JP3198706B2 - Manufacturing method of piston with cooling cavity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a piston with a cooling cavity, and is used as a method for manufacturing a piston for an automobile engine.

[0002]

2. Description of the Related Art As a conventional technique for manufacturing a piston with a cooling cavity, for example, there is one disclosed in Japanese Patent Application Laid-Open No. Sho 60-15041.

In this prior art, after a ceramic core is arranged on a core mold, an outer mold is arranged around the core, and the outer mold is formed between the periphery of the core mold and the ceramic core and the inside of the outer mold. In this method, a metal solution (for example, an aluminum solution) is injected into a space.

[0004] When the solution solidifies and the core and outer molds are removed, the piston is cast with the ceramic core remaining inside. Then, when the piston is forcibly vibrated, the ceramic core collapses and is removed. The piston 1 having a cavity therein can be cast. This is shown in FIG. 4, 2 is a cavity, and 3 is a cooling oil injection port.

[0005] However, with such a ceramic core removing means, there is a possibility that the core remains and it is difficult to confirm the core.

FIG. 5 shows a heavy-duty piston type structure using a soluble core formed of a salt or the like having excellent removability.

Here, reference numeral 4 denotes a salt core having a foot 4a,
a is an upper mold 5b is a main mold, 6 is a five-piece core mold composed of a center core, a Philip core, and a side core, 7 is a wrist pin, and 8 is a metal solution.

After casting with the piston type structure, the upper die 5
a, after removing the main mold 5b and the core mold 6, by spraying water or the like into a space corresponding to the foot of the salt core 4, the salt core 4 remaining inside the piston is removed and the cavity 2 is removed. Is formed.

[0009]

As described above, since the soluble core is generally formed of a small specific gravity material such as a salt, the specific gravity of the soluble core is smaller than the specific gravity of the metal solution. The soluble core may rise from the core type.

Accordingly, the present invention has as its technical object to prevent the soluble core from rising from the core type when the metal solution is injected using a soluble core such as a salt core. Is what you do.

[0011]

The technical means taken in the present invention to solve the above technical problem is to dispose a soluble core on a core type and to dispose a soluble core around the core type and the soluble core. In a method for manufacturing a piston with a cooling cavity, in which a metal solution is injected, a core mold is extracted after solidification of the metal solution, and a soluble core is dissolved and removed, a core is extended so as to extend toward the soluble core. Fix the cast pin in the mold, form a hole in the soluble core, fit the tip of the cast pin in the hole, and make a hole in the tip of the cast pin so as to open toward the soluble core. That is, a ball and a spring for biasing the ball in a direction of pressing the ball against the soluble core are provided in the hole.

[0012]

According to the above technical means, a hole is formed at the tip of the core pin fixed to the core mold, and a ball and a spring for biasing the ball against the soluble core are provided in the hole. Therefore, when the cast pin is inserted into the hole of the soluble core, the ball is pressed against the soluble core by the spring, and the soluble core is fastened to the cast pin. As a result, it is possible to prevent the soluble core from rising from the core type when the metal solution is injected.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 shows a piston 1 with a cooling cavity according to this embodiment.
FIG. 4 is an explanatory view showing a state in which a salt core (soluble core) 12 is set in a split core mold 11 in order to cast a core. FIG.
FIG. 3 is an explanatory view of a state where the salt core 12 is fastened to the cast pin 13.

As shown in FIGS. 1 and 2, the salt core 1
2 is arranged on the core mold 11. In the salt core 12, a hole 12a opening toward the core mold 11 is formed.
3a is fitted. The cast pin 13 is fixed to the center core 11 a of the core mold 11, and extends toward the salt core 12. Here, when the center core 11a is moved downward in the figure to remove the cast pin 13 from the salt core 12, the cooling oil passage 3 of the piston 1 as shown in FIG. 4 is formed.

FIG. 3 is an explanatory view showing the structure of the tip 13a of the cast pin 13. As shown in FIG.

As shown in FIG. 1, a hole 16 opening rightward in the figure is formed at the tip 13a of the cast pin 13, in which a ball 14 and a spring 15 are arranged. Has been established. The spring 15 urges the ball 14 rightward in the figure to press the ball 14 against the salt core 12.

The operation of the above configuration and a method of manufacturing the piston 1 with a cooling cavity according to this embodiment will be described.

The tip 13a of the cast pin 13 fixed to the center core 11a of the core mold 11 is inserted into the hole 12 of the salt core 12.
a. Ball 14 in hole 16 at tip 13a
Is pressed in the right direction in the figure by a spring 15 to fasten the salt core 12 to the cast pin 13. In this state, when the metal solution was injected around the core mold 11 and the salt core 12, the salt core 12 did not float from the core mold 11.

After the metal solution solidified, the core pin 11 was moved downward in the drawing to remove the cast pin 13 from the salt core 12. Next, water and the like were sprayed toward the hole 12a to dissolve and remove the salt core 12, thereby producing the piston 1 with a cooling cavity shown in FIG. The cooling cavity 2 is provided with a salt core 12
Are formed as a result of the removal of the cast oil, and the cooling oil passage 3 is formed as a result of the removal of the cast pin 13.

As described above, in this embodiment,
A hole 16 is formed in the tip portion 13a of the cast pin 13 fixed to the center core 11a of the core mold 11, and the ball 14 and a spring 15 for urging the ball 14 in the direction of pressing the ball 14 against the salt core 12 are provided in the hole 16. When the tip is inserted into the hole 12a of the salt core 12, the ball 14 is pressed against the salt core 12 by the spring 15, and the salt core 12 is Will be concluded. As a result, the salt core 12 is prevented from rising from the core mold 11 when the metal solution is injected.

[0022]

The present invention has the following effects.

(1) In any of the embodiments of the present invention, the salt core can be easily fixed.

(2) As means for fixing the salt core, there are also adsorption means utilizing magnetic force, but these are inferior in workability because the adsorption target is assembled to the soluble core. In contrast, the method according to the present embodiment is extremely easy to assemble.

(3) In the case where the conventional suction means is provided, an operation of removing the suctioned means is required, but the method of the present embodiment does not need to do so at all.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which a cored pin is fixed to a core mold and a salt core is fixed to a tip of the cored pin.

FIG. 2 is an explanatory view of a state in which a salt core is fixed to a cast pin.

FIG. 3 is an enlarged cross-sectional view of a tip end of a cast pin.

FIG. 4 is a sectional view of a piston with a cooling cavity.

FIG. 5 is a schematic explanatory view of a mold structure when casting a piston with a cooling cavity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piston with cooling cavity 2 Cooling cavity 11 Core 12 Salt core (soluble core) 12a hole 13 Cast pin 13a Tip of cast pin 14 Ball 15 Spring 16 hole

Continuation of the front page (56) References JP-A-4-237539 (JP, A) JP-A-4-237538 (JP, A) JP-A-60-15041 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) B22C 9/10 B22C 9/24 F02F 3/00

Claims (1)

(57) [Claims] A core is placed on a core mold, a metal solution is injected around the core and the soluble core, and after the metal solution solidifies, the core is pulled out. In a method of manufacturing a piston with a cooling cavity by dissolving and removing a soluble core, a cast pin is fixed to the core mold so as to extend toward the soluble core, and a hole is formed in the soluble core. Forming a hole in the tip of the die-casting pin so as to open toward the soluble core, and fitting the ball and the ball in the hole. A spring for urging the piston in a direction in which the piston is pressed against the soluble core is provided.