JPH0375105A - Production of preform for fiber reinforced plastic - Google Patents

Abstract

PURPOSE:To prevent collapse of a preform and to obtain a sound preform having thickness preset by design by performing application of a binder to both surface 2 of the preform together with suction of air. CONSTITUTION:When an unsolidified preform 3 is on the rear surface of a top force 2, a binder is applied while continuing suction of air to a suction chamber a the unsolidified preform is impregnated with the binder from the rear surface. A cavity slepe bottom force 6 having a suction port 10 is approached the rear surface the rear surface. A valve provided to a suction port 8 is closed just before the bottom force 6 is closely stuck to the preform 3. Suction due to a suction chamber 1 is instantly stopped. Immediately mold clamping is performed by the top force 2 and the bottom force 6 and the gap between the top force and the bottom force is sealed by a sealer 7. Then the air is sucked through the suction port 10 provided to one place of the bottom force 6 by an exhauster. The top force 2 is separated from the preform 3. Then the binder 5 is applied to the upper face of the preform 3 while sucking air. The binder 5 is penetrated toward the inside from the upper face of the preform 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a preform used for manufacturing a fiber-reinforced plastic guard-shaped body, and more particularly to a method for manufacturing a preform body that is easy to handle.

[Conventional technology]

BACKGROUND ART Conventionally, injection molding methods, sheet molding compound methods (SMC methods), and the like have been generally used to manufacture fiber-reinforced plastic molded bodies. In general, the injection molding method is suitable for small molded products, and the SMC method is suitable for large molded products.

Incidentally, recently it has been proposed to form parts such as the outer panels of automobiles from fiber-reinforced plastic rectangular bodies. However, when it was attempted to form these parts using fiber-reinforced plastic molded bodies, it was found that it was difficult to do so using conventional methods, as they were not only extremely large but also had complex shapes.

Therefore, the present applicant has applied for a patent on a method of creating a preform by first adsorbing resin powder and reinforcing chopped fibers into a preform mold, then scattering a binder on top of the adsorbed resin powder, and then drying it. I did it (Special request 1976)
3-143682). In this method, the preform mold is placed in a suction chamber equipped with an exhaust fan, the preform mold is inserted into a tank into which chopped fibers and resin powder have been charged, and the exhaust fan is activated. , the chopped fibers and resin powder in the tank are stirred up and adsorbed to the preform mold to form an unsolidified preform.

According to this method, preforms with complicated shapes can be manufactured in a short time, and the thickness of the obtained preforms is also uniform.

However, since the preform is not hardened, more binder needs to be applied. In that case, the binder was sprayed from below while the preform was adsorbed to the preform mold, and then the mold was released, and finally the preform was dried and solidified to complete the preform.

[Problem to be solved by the invention]

In the case of the above method, the binder is impregnated from the bottom surface of the preform to the vicinity of the center of the preform in a state before mold release, but when a particularly thick preform is formed, the binder is not always sufficiently impregnated to the top surface. Furthermore, when attempting to form a preform with a complicated shape, it becomes difficult to maintain the shape due to collapse of the vertical walls. Therefore, it has been difficult to obtain a sound preform having the thickness as designed.

Therefore, the object of the present invention is to prevent collapse during mold release.
An object of the present invention is to provide a method for manufacturing a preform having a designed thickness.

[Means to solve the problem]

As a result of intensive research in view of the above problems, the present inventor applied a binder to both the front and back surfaces of the unsolidified preform,
Furthermore, they discovered that by carefully controlling the timing of mold clamping and mold release, it is possible to prevent the preform from collapsing, thereby completing the present invention.

That is, the method of the present invention for manufacturing a preform for fiber-reinforced plastic by mixing fibers and resin and impregnating them with a binder and then releasing the mold includes: (a) a mesh-like upper surface installed on the lower surface of a suction chamber; By applying a binder to the lower surface of the unsolidified preform made of a mixture of resin and fibers adsorbed to the lower surface of the mold while continuing to suck air by the suction chamber, the binder is applied from the lower surface of the unsolidified preform. (b) bringing a lower mold close to the lower surface of the unsolidified preform, stopping suction by the suction chamber just before the unsolidified preform and the lower mold come into close contact, and then clamping the mold; (C) closing the gap between the upper mold and the lower mold with a seal and sucking air from the lower mold; (d) releasing the upper mold while sucking air; (e) By applying a binder to the upper surface of the unsolidified preform while sucking air from the lower mold,
The present invention is characterized by comprising a step of impregnating the binder from the upper surface of the unsolidified preform.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows the first step. 1 is a hollow suction chamber having a substantially conical shape, and an exhaust fan (not shown) is connected to the upper part of the suction chamber. Reference numeral 2 denotes a mesh-like upper mold for molding a preform, which is installed on the lower surface of the suction chamber 1. The chopped fibers and resin powder supplied from below are adsorbed to a certain thickness on the lower surface of the upper mold 2 by suctioning the air in the suction chamber, and are formed into an unsolidified preform 3 containing a mixture of fibers and resin. It becomes.

When the unsolidified preform 3 is adsorbed to the lower surface of the upper die 2 in this manner, the binder 5 is applied while continuing to suck air using the suction chamber, so that the binder is impregnated from the lower surface of the unsolidified preform. That is, by suctioning, the unsolidified preform 3 is prevented from falling from the upper mold 2, and impregnation with the binder is promoted.

Next, as a second step, as shown in FIG. 2, a mesh having a shape corresponding to the preform is provided on the upper surface of the unsolidified preform 3, and the side and lower surfaces are made of plate walls.
A hollow lower mold 6 having an inlet 10 is brought close to the lower surface,
Immediately before the preform 3 and the lower mold 6 come into close contact, a valve (not shown) attached to the suction port 8 is closed, and the suction chamber 1 is closed.
Instantly stops suction. Then, as shown in FIG. 3, the molds are immediately clamped by the upper mold 2 and the lower mold 6. The time to stop suction is when the distance to preform 3 is 150 mm.
It is desirable to reach the point when the temperature reaches about an.

Further, when the mold is clamped, the upper surface of the lower mold 6 may get caught in slight irregularities on the surface of the preform, and the preform may be scraped off. Therefore, the lower mold suction surface has a clearance equal to the thickness of the preform with respect to the upper mold suction surface, and only the vertical wall 6a (Fig. 2) of the lower mold 6 is made larger so that there is a gap between the lower mold suction surface and the preform. It is preferable to provide a slight gap.

Next, as a third step, as shown in FIG. 4, the gap between the upper mold and the lower mold is closed with a seal 7. This is to prevent air from being drawn in from the gap between the upper and lower molds and damaging the edges of the preform.

Furthermore, the valve of the leak hole 9 provided in the wall of the suction chamber is opened to allow an appropriate amount of air to flow in.

Next, suction of air is started from a hole lO provided at one location in the lower mold 6 using an exhaust fan (not shown). After applying strong suction for 30 seconds, in the fourth step, the suction force is weakened to separate the upper mold 2 from the preform 3 as shown in FIG.

The position where the suction port 1O of the lower mold 6 is provided is not limited to the bottom surface, but may be placed on the side surface. In any case, the suction port IO is provided at a position where the most effective suction state can be obtained.

Next, as a fifth step, as shown in FIG. 6, the binder 5 is applied to the upper surface of the preform 3 while sucking air. The binder permeates into the preform 3 from the upper surface thereof. Therefore, at this point, the entire preform 3 is evenly impregnated with the binder.

Finally, the preform 3 is dried and solidified.

〔Example〕

The present invention will be explained in more detail by the following specific examples.

Example 1 A 35# 6-nylon powder was prepared as a resin powder, and a carbon fiber with an average length of 25 mm, a width of 2.5 m, and a thickness of 0.1 ms was used as a chopped fiber. Both were mixed at a ratio of 40% and used as a raw material for a preform.

As shown in Figure 1, a #60
An upper mold having a 5US mesh wall was attached, and the above raw material was adsorbed to the lower surface of the upper mold to a thickness of 7M by a suction method. While continuing suction, a 5% solution of alcohol-soluble nylon (Toshi-IIA-70) in methanol was sprayed onto the preform from below as a binder.

Similar to the upper mold, the lower mold made by attaching the upper wall with the shape corresponding to the preform made of #60SUS mesh to the wooden frame was brought close, and when the distance reached 150 m, the suction by the chamber was started. It stopped and the mold was closed.

Seal the opening between the upper and lower molds with silicone rubber, etc.
A leak valve previously installed on the wall of the suction chamber was opened.

After suction was applied from below for 30 seconds as shown in FIG. 4, the suction force was weakened and the upper mold was separated as shown in FIG.

After increasing the suction power again, the preform was sprayed with the same binder as above.

Finally, after drying and solidifying the preform, it was released from the lower mold. In the above process, the upper and lower molds were released smoothly, and the preform surface did not collapse at all.

〔Effect of the invention〕

As explained above, according to the method of the present invention, since the binder is applied to both the front and back surfaces of the preform while air is sucked, the preform is prevented from collapsing, and the preform is kept in a sound state with the designed thickness. A preform can be obtained.

[Brief explanation of drawings]

1, 2, 3, 4, 5, and 6 are sectional views showing the method of the present invention in the order of steps.・Suction chamber ・Upper mold ・Preform ・Binder ・Lower mold Figure 1 Figure 2

Claims (1)

[Claims] (1) In a method for manufacturing a preform for fiber reinforced plastics, (a) on the lower surface of an unsolidified preform made of a mixture of resin and fibers adsorbed to the lower surface of a mesh-like upper mold installed on the lower surface of a suction chamber; impregnating the binder from the lower surface of the unsolidified preform by applying the binder while continuing suction of air by the suction chamber; (b) bringing a lower mold close to the lower surface of the unsolidified preform; Immediately before the unsolidified preform and the lower mold come into close contact, the suction by the suction chamber is stopped, and then the mold is clamped; (c) the gap between the upper mold and the lower mold is closed with a seal; (d) releasing the upper mold while sucking air; and (e) applying a binder to the upper surface of the unsolidified preform while sucking air from the lower mold. ,
A method for producing a preform for fiber-reinforced plastics, comprising the step of impregnating the binder from the upper surface of the unsolidified preform.