JPH0755367B2 - Casting method for fiber reinforced cylinder block material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to a method for casting a fiber-reinforced cylinder block material used in an engine, particularly a cylinder-bore structure composed of a tubular fiber-reinforced composite material. Regarding

(2) Conventional technology In the past, when casting this type of material, the preheating temperature of the fiber molded body was set to be higher than the heating temperature of the cylinder bore molding core in the mold in order to improve the filling property of the molten metal into the fiber molded body. It is set to be high.

(3) Problems to be Solved by the Invention However, when the temperature setting as described above is performed between the fiber molding and the core, the temperature gradient generated in the fiber molding when the molten metal is injected into the mold There is a problem that a part that gently descends is formed on the outer peripheral surface in contact with the molten metal and the vicinity thereof, and casting defects such as microporosity and partial damage of the fiber molded body occur in the part.

It is an object of the present invention to provide the casting method that can solve the above problems.

B. Structure of the Invention (1) Means for Solving Problems The present invention is to mold a cylinder bore forming core of a mold for casting a fiber reinforced cylinder block material composed of a tubular fiber reinforced composite around the cylinder bore. When a molten metal is poured into the mold by fitting a tubular fiber molded body into the mold, the fiber molded body is rapidly abutted from the outer peripheral surface side in contact with the molten metal to the inner peripheral surface side in contact with the core. And, in order to generate a temperature gradient that drops substantially linearly, the heating temperature of the core and the preheating temperature of the fiber molded body are set to be substantially the same in the range of 50 to 300 ° C., and then the molten metal is injected into the mold. Then, the molten metal is pressed to fill the fiber molded body to obtain the fiber-reinforced composite.

(2) Action When the above-mentioned temperature gradient is generated in the fiber molded body, the temperature of the fiber molded body becomes relatively lower than the hot water temperature.
The molten metal can be compressed into the fiber molded body substantially uniformly from the outer peripheral surface in the circumferential direction while compressing the fiber molded body with the molten metal, whereby partial damage of the fiber molded body can be prevented. Further, since the molten metal filled in the fiber molded body is solidified from the core side toward the outer peripheral surface side,
The final solidified portion does not occur in the fiber molded body, which can prevent the occurrence of microporosity in the fiber reinforced composite.

(3) Examples FIGS. 1 to 3 show a Siamese type cylinder block S made of fiber reinforced aluminum alloy, and the cylinder block S is a plurality of cylinder barrels arranged in series, four cylinder barrels in the illustrated example.
1 ₁ to 1 ₄ combines comprising Siamese cylinder barrel 1
And an outer wall portion 2 surrounding the Siamese cylinder barrel 1, and a crankcase 3 connected to the lower edge of the outer wall portion 2.
Composed of and. Around the cylinder bore ₄ in each of the cylinder barrels 1 ₁ to 14 is composed of a cylindrical fiber-reinforced composite Cf.

A water jacket 6 facing the outer circumference of the Siamese cylinder barrel 1 is formed between the Siamese cylinder barrel 1 and the outer wall portion 2. At the cylinder head side end of the water jacket 6, the Siamese cylinder barrel 1 and the outer wall 2
The plurality of reinforcing deck parts 8 are partially connected to each other, and the adjacent reinforcing deck parts 8 have a communication port 7 to the cylinder head side.
Function as. As a result, the cylinder block S is constructed as a closed deck type.

5 to 8 show the cylinder block material Sm shown in FIG.
1 shows a casting apparatus used for practicing the present invention for casting a mold, the apparatus including a mold M as a mold, and the mold M
Is an upper mold 9 that can be raised and lowered, and is arranged below the upper mold 9,
In FIGS. 5 and 6, the first and second side molds 10 are divided into left and right parts.
₁ , 10 ₂ and left and right in FIG. 7 are divided into third and fourth side molds 10 ₃ and 10 ₄ and a lower mold 11 on which each side mold 10 ₁ to 10 ₄ is slidably mounted. To be done.

On the lower surface of the upper mold 9, a mold clamping recess defining a first cavity C ₁ for molding the Siamese cylinder barrel 1 and the outer wall part 2 in cooperation with the upper half of each side mold 10 ₁ to 10 _4. 12 are formed, and the mold clamping projections 13 that fit into the recesses 12 are formed on each side mold.
It is projected on the upper surface of 10 ₁ to 10 ₄ .

As shown in FIGS. 7 and 8, the lower mold 11 has a melting furnace (not shown).
Further, a hot water reservoir 14 for receiving molten aluminum alloy, a hot water supply cylinder 15 communicating with the hot water reservoir 14, a plunger 16 slidably fitted in the hot water supply cylinder 15, and a hot water reservoir 14 branched into two. A pair of runners 17 extending in the longitudinal direction of the one-cavity C ₁ and over substantially the same length as the one-cavity C ₁ are provided.
Further, the lower die 11 has a forming block 18 projecting upward between both runners 17, and the forming block 18 has each side die 10 ₁ to 10 ₄
Cooperates with the lower half of the lower part to define a second cavity C ₂ for forming the crankcase 3. The upper end of the cavity C ₂ communicates with the first cavity C _1, and the lower ends on both sides communicate with both runners 17 via a plurality of weirs 19.

The forming block 18 is a tall 4 formed at predetermined intervals.
Individual kamaboko-shaped first forming parts 18 ₁ and adjacent first forming parts 18 ₁
It is composed of convex second molding parts 18 ₂ located outside both the first and second outermost molding parts 18 ₁ , and each of the first molding parts 18 ₁ includes a crank pin and a crank arm rotation space 20 (second, Third
The second molding part 18 ₂ is used for molding the bearing holder 21 (FIGS. 2 and 3) of the crank journal. Each weir 19 is provided corresponding to each second molding portion 18 ₂ so that the molten metal can be injected into a large capacity portion of the second cavity C _{2 at} an early stage.

The bottom surface of the runner 17 is formed in a staircase shape of several steps from the side of the hot water reservoir 14 so that the cross-sectional area of both runners 17 gradually decreases from the side of the hot water reservoir 14 toward the runner tip 17a. Each rising portion 17c connected to each step portion 17b is formed obliquely so that the molten metal can be smoothly guided to each weir 19.

When the cross-sectional area of the runway 17 is gradually reduced in this way, a large amount of molten metal is injected into the second cavity C ₂ through the weir 19 at a slow speed in a large cross-sectional area and a small amount in a small cross-sectional area. it is possible to through weir 19 of the molten metal at a faster rate injected into the second cavity C _2, the cavity C ₂
Molten metal is poured into the inside of the runner 17 substantially evenly.
Therefore, the molten metal does not cause a turbulent flow in the cavity C ₂ , and it is possible to prevent gas such as air from being caught in the molten metal and avoid the formation of cavities. Further, since the molten metal injection work is efficiently performed, the casting efficiency can be improved.

As shown in FIGS. 5 and 6, a positioning protrusion 22 is formed on the top surface of each first molding portion 18 ₁ to which a lower end portion of a fiber molded body described later is fitted, and a recess is formed at the center of the positioning protrusion 22. 23 is formed. Further, through holes 24 penetrating the first molding portion 18 ₁ are formed on both sides of the positioning protrusion 22 in the two first molding portions 18 ₁ located on both sides, and a pair of temporary setting pins 25 are respectively formed in the through holes 24. Be slid together. These temporary setting pins 25 are used for temporary setting of a sand core for a water jacket described later. The lower ends of both temporary setting pins 25 are fixed to a mounting plate 26 arranged below the molding block 18. Two support rods 27 are inserted through the mounting plate 26, and a coil spring 28 is contracted between the lower portion of each support rod 27 and the lower surface of the mounting plate 26. When the mold is opened, the mounting plate 26 receives the elastic force of each coil spring 28 and ascends until it comes into contact with the stopper 27a at the tip of each support rod 27, whereby the tip of each temporary installation pin 25 is made into the first molding portion 18 _1.
It protrudes from the top surface. A recess 25a that engages with the lower edge of the sand core is formed on the tip surface of each temporary installation pin 25.

The two through holes 2 are formed in the two first molding portions 18 ₁ located on both sides.
In bisecting position between 4 first mold portion 18 _first through hole 29 that penetrates the is formed, actuating pin 30 which is fixed to the lower end to the mounting plate 26 into the through-hole 29 is engaged slidably. When the mold is opened, the tip of the actuating pin 30 projects into the recess 23, and when the mold is closed, it is pushed down by a cylinder bore molding core, which will be described later, so that both temporary setting pins 25 are pulled in from the top surface of the first molding portion 18 ₁ . It is like this.

First cavity C ₁ in the first and second side molds 10 ₁ and 10 ₂
Two core holders 31 for permanently installing the sand core are provided at the center of the wall defining the core. Each core receiver 31 includes an engagement hole 31a for positioning the sand core, and a sandwiching surface 31b formed on the outer circumference of the opening for sandwiching the sand core.

In the mold clamping recess 12 of the upper mold 9, a plurality of third cavities C _{3 for} communicating with the first cavity C ₁ to overflow the molten metal and a fourth cavity C ₄ for forming the communication port 7 are formed.
, And gas vent holes 32, 33 communicating with the third cavity C ₃ and the fourth cavity C ₄ are formed in the upper mold 9.

Closing pins 34 and 35 are loosely inserted into the gas vent holes 32 and 33, respectively, and upper ends of the closing pins 34 and 35 are fixed to a mounting plate 36 disposed above the upper die 9.

Small diameter portions 32a, 33a extending upward from the communicating ends of the respective gas vent holes 32, 33 with respect to the cavities C ₃ , C ₄ over a predetermined length.
Is fitted with the lower end of each closing pin 34, 35 and the third cavity C
₃ and a fourth cavity C ₄ and is able to close.

A hydraulic cylinder 39 is interposed between the top surface of the upper die 9 and the mounting plate 36, and the mounting plate 36 is moved up and down by the operation of the hydraulic cylinder 39 to open and close the small diameter portions 32a, 33a by the closing pins 34, 35. It is like this. 40 is a guide rod for the mounting plate 36.

On the top surface of the mold clamping recess 12 of the upper mold 9, each cylinder barrel 1 ₁ ~
A cylindrical core 41 for forming a cylinder bore is provided so as to face upward and downward in correspondence with the number 1 to ₄ , and a first core is formed on the lower end surface of each core 41.
A convex portion 41a that can be fitted into the concave portion 23 on the top surface of the molding portion 18 ₁ is provided. Further, a heater h is embedded in the core 41, and the heater h
Thus, the core 41 can be heated to a predetermined temperature.

FIGS. 9 and 10 show a sand core 59 for a water jacket, which sand core 59 has four cylinder barrels 1 of the cylinder block S _1.
Core body 61 having _four cylindrical portions 60 _{1 to} 60 ₄ corresponding to ~ 1 ₄ and lacking peripheral walls where adjacent ones overlap each other, and a water jacket as a water jacket of a cylinder head. A plurality of projections 62 projecting from the upper end surface of the core body 61 to form the communication port 7 and the reinforcing deck portion 8 that communicate with each other;
The two cylindrical parts 60 ₂ and 60 ₃ located in the middle are constituted by skirting boards 63 which are respectively provided on both outer side surfaces. Each skirting board 63 is formed of a large-diameter portion 63a integral with the core body 61 and a small-diameter portion 63b projecting from the end surface thereof.

FIG. 11 shows a cylindrical fiber molded body F molded from a mixed fiber of carbon fiber and alumina fiber, the size of which is 89 mm in outer diameter.
mm, inner diameter 78 mm, height 152 mm, its bulk density is 0.3-1.2 g
/ cm ³ . The fiber molded body F includes carbon fibers (short fibers) having an average diameter of 18 μm and an average length of 0.8 mm, and an average diameter of 3 to 4 μ.
m and an alumina fiber (short fiber) having an average length of 0.5 mm were mixed at a ratio of 1: 3, silica sol was added to the mixed fiber as a binder, and the mixture was molded by a suction adhesion molding method. In this case, an alumina sol simple substance or a mixture of silica sol and alumina sol can be used instead of the silica sol.

The suction adhesion molding method, in a tank containing a mixture of the mixed fiber and silica sol, standing up a breathable cylindrical mold with both end surfaces sealed, and applying a suction action to the inside of the cylindrical mold, It means a method of adsorbing the mixture on the outer peripheral surface of the cylinder.

The fiber molded body molded by the above-mentioned method is used after being subjected to a drying process and a firing process after releasing from the mold.

Next, a casting operation of the cylinder block material Sm by the casting apparatus using the fiber molded body F will be described.

First, as shown in FIG. 5, the upper mold 9 is raised, and the opposite molds 10 ₁ , 10 ₂ ; 10 ₃ , 10 ₄ are moved so as to be separated from each other to open the mold. The hydraulic cylinder 39 on the upper die 9 is operated to raise the closing pins 34, 35 via the mounting plate 36,
Third, the small-diameter portion 32a which communicates with the fourth cavity C _3, C _4, open each upper opening of 33a. Furthermore, the plunger in the hot water supply cylinder 15
Lower 16

Each fiber molded body F preheated to about 300 ° C. is fitted to each core 41 heated to about the same temperature, and the upper end opening of the fiber molded body F is brought into contact with the top surface of the recess 12 of the upper die 9. .

At this point, the temperature gradient of the core 41 and the fiber molded body F is
As shown by the line x in FIG. 12 (a), it is substantially zero.

As shown in Figs. 5 and 10, the cylindrical parts on both sides of the sand core 59
The lower edges of 60 ₁ and 60 ₄ are engaged with the recesses 25a of the temporary setting pins 25 projecting to the top surfaces of the first molding portions 18 ₁ on both sides of the lower mold 11 to temporarily install the sand core 59.

As shown in FIG. 6, the two-sided molds 10 ₁ and 10 ₂ are moved by a predetermined distance in the direction in which they approach each other, and each core support 31 and each skirting board is moved.
The sand core 59 is permanently installed by engaging with 63. That is, the small diameter portion 6 of each skirting board 63 in the sand core 59 is inserted into the engagement hole 31a of each core support 31.
3b is fitted to position sand core 59, and each large diameter part 63a
The end faces parallel to the cylinder barrel arrangement direction of the above are abutted against the sandwiching faces 31b of each core receiver 31 to sandwich the sand core 59 by these sandwiching faces 31b. The other two-sided molds 10 ₃ and 10 ₄ are also moved in the same manner.

Next, the upper die 9 is lowered, each fiber molded body F is inserted into each cylindrical portion 60 _{1 to} 60 ₄ of the sand core 59, and the lower end portion of each fiber molded body F is fitted to the positioning projection 22. The convex portion 41a of the core 41 is fitted into the concave portion 23 on the top surface of the first molding portion 18 ₁ . Since the operating pin 30 is pushed down by this concave-convex fitting, each temporary setting pin 25 descends and is retracted from the top surface of the first molding portion 18 ₁ . See again Sunako 59
Each projection 62 is loosely inserted in each fourth cavity C _4, and the mold clamping concave portion 12 of the upper mold 9 is further provided with the mold clamping convex portion of each side mold 10 ₁ to 10 _4.
It is fitted to 13 and the mold is clamped.

A molten metal consisting of aluminum alloy (JIS ADC12) at 730 to 740 ℃ is supplied from the melting furnace to the hot water reservoir 14 of the lower mold 11, and the puangier 16 is raised at a speed of 0.08 to 0.3 m / sec, as shown in FIG. As described above, the molten metal is injected from both runways 17 through the weir 19 into the cavities C ₂ and the first cavities C ₁ from the lower portions of the second cavities C ₂ with the pressure p ₁ . Gases such as air in both cavities C ₁ and C ₂ are pushed up by the molten metal and escape above the upper mold 9 through the gas vent holes 32 and 33 communicating with the third and fourth cavities C ₃ and C ₄ .

In this case, the cross-sectional area of both runways 17 is the runway tip 17a as described above.
The bottom of the runner is
Since it is formed in a staircase shape with several steps from the side, the molten metal is made evenly from the both runways 17 through each weir 19 to the second cavity C ₂ by the rise of the plunger 16 and from its lower parts to its entire length. Injected.

Further, since the openings of the small diameter portions 32a, 33a of the gas vent holes 32, 33 are narrow, when pouring the molten metal into the first and second cavities C ₁ , C _{2, the} inside of the cavities C ₁ , C ₂ A back pressure is generated in the back surface, and the back pressure acts evenly on the entire surface of the molten metal. As a result, the surface of the molten metal is suppressed from waviness and rises substantially horizontally, which prevents gas from being entrained in the molten metal and efficiently degass the molten metal, thus avoiding the formation of cavities. Due to the back pressure,
The injection pressure of the molten metal in the first and second cavities C ₁ and C ₂ is
As shown in FIG. 13, pressure p ₁ above atmospheric pressure, for example 2 to
It becomes 5 kg / cm ² .

Further, since the fiber molded body F is preheated to the above temperature,
The molten metal around the fiber molded body F is kept warm, so that the molten metal is prevented from adhering to the fiber molded body F.

When the molten metal is completely poured into the third and fourth cavities C ₃ and C ₄ , the hydraulic cylinder 39 on the upper die 9 is operated to attach the mounting plate 36.
And lower the cavities C ₃ and C ₄ with the closing pins 34 and 35.
The small diameter portions 32a, 33a communicating with the are closed.

After that, the plunger 16 is raised at a speed of 0.14 to 0.18 m / sec to melt the molten metal under a high pressure p ₂ above the pressure p ₁ , that is, 5400.
The fiber-reinforced composite Cf is obtained by maintaining it under a pressure of kg / cm ^{2 for} a predetermined time, and the molten metal is completely solidified under this high pressure to densify the structure of the aluminum alloy and improve its strength. In the process of increasing the pressure of the molten metal, the pressure of the molten metal is 5 to 20 kg / cm ²
The molten metal is filled in the fiber molded body F. Since the filling pressure of the molten metal is low as described above, the fiber molded body F is not destroyed by the molten metal during filling.

When molten metal is injected into the first cavity C ₁ , FIG. 12 (a)
In the above, as shown by the line y, a temperature gradient is generated in the fibrous molded body F, which rapidly and substantially linearly drops from the outer peripheral surface side in contact with the molten metal Ma to the inner peripheral surface side in contact with the core 41. Therefore, the temperature becomes relatively low with respect to the temperature of the fiber molded body F, and as a result, the molten metal Ma compresses the fiber molded body F, and the fibrous material is filled into the hot water molded body F substantially uniformly in the circumferential direction from the outer peripheral surface thereof. It This prevents the fiber molded body F from being partially damaged.

Further, since the molten metal filled in the fiber molded body F is solidified from the core 41 side toward the agent peripheral surface side due to the temperature gradient, the final solidified portion does not occur in the fiber molded body F. As a result, a fiber-reinforced composite Cf free of microporosity is obtained.

Since the sand core 59 is sandwiched by the _two side molds 10 ₁ and 10 _{2 at the} correct positions through the respective skirting boards 63 of the sand core 59, the first cavity
Never sand core 59 or lifted at the injection time and pressing time of the molten metal in the cavity C in the _first molten metal into C _1. The double-sided 10 the end surface of the large diameter portion 63a of the skirting 63 _1, 10 ₂
Since the sand core 59 abuts against the sandwiching surface 31b of the core receiver 31 in the above, when the sand core 59 tends to swell, its deforming force is
The sand core 59 is supported by b, so that the deformation of the sand core 59 is prevented, and the Siamese cylinder barrel 1 having a uniform wall thickness around each cylinder bore 4 is obtained.

When the mold is opened after the molten metal is solidified, the cylinder block material Sm shown in FIG. 4 is obtained.

Grinding the cylinder block material Sm to make each
When the protrusions 64 formed by the cooperation of the cavity C ₄ and the protrusions 62 of the sand core 59 are removed, the protrusions 62 allow the communication port 7 to move.
However, the reinforcing deck portions 8 are formed between the communication ports 7 adjacent to each other, and the water jacket 6 is formed by sand removal.
When the inner peripheral surface of each cylinder bore 4 is subjected to perfect circle processing, and further other predetermined processing is performed,
The cylinder lock S shown in FIG. 3 is obtained.

FIG. 12 (b) shows the conventional method, in which the preheating temperature of the fiber molded body F is set higher than the heating temperature of the core 41, that is, the line x ₂ as shown by the line x ₁ . When such a temperature setting is performed, when the molten metal is poured into the mold, a portion y ₁ that gently falls on the outer peripheral surface that contacts the molten metal and the vicinity thereof is generated in the temperature gradient generated in the fiber molded body F, and as a result, The casting defect as described above occurs in the region z corresponding to the portion.

In the present invention, the heating temperature of the core 41 and the preheating temperature of the fiber molding F are optimally in the range of 50 to 300 ° C. When the temperature is lower than 50 ° C., the amount of heat retained in the core 41 and the fiber molded body F decreases and the temperature of the molten metal lowers, so that there is a portion where the molten metal is not filled in the fiber reinforced composite Cf. 300
When the temperature exceeds ℃, the heat retention amount of the core 41 and the fiber molded body F increases, and the final solidified portion of the molten metal occurs in the fiber molded body F,
Microporosity is generated in the fiber-reinforced composite Cf.

The fiber molded body F may be molded from one type of reinforcing fiber, and as the matrix, cast iron, copper, magnesium alloy or the like is used in addition to the aluminum alloy.

C. Effect of the Invention According to the present invention, by setting the heating temperature of the core and the preheating temperature of the fiber molded body to be substantially the same in the range of 50 to 300 ° C., the outer peripheral surface of the fiber molded body that contacts the molten metal Since a temperature gradient that rapidly and substantially linearly drops from the side toward the inner peripheral surface contacting the core is generated, the molten metal can be substantially uniformly filled from the outer peripheral surface of the fiber molded body in the circumferential direction. This makes it possible to prevent partial damage of the fiber molded body. Further, since the molten metal filled in the fiber molded body is solidified from the core side toward the outer peripheral surface side, a final solidified portion does not occur in the fiber molded body, which causes generation of microporosity in the fiber reinforced composite. Can be prevented.

Therefore, by adopting the above method, it is possible to obtain a fiber-reinforced cylinder block material provided with a fiber-reinforced composite body in which no casting defects occur.

[Brief description of drawings]

1 to 3 show a Siamese type cylinder block made of the material obtained by the present invention, FIG. 1 is a perspective view seen from above, FIG. 2 is a sectional view taken along line II-II of FIG. Fig. 2 is a sectional view taken along line IIa-IIa of Fig. 2, Fig. 3 is a perspective view seen from below, and Fig. 4 is a perspective view seen from above of a Siamese type cylinder block material obtained by the present invention. FIG. 6 is a vertical sectional front view of the casting apparatus when the mold is opened, FIG. 6 is a vertical sectional front view of the casting apparatus when the mold is closed, FIG. 7 is a sectional view taken along line VII-VII of FIG. 6, and FIG. 8 is FIG. -VIII line sectional view, FIG. 9 is a perspective view of the sand core seen from above, FIG. 10 is a sectional view taken along line XX of FIG. 9, FIG. 11 is a perspective view of a fiber molding, and FIG. 12 is FIG. 13 is an explanatory view showing the temperature gradient in the fiber molded body, and FIG. 13 is a graph showing the relationship between the molten metal pressure and time. Cf: Fiber reinforced composite, F: Fiber molded body, M: Mold as mold, Ma ... Molten metal, Sm: Fiber reinforced Siamese type cylinder block material, 4 ... Cylinder bore

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Claims (1)

[Claims] 1. When casting a fiber reinforced cylinder block material composed of a tubular fiber reinforced composite (Cf) around a cylinder bore (4), a cylinder is formed in a cylinder bore molding core (41) of a mold (M). When the fiber molded body (F) is fitted and the molten metal (Ma) is poured into the mold (M), the fiber molded body (F) is contacted with the molten metal (Ma) from the outer peripheral surface side to the core. The heating temperature of the core (41) and the preheating temperature of the fiber molded body (F) are set so as to generate a temperature gradient that drops sharply and substantially linearly toward the inner peripheral surface contacting with (41). To 50
To about 300 ° C., the molten metal is poured into the mold (M), and then the molten metal (Ma) is pressed to fill the fiber molded body (F) and the fiber-reinforced composite. A method for casting a fiber-reinforced cylinder block material, which comprises obtaining a body (Cf).