JPH0970842A - Pressure bag for internal pressure molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the rupture generated under various conditions and to certainly pressurize a thermosetting resin sheet without generating rupture in a pressure bag obtained by the pressure molding of the thermosetting resin sheet by inserting and arranging the thermosetting resin sheet wound around an outer periphery in a mold. SOLUTION: In a pressure bag 1 for internal pressure molding, a stopper part 14 protruding so as to make a film thick is formed to the outer periphery of the part corresponding to the inside of the leading end part 5 of a thermosetting resin sheet 6 wound around the outer periphery and the film is formed so that the thickness thereof becomes large successively from the stopper part 14 to the bottomed part 7 of the leading end protruding part 10 protruding to the outside of the thermosetting resin sheet 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal pressure molding used for molding ski poles, tennis racket frames, fishing rods, golf shafts and other tubular bodies and hollow tubular thermosetting resin. The present invention relates to a pressure bag.

[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 preformed in a molding die whose inner surface has the shape of a desired product. And a reinforcing fiber mixture, a sheet in which reinforcing fibers are pre-prepared with a thermosetting resin or a laminate of sheet-like thermosetting resin and reinforcing fiber sheets is set, and a pressure bag having rubber elasticity is arranged inside thereof. Are known.

According to this method, the mold is heated, and when the thermosetting resin has an appropriate degree of plasticity, a pressurized fluid is injected into the pressure bag at an appropriate rate to expand by pressure. The curable resin sheet is intended to be plastically deformed with a desired thickness and change amount, and brought into close contact with the inner surface of the molding die. An internal pressure molding pressure bag used for such molding has been conventionally known.

In such a pressure bag, the pressure of the fluid introduced therein is increased to reduce the voids of the thermosetting resin and the reinforcing fibers as much as possible, and the density of the molded product is increased. Then, after thermosetting the thermosetting resin at a predetermined temperature and time, the thermosetting resin is taken out from the molding die and the pressure bag is taken out from the molded product. The feature of such a molding method is that it is used more frequently than before because a hollow, high-density molded product having a complicated shape can be manufactured with relatively simple equipment.

[0005]

However, since the pressure bag is made of a material having rubber elasticity, and in particular, a material mixed with natural rubber is often used, it causes rupture at a predetermined pressurizing step. There have been many things in the past. When this rupture occurs, the pressure of the pressure bag against the thermosetting resin sheet is interrupted, and the product cannot be used as a product. Therefore, not only the thermosetting resin is wasted, but also the production efficiency is significantly deteriorated.

Conventionally, in this type of molding method, the countermeasure against the rupture of the pressure bag has been an extremely important problem, but the problem cannot be solved.
According to the research conducted by the present inventors, the rupture of the pressure bag includes a rupture at the side surface and a rupture at the tip protruding portion.

In the rupture of the side surface of the pressure bag, generally, when the inner diameter is the same and the film thickness is uniform,
When a fluid is introduced and pressure is applied, expansion starts from the portion where the film thickness is thin. If the pressure is continuously applied in the free space, the progress of expansion will differ depending on the degree of the difference between the film thickness of a specific portion before expansion and the film thickness of the surrounding area. That is, when the difference in the film thickness between the thin part of the specific part and the surrounding is small, the expansion propagates to the surroundings, and the expansion expands almost equally. Further, when the difference between the thin film thickness portion and the surrounding film thickness of the specific portion is large, only the thin film thickness portion expands.

Further, in the case of a narrow space such as a pressure bag in the molding die, a more complicated expansion method is required. That is, the present inventor has inserted the pressure bag into the mold and inflated it, and analyzed the movement thereof.

When the pressure bag is inflated from the side opposite to the bottom portion formed at the tip, that is, from the direction of introduction of the pressurized fluid, the pressure bag expands in the tip direction, and the portion contacting the inner surface of the molding die is expanded. It will not expand and move further. When the pressurization is continued, the non-contact portion with the adjacent inner surface of the molding die expands, contacts the inner surface of the molding die, and stops the expansion. By repeating this in sequence, expansion proceeds toward the tip of the pressure bag, and the bottomed portion of the tip of the pressure bag moves toward the tip in the forming die.

When the tip projection of the pressure bag finally expands and comes into contact with the tip of the inner surface of the molding die, the expansion of the pressure bag stops and the movement of the tip projection also stops. In this case, there is no change even if the pressure is increased to 10 kg / m ² .

From the above analysis, as shown in FIG. 4, when fluid pressure is applied to the pressure bag (1), the thin film portion (3) of the pressure bag (1) expands,
Rupture (4) occurs when the extension limit is exceeded. This burst
(4) is likely to occur because there is a large space between the tip (5) of the thermosetting resin sheet (6) wound around the outer periphery of the pressure bag (1) and the gap between the mold (2). Becomes

Further, if the expansion stops before the limit of expansion, no rupture occurs. When the expansion stops, the thin portion (3) of the pressure bag (1) expands and hits against the thermosetting resin sheet (6). Indicates a state where expansion of the thin film portion (3) is impossible. In this state, even if pressure is applied to the inside of the pressure bag (1), expansion of the pressure bag (1) is blocked by the molding die (2), so that the pressure bag (1) does not deform and does not burst.

From the above, the mechanism of rupture of the side surface of the pressure bag (1) is considered as follows. That is, the pressure bag is attached to the tip portion (5) of the thermosetting resin sheet (6) wrapped around the outer circumference of the pressure bag (1).
When there is a portion with a large film thickness in (1), the portion adjacent to this portion with a large film thickness expands, and when the difference in film thickness is large, only the portion with a small film thickness (3) It expands and ruptures when the extension limit is exceeded. This state is shown in FIG. Then, when the expansion of the thin portion (3) reaches a dead end before reaching the limit of extension, that is, when it hits against the thermosetting resin sheet (6), the thermosetting resin sheet
(6) prevents expansion and does not burst when expansion stops.

In view of the mechanism of rupture occurring on the side surface of the pressure bag (1) described above, the pressure bag
The rupture of the tip protrusion (10) of (1) is considered to occur due to the following mechanism.

The pressure bag (1) expands sequentially from the direction of introduction of the pressurized fluid, and this expansion reaches the bottomed part (7) at the tip of the pressure bag (1), and the expansion and the bottomed part (7).
The movement is stopped in the mold (2). When there is a space between the tip of the pressure bag (1) and the tip (8) of the inner surface of the molding die (2), even if the pressure reaches 10 kg / m ² , for example, expansion and tip movement may occur. Absent. This is because the tensile strength of the rubber is larger than the pressure for expanding, that is, the force of 10 kg / m ² .

In this state, when the temperature of the tip protruding portion (10) of the pressure bag (1) reaches the temperature at which the plasticization of the rubber starts due to the heating of the molding die, for example, 150 ° C. or more,
The plasticization of the pressure bag (1) begins, the resistance to strength decreases, and the bag bursts. The rupture at this time is not a burst due to exceeding the elastic limit of rubber as in the rupture of the side surface, but is caused by buckling or displacement occurring in the plasticized substance. This can be said from the fact that when the broken parts of the ruptured product of the tip protruding portion (10) are analyzed, it cannot be seen after the expansion and burst to the elastic limit.

In order to prevent the pressure bag (1) from bursting at the tip projection (10), the bottomed portion (7) of the tip projection (10) of the pressure bag (1) is molded before plasticization begins. It may be brought into contact with the tip (8) of the inner surface of (2). The space generated between the bottomed portion (7) of the tip protruding portion (10) of the pressure bag (1) and the tip protruding portion of the inner surface tip (8) of the molding die (2) is defined as an extra extension length (11). Name it.

As described above, in order to prevent the tip protrusion (10) of the pressure bag (1) from rupturing, the bottomed portion (7) of the tip protrusion (10) is fixed to the molding die (2) before plasticization begins. It is sufficient to bring the tip of the inner surface (8) of () into contact with the tip of the pressure bag (1) and the inner tip (8) of the molding die (2) theoretically. 11) so as not to form
The pressure bag (1) may be placed in the molding die (2).

However, in reality, this extra length
(11) is not formed, or an extra elongation length of 4 mm or less that does not cause rupture, which has been found by the inventors' experiments.
(11) is practically difficult.

If the relationship between the pressure bag (11) and the molding die is designed so that no extra stretch is generated, the pressure bag (rather than the internal dimension of the molding die should be adjusted due to manufacturing error or the like). 1) Tip protrusion (10)
If the dimension is long, the pressure bag (1) is deformed when the pressure bag (1) is inserted into the mold, and if the mold (2) is a split mold, the butted mold ( A part of the pressure bag (2) is caught in the space of 2) and is mixed, which causes a rupture.

In the pressure bag (2), a core metal (not shown) is inserted inside when the thermosetting resin sheet (6) is wound around the pressure bag (2).
In many cases, the core metal is inserted in a direction in which the pressure bag (1) is slightly stretched when the core metal is inserted. Since the thermosetting resin sheet (6) is wrapped around the outer periphery of the pressure bag (1) in a stretched state, the stretched state is maintained when the core metal is pulled out and inserted into the molding die (2). ing. Then, by heating the mold (2), the pressure bag (1) contracts to the state before being stretched by the core metal. Due to this heat shrinkage, the bottomed part (7) of the pressure bag (1) and the tip of the inner surface of the molding die
An air gap is generated between (8) and the extra elongation length (11), or the existing extra elongation length (11) is increased.

When the pressure bag (1) having the thermosetting resin sheet (6) wound around the outer periphery thereof is set in the molding die (2), a plurality of pressure bags (1) are molded.
It is common to set in (2) at the same time and perform molding.
In that case, if the setting is done slowly, the thermosetting of the thermosetting resin sheet (6) set earlier will proceed before the pressurization, so it is necessary to set it quickly, and the extra elongation It is practically difficult to accurately set a plurality of pressure bags (1) so that (11) becomes zero or becomes 4 mm or less.

The present invention, as described above, includes a pressure bag.
Between the tip of (1) and the tip of the inner surface (8) of the molding die (2), the extra length of extension (11), the inner peripheral surface of the molding die (2) and the outer peripheral surface of the pressure bag (1). Due to the presence of voids or the like generated between the pressure bag (1) and the mold (2), only a part of the pressure bag (1) is inflated to prevent rupture. And a thermosetting resin sheet wrapped around the outer periphery
It is intended to surely press and compress (6) on the inner surface of the molding die (2) so that the thermosetting resin sheet (6) can be surely pressure-molded.

[0024]

In order to solve the above-mentioned problems, the present invention introduces a pressure fluid into the mold with a thermosetting resin sheet wound around the outer periphery and inserted and arranged in a molding die. In a pressure bag for internal pressure molding, in which the thermosetting resin sheet is pressed and brought into close contact with the inner surface of the mold by expanding by pressure, it corresponds to the inside of the tip of the thermosetting resin sheet wrapped around the outer periphery. On the outer periphery of the part, a stopper part with a thicker film thickness is formed, and the film thickness is gradually increased from this stopper part to the bottom part of the tip protruding part protruding outward of the thermosetting resin sheet. It is formed.

[0025]

EXAMPLE An example of the present invention will be described below. (1) is a pressure bag, which is made of a material such as natural rubber and whose diameter and length are determined according to the object to be pressure-molded. You can do it. For example, it can be used to form fishing rods, golf shafts, tennis racket frames, ski poles, and other general tubular bodies. However, depending on the required length, it is possible to determine the length and diameter. it can.

The pressure bag (1) has an opening at one end thereof, into which an introduction nozzle (12) for introducing a fluid such as air, nitrogen gas or liquid can be attached.
(13). Further, the tip of the tip protruding portion (10) is formed as a bottomed portion to form a bottomed portion (7) so that the pressure bag (1) can be inflated by the fluid introduced from the opening portion (13). ing.

The pressure bag (1) is a thermosetting resin sheet in which reinforcing fibers and thermosetting resin are mixed.
(6), a thermosetting resin sheet (6) in which reinforcing fibers are pre-prepared with a thermosetting resin, a thermosetting resin sheet (6) in which reinforcing fibers and a thermosetting resin are laminated in a sheet shape, and the like are wound. However, on the outer periphery of the tip protruding portion (10), a stopper portion (14) having a thick film thickness and protruding to the outer periphery is formed.

When the thermosetting resin sheet (6) is wound around the outer periphery of the pressure bag (1), the stopper portion (14) is disposed inside the thermosetting resin sheet (6) in the direction of the tip. Is formed. Then, the tip end protruding portion (10) of the pressure bag (1) protrudes outward from the tip end portion of the thermoplastic resin sheet (6).

When the thermosetting resin sheet (6) is wound around the outer circumference of the pressure bag (1), the protrusion of the tip protruding portion (10) extends to which part of the pressure bag (1) the thermosetting resin sheet (6). It is necessary to project the tip projecting portion (10) because it is visually determined whether or not () is wound.

Then, as shown in FIG. 1, the tip protruding portion (10) is inserted and set in the molding die (2).
Than the pressing part of the thermosetting resin sheet (6) of the molding die (2)
It is to be inserted into the small tip diameter portion (15) having a reduced diameter. And, in the normal insertion state, the tip small diameter portion (1
In 5), the bottomed part of the tip of the pressure bag (1)
An extra length of extension (16) is formed between (7) and the inner surface tip (8) of the tip small diameter portion (15).

Further, the pressure bag (1) is formed such that the film thickness is gradually increased from the stopper portion (14) to the bottomed portion (7) arranged at the tip of the tip protruding portion (10) to form a stopper. Tip protrusion (10) continuous with part (14)
Is formed thin, and the thickness of the tip protruding portion (10) is formed thicker in the direction of the bottomed portion (7).

In order to press-mold the target product using the pressure bag (1) having the above-mentioned structure, first insert a core into the pressure bag (1). . It is preferable to insert the core metal from the mounting opening portion (13) to the bottomed portion (7) so that the pressure bag (1) is not extended if possible. However, in reality, if the core metal is securely inserted into the pressure bag (1), the core metal will be elongated to some extent.

Then, the pressure bag (1) in which the core metal is inserted is a thermosetting resin sheet (6) in which a sheet-shaped thermosetting resin is laminated on a carbon fiber sheet, or carbon fibers are pre-pregged with the thermosetting resin. The thermosetting resin sheet (6) is wrapped around the outer circumference of the pressure bag (1) by a winding machine to cover it. This thermosetting resin sheet (6) is wrapped around the pressure bag (1)
Starting from the slightly bottomed part (7) of the mounting opening (13) of
This is performed until the stopper portion (14) is covered.

The pressure bag (1) has a tip portion (10) extending from the tip portion (5) of the thermosetting resin sheet (6).
Is projected. In this state, remove the core metal from the pressure bag (1), and then insert the introduction nozzle (12) into the mounting opening (13) of the pressure bag (1) as shown in FIG.
Install as shown in. The introduction nozzle (12) can penetrate the introduction passage (17) for introducing a liquid such as air, nitrogen gas and water in the central axial direction, and can introduce a pressurized fluid into the pressure bag (1). Is formed.

Next, the introduction nozzle (12) is mounted, and the pressure bag (1) having the thermosetting resin sheet (6) wound around the outer periphery is mounted in the molding die (2). This mold (2)
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 parts as necessary. Also, the mold (2)
Is a packing for pressing and fixing the outer periphery of the opening (13) of the pressure bag (1) to the outer periphery of the introduction nozzle (12).
(18) is formed. Further, adjacent to the packing (18), an annular collar (21) fitted into the outer peripheral annular groove (20) of the introduction nozzle (12) is projected to stably fix the introduction nozzle (12).

Next, after the mold (2) is clamped, a pressurized fluid is introduced from the introduction nozzle (12) to inflate the pressure bag (1). In this expansion, the thermosetting resin sheet (6) is strongly pressed from the inside by the pressure bag (1) against the inner surface of the molding die (2), and is densely thermoset.

When the thermosetting resin sheet (6) is pressed, the pressure bag (1) is inflated, and the expansion proceeds from the tip portion (5) to the tip of the thermosetting resin sheet (6). Protrusion
In (10), the tip protruding part from the stopper part (14)
The film thickness of the pressure bag (1) is sequentially increased from the bottom part (7) through the (10).

In the pressure bag (1) formed of a material having rubber elasticity such as natural rubber, when internal pressure is applied, generally, as described above, expansion starts from the thin portion. Become. Therefore, at the tip protruding portion (10) protruding from the tip portion (5) of the thermosetting resin sheet (6), the stopper portion covered with the thermosetting resin sheet (6)
Since the tip protruding portion (10) continuous with (14) is the thinnest, the bottomed portion (7) having a large film thickness expands sequentially from this portion.
The expansion will move in the direction.

Then, the bottomed portion (7) of the tip projecting portion (10) of the pressure bag (1) moves its position according to this expansion, and the inner surface tip (7) inside the tip diameter small portion (15) of the molding die (2). 8) Move sequentially in the direction. And in this expansion process,
The bottomed portion (7) completes expansion by abutting its tip against the inner surface tip (8) of the molding die (2).

The protruding end of the pressure bag (1)
In (10), since the film thickness is gradually increased from the stopper portion (14) toward the bottomed portion (7), the expansion due to the internal pressure applied to the pressure bag (1) does not occur.
From (14) to the bottomed part (7) direction, they sequentially occur.

Therefore, as in the conventional case, the expansion is caused by the protruding end portion.
(10) is generated in the bottomed part (7) direction first, and the movement is fixed, which hinders the movement of the bottomed part (7) toward the inner surface tip (8),
The movement of the bottomed part (7) is not stopped while leaving the space of the extra length (16). Extra length as before
When the movement of the bottomed part (7) is stopped while leaving (16), the temperature inside the mold (2) rises and the temperature of the pressure bag (1) exceeds, for example, 150 ° C. At times, plasticization occurs at the tip protrusion (10) of the pressure bag (1). Then, the bottomed portion (7) or the protruding end portion
In (10), buckling or displacement due to plasticization causes rupture.

However, in the present invention, the tip protrusion (1
0) is to expand sequentially from the stopper direction, so there is a bottomed part (7) in the small tip diameter part (15) of the mold (2).
The movement of the bag is not blocked, and the pressure bag (1)
Is expanded from the stopper part (14) direction to the bottomed part (7) direction in order to expand the bottomed part (7) to the mold.
It is possible to move to the tip (8) of the inner surface of (2) and press it.

When the bottomed portion (7) hits the inner surface tip (8), even if abnormal pressure is applied to the inner surface of the pressure bag (1), the tip protruding portion (10) and the bottomed portion (8) The outer circumference of (7) is held against the inner surface of the molding die (2), so that no rupture or the like occurs. In the state where the bottomed portion (7) hits the inner surface tip (8) of the molding die (2) in this way, the thermosetting resin sheet (6) is expanded by the expansion of the pressure bag (1). , Pressed against the inner surface of the mold (2) to densify the composition, and
Good molding can be performed.

Then, after the thermosetting resin sheet (6) is pressed by the pressure bag (1) for a certain period of time, the introduction of the pressurized fluid from the introduction nozzle (12) is stopped, and the pressure bag ( Stop applying pressure to 1). Next, the molding die (2) is separated into an upper die, a lower die or a plurality of divided dies, and a molded product formed of the thermosetting resin sheet (6) is taken out. Then, by removing the introduction nozzle (12) from the molded product and then removing the pressure bag (1), a molded product of the thermosetting resin sheet (6) can be obtained.

The stopper portion (14) of the pressure bag (1) described above is a thermosetting resin sheet.
It engages and engages with the inner surface of (6). In this way, the stopper portion (14) bites into and engages with the inner surface of the thermosetting resin sheet (6), so that the thermosetting resin sheet
When winding (6) around the outer circumference of the pressure bag (1), a core metal was inserted into the pressure bag (1). At the time of insertion, when the pressure bag (1) is stretched by the core metal, that is, when the core metal hits the bottomed part (7) and the entire length of the pressure bag (1) is extended, it is thermoset. When the resin sheet (6) is wrapped around the pressure bag (1), the pressure bag
In (1), the expanded state is maintained.

Even after the core metal is pulled out from the pressure bag (1), the expanded state of the pressure bag (1) is often fixed at room temperature. However, using this pressure bag (1) with the mold (2)
When inserted and heated, the pressure bag (1) restores the expanded state to the original state due to the effect of heating. Then, due to the restoration, the interval between the bottomed portion (7) and the inner surface tip (8) of the molding die (2) is expanded, and the extra length of extension (16) is increased.

It is not preferable that the extra length of extension (16) becomes large because it causes rupture during the expansion process of the pressure bag (1) as described above. However, if the stopper portion (14) is formed on the outer periphery of the pressure bag (1) and bites into and engages with the inner surface of the thermosetting resin sheet (6) as in the present invention, the pressure bag (1) is In the thermosetting resin sheet (6), even if an expansion portion fixed by the stopper portion (14) and expanded by the core metal is restored, the restoration to the original length is prevented.

Therefore, the bottomed portion (7) and the inner surface tip (8) in the state in which the pressure bag (1) is mounted in the molding die (2) without increasing the extension length (16). It is possible to keep the distance between the two substantially and to prevent the extra length of extension (16) from being greatly expanded.

[0049]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, a pressure bag for winding a thermosetting resin sheet around the outer periphery, inserting the thermosetting resin sheet in a molding die, and press-molding the thermosetting resin sheet is provided. In this case, it is possible to prevent the rupture caused by various conditions and to reliably pressurize the thermosetting resin sheet without rupture.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tip protruding portion showing a state in which a thermosetting resin sheet is wound around the outer circumference of a pressure bag and mounted in a molding die.

FIG. 2 is a schematic cross-sectional view showing a state in which a thermosetting resin sheet is wound around the outer periphery of a pressure bag and mounted in a molding die.

FIG. 3 is a sectional view of a pressure bag.

FIG. 4 is a cross-sectional view showing a state in which a side surface of the pressure bag is ruptured.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure bag 2 Mold 5 Tip part 6 Thermosetting resin sheet 7 Bottom part 10 Tip protrusion part 14 Stopper part

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[Procedure amendment]

[Submission date] November 20, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of Invention] Pressure bag for internal pressure molding

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal pressure molding used for molding ski poles, tennis racket frames, fishing rods, golf shafts and other tubular bodies and hollow tubular thermosetting resin. The present invention relates to a pressure bag.

[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 preformed in a molding die whose inner surface has the shape of a desired product. And a reinforcing fiber mixture, a sheet in which reinforcing fibers are pre-prepared with a thermosetting resin or a laminate of sheet-like thermosetting resin and reinforcing fiber sheets is set, and a pressure bag having rubber elasticity is arranged inside thereof. Are known.

According to this method, a molding die is heated, and when the above-mentioned thermosetting resin has an appropriate plasticity, a pressurized fluid is injected into the pressure bag at an appropriate speed to expand by pressure. The curable resin sheet is intended to be plastically deformed with a desired thickness and change amount, and brought into close contact with the inner surface of the molding die. An internal pressure molding pressure bag used for such molding has been conventionally known.

In such a pressure bag, the pressure of the fluid introduced therein is increased to reduce the voids of the thermosetting resin and the reinforcing fibers as much as possible, and the density of the molded product is increased. Then, after thermosetting the thermosetting resin at a predetermined temperature and time, the thermosetting resin is taken out from the molding die and the pressure bag is taken out from the molded product. The feature of such a molding method is that it is used more frequently than before because a hollow, high-density molded product having a complicated shape can be manufactured with relatively simple equipment.

[0005]

However, since the pressure bag is made of a material having rubber elasticity, and in particular, a material mixed with natural rubber is often used, it causes rupture at a predetermined pressurizing step. There have been many things in the past. When this rupture occurs, the pressure of the pressure bag against the thermosetting resin sheet is interrupted, and the product cannot be used as a product. Therefore, not only the thermosetting resin is wasted, but also the production efficiency is significantly deteriorated.

[0006] At a molding method of the prior art of this kind, but rupture measures of pressure bag has become an extremely important issue and was not be able to see the solving of the problem.
According to the research conducted by the present inventors, the rupture of the pressure bag includes a rupture at the side surface and a rupture at the tip protruding portion.

In the rupture of the side surface of the pressure bag, generally, when the inner diameter is the same and the film thickness is uniform,
Pressurizing by introducing fluid, thickness expansion from a thin portion begins. If the pressure is continuously applied in the free space, the progress of the expansion varies depending on the degree of the difference between the film thickness of the specific portion before the expansion and the film thickness of the surrounding area. That is, when the difference in the film thickness between the thin part of the specific part and the surrounding part is small, the expansion propagates to the surroundings and expands substantially equally. Further, when the difference between the thin portion of the specific portion and the surrounding thickness is large, only the thin portion expands.

Further, in the case of a narrow space such as a pressure bag in the molding die, a more complicated expansion method is required. That is, the present inventor has inserted the pressure bag into the mold, inflated it, and analyzed the movement thereof.

When the pressure bag is expanded on the side opposite to the bottom portion formed at the tip, that is, when the pressurized fluid is introduced, the pressure bag expands toward the tip, and the portion contacting the inner surface of the molding die is expanded. It will not expand and move further. When the pressurization is continued, next, the non-contact portion with the adjacent inner surface of the molding die expands, comes into contact with the inner surface of the molding die, and the expansion is stopped. By repeating this in sequence, the expansion proceeds toward the tip of the pressure bag, and the bottomed portion of the tip of the pressure bag moves toward the tip in the molding die.

Finally, when the tip projection of the pressure bag expands and comes into contact with the tip of the inner surface of the molding die, the expansion of the pressure bag stops and the movement of the tip projection also stops.

According to the above analysis, as shown in FIG. 4, when fluid pressure is applied to the pressure bag (1), the thin film portion (3) of the pressure bag (1) expands,
Rupture (4) occurs when the extension limit is exceeded. This burst
(4) is likely to occur because there is a large space between the tip (5) of the thermosetting resin sheet (6) wound around the outer periphery of the pressure bag (1) and the gap between the mold (2). Becomes

If the expansion stops before the limit of expansion, no rupture occurs. This expansion stops when the thin portion (3) of the pressure bag (1) expands and hits against the thermosetting resin sheet (6), the thermosetting resin sheet (6). Indicates a state where expansion of the thin film portion (3) is impossible. In this state, even if pressure is applied to the inside of the pressure bag (1), expansion of the pressure bag (1) is blocked by the molding die (2), so that the pressure bag (1) does not deform and does not burst.

From the above, the mechanism of rupture of the side surface of the pressure bag (1) is considered as follows. That is, the pressure bag is attached to the tip portion (5) of the thermosetting resin sheet (6) wrapped around the outer circumference of the pressure bag (1).
If there is a portion with a large film thickness in (1), the portion adjacent to this portion with a large film thickness expands, and if the difference in film thickness is large, only the portion with a small film thickness (3) It expands and ruptures when the extension limit is exceeded. This state is shown in FIG. Then, when the expansion of the thin portion (3) reaches a limit before the limit of extension, that is, when it hits against the thermosetting resin sheet (6), the thermosetting resin sheet
(6) prevents expansion and does not burst when expansion stops.

In view of the mechanism of rupture occurring on the side surface of the pressure bag (1) described above, the pressure bag
The rupture of the tip protrusion (10) of (1) is considered to occur due to the following mechanism.

The pressure bag (1) expands in sequence from the direction of introduction of the pressurized fluid, and this expansion reaches the bottomed part (7) at the tip of the pressure bag (1), and the expansion and the bottomed part (7).
The movement is stopped in the mold (2). When there is a space between the tip of the pressure bag (1) and the tip (8) of the inner surface of the molding die (2), expansion and movement of the tip may occur even when the pressure reaches 10 kg / m ^2. Absent. This is because the tensile strength of the rubber is larger than the pressure for expanding, that is, the force of 10 kg / m ² .

In this state, when the temperature of the tip protruding portion (10) of the pressure bag (1) reaches the temperature at which the plasticization of the rubber starts due to the heating of the molding die, for example, 150 ° C. or more,
The plasticization of the pressure bag (1) begins, the tensile strength becomes small, and rupture occurs. The rupture at this time is not a burst due to exceeding the elastic limit of rubber as in the rupture of the side surface, but is caused by buckling or displacement occurring in the plasticized substance. This can also be said from the fact that when the broken parts of the ruptured product of the tip protruding portion (10) are analyzed, it cannot be seen after it has expanded to the elastic limit and burst.

In order to prevent the pressure bag (1) from bursting at the tip projection (10), the bottomed portion (7) of the tip projection (10) of the pressure bag (1) is molded before plasticization begins. It may be brought into contact with the tip (8) of the inner surface of (2). The space between the bottomed portion (7) of the tip protruding portion (10) of the pressure bag (1) and the tip protruding portion (10) of the inner surface tip (8) of the molding die (2) is defined as the extra extension length ( 11).

As described above, in order to prevent the tip protrusion (10) of the pressure bag (1) from rupturing, the bottomed portion (7) of the tip protrusion (10) is fixed to the molding die (2) before plasticization begins. It is sufficient to bring the tip of the inner surface (8) of () into contact with the tip of the pressure bag (1) and the inner tip (8) of the molding die (2) theoretically. 11) so as not to form
The pressure bag (1) may be placed in the molding die (2).

However, in reality, this extra length
(11) is not formed, or an extra elongation length of 4 mm or less that does not cause rupture, which has been found by the inventors' experiments.
(11) is practically difficult.

If the relationship between the pressure bag (1) and the molding die is designed so that the extra stretch length (11) does not occur at all, the internal dimensions of the molding die should be smaller than the internal dimensions of the molding die due to manufacturing errors. Tip protrusion of pressure bag (1)
If the dimension of (10) becomes long, the pressure bag
Pressure bag when (1) is inserted into the mold
When the mold (2) is deformed and the mold (2) is a split mold, a part of the pressure bag (2) is sandwiched between the abutting molds (2) and causes a rupture.

In the pressure bag (1), a core metal (not shown) is inserted inside when the thermosetting resin sheet (6) is wound around the pressure bag (1).
In many cases, the core metal is inserted in a direction in which the pressure bag (1) is slightly stretched when the core metal is inserted. Since the thermosetting resin sheet (6) is wrapped around the outer periphery of the pressure bag (1) in a stretched state, the stretched state is maintained when the core metal is pulled out and inserted into the molding die (2). ing. Then, by heating the mold (2), the pressure bag (1) contracts to the state before being stretched by the core metal. Due to this heat shrinkage, the bottomed part (7) of the pressure bag (1) and the tip of the inner surface of the molding die
An air gap is generated between (8) and the extra elongation length (11), or the existing extra elongation length (11) is increased.

When the pressure bag (1) having the thermosetting resin sheet (6) wound around the outer periphery thereof is set in the molding die (2), a plurality of pressure bags (1) are molded.
It is common to set in (2) at the same time and perform molding.
In that case, if the setting is done slowly, the thermosetting of the thermosetting resin sheet (6) set earlier will proceed before the pressurization, so it is necessary to set it quickly, and the extra elongation It is practically difficult to accurately set a plurality of pressure bags (1) so that (11) becomes zero or becomes 4 mm or less.

The present invention, as described above, includes a pressure bag.
Between the tip of (1) and the tip of the inner surface (8) of the molding die (2), the extra length of extension (11), the inner peripheral surface of the molding die (2) and the outer peripheral surface of the pressure bag (1). Due to the presence of voids or the like generated between the pressure bag (1) and the mold (2), only a part of the pressure bag (1) is inflated to prevent rupture. And a thermosetting resin sheet wrapped around the outer periphery
It is intended to surely press and compress (6) on the inner surface of the molding die (2) so that the thermosetting resin sheet (6) can be surely pressure-molded.

[0024]

In order to solve the above-mentioned problems, the present invention introduces a pressure fluid into the mold with a thermosetting resin sheet wound around the outer periphery and inserted and arranged in a molding die. In a pressure bag for internal pressure molding, in which the thermosetting resin sheet is pressed and brought into close contact with the inner surface of the molding die by pressure expansion, it corresponds to the inside of the tip of the thermosetting resin sheet wrapped around the outer periphery. On the outer periphery of the part, a stopper part with a thicker film thickness is formed, and the film thickness is gradually increased from this stopper part to the bottom part of the tip protruding part protruding outward of the thermosetting resin sheet. It is formed.

[0025]

EXAMPLE An example of the present invention will be described below. (1) is a pressure bag, which is made of a material such as natural rubber and whose diameter and length are determined according to the object to be pressure-molded. You can do it. For example, it can be used to form fishing rods, golf shafts, tennis racket frames, ski poles, and other general tubular bodies. However, depending on the required length, it is possible to determine the length and diameter. it can.

The pressure bag (1) has an opening at one end thereof, into which an introduction nozzle (12) for introducing a fluid such as air, nitrogen gas or liquid can be attached.
(13). Further, the tip of the tip protruding portion (10) is formed to have a bottom to form a bottomed portion (7), and the pressure bag (1) is formed to be inflatable by the fluid introduced from the opening (13). ing.

The pressure bag (1) is a thermosetting resin sheet in which reinforcing fibers and thermosetting resin are mixed.
(6), a thermosetting resin sheet (6) in which reinforcing fibers are pre-prepared with a thermosetting resin, a thermosetting resin sheet (6) in which reinforcing fibers and a thermosetting resin are laminated in a sheet shape, and the like are wound. However, on the outer periphery of the tip protruding portion (10), a stopper portion (14) having a thick film thickness and protruding to the outer periphery is formed.

When the thermosetting resin sheet (6) is wound around the outer periphery of the pressure bag (1), the stopper portion (14) is disposed inside the thermosetting resin sheet (6) in the direction of the tip. Is formed. Then, the tip end protruding portion (10) of the pressure bag (1) protrudes outward from the tip end portion of the thermoplastic resin sheet (6).

When the thermosetting resin sheet (6) is wound around the outer circumference of the pressure bag (1), the protrusion of the tip protruding portion (10) extends to which part of the pressure bag (1) the thermosetting resin sheet (6). It is necessary to project the tip projecting portion (10) because it is visually determined whether or not () is wound.

Then, as shown in FIG. 1, the tip protruding portion (10) is inserted and set in the molding die (2).
Than the pressing part of the thermosetting resin sheet (6) of the molding die (2)
It is to be inserted into the small tip diameter portion (15) having a reduced diameter. And, in the normal insertion state, the tip small diameter portion (1
In 5), the bottomed part of the tip of the pressure bag (1)
An extra length of extension (11) is formed between (7) and the inner surface tip (8) of the tip small diameter portion (15).

Further, the pressure bag (1) is formed such that the film thickness is gradually increased from the stopper portion (14) to the bottomed portion (7) arranged at the tip of the tip protruding portion (10) to form a stopper. Tip protrusion (10) continuous with part (14)
Is formed thin, and the thickness of the tip protruding portion (10) is formed thicker in the direction of the bottomed portion (7).

In order to press-mold the target product using the pressure bag (1) having the above-mentioned structure, first insert a core into the pressure bag (1). . Insertion of the core metal is carried out from the open mouth (13) to the bottom portion (7), if may be preferably carried out so as not to or to extend the pressure bag (1). However, in reality, if the core metal is securely inserted into the pressure bag (1), the core metal will be elongated to some extent.

Then, the pressure bag (1) in which the core metal is inserted is a thermosetting resin sheet (6) in which a sheet-shaped thermosetting resin is laminated on a carbon fiber sheet, or carbon fibers are pre-pregged with the thermosetting resin. The thermosetting resin sheet (6) is wrapped around the outer circumference of the pressure bag (1) by a winding machine to cover it. This thermosetting resin sheet (6) is wrapped around the pressure bag (1)
Starting from the direction of the bottomed portion (7) of the opening (13), the process is performed until the stopper (14) is covered.

The pressure bag (1) has a tip portion (10) extending from the tip portion (5) of the thermosetting resin sheet (6).
Is projected. In this state, the core metal is removed from the pressure bag (1), and then the introduction nozzle (12) is attached to the opening (13) of the pressure bag (1) as shown in FIG. The introduction nozzle (12) can penetrate the introduction passage (17) for introducing a liquid such as air, nitrogen gas and water in the central axial direction, and can introduce a pressurized fluid into the pressure bag (1). Is formed.

Next, the introduction nozzle (12) is mounted, and the pressure bag (1) having the thermosetting resin sheet (6) wound around the outer periphery is mounted in the molding die (2). This mold (2)
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 parts as necessary. Also, the mold (2)
Is a packing for pressing and fixing the outer periphery of the opening (13) of the pressure bag (1) to the outer periphery of the introduction nozzle (12).
(18) is formed. Further, adjacent to the packing (18), an annular collar (21) fitted into the outer peripheral annular groove (20) of the introduction nozzle (12) is projected to stably fix the introduction nozzle (12).

Next, after the mold (2) is clamped, a pressurized fluid is introduced from the introduction nozzle (12) to inflate the pressure bag (1). In this expansion, the thermosetting resin sheet (6) is strongly pressed from the inside by the pressure bag (1) against the inner surface of the molding die (2), and is densely thermoset.

When the thermosetting resin sheet (6) is pressed, the pressure bag (1) is inflated, and the expansion proceeds from the tip portion (5) to the tip of the thermosetting resin sheet (6). Protrusion
In (10), the tip protruding part from the stopper part (14)
The film thickness of the pressure bag (1) is sequentially increased from the bottom part (7) through the (10).

In the pressure bag (1) formed of a material having rubber elasticity such as natural rubber, when internal pressure is applied, generally, as described above, expansion starts from the thin portion. Become. Therefore, at the tip protruding portion (10) protruding from the tip portion (5) of the thermosetting resin sheet (6), the stopper portion covered with the thermosetting resin sheet (6)
Since the tip protruding portion (10) continuous with (14) is the thinnest, the bottomed portion (7) with a large film thickness expands sequentially from this portion.
The expansion moves in the direction.

Then, the bottomed portion (7) of the tip projecting portion (10) of the pressure bag (1) moves in position according to this expansion, and the inner surface tip (in the tip small diameter portion (15) of the molding die (2) ( 8) Move sequentially in the direction. And in this expansion process,
The bottomed portion (7) completes its expansion by abutting its tip against the inner surface tip (8) of the molding die (2).

The protruding end of the pressure bag (1)
Since the film thickness of (10) gradually increases from the stopper portion (14) toward the bottomed portion (7), the expansion due to the internal pressure applied to the pressure bag (1) does not occur.
From (14) to the bottomed part (7) direction, they sequentially occur.

Therefore, as in the conventional case, the expansion is caused by the protruding end portion.
(10) is generated in the bottomed part (7) direction first, and the movement is fixed, which hinders the movement of the bottomed part (7) toward the inner surface tip (8),
The movement of the bottomed part (7) is not stopped while leaving the space of the extra length (11). Extra length as before
When the movement of the bottomed part (7) is stopped while leaving (11), the temperature inside the mold (2) rises, and a temperature exceeding 150 ° C. is applied to the pressure bag (1). At times, plasticization occurs at the tip protrusion (10) of the pressure bag (1). Then, the bottomed portion (7) or the protruding end portion
In (10), buckling or displacement due to plasticization causes rupture.

However, in the present invention, the tip protrusion (1
0) will be expanded in order from the stopper direction, so there is a bottom part (7) in the small tip diameter part (15) of the molding die (2).
The movement of the bag is not blocked, and the pressure bag (1)
Is expanded from the stopper part (14) direction to the bottomed part (7) direction in order to expand the bottomed part (7) to the mold.
It is possible to move to the tip (8) of the inner surface of (2) and press it.

When the bottomed portion (7) hits the inner surface tip (8), even if abnormal pressure is applied to the inner surface of the pressure bag (1), the tip protruding portion (10) and the bottomed portion (8) The outer circumference of (7) is held against the inner surface of the molding die (2), so that no rupture or the like occurs. Then, in the state where the bottomed portion (7) hits the tip (8) of the inner surface of the molding die (2), the thermosetting resin sheet (6) is expanded by the expansion of the pressure bag (1). , Pressed against the inner surface of the mold (2) to densify the composition, and
Good molding can be performed.

Then, after the thermosetting resin sheet (6) is pressed by the pressure bag (1) for a certain period of time, the introduction of the pressurized fluid from the introduction nozzle (12) is stopped, and the pressure bag ( Stop applying pressure to 1). Next, the molding die (2) is separated into an upper die, a lower die or a plurality of divided dies, and a molded product formed of the thermosetting resin sheet (6) is taken out. Then, by removing the introduction nozzle (12) from the molded product and then removing the pressure bag (1), a molded product of the thermosetting resin sheet (6) can be obtained.

The stopper portion (14) of the pressure bag (1) described above is a thermosetting resin sheet.
It engages and engages with the inner surface of (6). In this way, the stopper portion (14) bites into and engages with the inner surface of the thermosetting resin sheet (6), so that the thermosetting resin sheet
When winding (6) around the outer circumference of the pressure bag (1), a core metal was inserted into the pressure bag (1). At the time of insertion, when the pressure bag (1) is stretched by the core metal, that is, when the core metal hits the bottomed part (7) and the entire length of the pressure bag (1) is extended, it is thermoset. When the resin sheet (6) is wrapped around the pressure bag (1), the pressure bag
In (1), the expanded state is maintained.

Even after the core metal is pulled out from the pressure bag (1), the expanded state of the pressure bag (1) is often fixed at room temperature. However, using this pressure bag (1) with the mold (2)
When inserted and heated, the pressure bag (1) restores the expanded state to the original state due to the effect of heating. Then, due to the restoration, the interval between the bottomed portion (7) and the tip of the inner surface (8) of the molding die (2) is expanded, and the extension length (11) is increased.

As described above, increasing the extra length of extension (11) causes rupture during the inflation process of the pressure bag (1), which is not preferable. However, if the stopper portion (14) is formed on the outer periphery of the pressure bag (1) and bites into and engages with the inner surface of the thermosetting resin sheet (6) as in the present invention, the pressure bag (1) is In the thermosetting resin sheet (6), even if an expansion portion fixed by the stopper portion (14) and expanded by the core metal is restored, the restoration to the original length is prevented.

Therefore, the bottomed portion (7) and the inner surface tip (8) in the state where the pressure bag (1) is mounted in the molding die (2) without increasing the extra stretch length (11). It is possible to substantially maintain the distance between the two and to prevent the extra length of extension (11) from being greatly expanded.

[0049]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, a pressure bag for winding a thermosetting resin sheet around the outer periphery, inserting the thermosetting resin sheet in a molding die, and press-molding the thermosetting resin sheet is provided. In this case, it is possible to prevent the rupture caused by various conditions and to reliably pressurize the thermosetting resin sheet without rupture.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a tip protruding portion showing a state in which a thermosetting resin sheet is wound around the outer circumference of a pressure bag and mounted in a molding die.

FIG. 2 is a schematic cross-sectional view showing a state in which a thermosetting resin sheet is wound around the outer periphery of a pressure bag and mounted in a molding die.

FIG. 3 is a sectional view of a pressure bag.

FIG. 4 is a cross-sectional view showing a state in which a side surface of the pressure bag is ruptured.

[Explanation of symbols] 1 pressure bag 2 molding die 5 tip portion 6 thermosetting resin sheet 7 bottomed portion 10 tip protruding portion 14 stopper portion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29L 23:00 31:52

Claims (1)

[Claims] 1. A thermosetting resin sheet is wound on the outer periphery and inserted and arranged in a molding die, and a pressure fluid is introduced into the molding die to expand the pressure, whereby the thermosetting resin sheet is formed on the inner surface of the molding die. In a pressure bag for internal pressure molding that presses and makes close contact with the inner surface of the thermosetting resin sheet that is wound around the outer periphery, a stopper portion that is thickened and protrudes is formed on the outer periphery of the portion that corresponds to the inside of the tip of the thermosetting resin sheet. As it forms
An internal pressure forming pressure bag characterized in that the film thickness is sequentially increased from the stopper portion to the bottom portion of the tip protruding portion protruding outward of the thermosetting resin sheet.