JP2890735B2 - Casting mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold, and more particularly to an improvement of a runner in a mold.

[Conventional technology]

Generally, a mold applied in casting has a cavity formed therein in a shape corresponding to a product, and a runner for communicating the cavity with the outside of the mold. The molten metal is injected into the cavity through the gate.

[Problems to be solved by the invention]

By the way, in the conventional mold, since the runner is formed in a straight line, the flow velocity of the molten metal in the runner becomes large, and a turbulent state occurs.

When pouring into the cavity in such a state,
Impurities, particularly oxides, contained in the molten metal enter the cavities as they are, which may cause poor appearance such as underfill on the product surface.

For this reason, conventionally, a ceramic strainer is disposed in the runner, and the strainer is used to prevent impurities from entering the cavity.

However, in the conventional configuration in which the strainer is provided in the runner, the number of manufacturing steps and the number of parts increase, which leads to an increase in product cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mold capable of inexpensively preventing poor product appearance caused by intrusion of impurities contained in a molten metal in view of the above circumstances.

[Means for solving the problem]

According to the present invention, a first pool portion and a second pool portion which are sequentially arranged on a runner from a gate to a cavity and have a large cross-sectional area, and one side end of the first pool portion Is provided between the first pool and the one end of the second pool to suppress the flow rate of the molten metal passing through the first pool and included in the molten metal at the first pool. A first throttle portion for retaining impurities to be accumulated and a second pool portion provided between the other end of the second pool portion and the cavity to suppress the flow rate of the molten metal passing through the second pool portion. And a second throttle portion for stagnating impurities contained in the molten metal in the second pool portion.

[Action]

According to the above configuration, the flow rate and flow rate of the molten metal poured from the gate are suppressed by the narrowing action of the first narrowing section and the second narrowing section. Since each of the second pools stagnates, it is possible to prevent the impurities from entering the cavity.

Moreover, since the first and second pools and the first and second throttles are connected to each other in a bent state, the time required for the molten metal to pass through the first and second pools is reduced. become longer. Therefore, impurities contained in the molten metal are reliably stagnated in the first and second pools.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings showing examples.

FIG. 1 conceptually shows a cross section of a mold according to the present invention. Although not explicitly shown in the figure, the mold 1 exemplified here is a so-called vertical split type configured by combining a plurality of sand molds, and has a cavity therein.
Has 2,2.

The cavities 2, 2 each have a shape corresponding to a product to be molded, and are arranged side by side within the mold 1 with an interval therebetween.

The mold 1 has a runner 10 at a position located between the cavities 2 and 2. The runner 10 extends in the vertical direction of the mold 1 (vertical direction in the figure), and a sprue cup 11, a vertical road portion 12, a crank portion 13, and a branch portion 14 are respectively formed from the upper part thereof. .

The spout cup 11 has a conical shape whose diameter decreases as it goes downward, and the spout 11 is placed on the upper surface 1 a of the mold 1.
have a.

The vertical path portion 12 has a constant circular or rectangular bar shape in cross section, and extends downward from the bottom surface of the sprue cup 12.

As shown in FIG. 2, the crank portion 13 is
A horizontally extending first
The first pool 15 has a thin plate shape having the same width as that of the first pool 15, and the first pool 15 extends downward from one end of the first pool 15. Throttle passage (throttle section)
16, extending horizontally from the first throttle passage 16,
The second pool having substantially the same volume as the first pool 15
And a second throttle passage (throttle portion) 18 having a thin plate shape and extending downward from the other end of the second pool portion 17. Second throttle passage
It is connected to the branch part 14 via 18.

The branch portion 14 has a cross section that is sufficiently larger than the second throttle passage 18 in the crank portion 13 and has a communication passage 19,1.
It is connected to the lower part of the cavities 2, 2 via 9.

FIG. 3 shows a model 20 applied when the crank portion 13 and the branch portion 15 are formed. This model 20 has a right surface 20R and a left surface 20L which are joined to each other by a bonding surface 21.
The portions corresponding to the runner 10 are given the same numbers.

In the mold 1 having the above-described configuration, when the molten metal is poured into the gate cup 11 through the gate 11a, the molten metal is formed in a vertical path.
12, the crank part 13, the branch part 14, and the communication passages 19, 19 are injected into the cavities 2, 2, respectively.

During this time, the flow rate and flow rate of the molten metal that has reached the first pool portion 15 from the sprue cup 11 via the vertical path portion 12 is suppressed by the first throttle passage 16, and further passes through the first throttle passage 16. When it is laminar flow.

At this time, impurities such as oxides contained in the molten metal have a lower specific gravity than that of the molten metal.
And stays in the first pool 15 as it is. That is, impurities are removed from the molten metal while passing through the first pool 15 and the first throttle passage 16.

Further, the molten metal that has passed through the first throttle passage 16 and reached the second pool 17 is laminarized again by the second throttle passage 18, and when the molten metal passes through the second throttle passage 18. Is removed.

As described above, in the mold 1, since impurities contained in the molten metal are sequentially removed in the runner 10, external appearance such as underfilling of the product surface due to invasion of these impurities into the cavities 2 and 2. Defects can be prevented as much as possible.

In addition, since the first and second pools 15 and 17 and the first and second throttles 16 and 18 are connected to each other in a bent crank shape, the molten metal is formed by these first and second pools.
The time required to pass through the water pools 15 and 17 becomes longer. Therefore, impurities such as oxides contained in the molten metal are reliably stagnated by the first and second pools 15 and 17, and the surface of the product caused by the intrusion of the impurities into the cavities 2 and 2 is prevented. The appearance defect can be more reliably prevented.

In the above-described embodiment, a vertically split mold is illustrated, but the present invention is not limited to this. Although the mold 1 has two cavities 2, 2, the number of cavities does not necessarily have to be two.

Further, in the above embodiment, two hot water pools
Although the squeezers 15 and 17 and the two throttles 16 and 18 are arranged, the number of pools and throttles may be three or more. Furthermore, although the above-mentioned pool portions 15, 17 and the throttle portions 16, 18 are connected in a crank shape, the present invention is not limited to this. Further, although the thin plate-like passages 16 and 18 are illustrated as the throttle portions, other passages may be used as long as the flow rate and the flow velocity of the molten metal are suppressed.

〔The invention's effect〕

As described above, according to the mold according to the present invention, the simple configuration of providing the runner with the first and second throttles and the first and second throttles allows the cavity of the impurity contained in the molten metal to enter the cavity. Since the intrusion is prevented, it is possible to prevent inferior appearance of the product at low cost.

Moreover, since the first and second pools and the first and second throttles are connected to each other in a bent state, the time required for the molten metal to pass through the first and second pools is reduced. As a result, the effect of removing impurities contained in the molten metal becomes significant.

[Brief description of the drawings]

FIG. 1 is a sectional view conceptually showing a mold according to the present invention,
FIG. 2 is a perspective view of a principal part schematically showing the shape of a mold runner according to the present invention, and FIG. 3 is a conceptual view of a model applied when building a mold runner according to the present invention. FIG. 2 ... cavity, 10 ... runner, 11a ... gate, 15,17 ... pool, 16,18 ... throttle.

Claims (1)

(57) [Claims] 1. A first pool and a second pool which are sequentially arranged in a runner from a gate to a cavity and have a large cross-sectional area, and one side end of the first pool. Provided between the first pool portion and one end of the second pool portion to suppress a flow rate of the molten metal passing through the first pool portion, and to prevent the flow of the molten metal in the first pool portion during the molten pool. A first constricted portion for stagnating contained impurities; and a second constricted portion provided between the other end of the second pool portion and the cavity to suppress a flow rate of molten metal passing through the second pool portion. And a second squeezing portion for stagnating impurities contained in the molten metal in the second pool portion.