JPH10118760A - Manufacture of hollow casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the concentration of stresses by joining metallic plates, manufacturing a hollow body having similarily smaller than a casting shape, using a hollow metallic core communicating gas venting small diameter pipes, casting, cutting off and removing the small diameter pipes and closing with a plug. SOLUTION: The metallic plates 1, 2 are joined with a press or a welding and the hollow metallic core 6 having almost similarily smaller outer shape than the shape of a metallic casting frame W and the hollow part 3 is manufactured. The metallic plate 2 is formed as rugged surface so as to absorb the thermal expansion at the time of casting and the shrinkage at the time of solidifying. The small diameter pipes 4 for gas venting are communicated and fixed to the outside of the hollow metallic core 6. The hollow metallic core 6 is set in a sand mold 7 and the casting executed by pouring molten metal. After completing the casting, the small diameter pipes 4 for gas venting are cut off along the end surfaces of the whole casting frame W and screw holes are worked to the remained small diameter pipe 4 parts and bolts are buried to close the holes by plug-welding. By this method, the communicating parts become the small diameters and the concentration of stresses can be prevented.

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 hollow casting whose weight is reduced for ease of handling and reduction of manufacturing cost.

[0002]

2. Description of the Related Art Most of the metal molds used for casting in conventional castings are made of castings. As the size of the metal molds increases, the wall thickness increases and the weight increases. However, there has been a problem that the equipment for handling the gantry must be strengthened accordingly. In order to solve this problem, it has been attempted to use a sand core to cast a gold flask in which the inside of the side wall is hollow when casting a gold flask. However, in casting using a sand core, it is necessary to extract the core sand after casting from the baseboard part, so the baseboard part is considerably enlarged, and after the core sand is extracted, it remains as a large through hole, and this communication The stress is concentrated on the hole, and the problem of deteriorating the durability of the cast iron frame has newly occurred.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a method of manufacturing a hollow casting without connecting large through holes in which stress is concentrated in a hollow portion. The purpose is to:

[0004]

In order to achieve the above object, a method of manufacturing a hollow casting according to the present invention comprises a method of pressing a plurality of metal plates by press bonding or welding bonding so that the outer shape is substantially similar to a casting shape to be manufactured. A hollow metal body having a small hollow structure having a hollow inside, and a small-diameter pipe for degassing provided at an appropriate distance from the outside of the hollow structure so as to communicate with the hollow part. The core is set in a sand mold in which the shape of the casting to be manufactured is molded, a casting is cast, a small-diameter pipe in the cast casting is cut along an end face of the casting, and the small-diameter pipe is cut. It is characterized by closing the mouth.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to the drawings by taking as an example the case of manufacturing a hollow cast iron frame. First, as shown in FIG. 1, a plurality of preformed metal plates 1 and 2 are press-joined (or may be weld-joined) so that the outer shape is substantially similar to the shape of a metal mold frame W to be manufactured, and the inside thereof is formed. A hollow structure having the hollow portion 3 is manufactured. In this case, the metal plate 2 corresponding to the long linear surface of the gold casting frame W is formed with an uneven surface so that the thermal expansion 2A during casting and the contraction 2B during solidification can be absorbed by deformation. Next, a small-diameter pipe 4 for venting gas is fixed to the outside of the manufactured hollow structure at an appropriate interval so as to communicate with the hollow portion 3. If necessary, the lower part of the hollow structure (FIG. 1)
, A hollow metal core 6 is obtained by appropriately attaching a keel 5 to the lower portion of the metal plate 1).

Next, as shown in FIG. 2, the hollow metal core 6 obtained as described above is set in the manner of a core set in a sand mold 7 in which the shape of a metal mold frame W to be manufactured is formed. The molten metal is poured into the casting and casting is performed to obtain a semifinished gold cast frame as shown in FIGS. In this casting, as shown in FIG. 1, the metal plate 2 undergoes thermal expansion 2A during casting and contracts 2B with solidification. However, since the metal plate 2 has an uneven surface, the metal plate 2 is deformed. This will be absorbed. Although the air in the hollow portion 3 is also thermally expanded, the gas is vented from the small diameter pipe 4 so that the hollow metal core 6 does not break. Next, as shown in FIG. 4, a small-diameter pipe 4 for gas release protruding from the main body of the obtained gold frame is cut along the end face of the gold frame W and a tap is added to the small-diameter pipe 4 remaining. Then, a screw hole 8 is formed, and all screw bolts 9 are embedded in the screw hole 8 and plug welding 10 is performed to completely seal the hollow portion 3 of the gold casting frame W. As described above, a hollow cast iron frame is manufactured, and the present invention can be applied to the manufacture of a casting that requires a reduction in weight while maintaining durability, in addition to the gold cast frame.

[0007]

As is apparent from the above description, the present invention provides a hollow casting in which a plurality of metal plates are joined to form a casting which is to be manufactured by joining a plurality of metal plates. A hollow metal core is formed by connecting a small-diameter pipe for venting gas to the hollow portion of the hollow metal core, and a casting is cast using the hollow metal core. Since the pipe is cut and the cut end is closed, the hole communicating with the hollow portion of the casting becomes extremely thin, and a hollow casting in which the problem of stress concentration as in the case of a large through hole is eliminated is manufactured. Will be able to do it.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing an arrangement relationship between a metal mold frame and a hollow metal core.

FIG. 2 is a cross-sectional view showing a casting state of a gold flask.

FIG. 3 is a side view of a cast gold flask.

FIG. 4 is an enlarged cross-sectional view showing a closed state of a small-diameter pipe for degassing.

[Explanation of symbols]

 1 2 Metal plate 3 Hollow part 4 Small diameter pipe 6 Hollow metal core 7 Sand mold 9 Full screw bolt 10 Plug welding

Claims (1)

[Claims] A hollow structure is formed by press-welding or welding-joining a plurality of metal plates (1) and (2) to form a hollow structure substantially similar to a casting shape to be manufactured and having a hollow portion (3) inside. A hollow metal core 6 provided with a small-diameter pipe 4 for degassing at an appropriate interval on the outer side of the structure and communicating with the hollow portion 3 is formed into a sand mold 7 having a molding shape to be manufactured. The casting W is cast by setting the core, the small-diameter pipe 4 part of the cast W is cut along the end face of the casting W, and the cut end of the subtotal pipe 4 is closed 10. Method of manufacturing hollow casting