Carbon fiber foam leaf spring and manufacturing method thereof

Abstract

The present invention relates to a carbon fiber foam leaf spring and a manufacturing method thereof, comprising an upper carbon fiber layer, a sheet foam material layer and a lower carbon fiber layer, wherein the upper and lower carbon fiber layers are bonded together, the sheet foam material layer is located between the upper and lower carbon fiber layers, the upper carbon fiber layer comprises an upper carbon fiber ply, and a plurality of upper carbon fiber plies are stacked in sequence, the sheet foam material layer comprises a foam ply, and a plurality of foam plies are stacked in sequence, the lower carbon fiber layer comprises a lower carbon fiber ply, and a plurality of lower carbon fiber plies are stacked in sequence, the layers are closely attached to each other, and the foam material layer and the carbon fiber layer are formed at one time. The present invention simplifies the manufacturing process of the product, reduces mold investment, improves efficiency, reduces weight and cost; improves the rigidity, strength and impact resistance of the product, and achieves a shock-absorbing effect.

Description

Technical Field

[0001] The invention relates to the technical field of leaf spring processing, and in particular to a carbon fiber foam leaf spring and a manufacturing method thereof. Background Art

[0002] At present, carbon fiber foam leaf springs are a kind of lightweight and high-strength structure in the field of composite materials. According to the overall structure of leaf spring shape, its manufacturing process on the market is a foam core material segmented molding process, and then the main body and foam are combined into one by later molding. Its disadvantages are as follows: 1. The initial investment cost is high. In order to complete the foaming molding process, a molding mold must be made first. Based on P20 steel, it is estimated that the investment cost is doubled. Under the conditions of fierce market competition, there is no competitive advantage. 2. The process flow is long and the efficiency is low: the traditional foam core material process is to first mold the foam material, then coat the carbon fiber prepreg on the foam core material, and then mold it again. The foam molding process is added, the process is increased, the molding time is extended, the overall efficiency is reduced, and the energy consumption is increased; 3. In production, no matter how the surface of the foam core material is treated, the carbon fiber prepreg and the foam core material are molded by the molding process, and then sprayed and baked. The solvent in the paint penetrates between the carbon fiber and the foam core material, which will cause the carbon fiber and the foam core material to delaminate and blister. Summary of the invention

[0003] In order to solve the problems of the prior art, the present invention provides a carbon fiber foam leaf spring and a manufacturing method thereof which can be highly efficient, reduce molding time, ensure high efficiency and stable quality of product production, break through the bottleneck of mass production, and realize engineering application.

[0004] The specific technical scheme is as follows: a carbon fiber foam leaf spring, comprising an upper carbon fiber layer, a sheet foaming material layer and a lower carbon fiber layer, the upper and lower carbon fiber layers are bonded together, the sheet foaming material layer is located between the upper and lower carbon fiber layers, the upper carbon fiber layer comprises an upper carbon fiber ply, and several upper carbon fiber plies are stacked in sequence, the sheet foaming material layer comprises a foaming ply, and several foaming plies are stacked in sequence, the lower carbon fiber layer comprises a lower carbon fiber ply, and several lower carbon fiber plies are stacked in sequence, the layers are closely attached, and the foaming material layer and the carbon fiber layer are formed at one time.

[0005] In some embodiments, the upper carbon fiber ply, the foamed ply and the lower carbon fiber ply are prepreg laid up in sequence from inside to outside according to ±45° / 0° / ±45° / 90° / 0° / foaming / foaming / foaming / 0° / 90° / ±45° / 0° / ±45°, and vacuum is drawn once each time a layer is laid.

[0006] A method for manufacturing a carbon fiber foam leaf spring comprises the following steps:

[0007] S1: prepreg processing, making prepreg;

[0008] S2: Cutting: Cut the prepreg into the required size according to the product size requirements;

[0009] S3: Preforming, making the upper layer of carbon fiber, the middle layer of foam material, and the lower layer of carbon fiber ply prepreg. Each time a layer is pasted, vacuum is drawn to ensure that the layers are closely attached to each other;

[0010] S4: Molding: first, the upper mold and the lower mold of the mold are heated to a preset temperature, then the preformed product is placed in the mold for preheating, and the mold is closed, and there is a gap between the product and the mold after the mold is closed;

[0011] S5: Post-processing: the semi-finished product obtained after molding is cut and polished according to the size and shape used to obtain the finished product.

[0012] In some embodiments, in step S1, ±45° / 0° / 90 yarn material is used, and the prepregs are overlapped and then subjected to exhaust treatment by a drum vacuum machine.

[0013] In some embodiments, a foam material with a thickness of 0.5 mm and Toray T700 UD carbon fiber prepreg are selected to make the main structure raw materials.

[0014] In some embodiments, in step S1, the preparation method of carbon fiber prepreg is: loading carbon fiber into a creel, loading epoxy resin film into a machine in upper and lower rolls, heating the prepreg machine roller and then impregnating it to obtain carbon fiber prepreg, wherein the epoxy resin is placed in an oven at 70°C and heated to melt into a liquid state according to the required amount, then poured into a coating machine for coating, and the release paper is loaded on the coating machine fixed frame for coating to make a resin film.

[0015] In some embodiments, the epoxy resin is selected to have a viscosity of 3000-4000 CPS / 70±1 and is highly transparent and free of white spots.

[0016] In some embodiments, in step S3, the prepreg is layered from inside to outside in the order of ±45° / O° / ±45° / 90° / 0° / foaming / foaming / foaming / 0° / 90° / ±45° / 0° / ±45°, and each layer is vacuumed to ensure that the layers are tightly fitted to each other.

[0017] In some embodiments, in step S3, the outer diameter of the preformed product is smaller than the outer diameter of the finished product.

[0018] In some embodiments, in step S4, the preset temperature of the mold is 130-140°C, the preheating time is 15S, the molding pressure is 60T, the thickness of the foaming material is 0.5mm, and the foaming ratio is 8.5-14.5 times.

[0019] The technical effect of the present invention is as follows: In this embodiment, the sheet foaming and the carbon fiber prepreg are formed at one time, the forming process is simpler, and it is more conducive to mass production; the internal pressure formed by the expansion of the foaming when heated makes the foaming and the carbon fiber prepreg fit more closely, and no secondary forming is required, which meets the requirements of lightness and strength, ensures the stability of quality, and reduces the defective rate. Through the principle of internal pressure generated by thermal expansion of foaming, the preformed product is small when the mold is closed to avoid the phenomenon of yarn clamping, and the overlap of the main yarn ensures the strength of the product, meeting the requirements for product strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a carbon fiber foam leaf spring according to an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of a carbon fiber foam leaf spring according to an embodiment of the present invention when being processed in a mold. DETAILED DESCRIPTION

[0022] The essential features and advantages of the present invention are further described below in conjunction with examples, but the present invention is not limited to the listed embodiments.

[0023] [Example 1]

[0024] A carbon fiber foam leaf spring of this embodiment includes an upper carbon fiber layer 5, a sheet foam material layer 6 and a lower carbon fiber layer 7. The upper and lower carbon fiber layers are bonded together. The sheet foam material layer 6 is located between the upper and lower carbon fiber layers. The upper carbon fiber layer 5 includes an upper carbon fiber ply, and a plurality of upper carbon fiber plies are stacked in sequence. The sheet foam material layer 6 includes a foam ply, and a plurality of foam plies are stacked in sequence. The lower carbon fiber layer 7 includes a lower carbon fiber ply, and a plurality of lower carbon fiber plies are stacked in sequence. The layers are closely attached to each other, and the foam material layer and the carbon fiber layer are formed at one time. In the above technical scheme, the sheet foam material is used to bond the upper and lower carbon fiber layers and serve as a reinforcing layer to improve the rigidity, strength and impact resistance of the product and achieve a shock-absorbing effect.

[0025] Furthermore, the upper carbon fiber layer, the foamed layer and the lower carbon fiber layer are laid out from the inside to the outside in the order of ±45° / 0° / ±45° / 90° / 0° / foamed / foamed / foamed / 0° / 90° / ±45° / 0° / ±45° prepreg, and each layer is vacuumed once to ensure that the layers are closely attached to each other and improve the structural strength of the product.

[0026] [Example 2]

[0027] The manufacturing method of the carbon fiber foam leaf spring of this embodiment does not need to form the foam separately, but only needs to lay the carbon fiber prepreg layer by layer according to the structure, and put it into the mold at one time after the preforming is completed, and heat and pressurize it by using the internal pressure principle generated by the thermal expansion of the foam. The steps are as follows:

[0028] 1. Prepreg processing: ±45° / 0° / 90 yarn is required. ±45° / 0° / 90° yarn refers to fiber yarn materials woven or arranged at different angles. It is a conventional term in this field and is usually used to describe the fiber orientation in textiles or composite materials. The prepregs need to be overlapped and then vented by a drum vacuum machine; 2. Yarn cutting: According to the product size requirements, the prepreg is accurately cut into the required size with an automatic yarn cutter; 3. Preforming: Prepreg is laid according to the upper carbon fiber layer, the middle layer foaming layer, and the lower carbon fiber layer. Each time a layer is pasted, it is vacuumed once to ensure that the layers are tightly fitted. The outer diameter of the preformed product is smaller than the outer diameter of the finished product. Specifically, the size is determined according to the product thickness and the number of foaming layers. 4. Molding: First, heat the upper mold 1 and the lower mold 4 to 130-140℃, then put the product 3 into the mold for preheating for 15s, and then close the mold. After closing the mold, the single-side gap 2 between the product and the mold is determined by the product thickness and the number of foaming layers. The mold molding pressure is 60T, and the pressing molding time is 60min. The molding pressure and time can be appropriately adjusted according to the product thickness and material selection. 5. Post-processing: The semi-finished product is cut and polished according to the size and shape used to obtain the finished product.

[0029] In the above technical scheme, this embodiment forms the sheet foaming and carbon fiber prepreg at the same time, which makes the forming process simpler and more conducive to mass production; the internal pressure formed by the expansion of the foaming when heated is used to make the foaming and the carbon fiber prepreg fit more closely, and no secondary forming is required, which meets the requirements of lightness and strength, ensures the stability of quality, and reduces the defective rate. Through the principle of internal pressure generated by thermal expansion of foaming, the preformed product is small when the mold is closed to avoid the phenomenon of yarn clamping, and the overlap of the main yarn ensures the strength of the product, meeting the requirements for product strength. After the carbon fiber foam leaf spring manufactured in this embodiment passed the flaw detection and trial assembly, all indicators met the standard requirements.

[0030] The manufacturing method of the carbon fiber foam leaf spring is further explained below in conjunction with specific products.

[0031] The product of this embodiment is 10mm thick, and its production process includes the following steps: the sheet is foamed and coated inside the carbon fiber prepreg, so that it is put into the mold together with the carbon fiber preform, and the internal pressure generated by the thermal expansion of the foaming is used to realize the product molding process, which is simple to operate and is conducive to mass production. The specific steps are as follows:

[0032] 1) Carbon fiber foam leaf spring overmolding, using sheet foam core material and carbon fiber prepreg for one-time molding;

[0033] 2) Production of special-shaped sheets and yarns: First, use CAD software to produce the expansion diagram of foaming and yarns as needed to facilitate the engraving of materials; this embodiment uses a foaming material with a thickness of 0.5 mm and Toray T700 UD carbon fiber prepreg to produce the main structural raw materials;

[0034] 3) The main body is formed, and the prepreg is laid from the inside to the outside in the order of (upper carbon fiber layer 5) ±45° / 0° / ±45° / 90° / 0° / foaming / foaming / foaming (foaming material middle layer 6) / 0° / 90° / ±45° / 0° / ±45° (lower carbon fiber layer 7). The numbers and symbols here represent the orientation angles of the fibers or material layers, which are conventional terms in the art. ±45° ply: The ±45° here means that the fiber layers are arranged at a 45-degree angle relative to the reference direction (usually the length or width of the board). ±45° ply provides good shear modulus and shear strength, while also increasing the toughness and damage tolerance of the material. Because at this angle, the fibers can effectively bear the loads applied in two main directions, which makes the material have more balanced performance in all directions. 0° ply means that the fiber layers are arranged parallel to the length direction of the board (usually the running direction of the machine). This plying method provides the material with maximum axial strength and stiffness. Each time a layer is pasted, vacuum is drawn to ensure that the layers fit tightly together. The outer diameter of the preformed product is 3mm-4mm smaller than the outer diameter of the finished product.

[0035] 4) First, the upper mold 1 and the lower mold 4 are heated to 130-140°C, and then the product 3 is placed in the mold for preheating for 15 seconds, and then the mold is closed. After the mold is closed, the single-side gap 2 between the product and the mold is about 2mm, the mold molding pressure is 60T, and the pressing molding time is 60min.

[0036] 5) Post-processing: The semi-finished product is cut, polished and sprayed according to the size and shape used to obtain the finished product.

[0037] The preformed outer diameter of the main body is 4-5 mm smaller than the outer diameter of the finished product. The product molding process is achieved by utilizing the internal pressure generated by the thermal expansion of the foam, thereby avoiding yarn clamping when the upper and lower molds are closed, meeting the product's strength requirements, and is not prone to delamination, blistering and other undesirable phenomena. It also has a smooth appearance and good quality.

[0038] The carbon fiber in this embodiment is UD Toray T700 carbon fiber, which has a tensile strength of 3000MPa, and the surface is specially treated, so that it can penetrate better when pre-impregnated with epoxy resin, thereby enhancing the strength of the product. The epoxy resin in this embodiment is a high-transparency epoxy resin with a viscosity of 3000-4000CPS / 70±1 without white spots, which has better fluidity, viscosity and operability. The molded product has excellent mechanical properties, and the glass transition temperature is 130-140°C.

[0039] In order to obtain a better molding effect and improve molding efficiency, the heat treatment state of the present embodiment is maintained at a temperature of 130-140°C and a molding pressure of 60T during the foaming integrated molding. In order to meet the conditions during the molding heat treatment, the foaming thickness is selected to be 0.5mm. The foaming ratio is 8.5-14.5 times. The resin glue in the carbon fiber prepreg is selected to be 130-140°C epoxy resin glue.

[0040] Furthermore, the preparation method of carbon fiber prepreg is as follows: carbon fiber is loaded into a creel, the obtained epoxy resin film is loaded into a machine table in upper and lower rolls, and the prepreg machine roller is heated and impregnated to obtain carbon fiber prepreg. Among them, the epoxy resin is put into an oven at 70°C and heated to melt into a liquid state according to the required amount, and then poured into a coating machine for coating, and the release paper is loaded into the coating machine fixed frame for coating to form a resin film. In order to meet the conditions during the molding heat treatment, the sheet body foaming adopts a woven material with added glass fiber, which has strong operability.

[0041] It should be pointed out that the above preferred embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A carbon fiber foam leaf spring, characterized in that: It includes an upper carbon fiber layer, a sheet foaming material layer and a lower carbon fiber layer, the upper and lower carbon fiber layers are bonded together, the sheet foaming material layer is located between the upper and lower carbon fiber layers, the upper carbon fiber layer includes an upper carbon fiber ply, and several upper carbon fiber plies are stacked in sequence, the sheet foaming material layer includes a foaming ply, and several foaming plies are stacked in sequence, the lower carbon fiber layer includes a lower carbon fiber ply, and several lower carbon fiber plies are stacked in sequence, the layers are closely attached, and the foaming material layer and the carbon fiber layer are formed at one time.

2. The carbon fiber foam leaf spring according to claim 1, characterized in that: The upper carbon fiber ply, the foamed ply and the lower carbon fiber ply are laid with prepreg from the inside to the outside in the order of ±45° / 0° / ±45° / 90° / 0° / foaming / foaming / foaming / 0° / 90° / ±45° / 0° / ±45°, and the vacuum is drawn once for each layer.

3. A method for manufacturing a carbon fiber foam leaf spring, characterized in that: The following steps are involved: S1: prepreg processing, making prepreg; S2: Cutting: Cut the prepreg into the required size according to the product size requirements; S3: Preforming, making the upper layer of carbon fiber, the middle layer of foam material, and the lower layer of carbon fiber ply prepreg. Each time a layer is pasted, vacuum is drawn to ensure that the layers are closely attached to each other; S4: Molding: first, the upper mold and the lower mold of the mold are heated to a preset temperature, then the preformed product is placed in the mold for preheating, and the mold is closed, and there is a gap between the product and the mold after the mold is closed; S5: Post-processing: the semi-finished product obtained after molding is cut and polished according to the size and shape used to obtain the finished product.

4. The method for manufacturing a carbon fiber foam leaf spring according to claim 3, characterized in that: In the step S1, ±45° / 0° / 90 yarn material is used, and the prepregs are overlapped and then subjected to exhaust treatment by a roller vacuum machine.

5. The method for manufacturing a carbon fiber foam leaf spring according to claim 4, characterized in that: The main structural raw materials are made of 0.5mm thick foam material and Toray T700 UD carbon fiber prepreg.

6. The method for manufacturing a carbon fiber foam leaf spring according to claim 5, characterized in that: In step S1, the preparation method of carbon fiber prepreg is: carbon fiber is loaded into a creel, epoxy resin film is loaded into a machine table in upper and lower rolls, the prepreg machine roller is heated and impregnated to obtain carbon fiber prepreg, wherein the epoxy resin is put into an oven at 70°C and heated to melt into a liquid state according to the required amount, then poured into a coating machine for coating, and the release paper is loaded on the coating machine fixed frame for coating to make a resin film.

7. The method for manufacturing a carbon fiber foam leaf spring according to claim 6, characterized in that: The epoxy resin is selected with a viscosity of 3000-4000C PS / 70±1, high transparency and no white spots.

8. The method for manufacturing a carbon fiber foam leaf spring according to claim 3, characterized in that: In step S3, the prepreg is laid from the inside to the outside in the order of ±45° / 0° / ±45° / 90° / 0° / foaming / foaming / foaming / 0° / 90° / ±45° / 0° / ±45°, and each layer is vacuumed to ensure that the layers are tightly fitted.

9. The method for manufacturing a carbon fiber foam leaf spring according to claim 8, characterized in that: In step S3, the outer diameter of the preformed product is smaller than the outer diameter of the finished product.

10. The method for manufacturing a carbon fiber foam leaf spring according to claim 3, characterized in that: In step S4, the preset temperature of the mold is 130-140°C, the preheating time is 15S, the molding pressure is 60T, the thickness of the foaming material is 0.5mm, and the foaming ratio is 8.5-14.5 times.

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