JPH10263791A - Preliminary formed body for composite structure, core member held thereby, and manufacture of composite metal parts of the core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a core member from being cracked by providing a preliminary formed body so as to provide a gap between the preliminary formed body and the core member at the part other than a core holding part, and projecting the core holding part in a part of a preliminary formed body base part to reduce the thermal stress generated in the core member during the casting even when the coefficient of thermal expansion of the core member and the preliminary formed body is large. SOLUTION: A preliminary formed body B for composite structure is provided with a ring-shaped preliminary formed body base part 30 and three core holding parts 31 projected in a part of an inner circumferential part of the base part 30. Three core holding parts 31 are provided in the circumferential direction approximately with equal intervals, and an inclined surface whose projection becomes smaller downward is formed on a tip surface of each core holding part 31. A ring-shaped salt core C whose outside diameter is smaller than the inside diameter of the formed body B and which forms an oil passage for cooling is press-fitted to each inclined surface, and the salt core C is held by each core holding part 31 of the formed body B. The base part 30 is formed to have a gap between the salt core C and the base part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite preform, a core member held by the preform, and a method of manufacturing a composite metal part in which the preform is composited. It belongs to the technical field of structure.

[0002]

2. Description of the Related Art Conventionally, in order to reinforce only a portion where strength and wear resistance are required, for example, Japanese Patent Publication No. 2-30790.
As disclosed in Japanese Patent Application Laid-Open Publication No. Hei 2-62776 and Japanese Patent Publication No. 2-62776, a method is known in which a composite material is partially composited with a reinforcing material composed of metal such as nickel or its fiber, or ceramic fiber or particles. In this method, a preformed body having pores therein is prepared in advance by using the above-described reinforcing material, and a high-pressure casting method of applying a high pressure to a molten aluminum alloy filled in a mold by a pressure punch, a plunger, or the like is used. The molten metal is impregnated into the pores of the preformed body to form a composite of the preformed body and the aluminum alloy.

Further, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-290227, as a normal casting method without using a preform, molten metal in a mold is used to prevent casting defects such as shrinkage cavities. It is known to pressurize with gas.

On the other hand, conventionally, when a composite metal part has a shape that cannot be directly formed only by a mold, for example, when a cooling oil passage is provided inside a piston for an automobile engine, a salt in salt It is known to use a collapsible core member such as a core or a sand core. In this case, usually, a fine hole is formed in the core member, and the hole is fitted into a projection formed in the mold, or a pin is penetrated in the hole, and the tip of the pin is formed in the mold. Or the like, the core member is held in the mold.

However, as described above, when the molten metal and the preform are compounded by pressurizing the molten metal, the above-described method of holding the core member requires the pressurization of the hole formed in the core member by pressing. The molten metal penetrates into the pin insertion holes provided in the mold and the mold and solidifies, so that the mold is difficult to separate from the core member.
Further, even if the core member is separated, there is a problem that the core member cannot be held in the mold when performing the next casting because the solidified molten metal remains in the protrusions or the pin insertion holes of the mold.

Therefore, as shown in, for example, Japanese Patent Application Laid-Open No. Sho 60-13955, the entire outer periphery of the ring-shaped core member is fitted around the entire inner periphery of the ring-shaped preform. It has been proposed that the core member be held on the preform by an inorganic binder.

Further, as disclosed in Japanese Patent Application Laid-Open No. 8-158934, a half-split type FR for holding a core is disclosed.
It has been proposed to provide an M member, hold the core on the core holding FRM member, and also hold the preformed body on the outer periphery thereof.

[0008]

However, in the holding method of the latter proposed example (Japanese Patent Laid-Open No. 8-158934), the cost is increased because many expensive FRM members are used, and the space for the FRM members is reduced. There is a problem that the degree of freedom in design is reduced due to the extra necessity.

Further, the former proposed example (Japanese Patent Application Laid-Open No. Sho 60-1)
No. 3955), when the thermal expansion coefficient of the core member is larger than that of the preformed body, the deformation of the core member is restrained by the preformed body. Cracks occur in the core member, and the molten metal penetrates into the cracks to easily generate burrs.

[0010] Further, in either of the proposed examples, the portion of the preform to be impregnated with the molten metal is limited by the core member or the FRM member. Problem.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to hold a core member directly on a preformed body as described in the former proposed example, and pressurize the molten metal by pressurizing. When compounding with a molded body, by improving the holding structure of the core member, even when the difference in thermal expansion coefficient between the core member and the preformed body is large, the thermal stress generated in the core member during casting can be reduced. Another object of the present invention is to reduce the core member in order to prevent the core member from cracking and to easily impregnate the molten metal into the preformed body to improve the composite property between the molten metal and the preformed body.

[0012]

In order to achieve the above object, according to the present invention, a composite preform having a core holding portion for holding a core member is provided with a core member. The preform base was formed so as to have a gap therebetween, and the core holding portion was provided so as to project from a part of the preform base.

More specifically, in the first aspect of the present invention, the preform for compounding is formed by pressurizing a molten metal filled in a mold and having a core holding portion for holding a core member. Assume the body.

A preformed base is formed so as to have a gap between the core and the core member, and the core holding portion is provided so as to project from a part of the preformed base. Shall be.

Thus, since the preformed body is formed so as to have a gap between the core member and the core member at a position other than the core holding portion, the heat of the core member and the preformed body is formed. Even when the expansion coefficient difference is large, the core member or the preformed body can be expanded and deformed without being restrained by the counterpart member by the gap, thereby reducing the thermal stress generated in the core member during casting. it can. In addition, since the molten metal is impregnated into the preformed body from a portion of the gap other than the core holding portion, a portion where the molten metal can be impregnated into the preformed body can be increased. Therefore, it is possible to prevent the core member from cracking due to thermal stress and suppress the generation of burrs, and to improve the composite property between the molten metal and the preform.

According to a second aspect of the present invention, in the first aspect of the present invention, the preform base has a ring shape, and a plurality of core holding portions are circumferentially defined on an inner peripheral portion of the preform base. It is assumed that they protrude in the radial direction with an interval.

[0017] Thus, the core member is also formed in a ring shape, so that the core member can be held in a well-balanced manner.
Thermal stress generated in the core member can be uniformly dispersed. Further, since the coefficient of thermal expansion of the core member is generally larger than that of the preformed body, the holding structure is particularly suitable for holding the core member on the inner peripheral side of the preformed body. Therefore, an optimal structure for holding the core member can be obtained.

According to a third aspect of the present invention, in the first or second aspect of the invention, the core holding portion has a higher porosity than the base of the preformed body.

According to the present invention, the core holding portion itself of the preformed body is easily deformed, so that the thermal stress generated in the core member can be further reduced. Therefore, cracking of the core member due to thermal stress can be more effectively suppressed.

According to the fourth aspect of the present invention, the first, second or third aspect of the invention is provided.
In the present invention, the core holding portion is softer than the base of the preformed body.

With this configuration, the thermal stress of the core member can be further reduced by the deformation of the core holding portion. Therefore, the same function and effect as the third aspect of the invention can be obtained.

According to a fifth aspect of the present invention, in the first, second, third or fourth aspect of the present invention, the core holding portion is made of a member different from the base of the preformed body.

This makes it possible to increase the degree of freedom of the shape and the material of the core holding portion, and the core holding portion which does not require abrasion resistance or the like can be used at a high cost such as used for the base of the preform. There is no need to use materials. Therefore, cracking of the core member due to thermal stress can be prevented while reducing the cost for forming the core holding portion.

The invention according to claim 6 is based on the premise that the core member is provided with a holding portion which is held by the composite preform formed by pressing the molten metal filled in the mold.

A core member base is formed so as to have a gap between the core preform and the holding member, and the holding portion is provided so as to project from a part of the core member base. It shall be. This is the same as the first aspect of the present invention except that the core member has the holding portion projecting therefrom. Therefore, the same function and effect as the first aspect of the invention can be obtained.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the core member base has a ring shape, and the plurality of holding portions are spaced at a predetermined interval in the circumferential direction at the outer peripheral portion of the core member base. It is assumed that it protrudes in the radial direction in a state where it is set.
Thus, the same function and effect as the second aspect of the invention can be obtained.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, the core member is a salt core.

By doing so, the thermal expansion coefficient of the salt core is considerably higher than that of the preformed body, so that the value of adopting the holding structure according to the sixth or seventh aspect of the invention becomes high. Therefore, effective use of the core member holding structure can be achieved.

According to a ninth aspect of the present invention, there is provided a method of manufacturing a composite metal part. In this invention, a preform for composite formed by pressurizing a molten metal charged in a mold and the composite preform are provided. The core member held by the preform for molding is protruded from a base formed so as to have a gap with respect to the mating member, and a part of the base of at least one of the preform for composite and the core member. The composite preform is supported in a mold in a state where the core member is held in the composite preform by the holding part, and Is filled with a melt and pressurized to form a composite with the composite preform.
According to this invention, the same function and effect as those of the first or sixth invention can be obtained.

According to a tenth aspect of the present invention, in the ninth aspect of the present invention, the molten metal in the mold is pressurized with a gas in a state where the molten metal is filled into the mold from the gate of the mold and the molten metal is closed.

In this way, unlike the high-pressure casting method, the molten metal and the preform can be combined with a relatively low pressing force, so that the core member is made of a collapsible salt core, sand core, or the like. In this case, it is possible to easily and reliably prevent the core member from being damaged or deformed by pressure during casting. Therefore, when the preform and the molten metal are combined while the core member is held in the preform, an optimal casting method can be obtained.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIGS. 1 and 2 show a preform B for compounding according to Embodiment 1 of the present invention.
Is a piston 1 for an automobile engine as shown in FIG.
It is used when manufacturing. This piston 1
A top ring groove 3 for fitting a top ring, a secondary groove 4 for fitting a secondary ring, and an oil ring for fitting an oil ring The grooves 5 are formed respectively. The piston 1 is made of an aluminum-based metal (AC8A specified in JIS H5202).
Etc.) as a base material, and only the periphery of the top ring groove 3 is an aluminum-based composite metal component having a composite portion 6 which is composited with the aluminum-based metal and a reinforcing material of a nickel-chromium alloy. A ring-shaped cooling oil passage 8 is formed inside the piston 1 inside the composite portion 6. In FIG. 3, reference numeral 7 denotes a piston pin insertion hole for inserting a piston pin for connecting the piston 1 to the connecting rod.

The preformed body B is in a state before the composite portion 6 of the piston 1 is composited with an aluminum-based metal and has pores (porosity of about 80 to 95%).
It is made of a porous metal body. Then, as described later, the preform B is impregnated into the pores of the preform B by being pressurized with the molten metal of the aluminum-based metal to be composited. The outer diameter of the preformed body B is larger than the outer diameter of the piston 1, and a groove corresponding to the top ring groove 3 is not formed on the outer peripheral portion thereof. By subjecting the casting 9 (see FIG. 13) in which the body B and the aluminum-based metal melt are compounded to mechanical cutting, a predetermined piston shape is obtained.

The preform B has three core holders 31, 31,... Protruding radially inward from a ring-shaped preform base 30 and a part of the inner periphery of the base 30. And The three core holders 31, 31,...
The core holding portions 31 are provided at substantially equal intervals in the circumferential direction.
As shown in FIG. 2, inclined surfaces 31 a of which the protruding amount decreases toward the lower side are respectively formed on the distal end surfaces. Each of the inclined surfaces 31a has an outer diameter smaller than the inner diameter of the preformed body B, and a ring-shaped salt core (core member) C for forming the cooling oil passage 8 is placed on the lower side. It is possible to press-fit the fitting. Thus, the salt core C is held by each core holding portion 31 of the preformed body B, and the base 30 has a gap between the salt core C and the held salt core C. It is formed as follows. The coefficient of thermal expansion of the salt core C is considerably larger than that of the preform B.

FIGS. 4 and 5 show a manufacturing apparatus A for manufacturing the piston 1. The manufacturing apparatus A is divided into two side molds 12 which are substantially symmetrical with respect to their mating surfaces 12a. , 12 and an upper die 13 and a middle die 14 respectively inserted into an upper die insertion hole 18 and a middle die insertion hole 19 formed in a state where the two side dies 12, 12 are joined together at respective mating surfaces 12a. It has a mold 11. A space surrounded by these molds 12 to 14 in a state where the both molds 12 and 12 are fitted together at each mating surface 12a and the upper mold 13 and the middle mold 14 are completely inserted (mold clamped state). Is formed into a product cavity 15 having substantially the same shape as the piston 1 (the casting 9 before cutting), and the casting 9 is cast by filling the product cavity 15 with a molten metal of an aluminum-based metal. I have. The upper mold 13 and the middle mold 14 are arranged vertically,
Each of the molds 2 and 12 is configured to be slidable in a direction (perpendicular to the plane of FIG. 4) perpendicular to the respective mating surfaces 12a. When the casting is completed, the molds 12 to 14 are slid (mold opened) in a direction away from each other. It has become. In FIG. 4,
Reference numeral 17 denotes a cast pin for forming the piston pin insertion hole 7.

The mold 11 has a product cavity 15
The preform B can be supported therein while holding the salt core C. That is, steps 12b, 12b are respectively formed above the product cavities 15 in both side molds 12, 12 of the mold 11, and the inside diameter above each step 12b is the same as the inside diameter of the upper mold insertion hole 18. The outer diameter of the preformed body B is slightly larger than the outer diameter of the preformed body B.
Is smaller than the outer diameter of Thus, the preform B can be inserted from the upper die insertion hole 18 to each step 12b with the upper die 13 slid upward and separated from the side dies 12, 12. When the upper die 13 is completely inserted into the upper die insertion hole 18, the upper surface of the preformed body B inserted up to the step 12b by the tip end surface of the protruding portion 13a provided on the outer peripheral portion of the lower surface thereof. It is possible to press the preform B into the upper mold 1
3 is supported between the distal end surface of the projection 13a and the step 12b of each of the side molds 12, 12.

A sprue having a tapered surface for filling an aluminum-based metal melt into the mold 11 on the mating surface 12a of each of the two side molds 12, 12 of the mold 11 on the side of the upper mold insertion hole 18 above the mold. 26 and a runner 27 having a substantially circular cross section connecting the gate 26 and the lower part of the product cavity 15 are formed. The runner 27 extends from the gate 26 downwardly and at a substantially right angle to the product cavity 15.
It is bent to the side, extends horizontally and is connected to the product cavity 15.

Further, both side molds 12, 1 of the mold 11 are provided.
2 is provided on the opposite side of the runner 27 with the product cavity 15 therebetween, with the air vent groove 3 having a substantially rectangular cross section.
5 are formed. The air vent groove 35 is provided so as to extend in the horizontal direction from the side of the preformed body B supported as described above, and then to extend upward. When the molten metal is filled into the product cavity 15, This is for bleeding the air in the cavity 15. When the molten metal enters the air bleed groove 35, it cools and solidifies to form a seal.

The gate 26 is covered with a cover 37 which can be moved up and down above the gate 26. The cover 37 has a taper surface having substantially the same shape as the taper surface of the sprue 26 at the lower part, and the sprue 26 is completely closed by fitting the lower part thereof to the upper part of the sprue 26. I have.

A lower part in the upper die 13 of the mold 11 has a feeder portion 13b which is recessed upward from the lower surface into a substantially truncated cone shape.
Are formed. Further, one end of a pipe 38 for blowing air into the feeder portion 13b to press the molten metal in the mold 11 from the feeder portion 13b passes through the upper die 13 through the upper die 13. It is attached and fixed so as to reach the upper end of the riser 13b. The other end of the pipe 38 is connected to a pressurized air source (not shown) for producing factory air having a pressure in the range of 0.5 to 30 kgf / cm ² .

The preform B for composite having the above structure
A method of manufacturing the piston 1 by the manufacturing apparatus A while holding the salt core C in the tank will be described. First, in order to produce the preform B, as shown in FIG. 6, a substantially rectangular porous metal sheet 32 is strip-shaped into sheets 32a and 32a.
(a) in the figure, and each of the strip-shaped sheets 32a is wound in a ring shape (b). Then, the ends of the respective sheets 32a are joined to each other by press molding, and the sheets 32a are pressed down into a desired shape. At this time, the preform B is completed by simultaneously forming the core holding portions 31 by press molding (FIG. 3C).
Further, a salt core C is prepared by solidifying the salt into a ring shape by press molding (FIG. 3D), and the outer peripheral portion of the salt core C is held in each of the cores in the preformed body B. Part 3
By press-fitting into the 1 inclined surface 31a from below,
The salt core C is held in the preform B (FIG. 4E).

Then, as shown in FIG. 7, the preform B holding the salt core C is inserted into the upper mold while the upper mold 13 and the cover 37 of the mold 11 in the manufacturing apparatus A are slid upward. Insert from the hole 18 to each step 12b of both side molds 12,12. Then, as shown in FIG. 8, the upper mold 13 is inserted into the upper mold insertion hole 18, and the preform B is supported between the tip surface of the protruding portion 13a and each stepped portion 12b of both side molds 12, 12. I do. In this state, as shown in FIG. 9, the molten metal 43 of the aluminum-based metal is filled into the runner 27 and the product cavity 15 from the sprue 26 by using the reference 44.

At this time, the preformed body B and the salt core C expand due to the heat of the molten metal 43. However, since the thermal expansion coefficient of the salt core C is considerably larger than that of the preformed body B, the salt core C is preformed. The deformation of each core holding portion 31 of the body B is restricted. However, since a gap is formed between the core 30 and the base 30 of the preform B at a location other than each core holding portion 31, the salt core C expands and deforms at that location, and The thermal stress generated in the child C can be reduced to prevent the crack.

Next, when the molten metal 43 has been filled in the runner 27, that is, when the molten metal 43 has been filled to the substantially vertical center of the feeder portion 13b of the upper mold 13 (see FIG. 10), as shown in FIG. Then, the cover 37 is slid downward to close the gate 26 with the cover 37.

Subsequently, as shown in FIG. 12, factory air is supplied from the pressurized air source to the feeder portion 13b of the mold 11 via the pipe 38 to press the molten metal 43 in the mold 11. Thus, the molten metal 43 is impregnated in the preform B, and the molten metal 43 and the preform B are composited. At this time, the molten metal 43 is impregnated into the preformed body B also from the gap between the preformed body B and the salt core C.
The impregnation into the preform B of No. 3 is hardly limited by the salt core C. In addition, since the pressurization of the molten metal 43 is performed at a considerably lower pressure than in the high-pressure casting method, breakage and deformation of the salt core C due to the pressurization can be easily and reliably prevented.

After the molten metal 43 is continuously pressed under pressure for a while, the molten metal 43 is cooled and solidified. afterwards,
While sliding the cover 37 upward, the upper mold 1
3. The mold 14 is opened by sliding the middle mold 14 and both side molds 12 and 12, respectively.
Take out from inside. At this time, as shown in FIG. 13, in the casting 9, the top ring groove 3, the secondary ring groove 4, and the oil ring groove 5 were not formed, and the outer peripheral portion of the preform B was protruded from the periphery. In state. This casting 9
Is subjected to T6 heat treatment, and then subjected to mechanical cutting.
That is, the entire outer peripheral portion of the casting 9 is cut, and then the top ring groove 3, the secondary ring groove 4, and the oil ring groove 5 are formed by cutting. Further, a hole is drilled from the lower side of the casting 9 to the location of the salt core C, and water is supplied to the hole to dissolve the salt core C in the water, thereby forming the cooling oil passage 8. Thus, the piston 1 having the composite portion 6 around the top ring groove 3 is completed. In the cooling oil passage 8 of the completed piston 1, no burrs are generated since the salt core C does not crack during casting.

Therefore, in the first embodiment, each core holding portion 31 of the preformed body B has an inner periphery in the ring-shaped preformed base 30 formed so as to have a gap between the core and the salt core C. Of the core holding portions 31 are protruded from a part of the cores at substantially equal intervals in the circumferential direction.
Since the outer periphery of the ring-shaped salt core C is held at
Even when the salt core C having a larger coefficient of thermal expansion than the preformed body B is held inside the preformed body B, the salt core C is restrained by the preformed body B by the gap. It can be expanded and deformed without heat, and the thermal stress during casting can be dispersed uniformly. Further, due to the presence of the gap, the preformed body B of the molten metal 43 is compared with the case where the entire outer circumference of the salt core C is held at the entire inner circumference of the base 30 of the preformed body B.
The impregnable part can be increased. Therefore, cracking of the salt core C due to thermal stress can be prevented and generation of burrs can be suppressed, and the molten metal 43 and the preform B
And the optimum structure for retaining the salt core C can be obtained.

(Embodiment 2) FIG. 14 and FIG. 15 show Embodiment 2 of the present invention (in the following embodiments, the same parts as those in FIG. 1 and FIG. The detailed description will be omitted, and only different points will be described.) The configuration of each core holding portion 31 that holds the salt core C in the preform B is different from that of the first embodiment.

That is, in this embodiment, when the metal porous body sheet 32 is cut into strips and each sheet 32a wound in a ring shape is subjected to press forming, the reduction rate of each core holding portion 31 is reduced. It is made smaller than the preform base 30.
Thus, each core holding portion 31 has a higher porosity than the base portion 30 to improve the deformability, and the base portion 3
It has a shape protruding above 0.

Therefore, in the second embodiment, each core holding portion 31 of the preform B is easily deformed.
The thermal stress generated in the salt core C can be further reduced. In addition, the base 30 and each core holder 3
The porosity of each core holding portion 31 can be easily increased simply by changing the rolling reduction with respect to 1. Therefore, cracking of the salt core C due to thermal stress can be more effectively prevented with a simple configuration.

(Embodiment 3) FIG. 16 shows Embodiment 3 of the present invention, which is different from Embodiments 1 and 2 in that each core holder 31 is made of a material different from that of the base 30. That is, each core holding portion 31 is made of a material that is softer than the base 30 and is integrally formed with the base 30 by press molding.

Therefore, in the third embodiment, similarly to the second embodiment, the thermal stress generated in the salt core C due to the deformation of each core holding portion 31 can be further suppressed. Therefore, the same functions and effects as those of the second embodiment can be obtained.

In the third embodiment, each core holder 3
Although 1 is made of a soft material different from the base 30, each core holding portion 31 may be made of the same material having a different porosity from the base 30 so as to be softer than the base 30.

(Embodiment 4) FIG. 17 shows Embodiment 4 of the present invention.
And another member. That is, each core holding portion 31 is formed of a substantially U-shaped core holding member 33 in which a concave portion 33a is formed at a substantially central portion in the vertical direction, and the concave portion 33a of each core holding member 33 is preformed. Each core holding portion 31 is formed by fitting the inner periphery of the body B at substantially equal intervals in the circumferential direction. Each core holding member 33 is softer than the base 30 as in the third embodiment.

Accordingly, in the fourth embodiment, since each core holding portion 31 is constituted by the core holding member 33 which is a member different from the base portion 30, the shape and material of each core holding portion 31 are different. The degree of freedom can be increased, and it is not necessary to use an expensive material such as that used for the preform base 30 for each core holding portion 31 that does not require wear resistance or the like. Therefore, cracking of the salt core C due to thermal stress can be prevented while reducing the cost for forming each core holding part 31.

(Embodiment 5) FIG. 18 shows Embodiment 5 of the present invention, in which the preform B is not provided with the core holders 31 as in Embodiments 1 to 4, Salt core C
Are formed with holding portions 41, 41,... Held by the preform B.

That is, in this embodiment, the salt core C
Is a ring-shaped core member base portion 40 and three holding portions 4 projecting radially outward from a part of the outer peripheral portion of the base portion 40.
1, 41,... The holding portions 41 are provided at substantially equal intervals in the circumferential direction, and the distal end surface of each of the holding portions 41 is formed such that the amount of protrusion decreases upward. This allows the front end surface of each holding portion 41 of the salt core C to be pressed into the inner peripheral portion of the preform B from below and fitted therein.
Are held on the preform B by the holding portions 41.

Therefore, the fifth embodiment is exactly the same as the first embodiment except that the respective holding portions 41 are projected from the salt core C. Therefore, the same functions and effects as those of the first embodiment can be obtained.

In each of the above embodiments, the gate 26 of the mold 11 is closed with the cover 37 and the gate 26 is closed.
The molten metal 43 filled in the mold 11 is pressurized by air to combine the preform B and the molten metal 43. However, a high pressure casting method in which a high pressure is applied to the molten metal 43 by a pressure punch, a plunger or the like. Thus, the preform B and the molten metal 43 can be combined.

[0060]

As described above, according to the first aspect of the present invention, the composite is formed by pressing the molten metal filled in the mold, and has a core holding portion for holding the core member. The preformed body base was formed so as to have a gap between the preformed body and the core member, and the core holding portion was protruded from a part of the preformed body base.
In the invention according to claim 6, the core member base having the holding portion held by the composite preform is formed such that there is a gap between the core member and the preform. The holding portion was formed so as to protrude from a part of the core member base.
Therefore, according to these inventions, it is possible to prevent the core member from cracking due to thermal stress, to suppress the generation of burrs, and to improve the composite property of the molten metal and the preform.

According to the second aspect of the present invention, the base of the preform is formed in a ring shape, and the plurality of core holding portions are radially arranged at predetermined intervals in the circumferential direction on the inner periphery of the base of the preform. It protruded. In the invention of claim 7, the core member base is formed in a ring shape, and a plurality of holding portions are provided in the outer peripheral portion of the core member base so as to protrude in the radial direction at predetermined circumferential intervals. Therefore, according to these inventions, it is possible to obtain an optimal core member holding structure.

According to the third aspect of the present invention, the core holding portion has a higher porosity than the base of the preformed body. Also,
In the invention of claim 4, the core holding portion is made softer than the base of the preformed body. Therefore, according to these inventions, cracking of the core member due to thermal stress can be further suppressed.

According to the fifth aspect of the present invention, the core holding portion is
By configuring with a separate member from the preformed body base, while reducing the cost for forming the core holding part,
Cracking of the core member due to thermal stress can be prevented.

According to the eighth aspect of the present invention, since the core member is a salt core, the holding structure of the core member can be effectively used.

According to the ninth aspect of the present invention, as a method of manufacturing a composite metal part, a composite preform and a core member held by the preform are formed so as to have a gap with respect to a mating member. The formed base and a holding portion protruding from a part of at least one base of the preformed body and the core member, and the core member is held on the preformed body by the holding portion. The preform is supported in a mold in a state where the preform is filled, and molten metal is filled in the mold and pressurized to form a composite with the preform. The operation and effect of the invention can be obtained.

According to the tenth aspect of the present invention, the molten metal in the mold is pressurized by gas while the molten metal is filled into the mold from the gate of the mold, and the molten metal in the mold is closed. When compounding the preform and the molten metal while holding the core member, an optimal casting method can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a front view showing a main part of a piston for an automobile engine.

FIG. 4 is a cross-sectional view showing a manufacturing apparatus for manufacturing a piston.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a view showing a procedure from producing a composite preform to holding the salt core in the preform.

FIG. 7 is a view corresponding to FIG. 4, showing a state in which the preformed body holding the salt core has been inserted from the upper die insertion hole to each step portion of both side molds.

FIG. 8 is a view corresponding to FIG. 4, showing a state where a composite preform is supported in a product cavity.

FIG. 9 is a diagram corresponding to FIG. 4, showing a state where the molten metal is filled from the gate into the runner and the product cavity.

FIG. 10 is a view showing a state where the molten metal is completely filled in the mold;
FIG.

FIG. 11 is a view corresponding to FIG. 4, showing a state in which the gate is closed by a cover and the inside of the mold is substantially sealed.

FIG. 12 is a diagram corresponding to FIG. 4, showing a state in which the molten metal in the mold is pressurized with air.

FIG. 13 is a cross-sectional view showing a main part of a casting immediately after casting by a manufacturing apparatus.

FIG. 14 is a diagram corresponding to FIG. 1, showing the second embodiment.

15 is a sectional view taken along line XV-XV in FIG.

FIG. 16 is a diagram corresponding to FIG. 15 showing the third embodiment.

FIG. 17 is a perspective view showing a main part of a composite preform according to a fourth embodiment.

FIG. 18 is a top view showing a state in which the salt core according to the fifth embodiment is held by the composite preform.

[Explanation of symbols]

 B Preforming body for compounding C Salt core (core member) 1 Piston for automobile engine (composite metal part) 6 Composite part 8 Cooling oil passage 11 Mold 26 Gate 27 Runner 30 Preform base 31 Core holding Part 33 core holding member 37 cover 40 core member base 41 holding part 43 molten metal

Claims (10)

[Claims] 1. A composite preform having a core holding portion for holding a core member, wherein the preform is formed by pressing a molten metal filled in a mold and has a core holding portion. A preform having a base formed so as to have a gap, and wherein the core holding portion is provided so as to project from a part of the preform base. 2. The preform for compounding according to claim 1, wherein the base of the preform has a ring shape, and a plurality of core holding portions are circumferentially formed on an inner peripheral portion of the base of the preform. A preform for compounding characterized by being projected in the radial direction at a predetermined interval. 3. The preform for compounding according to claim 1, wherein the core holding portion has a higher porosity than a base of the preform. 4. The preform for compounding according to claim 1, wherein the core holding portion is softer than the base of the preform. 5. The composite preform according to claim 1, wherein the core holding portion is formed of a member different from the base of the preform. Preform for chemical conversion. 6. A core member having a holding portion that is held by a composite preform formed by pressurizing a molten metal filled in a mold, wherein the holding part is formed by: A core member having a core member base formed so as to have a gap therebetween, wherein the holding portion is provided so as to project from a part of the core member base. 7. The core member according to claim 6, wherein the core member base has a ring shape, and a plurality of holding portions are circumferentially spaced at predetermined intervals in an outer peripheral portion of the core member base. A core member protruding in the radial direction. 8. The salt core according to claim 6, wherein the salt is a core.
Or the core member of 7. 9. A composite preform formed by pressurizing a molten metal filled in a mold and a core member held by the composite preform, with respect to a mating member. A base formed to have a gap, and a holding portion protruding from a part of at least one base of the composite preform and the core member, and the composite is formed by the holding portion. The composite preform is supported by supporting the composite preform in a mold while holding the core member in the composite preform, and filling the mold with a molten metal and pressurizing the molten metal. A method of manufacturing a composite metal part, comprising: 10. The method for manufacturing a composite metal component according to claim 9, wherein the molten metal in the mold is pressurized by gas while the molten metal is filled into the mold from a mold gate and the mold is closed. Of manufacturing composite metal parts.