JPH07232336A - Molding method for FRP molded products with built-in lightweight core material - Google Patents

Abstract

(57) [Summary] [Purpose] A molding method for FRP molded products with a built-in lightweight core material, in which the molding efficiency and product quality have been greatly improved compared to the prior art, and the working environment can also be significantly improved. I will provide a. [Structure] A lightweight core material made in advance from foamed plastic, wood, etc. is wrapped with a fibrous reinforcing material and then enclosed in a molding die to seal the mold and inject a plastic material into the molding cavity to form a lightweight core material. We adopted the method of molding integrally. The mold has a mold clamping vacuum circuit 14 provided around the mold mating surface so that the mold can be clamped by the atmospheric pressure. Moreover, a part of the mold wall is made of a flexible material so that the injection pressure of the plastic material is increased. It is preferable to use a material that is reversibly deformed by.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding an FRP molded product in which a light weight core material made of foamed plastic, wood or the like is built in the inner space of a hollow outer shell made of FRP.

[0002]

2. Description of the Related Art For example, as shown in FIG.
In order to make a ladder 50 for a yacht having a configuration in which the inner hollow portion of an outer shell 51 made of RP is filled with polyurethane foam 52 as a lightweight core material by a conventional manufacturing method, first, in FIG. As shown, using the molding die 60, the half-shells 51a and 51b divided into two in the thickness direction are molded by a hand lay-up method or a spray-up method. Next, as shown in FIG. 9C, the half shells 51a and 51b are joined together by an adhesive means or the like to form the outer shell 51. And
If the foamable polyurethane resin stock solution is filled from the inlet 53 provided in the outer shell body 51 and foamed and cured, the ladder 50 is formed.
Is completed. In another molding method disclosed in Japanese Patent Application Laid-Open No. 1-209126, the molding die of the foamed plastic core material is also used as the FRP molding die. The foam core material made using this mold with a two-part structure has an FRP layer of the required thickness formed on the outer periphery by hand lay-up or spray-up methods, and then stored in the original mold. When tightened, the foamed core material is compressed and reduced by the thickness of the FRP layer, and a hollow FRP molded product integrally incorporating the foamed core material is completed.

[0003]

However, the above-mentioned conventional manufacturing method has a number of problems as listed below. (1) The step of manually forming the FRP layer to be the outer shell by hand lay-up, spray-up method or the like has extremely low work efficiency and requires skill. (2) In addition, the worker is exposed to the vapor of volatile substances harmful to the body contained in the resin raw material, which is not preferable for hygiene. (3) The joining work of the divided outer shells is extremely inefficient and, according to an unskilled worker, the joining strength is insufficient and the product tends to be defective. (4) Needless to say, finishing work for unsightly joints is required. (5) Further, there is a possibility that the joint surface may be peeled off due to the foaming pressure of the foamable resin injected into the outer shell. (6) The reinforcing ribs are integrated with the outer shell by dividing the foamed core material into several parts and creating gaps between them, or by providing concave grooves or through holes in the foamed core material (see FIG. 6). When forming the resin material, it is difficult to spread the resin raw material through the gap or the through hole a, and the work efficiency is not significantly improved. Therefore, an object of the present invention is to sufficiently improve the molding work efficiency as compared with the prior art, to maintain a hygienic working environment, and to mold into an integral structure without dividing the outer shell, and to obtain the required strength. And a method for molding an FRP molded product that incorporates a lightweight core material so that even an unskilled person can surely manufacture a molded product having a good appearance.

[0004]

According to the present invention, there is provided a method for forming an FRP molded article containing a lightweight core material, which is made of foamed plastic, wood or the like, to produce a lightweight core material having a desired outer shape. FR wraps the material with fiber reinforcement
A method was adopted in which the molding die was housed in a P mold, the mold was sealed, and a plastic material was injected into the molding cavity to integrally mold the lightweight core material. The mold can be clamped at atmospheric pressure by surrounding the mold clamping vacuum circuit 14 on the mold matching surface, and a part of the mold wall is made of a flexible material. It is advisable to use a structure in which the wall is reversibly expanded and deformed by the injection pressure of the plastic material.

[0005]

According to the molding method of the present invention, a lightweight core material having a desired outer shape is made of foamed plastic, wood, or the like, and the lightweight core material is wrapped with a fibrous reinforcing material and used as a mold for FRP. A method is adopted in which the mold is enclosed and the mold is sealed, and a plastic material is injected into the molding cavity to be molded integrally with the lightweight core material. Therefore, it is extremely inefficient to manually impregnate the fibrous reinforcing material layer with the resin raw material by conventional hand layup or spray up, and it requires skill, and the work environment deteriorates due to the generation of harmful vapors. Since the work steps to be performed can be eliminated, the productivity is greatly improved. As a molding die, a vacuum circuit 14 for clamping is provided around the mating surface so that the mold can be clamped by the atmospheric pressure, and a part of the mold wall is made of a flexible material, and the mold is injected by the injection pressure of the plastic material. The wall reversibly bulges and deforms, and by using one that is configured with a low injection pressure to make it sufficient, a lightweight and inexpensive molding die will suffice, and the conventional mold clamping device becomes unnecessary.
Opening and closing operations of the mold are significantly simplified.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to the case of molding a FRP-made yacht ladder will be described with reference to FIGS.
This will be described with reference to FIG. As shown in FIGS. 1 and 2, the ladder A has a structure in which a lightweight core material 2 made of foamed plastic is built in an inner space of an outer shell body 1 made of FRP. It should be noted that a part of the lightweight core material 2 is replaced with a wood piece 3 which is stronger than the light weight core material 2, and the rudder is attached to the wood piece 3. The wood piece 3 is bonded or fitted to the lightweight core material 2 to be united.

Next, the overall configuration of the molding die B of the ladder A and the molding apparatus will be described with reference to FIGS. 3 and 7 and 8. The lower mold 11 of the molding mold B is an FRP having sufficient rigidity.
In this case, it is made by a conventional method using a polyester such as an isophthalic acid type, a bisphenol type or a vinyl ester type, and a chopped strand mat of glass fiber as a raw material.

As shown in the enlarged view of FIG. 8, the lower mold 11 has a wooden peripheral reinforcing member 13 embedded in the thickened portion of the peripheral portion. 12 is a molding cavity.
Reference numeral 14 denotes a mold clamping vacuum circuit that is provided around the upper surface (mold matching surface) of the peripheral portion of the lower mold 11, and has a shallow groove shape having a predetermined width. On the bottom surface of this groove, two long packing grooves 15a, 15a for attaching a long rod-shaped mold clamping packing 15 in the shape of a square rod are attached.
Are provided in parallel at a predetermined interval over the entire length of the groove.

The mold clamping packing 15 has its lower end fitted in the packing groove 15a, and its upper end side is the lower mold 1.
It is slightly projected from the mating surface of 1. Reference numeral 16 denotes a pressure reducing pipe which is assembled to the lower mold 11 so as to communicate with the mold clamping vacuum circuit 14 and is connected to a pressure reducing device (not shown).
Further, the lower mold 11 is provided with a plastic material injection port 17.

At least the flat part of the upper mold 18 of the mold B is made of a flexible material, and in this case, 20 to 30% of soft polyester is added to the chemically resistant polyester.
Made from blended flexible polyester resin and chopped strand mat. As shown in FIG. 8, the peripheral portion of the upper mold 18 is provided with the same reinforcing structure as that of the lower mold 11. Also, at the top, the molding cavity 12
An intake pipe 19 (see FIG. 3) for decompressing the inside is attached.

Next, the lightweight core material 2 of this embodiment shown in FIG. 4 is made of hard urethane foam, and is made by the casting method using the simple split mold 21 shown in FIG. The lower mold 21a of the split mold 21 is provided with a resin material injection port 22 and the upper mold 21b is provided with deaeration holes 23. In addition, in the split mold 21, a reinforcing wood piece 3 having a fitting groove is previously arranged and placed. When the lightweight core material 2 is made of expanded polystyrene, it is preferable that the lightweight core material 2 is covered with a solvent resistant film so as not to be corroded when the plastic material containing the styrene monomer is injected.

FIG. 7 is a schematic view of the entire structure of a molding apparatus for molding an FRP molded product by the so-called cast molding method using the molding die B described above. Reference numeral 31 in the drawing is a molding apparatus main body, which is not shown, but includes a raw material tank for storing plastic materials such as raw material resin and a curing agent, a quantitative feeding device for plastic materials, a decompression device, and a control unit for them, It can be moved by casters. Reference numeral 32 denotes a plastic material mixing head that mixes and discharges a raw material resin and a curing material at a predetermined ratio, and is connected to a raw material tank via a raw material hose 33 and a raw material pumping device.

Reference numeral 34 is a trap for accommodating an excessive amount of plastic material overflowing from the molding die B at the time of molding, and at the lid portion thereof, an end of an intake pipe 19 extending from the molding die B and a suction pipe 35 connected to a pressure reducing device. The start end is connected.
A valve 36 is interposed in the pressure reducing pipe 16.

Next, the operation of the above configuration will be described with reference to FIGS. First, the outer peripheral surface of the lightweight core material 2 previously made as described above is wrapped with a glass fiber mat (not shown) so as to have a bulk corresponding to the internal volume of the molding cavity 12. Then, the lightweight core material 2 is attached to the upper die 1 of the forming die B.
8 is removed and put in the lower mold 11.

After that, when the upper mold 18 is placed on the lower mold 11 to operate the pressure reducing device and the valve 36 is opened, the pressure in the mold clamping vacuum circuit 14 is reduced. Even without performing a troublesome mold clamping operation using a fastener, the upper mold 18 is naturally brought into close contact with the lower mold 11 by the atmospheric pressure, and the mold clamping operation is completed extremely easily and quickly.

Therefore, the injection nozzle of the mixing head 32 is connected to the injection port 17 to fill the molding cavity 12 with a predetermined amount of liquid plastic material. At this time, the intake pipe 19 is communicated with the atmosphere. However, when the material viscosity is extremely high, a slight negative pressure is applied to assist injection. This filling pressure is about 0.93 Kg / cm ² at the injection port 17 part.
Inside and outside (about 0.9 atm) and 3-6 Kg / cm ^{2 of the} conventional technique.
It is set much lower than.

The flow of the injected plastic material is hindered by the glass fiber layer disposed in the molding cavity 12, and as shown by the phantom line in FIG. Since the portion is pushed up to expand the volume of the molding cavity 12, an extremely low injection pressure is sufficient as described above. At the stage where the filling of the plastic material is completed, a resin-unfilled void remains in the peripheral portion of the molding cavity 12.

Therefore, if the inlet 17 is sealed with a plug (not shown) and the intake pipe 19 is connected to a pressure reducing device,
Since the air in the unfilled void is sucked and removed, the plastic material in the molding cavity 12 follows the fiber gaps of the glass fiber layer and spreads throughout the molding cavity 12, and the bulging and deforming upper mold 18 deforms. It returns to its original shape due to the restoring force.

The plastic material, which is somewhat overfilled in advance, is then sucked and stored in the trap 34. After that, when the plastic material is allowed to cure in the depressurized state, the plastic material exhibits a strong adhesive force to the lightweight core material 2 in the progress stage of this curing, so that the FRP outer shell body 1 and the lightweight core material are provided. 2 and are firmly joined together. Therefore, if the upper mold 18 is removed by releasing the reduced pressure, it is possible to take out a very good completed ladder A in which no or almost no bubbles remain in the outer shell 1 portion.

According to the above-mentioned molding method, since the injection pressure of the plastic material is not more than atmospheric pressure, the molding die B can have a simple structure, and the die manufacturing cost can be greatly reduced and the die weight can be reduced as compared with the prior art. Is achieved. And the mold clamping is the vacuum circuit 1 for mold clamping.
Since the inside of the mold 4 is depressurized by using the atmospheric pressure, the conventional mold clamping tool becomes unnecessary, and the opening and closing operation of the valve of the pipe connecting the mold clamping vacuum circuit 14 and the pressure reducing device is sufficient. The tightening and releasing operation can be performed extremely efficiently.

FIG. 6 shows a second embodiment of the present invention. The difference from the first embodiment is that the light-weight core material 2 is divided into three and an appropriate gap a for rib formation is provided between the divided portions, or the light-weight core material 2 is provided at an appropriate interval. Through holes a are provided, and glass fibers are also provided in these gaps (through holes) a.

The lightweight core material 2 is wrapped with glass fibers in the same manner as in the above-mentioned embodiment, and the gap a is filled with the glass fibers and then housed in the molding cavity 12. Then, if the plastic material is injected into the molding cavity 12, it will naturally penetrate into the gap (through hole) a, so that it is difficult to completely fill the plastic material into this portion as in the case of the conventional hand layup. In addition, there is almost no risk of defective products due to incomplete filling.

In each of the above-mentioned embodiments, the object of the present invention can be achieved even if the detailed structure is appropriately changed. For example, the lightweight core material 2 may be made of an inorganic material such as foamed concrete, or the lightweight core material 2 may have a metal insert incorporated therein or attached thereto. If the molded product has a relatively large wall thickness, it is not necessary to form a part of the mold wall with a flexible material. The molding method is not limited to FRP,
It is also suitable for molding various plastics that have poor fluidity when melted. Further, the reinforcing fiber is not limited to glass fiber, of course.

[0024]

As is apparent from the above description, according to the method for molding an FRP molded product containing the lightweight core material according to the present invention, the conventional technique was dependent on the hand layup method and the spray up method. Compared to, various excellent effects as listed below can be obtained. (A) Since the FRP layer, which is the outer shell of the product, is formed by the method of injecting the plastic material into the closed mold, the molding work efficiency can be remarkably increased. (B) Further, the worker does not have to be exposed to the vapor of volatile substances contained in the plastic material and harmful to the body. (C) Since the outer shell is not attached and finished, an unskilled person can surely form a molded product having a required strength and a good appearance. (D) In order to integrally form the reinforcing ribs on the outer shell, even if the lightweight core material is divided into several parts to form a gap or to form a groove or a through hole, the injection pressure of the plastic material and the Forcibly exhausting the inside of the mold allows the plastic material to easily and surely reach these gaps, grooves, through holes and the like. (E) Therefore, even when the reinforcing ribs are integrally provided on the outer shell, the work efficiency is further improved as compared with the conventional manual molding method such as hand lay-up. (F) Since the lightweight core material does not require special dimensional accuracy,
Even plastic molded products can be made relatively inexpensively.

[Brief description of drawings]

FIG. 1 shows a first embodiment in which the present invention is applied to a case of forming a ladder for a yacht, and is a vertical sectional side view of the ladder.

FIG. 2 is a vertical sectional front view of the same.

FIG. 3 is a transverse cross-sectional view of a forming die, which also serves as a description of a method for forming a ladder.

FIG. 4 is a transverse sectional view of the same lightweight core material.

FIG. 5 is a transverse cross-sectional view of a mold for lightweight core material of the same.

FIG. 6 is a view, corresponding to FIG. 3, showing a second embodiment of the present invention.

FIG. 7 is a sketch showing the overall structure of the molding apparatus.

FIG. 8 is an enlarged vertical sectional view of a main part, showing a mold clamping structure of a molding die.

FIG. 9 illustrates a conventional technique and is an explanatory diagram of a molding process.

[Explanation of symbols]

 A Molded product (ladder) B Mold 1 Outer shell 2 Light weight core material 3 Wood piece a Gap (through hole) 11 Upper mold 12 Mold cavity 12a Edge portion 13 Perimeter reinforcement 14 Mold clamping vacuum circuit 15 Mold clamping packing 15a Packing Groove 16 Decompression pipe 17 Injection port 18 Upper mold 19 Intake pipe 21a Lower mold 21b Upper mold 22 Injection port 23 Degassing hole 31 Molding device main body 32 Mixing head 33 Raw material hose 34 Trap 35 Suction pipe 36 Valve 50 Ladder 51 Outer shell 52 Light weight core material 53

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29K 105: 20 711: 14

Claims (2)

[Claims] 1. A material such as foamed plastic or wood,
Create a lightweight core material with the required outer shape, wrap the lightweight core material in a fiber reinforcement, store it in a FRP mold, seal the mold, and inject a plastic material into the mold cavity. A method for molding an FRP molded product having a built-in lightweight core material, characterized in that it is integrally molded with the lightweight core material. 2. The molding die can be clamped at atmospheric pressure by arranging a mold clamping vacuum circuit 14 on the mold mating surface, and a part of the mold wall is made of a flexible material. 2. The method for molding an FRP molded article containing a lightweight core material according to claim 1, wherein the mold wall is configured so as to reversibly bulge and deform by the injection pressure of the plastic material.