JPH0649300B2 - Molding method of fiber reinforced plastic and its molding die - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is directed to a synthetic resin in which no resin unfilled portion is generated even when the raw material resin is filled at a low injection pressure. In particular, it relates to a method for molding fiber-reinforced plastic and a molding die used in this molding method.

(Prior Art) A so-called fiber-reinforced plastic in which a fibrous reinforcing material made of glass fiber, carbon fiber or aramid fiber is embedded is much lighter than metals such as iron, does not corrode, and is comparable to iron. Strength is obtained, and since it is excellent in moldability,
Widely used in various industrial fields.

As a method for molding this fiber-reinforced plastic, for example, a liquid raw material resin obtained by mixing an unsaturated polyester resin with a curing agent thereof is used.First, the raw material resin is brushed or sprayed on the surface of a molding die to form a gel coat layer. The so-called hand lay-up method or spray-up method, in which the glass fiber web is placed on top of this and the raw material resin layer is further applied onto the glass fiber web to impregnate the raw material resin into it, is commonly used. It is being appreciated.

In addition, an SMC molding method is also used in which a sheet mold compound, in which a raw material resin that is cured by heating is impregnated in a glass fiber web, is sandwiched between split molds and heated and pressed.

Furthermore, a casting method is also used in which a raw material resin is pressed into a molding cavity using a dedicated injection machine.

(Problems to be Solved by the Invention) However, since the above hand layup method and spray up method use an open type, harmful gases such as styrene monomer in the raw material resin, which are harmful to the human body, evaporate and deteriorate the working environment. Moreover, the work efficiency was low.

In addition, while the SMC molding method can improve the molding work efficiency, a considerable portion around the sheet becomes a non-reusable burr depending on the shape of the molded product, and a heating device for curing the resin. There was a difficulty that required.

On the other hand, the method of injecting the raw material resin into the molding cavity is
Since a closed mold is used, a good working environment can be maintained, but on the other hand, a sturdy mold that can withstand the injection pressure of the resin and a mold clamping means corresponding thereto are required.

According to this method, since the fibrous reinforcing material impedes the flow of the raw material resin, it is difficult to spread the resin to the end of the molding cavity.For products with thin wall thickness, the molding cavity Even if the method of decompressing the inside is adopted, a defective molded product in which voids are left in the peripheral portion is likely to occur.

Therefore, an object of the present invention is to use a molding die having a simple structure as much as possible in a method of using a closed mold, and even a product having a thin wall thickness can surely pass the resin to every corner of the mold. The present invention provides a method for molding a fiber-reinforced plastic and a mold for the same.

[Constitution of the Invention] In order to achieve the above-mentioned object, the molding method of the fiber reinforced plastic according to the present invention comprises the following molding steps a) to c), a) a mold at least on a flat surface. A step of filling a predetermined amount of raw material resin into a molding cavity 2 formed by an upper mold 9 having walls made of a flexible material and a lower mold 1 having rigidity.

b) A step of closing the injection port 11 of the raw material resin.

c) In the step b), a step of degassing the unfilled void a in the molding cavity 2 caused by the mold wall bulging due to the injection pressure of the raw material resin.

It is configured to include.

A fibrous reinforcing material may be embedded in the raw material resin.

The mold according to the present invention comprises a lower mold 1 having a rigid structure and an upper mold 9 having a mold wall made of a flexible material at least in a flat molding surface. After the filling, the deaeration port 10 for eliminating the air in the unfilled void a of the raw material resin in the molding cavity 2 is provided.

The upper mold 9 and / or the lower mold 1 includes a plurality of split molds 2.
It is preferable that the pressure reducing seals are formed on all of the mold matching surfaces.

When the depressurizing seal part is provided with a plurality of mold clamping packings 5 in parallel with each other on the mold matching surface, and a mold clamping vacuum circuit 4 formed between these mold clamping packings 5 and 5 is filled therein. good.

(Operation) A predetermined amount of raw material is placed in a molding cavity 2 formed by a lower mold 1 having rigidity and an upper mold 9 having a molding surface made of a flexible material in a flat molding surface. When the resin is filled, the flexible mold wall portion swells due to the injection pressure of the raw material, so that the raw material resin can be filled with the low injection pressure even in the molding cavity 2 having a large flow resistance to the injected resin.

Then, when the unfilled void a of the resin generated in the molding cavity 2 due to the bulging of the die wall is degassed, the bulged die wall returns to its original mold, and the unfilled void a also remains. The resin travels back and forth to obtain a molded product of the desired shape, completely void free.

Further, by depressurizing the depressurizing seal portion 4 provided on all the die mating surfaces of the large-sized forming die composed of the plurality of split dies 21, 22, 23, the conventional die clamping tool is not required. The mold clamping is performed all at once, and the large-capacity molding cavity 2 can be easily formed without using the conventional mold clamping tool.

Then, the decompression seal portion 4 is communicated with the atmospheric pressure, whereby the mold clamping is released all at once.

(Example) An example in which the present invention is applied to the molding of a glass fiber reinforced plastic product in the form of a thin panel will be described below.
A description will be given with reference to FIGS.

First, in FIGS. 1 to 6 showing the constitution of the mold A, 1 is a lower mold made of reinforced plastic having sufficient rigidity, and in this case, isophthalic acid type, bisphenol type or vinyl ester type. It is manufactured by a conventional method using a polyester such as a system and a chopped strand mat of glass fiber.

A molding cavity 2 having a uniform depth is formed on the upper surface of the plate-shaped lower mold 1. An edge portion 2a which is gradually shallower like a knife edge is provided on the peripheral portion of the forming cavity 2. Then, as shown in FIG. 6, a wooden peripheral reinforcing material 3 is embedded in the peripheral portion of the lower mold 1.

Reference numeral 4 denotes a mold clamping vacuum circuit, which is provided around the upper surface of the peripheral portion of the lower mold 1 and serves as a decompression seal portion, and has a shallow groove shape having a predetermined width.
On the bottom surface of this groove, two packing grooves 4a to which a long mold clamping packing 5 having a square cross section can be attached are provided in parallel at predetermined intervals.

The mold clamping packing 5 has its lower end fitted in the packing groove 4a, and its upper end side slightly protrudes from the upper surface of the lower mold 1. Reference numeral 6 denotes a mold clamping pipe joint that communicates with the mold clamping vacuum circuit 4 and is connected to a pressure reducing device (not shown).

Reference numeral 7 denotes a vacuum forming circuit provided around the upper surface of the lower mold 1, which is located inside the mold clamping pipe joint 6 and communicates with the forming cavity 2 through a pinch-off 8. In this case, pinch off 8
Has a height of 0.1 to 0.5 mm and a length of 10 to 60 mm.

9 is an upper mold made of a flexible material. In this case, it is made of a flexible polyester resin in which 20 to 30% of a polyester for softness is mixed with a chemically resistant polyester and a chopped strand mat. Has been.

As shown in FIG. 6, a reinforcing structure is provided on the peripheral portion of the upper mold 9 having a thin disk shape, as in the peripheral structure of the lower mold 1.

Reference numeral 10 denotes a suction pipe joint, which is provided in a penetrating manner on the above-mentioned reinforcing peripheral edge portion so as to communicate with the inside of the forming vacuum circuit 7.

Reference numeral 11 denotes an injection port for the raw material resin, which is provided in the center of the upper mold 9 and from which the raw material resin is filled into the molding cavity 2.

Next, a seventh outline of the overall configuration of the molding system for molding the fiber-reinforced plastic using the above-mentioned molding die A is shown.
In the figure, reference numeral 12 is a molding apparatus main body, which accommodates a raw material tank for raw material resins and curing agents, a quantitative feed apparatus for raw material, a decompression apparatus and its control unit, and can be moved by casters.

Reference numeral 13 denotes a raw material resin mixing head which mixes and discharges a raw material resin and a curing agent thereof at a predetermined ratio, and is connected to a raw material tank via a raw material hose 14 and a raw material pumping device.

Reference numeral 15 is a trap for containing the raw material resin overflowing from the molding die A at the time of molding, and is provided with a suction side pipe joint 15a and a suction side pipe joint 15b at its lid portion. The suction side pipe joint 15b is connected to the pressure reducing device through the intake pipe 16, and the suction side pipe joint 15b
The a is connected to the suction pipe joint 10 of the upper mold 9 via the suction pipe 17.

Further, the mold clamping pipe joint 6 provided in the lower mold 1 is provided with the intake pipe 18
It is connected to the decompression device via. A valve 19 is interposed in the intake pipe 18.

Next, referring to FIGS. 1 to 5, the operation of the above configuration will be described.

First, the glass fiber C for strengthening the molded product D is placed in the molding cavity 2 of the lower mold 1 from which the upper mold 9 has been removed, with the required arrangement (FIG. 1).

Then, the decompression device is driven, the upper mold 9 is placed on the lower mold 1, and the valve 19 interposed in the intake pipe 18 is opened.
Since the inside of the mold clamping vacuum circuit 4 is decompressed, the upper mold 9 is naturally brought into close contact with the lower mold 1 to perform mold clamping without using mold clamping tools as in the conventional case (FIG. 2).

Therefore, the injection nozzle of the mixing head 13 is set to the injection port 1
1, and a predetermined amount of liquid synthetic resin raw material is filled in the molding cavity 2. At this time, the forming vacuum circuit 7 is communicated with the atmosphere. However, if the resin viscosity is extremely high,
Apply a slight negative pressure to assist injection.

This filling pressure is about 0.9 atm (about 0.93 k
g / cm ² ) Set inside and outside, much lower than the conventional 3-6 kg / cm ² .

The injected raw material resin is impeded by the flow of the glass fibers C arranged in the molding cavity 2 and pushes up the flexible upper mold 9, so that the raw material resin is injected with an extremely low injection pressure as described above. Can be injected. When the filling of the raw material resin is completed, the resin-unfilled void a remains in the peripheral portion of the molding cavity 2 (FIG. 3).

Therefore, when the injection port 11 is sealed with a plug (not shown) and the molding vacuum circuit 7 is connected to a decompression device, the air in the unfilled void a is sucked and removed through the pinch-off 8 portion, so that the molding cavity 2 The raw material resin therein goes all the way into the molding cavity 2 through each fiber gap of the glass fiber C, and the upper mold 9 bulged and deformed as shown in FIG.
It returns to the normal position in FIG. 2 (FIG. 4).

At this time, the raw material resin which has been somewhat overfilled is sucked and accommodated in the resin trap 15.

After that, if the raw material resin is cured under the reduced pressure condition and then the reduced pressure is released and the upper mold 9 is removed, a good molded product D with extremely few voids can be taken out.

According to such a molding method, since it is not necessary to apply an injection pressure higher than atmospheric pressure to the molding die A, a simple die structure is sufficient, and therefore, the die manufacturing cost can be reduced and the weight can be reduced.

Further, the mold clamping is performed by reducing the pressure inside the mold clamping vacuum circuit 4.
Since it is performed using atmospheric pressure, the conventional mold clamps are no longer needed,
Since it suffices to open and close the valve of the pipe that connects the inside of the molding cavity 2 and the decompression device, the mold clamping and its release can be performed extremely efficiently.

The molding method is not limited to fiber reinforced plastics, and is suitable for molding synthetic resins having poor fluidity during melting, for example.

8 and 9 are views showing another embodiment of the molding die used in the molding method of the present invention.

This molding die A1 is configured so that a swimming pool made of glass fiber reinforced plastic can be molded seamlessly.

That is, in order to form a pool E having a box-like shape and a horizontal flange e provided on the periphery of the mouth thereof, this forming die A1 provided with a forming cavity 2 having an inverted shape of the pool E.
Has a configuration in which three split molds 21, 22, and 23 are detachably connected in the longitudinal direction.

As shown in FIG. 9, each of the split molds 21, 22, 23 is composed of a lower mold 21a, 22a, 23a and an upper mold 21b, 22b, 23c, and has a peripheral flange 24 that forms a flange c of the pool. Is the sixth
Mold clamping vacuum circuit 4 and molding vacuum circuit 7 similar to those shown in the figure
Is provided.

Further, a reinforcing flange 25 is provided on each mating surface of each split mold 21, 22, 23, and this reinforcing flange 25 portion also has a mold clamping vacuum circuit 4 similar to that shown in FIG.
And a forming vacuum circuit 7 is provided.

The injection port 11 is provided in the center of the top surface of each split mold 21, 22, 23.

Next, the operation of the above configuration will be described.

First, the lower molds 21a, 22a, 23a of the split molds are placed on the work base 26 in a butted state with each other. In order to do this accurately, the positioning members provided on the mating surfaces of the lower molds 21a, 22a, 23a and the base plate 26 and on the mating surfaces of the lower molds 21a, 22a, 23a, respectively. It suffices for the mating irregularities (not shown) to be engaged with each other.

Next, the mold clamping pipe joints 6 provided on the mating surfaces of the split molds are connected to a decompression device, and these mating surfaces are airtightly adhered to each other.

Therefore, a gel coat is applied to the outer peripheral surface of the lower mold, and a reinforcing glass fiber mat is attached to the entire surface.

After that, each upper mold 21b, 22b, 23b is sequentially covered on each lower mold 21a, 22a, 23a, and all the molds provided on the mutual mold matching surface of each upper mold 21b, 22b, 23b When the closing pipe joint 6 is connected to the pressure reducing device, the upper molds are brought into close contact with each other in an instant.

Next, when the mold clamping pipe joint 6 provided on the peripheral flange 24 of each of the lower molds 21a, 22a, 23a is connected to the pressure reducing device, the lower molds 21a, 22a, 23a and the upper mold 21b are also in the peripheral flange 24 portion. , 2
The required molding cavities 2 are formed by airtightly adhering to 2b and 23b.

Therefore, if a predetermined amount of the raw material resin is injected into the injection port 11 provided in each split mold 21, 22, 23, and thereafter the molding operation is carried out in the same manner as in the above-mentioned embodiment, even a very large pool can be easily and quickly. Can be integrally molded.

The molding die having such a configuration is, of course, not limited to a pool, and can be manufactured to integrally mold large structures having various shapes including various tanks.

[Effects of the Invention] As is clear from the above description, according to the molding method of the synthetic resin and the molding die thereof of the present invention, the filling pressure of the raw material resin can be remarkably lowered, so that the molding die need not be made robust A light and inexpensive mold is sufficient. And even though the injection pressure of the raw material resin is low, even a thin molded product,
Further, even when embedding a reinforcing material such as glass fiber, it is possible to obtain a molded product in which voids of a visible size are almost completely removed, which is an excellent practical effect.

[Brief description of drawings]

1 to 7 show an embodiment of the present invention.
1 to 5 are explanatory views of a molding process of a method for molding a synthetic resin according to the present invention, FIG. 6 is an enlarged vertical cross-sectional view of a main part of a molding die, and FIG. 7 is a sketch showing an entire configuration of a molding system. Is. FIGS. 8 and 9 show another embodiment of the molding die used in the molding method according to the present invention. FIG. 8 is a perspective view of a split type molding die assembled, and FIG. FIG. 8 is an enlarged vertical sectional view of a main part in FIG. 8. Code table 1 …… Lower mold, 2 …… Molding cavity, 2a …… Edge part,
3 ... Peripheral reinforcing material, 4 ... Mold clamping vacuum circuit (decompression seal part), 4a ... Packing groove, 5 ... Mold clamping packing, 6 ...
Mold-clamping pipe joint, 7 ... Molding vacuum circuit, 8 ... Pinch off,
9 ... Upper mold, 10 ... Suction pipe joint (degassing port), 11 ...
Injection port, 12 ... Molding device main body, 13 ... Mixing head, 14 ... Raw material hose, 14a ... Inlet joint, 14b ...
Outlet fitting, 15 ... Resin trap, 16 ... Suction pipe,
17 ... suction pipe, 18 ... intake pipe, 19 ... valve,
21,22,23 …… Split mold, 21a, 22a, 23a …… Lower mold, 21
b, 22b, 23b …… upper mold, 24 …… peripheral flange, 25 ……
Reinforcement flange, 26 ... Work base, A, A1 ... Mold, a ... Unfilled void, B ... Raw resin, C ... Glass fiber (fibrous reinforcing material), D ... Molded product, E ... … Pool

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area // B29K 105: 06

Claims (5)

[Claims] 1. Each of the following molding steps a) to c): a) An upper mold 9 having a mold wall made of a flexible material and a lower mold having rigidity at least in a flat molding surface. A step of filling a predetermined amount of raw material resin into the molding cavity 2 formed by 1. b) A step of closing the injection port 11 of the raw material resin. c) In the step b), a step of degassing the unfilled void a in the molding cavity 2 caused by the mold wall bulging due to the injection pressure of the raw material resin. A method for molding a fiber-reinforced plastic, which comprises: 2. The method for molding a fiber reinforced plastic according to claim 1, wherein a fibrous reinforcing material is embedded in the raw material resin. 3. A lower mold 1 having a rigid structure, and an upper mold 9 having a mold wall made of a flexible material at least in a flat molding surface. The mold cavity is filled with a synthetic resin. A fiber-reinforced plastic molding die having a deaeration port 10 for eliminating the air in the unfilled void a of the raw material resin in 2. 4. The upper mold 9 and / or the lower mold 1 is composed of a plurality of split molds 21, 22 and 23, and reduced pressure seal portions are formed on all of the mold mating surfaces. The molding die according to claim 3. 5. The pressure reducing seal portion is a mold clamping vacuum circuit 4 formed between a plurality of mold clamping packings 5 provided in parallel with each other on the mold matching surface.
Mold according to item.