Continuous fiber-reinforced composite gear and method of making same

Abstract

This invention discloses a continuous fiber reinforced composite gear and its preparation method, belonging to the field of gear technology. At least one tooth body contains a continuous fiber reinforcement; a polymer layer is disposed on the outer side of the continuous fiber reinforcement; the continuous fiber reinforcement comprises multiple alternating layers of first and second layers; the angle between the continuous fiber laying direction of the first layer and the center direction of the tooth tip of the tooth body is -40° to -5°; the angle between the continuous fiber laying direction of the second layer and the center direction of the tooth tip of the tooth body is 5° to 40°. The laying direction of the continuous fiber reinforcement achieves the effect of directional reinforcement at the tooth root; the bending tensile stress generated at the tooth root can be more effectively transferred to the continuous fiber reinforcement, improving the bending load-bearing capacity, local stiffness, and fatigue life stability of the tooth root; it can avoid local stress concentration at the tooth root, improve the load-bearing capacity of the tooth body and the composite gear, increase service life, and improve the fatigue resistance of the gear under cyclic bending loads.

Description

Technical Field

[0001] This invention relates to the field of gear technology, specifically to a continuous fiber-reinforced composite gear and its preparation method. Background Technology

[0002] As automotive electronics, robotics, precision actuators, power tools, medical devices, and small transmission systems evolve towards lightweight, low-noise, high-efficiency, and low-maintenance designs, composite gears are gaining increasing attention as a replacement or supplement to metal gears. Compared to traditional metal gears, composite gears offer advantages such as lower density, better damping performance, lower operating noise, corrosion resistance, mass production via injection molding, ease of forming complex structures, and the ability to achieve self-lubricating properties through material modification. They are suitable for transmission applications requiring small to medium loads, low noise, high integration, and mass production.

[0003] Composite gears are susceptible to factors such as tooth root bending fatigue, tooth surface wear, thermal softening, creep deformation, backlash variation, and dimensional drift during actual meshing. Especially under conditions of high load, frequent start-stop, reciprocating impact, or high temperature rise, single polymer materials often cannot simultaneously meet the comprehensive requirements of gear transmission for strength, stiffness, wear resistance, dimensional stability, and low-noise operation.

[0004] For gear structures, the tooth root region usually bears periodic bending stress, which is an important area for fatigue crack initiation and tooth breakage failure in polymer gears; the tooth surface region mainly bears contact stress, rolling friction and wear.

[0005] Continuous fiber prepreg sheets are typically thin sheets with a certain fiber orientation and resin content, and can be used to reinforce composite gears. Publication number CN119308987A discloses a composite gear that combines continuous fiber reinforced composite materials and metal materials. The web is a laminated structure molded from continuous fiber reinforced composite material, specifically comprising multiple layers of carbon fiber prepreg fabric distributed sequentially along the thickness direction of the web. The layup angles of the multiple layers of carbon fiber prepreg fabric alternate between 0° / 90° and ±45°. This design achieves weight reduction while maintaining high strength and durability. The composite gear design primarily focuses on reinforcing the strength of bevel gears, without considering the different stress conditions on the tooth surface and root of spur gears or pinions.

[0006] The material properties required for the tooth root region and the tooth surface region are not entirely the same. The tooth root region focuses more on bending strength, bending stiffness, and fatigue life, while the tooth surface region focuses more on friction coefficient, wear rate, temperature rise control, and protection of mating parts.

[0007] Therefore, it is necessary to design a continuous fiber-reinforced composite gear for spur gears or pinions to improve the load-bearing capacity of the tooth root. Summary of the Invention

[0008] To address the aforementioned technical problems in the prior art, this invention provides a continuous fiber reinforced composite gear and its preparation method, thereby enhancing the root load-bearing capacity of the continuous fiber reinforced composite gear.

[0009] The first aspect of this invention discloses a continuous fiber reinforced composite gear, comprising a gear disk, an inner ring, and a plurality of teeth spaced apart on the outer periphery of the gear disk, wherein the inner ring is mounted on the inner side of the gear disk; at least one tooth body is provided with a continuous fiber reinforcement; a polymer layer is provided on the outer side of the continuous fiber reinforcement; the continuous fiber reinforcement comprises a plurality of alternating first layers and second layers; wherein the angle between the continuous fiber laying direction of the first layer and the tooth tip center direction of the tooth body is -40 to -5°; and the angle between the continuous fiber laying direction of the second layer and the tooth tip center direction of the tooth body is 5 to 40°.

[0010] Preferably, the continuous fiber reinforcement includes a connecting portion, a root portion, and a top portion connected in sequence; the connecting portion is connected to the inner ring, the root portion is located inside the tooth root of the tooth body and covers the danger zone of the tooth root; the top portion is located inside the tooth body and extends towards the tooth tip of the tooth body; the shape formed by the root portion and the top portion includes: triangle, trapezoid, or trapezoidal shape; One type of trapezoidal shape includes: a first trapezoid at the root and a second trapezoid at the top, with a smooth transition between the first and second trapezoids, and on a projection plane perpendicular to the gear axis, the inclination angle of the side of the first trapezoid is greater than the inclination angle of the side of the second trapezoid.

[0011] Preferably, the continuous fiber reinforcement comprises a plurality of reinforcing layers, the reinforcing layers including a first reinforcing layer and a second reinforcing layer; the first reinforcing layer and the second reinforcing layer are alternately stacked; The first enhancement layer comprises multiple first layers spliced ​​together via a splicing interface; The second enhancement layer comprises multiple second layers spliced ​​together via splicing interfaces; The splicing interfaces of adjacent first and second reinforcement layers are offset on the projection plane perpendicular to the gear axis, with an offset distance of 10% to 50% of the tooth spacing.

[0012] Preferably, the thickness of the polymer layer along the normal direction of the tooth surface at the meshing surface is 0.05*AD to 1.5*AD, where AD is the module; The axial thickness of the continuous fiber reinforcement is 40-95% of the tooth width; The thickness of the first or second layer is 0.03 to 0.50 mm; the total number of the first and second layers is 10 to 200. The splicing structure of the splicing interface is selected from sutures, needle-punched fibers, tufted fibers, Z-direction connecting fibers, Z-pins, thermoplastic resin connecting films, and local welding points; The splicing interface is set in the inner edge area, outer edge area, or non-primary tensile area of ​​the reinforcement layer.

[0013] Preferably, the edge structure of the continuous fiber reinforcement is provided with roughened surface, pores, through holes, grooves, notches, chamfers, and edge sealing layer; The polymer layer is bonded to the edge structure; The inner ring is a metal inner ring with a shaft hole at its center and a mechanical fitting structure on its outer periphery that mates with the continuous fiber reinforcement. The mechanical fitting structure is selected from: annular groove, axial groove, knurling, radial flange, and axial limiting structure.

[0014] Preferably, the polymer layer matrix can be selected from polyoxymethylene, polyamide, polyphenylene sulfide, polyphthalamide, polyetheretherketone, polyketone, liquid crystal polymer, and polyimide; The polymer layer also includes any of the following components or a combination thereof: Polytetrafluoroethylene, graphite, molybdenum disulfide, hexagonal boron nitride, polyimide micro powder, silicone lubricants, wax lubricants, wear-resistant fillers, thermally conductive fillers, dimensionally stabilizing fillers, toughening agents, antioxidants, heat stabilizers, nucleating agents, or processing aids.

[0015] Preferably, the first and second layers are continuous fiber prepreg sheets; The resin matrix of the continuous fiber prepreg is selected from: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyphthalamide, polyamide, polyoxymethylene, polyetherimide, polyimide, liquid crystal polymer, epoxy resin, phenolic resin, and bismaleimide resin. The continuous fibers in the continuous fiber prepreg are selected from: unidirectional continuous carbon fiber, continuous glass fiber, continuous aramid fiber, basalt fiber, and polyimide fiber.

[0016] Preferably, the fiber orientations of the first and second layers are respectively represented as follows: ; in, The fiber direction of the first layer, The fiber direction of the second layer, N Expressed as the number of teeth, For the first i The direction of the center of the tooth tip of each tooth body M Expressed as the deflection angle of the continuous fiber, ranging from 5 to 40°. i It is an integer. The direction of the center of the tooth tip of the reference tooth body.

[0017] The second aspect of the present invention provides a method for preparing the above-mentioned continuous fiber reinforced composite gear, comprising the following steps: laying continuous fiber prepreg sheets; A continuous fiber prepreg is cut to obtain a reinforcing unit corresponding to a tooth body. The reinforcing unit includes a first reinforcing unit containing a first layer and a second reinforcing unit containing a second layer. Multiple reinforcement units are circumferentially spliced ​​together to obtain an reinforcement layer; After the reinforcing layers are stacked, they are hot-pressed to obtain a continuous fiber reinforced body; Continuous fiber reinforcement is connected to the inner ring to obtain a pre-assembled structure; The pre-assembled structure is injection-compression molded to obtain a continuous fiber-reinforced composite gear.

[0018] Preferably, a splicing interface is provided between adjacent reinforcing units. The splicing interface is provided with: an overlapping area, a stepped splicing area, a mitering area, or a complementary splicing area, and the adjacent reinforcing units partially overlap at the splicing interface.

[0019] Preferably, the injection compression molding method includes: After the pre-assembled structure is placed into the molding die, self-lubricating polymer melt is injected into the mold cavity of the molding die, and injection compression coating molding is performed to obtain a continuous fiber reinforced composite gear. The polymer melt comprises the following components by weight percentage: 80% polyetheretherketone; 10% polytetrafluoroethylene; 5% graphite; and 5% chopped carbon fiber.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The laying direction of the continuous fiber reinforcement has the effect of directional reinforcement of the tooth root; the bending tensile stress generated at the tooth root can be more effectively transferred to the continuous fiber reinforcement, improving the bending load capacity, local stiffness and fatigue life stability of the tooth root; it can avoid local stress concentration at the tooth root, improve the load-bearing capacity of the tooth body and composite gear, improve service life, and improve the fatigue resistance of the gear under cyclic bending load. Attached Figure Description

[0021] Figure 1 This is a partial sectional view of a compound gear; Figure 2 This is a schematic diagram of the continuous fiber reinforcement laid within the tooth body; Figure 3 This is a schematic diagram of the pre-assembled gear structure; Figure 4 This is a schematic diagram of the injection compression of the pre-assembled structure; Figure 5 This is a logic block diagram of the composite gear manufacturing method.

[0022] Markings in the diagram: 1. Inner ring; 2. Gear disc; 3. Tooth body; 4. Tooth tip; 5. Tooth surface; 6. Tooth flank; 7. Tooth root; 8. Continuous fiber reinforcement; 81. Root; 82. Connecting part; 83. Top; 9. Danger zone; 10. Hot press mold; 11. First layer; 12. Second layer; 13. Interface; 14. Enhancement layer; 15. Pre-assembled structure; 17. Polymer melt; 19. Molding mold. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] The present invention will now be described in further detail with reference to the accompanying drawings: This invention provides a continuous fiber-reinforced composite gear, such as... Figures 1-4 The device includes a toothed disc 2 and multiple teeth 3 spaced apart on the outer periphery of the toothed disc 2. An inner ring 1 is located in the center of the toothed disc 2. A polymer layer is provided on the outer side of the continuous fiber reinforcement 8 and the outer side of the toothed disc 2. Continuous fiber reinforcement 8 is disposed within the teeth 3, such as... Figure 2 The continuous fiber reinforcement 8 comprises multiple alternating layers of first layer 11 and second layer 12. The angle between the continuous fiber layup direction of the first layer 11 and the center direction of the tooth tip 4 of the tooth body 3 is -40° to -5°. The angle between the continuous fiber layup direction of the second layer 12 and the center direction of the tooth tip 4 of the tooth body 3 is 5° to 40°. The tooth body 3 has a tooth root 7 on the side facing the tooth disk 2 and a tooth tip 4 on the side away from the tooth disk 2. The continuous fiber reinforcement 8 extends towards the inner ring 1 on the side away from the tooth body 3 and towards the tooth tip 4 on the opposite side, covering the critical area 9 of the tooth root 7. The tooth surface 5 on one circumferential side of the tooth body 3 and the outer side of the tooth disk 2 are covered with a polymer layer. There is a tooth flank 6 between the tooth tip 4 and the tooth root 7. The area near the critical area 9 of the tooth root is usually a critical area where bending fatigue cracks are prone to initiation.

[0025] The laying direction of the continuous fiber reinforcement 8 has the effect of directional reinforcement of the tooth root; the bending tensile stress generated by the tooth root 7 can be more effectively transferred to the continuous fiber reinforcement 8, thereby improving the tooth root's bending load capacity, local stiffness and fatigue life stability; it can avoid local stress concentration at the tooth root, improve the load-bearing capacity of the tooth body 3 and the composite gear, improve service life, and improve the gear's fatigue resistance under cyclic bending load.

[0026] Danger zone 9 refers to the area near the transition curve of tooth root 7, which bears the maximum bending tensile stress during gear meshing and is the initiation source of fatigue cracks.

[0027] The compound gear can form the following working path and pass through sequentially: Drive shaft or other connecting parts, metal inner ring 1, tooth root oriented continuous fiber reinforcement 8, tooth root 7, self-lubricating polymer tooth surface 5, and mating gear.

[0028] like Figure 3 In the continuous fiber reinforcement 8, the splicing interfaces 13 between the first layers 11 of adjacent circumferentially adjacent tooth bodies 3 are spliced ​​together to obtain a first reinforcement layer; the splicing interfaces 13 between the second layers 12 of adjacent tooth bodies 3 are spliced ​​together to obtain a second reinforcement layer. The splicing interfaces 13 of adjacent reinforcement layers 14 are staggered on the projection plane perpendicular to the gear axis, i.e., they do not overlap. However, the splicing method is not limited to this; the first layers 11 and second layers 12 of adjacent tooth bodies 3 can also be spliced ​​together.

[0029] Among them, the first layer 11 and the second layer 12 are continuous fiber prepreg sheets. After the continuous fiber prepreg sheets are stacked and laid, they are hot-pressed to form a continuous fiber reinforcement 8.

[0030] The edges of the continuous fiber reinforcement 8 can be roughened, have pores, through holes, grooves, notches, chamfers, edge sealing layers, or other edge structures that facilitate the bonding of the outer polymer layer. The polymer melt 17 can enter the edge structure. After cooling and solidification, a local mechanical interlocking or interfacial composite structure is formed, thereby improving the bonding stability between the polymer layer and the continuous fiber reinforcement 8 and reducing the risk of outer layer peeling, edge lifting, or local delamination during gear operation.

[0031] like Figure 2 and Figure 3 The continuous fiber reinforcement 8 includes a connecting portion 82, a root portion 81, and a top portion 83 connected in sequence; the connecting portion 82 is connected to the inner ring 1, the root portion 81 is disposed inside the tooth root 7, and the top portion 83 is disposed inside the tooth body 3. The root portion 81 and the top portion 83 have a triangular or trapezoidal structure. More specifically, the root portion 81 has a first trapezoidal shape, and the top portion 83 has a second trapezoidal shape. The first and second trapezoids are smoothly transitioned, and on the projection plane perpendicular to the gear axis, the inclination angle of the side of the first trapezoid is greater than the inclination angle of the side of the second trapezoid.

[0032] The porosity of the continuous fiber reinforcement 8 is no greater than 5%, preferably no greater than 2%. The porosity between adjacent layers of the continuous fiber reinforcement 8... The inner ring 1 can be made of metal, with a central axial hole. The outer circumference of the inner ring 1 can be provided with annular grooves, axial grooves, knurling, local protrusions, radial flanges, axial limiting structures, or other mechanical mating / locking structures to increase the contact area and mechanical interlocking force between the inner ring and the continuous fiber reinforcement 8. This reduces the risk of circumferential slippage, axial movement, loosening, or detachment of the metal inner ring relative to the outer composite structure under alternating torque, impact loads, or temperature changes. The mechanical mating structure can cooperate with the inner edge, positioning hole, or mating surface of the tooth root oriented continuous fiber prepreg laminate reinforcement, ensuring that the continuous fiber reinforcement 8 maintains a predetermined position during the closing, melt injection, and compression coating processes within the molding die 19. This reduces the adverse effects of continuous fiber reinforcement 8 displacement on the tooth root reinforcement position and tooth coating thickness. The material of the inner ring 1 can be steel, stainless steel, aluminum alloy, titanium alloy, copper alloy, powder metallurgy metal materials, or other metal materials with sufficient strength, rigidity, and dimensional stability.

[0033] The polymer layer not only covers the outer side of the tooth body 3 and the tooth disc 2, but also at least partially fills the interior of the continuous fiber bundles and / or the gaps between adjacent continuous fiber bundles.

[0034] The self-lubricating polymer layer can be made of PEEK-based self-lubricating composite material, formed by injection compression molding. The polymer layer covers the radial outer edge, two axial end faces, and local splicing edges of the continuous fiber reinforcement 8, forming a complete gear and its tooth surface 5 meshing surface. The polymer layer encapsulates the root-oriented continuous fiber prepreg laminate reinforcement inside, so that the continuous fibers are not directly exposed on the tooth meshing surface.

[0035] The matrix of the polymer layer can be selected from polyoxymethylene, polyamide, polyphenylene sulfide, polyphthalamide, polyetheretherketone, polyketone, liquid crystal polymer, polyimide, or other engineering plastics or high-performance engineering plastics suitable for gear meshing. The self-lubricating component of the polymer layer can be selected from polytetrafluoroethylene, graphite, molybdenum disulfide, hexagonal boron nitride, polyimide micropowder, silicone-based lubricants, wax-based lubricants, or other solid lubricating materials capable of reducing the coefficient of friction, improving wear performance, or promoting the formation of a transfer film. The above materials are only used to illustrate the optional material systems and do not constitute a limitation on the scope of protection of this invention.

[0036] The polymer layer may also include wear-resistant fillers, thermally conductive fillers, dimensionally stabilizing fillers, toughening agents, antioxidants, heat stabilizers, nucleating agents, or processing aids. The wear-resistant fillers can be used to improve the wear resistance of the tooth surface; the thermally conductive fillers can be used to improve the frictional heat diffusion capacity of the tooth surface and reduce local temperature rise; the dimensionally stabilizing fillers can be used to reduce dimensional drift caused by molding shrinkage, thermal expansion, or moisture absorption; the toughening agents can be used to improve the impact resistance of the tooth root transition surface or the working layer of the tooth surface; and the processing aids can be used to improve the flowability and tooth profile replication capability of the self-lubricating polymer composite melt during injection compression molding.

[0037] In a preferred embodiment, the thickness of the polymer layer along the normal direction of the tooth surface at the meshing surface is 0.05AD to 1.5AD, preferably 0.10AD to 0.50AD, where AD is the gear module. The minimum distance between the outer edge of the continuous fiber reinforcement 8 and the meshing surface of the tooth surface is not less than 0.03AD, preferably not less than 0.05AD.

[0038] In a preferred embodiment, both the first layer 11 and the second layer 12 are continuous fiber prepreg sheets. The thickness of a single continuous fiber prepreg sheet after hot pressing is 0.03–0.50 mm, preferably 0.08–0.30 mm; the continuous fiber reinforcement comprises 10–200 layers of continuous fiber prepreg sheets, preferably 30–120 layers. The continuous fibers in the same layer of continuous fiber prepreg sheet are arranged substantially parallel to each other along a predetermined direction in the plane of the prepreg sheet, and the center distance between adjacent continuous fiber bundles or adjacent continuous fiber layup trajectories is 0.05–5.0 mm, preferably 0.10–2.0 mm. The porosity of the continuous fiber reinforcement 8 after hot pressing is not greater than 5%, preferably not greater than 2%.

[0039] Adjacent continuous fiber prepreg sheets are bonded together by hot-pressing to form an interlayer bonding interface, enabling the continuous fiber reinforcement to form an integral laminated structure. Furthermore, the interlayer bonding can be strengthened by one or more of the following local interlayer bonding structures: sutures, braided threads, needle-punched fibers, tufted fibers, Z-direction connecting fibers, Z-pins, thermoplastic resin connecting films, thermoplastic resin meshes, local hot-pressed weld points, ultrasonic weld points, or laser weld points. Additionally, the splicing structure of the splicing interface 13 can be selected from sutures, needle-punched fibers, tufted fibers, Z-direction connecting fibers, Z-pins, thermoplastic resin connecting films, and local weld points.

[0040] The splicing structure or interlayer connection structure is set in the inner edge region, outer edge region, or non-primary tensile region of the reinforcing layer. The non-primary tensile region includes, but is not limited to, the region on the gear disk 2 located between adjacent teeth 3, which does not bear the primary bending tensile stress during normal gear transmission.

[0041] It can improve the integrity and anti-delamination ability of continuous fiber reinforcement in the tooth width direction, and reduce the risk of interlayer slippage, local delamination, splice interface opening or edge warping during the handling, assembly, hot pressing and injection compression overmolding of multilayer prepreg sheets.

[0042] Example 1 provides a fabrication process for a continuous fiber-reinforced composite gear. Key details of the composite gear are shown in Table 1.

[0043] Table 1 like Figure 5 As shown, the preparation method includes the following steps: Step S1: Laying continuous fiber prepreg sheets.

[0044] The resin matrix of the continuous fiber prepreg sheet is made of polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylene sulfide (PPS), polyphthalamide (PPA), polyamide (PA), polyoxymethylene (POM), polyetherimide (PEI), polyimide (PI), liquid crystal polymer (LCP), epoxy resin, phenolic resin, bismaleimide resin, or blends thereof. The resin matrix content is 20 wt% to 70 wt%, preferably 30 wt% to 55 wt%.

[0045] The continuous fiber is unidirectional continuous carbon fiber, with a volume fraction of 50%–60%, 30%–70%, preferably 45%–60%, and in specific preparation, a volume fraction of 55%. The nominal thickness of the single-layer continuous fiber prepreg after hot pressing is 0.20 mm. The continuous fiber can also be continuous glass fiber, continuous aramid fiber, basalt fiber, polyimide fiber, or a mixture of these fibers.

[0046] A total of 80 layers of continuous carbon fiber reinforced prepreg are used, with 40 layers of the first layer (11) and 40 layers of the second layer (12). Layers 11 and 12 are stacked alternately along the gear axis. Based on a nominal thickness of 0.20 mm after hot pressing, the target axial thickness of the continuous fiber reinforcement 8 is 80 × 0.20 mm = 16 mm. The 16 mm thick continuous fiber reinforcement 8 is centrally arranged along the 20 mm tooth width direction, leaving approximately 2 mm of polymer coating thickness between its two axial end faces and the two end faces of the final composite gear. Considering the initial thickness of the prepreg, the hot pressing compaction rate, and the interlayer resin flow, the actual thickness of the laminated reinforcement after hot pressing can be controlled between 15.5 and 16.5 mm. Correspondingly, the self-lubricating polymer coating thickness on one side of the two axial end faces is approximately 1.75 to 2.25 mm.

[0047] The first layer 11 and the second layer 12 form angles of -30° and 30° with the fiber laying direction and the center direction of the tooth tip 4 of the tooth body 3, respectively. Local coordinate systems are established for each of the 30 teeth in the projection plane of the end face perpendicular to the gear axis. For any target tooth, the radial direction from the gear center to the center of the tooth tip is taken as the local reference direction of that tooth. For the reference tooth, its tooth tip center direction is defined as 90°, then: the local laying direction of the continuous fibers in the first layer 11 is 60°; the local laying direction of the continuous fibers in the second layer is 120°. That is, the first layer 11 and the second layer 12 are deflected by -30° and +30° respectively relative to the center direction of the tooth tip 4, and the first layer 11 and the second layer 12 are arranged in a mirror image along the center direction of the tooth tip 4. The continuous fibers in layer A mainly extend along the target load transmission direction of one tooth root region, and the continuous fibers in layer B mainly extend along the target load transmission direction of another tooth root region. After the first layer 11 and the second layer 12 are alternately stacked along the gear axis, a bidirectional, mirror-like continuous fiber reinforcement path is formed in the tooth root region on both sides of a single tooth body 3. It is suitable for forward transmission, reverse transmission and reciprocating transmission conditions.

[0048] In this embodiment, the number of teeth is 30, and the circumferential angle R between two adjacent teeth 3 is: ,in N This is expressed as the number of teeth.

[0049] For the i Each tooth body, its local reference direction It can be represented as: ; The fiber orientations of the first layer 11 and the second layer 12 are respectively represented as follows: ; in, The fiber direction of the first layer 11, The fiber orientation is for the second layer (12). M represents the continuous fiber deflection angle, ranging from 5 to 40°. i Integers between 0 and 29 The direction of the center of the tooth tip of the reference tooth body 3.

[0050] 60° and 120° are angles relative to the local coordinate system of the reference tooth 3. For other teeth 3 (also called gear teeth), the continuous fiber orientation rotates synchronously with the circumferential position of the corresponding tooth, and the continuous fiber reinforcement 8 does not adopt a fixed 60° or 120° layup direction in each tooth 3.

[0051] Step S2: Cut the continuous fiber prepreg to obtain a reinforcing unit corresponding to a tooth 3.

[0052] To ensure that each tooth 3 has a continuous fiber reinforcement path that matches the force direction of its own tooth root 7, instead of using a single continuous fiber prepreg sheet with a unified global orientation to directly form a complete reinforcement, a single continuous fiber reinforcement unit is designed for each tooth.

[0053] Each reinforcing unit covers at least: the tooth root region / danger zone; the tooth root transition region on both sides of the tooth body 3; the load transfer region extending from the tooth root region 7 towards the inner metal ring 1, i.e., covering the tooth disk region between the tooth root 7 and the inner ring 1; and the splicing region connected or overlapping with adjacent reinforcing units. The tooth root region has a triangular or trapezoidal structure.

[0054] According to predetermined fiber orientation, load transfer zone, tooth root region, and splicing region, single-layer or few-layer continuous carbon fiber reinforced PEEK prepreg sheets are cut to form reinforcing units. Each reinforcing unit includes a first reinforcing unit containing a first layer and a second reinforcing unit containing a second layer.

[0055] The cutting boundary is determined by the local fiber orientation of the corresponding gear teeth and the target reinforcement area, rather than being arbitrarily selected after the layup is completed. If necessary, the edges of the cut reinforcement can be chamfered, rounded, deburred, edge-sealed, or resin-sealed to reduce the risk of loose fiber ends, edge delamination, or local exposure during subsequent overmolding.

[0056] Step S3: Circumferentially splice multiple reinforcement units to obtain an reinforcement layer.

[0057] The reinforcement layer includes a first reinforcement layer and a second reinforcement layer. Multiple first reinforcement units are circumferentially spliced ​​together to obtain the first reinforcement layer; multiple second reinforcement units are circumferentially spliced ​​together to obtain the second reinforcement layer. Taking a 30-tooth tooth as an example, 30 first reinforcement units are spliced ​​together to obtain one first reinforcement layer; 30 second reinforcement units are spliced ​​together to obtain one second reinforcement layer.

[0058] The splicing boundary between two adjacent reinforcing units is set in the non-primary tension area between adjacent teeth to avoid the splicing boundary coinciding with the dangerous section of the tooth root.

[0059] In one specific embodiment, the circumferential edges of adjacent single-tooth reinforcement units are connected in a flat joint manner, and the splicing boundaries of adjacent reinforcement units are staggered circumferentially in the reinforcement stack.

[0060] In another specific embodiment, an overlapping area, a stepped splicing area, a miter joint area, or a complementary splicing area is provided between adjacent reinforcing units, so that adjacent reinforcing units form a partial overlap in the circumferential direction.

[0061] The splicing boundaries of different reinforcement layers are staggered in axial projection position, i.e., not set at the same axial projection position. Preferably, they are staggered by 10% to 50% of a tooth spacing to reduce the risk of local weakness caused by the splicing boundary being continuous along the gear axis. By designing, cutting, and splicing each individual tooth separately, all 30 teeth can have a continuous fiber orientation that matches their local tooth root reinforcement direction.

[0062] Step S4: Stack the reinforcing layers and hot press them to obtain a continuous fiber reinforced body 8.

[0063] The first and second reinforcing layers are stacked alternately. During the stacking process, the splicing boundaries 13 in different layers are staggered circumferentially to avoid multiple splicing boundaries coinciding in the tooth width direction.

[0064] After lamination, the 80-layer prepreg assembly is placed into the hot press mold 10 for hot pressing and compaction, so that the PEEK resin of different reinforcing units, different circumferential splicing areas and adjacent A and B layers are fused together to form an integral tooth root oriented continuous fiber reinforcement 8 with an axial thickness of about 16mm.

[0065] See Table 2 for specific hot pressing parameters.

[0066] Table 2 In another specific embodiment, a plurality of sub-reinforcements are prepared; then the plurality of sub-reinforcements are hot-pressed to form a complete continuous fiber reinforcement 8.

[0067] Step S5: Connect the continuous fiber reinforcement 8 to the inner ring 1 to obtain the pre-assembled structure.

[0068] The inner ring 1 is made of 40Cr steel and has a shaft hole in its center. The outer circumference of the metal inner ring 1 is provided with annular grooves, axial grooves, knurling, local protrusions or other mechanical mating structures.

[0069] The continuous fiber reinforcement 8 is assembled on the outer periphery of the metal inner ring, and the two are kept coaxial by the positioning structure of the mating surface, positioning groove, positioning pin or mold to form a pre-assembled structure 5.

[0070] The inner metal ring serves as the shaft-hole connection, center positioning, and torque transmission function; the tooth root oriented continuous fiber prepreg laminate reinforcement is used to form a continuous load transmission path between the inner metal ring 1 and the tooth root bearing area.

[0071] Step S6: Inject and compress the pre-assembled structure to obtain a continuous fiber-reinforced composite gear.

[0072] like Figure 3 and Figure 4The pre-assembled structure 15 is placed into the molding mold 19, and the self-lubricating polymer melt 17 is injected into the mold cavity of the molding mold 19 for injection compression coating molding.

[0073] In one specific embodiment, the polymer melt comprises the following components by weight percentage: PEEK resin: 80%; polytetrafluoroethylene (PTFE): 10%; graphite: 5%; chopped carbon fiber: 5%. However, it is not limited to this, the polymer melt may also include molybdenum disulfide, boron nitride, ceramic particles, or other friction-reducing, wear-resistant, and thermally conductive fillers.

[0074] During injection compression, the melt temperature is 380–410°C, and the temperature of the molding die 19 is 170–210°C. After injection, the molding die 19 is further closed for compression and pressure holding. After cooling to the demolding temperature, the die is opened and the part is removed.

[0075] The self-lubricating polymer melt coats the radial outer edge, two axial end faces, and locally spliced ​​edges of the continuous fiber reinforcement 8, forming a complete gear tooth profile and meshing surface. The final result is a composite gear with a tooth width of 20 mm, an axial thickness of approximately 16 mm for the internal reinforcement, and a coating thickness of approximately 2 mm on each axial side; this is designated as the first gear.

[0076] If necessary, the demolded composite gear can undergo post-processing such as gate removal, flash removal, annealing, humidity conditioning, dimensional inspection, or tooth profile inspection. The hot-pressing temperature, pressure, and time can be determined based on the type of resin matrix of the continuous fiber prepreg, the thickness of the continuous fiber prepreg, the number of layers, and the target interlayer bonding strength.

[0077] Comparative Example 1 provides a second gear without continuous fiber reinforcement. The gear dimensions, inner metal ring, and outer self-lubricating polymer material are the same as in Example 1, but without the continuous fiber reinforcement 8.

[0078] Example 2 provides a third gear with a 90° single-layer layup. It uses 80 layers of continuous carbon fiber reinforced PEEK prepreg, with the continuous fibers laid along the center direction of the local tooth tip of each gear tooth.

[0079] Example 3 provides a fourth gear with alternating 45° / 135° layups. It employs 80 layers of continuous carbon fiber reinforced PEEK prepreg, with the first layer at 45° and the second layer at 135°, stacked alternately. The cutting, splicing, and injection compression methods are the same as in Example 1.

[0080] Example 4 provides a fifth gear with alternating 30° / 150° layups. It employs 80 layers of continuous carbon fiber reinforced PEEK prepreg, with the first layer at 30° and the second layer at 150°, stacked alternately. The cutting, splicing, and injection compression methods are the same as in Example 1.

[0081] Example 5 provides a sixth gear with isotropic plying. Four local directions—0°, 45°, 90°, and 135°—are periodically alternated in plying, for a total of 80 layers. The fiber volume fraction, reinforcement thickness, single-tooth splicing method, metal inner ring, self-lubricating polymer tooth surface working layer, and molding conditions are all the same as in Example 1.

[0082] Each gear uses a standard involute spur gear with a module of 2 mm, 30 teeth, a pressure angle of 20°, and a tooth width of 20 mm. The pulsating fatigue evaluation conditions are set as follows: maximum pulsating normal load (F_max) graded according to the load-bearing capacity of different schemes; minimum clamping load (F_min=100 N); loading frequency (f=30 Hz); gear temperature of 70℃; load waveform approximately sinusoidal; and a specified fatigue life of (1.0*10^6) N. 6 The test cycle was repeated 10 times; failure criteria included tooth root fracture, tooth surface shear fracture, significant plastic deformation, interface debonding, or a composite material failure index reaching 1. Table 3 shows the pulsation test fatigue results for each gear.

[0083] Table 3 The relative fatigue load capacity is the ratio of each gear to the second gear. The specified life is (1.0 * 10^6)^2. 6 At this time, the predicted pulsating normal load of the non-continuous fiber reinforced scheme is about 2050 N, while the first gear with 60° / 120° mirror alternating layup can reach about 2900 N, an improvement of about 41%.

[0084] When the maximum pulsating normal load is 2000 N, the life of the second gear without continuous fiber reinforcement is approximately (1.5 * 10⁻⁶). 6 The lifespan of the first gear is (2.0 * 10) times, while the lifespan of the first gear is (2.0 * 10) times. 7 (This is repeated approximately 13 times, reaching the speed of the second gear.)

[0085] The sixth gear, employing alternating 45° / 135° layups, also exhibits good directional reinforcement, with its predicted load-bearing capacity being approximately 7% lower than that of the 60° / 120° layup. The fifth gear, employing 30° / 150° layups, and the fourth gear, employing quasi-isotropic layups, show a decrease in their effective axial load-bearing component and a corresponding reduction in fatigue load-bearing capacity due to the increased angle between some continuous fibers and the main tensile direction at the tooth root.

[0086] The results indicate that when continuous fibers are arranged along the main tensile load-bearing path in the tooth root region on both sides, the continuous fibers can bear a larger proportion of the tooth root tensile load and diffuse the load from the tooth root region toward the rim and the inner metal ring, thereby reducing the local stress in the PEEK matrix and the self-lubricating polymer tooth surface working layer. This improves load capacity, lifespan, and fatigue load-bearing capacity.

[0087] This invention divides the central connecting area of ​​the inner ring, the tooth root bearing area of ​​the tooth body 3, and the friction working area of ​​the tooth surface 5 into zones. The metal inner ring 1 is used to improve the connection strength, dimensional stability, and torque transmission reliability of the shaft hole area. A tooth root oriented continuous fiber reinforcement 8 is provided on the outside of the metal inner ring 1. The continuous fiber reinforcement 8 extends at least partially to the rim area and near the critical section of the tooth root, and its fiber orientation is designed according to the load transmission direction of the rim area and / or the principal tensile stress direction of the critical section of the tooth root, so as to form a continuous, oriented, and designable load-bearing path in the critical stress area of ​​the tooth root, thereby improving the bending load-bearing capacity and local stiffness of the tooth root. A self-lubricating polymer layer is provided on the outside of the continuous fiber reinforcement 8, so that the polymer layer forms the tooth profile and tooth surface meshing surface of the tooth side 6, and the continuous fiber is not directly exposed to the tooth surface meshing surface, thereby taking into account the wear resistance of the tooth surface, self-lubrication and protection of the mating parts.

[0088] The following partitions of this invention have excellent synergistic effects: the tooth root bearing capacity of the continuous fiber reinforcement 8, the tooth surface friction of the polymer layer, and the center connection of the inner ring, effectively improving the load-bearing capacity of the tooth body and the composite gear, increasing service life, and enhancing the fatigue resistance of the gear under cyclic bending loads. The preparation method effectively ensures the reliable connection and stability of the product.

[0089] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A continuous fiber-reinforced composite gear, characterized by, It includes a toothed disc (2), an inner ring (1), and multiple teeth (3) spaced apart on the outer periphery of the toothed disc (2), with the inner ring (1) installed on the inner side of the toothed disc (2); At least one tooth body (3) is provided with a continuous fiber reinforcement (8); a polymer layer is provided on the outside of the continuous fiber reinforcement (8); The continuous fiber reinforcement (8) includes multiple alternating layers of first layer (11) and second layer (12); wherein the angle between the continuous fiber laying direction of the first layer (11) and the center direction of the tooth tip (4) of the tooth body (3) is -40 to -5°; and the angle between the continuous fiber laying direction of the second layer (12) and the center direction of the tooth tip (4) of the tooth body (3) is 5 to 40°.

2. The continuous fiber-reinforced composite gear according to claim 1, characterized in that, The continuous fiber reinforcement (8) includes a connecting part (82), a root part (81) and a top part (83) connected in sequence; the connecting part (82) is connected to the inner ring (1), the root part (81) is located inside the tooth root (7) of the tooth body (3) and covers the danger zone (9) of the tooth root (7); the top part (83) is located inside the tooth body (3) and extends toward the tooth tip (4) of the tooth body (3); The shape formed by the root (81) and the top (83) includes: triangle, trapezoid or trapezoidal; One type of trapezoidal shape includes: a first trapezoid at the root (81) and a second trapezoid at the top (83), with the first and second trapezoids smoothly transitioning, and on a projection plane perpendicular to the gear axis, the inclination angle of the side of the first trapezoid is greater than the inclination angle of the side of the second trapezoid.

3. The continuous fiber-reinforced composite gear of claim 1, wherein, The continuous fiber reinforced body (8) includes multiple reinforcing layers, the reinforcing layers including a first reinforcing layer and a second reinforcing layer; the first reinforcing layer and the second reinforcing layer are alternately stacked; The first enhancement layer includes multiple first layers (11) spliced ​​together through splicing interface (13); The second enhancement layer includes multiple second layers (12) spliced ​​together via splicing interface (13); The splicing interface (13) of the first reinforcing layer and the splicing interface (13) of the adjacent second reinforcing layer are offset on the projection plane perpendicular to the gear axis, and the offset distance is 10% to 50% of the tooth spacing.

4. The continuous fiber reinforced composite gear according to claim 3, characterized in that, The thickness of the polymer layer along the normal direction of the tooth surface at the meshing surface is 0.05*AD to 1.5*AD, where AD is the gear module; The axial thickness of the continuous fiber reinforcement is 40-95% of the tooth width; The thickness of the first layer (11) or the second layer (12) is 0.03 to 0.50 mm; the total number of layers of the first layer (11) and the second layer (12) is 10 to 200. The interlayer connection structure between adjacent first and second layers is selected from: sutures, needle-punched fibers, tufted fibers, Z-direction connecting fibers, Z-pins, thermoplastic resin connecting films, and local welding points; The splicing interface (13) is set in the inner edge area, outer edge area or non-primary tensile area of ​​the reinforcement layer.

5. The continuous fiber-reinforced composite gear according to claim 1, characterized in that, The edge structure of the continuous fiber reinforcement (8) is provided with roughened surface, pores, through holes, grooves, notches, chamfers, and sealing layer; The polymer layer is bonded to the edge structure; The inner ring (1) is a metal inner ring. The center of the inner ring (1) is provided with a shaft hole and the outer periphery is provided with a mechanical fitting structure that cooperates with the continuous fiber reinforcement (8). The mechanical fitting structure is selected from: annular groove, axial groove, knurling, radial flange and axial limiting structure.

6. The continuous fiber-reinforced composite gear according to claim 1, characterized in that, The polymer layer matrix can be selected from polyoxymethylene, polyamide, polyphenylene sulfide, polyphthalamide, polyetheretherketone, polyketone, liquid crystal polymer, and polyimide; The polymer layer also includes any of the following components or a combination thereof: Polytetrafluoroethylene, graphite, molybdenum disulfide, hexagonal boron nitride, polyimide micro powder, silicone lubricants, wax lubricants, wear-resistant fillers, thermally conductive fillers, dimensionally stabilizing fillers, toughening agents, antioxidants, heat stabilizers, nucleating agents or processing aids; The first layer (11) and the second layer (12) are continuous fiber prepreg sheets; The resin matrix of the continuous fiber prepreg is selected from: polyetheretherketone, polyetherketoneketone, polyphenylene sulfide, polyphthalamide, polyamide, polyoxymethylene, polyetherimide, polyimide, liquid crystal polymer, epoxy resin, phenolic resin, and bismaleimide resin. The continuous fibers in the continuous fiber prepreg are selected from: unidirectional continuous carbon fiber, continuous glass fiber, continuous aramid fiber, basalt fiber, and polyimide fiber.

7. The continuous fiber reinforced composite gear according to claim 1, characterized in that, The fiber orientations of the first layer (11) and the second layer (12) are respectively represented as follows: ； in, The fiber direction of the first layer (11) For the fiber direction of the second layer (12), N Expressed as the number of teeth, For the first i The direction of the center of the tooth tip of each tooth body M Expressed as the deflection angle of the continuous fiber, ranging from 5 to 40°. i It is an integer. The direction of the center of the tooth tip of the reference tooth body.

8. A method for preparing a continuous fiber-reinforced composite gear as described in any one of claims 1-7, characterized in that, Includes the following steps: Continuous fiber prepreg laying; A continuous fiber prepreg is cut to obtain a reinforcing unit corresponding to a tooth body. The reinforcing unit includes a first reinforcing unit containing a first layer and a second reinforcing unit containing a second layer. Multiple reinforcement units are circumferentially spliced ​​together to obtain an reinforcement layer; After the reinforcing layers are stacked, they are hot-pressed to obtain a continuous fiber reinforced body; Continuous fiber reinforcement is connected to the inner ring to obtain a pre-assembled structure; The pre-assembled structure is injection-compression molded to obtain a continuous fiber-reinforced composite gear.

9. The preparation method according to claim 8, characterized in that, A splicing interface is provided between adjacent reinforcement units. The splicing interface is provided with: an overlapping area, a stepped splicing area, a miter splicing area, or a complementary splicing area. Adjacent reinforcement units partially overlap at the splicing interface.

10. The preparation method according to claim 8, characterized in that, Injection compression molding methods include: After the pre-assembled structure is placed into the molding die, self-lubricating polymer melt is injected into the mold cavity of the molding die, and injection compression coating molding is performed to obtain a continuous fiber reinforced composite gear. The polymer melt comprises the following components by weight percentage: 80% polyetheretherketone; 10% polytetrafluoroethylene; 5% graphite; and 5% chopped carbon fiber.

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