JPH01316236A - Manufacture of compound molding - Google Patents

Abstract

PURPOSE:To improve the adhesive strength of a resin layer containing a reinforcing fibre body and a foam core, and obtain a high bending strength by boring a plurality of holes on a thermoelastic hard foam, and opening at least one end of each hole on the thermoelastic hard foam surface. CONSTITUTION:A thermoelastic hard foam core 1 is bored with plural number of holes 12 through inserting needles from the surface into the inner part. The foam core 1 is wrapped with a reinforcing fibre body 3 and placed within the cavity 5 of a mold 4, further, a liquid thermosetting resin 7 is injected, in a predetermined quantity, from the resin injection inlet 6 of the mold 4 into the cavity 5. Through heating the part of the mold 4 selectively in order, the heat is transmitted from the wall surface 8 of the mold 4 to the foam core 1 via the resin 7, so that the foam core 1 expands, and the reinforcing fibre body 3 is damped as well as pressed to the wall surface 8. While, through the resin pressure generated by the expansion of the foam core 1, the resin 7 comes also in the holes 2 of the foam core 1, thus, the resin in the holes and the resin damped the reinforcing fibre body 3 are cured and molded integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a molded article of a desired shape from a thermally expandable foam. This invention relates to an improvement in a method of integrally molding a thermosetting resin.

As one of the conventional technology composite molding methods, Maximilian Ware developed a new thermally expandable resin transfer molding method (the
rmal expansion resin tran
sfermolding process) has been proposed (Japanese Patent Application No. 61-303560). This method involves forming a thermoelastic rigid foam (foam core) into a predetermined shape, wrapping the preformed foam core with a reinforcing fiber, whose internal constraint surfaces form the shape of the final molded product, and selecting the preformed foam core. placing said wrapped tip-formed foam core in a mold capable of heating the area; injecting a liquid thermosetting resin to surround and wet the reinforcing assembly wrapped around the preformed foam core; By selectively heating certain areas of the mold to a sufficiently high temperature, the rigid 7 ohm core under the influence of the heated area of the mold expands, thereby reinforcing the foam core! Composite molding consisting of pressing the 1iM body surrounding surface against the internal constraint surface of the mold, terminating the heating of the rigid foam core to complete the molding process, and cooling the mold and removing the molded article from the mold. It is a method of molding articles and has several advantages over conventional composite molding methods. The main advantage of this method is that it allows moldings of complex shapes to be produced easily and inexpensively, and also for the production of new products that are unsuitable or impractical to make from wood, metal or many plastic materials. This method is usable.

Furthermore, this method is an economically attractive method for producing lightweight, high-strength, and high-rigidity sand inch core products by effectively utilizing lightweight materials. Thus, this method can be applied to a very wide range of manufacturing parts and elements of different designs and different shapes, for example structural parts of aircraft, motorized or non-motorized vehicles, Formula 1 stadiums, sports equipment, etc. This method itself is effective even when applied to

The present invention has been made to further improve the above-described thermally expandable resin transfer molding method and to further enhance the advantages of this method.

Problems to be Solved by the Invention As mentioned above, the thermally expandable resin transfer molding method is an extremely useful method from an economic point of view for manufacturing sand-inch core products that are lightweight, have high strength, and high rigidity. In order to fully exhibit such functions, it is necessary that the inner foam core layer and the thermosetting resin layer containing one reinforcing NIAM on the surface do not separate due to shearing force caused by external force. The present invention has been made in view of this point.

Means for Solving the Problems The present invention uses the thermally expandable resin transfer molding method described in J above, in which a large number of holes are bored in a thermoelastic rigid foam, and at least one end of the holes is formed on the surface of the thermoelastic rigid foam. It is characterized by an opening, thus greatly improving the adhesion between the resin layer containing reinforcing fibers and the foam core, and making it possible to obtain a molded product with high bending strength. .

The method of the present invention is a further improvement of the previously described thermally expandable resin transfer molding method (hereinafter sometimes abbreviated as TE RT-M method), but it Suitable polymers for forming the core are polyvinyl chloride, polyurethane, polyimide, etc., and polyimide is particularly suitable in fields where heat resistance is required.

Inside this polymer are various additives, such as pigments.

It may also contain inorganic fillers, reinforcing short fibers, etc.

On the other hand, as the reinforcing fiber body surrounding the foam core, for example, woven or knitted fabrics, nonwoven fabrics, or other fibrous structures are used.

I! For example, carbon fibers, para-aramid fibers, glass fibers, polyester fibers, etc. can be used.

In the TERTM method, a preformed foam core wrapped with reinforcing fibers is placed in a cavity in a mold, and a liquid thermosetting resin is injected around the preformed core to surround and moisten the reinforcing fibers. Epoxy resins are preferred as such resins. However, unsaturated polyester resins and polyurethane resins can also be used.

In the TERTM method, the mold is heated following injection of the thermosetting resin. Heat is transferred from the mold to the foam core through the thermosetting resin. When the core temperature reaches the expansion temperature of the core material, the foam core expands, forcing the wrapped surface of the core against the constraining surface of the mold.

The thermoset resin is injected into the mold long enough for the foam to expand enough to press against the mold interior surface and expel any excess resin from the mold via air handling provided within the mold. It must remain in liquid form for a period of time. Once the foam core is expanded, the thermoset resin must be molded and rapidly cured. Therefore, the curing properties of the thermosetting resin must be compatible with this stage of the molding process. The mold is then cooled and the resulting composite molded article is removed from the mold.

The temperature used in the molding process should correspond as closely as possible to the expansion temperature of the core material.

When the core material is polyimide, the temperature is generally about 149°C.
-205°C, polyvinyl chloride resins generally expand at temperatures of about 04°C to 163°C, polyurethane resins about 65°C to 107°C.
Since it expands at temperatures in the range of , these temperatures are preferably employed.

The manufacturing method of the present invention is intended to improve the thermoelastic foam (foam core) that plays the most important role in the above-mentioned TERTM method, and the materials and methods employed in the molding method of the present invention are is no different from the normal TERTM method.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 shows an example of one MR according to the present invention. A thermoelastic hard foam core 1 (hereinafter referred to as foam core) has a large number of holes 2 made by inserting needles into the core from the surface thereof. The foamed core 1 thus treated is wrapped with a reinforcing fiber body 3 and placed in the cavity 5 of the mold 4.

Thereafter, a predetermined amount of liquid thermosetting resin 7 is injected into the cavity 5 from the resin injection port 6 of the mold 4. By sequentially and selectively heating parts of the mold 4, heat is transferred from the wall surface 8 of the mold 4 to the foam core 1 via the resin 7, the foam core 1 expands, the reinforcing fiber body 3 is moistened, and the wall surface Pushed to 8. On the other hand, due to the pressure of the resin generated by the expansion of the foam core 1, the resin 7 also invades the holes 2 of the foam core 1.
The resin that has entered the hole 2 and the resin that has wetted the reinforcing fiber body 3 are integrally cured and molded.

The shape of the hole 2 is appropriately selected depending on the required function of the product, but - for boat fishing, it is cylindrical, and its dimensions are a needle (with a diameter of 0.75 to 1#1ffi and a length of 3 to 411III). It is preferable to use a foam core in which a needle is inserted into the foam core.

Another example of the arrangement of the holes 2 in the foam core 1 is shown in FIG. In Figure 2, holes 2 are drilled through the foam core 1, and the resin layers on both sides of the foam core 1 are connected, resulting in a molded product that is more rigid and highly adhesive. FIG. 2 (b+ is an example in which holes are drilled only on one side. In the present invention, holes may be bored in a part of the foam core 1, and may be used in combination with through holes as appropriate depending on the purpose. Of course.

Effects of the Invention The effects of the present invention are generally referred to as the anchor effect, and the adhesive force between the resin layer containing the reinforcing fiber body 3 and the foam core 1 is T.
The ERTM method makes it stronger, and the holes 2 are filled with resin sufficiently, so it is particularly strong against shearing forces and has high bending strength, so it is especially suitable for parts or parts of the product where sudden forces are expected. It is effective and particularly suitable for application in the production of aerospace-related parts.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams each explaining one embodiment of the present invention. 1... Thermoelastic rigid foam (foamed core) 2... Hole Patent applicant Teijin Ltd.

Claims (3)

[Claims] (1) Molding a thermoelastic rigid foam (foam core) into a predetermined shape, wrapping the preformed foam core with a reinforcing fiber, whose internal constraint surfaces form the shape of the final molded product, and forming the preformed foam core into a predetermined shape. placing said wrapped preformed foam core in a heatable mold over selected areas of the
The mold is molded by injecting a liquid thermosetting resin to surround and wet the reinforcing fibers wrapped around the preformed foam core, and by selectively heating predetermined areas of the mold to a sufficiently high temperature. Expanding the rigid foam core under the influence of the heating region, thereby pressing the reinforcing fiber surrounding surface of the foam core against the internal constraint surface of the mold, and terminating the heating of the rigid foam core to complete the molding process. In the method for producing a composite molded article, the method comprises: forming a plurality of holes in the thermoelastic rigid foam, and forming at least one end of the hole in the thermoelastic rigid foam. A method for producing a composite molded product characterized by having an opening on the hard foam surface. (2) The method for manufacturing a composite molded article according to claim (1), wherein the cross section of the hole is substantially circular. (3) The method for manufacturing a composite molded article according to claim (1) or (2), characterized in that the holes are formed by inserting a needle into the thermoelastic rigid foam.