JP2000202614A - Preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothen the flow of molten metal, to reduce the portion faced to the flow vertically crossing to the molten metal flow, and to thereby prevent the breakage and form a sound fiber reinforcing composite material by chamfering the outer peripheral surface of a cylindrical end surface at flow-in side matrix metal in the casting time. SOLUTION: The angle of chamfer on a preform in formed as >=45 deg. to the cylindrical end surface, and it is desirable to arrange the roundness between the chamfer and the end surface. The preform 2 is formed as a hollow cylindrical shape having the hollow part 2h by combining and fixing the reinforcing fiber with binder by using a slurry method, etc. The outer peripheral surface 2e and the inner peripheral surface 2i are formed between the end surface 2f at the flow-in side of the molten metal and the end part 2g at the lower side. Further, the outer peripheral 2s side of the cylindrical end part 2f in the preform 2 is chamfered and formed to the tapered shape having the tapered surface 2t. The roundness is formed at the portion of the tapered surface 2t in contact with the outer peripheral surface 2s to smoothen the flow-in of the molten metal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preform (fiber-reinforced preform) of a metal-based composite material which is frequently used for automobile parts such as engine blocks.

[0002]

2. Description of the Related Art In the field of materials such as automobile manufacturing, there is a metal matrix composite material (MMC: Metal Matrix Composite) in which different materials are combined to have desired characteristics. Fiber reinforced metal matrix composite material (FRM: FIBER REINFORCED) using ceramic fibers such as silicon carbide whisker fibers as reinforcing fibers and a light metal such as aluminum, titanium, magnesium, etc. as matrix metal.
METAL).

[0003] This fiber-reinforced metal matrix composite material has been developed as a structural material with the aim of producing a light and durable material, and since it can have a complicated function which cannot be expected with a single material, It has also been used extensively in the field of automobiles, where weight reduction has progressed significantly.

Such a fiber-reinforced metal matrix composite material typified by alumina fiber and aluminum alloy is, for example, as shown in FIG. 6, bolted portions (boss portions) 45, 46 of a casting part such as a cylinder block 50. , 47 and the crank journal thrust section 48 are used to increase the structural strength.

[0005] In the case of manufacturing this fiber-reinforced metal matrix composite member, reinforcing fibers are fixed in advance to a part of a product mold such as a cylinder block to be reinforced by a binder.
A preform (fiber-reinforced preform) formed into a predetermined shape such as a cylindrical shape is preheated between 300 ° C. and 800 ° C., then assembled, and a molten metal in which a matrix metal is melted is poured into the preform. 4904kPa (500kgf / c
m ² ) to 9807 kPa (1000 kgf / cm ² ) to infiltrate the molten metal into this preform, die casting or melt forging (squeeze casting)
And the like.

In the prior art, this fiber reinforced metal matrix composite member is formed by casting a cylindrical preform 20 using a cylindrical preform 20 having a hollow portion 20h as shown in FIGS. It is sometimes manufactured by pressure casting while being arranged in the passage of the molten metal.

[0007]

However, in the space between the preform 20 and the mold 3, the gap C serving as the passage 80 for the molten metal is narrowed in order to minimize the portion where the reinforcement of the product is weak. When the molten metal passes through the preform 20, a large force is applied to the inflow-side end 20f, and a part of the end 20s is broken and chipped.

If the gap C is small, the air or gas is accumulated and it is difficult for the molten metal to pass through, and the molten metal does not sufficiently reach the outer peripheral surface 20s of the preform 20, so that the preform 20 is evenly distributed from the surroundings when the molten metal is pressurized. The preform 20 is not pressurized, and receives an uneven pressure.

Furthermore, the set preform 20 may be deformed and broken, a cavity may be formed in the matrix metal portion, or a complex defective portion where the impregnation of the reinforcing fiber is insufficient may occur. As a result, the quality of the fiber-reinforced composite member deteriorates.

In particular, when the portion to be strengthened is long and the preform 20 has a long cylindrical shape, the preform 20
This is especially important for the surrounding area.
In order for the molten metal of the matrix metal to penetrate between the reinforcing fibers, it is necessary that the molten metal is sufficiently circulated around the preform 20 so that uniform pressurization can be performed.

In order to prevent the occurrence of such defects, the peripheral wall of the preform 20 or the gap C for the passage is provided relatively large so that the molten metal is supplied to the periphery of the preform 20 and the pressure at the time of pressurization is equalized. It has been found that it is effective to propagate to

However, if the clearance C for the passage 80 is to be increased to a certain extent, the outer diameter D of the preform 20 becomes smaller by that amount, and the portion where the reinforcing fibers are distributed becomes smaller. And the reinforcement becomes insufficient. Further, since the surface area of the fiber portion is also reduced, there is a problem that the area of the interface between the fiber of the preform and the matrix metal is reduced, and the strength of the entire interface is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to form a tapered shape by chamfering the tip side of a cylindrical preform so that the flow of molten metal during casting can be improved. Preform that can prevent damage to the preform and form a sound fiber-reinforced composite member by reducing the portion of the melt that faces perpendicularly to the flow of the molten metal. Is to provide.

[0014]

A preform (fiber-reinforced preform) for achieving the above object is used for a fiber-reinforced metal matrix composite member formed of a reinforcing fiber and a matrix metal. The cylindrical preform is formed by chamfering the outer peripheral side of the cylindrical end face on the side into which the molten metal of the matrix metal at the time of casting flows.

That is, the end of the preform is formed in a tapered shape with respect to the inflow direction of the molten metal during casting.
By reducing the portion of the surface perpendicular to the inflow direction, the flow of the molten metal at the time of inflow of the molten metal is prevented and the end of the preform is prevented from being damaged.

According to the above construction, since the outer peripheral side of the end of the cylinder of the preform is formed in a tapered shape, the flow of the molten metal can be made smooth and the flow of the molten metal during casting can be improved. Pressing on the preform becomes more uniform and isobaric. In addition, a taper surface that is oblique to the inflow direction of the molten metal is provided, minimizing the area perpendicular to the flow of the molten metal, and deflecting the flow hitting the preform by skewing it, preventing damage to the preform Is done.

Preferably, the chamfer angle of the chamfer is set to 45 degrees or more with respect to the end surface of the cylindrical shape. Can be cast at the filling rate of the molten metal at the time of die casting. This numerical value of 45 degrees is a value obtained experimentally.

Even when the chamfer angle is 45 degrees or less, it is possible to prevent breakage of the preform by casting the molten metal at a lower filling speed than the current filling speed. The slow speed will reduce the efficiency of the casting operation. Furthermore, when a roundness is provided between the chamfer and the end face, the flow of the molten metal becomes smooth,
Since the easily breakable corners are eliminated, breakage of the preform can be further avoided.

Although the reinforcing portion of the preform according to the present invention is described here as a bolt boss of a cylinder head or a cylinder body of an engine, the bolt boss is basically described. The present invention can be applied to any part as long as the part is reinforced with a preform into a cylindrical shape.

The method of manufacturing a fiber-reinforced metal matrix composite member using the preform is directed to a casting method in which the reinforcing fibers of the preform can be impregnated with a molten metal to form a composite. It can be applied to methods such as casting and squeeze casting.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. With respect to the preform (fiber-reinforced preform) according to the present invention, bolt fastening portions (boss portions) 45, 4 of a cylinder block 50 of an engine as shown in FIG.
The preforms 25, 26, and 27 used for strengthening 6, 47, the crank journal thrust portion 48, and the like will be described as examples.

These preforms 25, 26, and 27 are also called reinforcing fiber aggregates. Prior to casting, reinforcing fibers are bonded and fixed in advance with a binder to form a hollow fiber as shown in FIGS. The fiber-reinforced metal composite member is formed in a cylindrical shape such as a cylindrical shape, arranged at a portion to be reinforced in a mold before casting, and pressure-cast with a matrix metal.

The reinforcing fibers of the preforms 25, 26, and 27 include alumina fibers, alumina-silica fibers, carbon fibers, silicon carbide fibers, boron fibers, and combinations thereof. There are synthetic resin binders such as furan resin, acrylic resin and epoxy resin, and ceramic binders of inorganic substances such as alumina and silica, and these can be used in combination.

Then, this preform is formed by binding reinforcing fibers with a binder by a slurry method or the like to be described later and forming a hollow cylindrical shape having a hollow portion 2h at the center as shown in FIGS. An outer peripheral surface 2s is provided between the end 2f on the side (upper side in the figure) into which the molten metal flows and the lower end 2g.
And an inner peripheral surface 2i are formed. Further, as shown in FIG.
The outer peripheral 2s side of the cylindrical end 2f of the hollow cylindrical preform 2 is chamfered to form a tapered shape having a tapered surface 2t.

The portion of the tapered surface 2t which is in contact with the end surface 2f of the cylinder is formed flat as shown in FIGS. 1, 2 and 4, leaving the corners K1 and K3, leaving the molds of the preforms 2 and 2B. Although the setting at the time of assembling can be facilitated, as shown in FIG. 3 and FIG. 5, the roundness 2r having the radius R1 is provided to form the rounded regions B2 and B4, so that the inflow of the molten metal can be more smoothly performed. .

The portions where the tapered surface 2t contacts the outer peripheral surface 2s of the cylinder 2 can also be crossed as shown in FIGS. 1, 2 and 3 to form the corners L1 and L2. As shown in FIG. 4 and FIG. 5, the rounded areas C3 and C4 are formed with the roundness 2p having the radius R2, so that the flow of the molten metal can be further smoothed.

That is, in FIGS. 1 and 2, the tapered surface 2t
Only a flat tapered (inclined) region A1 is formed. In FIG. 3, in addition to the flat tapered region A2, a rounded region B2 is formed on the end side to form a tapered surface 2a.
In FIG. 4, the flat tapered region A3 and the outer peripheral surface 2s
5, a flat inclined area A3, a rounded area B4 on the end face 2f side, and a rounded area C4 on the outer peripheral face 2s are formed in FIG.

In short, the tapered shape with respect to the end 2f on the inflow side of the molten metal reduces the area of the surface 2f perpendicular to the inflow direction of the molten metal, which obstructs the flow of the molten metal, so that the preforms 2, 2A, 2 2B, 2C (hereinafter represented by 2)
Any shape may be used as long as it can fill the periphery of the melt. For the sake of strength distribution and manufacturing convenience, a shape that does not hinder the flow of the molten metal even if a taper portion shape different from the shape shown in FIGS. I just need.

These preforms 2 can be manufactured by a slurry method, an embossing method, or a papermaking method for short fibers. However, forming the tapered surface 2t on these preforms 2 is a problem in some preform manufacturing. It can be performed in a process. That is, the chamfered shape may be provided on the guide of the end face portion 2f in the suction adhesion step in the method of using the liquid tank of the slurry method, or the chamfered shape may be provided on the pressing roller when squeezing out moisture. Further, chamfering may be performed by machining after drying or firing. In the mold forming method of the slurry method, the taper surface 2t of the preform 2 can be formed using a mold having a taper surface. Next, a method of manufacturing the fiber reinforced cylinder block 50 using the preform 2 will be described.

During the assembly of the cylinder block 50 mold,
Preforms 25, 26, 27, and 28 (hereinafter, represented by 2) prepared in advance corresponding to the reinforced portions 45, 46, 47, and 48 are arranged, and the mold assembly is completed. At this time, if necessary, the preform 2 is arranged using a shape maintaining body (not shown), a positioning assisting member 55, or the like. Degree to 8
Preheat to 00 degrees.

After the casting of the mold, a molten metal of the aluminum alloy is poured from a pouring port and pressurized. At the time of this pouring, the molten metal circulates in the circumferential direction of each preform 2 as a part of the path of the matrix metal that has melted the tapered surface portion 2t of each preform 2 and is about 4904 kPa (500 k
gf / cm ² ) to 9807 kPa (1000 kgf / c)
When the pressure is applied at m ² ), the pressure is transmitted through this passage, so that the reinforcing fibers of each preform 2 are impregnated with the matrix metal, which is a molten metal, to form intermetallic compounds and bond.

After cooling, the mold is separated, the product is taken out, and if necessary, the shape maintaining body (not shown), the positioning auxiliary member 55, etc. are removed, and the shape is adjusted by machining to obtain the fiber. A fiber-reinforced cylinder block 50 that is a reinforced metal matrix composite member can be obtained.

According to the preform (reinforced fiber preform) 2 having the above structure, the molten metal can be circulated through the tapered surface 2t provided on the outer periphery of the preform 2 at the time of casting. Can be pressurized from the entire circumference, so that pressurization can be performed more evenly.

Further, since the area of the end face 2f orthogonal to the flow of the molten metal is reduced when the molten metal flows into the molten metal, damage such as internal cracking or chipping of the end face 2f can be prevented. Can evenly pressurize from
The deformation and breakage of the preform 2 can be prevented. Therefore, since the molten metal can be efficiently permeated, the impregnation of the matrix metal into the reinforcing fibers can be made sufficient, and a high-quality fiber-reinforced composite member 50 can be obtained.

[0035]

As described above, according to the preform (reinforced fiber preform) of the present invention, the outer peripheral side of the end of the cylinder of the preform is formed in a tapered shape.
Since the flow of the molten metal can be smoothed and the flow of the molten metal during casting is improved, the pressure on the preform can be made more uniform and uniform.

In addition, a tapered surface that is inclined with respect to the inflow direction of the molten metal is provided to reduce the area of the end surface perpendicular to the flow of the molten metal, so that the force due to the inflow pressure applied to this end portion is reduced. This can prevent the end from being damaged. Therefore, the molten metal can be efficiently penetrated, so that the matrix metal can be sufficiently impregnated into the reinforcing fibers, and a high-quality fiber-reinforced composite member can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a preform according to a first embodiment of the present invention.

FIG. 2 is a side view of the preform of FIG.

FIG. 3 is a side view of a preform according to another embodiment of the present invention.

FIG. 4 is a side view of a preform according to another embodiment of the present invention.

FIG. 5 is a side view of a preform according to another embodiment of the present invention.

FIGS. 6A and 6B are diagrams of an engine cylinder block showing a reinforced portion using a preform, FIG. 6A is a schematic perspective view, FIG. 6B is a partial cross-sectional view showing a reinforced portion K, and FIG.
Is a partial cross-sectional view seen from the arrow X direction.

FIG. 7 is a perspective view showing a setting state of a preform of the related art.

FIG. 8 is a perspective view showing a conventional preform.

[Explanation of symbols]

 2, 2A, 2B, 2C Preform 2f end (inflow side of molten metal) 2g end 2h, 20h hollow 2i inner peripheral surface 2s outer peripheral surface 2t taper surface

Continuing from the front page (72) Inventor Munehiko Hasegawa 8 Dosa, Fujisawa-shi, Kanagawa Prefecture, Isuzu Central Research Institute Co., Ltd. (72) Inventor Eiji 8 Shiya, Fujisawa-shi, Kanagawa Prefecture, Isuzu Central Research Institute Co., Ltd. (72) Inventor Yuichiro Hara 8 Dosa, Fujisawa-shi, Kanagawa Prefecture, in Isuzu Central Research Institute Co., Ltd.

Claims (3)

[Claims] 1. A cylindrical preform used for a fiber-reinforced metal matrix composite member formed of a reinforcing fiber and a matrix metal, wherein an end surface of the cylindrical shape on a side into which a molten metal of a matrix metal at the time of casting flows. A preform formed by chamfering the outer peripheral side. 2. The preform according to claim 1, wherein the chamfered angle of the chamfer is set to 45 degrees or more with respect to the end face of the cylindrical shape. 3. The preform according to claim 1, wherein a roundness is provided between the chamfer and the end face.