JP3440249B2 - Prepreg curing method and apparatus used therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of curing a prepreg and an apparatus used for the method.

[0002]

2. Description of the Related Art In recent years, a so-called "composite material", which is a composite of two or more kinds of materials in a form utilizing their excellent functions, has been attracting attention. As such a composite material, for example, fiber reinforced plastic (FRP) is well known and is used in a wide range of fields from leisure goods and sports goods to aircraft, space industry equipment and the like.

The FRP is usually manufactured as follows. That is, first, carbon fibers, glass fibers, aramid fibers, etc. are formed into a woven fabric, a non-woven fabric, etc., cut into a sheet shape, a tape shape, etc., and then impregnated with a resin to obtain a prepreg. As shown in FIG. 2, the prepregs are laminated as they are, and along a predetermined mold 1, as shown in FIG. 2, the prepreg 2 on the mold 1 is covered with a vacuum bag 3 without any gaps and then placed in the autoclave 4. Load it.
Then, in the autoclave 4, the heater 5 and the blower 6 are operated, hot air is circulated as shown by an arrow P, and the inside of the vacuum bag 3 is evacuated by the vacuum pump 8. The prepreg 2 is cured while deaerating the air existing at the interface between the prepreg 2 and the mold 1. And autoclave 4
The desired FRP molded product can be obtained by taking out the cured product from the mold and removing it from the mold 1.

[0004]

However, as described above, in the curing method using the autoclave 4, the prepreg 2 along the mold 1 must be put in the vacuum bag 3 and sealed. There is a problem that the work is very complicated. In particular, when the molded product to be obtained is small, as shown in FIG. 3, a large number of prepregs 2 are loaded side by side in an autoclave 4 and are collectively cured, but at this time, Since each prepreg 2 along the mold 1 must be individually sealed with the vacuum bag 3 and connected to the vacuum pipe 9, which requires a great deal of work, its improvement is strongly desired.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method by which a prepreg can be easily cured by a completely new method without using an autoclave, and an apparatus used therefor.

[0006]

In order to achieve the above object, the present invention is a method for curing a prepreg formed in a predetermined shape along a mold, wherein a plurality of the prepregs are accommodated at predetermined intervals. The step of loading the treated inner tank into the processing tank, the step of decompressing the inside of the processing tank to degas the gas contained in the prepreg, and the step of pressurizing the inside of the processing tank to form the prepreg into the formwork. The first gist is a prepreg curing method including a step of curing the prepreg by circulating hot air in the inner tank and curing the prepreg in a predetermined shape along the mold. An apparatus for storing a plurality of the above-mentioned prepregs at a predetermined interval inside, and a hot-air circulation path including a processing tank with an opening / closing lid, a heating means and a blowing means, the end of which is connected to the processing tank. Can The internal tank, which is set in such a manner that the internal space is in communication with the end of the hot air circulation path, is loaded into the processing tank, a decompression means for decompressing the inside of the processing tank, and a pressurizer for pressurizing the inside of the processing tank. A second gist is a prepreg curing device including a pressure means.

[0007]

That is, the present invention uses a special treatment tank provided with a pressure reducing means, a hot air circulating means and a pressurizing means, and accommodates a plurality of prepregs along the form in the inner tank and The prepreg is loaded in the above treatment tank, and is not sealed individually in a vacuum bag, but is evacuated as it is, and the prepreg is cured by heating and pressurizing. Therefore, according to this method, unlike the conventional method using an autoclave, it is not necessary to individually seal each prepreg with a vacuum bag, and the processing efficiency can be greatly improved. Moreover, in the conventional method,
Since the degree of sealing by the vacuum bag varies from prepreg to prepreg, some prepregs may be cured with insufficient deaeration, resulting in uneven quality. However, according to the present invention, a plurality of prepregs may be used. This is advantageous in that the quality of the obtained cured product becomes uniform because the pressure reduction, heat and pressure treatment are performed under the same conditions.

Next, the present invention will be described in detail based on examples.

[0009]

1 is a block diagram showing an embodiment of the present invention. In the figure, 10 is a vertical processing tank, which is adapted to be hermetically sealed by fitting a lid 11 provided on the upper portion.
Then, one end side of the hot air circulation passage 15 including the heat exchanger 13 and the blower 14 is communicated with the center of the bottom portion of the treatment tank 10, and the other end side of the hot air circulation passage 15 is communicated with the side portion of the bottom portion of the treatment tank 10. ing.

The upper end of the hot air circulation passage 15 protruding upward from the center of the bottom of the processing tank 10 has an inner tank pedestal 1
6 is formed in this part, and a taper cone 17 is formed at the bottom of this part.
An inner tank 18 having a bottom and having a bottom is detachably loaded.

The inner tub 18 includes a base portion 20 forming a header portion 19, a tray 21 having a multi-layered bottom surface and a perforated bottom plate 21 and a perforated cover plate 22 for covering the uppermost tray 21. It is composed of. Then, in each tray 21, a plurality of prepregs 2 along the molding frame 1 can be placed and accommodated at predetermined intervals.

On the other hand, the processing bath 10 of the hot air circulation path 15
A pressure adjusting pipe 25 is connected between the inside and the blower 14 so that the pressure in the processing tank 10 can be appropriately changed. That is, this pressure adjusting pipe 2
5 includes a vacuum pipe 26 including a vacuum valve 26, a vacuum release valve 27, a trap 28, and a vacuum pump 29, and a pressurizing valve 3.
1, compressor 32, release valve 33, silencer 34
Is connected to the pressurizing pipe 35. 36
Is a safety valve, 37 is a vacuum gauge, and 38 is a vacuum sensor. Further, 39 is a pressure gauge, and 40 is a pressure sensor.

Using the above apparatus, the prepreg can be cured, for example, as follows. That is,
First, the prepregs 2 along the form 1 are placed on each tray 21 of the inner tank 18 at a predetermined interval, and the trays 21 are multi-tiered on the base 20 to open the upper surface of the uppermost tray 21. The lid 22 is fitted to and the whole is fixed. Then, the inner tank 18 is loaded into the processing tank 10 and fixed to the inner tank support 16. In this state, the lid 11 is closed to seal the inside of the processing tank 10, and the vacuum pump 29 is operated to open the vacuum valve 26 to depressurize the inside of the processing tank 10. As a result, in the inner tank 18, the air contained in the prepreg 2 itself and the prepreg 2
And the air existing at the interface of the mold 1 are sufficiently degassed. Next, the vacuum valve 26 is closed to stop the vacuum pump 29, and the pressurizing valve 31 is opened to open the compressor 32.
Is operated to increase the pressure inside the processing tank 10. At the same time, the heat exchanger 13 and the blower 14 are operated to change the pressurized air flow into hot air and circulate it as shown by arrow A. That is, the pressurized flow is blown into the heat exchanger 13 by the blower 14, heated to a predetermined temperature by the heat exchanger 13, and then flows into the header portion 19 of the inner tank 18,
The inside of each tray 21 of the inner tank 18 rises, is jetted from the cover plate 22, descends along the inner peripheral surface of the treatment tank 10, and is returned to the suction port side of the blower 14. As a result, the hot air forcedly circulated and the prepreg 2 in the inner tank 18 repeatedly come into contact with each other, and the prepreg 2 is cured. After holding this state for a certain period of time,
The release valve 33 is opened to return the inside of the processing tank 10 to normal pressure, and the lid 1
1 is opened and the inner tank 18 is taken out of the processing tank 10. Then, the cured body of the prepreg 2 is taken out from each tray 21 together with the mold 1, and then the mold is removed. The cured products thus obtained are uniformly cured in a state of being sufficiently deaerated, have high quality, and are widely used in various fields.

In the above embodiment, the depressurizing conditions in the processing tank 10, the temperature of the hot air to be circulated and the pressurizing conditions are
It is appropriately set depending on the shape and material of the prepreg to be hardened, the desired shape of the molding, and the like. For example, when curing the following prepreg 2, the processing conditions were preferably set as follows.

<Specifications of prepreg 2> Material: Reinforcing core: carbon fiber Impregnation resin: Heat-resistant epoxy resin Shape: 2 mm thick sheet

<Curing conditions> Degree of vacuum at reduced pressure: 1 to 200 Torr, 9 in particular
10 Torr is suitable. Decompression time: 3 to 30 minutes, preferably 3 to 5 minutes. Pressure at pressurization: 3 to 10 kg / cm ² , preferably 7 to 8 kg / cm ² . Pressurization time: 150 to 180 minutes. Hot air temperature …… 130-140 ℃

Further, in the above embodiment, the inner tank 18 constructed by stacking the trays 21 in multiple stages is used, but the shape of the inner tank 18 is not limited to this, and a plurality of prepregs 2 are provided. Any type can be used as long as it can be accommodated at a predetermined interval and can communicate the inside with the hot air circulation path 15. However, as in the above-described embodiment, the header portion 19 is provided at the bottom of the inner tank 18 so that the hot air passing through the inner tank 18 moves in the vertical direction in a laminar flow state so that the prepreg 2 is evenly distributed. It is suitable from the viewpoint of curing. Of course, it is possible to use the one set so that the hot air is uniformly dispersed and moved from the center side of the inner tank 18 to the side surface direction or the opposite direction. The processing tank 10 also uses a vertical type in the above embodiment,
A horizontal type may be used and the inner tank 18 may be taken in and out in the left-right direction.

Furthermore, the direction in which the pressurized hot air is forcedly circulated is not limited to the direction of the above embodiment, but may be reversed. Further, the circulation direction may be reversed every predetermined time.

[0019]

As described above, according to the present invention, a special treatment tank provided with a pressure reducing means, a hot air circulating means and a pressurizing means is used, and a plurality of prepregs along the form are accommodated in the inner tank. Then, the inner tank is loaded into the processing tank, and the individual prepregs are cured by directly reducing the pressure as they are without sealing with a vacuum bag and then heating and pressurizing the prepregs. Therefore, according to the present invention, unlike the conventional method using an autoclave, it is not necessary to individually seal each prepreg with a vacuum bag, and the processing efficiency can be greatly improved. Moreover, in the conventional method, since the degree of sealing by the vacuum bag varies from prepreg to prepreg, some prepregs may be cured with insufficient deaeration, which may cause variations in quality. According to this, a plurality of prepregs are collectively subjected to depressurization / heating / pressurization treatment under the same conditions, and thus there is an advantage that the quality of the obtained cured product becomes uniform.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an example of a conventional apparatus used for curing a prepreg.

FIG. 3 is an explanatory diagram of a problem of the conventional device.

[Explanation of symbols]

1 formwork 2 prepreg 10 treatment tanks 11 lid 13 heat exchanger 14 blower 15 hot air circulation 18 inner tank 25 Pressure adjustment piping 26 Vacuum valve 29 Vacuum pump 30 vacuum piping 31 Pressurizing valve 32 compressor 35 Pressurized piping

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B29C 35/04 B29C 51/10 B29C 67/12-67/18

Claims (2)

(57) [Claims] 1. A method of curing a prepreg molded in a predetermined shape along a molding frame, the method comprising loading an inner tank containing a plurality of the prepregs at predetermined intervals into a processing tank. , A step of depressurizing the inside of the processing tank to degas the gas contained in the prepreg, and pressurizing the inside of the processing tank to form the prepreg along the mold and hot air into the inner tank. And a step of curing the prepreg by circulating the prepreg. 2. An apparatus for curing a prepreg molded into a predetermined shape along a molding frame, which comprises a processing tank with an opening / closing lid, a heating means and a blowing means, and is connected to the processing tank. And a hot air circulation path to which the parts are connected, and a plurality of the above prepregs are set in the interior so as to be able to be accommodated at predetermined intervals, and the internal space is connected to the end of the hot air circulation path and is loaded into the processing tank. A prepreg curing apparatus, comprising: an inner tank to be treated, a decompression means for decompressing the inside of the processing tank, and a pressurizing means for pressurizing the inside of the processing tank.