A method of forming by extending the length of the transition zone to reduce heat-seal membrane creasing

Abstract

The application discloses a forming method for reducing thermal diaphragm wrinkles by prolonging the length of a transition area, which comprises the following steps: S1: after automatic tape laying is completed, a layer of non-porous isolation film is placed on a prepreg blank, vacuum pre-compaction is performed for about 15 min, and the transition area is made more obvious; S2: according to the thickness of the transition area of a part and the layer loss ratio, a blanking program is made in combination with the size of the part blank, and waste prepreg is used for blanking; S3: according to the thickness of the transition area and the layer loss ratio, waste prepreg is used to be laid along the transition area on the blank, and the waste and the blank are butt-jointed to prolong the transition area and enlarge the layer loss ratio; S4: vacuum pre-compaction is performed for about 15 min, so that the waste and the prepreg blank are closely attached, and non-porous isolation film is used to separate the waste and the prepreg blank; and S5: the well-compacted prepreg blank is sent into a thermal diaphragm machine to perform diaphragm forming.

Description

Technical Field

[0001] This invention relates to the field of thermal diaphragm molding technology for aerospace composite materials, and specifically to a molding method that reduces thermal diaphragm wrinkles by extending the length of the transition zone. Background Technology

[0002] The thermal diaphragm process involves placing a prepreg sheet laid by hand or automatically between two layers of highly ductile diaphragms and transferring it as a whole onto a thermal diaphragm machine. The sheet is then pressed into a preform of a complex shape using vacuum negative pressure and infrared heating. This process offers high production speed, high molding quality, and good stability, and has become an important low-cost manufacturing technology. It is widely used both domestically and internationally in the manufacturing of aerospace composite material parts.

[0003] When using thermal diaphragm technology to manufacture thick composite parts, the diaphragm covers the prepreg blank. Due to the uneven thickness of the prepreg blank, the diaphragm will cause lateral compression in the transition zone, resulting in large longitudinal wrinkles in the flat blank in the transition zone, which affects the surface quality of the part. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a forming method to reduce thermal diaphragm wrinkles by extending the length of the transition zone. The method uses prepreg to smooth the transition zone steps according to the thickness and the loss ratio. By increasing the loss ratio of the transition zone, the lateral extrusion of the diaphragm on the transition zone is reduced, thereby greatly reducing or completely eliminating the occurrence of wrinkles and improving the surface quality of the part.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A molding method for reducing thermal diaphragm wrinkles by extending the length of the transition zone includes the following steps:

[0007] Step S1: After automatic tape laying is completed, place a non-porous release film on the prepreg blank and vacuum pre-compact it for about 15 minutes to make the transition zone more obvious.

[0008] Step S2: Based on the thickness of the transition zone and the delamination ratio of the part, and in conjunction with the size of the part blank, create a blanking program and use scrap / expired prepreg for blanking;

[0009] Step S3: Based on the thickness of the transition zone and the delamination ratio, use waste prepreg to lay on the blank along the transition zone, and use waste to butt joint with the blank to extend the transition zone and increase the delamination ratio;

[0010] Step S4: Vacuum pre-compact for about 15 minutes to ensure that the waste material and the prepreg blank are tightly bonded together, and a non-porous release membrane is used to separate the two.

[0011] Step S5: The compacted prepreg blank is fed into the heat diaphragm machine for diaphragm separation.

[0012] Furthermore, the specific parameters for extending the transition zone are as follows: the angle between the first line connecting the upper right end of the first layer of blank and the upper right end of the bottom layer of blank and the horizontal plane / horizontal line is α; the angle between the second line connecting the upper right end of the first layer of waste and the upper right end of the bottom layer of waste and the horizontal plane / horizontal line is β, b / a = 0.05-0.25; the bottom layer of blank has a length L1, and the bottom layer of waste has a length L2, L1 / L2 = 0.1-0.3.

[0013] Furthermore, the included angle b / a = 0.14-0.15, and the length L1 / L2 = 0.18-0.2.

[0014] The present invention provides a molding method for reducing thermal diaphragm wrinkles by extending the length of the transition zone. The method uses prepreg to smooth the transition zone steps according to the thickness and the layer loss ratio. By increasing the layer loss ratio in the transition zone, the lateral compression of the diaphragm on the transition zone is reduced, thereby greatly reducing or completely eliminating the occurrence of wrinkles and improving the surface quality of the part. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the stress analysis of the cause of wrinkles in the thermal diaphragm of the present invention;

[0016] Figure 2 This is a comparative schematic diagram of the extended transition region of the present invention;

[0017] Figure 3 This is a schematic diagram showing the effect before the transition zone is extended in this invention;

[0018] Figure 4 This is a schematic diagram illustrating the effect of extending the transition region in this invention. Detailed Implementation

[0019] To make the technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of the present invention, and are only used to explain the present invention, not to limit the present invention. It should be noted that, for ease of description, only the parts / structures related to the present invention are shown in the accompanying drawings. Other related parts can be referred to with ordinary design. In the absence of conflict, the embodiments and technical features in the embodiments of the present invention can be combined with each other to obtain new embodiments.

[0020] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Furthermore, unless otherwise defined, the technical or scientific terms used in the description of this invention should have the ordinary meaning understood by those skilled in the art.

[0021] The present invention will now be described in further detail with reference to the accompanying drawings.

[0022] like Figure 1-4 As shown, a molding method for reducing thermal diaphragm wrinkles by extending the length of the transition zone includes the following steps:

[0023] Step S1: After automatic tape laying is completed, place a non-porous release film on the prepreg blank and vacuum pre-compact it for about 15 minutes to make the transition zone more obvious.

[0024] Step S2: Based on the thickness of the transition zone and the delamination ratio of the part, and in conjunction with the size of the part blank, create a blanking program and use prepreg (scrap / expired prepreg) for blanking;

[0025] Step S3: Based on the transition zone thickness and delamination ratio, use waste prepreg to lay on the blank along the transition zone, and use waste to butt joint with the blank to extend the transition zone and increase the delamination ratio, such as... Figure 2 As shown;

[0026] Step S4: Vacuum pre-compact for about 15 minutes to ensure that the waste material and the prepreg blank are tightly bonded together, and a non-porous release membrane is used to separate the two.

[0027] Step S5: The compacted prepreg blank is fed into the heat diaphragm machine for diaphragm separation.

[0028] In step S3, the specific parameters for extending the transition zone are as follows: the angle between the first line connecting the upper right end of the first layer of blank and the upper right end of the bottom layer of blank and the horizontal plane / horizontal line is α; the angle between the second line connecting the upper right end of the first layer of waste and the upper right end of the bottom layer of waste and the horizontal plane / horizontal line is β; b / a = 0.1-0.2, preferably 0.14-0.15; the bottom layer of blank has a length L1, and the bottom layer of waste has a length L2; L1 / L2 = 0.13-0.23, preferably 0.18-0.19.

[0029] like Figure 1 As shown, the diaphragm will generate lateral compression in the transition zone, resulting in large longitudinal wrinkles in the flat sheet in the transition zone.

[0030] like Figure 2As shown, prepreg is used to fill the transition zone steps according to the thickness and the loss ratio. By increasing the loss ratio of the transition zone (the specific parameters for extending the transition zone are: b / a = 0.1-0.2, preferably 0.14-0.15; L1 / L2 = 0.13-0.23, preferably 0.18-0.19), the lateral compression of the diaphragm on the transition zone is reduced, thereby greatly reducing or completely eliminating the occurrence of wrinkles and improving the surface quality of the part.

[0031] The present invention provides a molding method for reducing thermal diaphragm wrinkles by extending the length of the transition zone. The method uses prepreg to smooth the transition zone steps according to the thickness and the layer loss ratio. By increasing the layer loss ratio in the transition zone, the lateral compression of the diaphragm on the transition zone is reduced, thereby greatly reducing or completely eliminating the occurrence of wrinkles and improving the surface quality of the part.

[0032] The above embodiments are illustrative of the present invention and not intended to limit the invention. It is understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A molding method for reducing thermal diaphragm wrinkles by extending the length of the transition zone, comprising the following steps: Step S1: After automatic tape laying is completed, place a non-porous release film on the prepreg blank and vacuum pre-compact it for about 15 minutes to make the transition zone more obvious. Step S2: Based on the thickness of the transition zone and the depletion ratio of the part, and in conjunction with the size of the part blank, create a blanking program and use scrap / expired prepreg for blanking; Step S3: Based on the thickness of the transition zone and the delamination ratio, use waste prepreg to lay on the blank along the transition zone, and use waste to connect with the blank to extend the transition zone and increase the delamination ratio; Step S4: Vacuum pre-compact for about 15 minutes to ensure that the waste material and the prepreg blank are tightly bonded together, and a non-porous release membrane is used to separate the two. Step S5: The compacted prepreg blank is fed into a heat-sealing machine for diaphragm sealing. The specific parameters for extending the transition zone are as follows: the angle between the first line connecting the upper right end of the first layer of blank and the upper right end of the bottom layer of blank and the horizontal plane / horizontal line is α; the angle between the second line connecting the upper right end of the first layer of waste and the upper right end of the bottom layer of waste and the horizontal plane / horizontal line is β; b / a = 0.05-0.25; the bottom layer of blank has a length L1; the bottom layer of waste has a length L2; L1 / L2 = 0.1-0.

3.

2. The molding method for reducing thermal insulation film wrinkles by extending the length of the transition zone as described in claim 1, characterized in that, The included angle b / a = 0.14-0.15, and the length L1 / L2 = 0.18-0.2.

Images