Forming die and forming method for composite paddle of unmanned aerial vehicle

Abstract

The invention discloses an unmanned aerial vehicle composite material paddle forming die which comprises an upper die base, a lower die base and a step guide column, and when the upper die base and the lower die base are correspondingly closed, a paddle upper surface cavity of the upper die base and a paddle lower surface cavity of the lower die base form a paddle die cavity. The invention further provides a forming method of the composite paddle of the unmanned aerial vehicle, the middle paddle core is foamed to be manufactured into a preformed part, the main lifting surface part of the paddle and the carbon fiber prepreg cloth are subjected to mold pressing in a direct foaming mode by filling a high-magnification foaming sheet, and one-time thermocuring forming is carried out, so that the composite paddle of the unmanned aerial vehicle is obtained. The carbon fiber layer is arranged on the foaming paddle core, so that the adhesive force between the foaming paddle core and the carbon fiber layer is increased, buckling deformation and layering failure after the paddle is formed are prevented, through orderly transition of layers of all parts of the whole paddle and reasonable layer angle design, the radial stretching performance, the in-plane bending performance and the torsion resistance performance of the paddle are improved, nonlinear flutter failure of the paddle is avoided, and the service life of the paddle is prolonged. Therefore, the aeroelastic stability of the blade is enhanced, and meanwhile, the blade is lighter.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles, and specifically relates to a forming mold and a forming method for a composite material blade of an unmanned aerial vehicle. Background Art

[0002] In recent years, unmanned aerial vehicles have achieved rapid development in various application fields such as aerial photography and entertainment, agricultural and forestry plant protection, inspection and surveying, emergency response, security, and material transportation. Among them, composite material blades are widely used as lift components in the power systems of unmanned aerial vehicles, and the composite material blades need to meet the requirements of high strength, lightweight, and precision of the aerodynamic shape.

[0003] For traditional composite material blades, CNC machining or die preforming of the entire blade core is commonly used, and carbon fiber prepreg is laid on the blade core in a certain laying manner, and then molded by die pressing. In this way, the blade core of the blade undergoes foaming and heat curing, and then is bonded and molded with the carbon fiber prepreg, undergoing secondary heat curing. This method is likely to cause internal stress during die pressing of the formed blade due to the shape deviation of the already cured blade core, resulting in warping and deformation of the blade, affecting the precision of the aerodynamic shape and the aerodynamic efficiency of the blade, and even causing delamination failure, leading to a low yield rate of the blade product. In addition, since the blade uses a carbon fiber prepreg laying method, it also has a great impact on the strength of the blade.

[0004] Therefore, it is necessary to design a reasonable forming method for the composite material blade mold of an unmanned aerial vehicle, so as to meet the requirements of lightweight and precision of the aerodynamic shape of the blade, and at the same time improve the forming yield rate of the composite material blade product. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a forming mold for a composite material blade of an unmanned aerial vehicle, through which the requirements of lightweight and precision of the aerodynamic shape of the composite material blade of the unmanned aerial vehicle can be effectively improved, and the forming yield rate of the composite material blade product can be increased.

[0006] On the one hand, the present invention provides a forming mold for a composite material blade of an unmanned aerial vehicle, including:

[0007] An upper mold base, on which a plurality of blade upper surface cavities are provided;

[0008] A lower mold base, on which blade lower surface cavities with the same number and corresponding positions as the blade upper surface cavities are provided;

[0009] Step guide posts, used for guiding and positioning the corresponding mold closing of the upper mold base and the lower mold base;

[0010] Wherein, when the upper die base and the lower die base are correspondingly closed, the cavity on the upper surface of the blade and the cavity on the lower surface of the blade form a blade mold cavity, so as to form a blade formed part from the foam material group and the composite material carbon fiber yarn sheet group that are filled and laid under set conditions.

[0011] Further, there are four cavities on the upper surface of the blade and four cavities on the lower surface of the blade, and they are longitudinally arranged on the upper die base and the lower die base respectively.

[0012] Further, guide post step holes are provided at the four corners of the upper die base, guide post mounting holes are provided at the four corners of the lower die base, the lower end of the stepped guide post is arranged in the guide post mounting holes, and the upper die base is mutually matched with the upper step of the stepped guide post through the guide post step holes, so as to facilitate the closing of the upper die base and the lower die base.

[0013] Further, a number of bolt through holes are provided on the upper die base, bolt mounting threaded holes with the same number and positions as the bolt through holes are provided on the lower die base, and the upper die base is connected to the lower die base by bolts passing through the bolt through holes and the bolt mounting threaded holes, so that the upper die base and the lower die base are mutually pressed and closed.

[0014] Further, a demoulding keyway for demoulding the upper die base and the lower die base is also provided on the lower die base.

[0015] On the other hand, the present invention also provides a method for forming a composite material blade of an unmanned aerial vehicle, including the following steps:

[0016] Step S1, material preparation: Prepare a foam material group and a composite material carbon fiber yarn sheet group. The foam material group includes a middle section blade core formed by a middle section blade core foaming mold, a high magnification foaming core material for the effective blade section, and a high magnification foaming core material for the blade transition section cut out; the composite material carbon fiber yarn sheet group includes a rectangular yarn sheet for filling the round hole of the middle section blade core, a middle section carbon fiber yarn sheet, a blade transition section carbon fiber yarn sheet, and a whole blade carbon fiber yarn sheet; wherein the middle section carbon fiber yarn sheet includes a large size middle section carbon fiber yarn sheet and a small size middle section carbon fiber yarn sheet, the blade transition section carbon fiber yarn sheet includes a large size blade transition section carbon fiber yarn sheet and a small size blade transition section carbon fiber yarn sheet, and the whole blade carbon fiber yarn sheet includes a large size whole blade carbon fiber yarn sheet and a small size whole blade carbon fiber yarn sheet;

[0017] Step S2, mold preparation: Open the blade forming mold and clean the blade forming mold.

[0018] Step S3, mold preheating: After closing the blade forming mold, place it on a hot press for preheating, heat the surface of the blade forming mold to 55 °C, and apply a demoulding agent on the cavity surface and the inner surface of the blade forming mold.

[0019] Step S4, filling the inner hole of the middle section paddle core: Roll the rectangular yarn sheet into a cylinder and fill it into the round hole of the middle section paddle core, where the rectangular yarn sheet is a 0° / 90° woven yarn sheet;

[0020] Step S5, laying the carbon fiber yarn sheet on the middle section paddle core: Lay a layer of large-sized middle section carbon fiber yarn sheet and align it to wrap around the lower surface of the middle section paddle core, equidistant left and right, ensuring a flat laying. Then lay a layer of small-sized middle section carbon fiber yarn sheet and align it to wrap around the middle area of the paddle core, equidistant left and right, ensuring a flat laying. And the large-sized yarn sheet is 2 - 3 mm wider than the small-sized yarn sheet to facilitate the transitional overlap between the large-sized and small-sized yarn sheets. When laying the second layer, repeat Step S5 to form the preform of the middle section paddle core;

[0021] Step S6, laying the carbon fiber yarn sheet on the mold surface: Lay a layer of large-sized carbon fiber yarn sheet for the whole paddle blade on the cavity of the lower surface of the paddle blade of the lower mold base of the paddle blade. The large-sized carbon fiber yarn sheet for the whole paddle blade extends 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade and 10 mm beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. At the same time, lay a layer of small-sized carbon fiber yarn sheet for the whole paddle blade on the cavity of the upper surface of the paddle blade of the upper mold base of the paddle blade. The small-sized carbon fiber yarn sheet for the whole paddle blade extends 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade and does not extend beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S6;

[0022] Step S7, laying the carbon fiber yarn sheet for the transition section of the paddle blade: Lay a layer of large-sized carbon fiber yarn sheet for the transition section of the paddle blade at the middle position of the large-sized carbon fiber yarn sheet for the whole paddle blade, equidistant left and right. The large-sized carbon fiber yarn sheet for the transition section of the paddle blade extends 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade and 10 mm beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. Lay a layer of small-sized carbon fiber yarn sheet for the transition section of the paddle blade at the middle position of the small-sized carbon fiber yarn sheet for the whole paddle blade, equidistant left and right. The small-sized carbon fiber yarn sheet for the transition section of the paddle blade extends 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade and does not extend beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S7;

[0023] Step S8, laying the foam core material of the paddle blade: Place the preform of the middle section paddle core made in Step S5 at the middle position of the cavity of the lower mold of the paddle blade after laying in Step S6 and Step S7, equidistant left and right. Then place two high magnification foam core materials for the effective paddle blade segments closely against the preform of the middle section paddle core and place them on both sides of the preform of the middle section paddle core. The leading and trailing edges are equidistant from the edge of the cavity of the lower mold of the paddle blade. And place two high magnification foam core materials for the transition section of the paddle blade on the high magnification foam core materials for the effective paddle blade segments and closely against the preform of the middle section paddle core. Similarly, the leading and trailing edges are equidistant from the edge of the cavity of the lower mold of the paddle blade;

[0024] Step S9, forming the paddle blade: Place the paddle blade forming mold on the hot press table for forming, set the forming temperature at 150 °C, and the forming time is about 45 min;

[0025] Step S10, mold opening and product grinding: After the blade forming mold cools down, take out the blade formed part, clean the mold thoroughly, grind and clean the rubber blocks and carbon fiber sandwiched yarns in the mold joint line area of the formed blade. After cleaning, place the blade formed part in the semi-finished product placement area.

[0026] Further, for the large-sized middle-section carbon fiber yarn sheets and small-sized middle-section carbon fiber yarn sheets laid on the middle-section blade core, the laying angle of the first layer is 0° for both, and the laying angle of the second layer is 90° for both.

[0027] Further, in step S6, for the large-sized whole-blade carbon fiber yarn sheets and small-sized whole-blade carbon fiber yarn sheets laid on the mold surface, the laying angle of the first layer is 30° for both; the laying angle of the second layer is 0° for both; the laying angle of the third layer is 90° for both.

[0028] Further, in step S7, for the large-sized blade transition-section carbon fiber yarn sheets and small-sized blade transition-section carbon fiber yarn sheets, the laying angle of the first layer is 45° for both, the laying angle of the second layer is -45° for both, and the laying angle of the third layer is 0° for both.

[0029] Further, in the carbon fiber laying of the blade in steps S5 - S7, the length of the yarn sheet is at the cross-section position of the middle section of the blade, and the total number of laying layers is 8 layers. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45° / 0° / 90° / 0°; the length of the yarn sheet is from the middle section of the blade to the cross-section position of the blade transition section, and the total number of laying layers is 6 layers. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45°; the length of the yarn sheet is from the blade transition section to the cross-section position of the whole blade section, and the total number of laying layers is 3 layers. In the order from outside to inside, the laying angles are 30° / 0° / 90°, and the middle is the blade foam layer.

[0030] Compared with the prior art, the present invention makes the middle-section blade core into a preform by foaming. The main lift surface part of the blade adopts the method of directly foaming with a high-ratio foaming sheet filled, and is molded together with the carbon fiber prepreg by one-time heat curing to increase the adhesion between the foamed blade core and the carbon fiber layer, prevent warping deformation and delamination failure after the blade is formed, so as to not only meet the requirements of the aerodynamic shape precision of the composite blade, but also improve the forming yield rate of the blade; in addition, through the orderly transition of the laying of each part of the whole blade and the reasonable design of the laying angle in the present invention, the radial tension, in-plane bending and anti-torsion performance of the blade are all improved, avoiding non-linear flutter failure of the blade, thereby enhancing the aeroelastic stability of the blade and making the blade lighter in mass. Description of the Drawings

[0031] To more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is the overall explosion diagram of the embodiment of the present invention;

[0033] Figure 2 It is the schematic diagram of the specific setting of the components in the embodiment of the present invention;

[0034] Figure 3 It is the schematic diagram of the foam core group of the paddle in the embodiment of the present invention;

[0035] Figure 4 It is the schematic diagram of the composite material carbon fiber yarn sheet group in the embodiment of the present invention;

[0036] Figure 5 It is the schematic diagram of the laying position of the carbon fiber yarn sheet and foam of the paddle blade in the embodiment of the present invention;

[0037] Figure 6 It is the schematic diagram of the mold clamping of the paddle blade in the embodiment of the present invention;

[0038] Figure 7 It is the schematic diagram of the mold opening of the paddle blade in the embodiment of the present invention;

[0039] Figure 8 It is the schematic diagram of the laying angle design of the carbon fiber yarn sheet of the paddle blade in the embodiment of the present invention;

[0040] Explanation of reference numerals:

[0041] 1. It includes an upper mold base, 11. Guide post step hole, 12. Cavity of the upper surface of the paddle blade, 13. Bolt through hole;

[0042] 2. Lower mold base, 21. Guide post installation hole, 22. Cavity of the lower surface of the paddle blade, 23. Bolt installation threaded hole, 24. Glue flow groove, 25. Demolding keyway;

[0043] 3. Step guide post;

[0044] 4. Foam material group, 41. Middle section paddle core, 42. High magnification foamed core material of the effective paddle blade section, 43. High magnification foamed core material of the paddle blade transition section;

[0045] 5. Composite material carbon fiber yarn sheet group, 51. Rectangular yarn sheet, 52. Middle section carbon fiber yarn sheet, 521. Large-sized middle section carbon fiber yarn sheet, 522. Small-sized middle section carbon fiber yarn sheet, 53. Blade transition section carbon fiber yarn sheet, 531. Large-sized blade transition section carbon fiber yarn sheet, 532. Small-sized blade transition section carbon fiber yarn sheet, 54. Whole blade carbon fiber yarn sheet, 541. Large-sized whole blade carbon fiber yarn sheet, 542. Small-sized whole blade carbon fiber yarn sheet;

[0046] 6. Blade forming part. Detailed implementation manners

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.

[0048] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprise" indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their combinations.

[0049] It should also be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms.

[0050] It should be further understood that the term " / and / " used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0051] Aiming at the problems in the prior art that during the forming process of the composite material blade of an unmanned aerial vehicle, due to the warping and deformation of the blade, the precision of the aerodynamic shape and the aerodynamic efficiency of the blade are affected, and delamination failure occurs, resulting in a low yield rate of the blade product, the embodiment of the present invention provides a forming mold for the composite material blade of an unmanned aerial vehicle.

[0052] Please refer to Figure 1 , Figure 2 As shown, the forming mold of this embodiment includes an upper mold base 1, a lower mold base 2 and a stepped guide post 3. When the upper mold base 1 and the lower mold base 2 are closed correspondingly, they are guided and positioned by the stepped guide post 3.

[0053] Among them, a plurality of upper blade surface cavities 12 are arranged longitudinally on the upper die base 1, and a plurality of bolt through holes 13 are arranged longitudinally.

[0054] On the lower die base 2, a plurality of lower blade surface cavities 22 with the same number and corresponding positions as the upper blade surface cavities 12 are arranged longitudinally, and bolt installation threaded holes 23 with the same number and corresponding positions as the bolt through holes 13 are arranged. The upper die base 1 is connected to the lower die base 2 by bolts passing through the bolt through holes 13 and the bolt installation threaded holes 23, so that the upper die base 1 and the lower die base 2 are pressed against each other for clamping.

[0055] The lower die base 2 is further provided with a glue flow groove 24 and a demolding key groove 25. There are four glue flow grooves 24, which are arranged around the edge of the blade and are used for extruding excess resin glue during the molding of the blade, so that the quality distribution of the blade molding is more uniform, avoiding problems such as delamination of the carbon fiber cloth of the blade caused by uneven resin distribution, and further avoiding the failure of blade molding. The demolding key groove 25 is used to realize the demolding of the upper die base 1 and the lower die base 2.

[0056] In this embodiment, the number of the upper surface cavities 12 and the lower blade surface cavities 22 is four each, and four blades can be molded in one mold. The number of the bolt through holes 13 and the bolt installation threaded holes 23 is nine each.

[0057] One guide post step hole 11 is respectively arranged at the four corners of the upper die base 1, and guide post installation holes 21 corresponding to the guide post step holes 11 are arranged at the four corners of the lower die base 2. The lower end of the stepped guide post 3 is arranged in the guide post installation hole 21, and the upper die base 1 is mutually matched with the upper step of the upper end of the stepped guide post 3 through the guide post step hole 11, so as to facilitate the clamping of the upper die base 1 and the lower die base 2.

[0058] When the upper die base 1 and the lower die base 2 are correspondingly clamped, the upper blade surface cavity 12 and the lower blade surface cavity 22 form a blade mold cavity to form a blade formed part 6 from the foam material group 4 and the composite material carbon fiber yarn sheet group 5 filled and laid under set conditions.

[0059] As Figure 3 shown, in this embodiment, the foam material group 4 includes a middle blade core 41, a high magnification foaming core material 42 for the effective blade section, and a high magnification foaming core material 43 for the blade transition section.

[0060] As Figure 4 shown, in this embodiment, the composite material carbon fiber yarn sheet group 5 includes a rectangular yarn sheet 51, a middle section carbon fiber yarn sheet 52, a carbon fiber yarn sheet 53 for the blade transition section, and a carbon fiber yarn sheet 54 for the whole blade.

[0061] Among them, the middle-section carbon fiber yarn sheets 52 include large-sized middle-section carbon fiber yarn sheets 521 and small-sized middle-section carbon fiber yarn sheets 522; the blade transition-section carbon fiber yarn sheets 53 include large-sized blade transition-section carbon fiber yarn sheets 531 and small-sized blade transition-section carbon fiber yarn sheets 532; the whole-blade carbon fiber yarn sheets 54 include large-sized whole-blade carbon fiber yarn sheets 541 and small-sized whole-blade carbon fiber yarn sheets 542.

[0062] Another embodiment of the present invention provides a method for forming a composite material blade of a drone, including the following steps:

[0063] Step S1, material preparation: Prepare a number of foam material groups 4 and composite material carbon fiber yarn sheet groups 5, which are respectively a number of middle-section blade cores 41 formed by a middle-section blade core foaming mold, a number of high-ratio foamed core materials 42 for the effective blade section, a number of high-ratio foamed core materials 43 for cutting out the blade transition section, a number of rectangular yarn sheets 51 for filling the round holes of the middle-section blade core 41, a number of middle-section carbon fiber yarn sheets 52, a number of blade transition-section carbon fiber yarn sheets 53, and a number of whole-blade carbon fiber yarn sheets 54. Among them, the middle-section carbon fiber yarn sheets 52 include two types, namely large-sized middle-section carbon fiber yarn sheets 521 and small-sized middle-section carbon fiber yarn sheets 522, the blade transition-section carbon fiber yarn sheets 53 include two types, namely large-sized blade transition-section carbon fiber yarn sheets 531 and small-sized blade transition-section carbon fiber yarn sheets 532, and the whole-blade carbon fiber yarn sheets 54 include large-sized whole-blade carbon fiber yarn sheets 541 and small-sized whole-blade carbon fiber yarn sheets 542 (see Figure 3 and Figure 4 );

[0064] Step S2, mold preparation: Take out the composite material blade forming mold from the mold rack, open the blade forming mold, and clean the blade forming mold with an air gun. When there is a lot of resin residue on the blade forming mold and it cannot be cleaned thoroughly, use a mold cleaner to clean it (see Figure 1 );

[0065] Step S3, mold preheating: After closing the blade forming mold, place it on the hot press table for preheating. Heat the surface of the blade forming mold to about 55 °C, and apply a release agent to the cavity surface of the blade forming mold and other inner surfaces of the blade forming mold with a brush (see Figure 6 );

[0066] Step S4, filling the inner hole of the middle-section blade core: Roll the rectangular yarn sheet 51 into a cylinder and fill it into the round hole of the middle-section blade core 41 (see Figure 5 );

[0067] Step S5, laying the carbon fiber yarn sheets for the middle section of the paddle core: Wrap one layer of large-sized carbon fiber yarn sheets 521 for the middle section around the lower surface of the middle section of the paddle core 41 in alignment, equidistant left and right, ensuring a flat laying. Then wrap one layer of small-sized carbon fiber yarn sheets 522 for the middle section around the middle area of the paddle core in alignment, equidistant left and right, ensuring a flat laying. And the large-sized sheets are 2 - 3 mm wider than the small-sized sheets to facilitate the transitional overlap between the large-sized and small-sized sheets. When laying the second layer, repeat Step S5 to form a preform for the middle section of the paddle core (see Figure 5 );

[0068] Step S6, laying the carbon fiber yarn sheets on the mold surface: Lay one layer of large-sized carbon fiber yarn sheets 541 for the entire paddle blade on the cavity 22 of the lower surface of the paddle blade of the lower mold base 2 of the paddle blade. The large-sized carbon fiber yarn sheets 541 for the entire paddle blade extend about 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade, and extend about 10 mm beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. At the same time, lay one layer of small-sized carbon fiber yarn sheets 542 for the entire paddle blade on the cavity 12 of the upper surface of the paddle blade of the upper mold base 1 of the paddle blade. The small-sized carbon fiber yarn sheets 542 for the entire paddle blade extend about 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade, and do not extend beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S6 (see Figure 5 );

[0069] Step S7, laying the carbon fiber yarn sheets for the transition section of the paddle blade: Lay one layer of large-sized carbon fiber yarn sheets 531 for the transition section of the paddle blade at the middle position of the large-sized carbon fiber yarn sheets 541 for the entire paddle blade, equidistant left and right. The large-sized carbon fiber yarn sheets 531 for the transition section of the paddle blade extend about 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade, and extend about 10 mm beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. Lay one layer of small-sized carbon fiber yarn sheets 532 for the transition section of the paddle blade at the middle position of the small-sized carbon fiber yarn sheets 542 for the entire paddle blade, equidistant left and right. The small-sized carbon fiber yarn sheets 532 for the transition section of the paddle blade extend about 2 mm beyond the mold cavity at the trailing edge and tip of the paddle blade, and do not extend beyond the mold cavity at the leading edge of the paddle blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S7 (see Figure 5 );

[0070] Step S8, laying the foam core material for the paddle blade: Place the preform for the middle section of the paddle core made in Step S5 at the middle position of the cavity of the lower mold of the paddle blade after the laying in Step S6 and Step S7, equidistant left and right. Then place two pieces of high magnification foam core materials 42 for the effective paddle blade section closely against the preform for the middle section of the paddle core and place them on both sides of the preform for the middle section of the paddle core. The front and rear edges are equidistant from the edge of the cavity of the lower mold of the paddle blade. And place two pieces of high magnification foam core materials 43 for the transition section of the paddle blade on the high magnification foam core materials 42 for the effective paddle blade section and closely against the preform for the middle section of the paddle core. Similarly, the front and rear edges are equidistant from the edge of the cavity of the lower mold of the paddle blade (see Figure 5 );

[0071] Step S9, Blade Molding: Place the blade molding die on the hot press for molding. Set the molding temperature at 150 °C and the molding time at about 45 min (see Figure 6 ).

[0072] Step S10, Mold Opening and Product Grinding: After the blade molding die cools down, take out the blade molding part 6, clean the die, and grind and clean the rubber blocks and carbon fiber sandwich yarns in the mold joint line area of the molded blade. After cleaning, place the blade molding part 6 in the semi-finished product placement area (see Figure 7 ).

[0073] In this embodiment, refer to Figure 5 . By making the middle blade core preform through step S5, and laying the high magnification foamed core material 42 of the effective blade section and the high magnification foamed core material 43 of the blade transition section through step S8, when the blade is molded in step S9, the high magnification foamed core material 42 of the effective blade section and the high magnification foamed core material 43 of the blade transition section are foamed synchronously, so that the high magnification foamed core material can be uniformly and effectively filled into the cavity after the carbon fiber laying in steps S6 - S7. This can not only enhance the adhesion between the blade core and the carbon fiber layer, but also reduce the delamination failure at the sharp position of the trailing edge of the molded blade, improve the yield of the molded blade. At the same time, because the foamed core material is evenly distributed in the cavity, that is, the mass is relatively evenly distributed, it is more beneficial to the subsequent dynamic imbalance adjustment.

[0074] In this embodiment, in step S4, the rectangular yarn sheet 51 is a 0° / 90° braided yarn sheet, which is filled into the round holes of the middle blade core 41 as the hardened area for the blade clamp and the motor installation position, and is used for milling the blade installation holes.

[0075] In this embodiment, refer to Figure 8 . In step S5, for the large-sized middle section carbon fiber yarn sheet 521 and the small-sized middle section carbon fiber yarn sheet 522 laid on the middle blade core carbon fiber yarn sheet, the first layer laying angle is 0° for both, and the second layer laying angle is 90° for both.

[0076] In this embodiment, refer to Figure 8 . In step S6, for the large-sized whole blade carbon fiber yarn sheet 541 and the small-sized whole blade carbon fiber yarn sheet 542 laid on the mold surface carbon fiber yarn sheet, the first layer laying angle is 30° for both. The 30° laying can better fit the curved surface, reduce bending wrinkles, and can also provide a certain torsional resistance for the blade. The second layer laying angle is 0° for both, which is used to maintain the radial tensile and in-plane bending resistance of the whole blade. The third layer laying angle is 90° for both, which is used to enhance the lateral stiffness of the blade.

[0077] In this embodiment, refer to Figure 8, in step S7, for the large blade transition section carbon fiber yarn sheet 531 and the small blade transition section carbon fiber yarn sheet 532, the laying angle of the first layer is 45° and the laying angle of the second layer is -45° for improving the torsional resistance of the blade transition section, and the laying angle of the third layer is 0° for maintaining the radial tensile and in-plane bending resistance of the blade transition section.

[0078] In this embodiment, referring to Figure 8 , in the carbon fiber laying of the blade in steps S5 - S7, the length of the yarn sheet is at the profile position of the middle section of the blade, and the total number of laying layers is 8. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45° / 0° / 90° / 0°. The length of the yarn sheet is from the middle section of the blade to the profile position of the blade transition section, and the total number of laying layers is 6. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45°. The length of the yarn sheet is from the blade transition section to the profile position of the whole blade section, and the total number of laying layers is 3. In the order from outside to inside, the laying angles are 30° / 0° / 90°. The middle is the blade foam layer. The orderly transition of the laying in each part of the whole blade and the reasonable design of the laying angle enable the blade to improve both the radial tensile and in-plane bending resistance and the torsional resistance of the blade, that is, to improve the strength of the blade and make the blade lighter.

[0079] In summary, through the orderly transition of the laying in each part of the whole blade and the reasonable design of the laying angle, the present invention improves the radial tensile, in-plane bending and torsional resistance of the blade, avoids the non-linear flutter failure of the blade, thereby enhancing the aeroelastic stability of the blade, and at the same time making the blade lighter in mass.

[0080] The specific embodiments of the invention have been described in detail above, but they are only examples, and the invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the invention. Therefore, all equal transformations, modifications and improvements made without departing from the spirit and principle of the invention should be covered within the scope of the invention.

Claims

1. A forming mold for a composite blade of a drone, characterized in that Comprising: An upper die base (1) provided with a plurality of upper blade surface cavities (12) thereon; A lower die base (2) provided with lower blade surface cavities (22) having the same number and corresponding positions as the upper blade surface cavities (12); Step guide posts (3) for guiding and positioning the corresponding closing of the upper die base (1) and the lower die base (2); Wherein, when the upper die base (1) and the lower die base (2) are correspondingly closed, the upper blade surface cavity (12) and the lower blade surface cavity (22) form a blade mold cavity to form a blade formed part (6) from a foam material group (4) and a composite material carbon fiber yarn sheet group (5) filled and laid under set conditions.

2. The molding die according to claim 1, wherein Both the upper blade surface cavity (12) and the lower blade surface cavity (22) are four in number and are longitudinally arranged on the upper die base (1) and the lower die base (2) respectively.

3. The molding die according to claim 1, wherein Guide post step holes (11) are provided at the four corners of the upper die base (1), guide post mounting holes (21) are provided at the four corners of the lower die base (2), the lower ends of the step guide posts (3) are arranged in the guide post mounting holes (21), and the upper die base (1) is mutually matched with the upper steps of the step guide posts (3) through the guide post step holes (11) to facilitate the closing of the upper die base (1) and the lower die base (2).

4. The molding die according to claim 3, characterized in that, A plurality of bolt through holes (13) are provided on the upper die base (1), bolt mounting threaded holes (23) having the same number and positions as the bolt through holes (13) are provided on the lower die base (2), and the upper die base (1) is connected to the lower die base (2) by bolts passing through the bolt through holes (13) and the bolt mounting threaded holes (23) to press the upper die base (1) and the lower die base (2) tightly for closing.

5. The molding die according to claim 4, wherein, A demoulding keyway (25) for demoulding the upper die base (1) and the lower die base (2) is further provided on the lower die base (2).

6. A forming method for a composite blade of an unmanned aerial vehicle, characterized in that, Including the following steps: Step S1, material preparation: Prepare a foam material group (4) and a composite material carbon fiber yarn sheet group (5). The foam material group (4) includes a middle blade core (41) formed by a middle blade core foaming mold, an effective blade segment high magnification foaming core (42), and a cut-out blade transition segment high magnification foaming core (43); the composite material carbon fiber yarn sheet group (5) includes a rectangular yarn sheet (51) for filling the round holes of the middle blade core (41), a middle carbon fiber yarn sheet (52), a blade transition segment carbon fiber yarn sheet (53), and a whole blade carbon fiber yarn sheet (54); wherein the middle carbon fiber yarn sheet (52) includes a large-sized middle carbon fiber yarn sheet (521) and a small-sized middle carbon fiber yarn sheet (522), the blade transition segment carbon fiber yarn sheet (53) includes a large-sized blade transition segment carbon fiber yarn sheet (531) and a small-sized blade transition segment carbon fiber yarn sheet (532), and the whole blade carbon fiber yarn sheet (54) includes a large-sized whole blade carbon fiber yarn sheet (541) and a small-sized whole blade carbon fiber yarn sheet (532); Step S2, mold preparation: Open the blade forming mold and clean the blade forming mold. Step S3, Mold Preheating: After closing the blade forming mold, place it on the hot press table for preheating. Heat the surface of the blade forming mold to 55°C, and apply a release agent to the cavity surface and inner surface of the blade forming mold; Step S4, Filling the Inner Hole of the Middle Blade Core: Roll the rectangular yarn sheet (51) into a cylindrical shape and fill it into the round hole of the middle blade core (41), where the rectangular yarn sheet (51) is a 0° / 90° woven yarn sheet; Step S5, Laying the Carbon Fiber Yarn Sheet on the Middle Blade Core: Lay a layer of large-sized middle-section carbon fiber yarn sheet (521) and align it to wrap around the lower surface of the middle blade core (41), equidistant left and right, ensuring a flat laying. Then lay a layer of small-sized middle-section carbon fiber yarn sheet (522) and align it to wrap around the middle area of the blade core, equidistant left and right, ensuring a flat laying. And the large-sized yarn sheets are 2 - 3 mm wider than the small-sized yarn sheets to facilitate the transition and overlap between the large-sized and small-sized yarn sheets. When laying the second layer, repeat Step S5 to form a preform of the middle blade core; Step S6, Laying the Carbon Fiber Yarn Sheet on the Mold Surface: Lay a layer of large-sized whole-blade carbon fiber yarn sheet (541) into the blade lower surface cavity (22) of the blade lower mold base (2). The large-sized whole-blade carbon fiber yarn sheet (541) extends 2 mm beyond the mold cavity at the trailing edge and tip of the blade, and 10 mm beyond the mold cavity at the leading edge of the blade, and ensure a flat laying without air bubbles. At the same time, lay a layer of small-sized whole-blade carbon fiber yarn sheet (542) into the blade upper surface cavity (12) of the blade upper mold base (1). The small-sized whole-blade carbon fiber yarn sheet (542) extends 2 mm beyond the mold cavity at the trailing edge and tip of the blade, and does not extend beyond the mold cavity at the leading edge of the blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S6; Step S7, Laying the Carbon Fiber Yarn Sheet in the Blade Transition Section: Lay a layer of large-sized blade transition section carbon fiber yarn sheet (531) at the middle position of the large-sized whole-blade carbon fiber yarn sheet (541), equidistant left and right. The large-sized blade transition section carbon fiber yarn sheet (531) extends 2 mm beyond the mold cavity at the trailing edge and tip of the blade, and 10 mm beyond the mold cavity at the leading edge of the blade, and ensure a flat laying without air bubbles. Lay a layer of small-sized blade transition section carbon fiber yarn sheet (532) at the middle position of the small-sized whole-blade carbon fiber yarn sheet (542), equidistant left and right. The small-sized blade transition section carbon fiber yarn sheet (532) extends 2 mm beyond the mold cavity at the trailing edge and tip of the blade, and does not extend beyond the mold cavity at the leading edge of the blade, and ensure a flat laying without air bubbles. When laying the second and third layers, repeat Step S7; Step S8, Laying the Blade Foaming Core Material: Place the preform of the middle blade core made in Step S5 at the middle position of the blade lower mold cavity after being laid in Step S6 and Step S7, equidistant left and right. Then place two high-magnification foaming core materials (42) of the effective blade segments closely against the preform of the middle blade core and place them on both sides of the preform of the middle blade core, with the front and rear edges equidistant from the edge of the blade lower mold cavity. And place two high-magnification foaming core materials (43) of the blade transition sections on the high-magnification foaming core materials (42) of the effective blade segments and closely against the preform of the middle blade core. Similarly, the front and rear edges are equidistant from the edge of the blade lower mold cavity; Step S9, blade forming: Place the blade forming mold on the hot press for forming, set the forming temperature at 150°C, and the forming time at about 45 minutes. Step S10, mold opening and product grinding: After the blade forming mold cools down, take out the blade forming part (6), clean the mold, grind and clean the glue blocks and carbon fiber sandwich yarns in the mold joint line area of the formed blade. After cleaning, place the blade forming part (6) in the semi-finished product storage area.

7. The forming method according to claim 6, characterized in that In step S5, for the large-sized middle-section carbon fiber yarn sheets (521) and small-sized middle-section carbon fiber yarn sheets (522) laid on the middle-section blade core carbon fiber yarn sheets, the laying angle of the first layer is 0°, and the laying angle of the second layer is 90°.

8. The molding method according to claim 6, characterized in that, In step S6, for the large-sized whole-blade carbon fiber yarn sheets (541) and small-sized whole-blade carbon fiber yarn sheets (542) laid on the mold surface carbon fiber yarn sheets, the laying angle of the first layer is 30°; the laying angle of the second layer is 0°; the laying angle of the third layer is 90°.

9. The molding method according to claim 6, characterized in that, In step S7, for the large-sized blade transition section carbon fiber yarn sheets (531) and small-sized blade transition section carbon fiber yarn sheets (532), the laying angle of the first layer is 45°, the laying angle of the second layer is -45°, and the laying angle of the third layer is 0°.

10. The forming method according to claim 6, characterized in that, In the carbon fiber laying of the blade in steps S5 - S7, the length of the yarn sheet is at the cross-section position of the middle section of the blade. The total number of laying layers is 8. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45° / 0° / 90° / 0°; the length of the yarn sheet is from the middle section of the blade to the cross-section position of the blade transition section. The total number of laying layers is 6. In the order from outside to inside, the laying angles are 30° / 0° / 90° / 45° / -45°; the length of the yarn sheet is from the blade transition section to the cross-section position of the whole blade section. The total number of laying layers is 3. In the order from outside to inside, the laying angles are 30° / 0° / 90°. The middle is the blade foam layer.

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