JPS6143541A - Manufacture of frp parts - Google Patents

Abstract

PURPOSE:To contrive an improvement in strength of a product by preventing generation of a resin-rich part, by a method wherein a fibrous material is kept clad beforehand on the surface of a part of a molding die and then hot pressing is performed by charging the molding die with a prepreg sheet. CONSTITUTION:After glass short fibers 4...4 have been made to clad to recessed parts 1a, 1b of a top force 1 prior to press molding and prepreg sheets 3...3 have been set on a bottom force 2, hot pressing of the above sheets 3...3 is performed while they are being heated by the top force 1 and the bottom force 2 by moving the top force 1 downward. With this construction, as it becomes that the above glass short fibers 4...4 exist densely on the upper side of glass long fibers 9...9 even if the glass long fibers 9...9 are made into a state wherein they are gathered to protrusion 2a, 2b sides in the bottom force 2 as the glass short fibers 4...4 have been clad, generation of a resin-rich part wherein the glass fibers are not existed is prevented and it becomes that a product which has no deviation in its composition, therefore, and is uniform strengthwise can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing FRP parts having uneven parts using a laminated material of prepreg sheets containing long fibers, such as engine mounts in automobiles. It is used for manufacturing members, etc.

(Prior art) In recent years, there has been a strong demand for lighter and stronger car bodies for automobiles, and for this reason, attempts have been made to use FRP (glass fiber reinforced plastic) for various parts. To manufacture these FRP parts, a method generally adopted is to use a molding material called a prepreg sheet, which is made by impregnating glass fiber or the like with a thermosetting resin and forming it into a sheet shape, and hot press molding the material. This is done by first setting a laminate of prepreg sheets cut to an appropriate length according to the product on a lower mold, and then pressing it while heating it with an upper mold and a lower mold. The resin content in the sheet is once softened, thereby integrating the above-mentioned laminated materials to obtain a product with a desired shape.

On the other hand, in order to improve product strength, long glass fibers (continuous glass fibers) are sometimes blended into prepreg sheets, but this type of prepreg sheet can be used to produce FRP parts with uneven parts, such as engine mount members. When manufacturing, the following problems arise according to the conventional method as described above. That is, as shown in FIG. 9, the upper die A and the lower die B for molding have concave portions A1. A2 and the convex portions B+ and Bz are formed, but the sheet C...C is still softened near the convex portions B+ and 82 when the prepreg sheet 1-C...C is set on the lower mold B. Because it is not in close contact with the lower mold B, the sheet C.
...Gap a1 between C and lower mold B. A2 occurs. Therefore, when the molds are matched in this state, both ends of the prepreg sheets C...C form the uneven portions A+ and A2 in the upper mold A and the lower mold B.

B+, B2, and the gap a1
．． Since it is pressed along the lower mold B so that a2 disappears, tension is applied to the sheet C...C or the long glass fibers in the sheet C...C in the longitudinal direction of the product (in the left-right direction in the drawing). It will work. With the long glass fibers being stretched in this way, the resin in the prepreg seams 1-C...C gradually softens and becomes fluid by heating and pressurizing both molds A and B. Then, the resin's restraint on the long glass fibers is released, and the long fibers move through the shortest distance in the longitudinal direction of the product due to their own contraction force, and as a result, as shown in FIG. Near the top of the convex portion 81 (82) of mold B, the long glass fibers are gathered toward the lower mold B side, resulting in a resin-rich portion E where no long fibers are present in the upper part in the thickness direction of the product.
will occur. If such a resin-rich portion E is present in the product, the strength of that portion will be weakened and cracks will occur, or in the worst case, the product will be damaged.

In addition, as described later, in one embodiment of the method of the present invention,
Prior to molding, a prepreg sheet cut in advance to fit the mold surface in the recessed part of the mold is pasted to the mold surface. 56-14
There is a method published in Publication No. 4923. but,
The method disclosed in the publication is a method in which prepreg sheets cut to match the irregularities of a male mold are laminated to form a recess of a predetermined size and depth, and the recesses are pressed by the male mold to integrate them. Since the prepreg sheet is not deformed to fit the mold, it does not prevent the maldistribution of the composition, that is, the generation of resin-rich areas, which occurs during press molding of the prepreg sheet as described above. Therefore, the purpose of the present invention is are completely different.

(Purpose of the Invention) The present invention addresses the above-mentioned problems during press processing of prepreg sheets containing long glass fibers, and uses this type of prepreg sheet to produce FRP parts having uneven parts. When molding, the purpose is to prevent the occurrence of resin-rich portions caused by uneven distribution of long glass fibers in the uneven portions, thereby improving the strength of the product.

(Creation of the Invention) In order to achieve the above object, the method for manufacturing FRP parts according to the present invention is characterized by having the following configuration.

That is, in a method of hot press molding parts having uneven parts using a laminated material of prepreg sheets containing long fibers, a fiber material is applied in advance to the local surface of the molding die corresponding to the uneven parts. Thereafter, the prepreg sheet is loaded into the mold and hot pressed to combine the sheet and the fibrous material into a composite body. The above-mentioned method of applying the fiber material includes, for example, spraying short glass fibers together with a binder (synthetic resin), or applying a pre-preg sheet cut in advance to fit the uneven portions of the mold. A method of attaching the fibers to a surface, or an electrostatic flocking method in which a mold is electrically charged and glass fibers are sprayed onto the uneven mold surface to electrically adhere the fibers is employed.

According to such a configuration, even if a portion where the long fibers are absent or few are present near the tops of the uneven portions due to uneven distribution of the long glass fibers in the prepreg sheet during pressing,
Is that part made into a mold in advance? Il! ! Since it is integrated with the applied fiber material, there will be sufficient fibers in this area as well. This prevents the occurrence of resin-rich portions near the tops of the uneven portions, making it possible to obtain a product with uniform composition and therefore uniform strength.

(Example) Examples of the present invention will be described below.

This embodiment has convex portions X on both ends as shown in FIG. ,
X2 and reinforcing rib part in the center ×3...×3
This relates to the case of manufacturing a product (engine mount member) X having the following:
As shown in FIG. 2, it is composed of an upper mold 1 and a lower mold 2, and the upper cough mold 1 and the lower mold 2 have four parts 1a for forming the convex portions X+ and X2.

1b and convex portions 2a and 2b are formed, respectively.

Further, although not shown, the upper mold 1 and the lower mold 2 are provided with an uneven portion for forming the rib portion x3 of the product X. Then, the above product
In this case, the prepreg sheet 3, which is made by impregnating glass fibers containing long fibers with a thermosetting resin and forming them into a sheet shape, is cut into appropriate lengths depending on the product. Set the upper part onto the lower mold 2. The sheets 3...3 may be set on the lower mold 2 either before or after, but prior to press molding, the recesses 1a, 1b (for forming the rib portions x 3) in the upper mold 1 are prepared. Short glass fibers 4...4 are applied to the local surfaces of (including the concave portions). As shown in FIG. 3, these short glass fibers 4...4 are obtained by cutting continuous glass fibers 5 in a lobe shape into short lengths using a cutter 6, and are sprayed onto the local parts of the concave portions 1a (ill) by spraying 7. Along with spraying on the surface,
A binder 8 made of synthetic resin is sprayed from the tip of the spray 7 and is applied to the local surface.

However, the recess 1a of the upper die 1 is formed as described above.

After covering short glass fibers 4...4 on 1b and setting the prepreg sheets 3...3 on the lower mold 2, the upper mold 1
is moved downward, and the sheets 3 . . . 3 are hot-pressed while being heated by the upper mold 1 and the lower mold.

As a result, the synthetic resin constituting the prepreg sheets 3...3 and the synthetic resin (binder 8) for bonding the short glass fibers 4...4 are softened and integrated by the heat and pressure associated with pressing. As a result, the space within the mold is filled with the synthetic resins 6 and 8, as shown in FIG. At this time, the long glass fibers 9 contained in the prepreg sheet 3...
...Since tension is applied to 9 during mold clamping, the synthetic resin 6
When the resin 6 softens and is released from the restraint by the resin 6, the convex portion 2 of the lower mold 2 tries to pass the shortest distance in the longitudinal direction of the product.
Near the top of a (2b), the glass fibers 9...9 moved toward the lower mold 2 in the thickness direction, and as a result, the long glass fibers 9...9 gathered toward the protrusion 2a (:in) of the lower mold 2. state. However, since the above-mentioned short glass fibers 4 . . . 4 have been applied in advance above the vicinity of the top of the convex portion 2a (2b), that is, on the local surface of the concave portion 1a (1b) in the upper die 1, the above-mentioned Even if the long glass fibers 9...9 are gathered on the convex portion 2a (2b) side of the lower die 2, the short glass fibers 4...4 are densely present above the convex portion 2a (2b) side. I will do it. As a result, the convex portion X1 of the product X. This prevents the occurrence of resin-rich portions where glass fibers are not present at X2 and rib portions x3-X3, making it possible to obtain a product with uniform composition and therefore uniform strength.

Note that in the above embodiment, the recess 1a in the upper mold 1
The short glass fibers 4...4 were sprayed together with a binder 8 using a spray 7 to adhere to the local surface of the fibers 1b, and as shown in FIG. The prepreg sheet 3' may be pasted on the surface of the recess 1a', in which case the sheet 3'
' may include not only glass fibers [4'...4' as shown in the figure, but also long glass fibers. Further, as shown in FIG. 6, short glass fibers 4''...4'' cut into short lengths in the same manner as in the first embodiment are placed on the surface of the recess 1a'' after the mold 1'' is charged.
It may be electrically deposited by spraying with an air spray 7''.

Next, an experiment conducted to confirm the effects of the present invention will be briefly described.

As shown in Fig. 7, with both ends of product X (engine mount member) fixed, a load P is applied from above to one convex portion x1 of product was measured.

As a result, as shown in the graph of FIG. 8, the product X according to the present invention has a lower displacement m for the same load than the product In other words, the rigidity was significantly increased, and the maximum load that could be applied was also increased by approximately 70 to 801 f'5, confirming that the strength was significantly improved. Furthermore, the products x, x' used in this experiment
Both contain 50 W (%) of long glass fibers and 10 W (%) of short glass fibers.

(Effects of the Invention) As described above, according to the present invention, when a prepreg sheet containing long glass fibers is used to mold a part having uneven parts, resin-rich parts that tend to occur in the uneven parts can be reduced. Its occurrence is prevented.

As a result, the strength of the product is improved, cracks, etc. in the resin-rich portion are prevented, and a product with uniform strength can be obtained.

[Brief explanation of the drawing]

FIG. 7 is a perspective view showing an example of a product manufactured by the method of the present invention, FIGS. 2 to 4 show the first embodiment of the method of the present invention, and FIG. A schematic cross-sectional view showing the prepreg sheet set on the lower mold of J5,
Fig. 3 is a schematic explanatory diagram showing a method for attaching short glass fibers to the surface of the concave portion of the upper mold, Fig. 4 is an enlarged sectional view showing the vicinity of the convex portion of the lower mold during heat pressing, and Fig. 5 is the second A schematic cross-sectional view showing a state in which a prepreg sheet is attached to the surface of a recessed part of a mold in an example, FIG. 6 is a schematic explanatory view showing a method of adhering short glass fibers in a third example, and FIG. 7 shows a diagram of product strength. An explanatory diagram of the experiment conducted to confirm the
Fig. 8 is a graph showing the product strength characteristics obtained through the experiment in comparison with the conventional example, and Fig. 9 is a graph showing the characteristics of the product strength obtained in the experiment, and Fig. 9 is the graph of the conventional FRP.
FIG. 10 is a schematic sectional view used to explain the method of manufacturing the parts, and is an enlarged sectional view of the main part used to explain the problem.

Claims (1)

[Claims] (1) A method of hot press molding parts having uneven parts using a prepreg sheet containing long fibers, in which a fiber material is applied in advance to the local surface of a molding die corresponding to the uneven parts. A method for producing an FRP component, which comprises: thereafter, loading a prepreg sheet into the mold and performing hot press molding to integrate the sheet and the fibrous material into a composite body.