Industrial composite manufacturing method

Abstract

The present invention proposes a method of industrial composite manufacturing. The method combines the resin transferring molding method with vacuum process and compression process in appropriate orders for achieving high quality products. In the curing process, microwaves are used to harden the plastic resin in the mold. Specifically, the main steps of the method are following: step 1: preparation of materials and equipment; Step 2: Disposition of the reinforced fibers/fabrics and mold closing at the extend position; Step 3: Vacuum and transfer plastic resin into the mold; Step 4: Mold closing by compression pressure; Step 5: Plastic resin curing by using a microwave system; Step 6: Open the mold and take the composite product.

Claims

1. An industrial composite manufacturing method comprising the following steps: Step 1: Preparation of materials and equipment; said preparation comprising preparing necessary materials and equipments including: a mold set comprising upper and lower molds, reinforced fibers/fabrics, plastic resin, additives, vacuum pump, compression machine, microwave system and other tools; Step 2: Disposition of the reinforced fibers/fabrics and mold closing at an extended position; the reinforced fibers/fabrics are arranged in the mold, then an upper mold is set at an extended position to make space (at least 30%) for the plastic resin by using wedges with air-insulation ability; Step 3: Vacuum and transfer plastic resin into the mold; comprising, after vacuuming air inside the mold, the plastic resin is transferred into the mold; Step 4: Mold closing by compression pressure; comprising, disassembling the wedges and then the upper mold is closed at a designed position by using a compression pressure; Step 5: After the mold closing by compression pressure step, plastic resin curing by using a microwave system; the plastic resin is cured by using microwave system; and Step 6: Open the mold and take the composite product; after curing process, the mold is firstly cooled, then is opened to take out the composite product.

2. The industrial composite manufacturing method according to the claim 1, wherein in the Step 2, the upper mold is firstly closed at the extended position where the distance between the upper mold and the lower mold is set greater than a thickness of the composite product by at least 30%.

3. The industrial composite manufacturing method according to claim 1, wherein in the Step 4, the compression pressure is applied to the mold set in order to push an excess plastic resin out and move the upper mold to a position corresponding to a designed thickness of the composite product; the compression pressure process takes place immediately after the plastic resin fills the mold; the value of the compression pressure is taken from 0.2-20 Mpa.

4. The industrial composite manufacturing method according to claim 1, wherein in the Step 5, thermosetting resin in the mold is hardened by a microwave with frequency from 1-15 GHz and wavelength from 1-50 cm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Block diagram of the industrial composite manufacturing method

(2) FIG. 2: Figure illustrating the second step of the method.

(3) FIG. 3: Figure illustrating the third step of the method.

(4) FIG. 4: Figure illustrating the fourth step of the method.

(5) FIG. 5: Figure illustrating the fifth step of the method.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

(6) The quality of composite materials is evaluated through many factors. One important factor is the consistency, low pore ratio in the composite structure improves the material strength, durability and resistance to dynamic loads. The curing degree of the plastic resin matrix also affects considerably to the composite product quality. A uniform curing of the resin matrix of composite materials allows a continuous force transmission in the composite structure. Another important factor is the geometric quality of the composite products. In the high-tech application, many composite products are required to have smooth surfaces as well as a precise thickness.

(7) In order to satisfy all the quality requirements, the industrial composite manufacturing method proposed in this invention includes the following steps:

(8) Step 1: Preparation of materials and equipment

(9) Step 2: Disposition of the reinforced fibers/fabrics and mold closing at the extend position

(10) Step 3: Vacuum and transfer plastic resin into the mold;

(11) Step 4: Mold closing by compression pressure;

(12) Step 5: Plastic resin curing by using a microwave system;

(13) Step 6: Open the mold and take the composite product.

(14) Specifically, the steps of the method are described as follows:

(15) Step 1: Preparation of materials and equipment. Referring to FIGS. 1 and 2, necessary equipment and materials are prepared as follows: Raw materials include plastic resin, reinforcing fibers/fabrics and additives; Mold must made by non-conductive materials that is low affected by electromagnetic waves such as wood, concrete, porcelain, plastic . . . . Specifically, the mold is composed by: the interior surface (1) is designed as the shape of the product; the wedges (2) have the air insulation ability, help to keep the distance between bottom mold and upper mold and can be disassembled; bottom mold (3); upper mold (4); inlet valve (5); and outlet valve (6). Main machines include vacuum pump, compressing machine and microwave system; Other equipment: balance, resin tank, pipelines, valves, pressure gauges . . . .

(16) Step 2: Disposition of the reinforced fibers/fabrics and mold closing at the extend position. Referring to the FIGS. 1 and 2, reinforcing fibers/fabrics (1) are arranged in the molds corresponding to the design. The fiber volume content and the fiber orientation are determined based on the design principles and the design standards to satisfy the load-bearing conditions of the product. After fibers/fabrics arrangement on the surface of the bottom mold, place the upper mold (4) at the extend position where the distance between the upper mold (4) and the bottom mold (3) is greater than the thickness of the product by at least 30%. The distance is held by the wedges (2) that have the air insulation ability. This extension creates more space for resin flow transferring into the mold.

(17) Step 3: Vacuum and transfer plastic resin into the mold. Referring to the FIG. 1 and FIG. 3, after the disposition of fibers/fabrics into the mold, the vacuum in the mold is carried out. Firstly, the inlet valve is closed (5); then the outlet valve (6) which connects the molds and the vacuum pump is opened; Start the vacuum pump machine in order to eliminate air in the mold. By using a pressure gauge measuring the pressure in the mold, it can be determined the moment when the mold interior reaches the vacuum state. After reaching the vacuum state, close the outlet valve (6), then turn off the vacuum machine. Then, the inlet valve (5) connected between the resin tank and the mold is opened to transfer the plastic resin into the mold until the plastic matrix resin fills the mold.

(18) Step 4: Mold closing by compression pressure. Referring to the FIG. 1 and FIG. 4, after the plastic resin filled the mold, the wedges (2) are disassembled. Then, compression pressure is applied on the upper mold in order to push the excess plastic resin out and move the upper mold to the designed position corresponding to the designed thickness of the composite product. The pressing pressure on the upper mold is chosen from 0.2 MPa to 20 Mpa depending on the type of plastic resin and the shape of the product. It can be seen that the applied pressure in the method is 2-200 times greater than the pressure in the conventional VARTM method.

(19) Step 5: Plastic resin curing by using a microwave system. Referring to FIG. 1 and FIG. 5, after the upper mold is closed at the product thickness position, the thermosetting resin in the mold is then cured by microwave, where the microwave frequency could be chosen from 1-15 GHz, and the wavelength can be from 1 to 50 cm. By using the curing microwave system, the entire product can be cured at the same time. The curing time depends on the size, thickness and type of used plastic resin.

(20) Step 6: Open the mold and take the composite product. After the curing process, keep the mold during at least 30 minutes for cooling, then open the mold to get the product.

(21) In the method, the two surface sides of the product are in contact with two solid surfaces of the mold. Therefore, two surfaces of the products are smooth, and the thickness of the product can be accurately controlled according to the designed thickness. The consistency of the composite products is also high due to the effects of two processes: the vacuum process in the mold and the compressing process with pressure 2-200 times higher than conventional compression pressure in the VARTM method. Finally, the curing process could be faster and more energy saving, because by using microwaves, energy could be quickly transmitted for curing the plastic resin matrix. The method of the present invention could be automated at high level with medium investing cost. Especially, with time saving in the curing process, the method could improve the productivity of the manufacturing unit.