Paddle

Abstract

The utility model belongs to the field of thermosetting composite materials, and particularly discloses a paddle. According to the paddle, the light foamed foam sheet is adopted as the sandwich sheet in the sandwich structure, the foam sheet and the reinforcing layer form the sandwich structure, the mounting capacity of the paddle is improved, further, all the components contain resin components, the materials are similar, the components can be integrally molded through integral mold pressing after being heated and melted, and the production cost is reduced. The size of the profiling structure obtained through mold pressing can be controlled through a mold, the profiling structure is accurate in size, the profiling cambered surface is smooth, attaching to the appearance of the blade is facilitated, and therefore in the process aspect, compared with a CNC machining scheme, the efficiency is higher, the cost is lower, batch production can be achieved, secondary machining is avoided, the efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] The utility model belongs to the field of thermosetting composite materials, and in particular relates to a blade. Background Art

[0002] Fiber-reinforced thermosetting composite materials have been widely used in many fields such as automobile industry, aerospace, military industry, electronics, etc. due to their advantages of light weight, high specific strength, high specific modulus, good toughness, and good processability. In the field of aerospace, the application of carbon fiber or glass fiber in the field of drones is gradually increasing, and carbon fiber or glass fiber blades are an important direction for the selection of drone blades.

[0003] Fiber blades have the following advantages: (1) The use of fiber materials can minimize the weight of the product and obtain the best material properties; (2) The fibers can be freely designed. By combining fibers of different grades (high strength, high modulus), different material properties can be achieved to meet product requirements; (3) The use of fiber materials can improve the fatigue resistance of the blades. However, the industry needs to use all fiber composites to form blades in order to meet customers' requirements for corresponding performance. However, the material layer design of this solution is relatively simple. However, the weight of the all-carbon fiber or all-glass fiber structure is still relatively high, which has a negative impact on the endurance of flying equipment such as drones. In addition, the bearing capacity of the entire blade is poor, the mounting weight is low, and its application is limited. Summary of the invention

[0004] In view of the problem of poor blade mounting capacity in the above-mentioned prior art, the utility model provides a blade.

[0005] To achieve the above purpose, the following technical solutions are specifically included:

[0006] The utility model provides a blade, comprising at least two blade surface layers, at least two reinforcement layers and a sandwich structure;

[0007] The sandwich structure and the reinforcement layer are arranged between the blade surface layers;

[0008] At least two reinforcement layers are stacked in sequence along the thickness direction, and the sandwich structure is arranged between any two adjacent reinforcement layers;

[0009] The sandwich structure comprises at least three layers of sandwich sheets, which are stacked in sequence in the thickness direction of the sandwich structure, a fiber reinforcement layer is arranged between any two adjacent layers of sandwich sheets, and the sandwich sheets comprise foam sheets;

[0010] The blade has a through hole, and the through hole passes through the blade surface layer, the reinforcement layer and the sandwich structure.

[0011] The utility model can obviously improve the load capacity of the blade by using the sandwich structure formed by laminating the foam sheet and the fiber reinforcement layer.

[0012] In one embodiment, the thickness of the foam sheet is 1.5-4.5 mm, the material of the foam sheet includes at least one of PET, PMI, PVC, PU, ​​EVA, and EPDM, and the bulk density of the foam sheet is 40-150 kg / m 3 , the compression ratio of the foam sheet is 10%-50%.

[0013] In one embodiment, the fiber reinforcement layer is made by compression molding of fiber prepreg.

[0014] In one embodiment, the fiber prepreg includes at least one of carbon fiber prepreg and glass fiber prepreg.

[0015] In one embodiment, the carbon fiber prepreg comprises at least one of a carbon fiber prepreg and a carbon fiber woven prepreg impregnated with a carbon fiber felt.

[0016] In one embodiment, the glass fiber prepreg includes at least one of glass fiber prepreg, glass fiber woven prepreg, and impregnated glass fiber mat.

[0017] In one embodiment, in the fiber prepreg, the fiber weight is 50-200 g, and the resin content accounts for 27-45% of the mass of the fiber prepreg.

[0018] In one embodiment, the fiber reinforced layer has a thickness of 0.05-0.25 mm.

[0019] In one embodiment, the glass fiber prepreg includes UD glass fiber prepreg; the carbon fiber prepreg includes UD carbon fiber prepreg; the carbon fiber woven prepreg includes 3K carbon fiber woven prepreg; the glass fiber woven prepreg includes 3K glass fiber woven prepreg.

[0020] In one embodiment, the blade surface layer, reinforcement layer, and sandwich structure are all streamlined structures that are narrow at both ends and wide in the middle, such as the minimum width at both ends is 40-150mm, and the maximum width in the middle is 200-600mm; the center axis of the blade is a circle passing through the through hole and parallel to the length direction of the blade, the upper part of the center axis is the upper side of the blade, and the lower part of the center axis is the lower side of the blade, and the upper side is wide and the lower side is narrow, the upper side is thin and the lower side is thick, that is, the width of the upper side is greater than the width of the lower side, and the thickness of the upper side is less than the thickness of the lower side. The leftmost end of the leading edge of the blade is the blade root, and the rightmost end of the trailing edge of the blade is the blade tail. The plane thickness of the sandwich structure inside the blade root position is greater than 9mm, preferably, 9-15mm, which is an equal thickness area, and the outer diameter of the sandwich structure at the blade root position differs from the outer diameter of the entire blade by 2-3.5mm.

[0021] In one embodiment, the blade has a length of 400-1500 mm and a width of 200-600 mm.

[0022] In one embodiment, the blade surface layer has a length of 400-1500 mm and a width of 200-600 mm.

[0023] In one embodiment, the length and width of the sandwich structure, the reinforcement layer, and the blade surface layer increase sequentially.

[0024] In one embodiment, the width of the lower side of the sandwich structure is 4-8 mm smaller than the width of the blade surface layer, and the width of the upper side of the sandwich structure is 10-15 mm smaller than the width of the blade surface layer.

[0025] In one embodiment, the reinforcing rib has a width of 5-10 mm and a thickness of 1-10 mm.

[0026] In one embodiment, the reinforcing ribs are made by compression molding of carbon fiber prepregs. Preferably, the carbon fiber prepregs are stacked and laid in a manner of 0°, ±20°+0° or ±45°+0°, and the thickness of each layer of carbon fiber prepreg is 0.2-0.3 mm.

[0027] In one embodiment, the sandwich sheet further includes a fiber reinforcement, the through hole penetrates the fiber reinforcement, and the fiber reinforcement layer is made by compression molding of fiber prepreg cloth; the fiber reinforcement is snap-fitted and spliced ​​with the foam sheet, or the fiber reinforcement is stacked and combined with the foam sheet to form a reinforcement.

[0028] The sandwich sheet can be just a foam sheet, or it can be a structure composed of fiber reinforcement and foam sheet. Adding fiber reinforcement on the basis of foam sheet can increase the weight capacity of the propeller root and improve the center of gravity of the blade, which is more conducive to blade mounting and flight stability.

[0029] In one embodiment, the distance between the central axis of the through hole and the snap-fitting portion is 30-120 mm. Preferably, the distance between the central axis of the through hole and the snap-fitting portion is 30-50 mm or 80-120 mm.

[0030] In one embodiment, in the snap-fitting assembly of the fiber reinforcement and the foam sheet, one component is provided with a groove and the other component is provided with a protrusion, and the fiber reinforcement and the foam sheet are snap-fitted via the groove and the protrusion.

[0031] In one embodiment, the number of the protrusions or grooves is ≥1.

[0032] In one embodiment, the groove and the protrusion are connected in a right angle form or in a chamfered form of R3-5mm.

[0033] In one embodiment, the length of the card slot is 15-20 mm, and the width is 10-15 mm.

[0034] In one embodiment, the length of the fiber reinforcement is 50-300 mm.

[0035] In one embodiment, the thickness of the fiber reinforcement is 3-15 mm; the fiber reinforcement is made by compression molding of carbon fiber prepreg, preferably, the carbon fiber prepreg is stacked and laid in a 0° / 90° manner, and the thickness of each layer of carbon fiber prepreg is 0.15-0.3 mm.

[0036] In one embodiment, at least one layer of sandwich sheet is provided with a receiving groove, and reinforcing ribs are provided in the receiving groove.

[0037] On the basis of the fiber reinforcement added in the sandwich structure, adding reinforcing ribs can further increase the weight capacity of the propeller root and improve the center of gravity of the blade, which is more conducive to blade mounting and flight stability.

[0038] In one embodiment, the number of the reinforcing ribs is not less than two and they are arranged at equal intervals, and the reinforcing ribs may extend along the length direction or the width direction of the blade.

[0039] In one embodiment, the reinforcing rib is along the length direction of the blade, the starting position of the reinforcing rib is the same as the starting position of the clamping point, and the ending position is 50-300mm away from the tail end of the sandwich sheet away from the through hole along the length direction, preferably, 50-150mm or 200-300mm.

[0040] In one embodiment, the length of the reinforcing rib is 0.5-0.8 times the length of the blade.

[0041] In one embodiment, the lengths of at least three layers of sandwich sheets increase or decrease successively in the thickness direction of the sandwich structure; the length of the sandwich structure is 15-20 mm smaller than the length of the blade surface layer, and the width of the sandwich structure is 1-8 mm smaller than the width of the blade surface layer.

[0042] In one embodiment, the blade surface layer includes an upper blade surface layer and a lower blade surface layer, and the blade surface layer is made by compression molding of fiber prepreg; the laying method of the fiber prepreg is ±20+0°, ±45+0° or 0°+90°+0°.

[0043] In one embodiment, the number of the reinforcement layers is three, specifically an upper reinforcement layer, an intermediate reinforcement layer, and a lower reinforcement layer, wherein the upper reinforcement layer is arranged on the inner surface of the upper blade surface layer; the lower reinforcement layer is arranged on the inner surface of the lower blade surface layer; the intermediate reinforcement layer is adjacent to the upper reinforcement layer, or the intermediate reinforcement layer is adjacent to the lower reinforcement layer.

[0044] In one embodiment, the width of the reinforcement layer is equidistantly smaller than the width of the blade surface layer by 1-3 mm, and the length of the reinforcement layer is 1-3 mm smaller than the length of the blade surface layer.

[0045] In one embodiment, the reinforcement layer is made by compression molding of fiber prepreg; the plying method of the fiber prepreg is ±20+0°, ±45+0° or 0°+90°+0°, and the thickness of the reinforcement layer is 0.15-0.6mm.

[0046] In one embodiment, the blade further includes an appropriate amount of a padding layer to fill the thickness of the blade, increase the fiber content of the blade root portion, and increase the bearing capacity of the blade root portion.

[0047] In one embodiment, the cushion layer is disposed between the reinforcement layer and the sandwich structure, the shape and width of the cushion layer are the same as those of the reinforcement layer, and the length of the cushion layer is 1 / 3 to 2 / 3 of that of the reinforcement layer.

[0048] In one embodiment, the through hole is cylindrical, and the diameter of the through hole is 15-22 mm.

[0049] Compared with the prior art, the utility model has the following beneficial effects:

[0050] The utility model adopts a lightweight foamed foam sheet as a sandwich sheet in the sandwich structure. The foam sheet and the reinforcement layer form a sandwich structure to improve the mounting capacity of the blade. Furthermore, each component contains a resin component and has similar materials. The components can be heated and melted and then molded as a whole, i.e., integrally formed to produce a complete blade profiling structure. The size of the molded profiling structure can be controlled by the mold, and the size is accurate. The profiling arc surface is smooth, which is more beneficial to the appearance of the blade. Therefore, the process is more efficient and the cost is lower than that of the CNC processing solution. It can also be mass-produced, avoiding secondary processing, improving efficiency and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the blade component structure, wherein 1-upper blade surface layer A, 2-upper blade surface layer B, 3-upper reinforcement layer, 4-upper blade pad thick layer, 5-sandwich structure, 6-lower blade pad thick layer, 7-lower reinforcement layer, 8-lower blade surface layer B, 9-lower blade surface layer A, 10-through hole.

[0052] Figure 2 It is a cross-sectional view of the blade along the width direction, area A is the leading edge of the blade, the blade root is located at the left end of area A, area B is the trailing edge of the blade, 10-through hole, 5-sandwich structure.

[0053] Figure 3It is a schematic structural diagram of the sandwich structure 5-1 of Example 1, wherein 511 is a first foam sheet, 512 is a first fiber reinforced layer, 513 is a second foam sheet, 514 is a second fiber reinforced layer, and 515 is a third foam sheet.

[0054] Figure 4 It is a structural schematic diagram of the sandwich structure 5-2 of Example 2, wherein 521-first foam sheet, 522-first fiber reinforced layer, 523-second foam sheet, 524-second fiber reinforced layer, 525-third foam sheet, 526-first fiber reinforcement, 527-second fiber reinforcement, 528-third fiber reinforcement.

[0055] Figure 5 A schematic diagram of a card slot structure of Example 2.

[0056] Figure 6 It is a structural schematic diagram of the sandwich structure 5-3 of Example 3, wherein 531-first foam sheet, 532-first fiber reinforced layer, 533-second foam sheet, 534-second fiber reinforced layer, 535-third foam sheet, 536-first fiber reinforcement, 537-second fiber reinforcement, 538-third fiber reinforcement.

[0057] Figure 7 Schematic diagram of two card slot structures in Example 3.

[0058] Figure 8 It is a structural schematic diagram of the sandwich structure 5-4 of Example 4, wherein 541-first foam sheet, 542-reinforcement rib receiving groove, 543-first fiber reinforcement layer, 544-second foam sheet, 545-second fiber reinforcement layer, 546-third foam sheet, 547-first fiber reinforcement member, 548-second fiber reinforcement member, 549-third fiber reinforcement member, and the dotted line part in the figure is the position of the receiving groove. DETAILED DESCRIPTION

[0059] In order to better illustrate the purpose, technical solution and advantages of the utility model, the utility model will be further described below through specific examples. The test methods used in the examples and / or comparative examples are conventional methods unless otherwise specified; the materials, reagents, etc. used can be obtained from commercial channels unless otherwise specified.

[0060] In the description of the present utility model, it is necessary to understand that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second" and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more. In the ply structure, 0° is parallel to the length direction, and 90° is parallel to the width direction.

[0061] Example 1

[0062] The layers of the sandwich structure of this embodiment are shown in the attached Figure 3 As shown, the first, second and third sandwich sheets in the sandwich structure are the first foam sheet 511, the second foam sheet 513 and the third foam sheet 515 respectively. The three layers of foam sheets are all lightweight thin sheets, each sheet is 3.5 mm thick, and the material is PET foam material (model: ZK52). The length of the first foam sheet 511 is 643 mm, the length of the second foam sheet is 2 / 3 of the length of the first foam sheet, and the length of the third foam sheet is 1 / 3 of the length of the first foam sheet. The first fiber reinforced layer 512 and the second fiber reinforced layer 514 are both made of 0.1 mm thick glass fiber woven cloth, wherein the resin content of 100 grams of glass fiber woven cloth is 33%, and the glass fiber woven cloth is 67%. The shape, length and width of the first fiber reinforced layer 512 and the second fiber reinforced layer 514 are the same as those of the second foam sheet 511 and the third foam sheet 513 respectively.

[0063] The preparation method of the sandwich structure of this embodiment is as follows: the foam sheets and the fiber reinforced layers are stacked in sequence in the order of the first foam sheet 511, the first fiber reinforced layer 512, the second foam sheet 513, the second fiber reinforced layer 514 and the third foam sheet 515 in a preform mold, the preform mold has a mold cavity structure that is the same as the structure of the sandwich structure, and after being laid out, they are transferred to a pressing mold, at a temperature of 150°C, a molding pressure of 100kg, and a pressing time of 30min. After the molding is completed, the product is cooled and taken out to obtain the preset sandwich structure (5-1).

[0064] The paddle components of this embodiment are laid out as shown in the attached figure. Figure 1As shown, in the present utility model, the blade includes a blade surface layer, a reinforcement layer, a cushion layer and a sandwich structure, and each layer is stacked to form a blade, that is, an upper blade surface layer A1, an upper blade surface layer B2, an upper reinforcement layer 3, an upper blade cushion layer 4, a sandwich structure 5 (referring to 5-1 in this embodiment), a lower blade cushion layer 6, a lower reinforcement layer 7, a lower blade surface layer B8, and a lower blade surface layer A9 are stacked in sequence to form the blade of the present utility model. The blade surface layer includes an upper blade surface layer A1, an upper blade surface layer B2, a lower blade surface layer B8, and a lower blade surface layer A9, the reinforcement layer includes an upper reinforcement layer 3 and a lower reinforcement layer 7, and the cushion layer includes an upper blade cushion layer 4 and a lower blade cushion layer 6. The upper blade surface layer A1, the upper blade surface layer B2, the upper reinforcement layer 3, the upper blade pad thick layer 4, the lower blade pad thick layer 6, the lower reinforcement layer 7, the lower blade surface layer B8, the lower blade surface layer A9, and one end of the sandwich structure 5 all have through holes 10. And the diameters of the through holes are the same, all of which are circular through holes with a diameter of 20 mm and an outer diameter of 60 mm, and the difference between the outer diameter of the sandwich structure and the outer diameter of the entire blade is 3 mm.

[0065] The raw materials of the upper blade surface layer A1, the upper blade surface layer B2, the upper reinforcement layer 3, the upper blade pad thick layer 4, the lower blade pad thick layer 6, the lower reinforcement layer 7, the lower blade surface layer B8, and the lower blade surface layer A9 are all carbon fiber prepregs laid at an angle of 0°+±20°, and the thickness of the layer structure unit is 0.15mm. The sandwich structure 5 in this embodiment adopts the sandwich structure (5-1) obtained by the above-mentioned molding.

[0066] In the blade surface layer, the maximum width of the upper blade surface layer A1 is about 300mm, and the length, width and shape of the upper blade surface layer A1 and the lower blade surface layer A9 are consistent; the length, width and shape of the upper blade surface layer B2 and the lower blade surface layer B8 are the same, but the length and width of the upper blade surface layer B2 and the lower blade surface layer B8 are reduced by 1.5mm corresponding to the length and width of the upper blade surface layer A1 and the lower blade surface layer A9. In the reinforcement layer, starting from the center of the through hole and extending along the length direction, the shape and width of the part close to the through hole in the reinforcement layer are consistent with those of the blade surface layer, but the length of the reinforcement layer is 2 / 3 of the blade surface layer. In the cushion layer, starting from the center of the through hole and extending along the length direction, the shape and width of the part close to the through hole in the cushion layer are consistent with those of the reinforcement layer, but the length of the cushion layer is 2 / 3 of the reinforcement layer.

[0067] The cross-sectional view of the blade along the width direction in this embodiment is shown in the attached figure. Figure 2 For a clearer and more concise description, Figure 2 In the figure, 10 is the position of the through hole, 5 is the sandwich structure, and the direction passing through the through hole circle center and parallel to the length of the blade is the middle axis dividing the upper and lower sides of the blade, and the upper and lower sides correspond to the upper side and lower side of the blade along the width direction, respectively. Figure 2The A area in the figure is the leading edge of the whole blade (the leading edge of the sandwich structure, blade surface layer, and reinforcement layer), and the B area is the trailing edge of the whole blade (the trailing edge of the sandwich structure, blade surface layer, and reinforcement layer). The blade surface layer, reinforcement layer, and sandwich structure are designed according to the shape of the blade. They are streamlined structures with narrow ends and wide in the middle. The upper side surface is wide and the lower side surface is narrow. The upper side surface is thin and the lower side surface is thick. The leftmost end of the leading edge of the blade is the blade root, and the rightmost end of the trailing edge of the blade is the blade tail. The plane thickness of the sandwich structure inside the blade root is 9.5mm, which is an equal thickness area. The difference between the outer diameter of the sandwich structure and the outer diameter of the whole blade is 3mm. The length and width of the sandwich structure, reinforcement layer, and blade surface layer increase in sequence. Among them, the width of the lower side surface of the sandwich structure is 5mm smaller than the width of the lower side surface of the blade surface layer, and the width of the upper side surface of the sandwich structure is 12mm smaller than the width of the upper side surface of the blade surface layer. The length of the sandwich structure is 18mm smaller than the length of the blade surface layer.

[0068] The preparation method of the blade comprises the following steps:

[0069] With the through hole center as the positioning mark, the through hole penetrates the blade surface layer, reinforcement layer, cushion layer and sandwich structure. Figure 1 As shown, the upper blade surface layer A1, the upper blade surface layer B2, the upper reinforcement layer 3, the upper blade pad thick layer 4, the sandwich structure 5, the lower blade pad thick layer 6, the lower reinforcement layer 7, the lower blade surface layer B8, and the lower blade surface layer A9 are stacked in sequence to obtain a blade prefabricated model; the blade prefabricated model is placed in a mold with the same shape, hot-molded at 1450°C and 50Kg for 35min, cooled to 100°C and opened to obtain a blade.

[0070] The above sandwich structure (5-1) was subjected to compression, tension and shear performance tests respectively, and the results are shown in Table 1:

[0071] Table 1

[0072]

[0073] The 80PET and 75PMI materials mentioned in the table are all commercially available, and the corresponding mechanical parameters are all material data provided by the supplier. The foam sheet in this embodiment 1 uses a density of 80kg / m 3 PET, the fiber reinforcement layer adopts 100 grams of glass fiber woven cloth, the resin content of 100 grams of glass fiber woven cloth is 33%, and the glass fiber woven cloth is 67%; it can be seen that the compression, tension and shear performance of the sandwich structure of the utility model obviously exceed those of the same type of PET material, the performance of PMI material is generally better than that of PET material, and the performance of the sandwich structure of the utility model is even higher than the corresponding performance of PMI material.

[0074] Generally, if the material thickness of a CNC processing solution exceeds 20mm, the cost of the entire material is 6-10 yuan, and the processing time of a single piece is more than 25 minutes, the cost is more than 25-30 yuan; and CNC processing has a certain defect rate, about 5-10%; the overall cost of the CNC solution is between 31-40 yuan. The entire raw material cost of the blade of the utility model is within 3-6 yuan, the cutting cost and the molding cost are within 3-6 yuan, and the yield rate is basically 100%, so the cost of the blade can be controlled within 6-12 yuan, which has obvious cost advantages compared to CNC processing.

[0075] The blades used in the utility model are subjected to a high temperature during the pressing process, which is equivalent to being baked to remove water, which is helpful to stabilize the quality of the product. The stability, consistency, dimensional stability and other product qualities of the entire product are relatively better.

[0076] Example 2

[0077] The difference between this embodiment and embodiment 1 is that the structure of the sandwich structure is different. The sandwich structure of this embodiment is as shown in the attached figure. Figure 4 As shown. Among them, the sandwich structure includes a foam sheet, a fiber reinforcement layer, and a fiber reinforcement member. The foam sheet includes a first foam sheet 521, a second foam sheet 523, and a third foam sheet 525. The fiber reinforcement layer includes a first fiber reinforcement layer 522 and a second fiber reinforcement layer 524. The reinforcement member includes a first fiber reinforcement member 526, a second fiber reinforcement member 527, and a third fiber reinforcement member 528. The material, size, and shape of the foam sheet and the fiber reinforcement layer are the same as those in Example 1. The raw material of the fiber reinforcement member is a laminated structure of a composite material with 0.2mm carbon fiber prepreg 0° / 90° stacked and laid to a total thickness of 9.6mm; each fiber reinforcement member is arranged at a position close to the through hole of the blade, and a through hole consistent with the blade is provided on the fiber reinforcement member to penetrate the fiber reinforcement member, so as to facilitate communication with other components; starting from the through hole, along the length direction of the blade, the length, width and shape of the first fiber reinforcement member 526, the second fiber reinforcement member 527, and the third fiber reinforcement member 528 are the same. The fiber reinforcement has the same width and shape as the fiber reinforcement layer and a length of 150 mm.

[0078] The preparation method of the sandwich structure of this embodiment is as follows: the third fiber reinforcement 528, the third foam sheet 525, the second fiber reinforcement layer 524, the second fiber reinforcement 527, the second foam sheet 523, the first fiber reinforcement layer 522, the first foam sheet 521, and the first fiber reinforcement 526 are sequentially stacked and laid out in a preform mold, the preform mold having a mold cavity structure identical to that of the sandwich structure, and after being laid out, they are transferred to a pressing mold at a temperature of 150°C, a molding pressure of 100kg, and a pressing time of 30min. After the molding is completed, the product is cooled and taken out to obtain a preset sandwich structure (5-2).

[0079] In order to increase the bearing capacity of the blade root, a fiber layer is added to the blade root, which can effectively improve the bearing capacity of the sandwich layer at the blade root. Compared with the solution of Example 1, the solution of this embodiment can further increase the weight capacity of the blade root and improve the center of gravity of the blade, which is more conducive to blade mounting and flight stability.

[0080] Example 3

[0081] Compared with Example 1, the present embodiment is different in that the sandwich structure includes 3 foam sheets, 2 fiber reinforcements, and 2 fiber reinforcement layers; the fiber reinforcement has a through hole like the fiber reinforcement layer, and is connected to the foam sheet by a slot structure at the end away from the through hole. The fiber reinforcement and the foam sheet constitute a composite structural member, and the length, width and shape of the composite structural member are consistent with those of the fiber reinforcement layer. Protrusions forming the slot structure are provided on the 3 foam sheets, and two protrusions are provided on the first foam sheet 531, the second foam sheet 533, and the third foam sheet 535, respectively. Two matching grooves are provided on the first fiber reinforcement 536, the second fiber reinforcement 537, and the third fiber reinforcement 538, respectively, to form two slot structures. An enlarged schematic diagram of the slot structure is shown in the attached figure. Figure 7 The distance between the slot position and the central axis of the through hole is 100 mm, the width of the slot structure is 12 mm, and the depth (along the length direction of the sandwich structure) is 18 mm. The slot structure can be snapped in a right angle or with a chamfer of R3-5 mm. In this embodiment, a right angle is used.

[0082] The fiber reinforcement is a carbon fiber material with a thickness of 9.6 mm and 0.2 mm carbon fiber prepreg laid at 0° / 90°. The composite structure composed of fiber reinforcement and foam sheet is mainly designed to further enhance the force at the root of the propeller. The scheme implemented in this embodiment is also to increase the weight bearing capacity of the root of the propeller and improve the center of gravity of the blade, which is beneficial to the mounting of the blade and flight stability. At the same time, the slot structure can increase the bonding force between the foam sheet and the fiber reinforcement to prevent stress concentration.

[0083] In addition, the card slot can also be set to 1 (such as Figure 5 As shown) or more than three, the purpose is to prevent stress concentration.

[0084] Example 4

[0085] Compared with Example 3, the present embodiment differs in that the structure of the sandwich sheet is different. In addition to the slot structure of Example 3, the sandwich sheet of the present embodiment is provided with corresponding receiving slots on the first foam sheet 541, the second foam sheet 544, the third foam sheet 546 and the first fiber reinforcement 547, the second fiber reinforcement 548, and the third fiber reinforcement 549, that is, receiving slots are provided on the composite structure composed of a total of 3 fiber reinforcements and foam sheets to accommodate reinforcing ribs. The number of receiving slots is not less than two and they are arranged at equal intervals. The receiving slots can extend along the length direction or width direction of the blade. The specific method of the present embodiment is:

[0086] On the three fiber reinforcement and foam sheet composite structural parts, the positions of two receiving grooves are designed in advance on each fiber reinforcement and / or foam sheet (the positions of the reinforcement ribs are reserved, which is achieved by adding protrusions to the upper mold), and can be marked with identification lines (such as the attached Figure 8 (as shown by the dotted line in the figure), so that the receiving groove can be processed at the preset position for subsequent processing. When designing, the position of the receiving groove should extend along the length direction of the blade, and the two receiving grooves should be arranged equidistantly along the width direction, and the starting point of the receiving groove should be the same as the starting position of the card slot, that is, the distance between the starting point of the receiving groove (or reinforcing rib) and the central axis of the through hole is 100mm. When the receiving groove is processed later, it should not penetrate all the fiber reinforcements and foam sheets. In this embodiment, the depth of the receiving groove is 8mm, one of which is 0.8 times the length of the blade, and the other is 0.5 times the length of the blade.

[0087] When the receiving groove is subsequently filled, the raw material for receiving the reinforcing ribs is the same. In this embodiment, the reinforcing rib raw material is carbon fiber prepreg, the carbon fiber grade is T700, and the layers are stacked in a 0-degree laying direction, with a thickness of 0.2 mm per layer, and the layers are stacked until the required thickness, that is, the depth of the receiving groove. The sandwich structure (5-4) prepared in this embodiment has both a slot structure and a receiving groove for the reinforcing ribs.

[0088] The first foam sheet 541, the first fiber reinforcement 547, the first fiber reinforcement layer 543, the second foam sheet 544, the second fiber reinforcement 548, the second fiber reinforcement layer 545, the third foam sheet 546 and the third fiber reinforcement 549 are placed in the preform mold in this order, stacked and bonded, and then transferred to the molding mold and molded into a shape with a protruding structure preset at the same position as the above-mentioned receiving groove. After molding, a designed receiving groove is produced at the protruding position of the shape. The molding temperature is between 150°C, the molding pressure is between 50kg and 30min. The pressing time is between 30min. In the subsequent blade molding process, the reinforcing ribs are laid in the receiving groove.

[0089] Compared with Example 3, this embodiment adds reinforcing ribs. After adding corresponding protrusions to the upper surface mold, a reinforcing rib receiving groove is formed by molding. For example, in the actual blade molding process, the reinforcing ribs are placed in the receiving groove to obtain a sandwich structure containing reinforcing ribs, and the structure is formed together with the blade to obtain a blade containing reinforcing ribs, which further improves the blade's mounting capacity. The solution of this embodiment further increases the heavy (load-bearing) capacity of the blade root and improves the center of gravity of the blade, which is more conducive to blade mounting and flight stability; at the same time, the slot structure also further increases the bonding force between the foam sheet and the fiber reinforcement to prevent stress concentration.

[0090] The blade structure commonly used in the prior art has a mounting weight of about 45kg (mounted at 3 / 4 of the blade, close to the bottom), and the final product weight can be around 210g. The overall blade of the utility model weighs only 190-200 grams, which is not only lighter than the blades in the prior art, but also according to the blade test results of Examples 1-4, the blade of Example 1 is mounted at about 51Kg, the blade of Example 2 is mounted at about 55Kg, the blade of Example 3 is mounted at about 56Kg, and the blade of Example 4 is mounted at about 62Kg. The mounting weights of the four blades are ≥50Kg (all at 3 / 4 of the blade, close to the bottom), which can significantly improve the mounting capacity of the blade while reducing the weight of the blade.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit the protection scope of the utility model. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the utility model.

Claims

1. A blade, characterized in that: It comprises at least two blade surface layers, at least two reinforcement layers and a sandwich structure; The sandwich structure and the reinforcement layer are arranged between the blade surface layers; At least two reinforcement layers are stacked in sequence along the thickness direction, and the sandwich structure is arranged between any two adjacent reinforcement layers; The sandwich structure comprises at least three layers of sandwich sheets, which are stacked in sequence in the thickness direction of the sandwich structure, a fiber reinforcement layer is arranged between any two adjacent layers of sandwich sheets, and the sandwich sheets comprise foam sheets; The blade has a through hole, and the through hole penetrates the blade surface layer, the reinforcement layer and the sandwich structure.

2. The blade according to claim 1, characterized in that: The sandwich sheet also includes a fiber reinforcement, the through hole penetrates the fiber reinforcement, and the fiber reinforcement layer is made by fiber prepreg compression molding; the fiber reinforcement is snap-fitted and spliced ​​with the foam sheet, or the fiber reinforcement is stacked and combined with the foam sheet.

3. The blade according to claim 2, characterized in that: In the snap-fitting and splicing of the fiber reinforcement and the foam sheet, one of the components is provided with a groove and the other component is provided with a protrusion, and the fiber reinforcement and the foam sheet are snap-fitted through the groove and the protrusion.

4. The blade according to claim 2, characterized in that: The distance between the central axis of the through hole and the snap-fit ​​joint is 30-120 mm; the thickness of the fiber reinforcement is 3-15 mm; and the fiber reinforcement is made by compression molding of carbon fiber prepreg.

5. The blade according to any one of claims 1 to 4, characterized in that: At least one layer of sandwich sheet is provided with a receiving groove, and reinforcing ribs are provided in the receiving groove; the reinforcing ribs are made by compression molding of carbon fiber prepreg.

6. The blade according to claim 1, characterized in that The lengths of at least three layers of sandwich sheets increase or decrease in sequence in the thickness direction of the sandwich structure; the length of the sandwich structure is 15-20 mm smaller than the length of the blade surface layer, and the width of the sandwich structure is 1-8 mm smaller than the width of the blade surface layer.

7. The blade according to claim 1, characterized in that: The thickness of the foam sheet is 1.5-4.5 mm, the material of the foam sheet includes at least one of PET, PMI, PVC, PU, ​​EVA, and EPDM, and the bulk density of the foam sheet is 40-150 kg / m 3 , the compression ratio of the foam sheet is 10%-50%.

8. The blade according to claim 1, characterized in that Include at least one of the following: The blade surface layer comprises an upper blade surface layer and a lower blade surface layer, and the blade surface layer is made by compression molding of fiber prepreg; The reinforcing layer is made by compression molding of fiber prepreg; The width of the reinforcement layer is equidistantly reduced by 1-3 mm compared to the width of the blade surface layer, and the length of the reinforcement layer is 1-3 mm reduced compared to the length of the blade surface layer.

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