Machining methods for metal connectors used in large composite propellers

Abstract

This invention discloses a method for machining metal connectors for large composite propellers. Specifically, the method involves removing the cap of a casting to obtain a blank; welding positioning base points onto the surface of the blank; determining the coordinate values ​​and machining allowances for each positioning base point; rough machining of the blank; aging treatment before semi-finishing and determining the semi-finishing allowance; semi-finishing the blank; aging treatment before finishing and determining the finishing allowance; non-destructive testing; finishing the blank; machining the concave surface and the screw holes on both sides; countersunk hole machining; and machining the A and B end faces. By creating a clamping fixture, the blank is tightly fitted during machining, facilitating clamping and alignment. During rough machining, a reference plane is machined and positioning pin holes are bored and milled, serving as the alignment reference for subsequent semi-finishing and finishing, thus improving machining accuracy. This machining method can be widely applied to the manufacture of various connectors between propeller hubs and blades, improving machining accuracy and enabling product interchangeability, thus facilitating mass production.

Description

Technical Field

[0001] This invention belongs to the field of marine propeller manufacturing technology, specifically relating to a method for processing metal connectors for large composite material propellers. Background Technology

[0002] Propellers are a crucial component of ship propulsion systems. Compared to traditional copper alloy and cast steel propellers, composite material propellers offer advantages such as lightweight, high strength, and corrosion resistance. Furthermore, composite material propellers excel in improving propulsion efficiency and reducing noise, and are currently commonly used in the propulsion systems of small vessels. The machining process for traditional copper alloy propellers mainly includes: cutting the cap, machining the small end face, rough machining the shaft hole, machining the pressure surface blades, machining the large end face, precision machining the shaft hole, machining the suction surface blades, non-destructive testing, pre-assembly, and static balance testing.

[0003] like Figure 6 The diagram shows the assembly of a large composite material propeller with a copper alloy hub, including an upper cover plate 1, an upper gasket 2, six metal connectors 3, six metal connector bosses 4, a lower gasket 5 (1 piece), a lower cover plate 6 (1 piece), and a copper alloy hub 7. The difficulty in machining large composite material propellers lies in the fact that the metal connectors and metal connector bosses are irregularly shaped parts, making it difficult to clamp and correct the curved surfaces of the workpieces. Furthermore, the assembly gaps between the structural components are small due to the primary connection via bolts, requiring high machining precision. Therefore, traditional machining methods are not suitable for the mass production of large composite material propellers. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems and provide a method for processing metal connectors for large composite material propellers. This method not only simplifies the workpiece clamping and correction process, but also improves the processing accuracy to enhance product interchangeability and enable mass production of the product.

[0005] To achieve the above objectives, the present invention provides a method for machining metal connectors for large composite material propellers. The machining method includes: 1) removing the cap of a casting to obtain a blank; 2) welding positioning base points on the surface of the blank; 3) providing the coordinate values ​​and machining allowances of each positioning base point; 4) rough machining of the blank; 5) aging treatment before semi-finishing and determining the semi-finishing allowance; 6) semi-finishing the blank; 7) aging treatment before finishing and determining the finishing allowance; 8) non-destructive testing; 9) finishing the blank; 10) machining the concave surface and the screw holes and countersunk holes on both sides; and 11) machining the A and B end faces.

[0006] Furthermore, the tooling used in processing the metal connectors includes a Type I concave clamping fixture and a Type II convex clamping fixture. The Type I concave clamping fixture includes a clamping base, a support frame welded to the clamping base, and a Type I blank fitting part welded to the support frame. Each end of the Type I blank fitting part has a clamping position machined thereon, and the outer surface of the Type I blank fitting part is consistent with the convex surface of the blank. The Type II convex clamping fixture includes a clamping base, a support frame welded to the clamping base, and a Type II blank fitting part welded to the support frame. Each end of the Type II blank fitting part has a clamping position machined thereon, and the outer surface of the Type II blank fitting part is consistent with the concave surface of the blank.

[0007] Furthermore, in step 2), a conical or pin-type probe is selected, and the welding material and base point material are the same as the material of the metal connector; when positioning the welding position, they are evenly distributed on the surface of the blank, and the number of positioning base points is 3 to 6.

[0008] Furthermore, in step 3), the blank is scanned to form a three-dimensional model, which is then fitted with the theoretical three-dimensional model of the metal connector. The machining allowance of each part is evenly distributed, and the coordinate values ​​of each positioning base point are given.

[0009] Further, in step 4), the rough machining of the concave surface of the blank is as follows: the type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. The clamping positions are used to clamp the blank at both ends A and B. The coordinate values ​​of each positioning base point are measured, and the blank is corrected according to the coordinate values ​​of each positioning base point after 3D scanning fitting. The gap between the convex surface of the blank and the type I blank fitting part of the type I concave surface clamping fixture is adjusted by shims. Then, the concave surface and the outline of both sides of the blank are rough machined by a three-axis CNC boring and milling machine according to the 3D model with a 3-4mm allowance on one side. The positioning end plane of the type I concave surface clamping fixture is bored and milled at both ends of the fitting part of the type I blank, and the positioning hole of the type I concave surface clamping fixture is machined on the positioning end plane of the type I concave surface clamping fixture.

[0010] Machining of positioning datum: Weld datum blocks to ends A and B of the blank respectively, machine positioning datum planes on the datum blocks and bore and mill positioning pin holes;

[0011] Rough machining of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank mating part of the Type II convex surface clamping fixture. According to the positioning datum plane on the datum block and the positioning end on the Type II convex surface clamping fixture, clamp and align the A and B ends of the blank. Adjust the gap between the concave surface of the blank and the mating part of the Type II blank of the Type II convex surface clamping fixture using shims. Then, use a three-axis CNC boring and milling machine to rough machine the convex surface of the blank according to the three-dimensional model, leaving a 3-4mm allowance on one side. Then, bore and mill the positioning end plane of the Type II convex surface clamping fixture at both ends of the mating part of the Type II blank, and machine the positioning hole of the Type II convex surface clamping fixture on the positioning end plane of the Type II convex surface clamping fixture.

[0012] Further, in step 6), the concave surface and the outline of the two sides of the blank are semi-finished: the type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. The clamping positions clamp the A and B ends of the blank. According to the positioning reference plane on the reference block and the positioning hole of the type I concave surface clamping fixture, the gap between the convex surface of the blank and the fitting part of the type I blank of the type I concave surface clamping fixture is adjusted by shims; then, the concave surface and the outline of the two sides of the blank are semi-finished by a five-axis CNC boring and milling machine according to the three-dimensional model with a single-sided allowance of 0.3 to 0.5 mm.

[0013] Semi-finishing of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank contact part of the Type II convex surface clamping fixture. According to the positioning datum plane on the datum block and the positioning hole of the Type II convex surface clamping fixture, clamp the A and B ends of the blank and align them. Adjust the gap between the concave surface of the blank and the Type II blank contact part of the Type II convex surface clamping fixture using shims. Then, use a five-axis CNC boring and milling machine to semi-finish the convex surface of the blank according to the three-dimensional model, leaving a 0.3-0.5mm allowance on each side.

[0014] Further, in step 9), the concave surface and the outline of the two sides of the blank are precision machined: the type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. According to the positioning reference plane on the reference block and the positioning hole of the type I concave surface clamping fixture, the A and B ends of the blank are clamped. The gap between the convex surface of the blank and the fitting part of the type I blank of the type I concave surface clamping fixture is adjusted by shims. Then, the concave surface and the outline of the two sides of the blank are precision machined using a five-axis CNC boring and milling machine according to the three-dimensional model. After the machining is completed, the positioning reference on the reference block at both ends A and B is transferred to the concave surface of the blank as the clamping reference for the subsequent flat A and B end planes.

[0015] Finishing of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank contact part of the Type II convex surface clamping fixture. According to the positioning datum plane on the datum block and the positioning hole of the Type II convex surface clamping fixture, align the A and B ends of the clamping position of the blank. Adjust the gap between the concave surface of the blank and the contact part of the Type II blank of the Type II convex surface clamping fixture using shims. Then, semi-finish the convex surface of the blank using a five-axis CNC boring and milling machine according to the three-dimensional model. After the machining is completed, transfer the positioning datum on the datum blocks at both ends A and B to the convex surface of the blank, as the clamping datum for the subsequent flat A and B end planes.

[0016] Further, in step 10), the type I concave clamping fixture is clamped on the worktable, and the blank is placed with the concave side facing up and the convex side facing down on the type I blank fitting part of the type I concave clamping fixture. Based on the positioning reference plane on the reference block and the positioning hole of the type I concave clamping fixture, the center coordinates of each machining screw hole and countersunk hole are given in combination with the three-dimensional model. Then, the screw holes and countersunk holes are machined using a five-axis CNC boring and milling machine.

[0017] Further, in step 11), the concave and convex surfaces of the blank are clamped and aligned using the positioning reference of the concave and convex surfaces. The gap between the blank and the fixture is adjusted by shims, and the end faces of both ends A and B are machined using a three-axis CNC boring and milling machine to obtain the metal connector.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) The present invention makes it easy to clamp and correct the blank by using two sets of clamping fixtures (Type I concave clamping fixture and Type II convex clamping fixture).

[0020] 2) In the roughing process, reference blocks are welded to both ends A and B of the blank, and positioning reference planes and positioning pin holes are machined as correction references for subsequent semi-finishing and finishing. In subsequent machining processes, it is easier to restore the machining references, and the unified machining references improve the machining accuracy of the workpiece.

[0021] 3) The present invention has tooling positioning holes machined in both the Type I concave clamping fixture and the Type II convex clamping fixture, which, together with the positioning reference planes and positioning pin holes at both ends of the blank A and B, further improves the machining accuracy and realizes the interchangeability of the products;

[0022] 4) The metal connector of the large composite material propeller processed by this invention has been successfully applied to the manufacture of the first large composite material propeller in China. The propeller has a diameter of 3m and can be divided into left and right rotation directions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the metal connector structure of the present invention;

[0024] Figure 2 for Figure 1 A schematic diagram of direction C;

[0025] Figure 3 for Figure 1 A schematic diagram of direction D;

[0026] Figure 4 This is a schematic diagram of the concave clamping fixture structure of the present invention (Type I).

[0027] Figure 5 This is a schematic diagram of the Type II convex clamping fixture structure of the present invention;

[0028] Figure 6 A schematic diagram of the assembly of a large composite material propeller with a copper alloy hub. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1-3 The metal connector shown is a spatially twisted curved irregular part, including an A-end plane 8, a B-end plane 9, a convex surface 10, a concave surface 11, a side surface I 12, and a side surface II 13. The A-end plane and the B-end plane are parallel horizontal surfaces. The A-end plane is bolted to the lower cover plate during assembly and is located on the side of the large end face of the propeller; the B-end plane is bolted to the upper cover plate during assembly and is located on the side of the small end face of the propeller. The side surface I of the metal connector has four threaded holes, which are connected to the composite material blades during assembly. The side surface II of the metal connector has three grooves, each with two threaded holes, which are bolted to the boss during assembly. The concave surface of the metal connector has four countersunk holes with an inwardly concave arc surface, which are bolted to the copper alloy propeller hub during assembly. The convex surface of the metal connector has an outwardly convex arc surface. During casting, the casting cap is located on the A-end plane.

[0031] The tooling used in machining metal connectors includes Type I concave clamping tooling and Type II convex clamping tooling; such as Figure 4 The type I concave clamping fixture shown includes a clamping base 15, a support frame 16 welded to the clamping base 15, and a type I blank fitting portion 17 welded to the support frame 16. Each end of the type I blank fitting portion 17 has a clamping position 18 machined thereon. The outer surface of the type I blank fitting portion 17 is consistent with the convex surface of the blank. Similarly, as... Figure 5The type II convex clamping fixture shown includes a clamping base 15, a support frame 16 welded to the clamping base 15, and a type II blank fitting part 20 welded to the support frame 16. Each end of the type II blank fitting part 20 is machined with a clamping position 18, and the outer surface of the type II blank fitting part 20 is consistent with the concave surface of the blank.

[0032] The specific processing method for metal connectors used in large composite material propellers according to the present invention is as follows:

[0033] 1) Remove the cap of the casting to obtain the blank.

[0034] A horizontal water-cooled wire saw was used to remove the cap opening of the casting;

[0035] 2) Weld positioning base points onto the surface of the blank.

[0036] Select a conical or pin-type probe, and ensure that the welding material and base point material are the same as those of the metal connector. When positioning the welding position, the probes should be distributed as evenly as possible on the surface of the blank, with 3 to 6 positioning base points.

[0037] 3) Provide the coordinate values ​​and machining allowances of each positioning reference point.

[0038] The blank is scanned to form a three-dimensional model, which is then fitted with the theoretical three-dimensional model of the metal connector. The machining allowances of each part are evenly distributed, and the coordinate values ​​of each positioning base point are given.

[0039] 4) Rough machining of blank parts

[0040] Rough machining of the concave surface of the blank: Clamp the Type I concave surface clamping fixture on the worktable, and place the blank with the concave surface facing up and the convex surface facing down on the Type I blank fitting part 17 of the Type I concave surface clamping fixture. Clamp the blank at both ends A and B. Measure the coordinate values ​​of each positioning base point, and correct the blank to an error of ≤0.05mm based on the coordinate values ​​of each positioning base point after 3D scanning fitting. Adjust the gap between the convex surface of the blank and the Type I blank fitting part 17 of the Type I concave surface clamping fixture using shims. Then, use a three-axis CNC boring and milling machine to rough machine the concave surface and the outline of both sides of the blank according to the 3D model, leaving a 3-4mm allowance on each side. Bor and mill the positioning end plane 19 of the Type I concave surface clamping fixture at both ends of the Type I blank fitting part 17, and machine the positioning holes of the Type I concave surface clamping fixture on the positioning end plane 19 of the Type I concave surface clamping fixture.

[0041] Positioning datum machining: Weld datum blocks to ends A and B of the blank respectively, machine the positioning datum plane on the datum block and bore and mill the positioning pin hole; This positioning datum plane and positioning pin hole serve as the datum for subsequent semi-finishing and finishing. Check the datum each time it is machined, repeat the positioning accuracy, and use it as the machining datum for the three-dimensional model.

[0042] Rough machining of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank fitting part 20 of the Type II convex surface clamping fixture. According to the positioning reference plane on the reference block and the positioning end on the Type II convex surface clamping fixture, clamp the A and B ends of the blank and align the error ≤0.05mm. Adjust the gap between the concave surface of the blank and the Type II blank fitting part 20 of the Type II convex surface clamping fixture using shims. Then, use a three-axis CNC boring and milling machine to rough machine the convex surface of the blank according to the three-dimensional model, leaving a 3-4mm allowance on one side. Then, bore and mill the positioning end plane 21 of the Type II convex surface clamping fixture at both ends of the Type II blank fitting part 20, and machine the positioning hole of the Type II convex surface clamping fixture on the positioning end plane 21 of the Type II convex surface clamping fixture.

[0043] 5) Aging treatment before semi-finishing and determination of semi-finishing allowance.

[0044] Considering the high machining accuracy of the blank and the small assembly gap, the blank needs to be aged to release residual stress and determine the semi-finishing allowance.

[0045] 6) Semi-finished blanks

[0046] Semi-finishing of the concave surface and two side contours of the blank: The type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part 17 of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. The clamping positions clamp the A and B ends of the blank. According to the positioning reference plane on the reference block and the positioning hole of the type I concave surface clamping fixture, the gap between the convex surface of the blank and the type I blank fitting part 17 of the type I concave surface clamping fixture is adjusted by shims; then, the concave surface and two side contours of the blank are semi-finished by a five-axis CNC boring and milling machine according to the three-dimensional model, leaving a 0.3-0.5mm allowance on each side.

[0047] Semi-finishing of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank contact part 20 of the Type II convex surface clamping fixture. According to the positioning reference plane on the reference block and the positioning hole of the Type II convex surface clamping fixture, clamp the A and B ends of the blank and align them. Adjust the gap between the concave surface of the blank and the Type II blank contact part 20 of the Type II convex surface clamping fixture using shims. Then, use a five-axis CNC boring and milling machine to semi-finish the convex surface of the blank according to the three-dimensional model, leaving a 0.3-0.5mm allowance on each side.

[0048] 7) Aging treatment before finishing and determination of finishing allowance

[0049] Aging treatment is performed, and the blank is left for a period of time to release residual stress. Then, the blank is put back on the machine tool to check the deformation of each part according to the three-dimensional model, determine the finishing allowance, and mark it on the physical object.

[0050] 8) Non-destructive testing

[0051] The entire blank is subjected to dye penetrant testing, and surface defects of the blank are treated in accordance with relevant standards.

[0052] 9) Finishing the blank parts

[0053] Finishing the concave surface and side contours of the blank: Clamp the type I concave surface clamping fixture on the worktable, and place the blank with the concave surface facing up and the convex surface facing down on the type I blank fitting part 17 of the type I concave surface clamping fixture. According to the positioning datum plane on the datum block and the positioning hole of the type I concave surface clamping fixture, clamp the A and B ends of the blank. Adjust the gap between the convex surface of the blank and the type I blank fitting part 17 of the type I concave surface clamping fixture using shims. Then, according to the three-dimensional model, finish machining the concave surface and side contours of the blank using a five-axis CNC boring and milling machine. After machining, transfer the positioning datum on the datum block at both ends A and B to the concave surface of the blank as the clamping datum for subsequent flat A and B end planes.

[0054] Finishing of the convex surface of the blank: Clamp the Type II convex surface clamping fixture on the worktable, and place the blank with the concave side down and the convex side up on the Type II blank contact part 20 of the Type II convex surface clamping fixture. According to the positioning datum plane on the datum block and the positioning hole of the Type II convex surface clamping fixture, align the clamping positions at both ends A and B of the blank. Adjust the gap between the concave surface of the blank and the Type II blank contact part 20 of the Type II convex surface clamping fixture using shims. Then, semi-finish the convex surface of the blank using a five-axis CNC boring and milling machine according to the three-dimensional model. After the machining is completed, transfer the positioning datum on the datum blocks at both ends A and B to the convex surface of the blank, as the clamping datum for the subsequent flat A and B end planes.

[0055] 10) Machining of concave surfaces and screw holes and countersunk holes on both sides

[0056] The Type I concave clamping fixture is clamped on the worktable, and the blank is placed with the concave side facing up and the convex side facing down on the Type I blank fitting part 17 of the Type I concave clamping fixture. Based on the positioning reference plane on the reference block and the positioning hole of the Type I concave clamping fixture, the center coordinates of each machining screw hole and countersunk hole are given in combination with the three-dimensional model. Then, the screw holes and countersunk holes are machined using a five-axis CNC boring and milling machine.

[0057] 11) Machining of end faces A and B

[0058] Clamp the concave and convex sides of the blank, use the positioning reference of the concave and convex sides for clamping and alignment, adjust the gap between the blank and the fixture by shims, and use a three-axis CNC boring and milling machine to process the end faces of A and B to obtain the metal connector.

[0059] 12) The metal connector is scanned to form a three-dimensional actual model and then fitted with the three-dimensional theoretical model to check the dimensions of each part of the workpiece;

[0060] Pre-assembly: All components of the propeller hub are pre-assembled and tightened with bolts, and any interference is checked during the assembly process;

[0061] Static balance test: After assembly with the composite material blade components, a static balance test of the entire blade is carried out.

[0062] The processing method of this invention uses a clamping fixture to ensure a tight fit between the blank and the machining process, facilitating the clamping and alignment of the blank. During rough machining, a reference plane is machined and locating pin holes are bored and milled, serving as a calibration reference for subsequent semi-finishing and finishing, thus improving machining accuracy. This processing method can be widely applied to the manufacture of various connecting parts between propeller hubs and blades, improving product interchangeability by enhancing machining accuracy and enabling mass production.

Claims

1. A method for processing metal connectors for large composite material propellers, characterized in that: The processing method includes the following steps: 1) removing the cap of the casting to obtain a blank; 2) welding positioning base points on the surface of the blank; 3) giving the coordinate values ​​and machining allowance of each positioning base point; 4) rough machining of the blank; 5) aging treatment before semi-finishing and determining the semi-finishing allowance; 6) semi-finishing the blank; 7) aging treatment before finishing and determining the finishing allowance; 8) non-destructive testing; 9) finishing the blank; 10) machining the concave surface and the screw holes and countersunk holes on both sides; and 11) machining the two end faces A and B. The tooling used in processing the metal connectors includes a Type I concave clamping tooling and a Type II convex clamping tooling. The Type I concave clamping tooling includes a clamping base (15), a support frame (16) welded to the clamping base (15), and a Type I blank fitting part (17) welded to the support frame (16). Each end of the Type I blank fitting part (17) is machined with a clamping position (18). The outer surface of the Type I blank fitting part (17) is consistent with the convex surface of the blank. The Type II convex clamping tooling includes a clamping base (15), a support frame (16) welded to the clamping base (15), and a Type II blank fitting part (20) welded to the support frame (16). Each end of the Type II blank fitting part (20) is machined with a clamping position (18). The outer surface of the Type II blank fitting part (20) is consistent with the concave surface of the blank. In step 4), rough machining of the concave surface of the blank: clamp the type I concave surface clamping fixture on the worktable, and place the concave surface of the blank upward and the convex surface downward on the type I blank fitting part (17) of the type I concave surface clamping fixture, clamping the blank at both ends A and B; measure the coordinate values ​​of each positioning base point, and correct the blank according to the coordinate values ​​of each positioning base point after three-dimensional scanning fitting, and adjust the gap between the convex surface of the blank and the type I blank fitting part (17) of the type I concave surface clamping fixture by using shims; then use a three-axis CNC boring and milling machine to rough machine the concave surface and the outline of both sides of the blank according to the three-dimensional model with a 3~4mm allowance on one side; and bore and mill the positioning end plane (19) of the type I concave surface clamping fixture at both ends of the type I blank fitting part (17), and machine the positioning hole of the type I concave surface clamping fixture on the positioning end plane (19) of the type I concave surface clamping fixture; Machining of positioning datum: Weld datum blocks to ends A and B of the blank respectively, machine positioning datum planes on the datum blocks and bore and mill positioning pin holes; Rough machining of the convex surface of the blank: The type II convex surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type II blank fitting part (20) of the type II convex surface clamping fixture with the concave surface facing down and the convex surface facing up. According to the positioning reference plane on the reference block and the positioning end on the type II convex surface clamping fixture, clamp the A and B ends of the blank and align them. Adjust the gap between the concave surface of the blank and the type II blank fitting part (20) of the type II convex surface clamping fixture by using shims. Then, use a three-axis CNC boring and milling machine to rough machine the convex surface of the blank according to the three-dimensional model with a single-sided allowance of 3~4mm. Then, bore and mill the positioning end plane (21) of the type II convex surface clamping fixture at both ends of the type II blank fitting part (20). Machining the positioning hole of the type II convex surface clamping fixture on the positioning end plane (21) of the type II convex surface clamping fixture.

2. The method for processing metal connectors for large composite material propellers according to claim 1, characterized in that: In step 2), a conical or pin-type probe is selected, and the welding material and base point material are the same as the metal connector material; when positioning the welding position, they are evenly distributed on the surface of the blank, and the number of positioning base points is 3 to 6.

3. The method for processing metal connectors for large composite material propellers according to claim 1, characterized in that: In step 3), the blank is scanned to form a three-dimensional model, which is then fitted with the theoretical three-dimensional model of the metal connector. The machining allowance of each part is evenly distributed, and the coordinate values ​​of each positioning base point are given.

4. The method for processing metal connectors for large composite material propellers according to claim 1, characterized in that: In step 6), the concave surface and the outline of the two sides of the blank are semi-finished: the type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part (17) of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. The clamping position clamps the A and B ends of the blank. According to the positioning reference plane on the reference block and the positioning hole of the type I concave surface clamping fixture, the gap between the convex surface of the blank and the type I blank fitting part (17) of the type I concave surface clamping fixture is adjusted by shims; then, the concave surface and the outline of the two sides of the blank are semi-finished by a five-axis CNC boring and milling machine with a single-sided allowance of 0.3~0.5mm according to the three-dimensional model. Semi-finishing of the convex surface of the blank: The type II convex surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type II blank fitting part (20) of the type II convex surface clamping fixture with the concave surface facing down and the convex surface facing up. According to the positioning reference plane on the reference block and the positioning hole of the type II convex surface clamping fixture, clamp the A and B ends of the blank and align them. Adjust the gap between the concave surface of the blank and the type II blank fitting part (20) of the type II convex surface clamping fixture by using shims. Then, use a five-axis CNC boring and milling machine to semi-finish the convex surface of the blank with a single-sided allowance of 0.3~0.5mm according to the three-dimensional model.

5. The method for processing metal connectors for large composite propellers according to claim 4, characterized in that: In step 9), the concave surface and the outline of the two sides of the blank are finished: the type I concave surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type I blank fitting part (17) of the type I concave surface clamping fixture with the concave surface facing up and the convex surface facing down. According to the positioning reference plane on the reference block and the positioning hole of the type I concave surface clamping fixture, the A and B ends of the blank are clamped. The gap between the convex surface of the blank and the type I blank fitting part (17) of the type I concave surface clamping fixture is adjusted by shims. Then, the concave surface and the outline of the two sides of the blank are finished by a five-axis CNC boring and milling machine according to the three-dimensional model. After the machining is completed, the positioning reference on the reference block at both ends A and B is transferred to the concave surface of the blank. Finishing of the convex surface of the blank: The type II convex surface clamping fixture is clamped on the worktable, and the concave surface of the blank is placed on the type II blank fitting part (20) of the type II convex surface clamping fixture with the concave surface facing down and the convex surface facing up. According to the positioning reference plane on the reference block and the positioning hole of the type II convex surface clamping fixture, the A and B ends of the clamping position of the blank are aligned. The gap between the concave surface of the blank and the type II blank fitting part (20) of the type II convex surface clamping fixture is adjusted by shims. Then, the convex surface of the blank is semi-finished by a five-axis CNC boring and milling machine according to the three-dimensional model. After the machining is completed, the positioning reference on the reference blocks at both ends A and B is transferred to the convex surface of the blank.

6. The method for processing metal connectors for large composite material propellers according to claim 5, characterized in that: In step 10), the type I concave clamping fixture is clamped on the worktable, and the blank is placed with the concave side facing up and the convex side facing down on the type I blank fitting part (17) of the type I concave clamping fixture. Based on the positioning reference plane on the reference block and the positioning hole of the type I concave clamping fixture, the center coordinates of each machining screw hole and countersunk hole are given in combination with the three-dimensional model. Then, the screw holes and countersunk holes are machined by a five-axis CNC boring and milling machine.

7. The method for processing metal connectors for large composite propellers according to claim 5, characterized in that: In step 11), the concave and convex surfaces of the blank are clamped and aligned using the positioning reference of the concave and convex surfaces. The gap between the blank and the fixture is adjusted by shims. The end faces of both ends A and B are machined using a three-axis CNC boring and milling machine to obtain the metal connector.

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