JP3359789B2 - Pressure bag for internal pressure molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure bag used for forming fishing rods, ski poles, golf shafts, tennis racket frames, and other tubular bodies using a thermosetting resin. is there. This pressure bag is used when a thermosetting resin sheet is wrapped around its outer periphery, inserted into a molding die, and the thermosetting resin sheet is pressed from inside toward the inner surface of the molding die to be molded.

[0002]

2. Description of the Related Art Conventionally, when a hollow tubular article as described above is formed of a thermosetting resin, a thermosetting resin and reinforcing fibers are placed in a mold having an inner surface in the shape of a target product. A mixed thermosetting resin sheet, a thermosetting resin sheet prepared by laminating a thermosetting resin sheet in which a reinforcing fiber is prepregged with a thermosetting resin or a sheet-shaped thermosetting resin and a reinforcing fiber sheet, It is known that a pressure bag having rubber elasticity is arranged inside the pressure bag.

According to this method, a mold is heated, and when the thermosetting resin sheet has appropriate plasticity, a pressurized fluid is injected into the pressure bag at an appropriate speed to expand under pressure. The thermosetting resin sheet is plastically deformed at a target thickness and a change amount so as to adhere to the inner surface of the mold. A pressure bag for internal pressure molding used at the time of such molding is conventionally known.

[0004] In such a pressure bag, the pressure of the fluid introduced into the inside is increased to reduce the voids of the thermosetting resin sheet as much as possible, thereby increasing the density of the molded product . Then, after the thermosetting resin sheet is heat-cured for a predetermined temperature and time, it is taken out from a molding die, and a pressure bag is taken out from a molded product. The feature of such a molding method is that it has been widely used since a hollow, high-density molded article having a complicated shape can be produced with relatively simple equipment.

[0005] Also, there are known conventional ski poles, fishing rods, golf shafts, tennis rackets and other general tubular bodies provided with inflection points. The inflection point expands a part of the length of the golf shaft or the like in the length direction outwardly from the other part without changing the film thickness to form a larger diameter. As described above, when an inflection point is formed by increasing the diameter of a part of the tubular body and expanding it outward, elastic deformation, that is, a position deviated from the center of the tubular body toward the end from the center is obtained. A bending point will occur. for that reason,
It is known that when a hit is performed using such a golf shaft, the tubular body is elastically deformed and elastically bent from the bending point, and various advantages such as generating a strong repulsive force are known. I have.

Conventionally, a tubular body having such an inflection point is formed by a pressure bag having the same overall film thickness. However, the fact that the entire film thickness is the same is not exactly the same in a strict sense, but is recognized as being molded identically,
In reality, it is technically impossible to strictly equalize the film thickness, or the film thickness becomes extremely expensive if possible. For this reason, there are situations where the film thickness is small in some parts of the pressure bag or large in some parts of the pressure bag. Is inevitable. Moreover, it has been impossible to specify which part of the pressure bag is thick or small.

[0007]

Therefore, when the thermosetting resin sheet wound around the outer periphery is pressed against the inner surface of the mold using a pressure bag having a non-uniform film thickness, the following situation occurs. Will occur.

That is, when the inner diameter of the pressure bag is the same and the film of the pressure bag is homogeneous, the pressure bag starts to expand from a portion where the film thickness is small. If the pressure is continuously applied in the free space, the expansion progresses differently depending on the degree of the difference between the film thickness of a certain specific portion before expansion and the surrounding film thickness. That is, when the difference between the thin portion of the specific portion and the thickness of the surrounding portion is small, the expansion propagates to the surroundings, and the entire portion expands substantially equally.

When the difference between the thin film thickness of the specific portion and the peripheral film thickness is large, only the thin portion of the specific portion expands. Therefore, a pressure bag in which a thermosetting resin sheet is wrapped around the periphery is inserted into a mold, and a pressure fluid is introduced into the pressure bag to expand the pressure bag. Start.

Therefore, the part where the inflation starts is different depending on the pressure bag, and it has been impossible to control the inflation conventionally. As a result, in the mold of the tubular body provided with the above-mentioned inflection point, as shown in FIG. 5, the inflection point is formed on the inner surface of the molding die (1) by the concave portion (2).
Is formed as

Then, a molding die (1) corresponding to the inflection point
When the inflation of the pressure bag (3) starts from a portion other than the concave portion (2), as shown in FIG. 5, the concave portion (2) corresponding to the inflection point is formed while the air is left. The thin portion of the pressure bag (3) corresponding to the portion other than (2) expands. Due to this inflation, the pressure bag
In (3), both ends in the length direction are pressed together with the thermosetting resin sheet (4) to the inner surface of the molding die (1) through the concave portion (2) to make close contact. As a result, an air-sealed portion (7) is formed in the space between the expansion contact points (5) and (6) including the concave portion (2).

Even if the corresponding inflection portion (8) of the pressure bag (3) corresponding to the inflection point eventually expands,
The concave portion (2) at the portion corresponding to the inflection point is already an air sealing portion (7). Therefore, the shape corresponding to the concave portion (2) of the mold (1) is formed by the pressure of the air.
Thermosetting resin sheet (4) and pressure bag (3)
Becomes something that cannot be transformed.

If the accumulation amount of air in the sealing portion (7) including the concave portion (2) is large, the thermosetting resin sheet (4) and the pressure bag (3) cannot be deformed at all, and the molding die
It becomes impossible to cope with the concave portion (2) of (1). Even when the amount of air accumulated in the sealing portion (7) including the concave portion (2) of the molding die (1) is relatively small, the inner surface of the concave portion (2) corresponding to this inflection point is formed. Is a thermosetting resin sheet (4)
Inserted from close contact to it can not be the existence of air over the, or the surface corresponding to the inflection point of the tubular body roughened, the drawback to be that would form different inflection point from the design value Had.

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem, and when the pressure bag (3) is inflated, a corresponding inflection portion corresponding to the concave portion (2) of the molding die (1).
(8) is inflated first and this pressure bag
With the expansion of (3), the thermosetting resin sheet (4) is molded
First, after pressing and inserting into the concave portion (2) corresponding to the inflection point of (1), the other portion is expanded, and the thermosetting resin sheet (4) is uniformly formed in the molding die (1) . It is intended to be able to press tightly against the inner surface.

[0015]

According to the present invention, in order to solve the above-mentioned problems, a thermosetting resin sheet is wound around the outer periphery, inserted into a molding die, and a pressure fluid is introduced thereinto. In a pressure bag for internal pressure molding, in which the thermosetting resin sheet is pressed and adhered to the inner surface of the molding die by being pressurized and expanded, the thermosetting resin sheet wound around the outer periphery is formed and cured. The thickness of the corresponding inflection portion corresponding to the inflection point is formed to be smaller than the surrounding thickness.

A thick portion having a larger thickness than the surrounding portion may be formed on the fluid introduction side of the corresponding inflection portion.

Further, the corresponding inflection portion may be arranged in a range of 0 to 15 mm from the maximum diameter portion of the inflection point after molding and curing of the thermosetting resin sheet toward the tip end.

[0018]

Since the present invention is constructed as described above, in order to form a tubular body having an inflection point using a pressure bag, first, a metal core is inserted into the pressure bag. A thermosetting resin sheet is wound around the outer periphery of the pressure bag into which the core metal is inserted by a winding machine. In this winding, the thickness is not particularly increased or thinned at the inflection point portion, and the winding is performed according to the same standard as the other portions.

After the core is removed from the pressure bag, an inlet nozzle for introducing a fluid is attached to the fluid inlet of the pressure bag. Next, the introduction nozzle is attached, and a pressure bag having a thermosetting resin sheet wound around the outer periphery is set at a predetermined position of a mold heated to a predetermined temperature. And the upper mold, lower mold,
Alternatively, the other mold is closed, and a fluid such as air, nitrogen gas, or water is introduced from the introduction nozzle into the pressure bag at a predetermined speed and a constant pressure to inflate the pressure bag.

Due to this expansion, the thermosetting resin sheet becomes
It is firmly pressed on the inner surface of the molding die and becomes dense.
In the inflation of the pressure bag, the thickness of the corresponding inflection portion corresponding to the concave portion at the inflection point is formed thinner than the other portions. Expands, and the corresponding inflection portion of the pressure bag presses and deforms the thermosetting resin sheet into the concave portion corresponding to the inflection point of the mold.

Therefore, the air existing in the concave portion corresponding to the inflection point of the mold is first removed and moves to another portion. Then, during this movement process, it is appropriately discharged to the outside. In addition, since the order of inflation of the pressure bag can be controlled by sequentially changing the thickness of the pressure bag, the pressure bag can be inflated and deformed sequentially from one side to the other side. It is easy to remove the air present in the mold to the outside.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. (3) is a pressure bag, which uses a heat-resistant natural rubber thiuram precured latex. In principle, the pressure bag (3) is formed to have a substantially uniform film thickness over the entire length. However, the mold (1)
Forming an inflection point of you molded tubular body to form a recess (2). At the corresponding inflection portion (8) of the pressure bag (3) corresponding to the concave portion (2), the film thickness is formed smaller than the surrounding film thickness. This thin film thickness is a manufacturing error of the thickness caused in the film thickness of other portions formed uniformly, and must be thinner than the expected thinnest portion.

Also, on the fluid introduction side of the corresponding inflection portion (8),
A thick portion (9) having a larger thickness than the surroundings is formed. Due to the presence of the thick portion (9), reliable expansion from the corresponding inflection portion (8) is guaranteed.

The corresponding inflection portion (8) of the pressure bag (3) is a maximum diameter portion of the inflection point of the thermosetting resin sheet (4) after molding and curing, that is, a maximum diameter of the concave portion (2). It is formed by arranging it in the range of 0 to 15 mm from the part toward the tip. This range is preferably as close to 0 as possible, but if the range is 15 mm from the maximum diameter portion toward the distal end portion, the sealing portion (7) will not be formed.

Then, a thermosetting resin sheet (4) is wound around the outer periphery of the pressure bag (3). In winding the thermosetting resin sheet (4), a metal core (not shown) is inserted into the inside in order to maintain the shape of the pressure bag (3). A thermosetting resin sheet (4) in which a thermosetting resin and carbon fiber are mixed, and a carbon fiber sheet laminated on a sheet-like thermosetting resin are provided around the outer periphery of the pressure bag (3) into which the core metal is inserted. forming thermosetting tree Aburashi over preparative (4) which is, or carbon fiber sheet winding Purifureigu the thermosetting resin sheet (4) with a thermosetting resin.

In this state, the core metal is removed from the pressure bag (3), and an inlet nozzle (12) cooled to room temperature is attached to the opening (11) of the pressure bag (3) as shown in FIG. The introduction nozzle (12) penetrates an introduction path (13) for introducing a liquid such as air, nitrogen gas, or water in a central axial direction, and can introduce a pressurized fluid into the pressure bag (3). It is formed as follows.

Next, the introduction nozzle (12) is mounted, and a pressure bag (3) having a thermosetting resin sheet (4) wrapped around the outer periphery is mounted in a molding die (1). This mold (1)
Is heated to a temperature necessary for curing the thermosetting resin, and is formed by an upper mold and a lower mold or a mold divided into a plurality of molds as necessary. The molding die (1) has a packing (14) for pressing and fixing the outer periphery of the opening (11) of the pressure bag (3) to the outer periphery of the introduction nozzle (12). Also, adjacent to this packing (14),
An annular flange that fits into the outer annular groove (15) of the introduction nozzle (12)
(16) is projected to stably fix the introduction nozzle (12).

Next, after the mold (1) is tightened, pressurized fluid is introduced from the introduction nozzle (12) to expand the pressure bag (3). In this expansion, the thermosetting resin sheet (4) is strongly pressed from the inside by the pressure bag (3) to the inner surface of the mold (1), and is thermoset densely.

The inflation of the pressure bag (3) is caused by the corresponding inflection portion (8) having a smaller thickness than other portions.
First, the thermosetting resin sheet (4) expanded and wound around the outer periphery is pressed into the concave portion (2) of the mold (1). The air present in the concave portion (2) of the molding die (1) by this pressure is pushed out without any hindrance to the deformation of the thermosetting resin sheet (4), and the pressure bag (3) is inflated. With the deformation, they are sequentially extruded to the outside of the molding die (1).

As described above, since the thickness of the corresponding inflection portion (8) corresponding to the inflection point of the tubular body to be formed is formed thin, air can be surely blown from the concave portion (2) in the molding die (1). By excluding it, the thermosetting resin sheet (4) can be deformed along the recess (2), and the inflection point can be reliably formed.

[0031]

As described above, according to the present invention, it is difficult to form an inflection point due to the sealing of air in the concave portion, which has been caused by an unspecified non-uniform film thickness of the pressure bag. It is possible to form an inflection point in the tubular body as designed, without forming a rough surface due to an air pocket or making it difficult to form an inflection point in the point formation part.

Further, such a technical effect is made possible by changing the thickness of the pressure bag at the design stage, and the manufacturing process of the tubular body is not complicated at all as before. .

[Brief description of the drawings]

FIG. 1 is a partially enlarged view showing a corresponding inflection point portion of a pressure bag according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an inflection point showing a state in which a pressure bag having a thermosetting resin sheet wound around the outer periphery is mounted in a molding die.

FIG. 3 is a partially enlarged sectional view showing a state of a concave portion of a molding die when a pressure bag according to an embodiment of the present invention is pressurized and inflated.

FIG. 4 is a schematic diagram showing a relationship between a pressure bag, a thermosetting resin sheet, and a molding die when a tubular body is formed using the pressure bag.

FIG. 5 is a partially enlarged cross-sectional view showing a concave portion of a mold when inflated and pressurized using a conventional pressure bag.

[Explanation of symbols]

1 the mold 4 thermosetting resin sheet 8 corresponding inflection portion 9 thick section

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 43/10 B29C 43/32-43/36 B29C 70/40-70/44 B29D 23/00

Claims (3)

(57) [Claims] In a state where a thermosetting resin sheet is wound around an outer periphery and inserted into a molding die, a pressure fluid is introduced into the molding die to expand under pressure, whereby the thermosetting resin sheet is formed on the inner surface of the molding die. In a pressure bag for internal pressure molding, which is pressed and adhered to the inner surface, the thickness of the corresponding inflection portion corresponding to the inflection point after the molding and curing of the thermosetting resin sheet wound around the outer periphery is determined. A pressure bag for internal pressure molding characterized by being formed thinner than the film thickness. 2. The pressure bag for internal pressure forming according to claim 1, wherein a thick portion having a larger film thickness than the surrounding portion is formed on the fluid introduction side of the corresponding inflection portion. 3. The corresponding inflection portion is formed of a thermosetting resin sheet.
From the maximum diameter at the inflection point after molding and hardening to 0
2. The pressure bag for internal pressure molding according to claim 1, wherein the pressure bag is arranged in a range of 15 mm.