JPH03295619A - Manufacture of fiber reinforced plastic molded object - Google Patents

Abstract

PURPOSE:To enable the molded object excellent in the impregnated condition of resin to be produced by a method in which after the stock for molding preheated FRP has been presurrized with the mold in which the temperature of a bottom force is set at least at the melting point of resin in the state where the stock is placed on the plate mold made of metal, the plate mold made of metal is separated from the bottom force in the state where prescribed pressurizing force is held, and only the plate mold is cooled. CONSTITUTION:The preform 10 formed and solidified with chopped fiber, resin powder and binder is placed on an iron plate-mold 11 and is preheated. The preform 10 in the state where it is placed on the iron plate-mold 11 is pressurized with the top force 20 in which elastic mold 21 is formed and the bottom force 30 which is set at the temperature of at least the melting point of resin and in which a lift device 31 is provided. Then after the iron plate-mold 11 has been raised with the lift device 31 and has been separated from the bottom force 30 in the state where the preform 10 is held under prescribed pressurizing force, only the iron plate-mold 11 is cooled by a cooling device 40, and after the preform 10 has been cured and stabilized, a fiber reinforced plastic object S is obtained by mold release. Consequently, its cooling time may be remarkably reduced, and the molded object is obtained at high molding cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to fiber reinforced plastic molded articles (hereinafter referred to as rFRP).
(hereinafter referred to as "molded object").

[Conventional technology]

Conventionally, in the manufacturing method of FRP molded objects, in order to impregnate the fibers with resin, the mold must be heated and cooled each time, and it takes a long time to heat up and cool the mold. Ta.

As a method to solve this problem, for example, a preform formed by molding and solidifying chopped fibers, resin powder, and a binder is sandwiched between two preheating plates made of thin metal plates, and the molding process is kept at a temperature lower than the melting point of the resin. A method for manufacturing an FRP molded body has been proposed in which cold pressing is performed to simultaneously impregnate and cool a molten resin.

[Problems to be Solved by the Invention] By the way, in the method for producing an FRP molded body as described above, the preform is preheated, and the resin impregnation and cooling are simultaneously performed in the mold by cold pressing. This eliminates the need for heating and cooling the mold temperature, and therefore allows molded products to be obtained with a high molding cycle, but the temperature of the mold in cold press is usually set 20 to 30°C lower than the melting point of the resin. As a result, the temperature of the preheated preform decreases in a short period of time, making it impossible to obtain a molded article in a good impregnated state.

The present invention was made against the background of the above-mentioned conventional technology, and it is possible to obtain a molded body with a high molding cycle, and also to obtain a molded body with good resin impregnation state and excellent strength. It is an object of the present invention to provide a method for manufacturing an FRP molded body that makes it possible to do this.

[Means to solve the problem]

In the present invention, an FRP molding material is placed on a metal plate mold and preheated, and then, while the FRP molding material is placed on the metal plate mold, the temperature of the lower mold is adjusted to the temperature of the resin. After pressurizing with a mold set above the melting point, the metal plate mold is separated from the lower mold while maintaining the FRP molding material at a constant pressure, and only the metal plate mold is cooled. The present invention provides a method for producing a fiber-reinforced plastic molded article.

[Function] According to the present invention, the FRP molding material, which has been preheated while being placed on a metal plate mold, is molded into the FR material by the mold.
Since the pressure is applied at a temperature higher than the melting point of the resin constituting the P molding material, the impregnation state of the resin is good, and the temperature of the lower mold only needs to be kept at a constant temperature higher than the melting point of the resin. Therefore, there is no need to heat or cool the lower mold, and
After pressurizing the FRP molding material with a mold, the FR
By separating the metal plate mold from the lower mold and cooling only the metal plate mold while holding the P molding material at a constant pressure, it is possible to significantly shorten the cooling time. A molded body can be obtained with a high molding cycle.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.
The present invention is not limited to this.

Figures 1 and 2 show an embodiment of the present invention, and the method for producing the fiber-reinforced plastic molded body S is a preform (fiber-reinforced plastic) molded and solidified with chopped fibers, resin powder, and a binder. The molding material) 10 is placed on an iron plate mold (metal plate mold) 11 and preheated, and then the iron plate mold 11 is placed as shown in FIGS. 1(a) and (b).
The preform 10 is pressurized with the upper mold 20 in which the elastic body 21 is formed and the lower mold 30 which is set at a temperature higher than the melting point of the resin and equipped with a lift device 31. In addition, while holding the preform 10 under a constant pressure, as shown in FIG. 1(c), the iron plate mold 11 is lifted up by a lift device 31 and separated from the lower mold 30, and then only the iron plate mold 11 is placed in a cooling device 40. After the preform 10 is cured and stabilized, the preform 10 is demolded to obtain a fiber-reinforced plastic molded product S.

As a method for manufacturing the preform 10, for example, chopped fibers such as carbon fibers or glass fibers are first uniformly adsorbed onto a porous preform mold (not shown), and then resin powder is sprayed to adsorb the fibers.

Furthermore, a binder is applied to solidify the preform,
dry. Thereby, a preform 10 in which chopped fibers and resin powder are uniformly blended is obtained.

Then, this preform 10 is placed into an iron plate mold 1 whose mold surface is formed in the same shape as the back surface 10a of the preform IO.
1 and is preheated in a heating furnace (not shown) to melt the resin, and then pressurized with an upper mold 20 and a lower mold 30.

Further, the preheating temperature needs to be higher than the melting point (Tm) of the resin constituting the preform 10, and is usually Tm+15°C to Tm+35°C, preferably Tm+20°C.
It is within the range of °C to Tm+30 °C.

Furthermore, the preheating time is usually 10 to 15 minutes,
Preferably it is 5 to 10 minutes.

Furthermore, the pressing force of the preform 10 is usually 20
~50 kg/cii, preferably 20 to 30 kg/d, and the pressurization time of the preform IO is usually 3 to 5 minutes.
Preferably it is 2 to 3 minutes.

Although only one preform 10 is used in this example, it is not necessarily limited to this. For example, two or more layers of preforms 10 may be stacked and placed on the iron plate mold 11. It is.

The upper die 20 is formed with an elastic body 21 having a die surface having the same shape as the surface lOb of the preform 10, so that even when deep drawability is required, sufficient pressure can be applied to the deep drawing part. It becomes possible to obtain a fiber-reinforced plastic molded article S having excellent appearance and strength.

The material of the elastic body 21 is preferably silicone rubber or fluororubber, which has excellent heat resistance and mold release properties.

Furthermore, the set temperature of the elastic body 21 is usually Tm-30.
°C-Tm-10°C, preferably Tm-25°C to Tm-
The reason why the temperature is within the range of 15°C and below the melting point (Tm) of the resin is that the elastic body itself is a heat insulator, and Tm
This is because even if the temperature is below Tm, the temperature will not drop as rapidly as when it is brought into direct contact with an iron plate, and if the temperature is above Tm, the elastic body must be cooled.

Although the elastic body 21 is used in this embodiment, if deep drawability is not required, it is not necessarily limited to the elastic body (it is also possible to use a normal mold).

The lower mold 30 is made by pressing the preform 10 placed on the iron plate mold 11 with the upper mold 20 and the lower mold 30, and then lifting the preform 10 upward while maintaining a constant pressure. A lift device 31 for separating the device from the device 30 is provided inside.

Furthermore, although a damper is used as the lift device 31 in this embodiment, it is not necessarily limited to this, and a cushion bin 32 may be interposed between the iron plate mold 11 and the lower mold 30 as shown in FIG. It is also possible to separate the iron plate mold 11 from the lower mold 30 by using the steps shown in FIG. can.

Note that the set temperature of the lower mold 30 needs to be higher than the melting point (Tm) of the resin constituting the preform 10.
Usually Tm+3℃~Tm+10℃1 Preferably Tm+
It is within the range of 3°C-Tm+5°C.

Further, the pressing force of the preform 10 when the iron plate mold 11 is separated from the lower mold 30 is usually 5 to 20 kg/ci.
a, preferably 5 to 10 kg/d.

The cooling device 40 connects an air compressor 41 to a connecting tube 42.
The compressed air sent out through the nozzle 43 is injected onto the back surface 11b of the iron plate mold 11 separated from the lower mold 30 to forcefully air-cool the preform 10.
By this air cooling, it is necessary to cool the preform 10 so that the temperature of the preform 10 becomes Tm-20°C or less within 2 to 3 minutes.

Further, the amount of compressed air and the air pressure may be appropriately selected depending on the shape, size, etc. of the preform 10.

In this embodiment, an air cooling method is used as the cooling means, but it is not necessarily limited to this, and for example, a water cooling method can also be used.

As described above, according to this embodiment, the preform 1 is preheated while being placed on the iron plate mold 11.
0 is pressurized by the upper mold 20 and the lower mold 30 at a temperature higher than the melting point of the resin constituting the preform 10, the impregnation state of the resin is good, and the temperature of the lower mold 30 is higher than the melting point of the resin. Since it only needs to be kept at a constant temperature, there is no need to heat or cool the lower die 30, and after the preform 10 is pressurized by the upper die 20 and the lower die 30, the preform 10 is held at a constant pressure. By separating the iron plate mold 11 from the lower mold 30 while holding it and cooling only the iron plate mold 11, it becomes possible to significantly shorten the cooling time, and a fiber-reinforced plastic molded product S can be obtained with a high molding cycle. Become something.

Hereinafter, in order to explain this embodiment in more detail, it will be explained in comparison with a conventional example.

First, by the method shown above, the reinforced chopped fiber and 35
#6 - The preform molded and solidified with nylon powder and binder is placed on an iron plate mold and heated at 240°C in a heating furnace.
After being preheated to , the preform was placed on the iron plate mold, and the upper mold had a silicone mold kept at a temperature of 190°C, and the lower mold was kept at a temperature of 215°C. 30, heated and pressurized for 3 minutes at a pressure of 20 kg/cd, and then, while holding the preform at a pressure of 5 kg/aj, lifted the iron plate mold with a lift device and separated it from the lower mold, and then removed only the iron plate mold. The cooling device reduces the air flow to 1.0rrf/min and the air pressure to 3.2kg/d.
Compressed air was blown onto the back side of the iron plate mold for forced air cooling, and after the preform had hardened and stabilized, it was demolded to obtain a fiber-reinforced plastic molded product.

At that time, the temperature of the preform was monitored and found that it was 235°C after 3 minutes and 190°C after 15 minutes.

The fiber-reinforced plastic molded article obtained as described above is
The resin impregnation state was good and the strength was excellent (
(hereinafter referred to as "this example").

Next, when cold pressing was performed under the same conditions as in this example, without cooling the iron plate mold and keeping the temperature of the lower mold constant at 190°C, the temperature of the preform reached 190°C in 30 seconds, resulting in good impregnation. A molded article in good condition was not obtained (hereinafter referred to as "comparative example").

A comparison of the physical properties of this example and a comparative example is shown in Table 1, and the relationship between preform temperature and molding time is shown in Figures 3 and 4.
As shown in the figure.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to obtain a fiber-reinforced plastic molded product with a high molding cycle, and also to obtain a molded product with excellent strength by improving the resin impregnation state. A method for manufacturing a fiber-reinforced plastic molded article can be provided.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of a mold in each step for explaining the method for manufacturing a fiber-reinforced plastic molded article according to an embodiment of the present invention, and FIG. It is a figure showing the relationship between preform temperature and molding time. 10 Nib form (fiber-reinforced plastic molding material) 11: Iron plate type (metal plate type) 20: Upper mold 21: Elastic body 30: Lower mold 31: Lifting device 40: Cooling device S: Fiber-reinforced plastic molded body No. 1 figure

Claims (1)

[Claims] (1) A fiber-reinforced plastic molding material is placed on a metal plate mold and preheated, and then a lower mold is placed while the fiber-reinforced plastic molding material is placed on the metal plate mold. After pressurizing with a mold whose temperature is set above the melting point of the resin, the metal plate mold is separated from the lower mold while maintaining the fiber-reinforced plastic molding material at a constant pressure, and the metal plate mold is separated from the lower mold. A method for producing a fiber-reinforced plastic molded article, characterized by cooling only the plate mold.