JPH08290479A - Molding method for composite material - Google Patents

Abstract

PURPOSE: To mold at a comparatively low temperature and in a short time by preforming a molding intermediate at a specified temperature or under, and then combining a vacuum air pressed forming process and pressure and heat molding. CONSTITUTION: A molding intermediate composed of a reinforcing fiber and a thermosetting resin is cut into a pattern required for molding a molded product, laminated, and preformed under the heat of 60 deg.C or under. A preformed product 16 thus provided is set in a molding tool 15 for which the setting temperature is adjustable. Then the mold 15 which can be heated is disposed on the lower face, and a stretchable film 8 is fitted on the upper section of the preformed molding intermediate 16 by a vacuum pressure molding machine with a heat pressurized gas casing upper face plate 4 having its lower section formed by the stretchable rubber film 8, and pressure is reduced by a vacuum pump 18 to deaerate a preformed product. Then, pressurized hot air is flowed into the stretchable film casing and pressurized and heated to manufacture a molded product. A product with only a small number of pinholes and voids can be molded in a short time by the arrangement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved molding method for composite materials, especially advanced composite materials (ACM).

[0002]

2. Description of the Related Art For molded articles of so-called advanced composite materials (ACM), reinforcing fibers such as carbon fibers and glass fibers and a molding intermediate material made of thermosetting resin are laminated and added to an autoclave, a vacuum bag, a press or the like. Various molded products are obtained by the pressure molding method. With the autoclave molding method, a complicated curved surface molded product can be obtained with high quality, but the molding preparation process is complicated, the molding time is long, and it is not suitable for mass production. On the other hand, the vacuum bag molding method is less restricted in equipment, but basically requires the same process as the autoclave molding, and is slightly inferior to the autoclave method in terms of material defects such as pinholes and voids. In addition, the press molding method can be cycled up with few pinholes and the like, but the shape and size are limited, the die cost becomes enormous, and cost problems often occur.

[0003]

[Problems to be Solved by the Invention] It is an essential element for the development of this industry to improve productivity and create a system capable of mass production without deteriorating the performance of high performance advanced composite materials (ACM). However, the conventional molding technique has advantages and disadvantages as described above, and in reality, there is no satisfactory molding method. The present invention provides a molding method of a composite material, which is suitable for ACM molding for general industrial use and can be molded at a relatively low temperature in a short time.

[0004]

That is, the gist of the present invention is as follows.
A molding intermediate material consisting of reinforced fiber and thermosetting resin is laminated, preformed at a temperature of 60 ° C or less, set in a mold capable of adjusting heating temperature, and a decompression bag is formed on the side of the molded product through an elastic film. And a step of pressurizing with heated gas through the stretchable film, followed by press-heating and curing with a mold and heated gas.

The molding intermediate material used in the present invention is 70 to 130 ° C. for so-called high strength and high elastic modulus fibers such as carbon fiber, aramid fiber, glass fiber and alumina fiber.
Molding intermediate materials impregnated with a thermosetting resin selected from epoxy resins, unsaturated polyester resins, vinyl ester resins, and phenolic resins, which can be cured at relatively low temperatures, include woven fabrics and unidirectionally aligned materials. Examples of the material include materials used for ordinary pressure molding such as sheets and various oriented sheets of short fibers, roving prepreg, and sheet molding compounds. A prepreg is an uncured tack obtained by impregnating these woven fabrics, unidirectionally aligned sheets, rovings, etc., with a thermosetting resin such as epoxy, vinyl ester, or phenol by a solution impregnation method or a film impregnation method. It refers to the resin-impregnated intermediate material that it has. Such a prepreg is a molding intermediate material that is laminated along a mold and is heated under pressure to form a molded product that matches the shape of the mold.

In the present invention, these molding intermediate materials are employed in combination with various measures for increasing the molding cycle. First, a molding intermediate material is cut into a pattern necessary for shaping a molded product, laminated, and preformed (preform) under heating at 60 ° C. or less. The preform thus obtained is set in a mold whose heating temperature can be adjusted.

Next, as the method of pressure heating and molding, in the present invention, a molding method using a vacuum pressure air molding machine having expansion and contraction variability is adopted. That is, a heatable mold is arranged on the lower surface, and a vacuum pressure air molding machine (FIG. 1) having a heating and pressurizing gas box upper surface plate that forms a lower portion with a stretchable rubber-based film is used to form a preformed intermediate material. A stretched film is fitted on the upper part, the pressure is reduced, the preform is degassed, and then pressurized heated air is flown into the stretchable film box to be heated under pressure to obtain a molded product.

According to this method, unlike the autoclave molding and the vacuum bag molding, the labor for forming the vacuum bag is unnecessary, and since the pressurizing process is combined, the product having less pinholes and voids than the vacuum bag molding. Is obtained. Further, by appropriately selecting the setting of the heating temperature, it is possible to perform molding at a relatively low temperature and low pressure in a short time, which is extremely useful as a mass production molding and a low cost molding method. If necessary, a gel coat having good adhesiveness may be applied at the stage of preforming of the present invention to form a pinhole-free molded product having a problem in the surface layer.

[0009]

EXAMPLES The present invention will be described more specifically by way of examples. (Example 1) Elastic modulus of 24 tons / m manufactured by Mitsubishi Rayon Co., Ltd.
A carbon fiber cloth having m ² and 3000 filaments was prepared and impregnated with a 80 ° C. curable epoxy resin to prepare a molding intermediate material (A). Then, the pattern-cut molding intermediate material (A) is laminated using a bicycle wheel preforming mold, and the temperature is 50 ° C. by a vacuum drape molding method.
It was preformed by pressurizing at 1 atm to obtain two shells of foil. The preformed front and back shells are set in a mold 15 which can be heated by using the vacuum pressure air forming machine shown in FIG. 1, and the space covered with the elastic silicone rubber film 8 is depressurized to remove the preformed product. 3 kg / mm ² , 120 ° C. by heating and starting heating of the heater, and introducing heated pressurized gas into the upper surface compressed air box through the air heater 19.
And heat-molded under pressure for 15 minutes. The foil shell thus obtained had almost no pinholes on its surface, and a carbon fiber reinforced resin bicycle wheel having a clean surface could be obtained by the subsequent joining step and clear coating. The molding cycle time at this time was 30 minutes.

For comparison, when a similar molded product was manufactured by the conventional autoclave molding method, a molding cycle of 6 hours was required. Also, the loss of molding auxiliary materials was large.

[0011]

According to the present invention, by performing preforming of a molding intermediate material at a relatively low temperature and then combining with a vacuum pressure air molding method, press-heating molding can be performed, thereby achieving high performance at a relatively low temperature in a short time. Can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an apparatus used for carrying out the present invention.

[Explanation of symbols]

 1 Basework 2 Heater 3 Vacuum Line 4 Presswork 5 Compressor 6 Compressed Air Storage Tank 7 Compressed Air Valve 8 Stretchable Film 9 Seal 10 Heater 11 Blower Fan 12 Pressure Reduction Valve 13 Frame 14 Hydraulic Cylinder 15 Mold 16 Prepreg 17 Bleed Cross 18 Vacuum Pump 19 Air heater

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Claims (1)

[Claims] 1. A molding intermediate material comprising a reinforcing fiber and a thermosetting resin is laminated, preformed at a temperature of 60 ° C. or lower, set in a mold capable of controlling heating temperature, and molded via a stretchable film. A method for molding a composite material, comprising: degassing the object side with a decompression bag; and pressurizing with heated gas through a stretchable film, followed by pressurizing and heating and curing with a mold and heated gas.