Composite material interlayer air cylinder and manufacturing method

Abstract

The invention relates to a composite interlayer air cylinder and a manufacturing method, and belongs to the technical field of vehicle engineering. The air cylinder comprises an inner container, a fiber composite material inner layer, a light foam layer and a fiber composite material outer layer from inside to outside. The inner container is made of thermoplastic resin materials, a base body of the fiber composite material inner layer is thermosetting resin, the light foam layer is made of foaming resin materials, and the fiber composite material outer layer is made of thermosetting composite fiber resin prepreg or thermoplastic composite fiber resin prepreg. The inner container is used for sealing, the fiber composite material inner layer is used for bearing air pressure in the air cylinder, the fiber composite material outer layer is used for resisting external impact, the light foam layer is used for buffering, under the scenes of gravel impact and the like, external impact energy cannot extend to the internal fiber composite material inner layer, and therefore overall impact resistance is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle engineering, and in particular relates to a composite material sandwich air cylinder and a manufacturing method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] In rail vehicles, air cylinders are used to store dry, clean compressed air. In order to meet the demand for lightweight rail transit equipment, air cylinders are gradually developed into carbon fiber reinforced composite materials in addition to metal. The installation locations of air cylinders include the bottom and inside of the locomotive. When it is installed at the bottom of the locomotive with the help of a bracket, it will be exposed under the vehicle, so it will be impacted by more gravel or other objects during the high-speed movement of the vehicle. Due to the high relative speed, the impact of gravel will destroy the integrity of the carbon fiber reinforced material air cylinder, especially causing cracks, delamination and other defects in the composite material layer, affecting the service life of the air cylinder; it may even penetrate the side wall of the composite material, posing a major hidden danger to driving safety.

[0004] Therefore, it is necessary to improve the existing composite material air cylinder to enhance its overall impact resistance. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a composite sandwich air cylinder and a manufacturing method thereof, which adopts a sandwich structure, wherein the inner layer is a thermoplastic liner, the middle layer is a lightweight foam, and the outer layer is an impact-resistant material, so as to enhance the impact resistance of the air cylinder.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, a composite sandwich air cylinder comprises, from inside to outside: an inner liner, a fiber composite inner layer, a lightweight foam layer and a fiber composite outer layer;

[0008] The inner liner is made of thermoplastic resin, the matrix of the inner layer of the fiber composite material is thermosetting resin, the lightweight foam layer is made of foaming resin, and the raw material for preparing the outer layer of the fiber composite material is thermosetting composite fiber resin prepreg or thermoplastic composite fiber resin prepreg.

[0009] Optionally, the inner liner is made of one of PA, HDPE and XLPE.

[0010] Optionally, the thermosetting resin is one of epoxy resin, PF and SI.

[0011] Optionally, the lightweight foam layer is made of one of PET and PMI.

[0012] Optionally, the fibers in the inner layer of the fiber composite material are carbon fibers.

[0013] Optionally, the fiber material of the outer layer of the fiber composite material includes one or more of glass fiber and carbon fiber.

[0014] Optionally, the matrix of the fiber composite material inner layer and the fiber composite material outer layer is a thermosetting resin of the same grade.

[0015] Optionally, the radius of curvature of the outer layer of the fiber composite material at the shoulder position of the air cylinder is greater than the radius of curvature of the inner layer of the fiber composite material.

[0016] In a second aspect, a method for preparing the composite sandwich air cylinder comprises:

[0017] S1, preparing an inner liner, winding carbon fiber on the surface of the inner liner, and performing resin scraping during the winding process to obtain a fiber layer;

[0018] S2, wrapping the surface of the fiber layer in S1 with a heat shrink tape, and then performing rotational curing under a set winding tension, and removing the heat shrink tape after the resin of the fiber layer shows viscosity;

[0019] S3, laminating the lightweight foam cut into a set shape onto the surface of the fiber layer to obtain a lightweight foam layer;

[0020] S4. Winding a fiber material prepreg tape on the outside of the lightweight foam layer in a set manner, and obtaining an outer layer of the fiber composite material after curing.

[0021] Optionally, in S1, the inner liner is prepared by blow molding or rotational molding.

[0022] Optionally, in S1, the resin scraping method is to use a scraper to scrape off excess resin so that the fiber volume content of the fiber layer is more than 60%.

[0023] Optionally, in S2, the heat shrink tape is a BOPP heat shrink tape.

[0024] Optionally, in S2, a pressurized material is wrapped around the outside of the heat shrinkable tape with a tension of 50 to 70 N, and the rotational curing method is to heat and cure while rotating the workpiece.

[0025] Optionally, in S4, when the raw material for preparing the outer layer of the fiber composite material is a thermosetting composite fiber resin prepreg, the curing method is to heat and cure the entire workpiece after winding is completed; when the raw material for preparing the outer layer of the fiber composite material is a thermoplastic composite fiber resin prepreg, heating and curing are performed by winding and heating at the same time.

[0026] The beneficial effects of the present invention are:

[0027] 1. The composite sandwich air cylinder structure provided by the present invention comprises an inner liner, an inner layer of fiber composite material, a lightweight foam layer and an outer layer of fiber composite material. Among them, the inner liner is used for sealing, the inner layer of fiber composite material is used to withstand the air pressure inside the air cylinder, the outer layer of fiber composite material is used to resist external impact, and the lightweight foam layer is used for buffering. In scenarios such as gravel impact, the external impact energy cannot extend to the inner layer of fiber composite material inside, thereby achieving overall impact resistance. At the same time, the lightweight foam can make the shapes of the outer layer of fiber composite material and the inner layer of fiber composite material not completely consistent, so that the shape structures of the inner layer of fiber composite material used to withstand internal pressure and the outer layer of fiber composite material used to withstand external impact are more reasonable, thereby achieving a smooth transition of the shoulder.

[0028] 2. The use of heat shrink tape in the preparation method of the present invention can achieve a smooth surface effect, avoid surface defects such as wrinkles, and lay a good foundation for the subsequent bonding of the lightweight foam layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, 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.

[0030] Figure 1 This is a schematic diagram of the cross-sectional structure of the cylinder wall of the composite sandwich air cylinder in Example 1.

[0031] Figure 2 This is a schematic diagram of the cross-sectional structure of the shoulder in Example 1.

[0032] Among them, 1. liner, 2. fiber composite material inner layer; 3. lightweight foam layer; 4. fiber composite material outer layer; 5. shoulder after shape correction; 6. shoulder before shape correction. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0035] A composite sandwich air cylinder, comprising, from inside to outside: an inner liner, an inner layer of fiber composite material arranged outside the inner liner, a light foam layer and an outer layer of fiber composite material;

[0036] The inner liner is made of thermoplastic resin, the matrix of the inner layer of the fiber composite material is thermosetting resin, the lightweight foam layer is made of foaming resin, and the raw material for preparing the outer layer of the fiber composite material is thermosetting composite fiber resin prepreg or thermoplastic composite fiber resin prepreg.

[0037] Through the above arrangement, the inner liner is used for sealing, the inner layer of the fiber composite material is used to withstand the air pressure inside the air cylinder, the outer layer of the fiber composite material is used to resist external impact, and the lightweight foam layer is used for buffering, so as to obtain an internal pressure-bearing container that is resistant to external impact as a whole; the lightweight foam can make the shapes of the outer layer and the inner layer of the fiber composite material not completely consistent by changing the local thickness, thereby making the shape structure of the inner liner and the outer contour of the air cylinder more reasonable, achieving a smooth transition of the shoulder, and further improving the impact resistance.

[0038] Optionally, the inner liner is made of one of materials such as PA (polyamide), HDPE (high-density polyethylene) and XLPE (cross-linked polyethylene), which is used to achieve the sealing performance of the air cylinder.

[0039] Optionally, the thermosetting resin is one of epoxy resin, PF (phenolic resin) and SI (silicone resin), which can obtain an inner layer of a fiber composite material after curing and forming, thereby preventing the inner layer material from deforming during subsequent heating.

[0040] Optionally, the lightweight foam layer material includes one or more materials such as PET (polyethylene terephthalate) and PMI (polymethacrylimide), which is used to provide cushioning when the air cylinder is subjected to external impact. The material of the lightweight foam layer in this application has a certain rigidity and can be cut into a set shape to adjust the wall thickness at different positions. It can be thickened at the shoulder of the air cylinder, so that the shape of the outer layer of the fiber composite material is more suitable for withstanding external impact.

[0041] Optionally, the fibers of the inner layer of the fiber composite material are carbon fibers, which are used to improve the pressure-bearing capacity of the inner liner.

[0042] Optionally, the fiber material of the outer layer of the fiber composite material includes one or more of glass fiber and carbon fiber, so as to improve the ability to resist the impact of external objects such as gravel.

[0043] Optionally, the matrix of the inner layer of the fiber composite material and the outer layer of the fiber composite material is a thermosetting resin of the same resin grade to simplify material preparation in the production process; or, since the impact resistance of thermoplastic resin is higher than that of thermosetting resin, in order to further improve the impact resistance of the air cylinder, the matrix of the outer layer of the fiber composite material is a thermoplastic resin.

[0044] Optionally, the radius of curvature of the outer layer of the fiber composite material at the shoulder position of the air cylinder is greater than the radius of curvature of the inner layer of the fiber composite material, and the thickness of the lightweight foam layer at the shoulder position is greater to enhance the ability of the shoulder position to resist external impact.

[0045] In a second aspect, a method for preparing the composite sandwich air cylinder comprises:

[0046] S1, preparing an inner liner, winding carbon fiber on the surface of the inner liner, and performing resin scraping during the winding process to obtain a fiber layer;

[0047] S2, wrapping the surface of the fiber layer in S1 with a heat shrink tape, and then performing rotational curing under a set winding tension, and removing the heat shrink tape after the resin of the fiber layer shows viscosity;

[0048] S3, laminating the lightweight foam cut into a set shape onto the surface of the fiber layer to obtain a lightweight foam layer;

[0049] S4. Winding a fiber material prepreg tape on the outside of the lightweight foam layer in a set manner, and obtaining an outer layer of the fiber composite material after curing.

[0050] Optionally, in S1, the inner liner is prepared by blow molding or rotational molding to obtain an inner liner with good sealing properties.

[0051] Optionally, in S1, the resin scraping method is to use a scraper to scrape off excess resin so that the fiber volume content of the fiber layer is more than 60%, and the heating temperature is set according to the curing temperature of the thermosetting resin so that the inner layer inside the lightweight foam is fully heated; the inner layer of the fiber composite material is prepared by the scraping method using carbon fiber as raw material, which can reduce internal defects and improve the surface quality of the outer surface of the inner layer, thereby facilitating its close bonding with the outer lightweight foam.

[0052] Optionally, in S2, the heat shrink tape is a BOPP heat shrink tape, which is a common material in this field.

[0053] Optionally, in S2, a pressurizing material is wrapped around the outside of the heat shrinkable tape with a wrapping tension of 50 to 70 N to compact the heat shrinkable tape, and the rotational curing method is to heat and cure the workpiece while rotating it; the pressurizing material can be made of dry fibers (referring to carbon fibers or glass fiber bundles that are not soaked in resin for easy removal after curing) to make the fiber layer inside the heat shrinkable tape compact and obtain a smoother and flatter surface, and the heating and curing can be performed during the rotation process.

[0054] Optionally, in S2, the tube is heated and cured while rotating to allow the internal resin to flow to an appropriate degree, so that the resin is evenly distributed along the barrel, thereby promoting the formation of an inner layer of a fiber composite material with uniform thickness and performance.

[0055] Optionally, in S3, after the heat shrink tape is torn off, the lightweight foam is adhered to the outside of the fiber layer while the thermosetting resin of the fiber layer still remains sticky. During the process, the thermosetting resin is cooled and solidified, so that the fiber layer is transformed into an inner layer of the fiber composite material.

[0056] Optionally, in S4, when the raw material for preparing the outer layer of the fiber composite material is a thermosetting composite fiber resin prepreg, the curing method is to heat and cure the entire workpiece after the winding is completed; and a composite sandwich air cylinder is obtained.

[0057] Optionally, in S4, when the raw material for preparing the outer layer of the fiber composite material is a thermoplastic composite fiber resin prepreg, heating and curing are carried out by winding and heating at the same time, and the local heating position is located on the thermoplastic composite fiber resin prepreg; during the process, the prepreg in which the matrix resin reaches a molten state is wound layer by layer onto the outside of the lightweight foam layer in a set manner to obtain a composite sandwich air cylinder.

[0058] Example 1

[0059] A composite sandwich air cylinder, such as Figure 1 As shown, it comprises: an inner liner 1; a fiber composite material inner layer 2 and a fiber composite material outer layer 4 are arranged on the outer side of the inner liner 1, and a lightweight foam layer 3 is arranged between the fiber composite material inner layer 2 and the fiber composite material outer layer 4; the inner liner 1 is made of thermoplastic resin, the lightweight foam layer 3 is made of foamed resin, and the raw material for preparing the fiber composite material outer layer 4 (impact-resistant layer) is thermosetting resin prepreg of composite fiber;

[0060] like Figure 1 As shown, the resin materials of the fiber composite material inner layer 2 and the fiber composite material outer layer 4 are integrated at the air cylinder interface and wrap the lightweight foam layer 3.

[0061] The material of the inner tank 1 is HDPE, which is used to achieve the sealing performance of the air cylinder.

[0062] The lightweight foam layer 3 is made of PET and is used to provide cushioning when the air cylinder is subjected to external impact.

[0063] The fiber material of the fiber composite material inner layer 2 and the fiber composite material outer layer 4 is carbon fiber; the resin matrix of the fiber composite material inner layer 2 is epoxy resin, which has the same brand as the matrix resin of the fiber composite material outer layer 4 .

[0064] like Figure 2As shown, the curvature radius of the fiber composite outer layer 4 at the shoulder position of the air cylinder is greater than the curvature radius of the fiber composite inner layer 2, and the thickness of the lightweight foam layer 3 at the shoulder position is smaller to enhance the ability of the shoulder position to resist external impact. That is, before the shape correction, since the lightweight foam layer 3 is an equal thickness structure, the curvature radius of the shoulder 6 before the shape correction is smaller. After the shape correction, the thickness of the lightweight foam layer 3 is appropriately reduced at the shoulder position, so that the curvature radius of the shoulder 5 after the shape correction is larger, which is more conducive to resisting external impact than the shoulder 6 before the shape correction.

[0065] A method for preparing a composite sandwich air cylinder comprises:

[0066] S1, preparing an inner liner, winding a carbon fiber material on the surface of the inner liner, and performing resin scraping during the winding process to obtain a fiber layer;

[0067] S2, wrapping the surface of the fiber layer in S1 with a heat shrink tape, and then performing room temperature rotation pre-curing under a set winding tension, and removing the heat shrink tape after the resin of the fiber layer shows viscosity;

[0068] S3, laminating the lightweight foam cut into a set shape onto the surface of the fiber layer to obtain a lightweight foam layer;

[0069] S4. Winding a fiber material prepreg tape on the outside of the lightweight foam layer in a set manner, and obtaining an outer layer of the fiber composite material after curing.

[0070] In S1, the preparation method of the inner liner is blow molding, and the thickness of the inner liner is 4 mm.

[0071] In S1, the resin scraping method is to scrape off the resin with a scraper so that the fiber volume content of the fiber layer is 60%.

[0072] In S2, the heat shrinkable tape is a BOPP heat shrinkable tape; a carbon fiber bundle of dry fibers is wound around the outside of the heat shrinkable tape with a winding tension of 10N to compact the heat shrinkable tape, and the curing method is to rotate and cure on a rotating device to obtain an inner layer of the fiber composite material.

[0073] In S2, the heating parameters are set according to the DSC test analysis results, and the appropriate heating temperature and time are selected. The desired viscosity state is obtained after curing according to the curing operation time of the resin, and then the heat shrink tape is torn off, and then the lightweight foam is pasted to the outside of the sticky fiber layer.

[0074] In S4, the laying method of the fiber material prepreg tape is alternating spiral and hoop winding.

[0075] In S4, the curing method is rotary heating curing.

[0076] The air cylinder prepared in this embodiment includes, from the inside to the outside: an inner liner 1 of HDPE, an inner layer of a carbon fiber composite material of a resin matrix, a lightweight foam layer of PET and an outer layer of a glass fiber composite material of a resin matrix, which takes into account both the mechanical properties and processability of the material and has a high structural rigidity.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that the raw material for preparing the outer layer 4 (impact-resistant layer) of the fiber composite material is thermoplastic resin prepreg of composite fiber, and the resin matrix thereof is PA.

[0079] In the preparation method, S4 adopts the method of winding and heating and curing, and the local heating position is located on the thermoplastic composite fiber resin prepreg; during the process, the prepreg with the matrix resin in a molten state is wound layer by layer onto the outside of the lightweight foam layer in a set manner, so that it is gradually cooled and cured on the outside of the lightweight foam layer to improve production efficiency.

[0080] The air cylinder prepared in this embodiment includes, from the inside to the outside, an inner liner 1 of HDPE, an inner layer of carbon fiber composite material with epoxy resin matrix, a lightweight foam layer of PET and an outer layer of glass fiber composite material with HDPE matrix, thereby obtaining a composite sandwich air cylinder. The outer layer 4 of the fiber composite material adopts thermoplastic resin PA, which has stronger impact resistance.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite sandwich air cylinder, characterized in that: From inside to outside, it includes: liner, fiber composite inner layer, lightweight foam layer and fiber composite outer layer; The inner liner is made of thermoplastic resin, the matrix of the inner layer of the fiber composite material is thermosetting resin, the lightweight foam layer is made of foaming resin, and the raw material for preparing the outer layer of the fiber composite material is thermosetting composite fiber resin prepreg or thermoplastic composite fiber resin prepreg.

2. The composite sandwich air cylinder according to claim 1, characterized in that: The liner material is one of PA, HDPE and XLPE; Optionally, the thermosetting resin is one of epoxy resin, PF and SI; Optionally, the lightweight foam layer is made of one of PMI and PET; Optionally, the fibers in the inner layer of the fiber composite material are carbon fibers; Optionally, the fiber material of the outer layer of the fiber composite material includes one or more of glass fiber and carbon fiber.

3. The composite sandwich air cylinder according to claim 1, characterized in that: The matrix of the fiber composite material inner layer and the fiber composite material outer layer is thermosetting resin of the same grade.

4. A method for preparing a composite sandwich air cylinder as claimed in any one of claims 1 to 3, characterized in that: include: S1, preparing an inner liner, winding carbon fiber on the surface of the inner liner, and performing resin scraping during the winding process to obtain a fiber layer; S2, wrapping the surface of the fiber layer in S1 with a heat shrink tape, and then performing room temperature rotation pre-curing under a set winding tension, and removing the heat shrink tape after the resin of the fiber layer shows viscosity; S3, laminating the lightweight foam cut into a set shape onto the surface of the fiber layer to obtain a lightweight foam layer; S4. Winding a fiber material prepreg tape on the outside of the lightweight foam layer in a set manner, and obtaining an outer layer of the fiber composite material after curing.

5. The method for preparing the composite sandwich air cylinder according to claim 4, characterized in that: In S1, the inner liner is prepared by blow molding or rotational molding.

6. The method for preparing the composite sandwich air cylinder according to claim 4, characterized in that: In S1, the resin scraping method is to use a scraper to scrape off excess resin so that the fiber volume content of the fiber layer is more than 60%.

7. The method for preparing the composite sandwich air cylinder according to claim 4, characterized in that: In S2, the heat shrinkable tape is a BOPP heat shrinkable tape.

8. The method for preparing the composite sandwich air cylinder according to claim 7, characterized in that: In S2, a pressurizing material is wound around the outside of the heat shrinkable tape with a winding tension of 50 to 70 N, and the rotation curing method is to heat and cure the workpiece while rotating it.

9. The method for preparing the composite sandwich air cylinder according to claim 4, characterized in that: In S3, after the heat shrink tape is removed, the lightweight foam is adhered to the outside of the fiber layer while the inner resin is still sticky.

10. The method for preparing the composite sandwich air cylinder according to claim 4, characterized in that: In S4, when the raw material for preparing the outer layer of the fiber composite material is a thermosetting composite fiber resin prepreg, the curing method is to heat and cure the entire workpiece after winding is completed. When the raw material for preparing the outer layer of the fiber composite material is a thermoplastic composite fiber resin prepreg, heating and curing are performed by winding and heating at the same time.

Images