A one-step injection molding process for a composite sandwich structure

Abstract

The application discloses a kind of composite sandwich structure disposable injection molding processes, comprising the following steps: sandwich layer processing, layer, injection and heat preservation forming, first the foaming forming of sandwich layer is carried out, obtains the foaming sandwich board of plane or curved surface structure, and processes or is obtained several through holes by foaming forming on the foaming sandwich board, fills foaming plastic column in through hole, is wrapped with flow guide cloth cover on the surface of foaming plastic column, obtains sandwich layer.By the above mode, the composite sandwich structure disposable injection molding process of the application can be integrally formed by one-time injection, has high production efficiency, forms multiple flow guide channels by flow guide cloth cover, connects the resin on the upper and lower surfaces of sandwich layer, reduces the hole and other interface defect problems, improves the integrity and stability of structure.

Description

Technical Field

[0001] This invention relates to the field of resin injection, and in particular to a one-time injection molding process for a composite sandwich structure. Background Technology

[0002] To improve the heat insulation and sound insulation of composite materials, a foam sandwich structure can be used, with the foamed sandwich panel in the middle providing heat insulation and sound absorption.

[0003] In the molding process of foam sandwich structures, the foamed sandwich panel and the fiber cloth are bonded together with resin. If the molding is done in a single injection molding process, voids and defects can easily form between the foamed sandwich panel and the fiber cloth, compromising structural stability. Patent application number 201410264905.X discloses a method for resin injection pretreatment of foam material in the molding of composite foam sandwich structures. By pretreatment of the foam with resin before bonding it to the fiber panel, the problem of interface defects is solved. However, this additional pretreatment step significantly increases the production cycle and cost. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a one-time injection molding process for composite sandwich structures, which achieves one-time injection molding and improves structural stability.

[0005] To solve the above-mentioned technical problems, one technical solution adopted by the present invention is to provide a one-time injection molding process for a composite sandwich structure, comprising the following steps:

[0006] A. Processing of the sandwich layer: The sandwich layer is foamed to obtain a foamed sandwich panel with a planar or curved structure. Several through holes are processed on the foamed sandwich panel or obtained through foaming. Foamed plastic columns are filled into the through holes. A flow guide cloth is wrapped around the surface of the foamed plastic columns to obtain the sandwich layer.

[0007] B. Laying out layers: Apply multiple layers of release agent to the inner surface of the mold cavity, with each layer spaced 15-30 minutes apart. Then, lay the first layer of flow guide cloth on top of the release agent, lay the first layer of release cloth on top of the first layer of flow guide cloth, lay the first layer of reinforcing material on the first layer of release cloth, place the sandwich layer on the first layer of reinforcing material, lay the second layer of reinforcing material on top of the sandwich layer, lay the second layer of release cloth on top of the second layer of reinforcing material, lay the second layer of flow guide cloth on the second layer of release cloth, lay the vacuum bag on top of the second layer of flow guide cloth, and seal the edges of the vacuum bag to the mold with tape.

[0008] C. Injection: Install a vacuum tube on the vacuum bag, and install resin injection tubes on the first and second layers of the guide cloth. Connect the vacuum tube to a vacuum pump to create a vacuum. Use the vacuum negative pressure to inject the resin from the external resin tank into the first and second layers of the guide cloth. Then, inject the first and second layers of reinforcing materials. At the same time, use the guide cloth sleeve to connect the resin in the first and second layers of reinforcing materials.

[0009] D. Thermal Insulation Molding: The mold is heated and kept at a constant temperature, then cooled and demolded to obtain a composite sandwich structure.

[0010] In a preferred embodiment of the present invention, countersunk holes are respectively provided at both ends of the through hole, and the diameter of the countersunk holes is larger than the diameter of the through hole.

[0011] In a preferred embodiment of the present invention, the two ends of the flow guide cloth sleeve are respectively provided with flanges extending into the corresponding countersunk holes.

[0012] In a preferred embodiment of the present invention, an adhesive for fixing the corresponding flange is applied into the countersunk hole.

[0013] In a preferred embodiment of the present invention, the flow guide fabric sleeve and the flange adopt an integrated structure.

[0014] In a preferred embodiment of the present invention, the first layer of reinforcing material and the second layer of reinforcing material are respectively made of carbon fiber fabric or glass fiber cloth.

[0015] In a preferred embodiment of the present invention, in the heat preservation molding step, the mold is heated to 140~180°C and then kept at that temperature for 1~3 hours.

[0016] The beneficial effects of this invention are: the composite sandwich structure one-time injection molding process pointed out by this invention does not require pretreatment of the sandwich layer for resin injection. Multiple flow channels are formed by the flow guide sleeve to connect the resin on the upper and lower surfaces of the sandwich layer, reducing the problems of pores and other interface defects. It can also improve the integrity and stability of the structure after curing. It can be molded as a whole by one-time injection, with high production efficiency and reduced cost. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0018] Figure 1This is a schematic diagram of a preferred embodiment of a composite sandwich structure one-time injection molding process of the present invention;

[0019] Figure 2 yes Figure 1 A magnified view of part A in the middle. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Please see Figure 1 and Figure 2 The embodiments of the present invention include: Example

[0022] like Figure 1 The one-time injection molding process for the composite sandwich structure shown includes the following steps:

[0023] A. Processing of the sandwich layer: The sandwich layer is foamed to obtain a foamed sandwich panel with a planar or curved structure. Several through holes are processed or obtained by foaming on the foamed sandwich panel. Foamed plastic columns 5 are filled into the through holes. A flow guide cloth sleeve 13 is wrapped around the outer surface of the foamed plastic column 5 to obtain the sandwich layer 7.

[0024] In this embodiment, the through-hole array is distributed on the foamed sandwich panel, which has good uniformity; the foamed plastic column 5 uses the same material as the foamed sandwich panel to ensure heat insulation and sound absorption effects;

[0025] B. Laying out layers: Apply two layers of release agent 3 to the inner surface of mold 1, with a 20-minute interval between each layer to facilitate the drying and curing of each layer. Then, lay the first layer of flow-guiding cloth 4 on top of the release agent 3 to facilitate resin flow. Figure 2 As shown, a first layer of demolding cloth 11 is laid on top of the first layer of flow guide cloth 4 to facilitate subsequent demolding;

[0026] A first layer of reinforcing material 6 is laid on the first layer of release fabric 11, and the sandwich layer 7 is placed on the first layer of reinforcing material 6. A second layer of reinforcing material 12 is laid on top of the sandwich layer 7. In this embodiment, the first layer of reinforcing material 6 and the second layer of reinforcing material 12 are respectively made of glass fiber cloth to reinforce the structure of the sandwich layer 7.

[0027] A second layer of release cloth 8 is laid on top of the second layer of reinforcing material 12, a second layer of flow guiding cloth 9 is laid on top of the second layer of release cloth 8, and a vacuum bag 2 is laid on top of the second layer of flow guiding cloth 9. The edges of the vacuum bag 2 are sealed to the mold with tape to prevent air leakage.

[0028] C. Injection: Install a vacuum tube on vacuum bag 2, and install resin injection tubes on the first and second layers of guide cloth. Connect the vacuum tube to a vacuum pump to create a vacuum. Use the vacuum negative pressure to inject resin from the external resin tank into the first and second layers of guide cloth. Then, inject the first and second layers of reinforcing materials. At the same time, use the guide cloth sleeve to connect the resin in the first and second layers of reinforcing materials, reducing the problem of pore defects and improving the overall structure.

[0029] D. Thermal molding: The mold is heated and kept at 160°C for 3 hours, then cooled and demolded to obtain a composite sandwich structure. Example

[0030] like Figure 1 The one-time injection molding process for the composite sandwich structure shown includes the following steps:

[0031] A. Processing of the sandwich layer: The sandwich layer is foamed to obtain a foamed sandwich panel with a planar or curved structure. Several through holes are processed or obtained by foaming on the foamed sandwich panel. Foamed plastic columns 5 are filled into the through holes. A flow guide cloth sleeve 13 is wrapped around the outer surface of the foamed plastic column 5 to obtain the sandwich layer 7.

[0032] like Figure 2 As shown, countersunk holes are provided at both ends of the through hole, and the diameter of the countersunk holes is larger than the diameter of the through hole. In this embodiment, flanges 10 extending into the corresponding countersunk holes are provided at both ends of the flow guide sleeve 13. An adhesive for fixing the corresponding flanges 10 is applied to the countersunk holes, resulting in a stable structure.

[0033] In this embodiment, the flow guide sleeve and the flange adopt an integrated structure, which improves the stability of the flow guide sleeve in the through hole and avoids the problem of collapse during injection. It can improve the positional stability of the foamed plastic column 5 and guide the resin.

[0034] B. Laying out layers: Apply three layers of release agent 3 to the inner surface of mold 1, with a 15-minute interval between each layer to facilitate subsequent demolding. Then, lay the first layer of flow guide cloth 4 on top of the release agent 3, as shown below. Figure 2 As shown, a first layer of release fabric 11 is laid on top of the first layer of flow guide fabric 4, a first layer of reinforcing material 6 is laid on the first layer of release fabric 11, a sandwich layer 7 is placed on the first layer of reinforcing material 6, and a second layer of reinforcing material 12 is laid on top of the sandwich layer 7. In this embodiment, the first layer of reinforcing material 6 and the second layer of reinforcing material 12 are respectively made of carbon fiber fabric, and the structure is reinforced by carbon fiber fabric.

[0035] A second layer of release cloth 8 is laid on top of the second layer of reinforcing material 12 to facilitate subsequent demolding. A second layer of flow guiding cloth 9 is laid on top of the second layer of release cloth 8. A vacuum bag 2 is laid on top of the second layer of flow guiding cloth 9. The edges of the vacuum bag 2 are sealed to the mold with tape to avoid air leakage.

[0036] C. Injection: Install a vacuum tube on the vacuum bag 2, and install resin injection tubes on the first layer of guide cloth 4 and the second layer of guide cloth 9. Connect the vacuum tube to a vacuum pump to create a vacuum. Use the vacuum negative pressure to inject the resin from the external resin tank into the first layer of guide cloth 4 and the second layer of guide cloth 9. Then, inject the first layer of reinforcing material 6 and the second layer of reinforcing material 12. At the same time, use the guide cloth sleeve 13 to connect the resin in the first layer of reinforcing material 6 and the second layer of reinforcing material 12, improve the fluidity of the resin and the upper and lower connections after curing, reduce defects, and improve the connection stability of the resin on the sandwich layer 7.

[0037] D. Thermal molding: The mold is heated and kept at 170°C for 2 hours, then cooled and demolded to obtain a composite sandwich structure.

[0038] In summary, the composite sandwich structure one-time injection molding process proposed in this invention eliminates the need for pre-injection treatment of the sandwich layer, allowing for one-time injection molding of the composite sandwich structure, thus shortening the production cycle and reducing costs, while improving the quality and structural stability of the composite sandwich structure.

[0039] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A composite sandwich structure injection molding process in one shot, characterized in that, The method comprises the following steps: A. Processing of the sandwich layer: foaming molding of the sandwich layer to obtain a foamed sandwich plate with a flat or curved surface structure, processing or foaming molding a plurality of through holes on the foamed sandwich plate, filling the through holes with foamed plastic columns, wrapping the foamed plastic columns with a flow guide cloth sleeve to obtain the sandwich layer; B. Laying: applying a plurality of layers of release agent on the inner cavity surface of the mold, with an interval of 15-30 minutes between each layer, then laying the first layer of flow guide cloth on the release agent, laying the first layer of release cloth on the first layer of flow guide cloth, laying the first layer of reinforcing material on the first layer of release cloth, placing the sandwich layer on the first layer of reinforcing material, laying the second layer of reinforcing material on the sandwich layer, laying the second layer of release cloth on the second layer of reinforcing material, laying the second layer of flow guide cloth on the second layer of release cloth, laying the vacuum bag on the second layer of flow guide cloth, and connecting and sealing the vacuum bag edge to the mold by means of adhesive tape, wherein the two ends of the through hole are respectively provided with a counterbore, the diameter of the counterbore is greater than the diameter of the through hole, and the flow guide cloth sleeve is provided with a flange extending into the corresponding counterbore at both ends; C. Pouring: installing an air extraction pipe on the vacuum bag, installing resin pouring pipes on the first layer of flow guide cloth and the second layer of flow guide cloth, connecting the air extraction pipe to a vacuum pump for vacuum extraction, and using the vacuum negative pressure to pour the resin in the external resin tank into the first layer of flow guide cloth and the second layer of flow guide cloth, then pouring the first layer of reinforcing material and the second layer of reinforcing material, and simultaneously using the flow guide cloth sleeve to connect the resin in the first layer of reinforcing material and the second layer of reinforcing material; D. Heat preservation molding: heating and heat preservation of the mold, then cooling and demolding to obtain a composite sandwich structure.

2. The composite sandwich structure injection-compression molding process of claim 1, wherein, The counterbore is coated with an adhesive for fixing the corresponding flange.

3. The composite sandwich structure injection-compression molding process of claim 1, wherein, The flow guide cloth sleeve and the flange adopt an integrated structure.

4. The composite sandwich structure injection-compression molding process of claim 1, wherein, The first layer of reinforcing material and the second layer of reinforcing material respectively adopt carbon fiber fabric or glass fiber cloth.

5. The composite sandwich structure injection-compression molding process of claim 1, wherein, In the heat preservation molding step, the mold is heated to 140-180℃ and heat preserved for 1-3h.

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