JPS61144332A - Molding device of fiber reinforced plastic - Google Patents

Abstract

PURPOSE:To constitute the title device so that the temperature of the inside of a molded article is made to increase uniformly in a short period of time and taking out pressurizing timing is made easy, by making a material to be molded, which is made of CFRP, heat internally by making high frequency generate within a pressure tank. CONSTITUTION:A molding device 10 of CFRP is constituted of a pressure tank 2, pressurizing device 3 connected with the pressure tank 2 pressurizing the inside of the pressure tank 2, a pair of electrodes 6 placing a material to be molded 7 provided within the pressure tank 2 between them, oscillator 4 generat ing high frequency on an electrode 6 and cable 5 connecting between the oscilla tor 4 and electrode. The high frequency oscillated from the oscillator 4 generate high-frequency electric field through a cable 5. Then molding is performed by pressurizing the inside of the pressure tank 2 by making use of the pressuriz ing device 3 at the time when the CFRP material to be molded 7 has become the optimum temperature (for example 160 deg.C) for curing thermosetting resin constituting the CFRP material to be molded 7 placed between the electrodes 6 by making the CFRP material to be molded heat.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a molding device for a rotating body made of fiber-reinforced plastic.

[Technical Background of the Invention] Generally, when a rotating body is rotated, hoop stress (circumferential stress) δI is generated in the rotating body due to centrifugal force. This hoop stress δI is generally δa-(77g)・■2 ・・・・・・・・・(1
) However, γ: specific weight of the rotating body material g=gravitational acceleration V; expressed as the circumferential speed of the rotating body.

In addition, if the tensile strength δB of the rotating body material is determined, the critical circumferential speed Vc of the rotating body is Vc = gB/γ ・Sf (2) where S': is expressed as a safety factor. .

Therefore, when the circumferential speed of the rotating body is increased, the hoop stress δI increases in proportion to the square of the circumferential speed.

In this case, from the viewpoint of safety of the rotating body material, it is required that δB>δI. If the condition of δB〉δ− cannot be satisfied, it is necessary to select a material, and recently, specific strength (δe
/γ) There is a tendency to use fiber reinforced plastics (hereinafter referred to as FRP), particularly carbon fiber reinforced plastics (hereinafter referred to as CFRP).

Various methods are generally used to mold the components of the FRP rotary body, including an autoclave method, a press method, and a filament winding method (F, W method).

A conventional FRP molding apparatus will be explained with reference to FIG. Note that FIG. 3 is a schematic cross-sectional view of the device.

The FRP molding apparatus 1 shown in FIG. 3 includes a pressure tank 2, a pressure device 3 connected to the pressure tank 2 for pressurizing the inside of the pressure tank 2, and It consists of a heating device 8 connected to the pressurized tank 2 to raise the temperature.

Inside the pressurized tank 2, a rotary cylinder 7, for example, as an FRP molded object is placed on a support (not shown).

[Problems in the background art] Equipment using various methods such as autoclaves, presses, and filament winding are used to mold the above-mentioned FRP, but all of them involve applying heat to the thermosetting resin used as the matrix of FRP. In addition, so-called external heating such as hot air or electric heaters is used to harden the matrix. However, the heat...
, because heat is transferred from the surface of an object to the inside by conduction, so in the case of FRP, especially objects with low thermal conductivity such as thermosetting resin, it takes a long time for the heat to reach the deep part. There was a drawback.

Furthermore, in order to actually form the material, it is necessary to heat it and at the same time apply pressure after reaching a certain temperature. For this reason, when conventional external heating is used, the internal temperature of the molded product does not rise uniformly, especially in thick parts, making it difficult to apply pressure at the right time, and there is a risk that predetermined design conditions may not be satisfied.

[Purpose of the Invention] The present invention was made in view of the above circumstances, and its purpose is to heat and harden the thermosetting resin that is the matrix in the molding of a rotating body made of fiber reinforced plastic (FRP), especially CFRP. It is therefore an object of the present invention to provide an FRP molding apparatus that allows the temperature inside the molded product to rise uniformly in a short time and allows the timing of pressurization to be adjusted.

[Summary of the Invention] In order to achieve the above object, the present invention provides a pressurizing tank into which a fiber-reinforced plastic molded object is inserted, a pressurizing device that pressurizes the inside of this pressurizing tank, and a pressurizing device that pressurizes the inside of this pressurizing tank. an oscillator disposed outside the pressurized tank to generate high frequency; a pair of electrodes provided facing each other so as to sandwich the object to be molded; and an oscillator that applies voltage to the electrodes to energize them. , is characterized by consisting of a cable connecting the oscillator and the electrodes. According to this invention, since the CFRP molded object generates internal heat, it can be uniformly heated in a short time.

In addition, since it can be locally heated and molded, it can be efficiently molded without affecting other parts, and at the same time it can be bonded using a thermosetting resin.

[Embodiment of the Invention] An embodiment of the FRP molding apparatus according to the present invention will be described below with reference to FIG.

The CFRP molding equipment @10 shown in FIG. 1 includes a pressurized tank,
A pressurizing device 3 connected to the pressurizing tank 2 for pressurizing the inside of the pressurizing tank 2, a pair of electrodes 6 that sandwich the molded object 7 provided in the pressurizing tank 2, and the electrodes 6 It consists of an oscillator 4 that generates a high frequency wave, and a cable 5 that connects the oscillator 4 and an electrode 6. A rotating cylinder 10 as a CFRP molded body is placed on a support (not shown) between a pair of electrodes 6 arranged opposite to each other.

Next, the principle of high frequency dielectric heating, which is the basis of the present invention, will be explained. Many molecules that make up dielectric materials (insulators) can be thought of as a collection of electrical dipoles with equal amounts of positive and negative charges.

As shown in Figure 2, when a dielectric material is placed in a high-frequency electric field, the high-frequency voltage changes its polarity periodically, causing each molecule of the dielectric material to undergo a reversal motion, causing internal friction between adjacent molecules. I get a fever.

The heat ff1Pv generated per unit volume per second in the heated object by dielectric heating is expressed by the following equation.

Pv=(5/9)r ・ε-tanδ(V/d)2x
10"(W/C1l') [: Oscillation frequency (MHz) ε: Dielectric constant of heated object (-) tan δ Dielectric loss tangent of heated object (-) V Applied voltage (V) d Electrode spacing (am) Also This is because high frequency dielectric heating is also called internal heating and is a heating method in which the CFRP itself of the molded object generates heat.

Next, the operation of this FRP molding apparatus 10 will be explained.

The high frequency oscillated from the oscillator 4 generates a high frequency electric field at the electrode 6 via the cable 5. The CFRP molded body 7 placed between the electrodes 6 generates heat according to the above principle.
When the thermosetting resin constituting the CFRP molded object 7 reaches the optimum temperature (for example, 160° C.) for curing, the pressurizing device 3 is used to press the electrode 6 and the CFRP molded object 7 inside. Pressurize the inside of the pressure tank 2 (for example, 7 kQ/
cd 90 minutes) and shape.

By using such a CFRP molding device 1, CF
Since the RP molded body 7 itself generates heat, it is possible to manufacture a uniform product without losing the timing of pressurization.

It is also possible to locally heat and press only the necessary parts to form and bond them.

[Effects of the Invention] As detailed above, the present invention has the following effects.

(1) During CFRP molding, the CFRP molded body internally generates heat uniformly in a short period of time, making it easy to time the pressurization and molding uniform CFRP, and at the same time speeding up the molding.

(2) Since CFRP can be locally heated, efficient molding and bonding are possible.

[Brief explanation of the drawing]

Fig. 1 is a conceptual cross-sectional view showing an embodiment of the FRP molding apparatus according to the present invention, Fig. 2 is a schematic diagram showing the principle of high-frequency dielectric heating which is the basis of the present invention, and Fig. 3 is a conventional FRP molding device. FIG. 2 is a conceptual cross-sectional view showing the device. 1.10...FRP molding device 2......Pressure tank 3...
・・・・・・Pressure device 4・・・・・・・・・・Oscillator 5・・・・・・・・・・・・Cable 6・・・・・・・・・・・・Electrode 7... CFRP molded object 8...
・・・・・・・・・Patent attorney representing heating device Sasu Suyama - Figure 1

Claims (1)

[Claims] (1) A pressurized tank into which a fiber-reinforced plastic molded object is inserted, a pressurizing device that pressurizes the inside of this pressurized tank,
an oscillator disposed outside the pressurizing tank that generates high frequency waves in the pressurizing tank; electrodes provided facing each other so as to sandwich the molded object; and the oscillator energizing the electrodes. A fiber-reinforced plastic molding apparatus comprising: a cable connecting the electrodes.