JPH05125467A - Production of fiber-reinforced composite member - Google Patents

Abstract

PURPOSE:To decrease the pressing force when molten metal is filled in a fiber formed body and to improve the quality of a piston for the internal combustion engine at the time of producing the piston with the whole reinforced with the fiber. CONSTITUTION:A heat insulating region B is provided around a piston casting region A in the cavity C of a lower die 5. A fiber formed body 13 is set in the region A, molten metal is then filled under pressure in the cavity C, and the molten metal is infiltrated into the body 13 from its outer surface. In this case, since the body 13 and the molten metal infiltrated into the body are thermally insulated by the molten metal in the region B, the viscosity of the molten metal is kept low in the body 13 even under low pressure, hence the molten metal flows sufficiently, the body 13 is filled with the molten metal, and further the shape of the body 13 is maintained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a fiber-reinforced composite member.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing this kind of member,
A fiber molded body made of reinforcing fibers is placed in the cavity of the mold, and then the molten metal is injected into the cavity and the molten metal is pressurized, so that the fiber molded body is filled with the molten metal to cast a fiber-reinforced composite member, Such methods are known.

[0003]

However, according to the above-mentioned conventional method, since a high pressurizing force is required when the molten metal is filled in the fiber molded body, the casting apparatus becomes large in size and the apparatus cost increases. It is difficult to stably mass-produce high-quality members because the fiber molded body may be damaged due to heat generation. Many machines are used because the molten metal is cooled by the mold and the molten metal unfilled portion easily occurs on the surface layer of the member. There are problems such as having to take a finishing machining allowance.

In view of the above, the present invention is capable of stably mass-producing high-quality fiber-reinforced composite members which can reduce the pressure applied when filling molten metal into a fiber molding and have a small machining finishing cost. It is an object of the present invention to provide the above-mentioned manufacturing method capable of achieving the above.

[0005]

In the method for producing a fiber-reinforced composite member according to the present invention, the cavity has a member casting region and a molten metal heat retaining region which is continuous with the member casting region and surrounds the region. In the region, a mold provided with a plurality of ridges extending from the outer peripheral edge of the region to the boundary of the member casting region is used, and a fiber molded body made of reinforcing fibers is installed in the member casting region, and then the cavity By injecting molten metal into the molten metal and pressurizing the molten metal, the molten metal is filled and composited in the fiber molded body in the member casting region to cast a fiber reinforced composite member and the fiber reinforced composite member in the molten metal heat retaining region. And casting a scrap portion having a plurality of slits formed by the ridge, and then removing the scrap portion from the fiber-reinforced composite member. And butterflies.

[0006]

1 to 6 show a first embodiment for manufacturing a piston for an internal combustion engine as a fiber reinforced composite member.

In FIG. 1, a piston 1 is fiber-reinforced as a whole, and comprises a cup-shaped fiber molded body having the same shape and substantially the same size as the piston 1, and a matrix material filled and compounded in the fiber molded body. Composed. The fiber molded body is composed of 50% by volume of silicon carbide short fibers and 50% by volume of alumina short fibers. The volume fraction Vf of the fiber molded body in the piston 1 is 14%. The matrix material is made of magnesium alloy (ZC63 material).

2 and 3 show a casting apparatus for producing a piston 1, which is a mold 2 as a mold.
And a plunger 3 slidably fitted in the mold 2. The mold 2 is composed of an upper mold 4 and a lower mold 5. The upper mold 4 has a cylinder hole 6 into which the plunger 3 is fitted, and a frustoconical basin 7 which is continuous with the cylinder hole 6 and opens toward the lower mold 5. Further, the lower die 5 has an inverted frustoconical recess 8 opening toward the basin 7, and the opening area of the recess 8 is larger than the opening area of the basin 7.

A core 11 for molding the pin boss 9 and the cavity 10 of the piston 1 is provided at the center of the bottom surface of the recess 8. Therefore, the central region of the piston shape including the core 11 in the chain line in FIG. 3 is the piston casting region A as the member casting region, while the peripheral region between the piston casting region A and the inner peripheral surface of the recess 8 is , A molten metal heat retaining region B which is continuous with the piston casting region A and surrounds the region A, and both regions A and B form a cavity C ₁ .

In the molten metal heat retaining region B, three ridges 12 are provided in parallel with each other in each half of the molten metal heat retaining region B. Each ridge 12 extends from the outer peripheral edge of the molten metal heat retaining region B, and hence from the inner peripheral surface of the cavity C ₁ . It extends to the boundary c of the piston casting area A.
In each half, the two ridges 12 on both sides extend in the tangential direction of the piston casting area A, and the remaining one ridge 12 on both sides.
There are two halves in between. Each ridge 12 is a cavity C
It has the same height as the depth of ₁ .

Next, the manufacture of the piston 1 will be described.

First, the fiber molded body 13 is manufactured through the following steps. (A) A sand core molding die is filled with coated sand, and the coated sand is heated to 300 ° C. to bond them to each other, whereby a sand having a hollow structure having an outer shape corresponding to the core 11 is formed. Mold the core. (B) 58.3 g of alumina short fibers having a diameter of 3 μm and 56.0 g of silicon carbide short fibers having a diameter of 0.5 μm were put in an aqueous solution having a water-soluble binder concentration of 8% and mixed for 10 minutes, and then ultrasonic waves for 5 minutes. Disintegration treatment is performed to prepare a slurry-like molding material. (C) A sand core is installed in the cylindrical portion of the vacuum suction molding device, and then a molding material is injected into the cylindrical portion, and at the same time, dehydration treatment is performed from the bottom surface side of the cylindrical portion under the condition of a vacuum degree of -65 cmHg to form a fiber molding Mold 13. The fiber molded body 13 has the same shape and substantially the same size as the piston 1. (D) The fiber molded body 13 is taken out from the vacuum suction device together with the sand core, the fiber molded body 13 is then dried, and then the sand core is disintegrated at a heating temperature of 450 ° C.
The binder is burned off at 0 ° C. The volume fraction Vf of the cup-shaped fiber molded body 13 thus obtained is 14%.

In casting the piston 1, first, the fiber molding 13 is heated at 700 ° C. for 15 minutes or more, and the die 2 is preheated to 300 ° C. Next, as shown in FIG. 4, the fiber molded body 13 is fitted into the core 11 and installed in the piston casting region A, and then the upper and lower molds 4 and 5 are closed to form the cavity C ₁ , the basin 7 and the cylinder. 760 ± 2 ℃ in hole 6
About 1.6 kg of molten magnesium alloy is injected, and the plunger 3 is lowered to bring about 91.1 molten metal.
Pressure is applied under the condition of MPa to fill the cavity C _{1 and the} like.

With this pressurization, the molten metal permeates from the outer surface of the fiber molded body 13 into the inside thereof, and at this time, the fiber molded body 13 and the molten metal that has penetrated into the molten metal heat retaining region B and the pool 7
Since the temperature is maintained by the molten metal, the molten metal is kept at a low viscosity and sufficiently flows in the fiber molded body 13, whereby the fiber molded body 13 is filled with the molten metal. In this case, the time from pouring to filling the fiber molded body 13 with the molten metal is about 20 seconds.

Since the liquid phase flow of the molten metal is used as described above, the molten metal can be filled in the fiber molding 13 even if the pressure applied to the molten metal is as low as about 91.1 MPa. Of about 150 MPa.

Further, by adopting this low applied pressure, it is possible to prevent damage to the fiber molded body 13. This is because when the entire member such as the piston 1 is fiber reinforced, the fiber molded body has a complicated shape. It is particularly effective when it has a thin portion and has a thin portion, and moreover enables stable mass production of the member.

By the casting operation, the casting 14 shown in FIGS. 5 and 6 is obtained. The casting 14 includes the piston 1 cast in the piston casting region A and the molten metal heat retaining region B.
1st scrap part 1 that is cast inside and continues to piston 1
5 ₁ and a convex second scrap portion 15 ₂ which is cast in the pool 7 and the cylinder hole 6 and is continuous with the piston 1 and the first scrap portion 15 ₁ . Further, the first scrap portion 15 ₁ has a plurality of slits 16 formed by each ridge 12.

From the casting 14 to the first and second scrap parts 1
By removing 5 ₁ and 15 ₂ , the piston 1 shown in FIG. 1 is obtained.

In this scrap portion removing operation, first, the first scrap portion 15 ₁ to the second scrap portion 15
₂ was cut, and then the second scrap portion 15 ₂ was cut into the cast product 14 and heated at 430 ° C. for 6 hours and at 80 ° C.
Apply thermal shock, including cooling with warm water at ° C. There is a large thermal expansion difference between the fiber-reinforced piston 1 and the first scrap portion 15 ₁ made of only the matrix material, and the first scrap portion 15 ₁ has a plurality of slits 16
Because of the thermal shock, a crack is generated at the end of the first scrap portion 15 _{1 on} the piston 1 side due to the thermal shock. After that, when a wedge is driven into each slit 16, the first scrap portion 15 ₁ is easily separated from the piston 1 with the outer surface of the piston 1 as a boundary.

In the piston 1, the fiber molded body 13 maintains a normal shape, and the inside thereof is filled with the matrix material obtained from the molten metal, so that the quality is high. Since the dimension of is substantially the same as the dimension of the fiber molded body 13, the machining allowance is small.

The first and second scrap parts 15 ₁ and 1
Since 5 ₂ can be reused as a casting material, the economical loss due to the provision of the molten metal heat-retaining region B, the pool 7 and the like hardly occurs.

7 to 12 show a second embodiment for producing a connecting rod for an internal combustion engine as a fiber reinforced composite member.

In FIG. 7, the connecting rod 17 is entirely reinforced with fibers, and is composed of a plate-shaped fiber molded body having the same shape and substantially the same size as the connecting rod 17, and a matrix material filled and compounded in the fiber molded body. To be done. The fiber molded body is molded under the application of the vacuum suction molding method in the same manner as described above, is composed of silicon carbide short fibers having a diameter of 0.5 μm, and has a volume fraction V of the fiber molded body in the connecting rod 17.
f is 20%. The matrix material is made of aluminum alloy and its composition is 0.5 wt% Si, 3 wt% C
u, 0.5 wt% Mg and the balance Al.

8 and 9 show a casting device for producing the connecting rod 17, which comprises a mold 18 as a mold and a plunger 19 slidably fitted in the mold 18. Is equipped with. The mold 18 is an upper mold 20 and a lower mold 21.
And consists of. The upper mold 20 has a cylinder hole 22 into which the plunger 19 is fitted, and a hot water pool 23 which is continuous with the cylinder hole 22 and opens toward the lower mold 21, and the open shape of the hot water pool 23 is the connecting rod 17. It is close.
Further, the lower mold 21 has a recess 24 that opens toward the pool 23.
The opening area of the recess 24 is equal to the opening area of the basin 23.

At both ends in the longitudinal direction of the bottom surface of the recess 24,
Positioning pins 27 and 28 for the fiber molded body are provided at positions corresponding to the large end portion 25 and the small end portion 26 of the connecting rod 17. Therefore, the central region of the connecting rod shape including both positioning pins 27 and 28 in the chain line in FIG. 9 is the connecting rod casting region D as the member casting region, while the connecting rod casting region D and the inner peripheral surface of the recess 24 are located between the connecting rod casting region D and the recess 24. The peripheral region is a molten metal heat retaining region E which is continuous with the connecting rod casting region D and surrounds the region D, and both regions D, E form a cavity C ₂ .

In the molten metal heat-retaining area E, three projections 29 surround the casting areas d ₁ and d ₂ on the large-end casting area d ₁ and the small-end casting area d ₂ sides of the connecting rod casting area D. The protrusions 29 extend from the outer peripheral edge of the molten metal heat-retaining region E, that is, the inner peripheral surface of the cavity C ₂ to the boundary f of the connecting rod casting region D. In addition, each positioning pin 27, 28
And each ridge 29 has the same height as the depth of the cavity C ₂ .

In casting the connecting rod 17, first,
A plate-shaped fiber having the same shape and substantially the same size as the connecting rod 17.
Heat the molded body 30 at 700 ° C for 15 minutes or longer, and
Preheat mold 18 to 300 ° C. Then, as shown in FIG.
The fiber molding 30 is provided with the positioning holes 3 on the large and small end sides.
Insert both positioning pins 27 and 28 into
It is installed in the rod casting area D, and then the upper and lower molds 20, 21
Close cavity C ₂, Pool 23 and cylinder hole
The molten aluminum alloy of about 760 ℃ is poured into No. 22,
Then, the plunger 19 is lowered to add the molten metal.
Press cavity C₂Etc.

Along with this pressurization, the molten metal permeates from the outer surface of the fiber molded body 30 into the inside thereof, and at that time, the fiber molded body 30 and the molten metal that has penetrated into the molten metal heat retaining area E and the pool 2
Since it is kept warm by the molten metal of No. 3, the fiber molded body 30
Inside, the molten metal is kept at a low viscosity and flows sufficiently, whereby the fiber molding 30 is filled with the molten metal. In this case, the pressure applied to the molten metal is set to about 10 MPa.

By the above casting operation, a casting 33 shown in FIGS. 11 and 12 is obtained. The casting 33 is formed by connecting the connecting rod 17 cast in the connecting rod casting region D and the connecting rod 17 that is cast in the molten metal heat retaining region E and is continuous with the connecting rod 17.
Scrap part 34 ₁ , pool 23 and cylinder hole 2
And a hook-shaped second scrap portion 34 ₂ continuous with the connecting rod 17 and the first scrap portion 34 ₁ . The first scrap portion 34 ₁ has a plurality of slits 35 formed by the protrusions 29.

From the casting 33 to the first and second scrap parts 3
By removing 4 ₁ and 34 ₂ , the connecting rod 17 shown in FIG. 7 is obtained. This scrap part removal work is
The same method as described above is used.

In the connecting rod 17, the fiber molded body 30
Maintains a normal shape, and the inside thereof is filled with a matrix material obtained from the molten metal, so that the quality is high, and the dimension of the connecting rod 17 is substantially the same as the dimension of the fiber molded body 30. Since they are the same, the machining finishing allowance is very small.

According to the present invention, the molten metal can be filled into the fiber molding even if the pressure applied to the molten metal is as low as 0.5 MPa.

[0033]

EFFECTS OF THE INVENTION According to the present invention, the pressing force at the time of filling molten metal into a fiber molding can be significantly reduced as compared with the conventional method, and the fiber reinforced composite member is of high quality and has a small machining finishing cost. Can be mass-produced stably.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a piston.

FIG. 2 is a vertical sectional view showing a first example of a casting apparatus.

FIG. 3 is a view on arrow 3-3 in FIG.

FIG. 4 is a vertical cross-sectional view showing a state where a fiber molded body is installed in a lower mold.

FIG. 5 is a vertical sectional view showing a first example of a cast product.

6 is a view taken in the direction of arrow 6-6 of FIG.

FIG. 7 is a plan view of a connecting rod.

FIG. 8 is a vertical sectional view showing a second example of the casting apparatus.

9 is a view taken along the arrow 9-9 of FIG.

FIG. 10 is a plan view showing a state where the fiber molded body is installed in the lower mold.

FIG. 11 is a vertical cross-sectional view showing a second example of the cast product.

12 is a view on arrow 12-12 of FIG.

[Explanation of symbols]

1,17 Pistons, connecting rods (fiber reinforced composite members) 2,18 Molds (molds) 12,29 Projected ridges 13,30 Fiber compacts 15 ₁ , 34 ₁ 1st scrap part 16,35 Slits A, D Piston casting area , Connecting rod casting area (member casting area) B, E molten metal heat retaining area C ₁ , C ₂ cavity c, f boundary

Claims (1)

[Claims] 1. A cavity (C₁, C₂) Is a component casting
Connect to the area (A, D) and its member casting area (A, D).
And a molten metal heat insulation area surrounding the area (A, D)
(B, E), and the molten metal heat retention area (B, E) has
The member casting region from the outer peripheral edge of the region (B, E)
A plurality of ridges (1 extending to the boundary (c, f) of (A, D)
Using a mold (2, 18) provided with
Fiber molding made of reinforcing fibers in the member casting area (A, D)
Place the body (13, 30), then the cavity (C
₁, C₂) To inject the molten metal into and pressurize the molten metal.
The fiber molded body in the member casting region (A, D)
(13, 30) filled with molten metal and compounded to form fiber-reinforced composite part
Casting the material (1, 17) and holding the molten metal
Connect to the fiber-reinforced composite member (1, 17) in (B, E).
And formed by the ridges (12, 29)
Scrap part (15) with a number of slits (16, 35)
₁, 34₁) And then the fiber reinforced composite member
From (1,17), the scrap part (15₁, 34₁)
For manufacturing fiber-reinforced composite members characterized by removing
Law.