阅读说明：本技术 基于预浸料成型的复合材料板簧本体的制备方法 (Preparation method of composite material plate spring body based on prepreg molding ) 是由 董轩诚 于 2021-08-16 设计创作，主要内容包括：本申请提供了一种基于预浸料成型的复合材料板簧本体的制备方法,该包括：将与复合材料板簧本体形状相同的预浸料铺设在模具的模腔内,以得到预成型板簧；铺设过程中,每铺设至少一层预浸料,在该至少一层预浸料的表面铺设一层纤维毡,并通过带有倒钩的针头,以拱形的形式将该一层纤维毡中的纤维段的两端嵌入到该至少一层预浸料中；封闭该模具并注入树脂材料；通过加压以及加热的方式固化该预成型板簧,以得到复合材料板簧本体。本申请提供的方法能够在控制设备研发成本和时间成本的基础上,生产出满足性能要求的板簧。(The application provides a preparation method of a composite plate spring body based on prepreg molding, which comprises the following steps: laying a prepreg with the same shape as the composite plate spring body in a die cavity of a die to obtain a preformed plate spring; in the laying process, when at least one layer of prepreg is laid, a layer of fiber felt is laid on the surface of the at least one layer of prepreg, and two ends of a fiber segment in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a barbed needle head; closing the mold and injecting a resin material; the preformed leaf spring is cured by means of pressure and heat to obtain a composite leaf spring body. The method provided by the application can be used for producing the plate spring meeting the performance requirement on the basis of controlling the research and development cost and the time cost of the equipment.)

1. A preparation method of a composite plate spring body based on prepreg molding is characterized by comprising the following steps:

laying a prepreg with the same shape as the composite plate spring body in a die cavity of a die to obtain a preformed plate spring; in the laying process, when at least one layer of prepreg is laid, a layer of fiber felt is laid on the surface of the at least one layer of prepreg, and two ends of a fiber segment in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a needle head with a barb;

closing the mold and injecting a resin material;

and curing the preformed plate spring by pressurizing and heating to obtain the composite plate spring body.

2. The method of claim 1, wherein for each layer of fiber mat in the pre-formed leaf spring, the length of the fiber segment is determined according to the thickness of the at least one layer of prepreg.

3. The method of claim 2, wherein said at least one layer of prepreg has a thickness of N; wherein the length of the fiber segment is greater than or equal to 2N + L + P, wherein L is proportional to the barb size, P is the offset, and N, L, P are all values greater than 0.

4. The method according to claim 1, wherein the length of the fiber length is proportional to the total thickness of the prepreg that has been laid in the mould for each layer of fiber mat in the pre-formed leaf spring.

5. The method according to claim 1, wherein at least one row of needles having the same size as the mold cavity is provided along a first direction of the preformed plate spring, the first direction being a long side direction or a short side direction;

wherein, the embedding both ends of the fiber section in the layer of fiber felt into the at least one layer of prepreg in an arch form through a barbed needle comprises:

moving the needle head along a second direction perpendicular to the first direction, and repeatedly inserting the needle head into the at least one layer of prepreg through the layer of fiber mat in the moving process until the needle head is located at the edge position of the at least one layer of prepreg; wherein the needle inserts both ends of the fiber segment into the at least one layer of prepreg in an arch form through the barb in the process of repeatedly inserting the at least one layer of prepreg.

6. The method of claim 5, wherein said repeatedly inserting said needle through said layer of fiber mat into said at least one layer of prepreg during said moving comprises:

and controlling the actual density of the needle inserted into the at least one layer of prepreg by controlling the moving speed of the needle.

7. The method of claim 5, wherein the density of the needles inserted into the at least one layer of prepreg is in the range of 2 to 200 needles per square centimeter.

8. The method according to claim 1, wherein the prepreg comprises a first sheet-like prepreg that is a sheet-like prepreg obtained by impregnating fiber yarns in a matrix material, and a second sheet-like prepreg that is a sheet-like prepreg obtained by impregnating fiber cloth in a matrix material;

wherein, lay the prepreg the same with combined material leaf spring body shape in the die cavity of mould to obtain preforming leaf spring, include:

and alternately laying the first sheet-shaped prepreg and the second sheet-shaped prepreg in the die cavity to obtain the preformed plate spring.

9. The method of claim 8, wherein a first and a last layer of sheet prepreg in the pre-formed leaf spring proximate the mold cavity are both the second sheet prepreg.

10. The method according to claim 1, wherein the at least one layer of prepreg has a number of layers in the range of 1 to 10 and the length of the fiber section is in the range of 20 to 100 mm.

11. A composite leaf spring body, comprising:

a composite leaf spring body made according to the method of any one of claims 1 to 10.

12. A leaf spring assembly, comprising:

the composite plate spring body prepared according to the method of any one of claims 1 to 10, wherein metal lugs are fixedly arranged at two ends of the composite plate spring body and fixedly connected with a vehicle frame, and the middle part of the composite plate spring body is fixed on a vehicle axle through a U-shaped bolt.

Technical Field

The present invention relates to a suspension for an automobile, and more particularly, to a method of manufacturing a prepreg-based composite leaf spring body for an automobile.

Background

With the increasing consumption of global fossil energy and the increasing emphasis on environmental issues, the speed of innovation of new materials and technology in the automobile industry is increasing. The lightweight car not only can greatly reduce the consumption of people to fossil energy, but also can improve the cargo capacity of the car and increase the service efficiency of the car. The composite material has the characteristics of light weight and high strength, and also has better shock absorption and fatigue life, so the composite material is widely applied to the field of automobiles.

The composite material is widely researched by a plurality of automobile manufacturers in recent years as a plate spring material for automobiles, and is also commercially applied to a part of automobile models.

In the related art, the forming process of the composite plate spring is generally divided into a continuous Filament Winding (fiber Winding) process and a compression Molding (Compressing Molding) process.

Most of manufacturers research and develop composite material plate springs by adopting a die pressing process, the precision of the composite material plate springs is high relative to a fiber winding process, and the surfaces of the composite material plate springs are smooth after products are formed without secondary processing. Resin Transfer Molding (RTM) is a typical Molding process, and specifically, a preformed fiber reinforcement material is placed in a mold cavity that requires peripheral sealing and fastening and ensures that the Resin flows smoothly inside; after the mould is closed, a certain amount of resin is injected, and after the resin is solidified, the desired product can be obtained by demoulding.

However, in the case of the press molding process, since the preformed reinforcing fiber material needs to be impregnated by the injected resin flowing in the sealed mold after the mold is sealed, if the resin does not flow smoothly, the performance of the plate spring is affected. Different structures which are beneficial to resin flowing are designed according to components with different shapes under normal conditions, and meanwhile, enough time is consumed for fiber infiltration, so that the requirements of resin flowing, mold filling and fiber infiltration can be met; but also results in excessive equipment development costs and time costs for the mold. Therefore, how to produce the plate spring meeting the performance requirement on the basis of the development cost and the time cost of the control equipment is a technical problem which needs to be solved urgently in the field.

Disclosure of Invention

The application provides a preparation method of a composite plate spring body based on prepreg molding, which can be used for producing a plate spring meeting performance requirements on the basis of controlling equipment research and development cost and time cost.

In a first aspect, the present application provides a method for preparing a composite leaf spring body based on prepreg molding, including:

laying a prepreg with the same shape as the composite plate spring body in a die cavity of a die to obtain a preformed plate spring; in the laying process, when at least one layer of prepreg is laid, a layer of fiber felt is laid on the surface of the at least one layer of prepreg, and two ends of a fiber segment in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a barbed needle head;

closing the mold and injecting a resin material;

the preformed leaf spring is cured by means of pressure and heat to obtain a composite leaf spring body.

In the embodiment, a layer of fiber felt is laid on the surface of at least one layer of prepreg, and two ends of a fiber section in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a needle head with a barb, so that when the prepreg is composed of fiber yarns, the fiber yarn direction of a unidirectional fiber yarn in the curing process can be prevented from being disordered, the fiber yarns in the vertical direction can be enriched, the interlaminar strength, the interlaminar fracture toughness and the fatigue life can be further improved, and the composite plate spring body can meet the performance requirements; in addition, in the process of embedding the two ends of the fiber section in the layer of fiber felt into the at least one layer of prepreg in an arch form through the barbed needle, a space with the size of the needle is formed in the at least one layer of prepreg through the needle, and the space can meet the requirements of resin flowing mold filling and fiber infiltration; specifically, on one hand, the space can be used for flowing of resin, a structure which is beneficial to flowing of the resin is avoided being specially designed, and the research and development cost of equipment is reduced; on the other hand, the space can also increase the contact area of the resin and the prepreg, and further can reduce the time requirement of the fiber infiltration process, namely reduce the time cost.

In short, by laying a layer of fiber felt on the surface of the at least one layer of prepreg and embedding the two ends of the fiber segments in the layer of fiber felt into the at least one layer of prepreg in an arch form through a barbed needle, the leaf spring meeting the performance requirements can be produced on the basis of development cost and time cost of control equipment.

In some possible implementations, the length of the fiber section is determined according to the thickness of the at least one layer of prepreg for each layer of fiber mat in the preformed leaf spring.

In some possible implementations, the at least one layer of prepreg has a thickness N; wherein the length of the fiber segment is greater than or equal to 2N + L + P, wherein L is proportional to the size of the barb, P is the offset, and N, L, P are all values greater than 0.

In this embodiment, the length of this fiber section is designed to be more than or equal to 2 × N + L + P, can guarantee that the degree of depth that the fiber section was embedded is more than or equal to the thickness of this at least one layer of preimpregnation material, be equivalent to, through the syringe needle that has the barb, imbed the both ends of the fiber section in this one deck fibrofelt in this at least one layer of preimpregnation material and the fibrofelt of this at least one layer of preimpregnation material below with the form of arch, can guarantee to have the intersection between the fiber section in two-layer fibrofelt promptly, and then, can further promote the intensity of composite leaf spring body.

In some possible implementations, the length of the fiber section is proportional to the total thickness of the prepreg that has been laid in the mold for each layer of fiber mat in the preformed leaf spring.

In this embodiment, the length of the fiber segment is designed to be in direct proportion to the total thickness of the prepreg laid in the mold, and it can be ensured that the depth of embedding of the fiber segment is greater than or equal to the thickness of the at least one layer of prepreg, that is, the two ends of the fiber segment in the layer of fiber mat are embedded into the at least one layer of prepreg and the fiber mat below the at least one layer of prepreg in an arched manner through the needle head with the barb, that is, it can be ensured that an intersection exists between the fiber segments in the two layers of fiber mats, and further, the strength of the composite plate spring body can be further improved.

In some possible implementations, at least one row of the needles having the same size as the mold cavity is disposed along a first direction of the preformed plate spring, the first direction being a long side direction or a short side direction;

wherein, should pass through the syringe needle that has the barb, imbed the both ends of the fibrous section in this one deck fibre felt in this at least one deck preimpregnation material in the form of arch, include:

moving the needle head along a second direction perpendicular to the first direction, and repeatedly inserting the needle head into the at least one layer of prepreg through the layer of fiber mat in the moving process until the needle head is positioned at the edge of the at least one layer of prepreg; wherein the needle inserts both ends of the fiber segment into the at least one layer of prepreg in an arch form through the barb during repeated insertion of the at least one layer of prepreg.

In the embodiment of the application, at least one row of the needles with the same size as the die cavity is arranged along the first direction of the preformed plate spring, and in the moving process of the needles, the needles are designed to pass through the layer of the fiber mat and are repeatedly inserted into the at least one layer of the prepreg until the needles are positioned at the edge of the at least one layer of the prepreg, so that the prepreg and the fiber mat which are paved can be subjected to needling operation, the process complexity of the needling operation is further reduced, and the flowing operation and the batch production are facilitated.

In some possible implementations, the repeatedly inserting the needle through the layer of fiber mat into the at least one layer of prepreg during the moving includes:

and controlling the actual density of the needle inserted into the at least one layer of prepreg by controlling the moving speed of the needle.

In this embodiment, through the mode of the moving speed of this syringe needle of control, the actual density of this syringe needle insertion this at least one deck preimpregnation material can reduce the performance requirement to the syringe needle, avoids involving special syringe needle, can reduce research and development cost and equipment cost, and then, can the effective control combined material leaf spring body's manufacturing cost.

In some possible implementations, the density of the needles inserted into the at least one layer of prepreg ranges from 2 to 200 needles per square centimeter.

In some possible implementations, the prepreg includes a first sheet-shaped prepreg that is made by impregnating fiber filaments in a matrix material, and a second sheet-shaped prepreg that is made by impregnating fiber cloth in a matrix material;

wherein, should lay the prepreg the same with combined material leaf spring body shape in the die cavity of mould to obtain preforming leaf spring, include:

and alternately laying the first sheet-shaped prepreg and the second sheet-shaped prepreg in the mold cavity to obtain the preformed plate spring.

In this embodiment, through the mode of laying this first slice preimpregnation material and this second slice preimpregnation material in turn, form this preforming leaf spring, be equivalent to, combined material leaf spring body is under the condition of atress, and this fibre cloth can alleviate the interlaminar shear that the cellosilk bore, is favorable to avoiding taking place the dislocation between the cellosilk in the first slice preimpregnation material, and then, can guarantee the performance of combined material leaf spring body. Optionally, the fiber cloth in the second sheet-shaped prepreg includes two fiber yarns in the vertical direction, and the two fiber yarns in the vertical direction and the fiber yarn in the first sheet-shaped prepreg both form an included angle of 45 degrees. The 45-degree included angle can be used for improving the stress performance of the fiber cloth.

In some possible implementations, the first and last layers of sheet prepreg in the pre-formed leaf spring proximate to the mold cavity are both the second sheet prepreg.

In some possible implementations, the number of layers of the at least one layer of prepreg is in a range of 1 to 10, and the length of the fiber section is in a range of 20 to 100 mm.

In a second aspect, there is provided a composite leaf spring body comprising:

a composite leaf spring body made according to the first aspect or the method described in any one of the possible implementations of the first aspect.

In a third aspect, a leaf spring assembly is provided, comprising:

the composite plate spring body is prepared according to the first aspect or any one of the possible implementation manners of the first aspect, the two ends of the composite plate spring body are fixedly provided with metal lugs, the metal lugs are fixedly connected with a vehicle frame, and the middle part of the composite plate spring body is fixed on an axle through a U-shaped bolt.

Drawings

Fig. 1 is a schematic view of the installation of the leaf spring assembly provided in the present application.

Fig. 2 is a schematic view of a composite leaf spring assembly provided in an embodiment of the present application.

Fig. 3 is a schematic flow chart of a method for manufacturing a composite leaf spring body based on prepreg molding provided in an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

The leaf spring can be placed in the longitudinal direction or in the transverse direction on the motor vehicle. The latter has to be provided with additional guiding force-transmitting devices for transmitting longitudinal force, which makes the structure complicated and the mass enlarged, so the latter is only applied to a few light and miniature vehicles. The longitudinal leaf spring can transmit various forces and moments, has a guiding function, and is simple in structure, so that the longitudinal leaf spring is widely applied to automobiles.

Fig. 1 is a schematic view of the installation of the leaf spring assembly provided in the present application.

As shown in fig. 1, the leaf spring assembly includes a leaf spring body 13, two U-bolts 14 are provided in the middle of the leaf spring body 13 for fixing the leaf spring body 13 to the axle 15, and the front end of the leaf spring body 13 is fixed to the vehicle body 11 (frame) through the front rolling lug 131 of the leaf spring body 13 and the front bracket 12; the rear end of the steel plate leaf spring body 13 is fixed to the vehicle body 11 (vehicle frame) via the rear lug 132 of the steel plate leaf spring body 13, the lug 16, and the rear bracket 17.

The steel plate leaf spring body 13 can be composed of a plurality of steel plates, the width of the single steel plate body is unchanged, the thickness of the single steel plate body is equal to the thickness of the single steel plate body, the single steel plate body has two types of sections, namely an equal section and a variable section, the variable section is also divided into a linear variable section and a parabolic variable section, and the parabolic variable section is mostly adopted for the variable section leaf spring because the stress of each part of the parabolic variable section is equal.

With technological development, composite materials are increasingly used for automotive suspension spring elements. The composite material has high specific strength modulus, and good fatigue resistance, damping performance and corrosion resistance, so that the composite material is used as an elastic element, the smoothness and comfort of a vehicle can be greatly improved, the mass is only about 1/4 of a steel plate spring, the fuel efficiency is effectively improved, the unsprung mass is reduced, the unsprung vibration is reduced, the service life is greatly prolonged, the elastic element does not need to be replaced within the service life range of the whole vehicle, and the use and maintenance cost of the whole vehicle is relatively low.

The concept of composite material means that one material can not meet the use requirement, and two or more materials are required to be compounded together to form another material which can meet the requirement of people, namely the composite material. As an example, a single glass fiber, although strong, is loose, can only withstand tensile forces, cannot withstand bending, shearing, and compressive stresses, and cannot be easily formed into a fixed geometric shape, which is a loose body. If they are bonded together with synthetic resin, they can be made into various rigid products with fixed shapes, which can bear not only tensile stress, but also bending, compression and shearing stress, and can be formed into glass fiber reinforced plastic matrix composite material. Because the strength of the glass fiber reinforced plastic is equivalent to that of steel, the glass fiber reinforced plastic also contains glass components and has the properties of color, shape, corrosion resistance, electric insulation, heat insulation and the like similar to glass, and the glass fiber reinforced plastic can be also called as glass fiber reinforced plastic.

Composite materials are of many types and generally consist of a reinforcement material and a matrix material, for example, reinforced concrete is also a composite material, concrete is a matrix, and reinforced steel is a reinforcement material.

The matrix material includes, but is not limited to, epoxy resin, polyester resin, thermoplastic resin, and the like. For example, the matrix material may be a resin matrix, i.e. a matrix of a resin-based composite material. The resin matrix refers to a glue solution system consisting of resin and a curing agent. As an example, the resin matrix may include a thermosetting resin and a thermoplastic resin. Thermosetting resins can be heated and molded only once and cured during processing to form infusible and insoluble network cross-linked high molecular compounds, and thus cannot be regenerated. The resin matrix of the composite material is mainly thermosetting resin. Thermosetting resins include, but are not limited to: phenolic resins, urea-formaldehyde resins, melamine-formaldehyde resins, epoxy resins, unsaturated resins, polyurethanes, polyimides, and the like. Reinforcing materials include, but are not limited to, carbon fibers, glass fibers, aramid fibers, and the like.

Reinforcing materials include, but are not limited to, carbon fibers, glass fibers, aramid fibers, and the like. The reinforcing material may be reinforcing fibres (Reinforced fibers), i.e. reinforcement of a resin-based composite material. By way of example, the reinforcing material includes, in terms of geometry, zero-dimensional particles, one-dimensional fibers, two-dimensional sheets (e.g., cloths or felts), and three-dimensional solid structures. Inorganic reinforcing materials and organic reinforcing materials, which may be synthetic or natural, are classified by their properties. The inorganic reinforcing material may be fibrous, such as inorganic glass fibers, carbon fibers, and a small amount of ceramic fibers such as silicon carbide, and the organic reinforcing material may include aramid fibers (aramid fibers) and the like.

As an example, the reinforcing material of the composite plate spring body according to the present application may be glass fiber, carbon fiber, or a fiber bundle composed of glass fiber and carbon fiber, and the matrix material thereof may be epoxy resin or the like, which may also be referred to as a fiber-Reinforced Plastic (FRP) plate spring body.

Compared with the traditional metal material, the characteristics of the composite plate spring are mainly characterized by high specific strength, high specific modulus, good temperature resistance, good impact resistance, strong designability, more than 70% weight reduction, safe fracture and the like. Many foreign countries have used composite leaf springs in mass production vehicles, and many automobile manufacturers both at home and abroad are developing composite leaf springs. The installation of a composite leaf spring is similar to the installation of a steel leaf spring, requiring the middle to be fixed to the axle like a steel leaf spring, with both ends connected to the body. However, since it is difficult to make the eye at both ends of the composite plate spring, it is necessary to make the member like the eye.

Fig. 2 is a schematic view of a composite leaf spring assembly provided in an embodiment of the present application.

As shown in fig. 2, the composite leaf spring assembly 20 may include a composite leaf spring body 23, both ends of the composite leaf spring body 23 being provided with a lug-like member 231 and 232, respectively, to connect both ends of the composite leaf spring body 23 to a vehicle body (frame); the middle part of the composite leaf spring body 23 is fixed to the axle by a U-bolt 24. As one example provided herein, the lug-like members 231 and 232 may be frame hinge barrels. Optionally, the ear-like members 231 and 232 may further include a plate spring clamping plate, and the frame hinge tube is fixedly connected to the plate spring clamping plate, for example, the plate spring clamping plate and the frame hinge tube may form a U-shaped structure; alternatively, the plate spring clamping plate may be disposed inside the composite plate spring body 23, or may be fixedly connected to the composite plate spring body 23 through a fastening bolt.

The forming process of the composite plate spring is generally classified into a continuous Filament Winding (Filament Winding) process and a compression Molding (compression Molding) process.

Most of manufacturers research and develop composite material plate springs by adopting a die pressing process, the precision of the composite material plate springs is high relative to a fiber winding process, and the surfaces of the composite material plate springs are smooth after products are formed without secondary processing. Resin Transfer Molding (RTM) is a typical Molding process, and specifically, a preformed fiber reinforcement material is placed in a mold cavity that requires peripheral sealing and fastening and ensures that the Resin flows smoothly inside; after the mould is closed, a certain amount of resin is injected, and after the resin is solidified, the desired product can be obtained by demoulding.

However, in the case of the press molding process, since the preformed reinforcing fiber material needs to be impregnated by the injected resin flowing in the sealed mold after the mold is sealed, if the resin does not flow smoothly, the performance of the plate spring is affected. Different structures which are beneficial to resin flowing are designed according to components with different shapes under normal conditions, and meanwhile, enough time is consumed for fiber infiltration, so that the requirements of resin flowing, mold filling and fiber infiltration can be met; but also results in excessive equipment development costs and time costs for the mold.

Based on the method, the composite material plate spring body is formed on the basis of the prepreg, and the plate spring meeting performance requirements can be produced on the basis of controlling equipment research and development cost and time cost. For example, on the basis of controlling the development cost and the time cost of equipment, the plate spring body can meet the requirements of the composite plate spring body on the retention rates of bending strength, interlaminar shear strength and the like, particularly the requirement on the retention rate of mechanical properties in a high-temperature scene. Wherein the interlaminar shear strength is used to evaluate interlaminar performance.

Fig. 3 is a schematic flow chart of a method 30 for manufacturing a composite leaf spring body based on prepreg molding according to an embodiment of the present application.

As shown in fig. 3, the preparation method 30 may include:

s31, laying a prepreg which is the same as the composite leaf spring in shape in a die cavity of a die to obtain a preformed leaf spring; in the laying process, when at least one layer of prepreg is laid, a layer of fiber felt is laid on the surface of the at least one layer of prepreg, and two ends of a fiber segment in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a barbed needle head;

s32, closing the mold and injecting a resin material;

and S33, curing the preformed plate spring by pressurizing and heating to obtain the composite plate spring body.

In the embodiment, a layer of fiber felt is laid on the surface of at least one layer of prepreg, and two ends of a fiber section in the layer of fiber felt are embedded into the at least one layer of prepreg in an arch form through a needle head with a barb, so that when the prepreg is composed of fiber yarns, the fiber yarn direction of a unidirectional fiber yarn in the curing process can be prevented from being disordered, the fiber yarns in the vertical direction can be enriched, the interlaminar strength, the interlaminar fracture toughness and the fatigue life can be further improved, and the composite plate spring body can meet the performance requirements; in addition, in the process of embedding the two ends of the fiber section in the layer of fiber felt into the at least one layer of prepreg in an arch form through the barbed needle, a space with the size of the needle is formed in the at least one layer of prepreg through the needle, and the space can meet the requirements of resin flowing mold filling and fiber infiltration; specifically, on one hand, the space can be used for flowing of resin, a structure which is beneficial to flowing of the resin is avoided being specially designed, and the research and development cost of equipment is reduced; on the other hand, the space can also increase the contact area of the resin and the prepreg, and further can reduce the time requirement of the fiber infiltration process, namely reduce the time cost.

In short, by laying a layer of fiber felt on the surface of the at least one layer of prepreg and embedding the two ends of the fiber segments in the layer of fiber felt into the at least one layer of prepreg in an arch form through a barbed needle, the leaf spring meeting the performance requirements can be produced on the basis of development cost and time cost of control equipment.

In the field of manufacturing process, the process parameters such as the matrix material, the reinforcing material, the molding method and the like must be matched with each other, otherwise, the reinforcing effect of the fiber cannot be fully exerted, and further, the strength is greatly influenced. In general, for different products (for example, composite materials formed by different matrix materials and reinforcing materials), a set of preparation processes specially designed for the products are required to achieve the expected effect. The scheme provided by the application is that aiming at the mould pressing technology, in the operation process of laying the prepreg, a 'needling' operation flow is specially designed so as to improve the retention rates of bending strength, interlaminar shear strength and the like.

In addition, the specific type of the prepreg is not limited in the embodiments of the present application.

Prepreg refers to a prepreg sheet product made by impregnating a reinforcing material in a Matrix (Matrix) material, and is an intermediate material of a composite material.

By way of example, prepregs include, but are not limited to: unidirectional prepreg, unidirectional fabric prepreg, fabric prepreg. The prepreg is divided into thermosetting resin prepreg and thermoplastic resin prepreg according to different resin matrixes; according to different reinforcing materials, the prepreg is divided into carbon fiber (fabric) prepreg, glass fiber (fabric) prepreg and aramid fiber (fabric) prepreg; according to the difference of the fiber length, the prepreg is divided into short fiber (4176mm or less) prepreg, long fiber (1217mm) prepreg and continuous fiber prepreg; according to different curing temperatures, the prepreg can be divided into a medium-temperature curing (120 ℃) prepreg, a high-temperature curing (180 ℃) prepreg, a prepreg with the curing temperature exceeding 200 ℃ and the like. For example, in the case of a carbon fiber prepreg, the carbon fiber prepreg is a prepreg in which the surface of carbon fibers is impregnated with a resin but is not cured by heating, and is used as a spare material for subsequent molding and curing. The preparation method of the prepreg comprises a dry method and a wet method. In the dry process, resin powder is attached to the fibers and partially melted to form a composite in which the resin is discontinuous and the fibers are not fully saturated with resin. In the wet process, the fibers are impregnated with a resin solution, dried and cured to form a composite in which the resin is substantially continuous and the fibers are substantially saturated with resin.

The specific types of the matrix material and the reinforcing material may be as described above, and are not described herein again to avoid repetition.

In some embodiments, the length of the fiber section is determined according to the thickness of the at least one layer of prepreg for each layer of fiber mat in the preformed leaf spring. As an example, the at least one layer of prepreg has a thickness of N; wherein the length of the fiber segment is greater than or equal to 2N + L + P, wherein L is proportional to the size of the barb, P is the offset, and N, L, P are all values greater than 0.

In this embodiment, the length of this fiber section is designed to be more than or equal to 2 × N + L + P, can guarantee that the degree of depth that the fiber section was embedded is more than or equal to the thickness of this at least one layer of preimpregnation material, be equivalent to, through the syringe needle that has the barb, imbed the both ends of the fiber section in this one deck fibrofelt in this at least one layer of preimpregnation material and the fibrofelt of this at least one layer of preimpregnation material below with the form of arch, can guarantee to have the intersection between the fiber section in two-layer fibrofelt promptly, and then, can further promote the intensity of composite leaf spring body.

In some embodiments, the length of the fiber section is proportional to the total thickness of prepreg that has been laid in the mould for each layer of fiber mat in the pre-formed leaf spring.

In this embodiment, the length of the fiber segment is designed to be in direct proportion to the total thickness of the prepreg laid in the mold, and it can be ensured that the depth of embedding of the fiber segment is greater than or equal to the thickness of the at least one layer of prepreg, that is, the two ends of the fiber segment in the layer of fiber mat are embedded into the at least one layer of prepreg and the fiber mat below the at least one layer of prepreg in an arched manner through the needle head with the barb, that is, it can be ensured that an intersection exists between the fiber segments in the two layers of fiber mats, and further, the strength of the composite plate spring body can be further improved.

In some embodiments, at least one row of the needles having the same size as the mold cavity is arranged along a first direction of the preformed plate spring, the first direction being a long side direction or a short side direction; wherein, the S31 may include:

moving the needle head along a second direction perpendicular to the first direction, and repeatedly inserting the needle head into the at least one layer of prepreg through the layer of fiber mat in the moving process until the needle head is positioned at the edge of the at least one layer of prepreg; wherein the needle inserts both ends of the fiber segment into the at least one layer of prepreg in an arch form through the barb during repeated insertion of the at least one layer of prepreg.

In the embodiment of the application, at least one row of the needles with the same size as the die cavity is arranged along the first direction of the preformed plate spring, and in the moving process of the needles, the needles are designed to pass through the layer of the fiber mat and are repeatedly inserted into the at least one layer of the prepreg until the needles are positioned at the edge of the at least one layer of the prepreg, so that the prepreg and the fiber mat which are paved can be subjected to needling operation, the process complexity of the needling operation is further reduced, and the flowing operation and the batch production are facilitated.

In one implementation, the actual density of the needles inserted into the at least one layer of prepreg is controlled by controlling the speed of movement of the needles.

In this embodiment, through the mode of the moving speed of this syringe needle of control, the actual density of this syringe needle insertion this at least one deck preimpregnation material can reduce the performance requirement to the syringe needle, avoids involving special syringe needle, can reduce research and development cost and equipment cost, and then, can the effective control combined material leaf spring body's manufacturing cost.

In one implementation, the density of the needles inserted into the at least one layer of prepreg is in the range of 2 to 200 needles per square centimeter.

Of course, the above numerical values are merely examples of the present application and should not be construed as limiting the present application. For example, in other alternative embodiments, the density of the needles inserted into the at least one layer of prepreg ranges from 50 to 100 needles per square centimeter. For another example, the density range of the needle inserted into the edge region of the at least one layer of prepreg is larger than the density range of the needle inserted into the central region of the at least one layer of prepreg; in one implementation, the density of the needles in at least one row in the edge region of the at least one layer of prepreg is greater than the density of the needles in the central region of the at least one layer of prepreg.

In some embodiments, the prepreg includes a first sheet-like prepreg that is made by impregnating fiber filaments in a matrix material, and a second sheet-like prepreg that is made by impregnating fiber cloth in a matrix material; wherein, the S31 may include:

and alternately laying the first sheet-shaped prepreg and the second sheet-shaped prepreg in the mold cavity to obtain the preformed plate spring.

In this embodiment, through the mode of laying this first slice preimpregnation material and this second slice preimpregnation material in turn, form this preforming leaf spring, be equivalent to, combined material leaf spring body is under the condition of atress, and this fibre cloth can alleviate the interlaminar shear that the cellosilk bore, is favorable to avoiding taking place the dislocation between the cellosilk in the first slice preimpregnation material, and then, can guarantee the performance of combined material leaf spring body. Optionally, the fiber cloth in the second sheet-shaped prepreg includes two fiber yarns in the vertical direction, and the two fiber yarns in the vertical direction and the fiber yarn in the first sheet-shaped prepreg both form an included angle of 45 degrees. The 45-degree included angle can be used for improving the stress performance of the fiber cloth.

It should be noted that the specific type of the fiber cloth is not limited in the examples of the present application. For example, the fiber cloth according to the embodiment of the present application may be a carbon fiber cloth, a carbon fiber fabric, a carbon fiber tape, a carbon fiber sheet, a prepreg, or the like. The composite material made of the carbon fiber has the characteristics of extremely high strength, ultralight weight, high temperature and high pressure resistance and the like.

In some embodiments, the first and last layers of sheet prepreg material in the pre-formed leaf spring adjacent the mould cavity are both the second sheet prepreg material.

In other words, the upper side and the lower side of the molded leaf spring body can be coated with a layer of fiber cloth.

In some embodiments, the at least one layer of prepreg has a number of layers in the range of 1 to 10 and the length of the fiber segment is in the range of 20 to 100 mm.

Of course, in other alternative embodiments, the range of the number of layers of the at least one layer of prepreg and/or the range of the length of the fiber segment may be other values, which is not specifically limited in the embodiments of the present application. For example, the number of layers of the at least one layer of prepreg is 20.

The application also provides the composite plate spring body prepared by the preparation method of the composite plate spring body based on prepreg molding. It is to be understood that the composite leaf spring body embodiments and the method embodiments of making the composite leaf spring body can correspond to each other and similar descriptions can be made with reference to specific embodiments of the composite material. For brevity, no further description is provided herein.

It should be understood that the leaf spring body, the composite leaf spring, and the composite leaf spring body described in this specification can all be resin-based fiber composite leaf spring bodies.

It will also be appreciated that the embodiments of the method of making a composite leaf spring body enumerated above may be performed by robotic or numerically controlled machining, and that the apparatus software or process for performing the method may perform the method by executing computer program code stored in memory. It should be noted that, without conflict, the embodiments and/or technical features in the embodiments described in the present application may be arbitrarily combined with each other, and the technical solutions obtained after the combination also fall within the protection scope of the present application. It should be understood that, in the various embodiments of the present application, the sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

Those of ordinary skill in the art will appreciate that the various illustrative methods of making described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.