CN110815867A - Simple flexible pressure equalizing pad for hot press molding of composite material and application thereof - Google Patents

Abstract

The invention discloses a simple flexible pressure-equalizing pad for hot-press molding of a composite material and application thereof, wherein the simple flexible pressure-equalizing pad comprises a demolding cloth layer and a fiber cloth layer, and the demolding cloth layer is paved on the fiber cloth layer; the simple flexible pressure equalizing pad is mainly used for assisting the autoclave molding process of the composite material part. Compared with the traditional pressure pad, the simple flexible pressure equalizing pad has the advantages of simple structure, low manufacturing cost and short preparation period, and the flexibility of the simple flexible pressure equalizing pad is better than that of the pressure pad, so that the simple flexible pressure equalizing pad is well matched with a composite material part in the auxiliary forming process, and the surface smoothness of the formed composite material part is better ensured.

Description

A simple and flexible pressure equalizing pad for hot pressing of composite materials and its application

technical field

The invention relates to a simple and flexible pressure equalizing pad used for hot pressing of composite materials and its application.

Background technique

Resin-based carbon fiber composites have superior properties such as high specific strength and specific stiffness, strong designability, good fatigue fracture resistance, corrosion resistance, and good dimensional stability. They are currently widely used in aviation, aerospace, transportation and other fields. High performance structural material. Among a variety of carbon fiber composite material forming processes, the autoclave process has uniform forming temperature and pressure, and has good adaptability to parts of different materials, shapes, sizes and structures, so it has become a research and manufacturing aerospace high-quality composite material. One of the main process methods of material components.

When using the autoclave process to form composite parts, due to the high pressure in the autoclave, the folds and textures of auxiliary materials such as vacuum bags and air felt will inevitably be reflected on the forming surface of the parts. Therefore, metal or Rubber pressure pads are used for auxiliary molding to ensure that the surface of the parts is smooth and flat, and meets the requirements for the surface of parts assembly.

At present, the auxiliary molding pressure pad of composite parts is prepared by the co-curing process of rubber and glass fiber. The preparation process is relatively complicated, the preparation cycle is long and the cost is high, and the flexibility of the pressure pad is poor. For flat composite parts, look for pressure pads that do not require curing and are flexible and can replace traditional pressure pads. However, the use of metal or rubber pressure pads mainly has the following problems: (1) The metal pressure pads cost less, but they need to be preformed, and the conformability is relatively poor. It is easy to deform and scratch during storage, resulting in parts Uneven pressure during curing, or locally rich resin, surface damage, etc.; (2) When manufacturing rubber pressure pads, it is necessary to manufacture pressure pad molding tooling, and use rubber and internal reinforcing fibers to cure corresponding profiles, with good conformability , but the cost is high, the manufacturing process is complicated, and the rubber is easily oxidized at high temperature, and there are problems such as deformation and surface damage after multiple feedings, which affect the quality of the parts and can be reused less frequently. Therefore, when using the traditional pressure pad solution to manufacture parts, the preparation process is relatively complicated, the preparation cycle is long, the cost is high, and the later maintenance is inconvenient. These shortcomings are especially obvious when manufacturing simple flat or curved parts.

SUMMARY OF THE INVENTION

In order to overcome the shortcomings of the above-mentioned traditional pressure pads, the present invention provides a simple and flexible pressure equalizing pad for composite material autoclave forming process, which is light in weight, not easily deformed, and can provide uniform pressure when the parts are cured, and It can prevent the fiber cloth from absorbing resin and affecting the thickness of the parts. The specific technical solutions are as follows:

First of all, the present invention provides a simple and flexible pressure-equalizing pad for thermocompression molding of composite materials. The simple and flexible pressure-equalizing pad includes a release cloth layer and a fiber cloth layer, and the release cloth layer is laid on the fiber cloth layer to form Simple and flexible equalizing pad.

In the aforementioned simple and flexible pressure-equalizing pad for composite material thermoforming, the release cloth layer is a PTFE release cloth with glue on one side, and the glued surface is laid on the fiber cloth layer.

In the aforementioned simple and flexible pressure-equalizing pad for thermocompression molding of composite materials, the fiber cloth layer is made of dry polyester peelable cloth.

Secondly, the present invention also provides a composite material hot pressing forming device containing the aforementioned simple flexible pressure equalizing pad, the device comprising a simple flexible pressure equalizing pad, a composite material part forming mold bottom plate and a sealing material; the composite material part forming mold bottom plate A composite material pre-formed part is placed on it, and the simple flexible pressure equalizing pad is pressed on the composite material pre-formed part; the sealing material includes a vacuum bag and a sealing tape, and the vacuum bag is covered on the simple flexible pressure equalizing pad, so The sealing strip attaches the vacuum bag to the bottom plate of the composite material part forming mold around the composite material pre-formed part.

In addition, the present invention also provides a method for using the aforementioned simple and flexible pressure equalizing pad, comprising the following steps:

1) Covering the pressure equalizing pad: Cover the preformed parts of the composite material with one side of the demoulding cloth of the aforementioned simple flexible pressure equalizing pad facing down;

2) Cut and splicing: according to the profile and size of the composite preformed parts, the simple flexible pressure equalizing pad described in step 1) is notched and spliced to ensure that the simple flexible pressure equalizing pad can completely cover the composite material preformed parts s surface;

3) Encapsulation: encapsulate the composite material pre-formed part and the simple flexible pressure equalizing pad in step 2) together, and tightly fit the simple flexible pressure equalizing pad on the surface of the composite material pre-formed part;

4) Curing and forming: The composite preformed parts packaged in step 3) are sent to the autoclave together with the simple flexible pressure equalizing pad for hot pressing, so that the composite preformed parts are solidified and formed. The formed composite material part can be obtained after the flexible pressure equalizing pad is removed from the mold.

As a preferred technical solution, in step 2), the splicing is performed by using a pressure-sensitive adhesive tape for splicing and fixing.

As a preferred technical solution, in step 3), the encapsulation is to use a vacuum bag and a sealing tape to vacuum encapsulate the simple flexible pressure equalizing pad and the composite material pre-formed part on the bottom plate of the composite material part forming mold, and seal the package. Air-conducting material is applied to the front.

The beneficial effects of the present invention are:

Compared with the traditional pressure pad, the simple and flexible pressure-equalizing pad of the present invention has the advantages of simple structure, low production cost and short preparation period, and the simple and flexible pressure-equalizing pad of the present invention is more flexible than the pressure pad, and matches with the composite material parts in the auxiliary molding process. Good quality, better ensure the surface smoothness of composite parts after molding.

Description of drawings

1 is a schematic structural diagram of a simple and flexible pressure equalizing pad of the present invention;

FIG. 2 is a schematic diagram of the packaging structure of a simple flexible pressure equalizing pad and a composite material part according to the present invention.

In the figure: 1. Release cloth layer; 2. Fiber cloth layer; 3. Simple and flexible pressure equalizing pad; 4. Composite material preformed parts; 5. Vacuum bag; 6. Sealing strip; 7. Composite material parts forming mold Bottom plate; 8. Air guide material.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on this embodiment, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

This embodiment is a simple and flexible pressure equalizing pad used for hot pressing of composite materials, as shown in FIG. 1 , including a release cloth layer 1 and a fiber cloth layer 2, and the release cloth layer 1 is laid on the fiber cloth layer. A simple flexible equalizing pad 3 is formed on the 2. Wherein, the release cloth layer 1 is a single-sided adhesive PTFE release cloth, and its adhesive surface is laid on the fiber cloth layer 2; the fiber cloth used in the fiber cloth layer 2 is dry polyester peelable cloth. In some embodiments, a separate polyester peelable cloth can be used to directly cover the prepreg of the composite part, but because it is easy to absorb resin, the thickness of the molded part becomes thinner, which reduces the thickness of the composite part. In this implementation, a layer of PTFE release cloth is added to the side of the dry polyester peelable cloth in contact with the composite material prepreg, which effectively solves this problem and ensures that the surface of the part is smooth and smooth.

When making the simple flexible pressure equalizing pad for composite material thermoforming described in this embodiment, firstly cut out a fiber cloth slightly larger than the size of the part according to the size of the composite material part. If the width of the fiber cloth is smaller than that of the part, then Multiple pieces of fiber cloth can be cut to ensure that the fiber cloth can completely cover the surface of the part, and a layer of demoulding cloth is laid on one side of the fiber cloth. Pay attention to eliminating wrinkles when laying, and the aforementioned pressure equalizing pad can be prepared.

When using the simple flexible pressure equalizing pad for composite material hot pressing, the device includes a simple flexible pressure equalizing pad 3, a composite part forming mold bottom plate 7 and a sealing material; the composite material part forming mold bottom plate 7 is placed on the composite material part. The material preformed part 4, the simple flexible pressure equalizing pad 3 is pressed on the composite material preformed part 4; the sealing material includes a vacuum bag 5 and a sealing strip 6, and the vacuum bag 5 is covered on the simple flexible pressure equalizing pad 3, the sealing strip 6 attaches the vacuum bag 5 to the composite material part forming mold base plate 7 around the composite material preformed part 4, so that the simple and flexible pressure equalizing pad 3 compacts the composite material preformed part 4, The two are packaged on the bottom plate 7 of the composite part forming mold.

Example 2

This embodiment provides an application of the simple and flexible pressure equalizing pad described in Embodiment 1, which is mainly used to assist the forming process of the autoclave of composite parts, including the following steps:

1) Covering the pressure-equalizing pad: the release cloth layer 1 of the simple flexible pressure-equalizing pad 3 described in Example 1 is laid down and covered on the composite material preformed part 4;

2) Cut and splicing: According to the profile and size of the composite material pre-formed part 4, cut the simple flexible pressure equalizing pad 3 described in step 1 at the corner of the part, the curvature change area, etc., and use pressure-sensitive tape for splicing fixed to ensure that the simple flexible pressure equalizing pad 3 can completely cover the surface of the composite material preformed part 4;

3) Packaging: use the vacuum bag 5 and the sealing tape 6 to package the composite material pre-formed part 4 and the simple flexible pressure equalizing pad 3 in step 2 together on the composite material part forming mold base plate 7, as shown in Figure 2; at the same time; The simple flexible pressure equalizing pad 3 is closely attached to the surface of the composite material preformed part 4 . In some embodiments, another layer of polyester fiber air-conducting felt can be applied as the air-conducting material 8 before packaging, so that the product can be discharged during the curing process of the volatile gas generated inside and the residual air between the layers to ensure the manufacturing process. product quality of the piece.

4) Curing and forming: The composite material pre-formed part 4 packaged in step 3 is sent to the autoclave together with the simple flexible pressure equalizing pad 3 for hot pressing, so that the composite material pre-formed part 4 is solidified and formed. The formed composite material part can be obtained after the simple flexible pressure equalizing pad 3 is removed and demolded.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. In addition, it should be understood that what is described above is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms. Any person skilled in the art may make changes or modifications by using the technical content disclosed above. are equivalent embodiments with equivalent variations. However, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still belong to the protection scope of the technical solutions of the present invention.

Claims (7)

1. A simple and flexible pressure-equalizing pad for thermocompression molding of composite materials, characterized in that it comprises a release cloth layer (1) and a fiber cloth layer (2), and the release cloth layer (1) is laid on the A simple and flexible pressure equalizing pad (3) is formed on the fiber cloth layer (2). 2 . The simple and flexible pressure equalizing pad for composite material thermoforming according to claim 1 , wherein the release cloth layer ( 1 ) is a PTFE release cloth with glue on one side, and the release cloth is glued. 3 . The surface is pasted on the fiber cloth layer (2). 3 . The simple and flexible pressure equalizing pad for composite material thermoforming according to claim 1 , wherein the fiber cloth layer ( 2 ) is made of dry polyester peelable cloth. 4 . 4. A composite material hot-pressing molding device containing the simple and flexible pressure equalizing pad according to claims 1 to 3, characterized in that it comprises a simple flexible pressure equalizing pad (3), a composite material part forming mold base plate (7) and a seal materials; a composite material preformed part (4) is placed on the bottom plate (7) of the composite material part forming mold, and the simple and flexible pressure equalizing pad (3) is pressed on the composite material preformed part (4); the sealing The material includes a vacuum bag (5) and a sealing strip (6), the vacuum bag (5) is covered on the simple and flexible pressure equalizing pad (3), and the sealing strip (6) attaches the vacuum bag (5) On the base plate (7) of the composite part forming mold around the composite preform part (4). 5. An application of the simple and flexible pressure equalizing pad according to claims 1 to 3, characterized in that: comprising the following steps: 1) Covering the pressure-equalizing pad: the simple flexible pressure-equalizing pad (3) according to claims 1 to 3 is covered with one side of the release cloth facing down on the composite material preformed part (4); 2) Cut and splicing: according to the profile and size of the composite material preformed part (4), the simple flexible pressure equalizing pad (3) described in step 1) is notched and spliced to ensure the simple flexible pressure equalizing pad (3). ) can completely cover the surface of the composite preformed part (4); 3) Encapsulation: The composite material preformed part (4) and the simple flexible pressure equalizing pad (3) in step 2) are packaged together, and the simple flexible pressure equalizing pad (3) is closely attached to the composite material preformed part (4). )s surface; 4) Curing and forming: The composite material pre-formed part (4) packaged in step 3) is sent to the autoclave together with the simple flexible pressure equalizing pad (3) for hot pressing, so that the composite material pre-formed part (4) is cured After molding, after the tank is cooled, the simple flexible pressure equalizing pad (3) is uncovered and demolded to obtain a molded composite material part. 6 . The application of the simple and flexible pressure equalizing pad according to claim 5 , wherein in step 2), the splicing is performed by using pressure-sensitive adhesive tape for splicing and fixing. 7 . 7. The application of the simple and flexible pressure-equalizing pad according to claim 5, characterized in that: in step 3), the encapsulation is to use a vacuum bag (5) and a sealing tape (6) to combine the simple and flexible pressure-equalizing pad ( 3) and the composite material pre-formed part (4) are vacuum-sealed on the composite material part forming mold bottom plate (7), and the air-conducting material is laid before the packaging.

Images