Composite impact-resistant fork and preparation method thereof

Abstract

The present application belongs to the technical field of carrying robot forks, and discloses a composite impact-resistant fork and a preparation method thereof. A surface impact-resistant layer, an intermediate interface layer and a bottom rigid layer are sequentially arranged from one side to the other side. The surface impact-resistant layer is a composite structure of a carbon fiber two-dimensional woven structure and a thermoplastic resin matrix. The intermediate interface layer is a composite structure of an aramid honeycomb structure and a thermoplastic resin matrix. The bottom rigid layer comprises a main body and a plurality of buffer sheets. The main body is a composite structure of a high-strength carbon fiber three-dimensional woven structure and a thermosetting resin matrix. The plurality of buffer sheets are uniformly embedded on the side of the main body close to the intermediate interface layer. The fork with the structure has good impact resistance, rigidity, shock resistance and buffering performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of transport robot forks, and in particular relates to a composite impact-resistant fork and a preparation method thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the continuous advancement of technology, many tasks are gradually being replaced by robots, significantly reducing labor costs and improving efficiency. Handling robots feature high-speed, stable control technology. They achieve smooth handling through trajectory optimization, improved fork rigidity, and enhanced joint servo performance. Handling robots enable fully automated handling and transfer of goods. Their performance directly impacts production efficiency, thus significantly improving and optimizing the forks in handling robots.

[0004] Compared with ordinary forks, carbon fiber composite forks have the advantages of light weight, strong corrosion resistance, and high fatigue strength. However, forks are generally subjected to large impact and shear forces during use. General carbon fiber composite materials have a layered structure. Under these forces, the layered structure of carbon fiber composite materials is prone to delamination, and the fork as a whole is prone to deformation or even bending, affecting the overall service life of the fork. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a composite impact-resistant fork and a preparation method thereof.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] In a first aspect, the present invention provides a composite impact-resistant fork, which is provided with a surface impact-resistant layer, an intermediate interface layer and a bottom rigid layer in sequence from one side to the other side, wherein:

[0008] The surface impact-resistant layer is a composite structure of a carbon fiber two-dimensional woven structure and a thermoplastic resin matrix;

[0009] The middle interface layer adopts a composite structure of aramid honeycomb structure and thermoplastic resin matrix;

[0010] The bottom rigid layer includes a main body and a plurality of buffer sheets. The main body is a composite structure of a high-strength carbon fiber three-dimensional woven structure and a thermosetting resin matrix. The buffer sheets are evenly distributed in a matrix and pre-embedded on one side of the main body close to the middle interface layer, so that the buffer sheets are directly bonded and fixed to the middle interface layer.

[0011] The thickness of the buffer sheet is greater than or equal to 1 mm, and the thickness of the bottom rigid layer is at least twice the thickness of the buffer sheet.

[0012] In a second aspect, the application provides a method for manufacturing the composite impact-resistant fork, comprising the following steps:

[0013] milling and forming the aramid honeycomb and filling the thermoplastic resin;

[0014] respectively laying the thermoplastic adhesive film on the upper and lower surfaces of the aramid honeycomb filled with the thermoplastic resin;

[0015] Then, the carbon fiber two-dimensional woven structure prepreg and the carbon fiber three-dimensional woven structure prepreg are respectively laid on the upper and lower surfaces of the aramid honeycomb, and the buffer sheet is uniformly embedded in the side of the carbon fiber three-dimensional woven structure prepreg close to the aramid honeycomb;

[0016] After the laying is completed, hot pressing and curing are performed to form the same.

[0017] The application achieves the following beneficial effects through one or more embodiments:

[0018] The surface impact-resistant layer is a composite structure of the carbon fiber two-dimensional woven structure and the thermoplastic resin matrix. The carbon fiber two-dimensional woven structure isotropically strengthens the resin matrix and does not have a weak strengthening direction. Meanwhile, the strengthening structure is a two-dimensional woven structure, and the carbon fibers have strong interaction forces, so that the carbon fibers will not split under strong impact and have strong impact resistance.

[0019] The intermediate interface layer adopts a composite structure of the aramid honeycomb and the thermoplastic resin. This structure has strong shear resistance, can effectively improve the shear resistance of the fork, and especially can improve the bending strength of the fork. Meanwhile, this structure can significantly reduce the weight of the fork and enhance the specific strength of the fork.

[0020] The main body of the bottom rigid layer is a composite structure of the high-strength carbon fiber three-dimensional woven structure and the thermosetting resin matrix. This structure has strong rigidity, can effectively reduce the deformation of the fork during the forking process, and can provide strong support for the surface impact-resistant layer and the intermediate interface layer to effectively improve the use performance of the composite material fork.

[0021] The buffer sheet is uniformly embedded in the side of the bottom rigid layer close to the intermediate interface layer. The buffer sheet is used for energy absorption and can well buffer the impact force applied to the fork, reduce the instantaneous impact on the bottom rigid layer, improve the stress condition of the bottom rigid layer, and avoid the rupture of the bottom rigid layer under a large impact force. Meanwhile, the buffer sheet also has a damping performance, so that the forking process is more stable.

[0022] The thickness of the buffer sheet is greater than or equal to 1mm to ensure effective buffering. The thickness of the bottom rigid layer is limited so that the bottom rigid layer, excluding the thickness of the embedded buffer sheet, is still thick enough to effectively support the surface impact-resistant layer and the intermediate interface layer of the fork.

[0023] If a buffer sheet is embedded within the bottom rigid layer and bonded to the intermediate interface layer via a portion of the bottom rigid layer, this portion of the bottom rigid layer must first deform to transfer force to the buffer sheet, allowing the buffer sheet to function effectively. However, this deformation of the bottom rigid layer will cause other parts of the bottom rigid layer to deform as well, weakening the buffer sheet's effectiveness. Therefore, the buffer sheet is designed to be directly bonded to the intermediate interface layer. When cargo is placed on the fork, force is transferred directly to the buffer sheet through the surface impact-resistant layer and the intermediate interface layer, allowing the buffer sheet to function effectively and reducing deformation of the bottom rigid layer.

[0024] During the hot pressing process, a small amount of resin from the prepreg on both sides of the aramid honeycomb enters the honeycomb and forms a composite with it, forming a single unit with the impact-resistant surface layer, the middle interface layer, and the bottom rigid layer. This prevents delamination during use and further improves the fork's rigidity and impact resistance. This composite material also exhibits excellent corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0026] Figure 1 This is a schematic diagram of the overall structure of the composite impact-resistant plate structure according to an embodiment of the present invention;

[0027] Figure 2 This is a plan view of the bottom rigid layer of the composite impact-resistant plate structure according to an embodiment of the present invention.

[0028] Among them, 1. Surface impact-resistant layer; 2. Middle interface layer; 3. Bottom rigid layer; 4. Buffer sheet. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0030] In a first aspect, the present invention provides a composite impact-resistant fork, which is provided with a surface impact-resistant layer, an intermediate interface layer and a bottom rigid layer in sequence from one side to the other side, wherein:

[0031] The surface impact-resistant layer is a composite structure of a carbon fiber two-dimensional woven structure and a thermoplastic resin matrix;

[0032] The middle interface layer adopts a composite structure of aramid honeycomb structure and thermoplastic resin matrix;

[0033] The bottom rigid layer includes a main body and a plurality of buffer sheets. The main body is a composite structure of a high-strength carbon fiber three-dimensional woven structure and a thermosetting resin matrix. The buffer sheets are evenly distributed in a matrix and pre-embedded on one side of the main body close to the middle interface layer, so that the buffer sheets are directly bonded and fixed to the middle interface layer.

[0034] The thickness of the buffer sheet is greater than or equal to 1 mm, and the thickness of the bottom rigid layer is at least twice the thickness of the buffer sheet.

[0035] Carbon fiber is a high-strength, high-modulus specialty fiber with excellent mechanical properties, including high strength and modulus. It also boasts advantages such as light weight, stable chemical composition, and excellent high-temperature resistance. Compared to conventional steel forks, carbon fiber composite forks offer advantages such as light weight, high strength-to-weight ratio, strong corrosion resistance, and high fatigue strength. The aramid honeycomb core layer in the sandwich structure primarily bears shear stress, imparting high flexural rigidity to the structure.

[0036] The plate adopts a multi-layer structure, which effectively improves the rigidity, impact resistance and friction resistance of the fork.

[0037] In some embodiments, the buffer sheet is a chopped carbon fiber reinforced silicone rubber composite material.

[0038] The embedded buffer sheet in the rigid layer is composed of silicone rubber doped with chopped carbon fiber, which not only has good high strength and high specific stiffness, but also has excellent shock absorption and anti-vibration buffering effect.

[0039] Preferably, the mass percentage of the silicone rubber in the buffer sheet is 30-50%, and the length of the chopped carbon fibers is 2-5 mm.

[0040] In some embodiments, the two-dimensional planar woven structure of the surface impact-resistant layer is selected from plain, twill or satin woven structures, and the resin content is 30%-60%.

[0041] Preferably, the carbon fiber of the surface impact-resistant layer is high-strength carbon fiber selected from T300, T700, T800 or T1000.

[0042] Preferably, the thermoplastic resin of the surface impact-resistant layer is selected from polyethylene, polypropylene, polyvinyl chloride or polystyrene.

[0043] Preferably, the thickness of the surface impact-resistant layer is 2-4 mm.

[0044] In some embodiments, the thickness of the intermediate interface layer is 3-5 mm.

[0045] Preferably, the resin content of the intermediate interface layer is 30%-60%.

[0046] Aramid honeycomb is typically manufactured using a stretching and expansion method. The production process consists of nine steps: gluing, laminating, pressing, cutting, stretching, shaping, dipping, curing, and slicing. The thermoplastic resin used for the impact-resistant surface layer can be any of the types mentioned above, but is not limited to these.

[0047] In some embodiments, the thickness of the bottom rigid layer is 3-5 mm, and the thickness of the buffer sheet is 1-2 mm.

[0048] Preferably, the difference in thickness between the bottom rigid layer and the buffer sheet is at least 2 mm, so as to ensure the rigidity of the bottom rigid layer on the side where the buffer sheet is not embedded, thereby providing sufficient support.

[0049] Preferably, the resin content of the bottom rigid layer is 30-60%.

[0050] Preferably, the three-dimensional woven structure of the bottom rigid layer is a three-dimensional four-directional, three-dimensional five-directional, three-dimensional six-directional or three-dimensional seven-directional woven structure;

[0051] The thermosetting resin is selected from epoxy resin, phenolic resin, unsaturated polyester resin or urea-formaldehyde resin.

[0052] In a second aspect, the present invention provides a method for preparing the composite impact-resistant fork, comprising the following steps:

[0053] Aramid honeycomb milled and filled with thermoplastic resin;

[0054] Thermoplastic films are laid on the upper and lower surfaces of the aramid honeycomb respectively;

[0055] Then, a carbon fiber two-dimensional woven structure prepreg and a carbon fiber three-dimensional woven structure prepreg are laid on the upper and lower surfaces of the aramid honeycomb respectively, and a buffer sheet is evenly pre-embedded in the carbon fiber three-dimensional woven structure prepreg on the side close to the aramid honeycomb;

[0056] After laying, hot pressing and curing are carried out to obtain the product.

[0057] In some embodiments, the thermoplastic film is made of polyetherimide (PEI), polyetherketone (PEK), polysulfone (PSF) or polyethersulfone (PES).

[0058] In some embodiments, a method for preparing a carbon fiber two-dimensional woven structure prepreg is as follows: placing a thermoplastic film and a carbon fiber cloth laminate on a preheated press, and hot pressing to obtain;

[0059] The hot pressing temperature is 120-150°C, the pressure is 0.5-2MPa, and the hot pressing time is 20-60min. After the hot pressing is completed, the heating is stopped and maintained for 40-60min.

[0060] Preferably, ultrafine thermoplastic bonding powder is sprayed between adjacent carbon fiber cloths.

[0061] More preferably, the ultrafine thermoplastic adhesive powder is selected from polyamide powder, polyethylene powder or polyurethane powder, and the powder particle size can be flexibly selected within the range of 200 to 2000 mesh.

[0062] In some embodiments, the temperature of the hot pressing curing molding is 110-130° C., and the molding pressure is 0.1-0.5 MPa.

[0063] The compression molding process involves placing a laminated sheet made of prepreg cloth in a specific metal mold, and then heating and pressurizing it to solidify it. The compression molding process involves first cutting the carbon fiber sheet according to the product size, cleaning the specific structural mold, applying a release agent, placing the carbon fiber sheet, and closing the mold. When screwing in the screws, apply lubricant to ensure smooth mold opening. Place the finished carbon fiber product mold on a preheated hot press and perform 3 to 4 depressurization cycles with an interval of 10 to 20 seconds. Set the press temperature to 130 to 180°C, the pressure to 2 to 10 MPa, and the pressurization time to 30 to 90 minutes. Then stop heating and maintain for 30 to 60 minutes. Demolding is performed after the mold cools down.

[0064] The present invention will be further described below with reference to the embodiments.

[0065] Example 1

[0066] like Figure 1 As shown, the surface impact-resistant layer 1 is a 3mm thick, 40% resin composite of T700 high-strength carbon fiber in a two-dimensional twill weave. Polyamide powder with a particle size of 1000 mesh is used for bonding during hot pressing, and polyetherimide film is used as the thermoplastic adhesive film. Both hot pressing and compression molding are performed at a press temperature of 150°C and a pressure of 6 MPa. Before pressing, the pressure is released three times, with intervals of 10 seconds. The pressing time is 40 minutes, followed by a 35-minute hold after heating.

[0067] The middle interface layer 2 is a honeycomb structure, which is composed of an aramid honeycomb structure and a polypropylene resin matrix, with a resin content of 60% and a thickness of 5 mm.

[0068] The bottom rigid layer 3 is constructed of T1000 high-strength carbon fiber using a three-dimensional, seven-way braid structure and epoxy resin impregnation. The buffer sheet 4 is made of silicone rubber doped with chopped carbon fiber, with a silicone rubber content of 30%. The chopped carbon fiber is 2mm long and the buffer sheet is 2mm thick. The buffer sheets are evenly distributed in a matrix within the bottom rigid layer. The bottom rigid layer is 5mm thick and has a resin content of 40%.

[0069] The three laminated parts are cured in an autoclave at a curing temperature of 120° C. and a molding pressure of 0.3 MPa. The overall resin matrix content of the structural plate is 45% and the thickness is 13 mm.

[0070] Example 2

[0071] The impact-resistant surface layer is a 2mm thick, 50% resin composite of T800 high-strength carbon fiber in a two-dimensional plain weave. Polypropylene powder with a particle size of 1000 mesh is used for hot pressing, and the thermoplastic film is a polysulfone film. Both hot pressing and compression molding are performed at a press temperature of 180°C and a pressure of 7 MPa. Before pressing, the pressure is released three times, with intervals of 10 seconds. The pressing time is 80 minutes, followed by a 40-minute hold after heating.

[0072] The middle honeycomb layer is composed of an aramid honeycomb structure and a polyethylene resin matrix, with a resin content of 50% and a thickness of 4 mm.

[0073] The bottom rigid layer is constructed of T300 high-strength carbon fiber in a three-dimensional, four-directional braided structure impregnated with phenolic resin. The buffer sheet is made of silicone rubber doped with chopped carbon fiber, with a silicone rubber content of 50%. The chopped carbon fiber is 4mm long and the buffer sheet is 2mm thick. The buffer sheets are evenly distributed in a matrix within the bottom rigid layer. The bottom rigid layer is 4mm thick and has a resin content of 50%.

[0074] The three laminated parts are cured in an autoclave at a curing temperature of 120° C. and a molding pressure of 0.3 MPa. The overall resin matrix content of the structural plate is 50% and the thickness is 10 mm.

[0075] Example 3

[0076] The impact-resistant surface layer is constructed from T700 high-strength carbon fiber in a two-dimensional satin weave, laminated with polyvinyl chloride resin. The thickness is 3mm and the resin content is 60%. Hot pressing uses 800-mesh polyamide powder for bonding, and the thermoplastic film is polyetherimide film. Both hot pressing and compression molding are performed at a press temperature of 150°C and a pressure of 6 MPa. Before pressing, the pressure is released three times, with intervals of 10 seconds. The pressing time is 90 minutes, followed by a 35-minute hold after heating.

[0077] The middle interface layer is a honeycomb structure, which is composed of an aramid honeycomb structure and a polyvinyl chloride resin matrix, with a resin content of 60% and a thickness of 5 mm.

[0078] The bottom rigid layer is constructed from T1000 high-strength carbon fiber using a three-dimensional, five-directional braid structure and impregnated with urea-formaldehyde resin. The buffer sheet is made of silicone rubber doped with chopped carbon fiber, with a silicone rubber content of 40%. The chopped carbon fiber is 5mm long and the buffer sheet is 1mm thick. The buffer sheets are evenly distributed in a matrix within the bottom rigid layer. The bottom rigid layer is 4mm thick and has a resin content of 55%.

[0079] The three laminated parts are cured in an autoclave at a curing temperature of 120° C. and a molding pressure of 0.3 MPa. The overall resin matrix content of the structural plate is 58% and the thickness is 12 mm.

[0080] Example 4

[0081] The impact-resistant surface layer is constructed from T300 high-strength carbon fiber in a two-dimensional twill weave, laminated with polyethylene resin. The thickness is 3mm and the resin content is 50%. Hot pressing uses 500-mesh polyamide powder for bonding, and the thermoplastic film is polyetherimide film. Both hot pressing and compression molding are performed at a press temperature of 130°C and a pressure of 5 MPa. Before pressing, the pressure is released three times, with intervals of 10 seconds. The pressing time is 50 minutes, followed by a 60-minute hold after heating.

[0082] The intermediate interface layer is a honeycomb structure, constructed from an aramid honeycomb structure and a polypropylene resin matrix with a resin content of 30% and a thickness of 4mm. The bottom rigid layer utilizes T1000 high-strength carbon fiber in a three-dimensional, six-directional braided structure impregnated with epoxy resin. The buffer sheet is composed of silicone rubber doped with chopped carbon fiber with a silicone rubber content of 30%. The chopped carbon fiber is 2mm long and the buffer sheet is 2mm thick. The buffer sheets are evenly distributed in a matrix within the bottom rigid layer. The bottom rigid layer is 4mm thick and has a resin content of 40%.

[0083] The three laminated parts are cured in an autoclave at a curing temperature of 120° C. and a molding pressure of 0.3 MPa. The overall resin matrix content of the structural plate is 40% and the thickness is 11 mm.

[0084] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A composite impact-resistant fork, characterized by: The surface impact-resistant layer, the middle interface layer and the bottom rigid layer are sequentially arranged from one side to the other side, wherein: The surface impact-resistant layer is a composite structure of a carbon fiber two-dimensional woven structure and a thermoplastic resin matrix; The middle interface layer adopts a composite structure of aramid honeycomb structure and thermoplastic resin matrix; The bottom rigid layer includes a main body and a plurality of buffer sheets. The main body is a composite structure of a high-strength carbon fiber three-dimensional woven structure and a thermosetting resin matrix. The buffer sheets are evenly distributed in a matrix and pre-embedded on one side of the main body close to the middle interface layer, so that the buffer sheets are directly bonded and fixed to the middle interface layer. The thickness of the buffer sheet is greater than or equal to 1mm, and the thickness of the bottom rigid layer is at least twice the thickness of the buffer sheet; The thickness of the surface impact-resistant layer is 2-4 mm; the thickness of the middle interface layer is 3-5 mm.

2. The composite impact-resistant fork according to claim 1, characterized in that: The buffer sheet is a short-cut carbon fiber reinforced silicone rubber composite material; the mass percentage of silicone rubber in the buffer sheet is 30-50%, and the length of the short-cut carbon fiber is 2-5 mm.

3. The composite impact-resistant fork according to claim 1, characterized in that: The two-dimensional planar weaving structure of the surface impact-resistant layer is selected from plain, twill or satin weaving structure; the carbon fiber of the surface impact-resistant layer is high-strength carbon fiber selected from T300, T700, T800 or T1000.

4. The composite impact-resistant fork according to claim 1, characterized in that: The thickness of the bottom rigid layer is 3-5 mm, and the thickness of the buffer sheet is 1-2 mm.

5. The composite impact-resistant fork according to claim 1, characterized in that: The difference in thickness between the bottom rigid layer and the buffer sheet is at least 2 mm.

6. The composite impact-resistant fork according to claim 1, characterized in that: The resin content of the surface impact-resistant layer is 30%-60%, the resin content of the middle interface layer is 30%-60%, and the resin content of the bottom rigid layer is 30%-60%.

7. The method for preparing the composite impact-resistant fork according to any one of claims 1 to 6, characterized in that: The steps include: Aramid honeycomb milled and filled with thermoplastic resin; Laying thermoplastic films on the upper and lower surfaces of the aramid honeycomb filled with thermoplastic resin respectively; Then, a carbon fiber two-dimensional woven structure prepreg and a carbon fiber three-dimensional woven structure prepreg are laid on the upper and lower surfaces of the aramid honeycomb respectively, and a buffer sheet is evenly pre-embedded in the carbon fiber three-dimensional woven structure prepreg on the side close to the aramid honeycomb; After laying, hot pressing and curing are carried out to obtain the product.

8. The method for preparing a composite impact-resistant fork according to claim 7, characterized in that: The material of the thermoplastic film is polyetherimide, polyetherketone, polysulfone or polyethersulfone.

9. The method for preparing a composite impact-resistant fork according to claim 7, characterized in that: The preparation method of the carbon fiber two-dimensional woven structure prepreg is as follows: placing a thermoplastic film and a carbon fiber cloth laminate on a preheated press, and hot pressing to obtain; The hot pressing temperature is 120-150°C, the pressure is 0.5-2MPa, and the hot pressing time is 20-60min. After the hot pressing is completed, the heating is stopped and maintained for 40-60min.

10. The method for preparing a composite impact-resistant fork according to claim 7, characterized in that: Ultrafine thermoplastic bonding powder is sprayed between adjacent carbon fiber cloths; the ultrafine thermoplastic bonding powder is selected from polyamide powder, polyethylene powder or polyurethane powder.

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