Fiber-reinforced air cylinder and manufacturing method

Abstract

The invention relates to a fiber reinforced air cylinder and a manufacturing method, and relates to the technical field of vehicle engineering. A fiber reinforced air cylinder comprises an inner container and a winding layer. The inner container is made of thermoplastic nylon materials, the winding layer is made of reinforced fiber prepreg tape, a base body of the reinforced fiber prepreg tape is made of thermoplastic nylon materials, and the thermoplastic nylon materials of the inner container and the winding layer are the same and are fused into a whole. The preparation method comprises the following steps: preparing the liner by using a rotational molding method; a reinforced fiber prepreg tape is wound on the outer side of the inner container according to the set winding direction, and the reinforced fiber prepreg tape wound on the air cylinder is heated to 250-300 DEG C through laser in the winding process. And the whole wound air cylinder is subjected to secondary curing, and the fiber-reinforced air cylinder product is obtained. The base bodies of the inner container and the winding layer of the air cylinder are made of the same thermoplastic material and can be fused into a whole in the preparation process, so that the layering problem does not exist, and the bonding strength of the inner container layer and the winding layer is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle engineering, and in particular relates to a fiber-reinforced 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 in brake components of rail transit subways, high-speed trains, heavy trucks, etc. In addition to bearing the internal air pressure (working pressure), they also need to withstand their own weight and high / low temperature effects. Traditional materials for air cylinders are mostly stainless steel or aluminum alloys, and their single weight is usually between 20 and 40 kilograms. In response to the demand for lightweight rail transit equipment, carbon fiber composite air cylinders have become an emerging development trend. The density of carbon fiber composite materials is only about 1.5g / cm 3 , with the characteristics of light weight, rust resistance, corrosion resistance, high and low temperature resistance and excellent fatigue resistance. Compared with traditional metal air cylinders, the air cylinder made of carbon fiber composite materials has achieved significant weight reduction, is easier to install, and has less vibration damage to the mounting bracket. In addition, its production process is short and efficient, and can meet the needs of locomotive use in various environments.

[0004] Air cylinders made of carbon fiber composite materials usually include two-layer structures, namely the air cylinder liner and the winding layer. Due to the limitations of materials and processing methods, the inner liner is mainly made of HDPE and nylon, and the winding layer is mainly made of thermosetting epoxy resin. The interface bonding between the two materials is poor. During the long-term operation of the air cylinder, due to the pressure difference generated by the flushing and exhausting gases and the influence of environmental aging due to large temperature differences, the air cylinder liner and the winding layer are easily separated, forming a gap, which affects the service life of the air cylinder. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a fiber reinforced air cylinder and a manufacturing method, wherein the air cylinder liner and the winding layer raw materials used are both thermoplastic materials, and during the preparation process the air cylinder liner and the winding layer are melted into one to eliminate the interface layer.

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

[0007] In a first aspect, a fiber-reinforced air cylinder includes an inner liner and a winding layer;

[0008] The raw material of the inner liner is thermoplastic nylon, the raw material of the winding layer is reinforcing fiber prepreg tape, the matrix of the reinforcing fiber prepreg tape is thermoplastic nylon, and the thermoplastic nylon material of the inner liner and the winding layer is the same and is melted into one.

[0009] Optionally, the thermoplastic nylon is PA6 or PA66, and the reinforcing fiber is carbon fiber and / or glass fiber.

[0010] Optionally, the reinforcing fibers in the winding layer are arranged according to a set winding direction.

[0011] In a second aspect, the method for preparing the above-mentioned fiber-reinforced air cylinder comprises the steps of:

[0012] S1, preparing the liner by rotational molding;

[0013] S2. Winding the reinforcing fiber prepreg tape on the outside of the inner tank according to the set winding direction. During the winding process, the reinforcing fiber prepreg tape wound on the air cylinder is heated by laser to 250-300° C.;

[0014] S3. The wound air cylinder is subjected to secondary curing at 70-90° C. to obtain a fiber-reinforced air cylinder product.

[0015] Optionally, in S1, the rotomoulding pellets are heated to 70-98° C. and dried for 2-8 hours before rotomoulding.

[0016] Optionally, in S1, the rotomoulding temperature is 70 to 90° C., and the rotomoulding time is 4 to 10 hours.

[0017] Optionally, in S1, after the inner liner is prepared, it is inflated to 0.4-0.8 MPa and a sealing test is performed.

[0018] Optionally, in S2, the winding tension is set to 20-80N and the winding angle is set to 0-85°.

[0019] Optionally, in S2, the laser heating position is located on the reinforcing fiber prepreg tape, and the laser heating temperature is 230-300°C.

[0020] Optionally, in S2, the laser heating path is the same as the winding path of the reinforced fiber prepreg tape, and the width of the heating area covers the width of the fiber reinforced prepreg tape.

[0021] Optionally, in S2, parameters such as temperature and speed of the prepreg tape are detected in real time.

[0022] Optionally, the method further includes step S4, post-processing and detection.

[0023] Optionally, in S4, the appearance and dimensions of the air cylinder are inspected.

[0024] Optionally, in S4, the air cylinder is pressure tested.

[0025] The beneficial effects of the present invention are:

[0026] 1. In the fiber-reinforced air cylinder provided by the present invention, the air cylinder liner and the winding layer matrix are made of the same thermoplastic material and can be melted into one during the preparation process, so there is no stratification problem. The air cylinder liner and the winding layer are layered without an interface, so that the liner layer and the winding layer have a high bonding strength, which extends the service life and does not use adhesives. The air cylinder has high strength, light weight, corrosion resistance, wear resistance, good thermal stability and excellent sealing performance. Compared with traditional stainless steel air cylinders, it is more than 40% lighter and has the advantages of acid and alkali resistance and salt spray corrosion resistance.

[0027] 2. The preparation method of the fiber reinforced air cylinder provided by the present invention innovatively adopts rotational molding + robotic arm infrared heating winding process. During the winding process, the reinforced fiber prepreg tape and the air cylinder inner liner are melted into one, avoiding stratification between the inner liner and the winding layer, and the heating path is the same as the winding path of the reinforced fiber prepreg tape, so that the prepreg tape in the winding layer is melted layer by layer, avoiding defects such as bubbles inside the winding layer, and significantly improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 This is a schematic diagram of the structure of the fiber-reinforced air cylinder in Example 1.

[0030] Figure 2 This is a cross-sectional view of the fiber-reinforced air cylinder during the preparation process in Example 1.

[0031] Among them, 1. fiber reinforced air cylinder; 2. winding layer 2; 3. liner; 4. reinforced fiber prepreg tape; 5. laser heating position. DETAILED DESCRIPTION

[0032] 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.

[0033] 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.

[0034] Example 1

[0035] like Figure 1 As shown, a fiber reinforced air cylinder 1 includes: an inner liner 3 and a winding layer 2; the inner liner 3 is made of thermoplastic nylon PA6 (polyamide 6), the raw material of the winding layer 2 is a reinforcing fiber prepreg tape 4, the matrix of the reinforcing fiber prepreg tape 4 is thermoplastic nylon PA6, and the inner liner 3 and the winding layer 2 are made of the same thermoplastic nylon material and are fused together.

[0036] The reinforcing fibers are carbon fibers, and the reinforcing fibers are arranged in a set winding direction.

[0037] In the above configuration, the inner liner 3 of the air cylinder and the matrix of the winding layer 2 are made of the same thermoplastic material and are melted into one. Therefore, the cylinder wall of the fiber-reinforced air cylinder 1 is made of PA6. Inside the cylinder wall, the distribution density of the reinforcing fibers varies with the thickness range: there is no reinforcing fiber in the inner part, and the reinforcing fibers in the outer part are dispersed in the PA6 matrix according to the winding direction. Since the layered structure is eliminated, the problem of short service life caused by the layering problem is avoided.

[0038] The preparation method is implemented based on a robot displacement system. The laser transmitter is fixed on a robotic arm, and the reinforcing fiber prepreg tape 4 is fed along the robotic arm. The laser directly heats the reinforcing fiber prepreg tape 4 mounted on the robotic arm, and the heated prepreg tape is wound along the inner liner 3 at a certain winding angle.

[0039] The method for preparing the fiber-reinforced air cylinder 1 of this embodiment comprises the following steps:

[0040] S1. Use PA6 rotomolding granules as raw material, dry them in an oven at 70℃ for 2h, weigh 3kg of the dried PA6 rotomolding granules and add them to the rotomolding mold, set the main shaft speed of the electric heating rotomolding equipment to 2.0rpm, the secondary shaft speed to 1.9rpm, the rotomolding temperature to 70℃, and ensure uniform heating; the rotomolding time is 4h, take out the inner liner 3 after cooling, and measure the wall thickness to be 3mm. Inflate the inner liner 3 with 0.4MPa to test its sealing performance. The rotomolding temperature of 70~90℃ is the melting point of PA66, and the granules can be melted into liquid molding in the mold.

[0041] S2. Wrap the reinforcing fiber prepreg 4 on the outside of the inner liner 3 that has passed the test according to the set winding direction. The reinforcing fiber prepreg 4 is a prepreg with a volume content of 55% of carbon fiber (the matrix accounts for 45% of the volume of the prepreg), the matrix of the prepreg is PA6, the winding tension is set to 40N, the winding angle is 75-85°, and different winding angles are set at different positions of the air cylinder; during the winding process, the reinforcing fiber prepreg 4 wrapped on the air cylinder is heated to 250±20°C by laser. Laser heating can make the thermoplastic prepreg of the wrapping layer 2 reach a temperature of 230-300°C in an instant, which is lower than the pyrolysis temperature, and the prepreg matrix melts quickly and is combined with the carbon fiber by viscosity. The winding tension is also mainly borne by the carbon fiber, so that the prepreg can be easily laid. The phenomenon is that the reinforcing fiber prepreg 4 melts on the surface of the inner liner 3, and melts into one with the inner liner 3 or the prepreg that has been melted into one on the inner liner 3, and stops when the thickness of the wrapping layer 2 is 4mm, and the whole wind cylinder that has been wound is obtained.

[0042] S3. Secondarily cure the wound air cylinder as a whole at 90° C. for 2 hours to obtain a fiber-reinforced air cylinder 1 product.

[0043] S4. During post-processing and testing, first check the appearance and dimensions of the air cylinder, and then perform a pressure test on the air cylinder if it passes the test.

[0044] Among them, in S2, Figure 2 As shown, the laser heating position 5 is located outside the inner liner 3, and the multiple layers of reinforcing fiber prepreg tapes 4 are first melted and then wound around the outer side of the inner liner 3 to form a winding layer 2; under the extrusion of the winding tension, the matrix of the reinforcing fiber prepreg tape 4 is tightly connected to the inner liner 3, thereby achieving the effect of eliminating interlayer defects in the winding layer 2; the laser heating path is the same as the winding path of the reinforcing fiber prepreg tape 4, and the heating area of ​​the laser heating position 5 covers the width of the reinforcing fiber prepreg tape 4.

[0045] In the preparation method of the fiber-reinforced air cylinder 1, the accessories of the air cylinder interface located at both ends of the air cylinder are installed and integrated with the inner liner 3 during the process of rotational molding of the inner liner 3, and the winding process in S2 further reinforces the air cylinder interface.

[0046] Example 2

[0047] A fiber reinforced air cylinder 1 comprises: an inner liner 3 and a winding layer 2; the inner liner 3 is made of thermoplastic nylon PA66 (polyamide 66), the raw material of the winding layer 2 is a reinforcing fiber prepreg tape 4, the matrix of the reinforcing fiber prepreg tape 4 is thermoplastic nylon PA66, the inner liner 3 and the winding layer 2 are made of the same thermoplastic nylon material and are fused together, the winding layer 2 comprises two layers, the inner winding layer is made of carbon fiber reinforced nylon PA66 prepreg tape, and the outer winding layer is made of glass fiber reinforced nylon PA66 prepreg tape.

[0048] The reinforcing fibers are carbon fibers and glass fibers, and the reinforcing fibers are arranged in a set winding direction.

[0049] The method for preparing the fiber-reinforced air cylinder 1 of this embodiment comprises the following steps:

[0050] S1. Use PA66 rotomolding pellets as raw materials, dry them in an oven at 98°C for 8h, weigh 5kg of the dried PA66 rotomolding pellets and add them to the rotomolding mold, set the main shaft speed of the electric heating rotomolding equipment to 7.0rpm, the secondary shaft speed to 5.0rpm, the rotomolding temperature to 90°C, and heat evenly; the rotomolding time is 10h, and after cooling, take out the liner 3, and measure the wall thickness to be 6mm. Inflate the liner 3 to 0.8MPa to test its sealing performance;

[0051] S2. Wind the reinforcing fiber prepreg tape 4 on the outside of the inner liner 3 that has passed the test according to the set winding direction. The first thing to be wound is the carbon fiber reinforced PA66 prepreg tape with a carbon fiber content of 55% and 5 layers. Secondly, the outermost layer is the glass fiber reinforced PA66 prepreg tape, which is wound in 2 layers. The matrix of the prepreg tape is PA66, and the winding tension is set to 80N and the winding angle is 85°. During the winding process, the laser is used to heat the reinforcing fiber prepreg tape 4 wound on the air cylinder to 300°C. The phenomenon is that after the matrix is ​​melted, the reinforcing fiber prepreg tape 4 is squeezed on the inner liner 3 by the winding tension borne by the carbon fiber and glass fiber, and is melted into one with the inner liner 3 or the prepreg tape that has been melted into one on the inner liner 3, and stops when the thickness of the winding layer 2 is 6mm. Since the matrix has been melted before contacting the inner liner 3, it can penetrate into the reinforcing fiber and fit tightly with the surface of the inner liner 3, thereby obtaining a well-wound air cylinder as a whole.

[0052] S3. Secondarily cure the wound air cylinder as a whole at 70° C. for 5 hours to obtain a fiber-reinforced air cylinder 1 product.

[0053] Among them, in S2, as in Example 1, the laser heating position 5 is located outside the inner liner 3, and the multiple layers of reinforcing fiber prepreg tape 4 are melted into a winding layer 2; the laser heating path is the same as the winding path of the reinforcing fiber prepreg tape 4, and the heating area width of the laser heating position 5 covers the width of the reinforcing fiber prepreg tape 4.

[0054] Specifically, the operation steps and key points of this process include:

[0055] 1. Fix the inner liner 3 on the winding machine and set the winding parameters, such as winding speed, tension, winding angle, etc.

[0056] 2. Fix one end of the reinforcing fiber prepreg tape 4 on the winding machine to ensure that it maintains a constant tension during the winding process.

[0057] 3. Start the winding machine to start winding the reinforcing fiber prepreg tape 4 along the surface of the inner liner 3.

[0058] 4. At the same time, the laser heating system is started, and the laser beam is scanned along the moving direction of the prepreg tape to heat the reinforcing fiber prepreg tape 4 in real time.

[0059] 5. Laser heating causes the resin in the reinforcing fiber prepreg tape 4 to melt and penetrate into the reinforcing fibers, closely fitting with the surface of the liner 3.

[0060] 6. During the winding process, the laser heating effect and the winding quality of the reinforcing fiber prepreg tape 4 are monitored in real time to ensure that the resin is fully melted and evenly distributed.

[0061] 7. After winding to the designed number of layers or thickness, turn off the laser heating system.

[0062] 8. Continue to wind several layers of unheated reinforcing fiber prepreg tape 4 to protect the internal structure and improve the overall performance of the air cylinder.

[0063] 9. After winding is completed, allow the cylinder to cool naturally at room temperature, or cool and solidify under controlled conditions.

[0064] 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 fiber-reinforced air cylinder, characterized in that: including an inner liner and a winding layer 2; The raw material of the inner liner is thermoplastic nylon, the raw material of the winding layer 2 is reinforcing fiber prepreg tape, the matrix of the reinforcing fiber prepreg tape is thermoplastic nylon, and the inner liner and the winding layer 2 are made of the same thermoplastic nylon material and are melted into one.

2. The fiber-reinforced air cylinder according to claim 1, characterized in that: The thermoplastic nylon is PA6 or PA66, and the reinforcing fiber is carbon fiber and / or glass fiber; Optionally, the reinforcing fibers in the winding layer 2 are arranged according to a set winding direction.

3. A method for preparing a fiber-reinforced air cylinder as claimed in claim 1 or 2, characterized in that: Includes steps: S1, preparing the liner by rotational molding; S2. Wind the reinforcing fiber prepreg tape on the outside of the inner tank according to the set winding direction. During the winding process, use laser to heat the reinforcing fiber prepreg tape wound on the air cylinder to 250-300°C. S3. The wound air cylinder is subjected to secondary curing at 70-90° C. to obtain a fiber-reinforced air cylinder product.

4. The method for preparing a fiber-reinforced air cylinder according to claim 3, characterized in that: In S1, the rotomoulding pellets are heated to 70-98°C and dried for 2-8 hours before rotomoulding.

5. The method for preparing a fiber-reinforced air cylinder according to claim 3, characterized in that: In S1, the rotomoulding temperature is 70-90°C and the rotomoulding time is 4-10 hours.

6. The method for preparing a fiber-reinforced air cylinder according to claim 3, characterized in that: In S1, after the inner liner is prepared, it is inflated to 0.4-0.8 MPa and a sealing test is performed.

7. The method for preparing a fiber-reinforced air cylinder according to claim 3, characterized in that: In S1, the protruding structures of the two end joints are separated from the inner surface of the rotational molding mold by a set distance.

8. The method for preparing a fiber-reinforced air cylinder according to claim 3, characterized in that: In S2, the winding tension is set to 20 to 80 N and the winding angle is set to 0 to 85°.

9. The method for preparing a fiber-reinforced air cylinder according to claim 1, characterized in that: In S2, the laser heating position is located on the thermoplastic prepreg tape, and the laser heating temperature is 230-300°C; Optionally, the laser heating path is the same as the winding path of the reinforcing fiber prepreg tape, and the width of the heating area covers the width of the reinforcing fiber prepreg tape.

10. The method for preparing a fiber-reinforced air cylinder according to claim 1, characterized in that: It also includes step S4, post-processing and detection; Optionally, in S4, the appearance and dimensions of the air cylinder are inspected; Optionally, in S4, the air cylinder is pressure tested.

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