JPH09234545A - Holow core and mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin hollow core little in deformation at the time of pouring molten metal. SOLUTION: This hollow core 1 is formed by a cavity core part 2 forming a part of the wall surface of a product cavity 13 and an outer shell core part 3 connected to the cavity core part 2. A recessed part 7 is formed at a position 6 in the outer shell core part 3 opposed to the cavity core part 2, and the bottom part 8 of the recessed part 7 is connected to the cavity core part 2. The recessed part 7 is formed into a truncated cone state, and the bottom part 8 of the recessed part 7 is connected to the cavity core part 2, and the cavity core part 2 and the outer shell core part 3 are bridged with side wall parts 9 of the recessed part 7.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a casting core and a mold, and more particularly to a hollow core.

[0002]

2. Description of the Related Art As a hollow core housed in a space inside a mold, there is a hollow core shown in FIG.
Is composed of a cavity core portion 102 forming a part of the wall surface of the product cavity 101, and an outer shell core portion 103 connected to the cavity core portion 102.
02 and the outer core portion 103 form a hollow portion 104.

[0003]

When the cavity core portion 102 and the outer shell core portion 103 of the hollow core 100 are thinned, the molten metal 10 poured into the cavity core portion 102 is obtained.
The weight of 5 may cause deformation or cracks in the cavity core 102, which may cause casting defects in the obtained casting.
Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a hollow core in which deformation of the cavity core portion 102 is unlikely to occur even if the entire core is thinned.

[0004]

A hollow core according to claim 1 comprises a cavity core portion forming a part of a wall surface of a product cavity, and an outer shell core portion connected to the cavity core portion. A hollow core in which a hollow portion is formed from the cavity core portion and the outer shell core portion, a concave portion is formed at a portion of the outer shell core portion facing the cavity core portion, and the concave portion is formed. Is connected to the cavity core portion. A mold according to a second aspect comprises the hollow core according to the first aspect.

When a recess is formed in a portion of the outer shell core portion facing the cavity core portion and the bottom of the recess is connected to the cavity core portion, the outer shell core portion and the cavity core portion are separated from each other. Are bridged by the side wall of the recess, and the load bearing capacity of the cavity core is increased. Therefore, even if the thin hollow core is embedded in a sand mold and molten metal is poured into the cavity core, the cavity core is unlikely to be deformed or cracked.

[0006]

The shape of the recess is not particularly limited, and may be, for example, a truncated cone shape or a tubular shape. In addition, the recesses can be formed in various places as needed.

[0007]

EXAMPLES Examples of the present invention will be described below with reference to FIGS. The hollow core 1 is a shell core and is formed of a cavity core portion 2 and an outer shell core portion 3, and has a hollow portion 4 and an opening 5 on a side wall. A frustoconical recess 7 is formed in a portion 6 of the outer shell core 3 facing the cavity core 2, and a bottom 8 of the recess 7 is connected to the cavity core 2 to form a side wall 9 of the recess 7. Bridges the outer shell core portion 3 and the cavity core portion 2. The hollow core 1 may be molded as usual by using a mold having a truncated cone-shaped projection for forming the truncated cone-shaped recess 7 of the hollow core 1.

When casting using the hollow core 1, the hollow core 1 is embedded in a sand mold 10, and a product cavity of the sand mold 10 is passed through a sprue 11 and a runway 12 formed in the sand mold 10. Molten metal 14 is poured into 13. At this time, the side wall portion 9 of the concave portion 7 serves as a support pillar for supporting the cavity core portion 2, and the load capacity of the cavity core portion 2 becomes large. Is avoided.

The castings cast using the hollow core 1 had no casting defects due to deformation of the hollow core 1 and had good dimensional accuracy. FIG. 2 shows an embodiment of the present invention (indicated by a circle in the figure).
And a conventional example (shown by Δ in the figure) having the same structure as the embodiment of the present invention except that the recess 7 is not formed,
The deviation (indicated as "dimension deviation" in the figure) between the size of the target casting and the size of the actual casting when the wall thickness of the hollow core 1 is variously changed is shown. From FIG. 2, it is clear that the embodiment of the present invention has a smaller dimensional deviation and a higher dimensional accuracy than the conventional example, and in particular, the difference becomes larger as the hollow core has a smaller wall thickness.

[0010]

According to the present invention, a concave portion is formed in a portion of the outer shell core portion facing the cavity core portion, and the bottom portion of the concave portion is connected to the cavity core portion, whereby the hollow core The withstand load of the cavity core portion can be increased, and therefore, the deformation of the cavity core portion at the time of pouring the molten metal can be avoided, and a casting with high dimensional accuracy can be obtained. Further, since the hollow core can be thinned, the amount of core sand used is reduced, the molding time is shortened, and the manufacturing cost of the hollow core is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold in which a hollow core according to an embodiment of the present invention is embedded.

FIG. 2 is a graph comparing the dimensional accuracy of a casting cast using the hollow core of the above example with the dimensional accuracy of a casting cast using a conventional hollow core.

FIG. 3 is a sectional view of a mold in which a hollow core of a conventional example is embedded.

[Explanation of symbols]

 1 Hollow Core 2 Cavity Core 3 Outer Shell Core 7 Recess 8 Bottom 10 Sand Mold

Claims (2)

[Claims] 1. A cavity core portion forming a part of a wall surface of a product cavity, and an outer shell core portion connected to the cavity core portion. The cavity core portion and the outer shell core portion. In the hollow core in which the hollow portion is formed, a concave portion is formed at a portion of the outer shell core portion facing the cavity core portion, and a bottom portion of the concave portion is connected to the cavity core portion. Hollow core. 2. A mold comprising the hollow core according to claim 1.