JP2009028939A - Rtm molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an RTM molding method which can greatly simplify the structure of a mold, to reduce a processing cost and can efficiently and promptly form even an FRP molding having an undercut shape. <P>SOLUTION: In the RTM molding method, a reinforcing fiber substrate is arranged in the cavity part of the mold composed of a plurality of molds including first and second molds arranged opposite to each other, after mold clamping, when the FRP molding is molded by injecting a resin, an intermediate member which is formed in advance in a shape to parallel the shape of the molding is set between the first mold and the second mold, a pressurized medium is filled between the intermediate member and the second mold, the reinforcing fiber substrate is arranged between the intermediate member and the first mold, and the resin is injected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an RTM (Resin Transfer Molding) molding method for an FRP (fiber reinforced resin) molded product, and more particularly to an RTM molding method that is suitable when an undercut portion needs to be provided in a molding die.

  An RTM molding method is known in which a reinforcing fiber base material is disposed in a cavity of a molding die composed of a plurality of molds, and after mold clamping, a resin is injected to mold an FRP molded product (for example, Patent Document 1). . In such an RTM molding method, when the molding die is a double-sided die comprising, for example, a lower die and an upper die, if there is an undercut shape in the FRP molded product to be molded, it is usually difficult to mold to the undercut shape. . That is, although it is necessary to provide an undercut part also in a shaping | molding die, if there is an undercut part, a type | mold will not close as it is. Therefore, in such a case, any part of the double-sided mold is split (for example, a structure having a plurality of holders (slide cores)), and even if there is an undercut, the mold is clamped. In addition, it is possible to demold the molded product after molding.

  For example, as shown in FIG. 3, when a preform 103 in which a reinforcing fiber base is preliminarily shaped into a predetermined shape is disposed in the cavity portion 102 of the lower mold 101, at least one split mold 104 and, in some cases, a plurality of split molds 104 are provided. After the upper die 106 having the undercut portion 105 is provided and temporarily closed, the split die 104 is slid to form a predetermined cavity shape, and in this state, the die is properly clamped and resin injection is started.

  However, in such a method, since it is necessary to provide at least one slidable split mold 104 in the mold and form it as a slide core, the mold becomes complicated and the processing cost increases. In particular, when a plurality of split molds 104 are provided, it is difficult to seal the cavity of the mold, and there is a problem that the sealing structure is complicated even if sealing is possible.

To solve the problem when using such a double-sided mold, use a single-sided mold, place a preform of reinforcing fiber base in the cavity of the single-sided mold, and use the bag material as a whole without using the upper mold. A method of covering and depressurizing the inside and injecting resin into the depressurized interior is known (for example, Patent Document 2). This method eliminates the need for an upper mold having an undercut portion as shown in FIG. 3, so that the entire mold structure can be simplified. However, this method can be applied to those in which resin injection is performed using vacuum pressure. However, since the pressure injection of the resin cannot be performed, there is a problem of the manufacturing efficiency of the molded product that the cycle time of the molding cycle becomes long.
WO2005 / 077632 U.S. Pat. No. 5,052,906

  Therefore, in view of the present situation as described above, the object of the present invention is to greatly simplify the structure of a molding die when molding an FRP molded product having an undercut shape, and to reduce the processing cost. It is an object of the present invention to provide an RTM molding method which can be easily sealed with a simple structure and can be molded efficiently and quickly even for an FRP molded product having an undercut shape.

  In order to solve the above-described problem, the RTM molding method according to the present invention includes arranging a reinforcing fiber base in a cavity portion of a molding die including a plurality of dies including a first die and a second die arranged to face each other. An RTM molding method for molding an FRP molded product by injecting resin after mold clamping, and an intermediate formed in advance between the first mold and the second mold in a shape along the shape of the molded product A member is provided, a pressurizing medium is filled between the intermediate member and the second mold, and a reinforcing fiber base material is disposed between the intermediate member and the first mold to inject the resin. It consists of the method.

  The first mold is, for example, a lower mold, and the second mold is, for example, an upper mold. Further, the intermediate member can be constituted by, for example, a relatively thin plate-like member, and any material can be used as long as it can withstand the temperature at the time of FRP molding, such as a plastic molded plate (for example, heat-shaped). Plate) and metal plates can be used. The intermediate member may be disposable for each molding, or can be repeatedly used for a predetermined number of moldings. Furthermore, as the pressurizing medium, it is possible to use a gas such as air, a liquid such as hot water or oil, and it is also possible to use a liquid fluid having a certain degree of viscosity.

  In such an RTM molding method, an intermediate member formed in advance along the shape of the molded product provided between the first mold and the second mold is formed between the intermediate member and the second mold. Since it is pressed to the first mold side by the pressurizing medium filled in between, the function equivalent to that of the upper mold having the inner surface shape along the shape of the molded product in the conventional structure can be exhibited. Therefore, the second die according to the present invention does not require a function like the upper die in the conventional structure, and simply keeps the filled pressurized medium in a sealed state at a predetermined pressure after the die clamping. It will suffice if the function is satisfied, and the structure of the second mold can be greatly simplified. In particular, even when an undercut shape is required for an FRP molded product, it is not necessary to make the second mold a complicated structure having an undercut portion, and a very simple structure can be used as the second mold. It is only necessary to form the intermediate member in a shape that follows the shape of the molded product. A reinforcing fiber base material is disposed between the intermediate member and the first mold, and resin is injected therein to form an FRP molded product. The intermediate member is formed in advance in a shape that conforms to the shape of the molded product. Since the first mold has a cavity portion that follows the shape of the molded product, it is formed between the lower mold and the upper mold in the conventional structure described above between the intermediate member and the first mold. A cavity equivalent to the cavity to be formed is formed. In this cavity, the surface on the first mold side is kept a rigid surface by the rigidity of the first mold itself, and on the intermediate member side, the pressurized medium filled between the intermediate member and the second mold Thus, even when the resin is injected between the intermediate member and the first mold, the intermediate member is kept in a predetermined shape by the pressing force of the pressurizing medium against the injected resin pressure. That is, the pressure of the injection resin and the pressing force of the pressurizing medium are substantially balanced, and the intermediate member is maintained in a predetermined shape. As a result, the FRP molded product is molded into a predetermined shape on both sides while having a simplified mold structure. This molding is also possible when resin is injected under pressure, so the cycle time of the molding cycle can be greatly reduced compared to when resin is injected using the vacuum pressure of the cavity. Become.

  In such an RTM molding method according to the present invention, at least one of the first and second molds may have at least one undercut portion in the mold opening direction. This method is particularly effective when an FRP molded product requires an undercut shape.

  Moreover, the pressurization medium with which it fills between an intermediate member and a 2nd type | mold should just be sealed between these intermediate members and a 2nd type | mold. For example, a sealing material extending along the outer periphery of the intermediate member may be disposed between the intermediate member and the second mold, and this portion may be sealed with the sealing material. Since the structure of the second mold can be greatly simplified by the presence of the intermediate member, the structure for sealing during mold clamping during this time is also greatly simplified.

  The pressure of the pressure medium can be set to a pressure of 0.05 to 1 MPa, for example. In other words, it is sufficient to consider the balance with the resin injection pressure. However, the pressure of the pressurizing medium is not limited to the above range when the pressure is lower or higher than the resin injection pressure. Also, when injecting resin, pressurizing medium pressure is lower than resin injecting pressure, and after the resin fills the mold, pressurizing medium pressure is increased above resin pressure to shorten molding time. May be.

  The thickness of the intermediate member is preferably in the range of 0.1 to 5 mm. Since the pressure of the pressurizing medium applied to each surface of the intermediate member and the pressure of the injected resin are substantially balanced as described above, the intermediate member itself is not required to have great rigidity, and a plate-like member having an appropriate thickness can be obtained. It only has to be formed. The actual thickness may be appropriately set within the above range, taking into consideration the area of the molded product, the presence or absence of grooves on each surface, the pressure of the pressure medium, the resin injection pressure, and the like.

  A structure in which a groove is formed on at least one surface of the intermediate member can also be employed. In particular, if a groove is formed on the surface of the first member side of the intermediate member, the groove can function as a resin flow path, so that good diffusion of the injected resin and uniform and good impregnation into the reinforcing fiber substrate can be achieved. You can be encouraged. If a groove is formed on the surface on the second mold side of the intermediate member, the groove can promote more uniform dispersion when the pressurized medium is a liquid or the like, for example.

  As described above, the RTM molding method according to the present invention is an effective method particularly when an undercut shape is required for an FRP molded product, but if necessary, a split is applied to the undercut portion of the mold. It can also be provided. If a split is provided, it is easy to remove the molded product from the mold.

  Thus, according to the RTM molding method according to the present invention, the structure of the molding die particularly when molding an FRP molded product having an undercut shape can be greatly simplified, and the processing cost can be greatly reduced. In addition, the seal structure at the time of mold clamping can be greatly simplified. Therefore, a desired FRP molded product, particularly an FRP molded product having an undercut shape, can be easily and efficiently molded using a mold having a simple structure. Further, since the resin can be injected under pressure basically, the tact time of the molding cycle can be greatly shortened by adopting appropriate injection conditions.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows how the RTM molding method according to one embodiment of the present invention is carried out. In FIG. 1, 1 indicates a lower mold as a first mold disposed opposite to each other in the present invention, and 2 indicates an upper mold as a second mold. In FIG. 1, only the first mold 1 and the second mold 2 are shown as a plurality of molds constituting the mold, but in the present invention, the mold may be composed of three or more molds. is there. Between the 1st type | mold 1 and the 2nd type | mold 2, the intermediate member 3 which consists of a plate-shaped member with a thickness of 0.1-5 mm previously formed in the shape along the shape of a FRP molded product, for example is arrange | positioned Is done. A space between the intermediate member 3 and the second mold 2 is filled with a pressure medium 4 such as air or hot water at a pressure of 0.05 to 1 MPa, for example. The pressurized medium 4 to be filled is sealed by a sealing material 5 arranged between the intermediate member 3 and the second mold 2, and the pressure of the filled pressurized medium 4 is maintained at the desired pressure. . On the other hand, between the intermediate member 3 and the first mold 1, a reinforcing fiber base preform 6 is disposed, and the preform 6 is disposed in the cavity portion 7 of the first mold 1. In a state where the pressurizing medium 4 is filled between the intermediate member 3 and the second mold 2 or together with the filling, the inside of the cavity portion 7 of the first mold 1, that is, the intermediate member 3 and the first mold 1. In between, resin 8 used as a matrix of FRP is injected under pressure. The injected resin 8 is diffused between the intermediate member 3 and the first mold 1 and impregnated in a reinforcing fiber base formed as a preform 6, and the injected resin is cured and predetermined FRP molding is performed. The product is molded.

  In the illustrated example, the FRP molded product to be molded has one undercut shape portion, and the intermediate member 3 portion corresponding thereto is also formed in the undercut portion 9, and the lower die 1 corresponding thereto is further formed. An undercut portion is also formed in the portion. This embodiment shows a case where the FRP molded product can be removed from the lower die 1 even when the lower die 1 has such an undercut portion (when it can be removed obliquely in the upper left of the figure). The undercut shape portion of the lower mold 1 shows an aspect configured as a part of the lower mold 1 itself.

  In the molding of an FRP molded product, the intermediate member 3 formed in advance on one surface of the molded product is pressed from the one surface side to the first mold 1 side by the filled pressurizing medium 4, and the intermediate member 3 The surface 8, that is, the reinforcing fiber base preform 6 disposed between the intermediate member 3 and the first mold 1 is pressurized and injected with a resin 8, and this portion of the first mold One cavity portion 7 is filled and impregnated in the reinforcing fiber base material. A downward pressing force of FIG. 1 against the intermediate member 3 by the pressurizing medium 4 filled between the intermediate member 3 and the second die 2 and the intermediate member 3 and the first die 1 are injected. The pressure of the filled resin 8 is substantially balanced and the intervening intermediate member 3 is kept in its original preformed shape. Without forming an undercut part in the second mold 2 or providing a split mold corresponding thereto, simply forming the intermediate member 3 made of a thin plate member into a shape with an undercut part, A desired FRP molded product having an undercut shape portion can be molded, and the structure of the mold, particularly the structure of the second mold 2 is greatly simplified, and the mold processing cost is greatly reduced. Further, at the time of demolding, the second mold 2 only needs to be opened upward, and it is only necessary to remove the intermediate member 3 from the FRP molded product after demolding or at the same time as demolding. Therefore, efficient molding becomes possible.

  Further, since the pressing force by the pressurizing medium 4 filled to keep the intermediate member 3 in a predetermined shape and the pressure of the injection resin 8 are balanced, the resin 8 can basically be injected under pressure. . In the case of pressurized injection, compared to reduced pressure injection, virtually any injection rate can be set, and the injection time can be easily controlled to the desired time, allowing the tact time of the molding cycle to be greatly reduced. Become.

  FIG. 2 shows how the RTM molding method according to another embodiment of the present invention is carried out. This embodiment assumes the case where it is difficult to remove the FRP molded product from the first mold 1 with the form of the embodiment shown in FIG. 1. Compared to the form shown in FIG. For example, a slidable split 11 is provided for the undercut portion of the first mold 1. Other configurations are substantially the same as those shown in FIG. 1, and therefore, the same reference numerals as those shown in FIG.

  In this embodiment, by providing the slidable slit 11 as necessary as described above, it is easy to remove the mold even in the case of molding a molded product having an undercut portion that is difficult to remove. become able to. However, in this case as well, the structure of the second mold 2 is greatly simplified, the mold processing cost is greatly reduced, and the mold opening of the second mold 2 can be performed very easily. Further, the pressure injection of the resin 8 can greatly reduce the cycle time of the molding cycle.

  In the present invention, FRP (fiber reinforced resin) refers to a resin reinforced with reinforcing fibers, and as reinforcing fibers, in addition to carbon fibers, for example, inorganic fibers such as glass fibers, Kevlar fibers, polyethylene fibers, It is also possible to use reinforcing fibers made of organic fibers such as polyamide fibers. Carbon fiber is particularly preferable from the viewpoint of easy control of the rigidity and the like of the molded product. Examples of the FRP matrix resin include thermosetting resins such as epoxy resins, unsaturated polyester resins, vinyl ester resins, and phenol resins, and polyamide resins, polyolefin resins, dicyclopentadiene resins, polyurethane resins, and the like. These thermoplastic resins can also be used.

  The RTM molding method according to the present invention can be applied to any RTM molding in which an FRP molded product is molded using a reinforcing fiber substrate, and is particularly suitable when the FRP molded product has an undercut shape.

It is a schematic sectional drawing which shows the mode of implementation of the RTM shaping | molding method which concerns on one embodiment of this invention. It is a schematic sectional drawing which shows the mode of implementation of the RTM shaping | molding method which concerns on another embodiment of this invention. It is a schematic sectional drawing which shows the mode of implementation of the conventional RTM shaping | molding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower mold | type 2 as 1st type | mold 2 Upper mold | type 3 as 2nd type | mold 3 Intermediate member 4 Pressurizing medium 5 Sealing material 6 Preform 7 of a reinforced fiber base 1 Cavity part 8 of 1st type | mold Undercut part 11

Claims (7)

  An RTM that forms a FRP molded product by injecting a resin after placing a reinforcing fiber base in a cavity portion of a molding die including a plurality of dies including a first die and a second die arranged to face each other. In the molding method, an intermediate member formed in advance in a shape corresponding to the shape of the molded product is provided between the first die and the second die, and the intermediate member is added between the intermediate die and the second die. An RTM molding method comprising filling a pressure medium, injecting a resin with a reinforcing fiber base disposed between the intermediate member and the first mold.   The RTM molding method according to claim 1, wherein at least one of the first and second molds has at least one undercut portion in the mold opening direction.   The RTM molding method according to claim 1, wherein a pressurized medium to be filled is sealed between the intermediate member and the second mold.   The RTM molding method according to claim 1, wherein the intermediate member is pressurized with a pressure of 0.05 to 1 MPa with the pressurizing medium.   The RTM molding method according to claim 1, wherein the intermediate member has a thickness in a range of 0.1 to 5 mm.   The RTM molding method according to claim 1, wherein a groove is formed on at least one surface of the intermediate member.   The RTM shaping | molding method in any one of Claims 2-6 which provides a split with respect to the said undercut part.

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