JP2751291B2 - Mold structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Industrial Field of the Invention The present invention relates to a dam structure of a mold in precision casting.

b. Conventional technology Many precision casting products by the lost wax method are used for automobile mission parts, motorcycle body parts, outboard motor hump case parts, and other parts constituting aircraft, medical equipment, and the like.

FIG. 5 to FIG. 7 illustrate an example of a conventional product produced by the lost wax method and a mold structure near a sprue and a weir portion. The product d is filled into the portion of the product d via the portion c, and a cast product in which the gate a, the runner b, the weir c, and the product d are solidified as shown in the figure is obtained. After demolding, the product d is cut from the weir c by a mechanical cutting method using a saw blade, a grindstone, or the like, or the product d is separated from the notch-shaped portion of the weir c by applying vibration stress. Has been taken.
The cross section of the weir portion is circular, square (rectangular, rectangular, etc.).

As shown in FIG. 5, the method of applying vibration to separate the product d is to mix the gate a and the runner b with a plurality of products d branched therefrom.
The casting which has been removed from the mold is integrally supported by the support means f as shown in FIG. 5, and the moment generated by the weight of the product d by vibrating the casting from the vertical direction (see the arrow). Is added to the notch-shaped cross section e of the weir portion c, and it is broken and separated therefrom (vibration cutting method).

On the other hand, when casting the molten metal into the mold, a separate ceramic filter is used at the boundary between the gate and the runner to prevent the inclusion of unnecessary inclusions and slag mixed in the molten metal. There are many examples.

c. Problems to be Solved by the Invention In the above vibration cutting method, when the area of the notch-shaped cross section e of the weir is reduced, it is easy to break, the product can be easily separated, and the slag and inclusions are more easily wound. Although it can be prevented effectively, there is a problem that the model is easily damaged during the process of manufacturing and handling the mold.

Also, when the cross-sectional area of the weir is small, this portion tends to solidify first at the time of casting, so that the supply of the molten metal to the product portion is not sufficient, so that there is a problem that shrinkage cavities easily occur in the product.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mold dam structure which solves the above problems.

d. Means for Solving the Problems In accordance with the above object, the present invention relates to a mold having a structure in which a molten metal is cast from a gate through a runner to a product part, and a weir is provided between the product part and the runner. The above problem was solved by providing a mold structure having a plurality of divided notched weirs provided with slits provided in the weir portion along the flow direction of the molten metal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 and FIG. 2 show an integrated casting before the product is separated as shown in FIG. 5 and FIG.
1 is a cast product, and 3 is a weir provided between the product 1 and a runner. The weir 3 is provided at a boundary with the product 1 in a state where the weir 3 is branched into a plurality of parts through a slit 6 at an intermediate portion thereof.
Notches 3a and 3b are formed, and notches (cuts) 4a and 4b are provided around these weirs 3a and 3b, respectively.

The slits 6 are arranged along the direction of flow of the molten metal, and there are some differences depending on the size of the product, the material and the temperature of the molten metal, the casting time, and other various conditions. 3 mm or less. If it is 3 mm or more, the effect of the heat retention hot spot aimed at by the present invention (described later) cannot be obtained.

The cross sections of the weirs 3a and 3b are circular, square, and other suitable cross-sectional shapes.

Incidentally, the above embodiments are expediently products after casting,
Although the mold structure has been described by the weir portion, the lost wax method has a substantially similar shape to the wax model, so that the mold structure can be described thereby.

FIGS. 3 and 4 show another embodiment in which the weir portion is divided into three, three weirs are provided, and slits are provided between the weirs.

e. Operation Now, when the molten metal is cast into the mold having the above structure, the molten metal passes through the weirs 3a and 3b branched from the runner formed in the mold via the weir portion 3, respectively, and is filled into the part to be the product 1. .

The cross-sectional area of each of the weirs 3a and 3b is narrower than the conventional cross-sectional area of the weir due to the slit 6, and the inflow of the slag and inclusions to the product 1 side by the notches 4a and 4b is effective. Is blocked. That is, even if the cross-sectional area of the sum of the weirs 3a and 3b is the same as the cross-sectional area of the conventional weir portion, the amount of molten metal that the weirs 3a and 3b touch each of the notches increases, and Slag and inclusions are reduced.

The provision of the slit 6 reduces the individual cross-sectional area of each of the weirs 3a and 3b, and therefore, there is a concern that the molten metal in that portion is rapidly cooled and shrinkage cavities are generated in the product 1. Slit 6 made of material
If the portion is smaller than the predetermined width, that portion is wrapped in the cast metal and becomes a heat retaining hot spot, thereby preventing early solidification of the molten metal touching the portion. Therefore, replenishment of the molten metal from the runner to the product 1 through the weir portion is performed with almost no problem. That is, a small casting area does not become a disadvantage, and a sound casting product without shrinkage cavities can be obtained.

Further, since the slit 6 is interposed between the weirs 3, there is almost no difference in strength from the conventional one.

f. Effects of the Invention As described above, according to the mold weir structure of the present invention,
In pouring the molten metal into the mold without weakening the strength of the weir, it is possible to effectively prevent slag and inclusions mixed in the molten metal from being mixed into the product. Therefore, the product does not suffer from defects such as shrinkage cavities, and the use of a conventionally used ceramic filter can be omitted.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a weir portion of a mold structure according to the present invention, FIG. 2 is an explanatory sectional view taken along line AA of FIG. 1, and FIGS. 3 and 4 are other embodiments of the present invention. FIG. 5 is an explanatory view corresponding to FIG. 2, FIG. 5 is an explanatory view showing a state before a cast product having a conventional structure is separated, FIG. 6 is a plan view showing a cut of the gate of FIG. 5,
FIG. 7 is an enlarged explanatory view taken along the line BB of FIG. 1. Cast products, 3 ... Weirs, 3a, 3b ... Divided weirs, 6 ... Slits.

Claims (1)

(57) [Claims] 1. A mold having a structure in which a molten metal is cast from a gate to a part to be a product via a runner, and a weir is provided between the part to be a product and the runner, and a flow direction of the molten metal in the weir. Characterized in that a plurality of divided notched weirs are provided with slits interposed therebetween.