JPH05329856A - Manufacture and device of hollow fiber-reinforced resin molded product - Google Patents

Abstract

PURPOSE:To provide a method and device suitable for internal pressure molding of a cylindrical hollow product of fiber-reinforced resin into a complicated external form. CONSTITUTION:A fluororubber tube 5 coated with a molding material of fiber-reinforced resin is put within a predetermined mold and nitrogen gas is injected within the fluororubber tube, through which the fluororubber tube is expanded and the molding material is pressed against the inside of the mold. Since the inside of the mold is decompressed to a predetermined degree of vacuum prior to injection of the nitrogen gas, at the time of application of inner pressure to the inside of the mold, the molding material is stretched smooth according to expansion of the fluororubber tube, a molded product having a uniform thickness is obtained even if the same is in a complicated form. Then at the time of also inner pressure molding, since internal vacuum evacuation of the mold is performed on the outside of the molding material, the molding material is stuck favorably to the inside of the mold and a molded product having high dimesional accuracy on an external form is obtained. A joining between the fluororubber tube and a nitrogen gas injection nozzle 8 is performed through a joint member 6 by the quality of the material having the high coefficient of expansion and favorable gaseous sealing condition is given to a space between both of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a hollow fiber-reinforced resin molded article, and more particularly to a method and an apparatus for producing a hollow fiber-reinforced resin molded article by an improved internal pressure molding method.

[0002]

Fiber reinforced synthetic resin (FRP) is a matrix material of thermosetting resin such as epoxy or polyester, or thermoplastic resin such as polyethylene, polypropylene, polyamide, PPS, PEEK, glass fiber or carbon fiber. , Which is made of reinforced fibers such as aramid fiber, and is lightweight and has excellent strength properties, from aerospace industry to construction, familiar products such as sports equipment,
It is used in a wide range of fields.

Centrifugal molding, pultrusion molding, filament winding molding, and the like are known as methods for molding FRP into a tubular or hollow body.

In the centrifugal molding method, the inner surface of a rotating cylinder is
This is a method in which fibers are wound from rollers concentrically arranged in this cylinder, and the fibers are sprayed and impregnated with a resin for matrix, and then solidified or cured, but the diameter is relatively large and the shape is simple. However, there is a defect that only the product of No. 1 can be manufactured and the manufacturing cost becomes high due to the large scale of the device.

The pultrusion molding method is a method in which a reinforcing fiber base material is impregnated with a resin, and then the resin is drawn out using a mold to solidify or cure the resin to obtain a molded product. Only straight pipes can be manufactured, and there are drawbacks such as increased equipment costs.

The filament winding molding method is a method in which a resin-impregnated fiber is wound around a mandrel, and the mandrel is pulled out after the resin is solidified or cured.
Since the ratio of long fibers can be increased, a hollow body having a relatively high strength can be obtained. However, there are drawbacks such that only axially symmetric products can be manufactured, and the equipment cost increases.

Further, in these molding methods, it is assumed that a thermosetting resin is used as a matrix, and it is difficult to apply it when the matrix is a thermoplastic resin.

Under these circumstances, it is applicable whether the matrix resin is thermosetting or thermoplastic, and as a method for easily molding a pipe-shaped fiber-reinforced resin product, an internal pressure molding is used. A method called the law was developed.

The internal pressure molding method is a method in which a cylindrical molding material is arranged in a mold cavity, and pressure is applied from the inside of the cylinder to heat and solidify or cure the material in a state of closely contacting with the mold. Yes, it is classified into the following methods depending on the means for applying internal pressure. (A) Wrap a cylindrical molding material around a core made of a material that has excellent heat resistance and a high coefficient of thermal expansion, such as synthetic rubber or tetrafluoride resin, and place it in the mold cavity. A method of molding by pressing the molding material against the inner surface of the mold with the pressure of expansion. (A) A bag formed of a flexible and highly heat-resistant material such as nylon or silicone rubber is wrapped around a tubular molding material, or a molding material preformed using a core metal is used. A method in which this bag arranged in the center is placed in a mold cavity, a pressurized fluid such as compressed air is sent into the bag to expand the bag, and the molding material is pressed against the inner surface of the mold to mold the material.

[0010]

However, in the conventional internal pressure molding method, the pressure applied to the molding material depends on the thermal expansion of the core material and the expansion of the bag by the pressurized fluid, and the pressure is locally applied. Can't adjust. For this reason, it is preferable to mold into a simple pipe shape, but when molding a hollow product with a complicated shape, the pressing force received by the molding material becomes uneven in each part, and a molded product with a uniform wall thickness is obtained. It had a problem that it could not.

Further, the core or bag may locally expand excessively depending on the complicated shape of the molded product to be obtained, and the core or bag may be damaged or burst at this portion.

[0012]

Therefore, the present invention is a method for producing a hollow fiber-reinforced resin molded product which is an improvement over the conventional internal pressure molding method and can mold even a complicated shape without inconvenience. It is an object of the present invention to provide a device.

The method of the present invention for achieving this object comprises:
A molding material made of fiber reinforced resin is placed around a cylinder made of a material with good flexibility and excellent heat resistance, and the molding material is pressed against the inner surface of the mold by applying internal pressure to the cylinder and expanding it. Then, in the method for producing a hollow fiber reinforced resin molded product by solidifying or hardening, the cavity is depressurized to a predetermined vacuum degree, and then the cylinder is pressurized.

Preferably, the cavity in the mold is evacuated from the outside of the molding material while the cylinder is being pressurized.

The hollow fiber reinforced resin molded article manufacturing apparatus according to the present invention comprises an openable and closable mold configured to provide a cavity corresponding to the outer shape of the hollow fiber reinforced resin molded article to be molded when the mold is closed. , A process for injecting a pressurizing fluid from at least one open end of a cylindrical body made of a material having good flexibility and excellent heat resistance with a molding material externally applied to expand the cylindrical body by internal pressure. It is characterized by comprising a pressure means and a decompression means for decompressing the inside of the cavity before the cylinder body is expanded by the pressure means by the internal pressure.

In a preferred embodiment of the apparatus of the present invention, the depressurizing means operates so as to evacuate the cavity from the outside of the forming material even during the internal pressure forming by expanding the cylindrical body by the pressurizing means. To be done.

The depressurizing means is provided with a groove that is recessed in the parting surface of one or both of the mold members so as to extend for communication over substantially the entire length of the cavity, and the groove that communicates with this groove and is outside the mold member. It can be configured to include an exhaust passage opened to the side surface and a vacuum pump connected to the opening of the exhaust passage.

Preferably, a joint member having a through hole into which the open end of the cylinder is inserted from the inside is arranged in the mold, and a pressurized fluid injection nozzle serving as a pressurizing means is inserted from outside the through hole. The joint member, which is connected to the open end of the cylindrical body, is made of a material having excellent heat resistance and a high coefficient of thermal expansion.

In another preferred embodiment of the device of the present invention,
A pressurized fluid injection nozzle forming a pressurizing means is connected to one opening end of the tubular body, and an openable / closable valve is connected to the other opening end of the tubular body, and the pressurized fluid injection nozzle is formed after the molding is completed. By further injecting it and discharging it from the valve, the cooling medium is caused to flow into the cylindrical body to rapidly cool the molded product.

[0020]

Since the cavity in the mold is depressurized to a predetermined degree of vacuum in advance, the degree of freedom of movement when the tubular body to which the internal pressure is applied expands is improved. Therefore, even a product having a complicated shape can be molded to have a uniform wall thickness.

Even during the internal pressure molding, the cavity inside the mold is evacuated from the outside of the molding material so that the air entering through the gap on the parting surface of the mold member is exhausted and the molding material is completely adhered to the inner surface of the mold. Because you can
The outer diameter dimensional accuracy of the molded product is improved.

The connection between the cylindrical body and the pressurized fluid injection nozzle is made through a joint member formed of a material having excellent heat resistance and a high coefficient of thermal expansion, whereby a molding material having a thermoplastic resin as a matrix is formed. When the is heated to a desired molding temperature, the joint member thermally expands. Therefore, the diameter of the through hole is reduced, the connection between the cylindrical body and the pressurized fluid injection nozzle is made more airtight, and leakage of pressurized fluid such as nitrogen gas is prevented.

A pressurizing fluid injection nozzle is connected to one opening end of the cylindrical body, and an openable / closable valve is connected to the other opening end, so that the cooling medium is passed through these nozzles and valves after the molding is completed. Can be made to flow into the cylinder, and the molded product can be rapidly cooled.

[0024]

EXAMPLE In this example, 5 continuous carbon fibers as reinforcing fibers were added to a nylon resin continuous fiber as a matrix resin.
A Ny6 / CF round-casting blade material obtained by mixing and assembling 0% by weight of fibers is used as a molding material, and this is intended to be molded into a hollow body having a diameter-expanded central portion.

As shown in FIG. 1, the upper mold 1 and the lower mold 2 made of aluminum alloy are configured to define a mold cavity 3 corresponding to the outer shape of the hollow body to be molded. .. That is, in the central portions of the upper mold 1 and the lower mold 2, the concave portions 1a and 2a corresponding to the expanded diameter portion of the molded product are formed.
Are formed.

The molding material 4 is laminated and wound in three layers so as to cover the tube 5 made of fluororubber having a thickness of 1 mm and wound around the tube 5, and the joint members 6 and 7 are attached to both open ends. , Placed on the lower mold 2. Joint members 6, 7
Is made of tetrafluoride resin having excellent heat resistance and a large coefficient of thermal expansion. The outer diameter is smaller than the outer diameter, and the inner diameter at the outermost end is larger than the outer diameter of the fluororubber tube 5.

A nozzle 8 connected to a nitrogen gas supply source (not shown) is inserted into one joint member 6, and an openable / closable valve 9 is inserted into the other joint member 7. The nozzle 8 and the valve 9 are densely inserted into both open ends of the fluororubber tube 5. As described above, since the joint members 6 and 7 are opened in a tapered shape, the work of inserting and connecting the nozzle 8 and the valve 9 can be easily performed.

Further, referring to FIG. 2, a groove 10 communicating with the mold cavity 3 and extending in a substantially orthogonal direction is formed on the inner surface of one mold, in the illustrated embodiment, the upper mold 1. This groove 1
0 is an exhaust passage 11 extending vertically through the upper mold 1
The upper end opening of the exhaust passage 11 is connected to a vacuum pump (not shown).

In FIG. 2, reference numeral 12 denotes a heating element, which is embedded in the periphery of the mold cavity 3.

FIG. 3 shows a state in which the mold is closed to define the mold cavity 3 between the upper mold 1 and the lower mold 2, and the nozzle 8 and the valve 9 are attached.

In this state, the mold cavity 3 is moved by 5 to 10 through the exhaust passage 11 and the groove 10 by the vacuum pump.
The pressure is reduced to a degree of vacuum of torr and the entire mold is heated by the heating body 12 to the optimum molding temperature of the molding material 4 of 250 to 2.
Heat to 55 ° C.

When the entire mold is heated, the joint members 6 and 7 made of tetrafluororesin are thermally expanded. Since these joint members 6 and 7 are constrained by the O-rings 13 and 14 arranged in the mold and do not expand in the circumferential direction, the thermal expansion action reduces the inner diameter of the nozzles 8 and the valve 9. The fitting state of the fluororubber tube 5 with respect to both open ends becomes more solid, and the gas sealing property at the time of pressurization described later becomes good.

Further, since the mold cavity 3 is in a vacuum state, it is possible to prevent deterioration of the physical properties of the molded product due to oxidation of the nylon resin, which is the matrix of the molding material 4, during molding.

After the predetermined degree of vacuum and molding temperature are obtained in this way, nitrogen gas for pressurization is injected from the nitrogen gas supply source into the fluororubber tube 5 through the nozzle 8,
The fluororubber tube 5 is expanded by applying a pressure of 4 to 1 MPa to bring the molding material 4 into close contact with the inner surface of the mold, as shown in FIG.

Even while the internal pressure molding is carried out in this way, the vacuum pump can continue to evacuate. As a result, when the mold clamping is insufficient, the upper mold 1 and the lower mold 2
Air entering from the gap on the parting surface of
Since the gas can be exhausted through the exhaust passage 11 and the groove 10, the molding material 4 is completely adhered to the inner surface of the mold,
The outer diameter dimensional accuracy of the molded product becomes extremely good.

After performing the internal pressure molding while maintaining the pressurized state for a certain period of time, the mold is cooled and the solidified molded product is taken out from the mold. The fluororubber tube 5 remaining inside the molded product can be easily pulled out and can be reused. In this way, the molded product 15 as shown in FIG. 5 is obtained.

Although the mold can be cooled by any means, according to the present embodiment, since the openable / closable valve 9 is inserted into one end of the fluororubber tube 5, after the completion of molding,
A cooling medium such as water or air can be made to flow from the nozzle 8 to the valve 9 in the open state, and the molded article 1
5 can be quenched. As a result, the molding cycle is shortened, the productivity is improved, and the molding material 4
Even when a crystalline resin such as nylon is used as the matrix, it is possible to prevent the physical properties of the molded product from being deteriorated due to internal strain accompanying the growth of crystals.

The structure of the present invention is not limited to the embodiment described above, and various modifications can be made. For example, when heating the molding material, a heating element system with a built-in mold is used in which a heating element is embedded in the mold, but an external heating method in which the mold is placed in a high-temperature furnace for heating may be used.

[0039]

EFFECTS OF THE INVENTION According to the present invention, even if a product having a complicated shape has a uniform thickness and internal defects such as voids are generated even by making a slight improvement to the conventional internal pressure molding method. In addition, it can be molded with good external dimension accuracy.

Depressurizing the cavity in the mold is
Not only does it contribute significantly to the molding of products with complex shapes, but it is also effective in preventing the matrix resin of the molding material from oxidizing and exhibiting its desired physical properties.

By using the joint member made of a material having a large coefficient of thermal expansion, the connection between the cylindrical body and the pressurizing means is completely gas-sealed.

By connecting a valve that can be opened and closed to one opening end of the cylindrical body so as to face the pressurizing means, the cooling medium can be made to flow into the cylindrical body after the completion of molding, and the molded product is rapidly cooled. can do. As a result, the molding cycle can be shortened and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a device configuration according to an embodiment of the present invention.

FIG. 2 is a central longitudinal sectional view showing an upper mold in the apparatus of FIG.

FIG. 3 is a cross-sectional view showing a state where the apparatus of FIG. 1 is clamped.

FIG. 4 is a cross-sectional view showing a state of the device of FIG. 1 during pressurization.

5 is a perspective view showing a molded product molded by the apparatus of FIG. 1. FIG.

[Explanation of symbols]

 1 Upper Mold 2 Lower Mold 3 Mold Cavity 4 Molding Material 5 Fluoro Rubber Tube 6 Joint Member 7 Joint Member 8 Nozzle 9 Valve 10 Groove 11 Exhaust Path 12 Heater 13 O Ring 14 O Ring 15 Molded Product

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Yoshiyoshi Toyoshima, 3-chome, Kyobashi 3-chome, Chuo-ku, Tokyo Within Jamme Sewing Machine Co., Ltd. Toyobo Co., Ltd. Research Institute (72) Inventor Mikiya Hayashibara 2-1-1 Iida, Otsu City, Shiga Prefecture Toyobo Research Co., Ltd.

Claims (7)

[Claims] 1. A molding material comprising a molding material made of a fiber reinforced resin disposed around a cylinder made of a material having good flexibility and excellent heat resistance, and expanding the molding material by applying an internal pressure to the cylinder. In the method for producing a hollow fiber-reinforced resin molded article by pressing on the inner surface of the mold to solidify or cure, the hollow body characterized by pressurizing the cylindrical body after depressurizing the cavity in the mold to a predetermined vacuum degree. A method for producing a fiber-reinforced resin molded product. 2. The method for producing a hollow fiber-reinforced resin molded product according to claim 1, wherein the cavity in the mold is evacuated from the outside of the molding material while the cylinder is being pressurized. 3. An openable / closable mold configured to provide a cavity corresponding to the outer shape of a hollow fiber-reinforced resin molded product to be molded when the mold is closed, and a molding material having good flexibility and having a molding material inserted thereinto. A pressurizing means for injecting a pressurizing fluid from at least one opening end of the tubular body made of a material having excellent heat resistance to expand the tubular body by internal pressure, and an internal pressure for the tubular body by the pressurizing means. And a decompression means for decompressing the inside of the cavity before expanding the hollow fiber-reinforced resin molded product. 4. The depressurizing means also expands the tubular body by the internal pressure by the pressurizing means to perform internal pressure molding,
The apparatus for producing a hollow fiber-reinforced resin molded product according to claim 3, which is operated to evacuate the cavity from the outside of the molding material. 5. A groove formed in a parting surface of one or both mold members of the mold so that the pressure reducing means communicates and extends over substantially the entire length of the cavity, and communicates with this groove. The apparatus for producing a hollow fiber-reinforced resin molded product according to claim 3 or 4, comprising an exhaust passage opened to an outer surface of the mold member and a vacuum pump connected to the opening of the exhaust passage. 6. A joint member having a through hole into which the open end of the cylindrical body is inserted from the inside is arranged in the mold, and a pressurized fluid injection nozzle forming the pressurizing means is provided from outside the through hole. The hollow fiber-reinforced resin molded article according to claim 3, wherein the joint member is inserted and connected to the open end of the tubular body, and the joint member is formed of a material having excellent heat resistance and a high coefficient of thermal expansion. Manufacturing equipment. 7. A pressurized fluid injection nozzle forming the pressurizing means is connected to one opening end of the cylindrical body, and an openable / closable valve is connected to the other opening end of the cylindrical body,
7. The hollow shape according to claim 3, wherein after the molding is completed, the cooling medium is injected through the pressurized fluid injection nozzle and discharged through the valve to flow the cooling medium into the cylindrical body to rapidly cool the molded article. Equipment for manufacturing fiber-reinforced resin molded products.