JPH05318488A - Molding die - Google Patents

Abstract

PURPOSE:To manufacture a self-heat developing type molding die suitable to be used as a molding die for a prepreg which can mold any sizes of prepregs. CONSTITUTION:A molding die is constituted of a face-shaped electric heat developing body and a prepreg laminate cured body. The dimension, accuracy and the like of the prepreg are different for different kinds of reinforcing material, and the prepregs suitable for the purposes are used in the subject molding die, and in the case particularly high dimension accuracy is required, a carbon fiber prepreg is desirably used. The molding die is manufactured by laminating the face-shaped electric heat developing body and the prepreg into the desired mold shape, and then curing thermosetting resin being impregnated in the prepreg and integrating the face-shaped electric heat developing body and the prepreg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die, and more particularly to a self-heating molding die made of a specific material.

[0002]

2. Description of the Related Art Prepreg is a laminated molding material in which a reinforcing material such as glass fiber, woven cloth, mat, carbon fiber, etc. is impregnated with a thermosetting resin, and then semi-dried until tackiness disappears. It is used as a molding material in various fields.

The molding of a prepreg is generally carried out by molding a desired mold and then heat-treating it in a heating furnace as it is to cure the impregnated thermosetting resin.

[0004]

However, in the case of the above-mentioned molding method, although there is no particular problem in the case of a small-sized molded product, a large-sized heating furnace commensurate with it is required in the case of a large-sized molded product. Therefore, the size of the molded product is limited.

The present invention has been made in view of the above circumstances, and provides a self-heating type molding die that can be molded into any size without the need for a heating furnace for curing a prepreg. It is intended.

[0006]

That is, the gist of the present invention resides in a mold for molding which is composed of a laminated hardened body of a sheet-like electric heating element and a prepreg.

The present invention will be described in detail below. The molding die of the present invention comprises a laminated hardened body of a sheet-like electric heating element and a prepreg.

The sheet-like electric heating element uses, for example, a carbon fiber material such as carbon fiber cloth, carbon fiber paper, carbon fiber tape woven fabric, carbon fiber prepreg, carbon fiber felt, or carbon black as a heating element. Any planar electric heating element may be used in the molding die of the present invention.

As the prepreg, various kinds of prepregs such as glass fiber prepreg and carbon fiber prepreg are known depending on the kind of the reinforcing material, and even if the same reinforcing material is used, various grades of prepreg are produced due to the difference in the weaving method. Are commercially available.

Although the dimensional accuracy of the prepreg differs depending on the kind of the reinforcing material, an appropriate prepreg is used according to the purpose in the molding die of the present invention. Particularly, when high dimensional accuracy is required, it is preferable to use a carbon fiber prepreg.

In the molding die of the present invention, a sheet-like electric heating element and a prepreg are laminated in a desired die shape, and then the thermosetting resin impregnated in the prepreg is cured to form a sheet-like electric heating element. Obtained by integrating with prepreg.

The above-mentioned mold shape can be an arbitrary mold shape such as a concave shape or a round shape, if desired. in this case,
If necessary, an existing molding die can be used.

The order of laminating the sheet-like electric heating element and the prepreg is not particularly limited, but when a plurality of layers of prepreg are used, the sheet-like electric heating is placed at an appropriate position in consideration of the thermal efficiency of the inner surface of the molding die. It is necessary to stack the body.

Further, the sheet-like electric heating element and the prepreg are
In each case, two or more layers may be used if necessary. Particularly in the case of a molding die that requires high dimensional accuracy, it is desirable to prevent warpage by using a plurality of layers of different grades depending on the prepreg used.

The thermosetting resin impregnated in the prepreg is easily cured by laminating the sheet-like electric heating element and the prepreg in an arbitrary mold shape and then performing heat treatment while maintaining the mold shape. be able to.

The above-mentioned heat treatment can be performed using a heating furnace, but can also be performed using stacked planar electric heating elements. The heating of the planar electric heating element can be easily carried out by applying an alternating voltage to the electrodes provided on the heating element.

In any of the above-mentioned heat curing methods, it is preferable to carry out the treatment under a vacuum condition by performing a treatment such as removing excess thermosetting resin that has exuded according to a known prepreg curing method.

The molding die of the present invention is particularly preferably used as a prepreg molding die. Then, the molding of the prepreg, if necessary, by applying a suitable release agent in the molding die, or after laying a release film made of a heat-resistant resin, fit a predetermined prepreg into the mold, It is carried out by a method of heating the sheet-like electric heating element to heat and cure the thermosetting resin impregnated in the prepreg.

[0019]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 After the inner surface of a concave aluminum mold having a length of 600 mm, a width of 500 mm and a depth of 60 mm was cleaned and a mold release agent was applied,
A surface ply (prepreg manufactured by Fiberlight Co., USA; trade name MXG7644) according to the shape in the above mold.
-1) was placed. After that, a porous polyfluorotetraethylene release film, a nylon peel ply, and a breather were laminated in the order shown.

Then, the whole laminate was covered with a nylon film, a vacuum bag forming apparatus was attached, and the surface ply was brought into complete contact with the aluminum mold by keeping it at room temperature for 1 hour under a reduced pressure of 720 mmHg. Then, the temperature was returned to room temperature, and the nylon film and each lamination aid were removed.

Next, three layers of plain weave carbon fiber cloth prepreg (trade name MXG-7620 / 2534, manufactured by Kasei Fiberlight Co., hereinafter referred to as "prepreg (1)") having a thickness of 0.243 mm were laminated, and a thickness of 0.432 was further obtained.
mm Crowfoot satin weave carbon fiber cloth prepreg (Chemical Fiber Light Co., Ltd. product name MXG-7620 /
2548, hereinafter referred to as “prepreg (2)”) was laminated in four layers.

Then, a thermocouple was inserted into the center of the laminate in the thickness direction, and each lamination aid was laminated according to the same procedure as described above, and the laminate was placed in a heating furnace while being kept under a reduced pressure of 720 mmHg by a vacuum bag forming apparatus. The mixture was put in, heated at a rate of 2 ° C./min in a depressurized state, and kept at 40 ° C. for 1 hour for defoaming. Temperature control was performed with a thermocouple.

After the completion of defoaming, the mixture was cooled to 38 ° C. under reduced pressure, taken out from the heating furnace and returned to normal pressure, and the nylon film, each lamination aid and thermocouple were removed.

The defoamed laminate had a thickness of 0.73
Four layers of 7 mm plain weave carbon fiber cloth prepreg (trade name MXG-7620 / 2577 manufactured by Kasei Fiberlight Co., Ltd., hereinafter referred to as "prepreg (3)") and a thickness of 0.229.
8 mm satin weave glass fiber cloth prepreg (product name MXB-7620 / 778 manufactured by Kasei Fiberlight Co., Ltd.)
1, hereinafter referred to as "prepreg 4"), a planar electric heating element is laminated thereon, and further 1 layer of the above-mentioned prepreg (4) and 4 layers of the prepreg (3) are laminated. did.

Each of the above laminating aids was laminated on the above-mentioned laminated body according to the same procedure as described above, and the laminated bag was formed by a vacuum bag forming apparatus.
It was sucked under a reduced pressure of 20 mmHg. Then, in order to perform the same defoaming treatment as described above, the temperature was raised to 83 ° C. by placing it in a heating furnace and holding it for 1 hour, and further raised to 93 ° C. In that state, it was held for 2 hours to be cured. After the completion of curing, the system was cooled to 38 ° C. under reduced pressure and returned to normal pressure to obtain a cured molding die. This was placed in a heating furnace and post-cured at 180 ° C. for 2 hours to obtain a molding die of the present invention.

The sheet-shaped electric heating element of the obtained molding die has 10 parts.
When an AC voltage of 0 V was applied and the temperature was measured at arbitrary 9 points over almost the entire area, it was confirmed that all the points had almost the same temperature and a uniform temperature distribution was obtained.

Example 2 The same procedure as in Example 1 was carried out until the planar electric heating element was laminated, and then one layer of prepreg (4) having a thickness of 1.118.
mm triple plain weave glass fiber cloth prepreg (product name MXB-7620 / 1597 manufactured by Kasei Fiberlight Co., Ltd.,
Hereinafter, after four layers of "prepreg (5)" were laminated, a molding die of the present invention was obtained by the same method as in Example 1.
The same temperature measurement as in Example 1 was performed, and it was confirmed that a uniform temperature distribution was obtained.

Example 3 The molding and die of the present invention was obtained by performing the same lamination and heating as in Example 1 except that the planar electric heating element in the laminate was used instead of using the heating furnace. The temperature of the obtained molding die was measured in the same manner as in Example 1, and it was confirmed that a uniform temperature distribution was obtained.

[0030]

INDUSTRIAL APPLICABILITY According to the present invention described above, there is provided a self-heating type molding die which is preferably used as a molding die for a prepreg and can be molded into any size. Therefore, the industrial value of the present invention is great.

Claims (1)

[Claims] 1. A molding die characterized by comprising a laminated hardened body of a sheet-like electric heating element and a prepreg.