JP4507343B2 - Manufacturing method of base material for FRP molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a preform manufacturing method used for manufacturing FRP by autoclave molding, RTM (resin transfer molding), or the like, and a bag-like material used for manufacturing the preform.
[0002]
[Prior art]
For the production of FRP, a preform in which reinforcing fibers are processed into a shape substantially close to the final shape of interest is used. For example, a prepreg in autoclave molding is a sheet-like preform in which a reinforcing fiber is impregnated with an uncured resin. This prepreg is cut into a predetermined shape and laminated along a mold, and then in an autoclave. The resin is cured to form FRP. In autoclave molding, an automatic machine called an auto layup machine has been developed when the mold is a flat plate, but automation is difficult in the case of a three-dimensional complicated shape, such as a hand and a spatula. Lamination (hand lay-up) is performed with tools, and productivity is extremely low.
[0003]
On the other hand, in RTM molding, a preform formed by reinforcing fibers such as woven fabric, braid, mat, etc., which is not impregnated with resin, into a predetermined shape inside or outside the mold After the preform is loaded into the mold, the resin is injected into the mold and cured to obtain FRP. For example, in Japanese Patent Publication No. 8-509921, a base material provided with a thermoplastic resin adhesive is applied to the base material under pressure in a mold that compresses the base material into a predetermined shape and thickness. A method for producing a preform by heating the agent is disclosed.
[0004]
However, when a two-dimensional textile substrate is clamped with a double-sided mold having a three-dimensional shape, the substrate needs to move not only in the clamping direction of the mold but also perpendicularly to match the material balance. There are cracks and cracks when the movement is insufficient. There is a problem that cracks are more likely to occur as the shape of the mold becomes more complicated with unevenness.
[0005]
On the other hand, as disclosed in Japanese Patent Laid-Open No. 4-97828, there is also disclosed a method of pressing a rod-shaped body called a movable plug against a base material and shaping the base material into a predetermined mold shape. In this method, since the rod has a finite diameter, the base material cannot be pressed at the corner portion of the mold having a small rounding radius, and the material balance is not matched, and cracks and tarmi occur.
[0006]
Although it can be improved to some extent by reducing the diameter of the bar and increasing the number of bars, there is a problem of penetrating the fabric (eyes) if the diameter is reduced, and the number of bars is increased to a considerable number. Otherwise, the pressed substrate will be stretched because it pressed other parts, and it will be in the state of hitting the mole, so it will not be possible to obtain a preform with the desired shape, and this method has application limits .
[0007]
In order to improve the production efficiency of FRP, other than the above, a preform production technique and a base material automatic shaping technique are desired.
[0008]
[Problems to be solved by the invention]
The problem to be solved by the present invention is the problem of preform production comprising the above-described prepreg and dry substrate, in particular, to easily and stably shape the reinforcing fiber substrate into a complex shape, An object of the present invention is to provide a method for producing a base material for FRP molding that enables simplification and automation of a preform shaping process indispensable for high production efficiency of FRP molding.
[0009]
In order to achieve the above object, the present invention provides a manufacturing method having the following configuration. That is, a bag-like product (B) which is composed of granular materials having a specific gravity of 2.2 to 7.9 and contains a fluid (A) having fluidity , and a mold having a desired shaping shape ( In the method of manufacturing a base material for FRP molding in which a base material (D) is arranged between C) and A and B flow , B spreads along D, and D is shaped into a C shape. is there.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The manufacturing method of this invention is demonstrated in detail based on one embodiment shown in FIGS. A base material (D) 4 is set between a bag-like article (B) 2 having therein a heavy article (A) 1 rich in fluidity and a mold (C) 3 having a desired shaping shape, For example, D is sandwiched between B and C by shaping A so that lava flows, and the shape of C is shaped.
[0011]
First, as a heavy article (A), the bag-like article (B) is filled. A is a fluid such as water or oil, viscoelastic material such as clay or resin, granular material such as ceramic or metal, powder such as sand, etc. What to do can be applied. As the bag-like material (B), a material that is flexible, deformable, and / or stretchable so that a heavy material can flow while inside the bag can be applied, and is made of a polymer such as rubber or plastic. It is preferable. The heavy article (A) can flow while inflating or moving the bag-like article (B).
[0012]
The mold (C) is made of metal, wood, FRP, or the like, and has the same two-dimensional or three-dimensional shape as the shape of the target preform. Between the main mold (C) and the bag-shaped object (B), the base material (D) serving as the reinforcing fiber of the FRP is set in a state where it is not fixed, or in a state where it is partially fixed to the mold.
[0013]
As shown in FIGS. 2 to 4, the bag-like object (B) is pressed along the mold (C) from the main state of FIG. When B) is made to conform to the surface shape of the mold (C), the base material (D) is deformed between the bag and the mold and is the same two-dimensional or three-dimensional as the target mold (C). The preform has a shape.
[0014]
The faster the flow of heavy objects, the better the productivity, but if it is too early, the shape of the mold is complicated, and if there are large dents or protrusions, the bag stretches at the corner and Since the shape may not be the desired shape, the moving speed of heavy objects is controlled by the material of the bag-like material, the inclination of the mold, etc., or the deformation of the bag-like object is controlled by a spatula or plate-like object It is effective to provide a guide on the outside of the bag such as a rod-shaped object for adjustment. In particular, a preferable fluidity control method includes adjusting the internal pressure of the bag-like material. That is, if the inside of the bag-like material is evacuated, the fluidity can be eliminated. The fluidity can be adjusted with an appropriate internal pressure. The reason why this method is most preferable is that when the bag-like product is removed from the mold, the internal pressure of the bag-like product is evacuated, so that no force is applied to the preformed substrate, that is, the substrate is repelled. This is because the bag-like material can be removed without deformation. In addition, since the bag-like material is an elastic material such as thin rubber, it is possible to flow in a direction opposite to the direction once flowed (changeable) due to a change in internal pressure.
[0015]
The heavy material is preferably a liquid with good fluidity, but is preferably mercury or the like having a large specific gravity that can overcome the deformation resistance of the base material and flow, or a metal particulate material. Furthermore, a magnetic material is preferable because it can apply a magnetic force to a difficult-to-flow portion such as a corner portion of a mold to guide the particles to the tip of the corner portion and improve the accuracy of shaping.
[0016]
In the case of particulate matter, if the grain is larger than the round radius of the corner, the base material will not be shaped to the shape of the corner, so it should be in the shape of the mold, that is, the particle size should be less than the minimum corner radius is important. Specifically, it is preferable that the particles have an average radius of 5 mm or less because they can flow along a considerable mold shape.
[0017]
The diameter of the particles can be obtained by averaging the data measured to the first decimal place with the size in the arbitrary direction of 10 arbitrarily extracted particles in mm units using a caliper or a micrometer. In the case of a small powder that is difficult to measure with a caliper or a micrometer, it can be measured by the sedimentation mass method described in JIS Z8822.
[0018]
Normally, when a bag-like material containing spherical particles is flowed on a flat plate with no inclination, the bag-like material has a tendency to flow in a circular shape. Therefore, the thickness of the bag-like material is changed according to the shape of the die. A uniform thickness is also preferred. It is preferable to reduce the thickness of the bag-like material in the direction in which it is desired to flow faster because the resistance to the flow of the heavy material is small and the bag-like material will flow more quickly in the direction of thinner thickness.
[0019]
In addition to the particulate or powdery fluid, the bag-like material may be additionally filled with a gas such as air or inert gas or a liquid such as water. By performing additional filling, the particulate matter wraps around the corner portion where the particulate matter is difficult to wrap around, or gas or liquid wraps around, making it possible to manufacture a preform with higher accuracy. Further, it is preferable to pressurize the gas or liquid to cause the particulate matter, gas or liquid to flow in more detail in order to improve the accuracy of the preform.
[0020]
The bag-like material does not need to be spherical or cylindrical, and it is more preferable if the bag-like material is designed to have an irregular shape that is manufactured by joining in accordance with the mold.
[0021]
Moreover, the bag-like material does not necessarily need to be an elastic material, and may be provided with “sag” instead of expansion and contraction. In other words, when the vacuum inside the bag is released on the mold as a bag-like material with a bag of wrinkles etc., the heavy material will flow almost without resistance even though the bag is not stretchable. Can do.
[0022]
A heavy object is selected depending on the deformation resistance of the base material, the number of laminated layers, etc., but the specific gravity is preferably in the range of 0.8-15. If it is less than 0.8, it may be insufficient to deform a base material having a large deformation resistance such as a woven fabric, and if it exceeds 15, a bag-like material may be torn.
[0023]
As a material constituting the bag-like material, rubbers such as raw rubber and silicon rubber, and bags made of a thermoplastic resin such as polyethylene can be used. In the case of using the bag-like material under reduced pressure, such as a vacuum, a polymer material having a gas barrier performance of air in the range of 1 × 10 ⁻⁴ cc · cm / cm ² · S atmospheric pressure is preferable. It is because it will become difficult to maintain a pressure-reduced state, ie, to reduce the fluidity | liquidity of a heavy article, when lower than the said range.
[0024]
The base material (D) is a part or all of the reinforcing fiber of FRP, and is a mat, woven fabric, woven fabric, non-woven fabric, braided shape, three-dimensional woven fabric, knit shape, cotton shape, etc., and a mixture thereof. It can take various forms. As the fiber, continuous fiber, short fiber, and a mixture thereof can be applied.
[0025]
Since the base material (D) moves and deforms along the mold between the bag and the mold, it is preferable that the deformation resistance is small. Short fibers tend to have a smaller deformation resistance than long fibers, but the deformation resistance can be adjusted by deposits called binders, sealants and the like. That is, even in a base material in which reinforcing fibers are homogeneously distributed, the binder is locally dispersed and adhered, and the deformation resistance is locally increased or decreased to control the deformation direction of the base material in the preforming process. It is also possible to provide a portion that is completely fixed and does not deform.
[0026]
For base materials composed of long fibers, the deformation resistance may differ depending on the yarn density and the direction of arrangement, so the above binder may be used partially, short fibers may be added, and stitching (sewing processing) may be performed. The deformation resistance can be adjusted.
[0027]
When the base material is a woven fabric, the crossing point of the weaving yarn is the main location of deformation resistance, so use a woven fabric with a large number of crossing points to increase the deformation resistance, or vice versa. Thus, the deformation resistance can be reduced. The number of intersection points is the number of points where warp and weft yarns intersect each other within the unit area of the fabric, and the greater the number of intersection points, the more difficult the fabric is to deform, that is, the bag-like material follows the shape of the mold. It becomes difficult to move. Preferred fabric in the present invention, interlacing points are within the scope of 10,000 to 60,000 pieces / m ^2. More preferably, a woven fabric having a number of intersection points of 10,000 to 36000 / m ² described in JP-A-9-139325 is exemplified.
[0028]
Also, one of the other deformation resistances is a resistance force when pulling out the woven yarn (strand), which is called a yarn pulling force, and in a state where a woven base material having a size of 100 mm × 100 mm or more is placed on a plane, The maximum value F (gram) of the force (load) required to draw out the weaving yarn of length L (m) constituting the woven fabric in the longitudinal direction of the yarn is divided by L, and is expressed by F / L. The smaller weaving force of the weaving thread, the more it can follow the bag-like material and move to the required position for the required length, making it possible to manufacture preforms that are free of damage. . In the present invention, it is preferably 1 to 100 g / m or less. If it is below this range, the weaving yarn may fall off during handling of the fabric, and if it is above this range, the fabric may stretch at the corner portion or the like.
[0029]
Furthermore, in the case of a woven fabric, there is a possibility that the weaving yarn will be coarse and dense due to deformation, so that a woven fabric with few voids formed between the weaving yarns is preferable. Some of the gaps are represented by Cf in the cover factor, and as defined in Japanese Patent Laid-Open No. 7-118988, the area on the fabric is S1, and the area of the gap formed between the woven yarns in the area S1 Is defined by the following equation.
[0030]
Cover factor Cf = {(S1-S2) / S1} × 100
In the present invention, it is preferably 90% or more. If it is within this range, the preform will be free of woven threads even at the corners.
[0031]
The substrate is almost impossible or impossible to deform at the portion sandwiched between the bag and the mold, and the substrate in the portion where the heavy material in the bag has not yet flowed. While drawing all or part of it, deform it and follow the mold. The substrate may be singular or plural, and the singular may be shaped several times to form a plurality of preforms. In this case, precisely, the unshaped substrate is shaped between the bag and the already shaped substrate, but this does not depart from the concept of the present invention.
[0032]
After shaping, before removing the base material from the mold, fix it by spraying a fixing agent for fixing the shape to the base material, or by heating and melting part of the base material. There is no problem.
[0033]
Examples of the material of the substrate include inorganic fibers such as glass fibers and carbon fibers, and organic fibers such as Kevlar fibers and polyethylene fibers.
[0034]
The mold has the shape of the target preform, but has a material and a thickness that are not broken by the force acting when the heavy material flows along the mold. Specifically, it is a mold made of metal, FRP, graphite, wood or the like. Metals and graphite are characterized by being easy to heat and have a long service life. The FRP type is economical and can be manufactured in a short period of time.
[0035]
The surface of the mold is preferably smooth in order to suppress tearing or wrinkling when the substrate is deformed. Specifically, it is preferable that the surface smoothness is 0.5 mm or less. In addition, a lubricant or the like may be applied for the purpose of providing protrusions on the mold or improving fluidity for the purpose of locally stopping the movement of the substrate.
[0036]
The mold may be divided. It is also possible to intentionally divide the mold at a place where the shape of the mold is complicated and difficult for heavy objects to enter, and then move or vibrate several molds to form the desired shape after the heavy objects have flowed in. it can.
[0037]
Further, it is possible to adjust the shape by placing a small mold, which is referred to as a small size, on the mold.
[0038]
In addition, as shown in FIG. 5, an electromagnet 6, a permanent magnet, a mirror magnet, or the like can be arranged inside or partially in the mold, and a fluid such as metal can be attracted to the mold by a magnetic force. The electromagnet has a feature that the magnetic force can be easily released.
[0039]
Further, a temperature distribution can be given to the mold, and a part of the base material provided with the low melting point material can be melted. Of course, the mold or the substrate can be locally heated with light or hot air.
[0040]
In designing the mold, it is recommended to design in consideration of the preform manufacturing method, such as the shape of the corner portion. Determining the production method by integrating the bag-like material, heavy material, base material, mold, etc. is a shortcut for practically and efficiently implementing the present invention.
[0041]
Regarding the movement of the bag-like material, the shape and thickness of the bag-like material can be designed to control the flow direction and order of the heavy-weight material. However, on the outside of the bag-like material, for example, as shown in FIG. In addition, a spatula-shaped guide 5 may be provided, and the top of the bag-like object may be adjusted in the flow direction by this guide. The guide is not limited to a spatula or a plate, but may be a cylinder or a cylinder that can be divided in the axial direction and has a flared mechanism. The guide not only moves in one direction, but if shaping is not performed normally, it moves in the opposite direction to reshape, change the moving speed, or use it together with magnetic force adjustment etc. It is also possible to reshape.
[0042]
In addition, if a bag-like thing is a simple shape, it can be manufactured by blow molding or rotational molding. Also. It can also be produced by a dip method or a spray method. In order to make the thickness non-uniform with a complicated shape, a manufacturing method in which an elastomer is applied onto a mold for manufacturing a bag-like material by spraying or brushing and cured. It is also possible to manufacture by joining sheet-like elastomers. It is also possible to use different materials locally or use reinforcing materials such as polyethylene nets and meshes. By using the reinforcing material, the number of times the bag-like material can be used repeatedly and the durability can be improved. In addition, by adding a conductive substance such as metal or carbon to the material constituting the bag-like material, the bag-like material can be induction-heated. It can be used when forming.
[0043]
Further, it is preferable that the surface of the bag-like material is smooth so that the frictional resistance with the base material is not too large. In order to adjust the frictional force, it is possible to apply a low friction agent such as silicon powder.
[0044]
【Example】
The method for producing the preform of the present invention will be described with reference to examples.
Example 1
A bag-like product in which a 1 m square plastic bag (thickness 0.05 mm) was filled with sand (specific gravity 2.2, particle size 1 mm or less) was prepared.
[0045]
On the other hand, a short fiber glass mat (fiber diameter 13 μm, basis weight 300 g / m ² , thickness 0.6 mm) placed on an FRP mold having a hemispherical protrusion with a radius of 50 mm was prepared.
[0046]
The bag was started to contact from the top of the hemispherical protrusion of the mold, and the mat was deformed along the mold hemisphere while the bag was gradually lowered. After the bag-like material completely covered the hemispherical part, it was left as it was for 1 hour, and then the bag-like material was raised and the mat was removed from the mold. The mat was shaped into a hemisphere with a radius of 50 mm. Was a preformed preform.
(Example 2)
After spraying silicon diluted with a solvent on the surface of the FRP type in the shape of an elongated dome, the silicone is cured by applying pressure in an autoclave at 60 ° C. and 5 atm. The surface roughness is 2 microns, the left half is 1 mm, A bag-like product having a right half of 2 mm thickness and a length of 1 m was obtained. When a 10 mm × 60 mm strip tensile test piece was cut out from the silicon and subjected to a tensile test, the elongation was 400%.
[0047]
After setting this bag-shaped object in a dome-shaped female mold and filling the inside with hollow glass beads (specific gravity 2.5) having a particle size of 0.5 mm to 1 mm, a vacuum line hose is placed inside the bag-shaped object. The inside was connected to -760 mmHg. When the bag-like object was taken out from the female mold while maintaining this state, the bag-like object could be taken out without changing its shape and in the dome shape (length 1 m).
[0048]
On the other hand, on a metal mold (surface roughness 700 μm) having rectangular parallelepiped projections of 100 mm × 100 mm × 50 mm (height), carbon fiber strands (elastic modulus 235 GPa, elongation 2.1%, strength 50 GPa, number of single yarns 12,000) ) (The number of crossing points 15625, strand pull-out resistance 20 g / m, cover factor 97%) is placed, and the dome tip of the bag-like material is placed on the long side of the rectangular shape through the fabric at the center of the upper surface of the rectangular parallelepiped. The bag was pressed against the mold so that a portion with a thickness of 1 mm was present. Thereafter, air was introduced into the vacuum line, and the interior of the bag was reciprocated between −100 mmHg and −600 mmHg to gradually flow the glass particles. As for the bag-like material, the thickness of 1 mm first slid down as the lava flowed on the side of the rectangular parallelepiped, and gradually covered the entire surface of the rectangular parallelepiped. At this time, at the corner portion, the spatula was manually operated to prevent wrinkles from occurring on the fabric, and to guide the bag-like material into the corner portion. After the bag completely covers the mold, the inside of the bag is again set to -760 mmHg, the flow is stopped, and the mold is moved toward the upper side of the mold. I was able to.
[0049]
The base material was tightly deformed along the mold at the corner portion along the shape of the rectangular parallelepiped.
[0050]
Furthermore, after applying an epoxy adhesive to the base material and then removing it from the mold, a preform having a rectangular parallelepiped shape was obtained.
(Example 3)
In Example 2, the heavy object was a steel bearing having a particle diameter of 1 mm (specific gravity 7.9), and the electromagnet was embedded in the mold at the location corresponding to the corner of the rectangular parallelepiped, in exactly the same manner as in Example 2, The carbon fiber fabric was shaped and preformed into a rectangular shape. As a result, it was confirmed that at the corner portion, the frequency of manipulating the spatula was smaller than that in Example 2 due to the action of magnetic force, and it was possible to form the shape more easily.
Example 4
Using a bag-like material filled with the same fluid as in Example 2, a polyethylene film having a thickness of 30 μm was placed on a metal mold having a convex curved surface with a curvature of 300 mm, and a carbon fiber fabric was formed thereon. A prepreg (woven fabric is coconut weave, fiber basis weight 200 g / m ² , fiber content 47%) is further provided with a 30 μm-thick polyethylene film. Pressed on the film. The pressing started from the top of the convex surface.
[0051]
The prepreg and the polyethylene film were fitted into a convex shape, and a convex preform having a curvature of 300 mm was obtained which was sandwiched with the polyethylene film. Because this preform is sandwiched with polyethylene film, it is less likely to be polluted by the environment such as adhesion of dust, and even if it is held by hand, the resin does not adhere to the hand like a normal prepreg, handling characteristics Was very good.
[0052]
【The invention's effect】
According to the present invention, it is possible to manufacture a preform having a complicated shape more easily and stably than in the prior art, thereby contributing to high production efficiency of FRP molding. In addition, the shaping process can be simplified and automated, contributing to the development of the FRP industry.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a method for producing an FRP molding substrate according to the present invention.
FIG. 2 is a schematic diagram showing the next stage of FIG. 1;
FIG. 3 is a schematic diagram showing the next stage of FIG. 2;
FIG. 4 is a schematic diagram showing a further next stage of FIG. 3;
FIG. 5 is a schematic view showing another example of the method for producing an FRP molding substrate according to the present invention.
[Explanation of symbols]
1: Heavy load (A)
2: Bag (B)
3: Mold (C)
4: Substrate (D)
5: Guide 6: Magnet

Claims (8)

A bag (B) containing a granular material having a specific gravity of 2.2 to 7.9 and containing fluidity (A), and a mold (C) having a desired shaping shape (C) ), And (A) flows inside (B), (B) spreads along (D), and (D) becomes the shape of (C). A method for producing a substrate for FRP molding, characterized by shaping. The fluidity of (A) is controlled by the pressure inside (B), The manufacturing method of the base material for FRP shaping | molding of Claim 1 characterized by the above-mentioned. Method for producing a bag-like material (B) is claim 1 or 2 FRP molding base material according to, comprising the stretchable material. The said base material (D) consists of a textile fabric, and the extraction resistance of the strand which comprises a base material (D) exists in the range of 1-100 g / m, The Claim 1 characterized by the above-mentioned. A method for producing a substrate for FRP molding. The method for producing a substrate for FRP molding according to any one of claims 1 to 4 , wherein a particle size of the heavy article (A) is 5 mm or less. Direction or spread of bag-like objects, heavy moving direction of the bag-like objects FRP molding substrate according to any one of claims 1 to 5, characterized in that controlled by the obstacle provided around the the Production method. For FRP molding in which (B) spreads along the base material (D) and (D) is shaped into the shape of the mold (C) as the heavy material (A) flows inside the bag-like material (B) A bag-like product comprising a granular material having a specific gravity of 2.2 to 7.9 and having fluidity for producing a base material and having fluidity therein (A). 8. The bag-like product according to claim 7, wherein the thickness is non-uniform.

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