis travel relationship during part machining under a certain reference plane, calculate the minimum value M of the machine tool Z-axis travel for that part, to obtain the tooling blank volume V under all reference planes, and obtain the minimum value V of the tooling blank volume. min Among them, V min The corresponding reference plane is the reference plane that minimizes the volume of the tooling material.

[0035] The minimum travel of the machine tool's Z-axis refers to the maximum range of movement of the machine tool's A-axis endpoint along the Z-direction, with the machine tool's worktable plane as a reference. The minimum travel refers to the lower limit of this range. Usually, for safety and other reasons, to avoid the machine tool's A-axis end face colliding with the worktable surface, a minimum travel in the machine tool's Z-direction is set.

[0036] The minimum stroke of a part refers to the lowest point that the end face of the machine tool spindle A-axis needs to reach during part machining, such as... Figure 4As shown, the minimum travel required for part machining depends on the Z-coordinate of the part's measurement point and the swing angle θ during machining. It should be noted that the minimum travel is calculated using the actual height: that is, given a reference plane, the Z-coordinate of any measurement point on the part is equal to the height of the fixture base plus the Z-coordinate of that point relative to the reference plane. Therefore, the minimum travel described below is based on this height calculation method.

[0037] For step S31, it is conceivable that, since the skin part to be processed has a complex curvature, the machine tool spindle A-axis swing angle and Z coordinate are different for different processing points during the processing process. Therefore, the minimum value M of the machine tool Z-axis travel of the part in this step is obtained by calculating the minimum value of the Z-axis travel of all contour and hole sampling data of the part.

[0038] During machine tool processing, the fixture height H is constrained by the minimum travel range K of the machine tool's Z-axis. The minimum travel range K of the machine tool's Z-axis is the shortest distance from the end face of the machine tool's A-axis (i.e., the tool clamping point) to the machine tool's worktable. This parameter is an inherent property of the machine tool and is a fixed value. Figure 3 As shown, when the tooling height is small and the machine tool spindle swing angle is large, the machine tool Z-axis may exceed its minimum travel range. When the tooling is tall, the machine tool Z-axis will not exceed its minimum travel range, but the tooling blank volume increases significantly, which is detrimental to cost control. Therefore, to reduce tooling costs by reducing volume, it is necessary to find a design scheme that minimizes the tooling blank volume within the constraints of the machine tool Z-axis travel range.

[0039] Generally, a tooling fixture consists of a base and a body. The height of the base is usually a fixed constant, denoted as ah. In the field of skin processing, the base height is typically designed to be 50 mm. The length L and width W of the fixture are fixed parameters based on the size of the skin. The raw material volume of the fixture is V = H * L * W. Therefore, in step S32, the process of comparing the minimum value M of the machine tool Z-axis travel with the minimum value K of the machine tool Z-axis travel to obtain the fixture height H includes: If the minimum Z-axis travel M of the part is greater than the minimum Z-axis travel K of the machine tool, and the fixture height meets the machining requirements, the fixture body height h is the distance from the highest point of the part to the reference plane. Simultaneously, to meet the fixture support strength requirements, a fixture base of thickness a is provided below the fixture body for support, where a is a constant. In this case, the fixture consists of the fixture body and the fixture base, and the final fixture height H = h + a.

[0040] If the minimum Z-axis travel M of the part is less than the minimum Z-axis travel K of the machine tool, and the fixture height is insufficient, causing the Z-axis to exceed the minimum travel, the fixture body height h will be compensated for by a compensation height of KM. At this point, the fixture body height is h + KM. The final fixture height is H = (h + KM) + a. For example, if a machine tool has a minimum Z-axis travel of K=150 mm, and the part needs to be machined at a height of z=60 mm above the machine tool's worktable with an A-axis swing angle of 60°, and the tool length is L=100 mm, then the required Z-axis travel is M = z + Lcos(60°) = 110 mm. In this case, the fixture body needs to be raised by 40 mm using a compensation height KM to ensure the machining point falls within the machine tool's effective travel. Otherwise, the machine tool cannot reach the part's machining position, and thus cannot complete the machining of the part.

[0041] As can be seen, by comparing the minimum Z-axis travel (M) required for part machining with the machine tool's actual adjustable minimum travel (K), it can be determined whether the tooling needs height compensation. This logic directly solves the core problem of "how to adapt to part machining when the machine tool's travel is insufficient," avoiding collisions or machining failures caused by excessive travel.

[0042] Furthermore, the tooling adopts a split structure of base (fixed height a) + main body (adjustable height h), achieving versatility and flexibility. By default (M≥K), only a standard base is needed, simplifying tooling design; for special requirements (M<K), the height of the main body is dynamically adjusted through a compensation formula, eliminating the need to redesign the entire tooling and reducing costs. The compensation mechanism avoids machine tool alarms or shutdowns due to insufficient travel, reducing debugging time. The compensation amount (KM) is clearly defined through a mathematical formula, eliminating human estimation errors and ensuring machining position accuracy. This design is adaptable to different machine tools (different travel K values) and parts (different M values), requiring only adjustment of the compensation height to reuse the tooling base, making it particularly suitable for the production of various parts.

[0043] For step S33, after obtaining the height H of the tooling in steps S31 and S32, the volume of the tooling material under the corresponding reference plane can be obtained by using the formula V=H*L*W.

[0044] For step S34, after passing steps S31, S32 and S33, the tooling blank volume under all reference planes can be obtained. All the obtained tooling blank volumes are compared. The remaining elements of the tooling are designed based on the reference plane where the smallest tooling blank volume is located, and the tooling is manufactured.

[0045] In summary, the design method for a complex curvature skin fixture for aircraft provided in this application involves sampling and traversing to reasonably find a tooling reference plane that meets the requirements. Based on this tooling reference plane, the determined tooling height minimizes the tooling material volume while satisfying the machine tool travel. This solves the problem that the industry currently lacks an accurate model to determine the tooling reference plane, leading to high tooling manufacturing costs due to improper tooling reference plane selection and machine tool overtravel due to improper tooling height setting.

[0046] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A design method for a complex curvature skin jig for aircraft, characterized in that, Includes the following steps: Obtain the digital model and hole position information of the skin part, and perform data sampling; Based on the sampling information obtained from data sampling, different reference planes are generated; Simulation calculations are performed on all sampled information under different reference planes to obtain the minimum volume V of the tooling blank. min Reference plane and tooling height at that time; Based on the minimum volume V of the tooling material min The reference plane and tooling height are used to design and obtain the tooling digital model.

2. The design method for aircraft complex curvature skin jig according to claim 1, characterized in that, The process of acquiring the digital model and hole position information of the skin part and performing data sampling includes: Import the 3D digital model of the skinned part and the normal vector information of the skinned hole position from the model database; Manual data sampling was performed on the surface to be processed, the contour, and the locations of all holes to be drilled on the skin to obtain sampling information for each target item.

3. The design method for aircraft complex curvature skin jig according to claim 2, characterized in that, The sampling information includes the surface to be processed of the skin part, its contour, and the coordinates (x, y, z) and normal vectors (i, j, k) of all holes to be processed in the fuselage coordinate system.

4. The design method for aircraft complex curvature skin jig according to claim 2, characterized in that, The sampling principle for manually sampling data on the surface of the skin to be processed is: sampling points are evenly distributed, covering the skin surface in a grid pattern, and additional sampling points are added at locations with complex curvature.

5. The design method for aircraft complex curvature skin jig according to claim 2, characterized in that, The sampling principle for manually sampling data on the skin contour is: sampling with a fixed step size, and adding sampling points at the sharp corners of the part.

6. The design method for a complex curvature aircraft skin fixture according to claim 1, characterized in that, The sampling information obtained based on data sampling generates different reference planes, including: The sampling points on the surface to be processed of the skin part are traversed, and every three points are combined to generate an initial reference plane P0, so that the initial reference plane P0 is tangent to the part and located below the part, thereby obtaining the reference plane P.

7. The design method for a complex curvature aircraft skin fixture according to claim 1, characterized in that, The process involves simulating and calculating all sampled information under different reference planes to obtain the minimum volume V of the tooling blank. min The reference plane and tooling height at that time include: Under a certain reference plane, based on the machine tool Z-axis travel relationship during part machining, calculate the minimum value M of the machine tool Z-axis travel for that part; Based on the minimum value M of the machine tool Z-axis travel, compare it with the minimum value K of the machine tool Z-axis travel to obtain the tooling height H; Calculate the tooling material volume V based on the obtained tooling height H; Returning to the previous step, under a certain reference plane, based on the machine tool Z-axis travel relationship during part machining, calculate the minimum value M of the machine tool Z-axis travel for that part, to obtain the tooling blank volume V under all reference planes, and obtain the minimum value V of the tooling blank volume. min Among them, V min The corresponding reference plane is the reference plane that minimizes the volume of the tooling material.

8. The design method for a complex curvature aircraft skin fixture according to claim 7, characterized in that, The minimum value M of the machine tool Z-axis travel of the part is the minimum value of the Z-axis travel when the skin part is machining all features.

9. The design method for a complex curvature aircraft skin fixture according to claim 7, characterized in that, The minimum value M of the machine tool Z-axis travel based on the part is compared with the minimum value K of the machine tool Z-axis travel to obtain the fixture height H, including: If the minimum value M of the machine tool Z-axis travel is greater than the minimum value K of the machine tool Z-axis travel, and the tooling height meets the processing requirements, then the tooling consists of a tooling body and a tooling base. The height h of the tooling body is the distance from the highest point of the part to the reference plane. At the same time, in order to meet the tooling support strength requirements, there is a tooling base with a thickness of a below the tooling body for support, where a is a fixed constant. Finally, the tooling height H = tooling body height h + tooling base height a. If the minimum value M of the machine tool Z-axis travel is less than the minimum value K of the machine tool Z-axis, and the tooling height is insufficient, causing the machine tool Z-axis to exceed the minimum travel, the tooling body height h will be compensated. The compensation height is KM. At this time, the tooling body height is h+KM, and the final tooling height is H=(h+KM)+a.

10. The design method for a complex curvature aircraft skin fixture according to claim 7, characterized in that, The length L and width W of the tooling are set as fixed parameters according to the size of the skin, and the raw material volume of the tooling is V=H*L*W.

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