JPH0643077B2 - Molding method for fiber-reinforced resin moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention inserts a fiber cloth, a mat or the like into a cavity of a mold, and injects a resin into the cavity under pressure to form a fiber-reinforced resin molded product. It is about the method.

[Prior Art] Generally, in this type of molding method, a cloth or mat made of glass fiber, organic fiber, inorganic fiber, etc. is inserted along one of the pair of mating molds, and the mold is closed. After the mold is clamped, the cavity is depressurized and the resin is injected under pressure while maintaining that state. The resin used for this molding is an uncured thermosetting resin liquid such as polyester resin, polyurethane resin, epoxy resin, epoxy acrylate resin, unsaturated acrylate resin, which is pre-blended with a curing agent. It becomes a resin molded product.

[Problems to be Solved by the Invention] In the above conventional method, the resin is permeated between the fibers and defoamed by the suction force in the cavity due to the pressure and the pressure reduction. Since the resin is difficult to flow, the resin injected into the cavity flows in a space with low flow resistance such as between the fiber cloth etc. and the cavity wall or the gap of the laminated fiber cloth etc., and after filling those spaces. Infiltrate into fiber cloth, etc.

For this reason, even if the gate position and the decompression position are set to the cavity so that the resin flows in one direction while permeating between the fibers, the permeation of the resin after filling the space occurs from the periphery of the fiber cloth or the like. In addition, the air between the fibers, which was previously closed by the resin, has no place to flow out elsewhere, and this acts as a resistance that impedes the resin permeation due to pressure injection, resulting in impregnation unevenness and bubble formation. It causes the occurrence.

As a means for solving such a problem, an invention in which a resin is pressure-injected into each cavity in each section and the resin is uniformly impregnated between fibers by a pressing force and a capillary phenomenon (Japanese Patent Application No. 63-64945, Japanese Patent Application No. 63-71001, Japanese Patent Application No. 6
3-71002). However, in this invention, it took a long time to impregnate the fibers.

Therefore, the present inventor has further conducted various researches on the permeation of the resin between the fibers, and as a result, controls the difference in the flow resistance between the portion where the insert material is present and the portion where there is a gap to be small in the resin injection process. However, it was found to be more effective than the case according to the previous invention.

Therefore, an object of the present invention is to provide a new molding method capable of reducing the difference in flow resistance by an extremely simple means, thereby preventing the occurrence of impregnation unevenness and bubbles without requiring a long molding time. is there.

[Means for Solving the Problems] One of the inventions according to the above object is to insert an insert material such as a fiber cloth or a mat into a cavity of a mold,
When molding a fiber-reinforced resin molded product by injecting resin into the cavity from a gate under pressure, a gas supply / discharge port is provided in the wall part of the mold where the resin flow front end reaches, and the cavity is supplied from the supply / discharge port. After pressure-filling with gas, the resin is injected under pressure, and the gas in the cavity is discharged while correlating it with the amount of resin injected. It is a method for molding a fiber-reinforced resin molded product that is controlled every time a resin is pressurized by pressure.

According to another aspect of the present invention, an insert material such as a fiber cloth and a mat is inserted into a cavity of a mold, and a resin is pressure-injected from the gate into the cavity to form a fiber-reinforced resin molded product. The resin is injected under pressure and the gas is supplied to and discharged from the resin-uninjected portion alternately, and the position difference of the resin flow tip caused by the difference in flow resistance is caused by the gas pressure for each injection of resin. It is a method of controlling a fiber-reinforced resin molded product to be controlled.

Still another aspect of the present invention is to insert a fiber cloth, a mat or the like insert material into a cavity of a mold, and inject resin into the cavity under pressure from a gate to mold a fiber-reinforced resin molded product. A method for molding a fiber-reinforced resin molded product, in which a portion of the mold having a small flow resistance to the resin flow is cooled to increase the viscosity of the resin flow in that part to control the positional difference of the resin flow tip caused by the difference in the flow resistance. is there.

[Example] In the figure, reference numeral 1 denotes a long insert material, which is formed by flatly forming a glass fiber cloth 3 around a core material 2 of a thin metal plate in multiple layers as shown in FIG.

Reference numeral 4 denotes a mold, which is composed of a pair of matching molds, and one mold wall of the cavity 5 is provided with a resin injection gate 8 connected to a pipe line 7 having an injection valve 6.

Further, a gas supply / discharge port 12 is provided on the wall portion of the mold 4 where the resin flow front end reaches, to which a pipe line 11 having an air supply valve 9 and an exhaust valve 10 is connected.

The insert material 1 in the cavity 5 is fixed by a generally-used means so as not to move by the injection pressure.

After molding is performed by closing the mold and closing the mold, an uncured thermosetting resin liquid such as a polyester resin mixed with a curing agent is pressed into the cavity 5 from the gate 8 with a fixed amount by a valve operation. Injected.

In the mold 4, when the air supply valve 9 is closed and the exhaust port valve 10 is opened to inject the resin under pressure from the gate 8 into the cavity 5, the injected resin 13 partially fills the cavity around the gate. When the injection valve 6 is closed in this state and the pressure injection is temporarily stopped, the resin enters the insert material 1 and permeates between the fibers due to the capillary phenomenon, and also flows into the gap around the cavity. These two flows are faster on the side of the cavity where the flow resistance is small, and as shown in FIG. 3, there is a difference in the tip position 13a of the resin flow.

When the pressure injection of the resin is intermittently performed under such a state, the resin flows into the cavity end while impregnating the insert material 1, but at the cavity end, the preceding resin flow field is generated. Since there is no resin, the insert material is 1
It will penetrate into the inside of. Therefore, as shown in FIG. 5, the unimpregnated portion 1a of the insert material 1 is impregnated with the resin from the surroundings, and the air in that portion does not escape and remains in the insert material. This internal air sometimes obstructs the complete pressure injection of resin, and also causes the generation of bubbles after resin impregnation.

Therefore, air pressure is used to avoid such a phenomenon. First, the cavity internal pressure is maintained at a predetermined pressure before the resin is injected under pressure. This operation is performed by closing the exhaust valve 10 and opening the air supply valve 9 to pressurize and fill the cavity 5 with air from the air supply / exhaust port 12, and when the inside of the cavity reaches a predetermined pressure, the air supply valve 9 is closed. It can be done easily.

After such preparation is completed, a fixed amount of resin is injected under pressure. The flow of the resin in the injected cavity is suppressed within a certain range by the air pressure.

However, since the resin that has entered the insert material 1 is impregnated between the fibers due to the capillary phenomenon, the resin impregnation proceeds even if the resin flow is suppressed, and the amount of resin around the insert material decreases accordingly. As a result, the difference in the tip end position 13a of the resin flow becomes small as shown in FIG. 4, regardless of the magnitude of the flow resistance.

In addition, the resin injection increases the cavity pressure, making it difficult to continue the resin injection.
The exhaust valve 10 is opened to discharge the air amount corresponding to the injection amount, and the cavity internal pressure is reduced. This makes it possible to inject a new fixed amount of resin under pressure.

If such an operation, that is, the injection of the resin and the decrease of the internal pressure of the cavity are performed alternately and in correlation, the difference in the tip position 13a of the resin flow for each injection becomes small, and the air in the insert material is also exhausted at each depressurization. As a result, the impregnation of the resin becomes uniform, and a fiber-reinforced resin molded product without bubbles remaining can be obtained.

Further, in order to suppress the resin flow with air pressure, pressure injection of resin is preceded and air supply / discharge from the supply / discharge port 12 is repeated in a short time. The air supply and exhaust can be performed by alternately operating the two valves 9 and 10.

By the pressure filling of the air from the supply / discharge port 12, the tip of the resin flow is pressed. If this compression is repeated for a short time, the tip of the resin flow will be as if it was just hit with a hammer, and the resin flow around the insert material with low flow resistance will be suppressed more than the resin flow inside the insert material. At the same time, it will be driven into the insert material. As a result, the resin flow recedes around the insert material, and the flow difference with the resin flow in the insert material becomes extremely small.

In this manner, when the position difference of the flow front is corrected and the pressure injection is performed every time the resin is injected under pressure, a fiber-reinforced resin molded product without bubbles can be obtained.

The example shown in FIG. 6 is a case where the flow resistance is made uniform by cooling.

In order to cool a portion of the insert material around which the resin easily flows, a flow passage 14 is provided in the mold along the cavity 5, and a cooling medium is supplied to the flow passage 14 to cool the periphery of the cavity to a required temperature.

The flow path 14 can be provided by using any means depending on the shape of the cavity. However, as shown in the figure, when the cavity peripheral wall is a curved surface, a groove provided on one of the patenting surfaces of the mold 4 is used. It can be the flow path 14.
Ports 15 and 16 for the cooling medium are formed at both ends of the groove, and an annular ring 17 for sealing is fitted around the inside of the groove so that the other side of the mold 4 can be accommodated as shown in FIG. Then, the mold is closed and the cooling medium is supplied to the flow path 14.

By supplying the cooling medium, the temperature around the cavity is lower than that of the insert portion, the resin flowing around the insert material is cooled, the viscosity is increased, and the fluidity is lowered. For this reason, the resin flow around the insert material is slowed down, and there is no great difference from the resin flow inside the insert material. As a result, the resin is not impregnated in advance from the periphery,
The resin is impregnated from one side of the insert material to the other without taking in air.

The air in the cavity is discharged by a predetermined amount each time the resin is injected under pressure by opening the exhaust valve 10. When the molded product is taken out after the completion of molding, the cooling medium in the flow path is blown with air before opening the mold. Discharge by.

When cooling is performed with a plurality of flow passages 14 as shown in the figure, the temperature of the flow passages 14 can be individually adjusted,
This makes it possible to perform finer flow control.

Furthermore, when cooling reaches the resin in the insert material, the insert portion of the mold may be heated by a heater or the like.

[Advantages of the Invention] As described above, the present invention controls the velocity of the preceding resin flow in the cavity by utilizing the means such as gas pressure and cooling, and the difference between the tip positions of the resin flow inside and outside the insert material. Since the amount is minimized, the impregnation of the resin around the insert material does not occur in advance.

Therefore, resin impregnation occurs in sequence from one side to the other while extruding the air in the insert material, and the position of the flow front is also aligned, so that a long molded product with no impregnation unevenness or bubbles can be molded in a relatively short time. There is an advantage that can be.

[Brief description of drawings]

The drawings show an embodiment of a method for molding a fiber-reinforced resin molded product according to the present invention. FIG. 1 is a schematic cross-sectional plan view of a mold,
FIG. 2 is a schematic sectional view thereof, FIGS. 3 to 5 are explanatory views of a molding state, and FIG. 6 is a schematic plan view of a mold used as an example of another method when the mold is opened. FIG. 7 is a schematic sectional view thereof. 1 ... Insert material, 2 ... Core material, 3 ... Fiber cloth, 4 ... Mold, 5 ... Cavity, 6 ... Injection valve, 8 ... Gate, 9 ... Air supply valve, 10 ... Exhaust valve, 12 ...... Supply / exhaust port 13 ... Resin flow, 13a ... Flow front end 14 ... Flow path

Claims (3)

[Claims] 1. A resin flow of the mold, wherein an insert material such as a fiber cloth or a mat is inserted into a mold cavity, and a resin is injected into the cavity under pressure from a gate to mold a fiber-reinforced resin molded product. A gas supply / exhaust port is provided on the wall where the tip reaches, and the cavity is pressure-filled from the supply / exhaust port, and then the resin is pressurized and injected, and the gas in the cavity is adjusted to the resin injection amount. A method for molding a fiber-reinforced resin molded article, which comprises discharging the resin while correlating it and controlling a positional difference of a resin flow front end caused by a difference in flow resistance for each pressure injection of the resin by a gas pressure. 2. An insert material such as a fiber cloth or mat is inserted into a cavity of a mold, and resin is injected under pressure from the gate into the cavity to form a fiber-reinforced resin molded product. By alternately repeating pressure injection and gas supply to and discharge from the resin-uninjected portion, it is possible to control the position difference of the resin flow front end caused by the difference in flow resistance for each pressure injection of resin by gas pressure. A method for molding a fiber-reinforced resin molded product characterized. 3. A resin flow in a mold for molding a fiber reinforced resin molded product by inserting an insert material such as a fiber cloth or a mat into a cavity of the mold and injecting resin into the cavity under pressure from a gate. A method for molding a fiber-reinforced resin molded article, which comprises cooling a portion having a small flow resistance to the resin, increasing the viscosity of the resin flow in the portion, and controlling the positional difference of the resin flow front end caused by the difference in the flow resistance.