JPH0357327Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a stalk used in a low pressure casting method.

(Prior Art) The low-pressure casting method is a casting method in which the molten metal surface in a molten metal holding furnace is pressurized and the molten metal is poured into a metal cavity. The molten metal is poured through a single pipe called a stalk.

In such a casting method, the pressure inside the holding furnace is reduced every time one casting operation is completed, and the molten metal in the stalk is temporarily returned to the molten metal holding furnace. This process is hot water drainage. Then, in the next new casting operation, the inside of the holding furnace is pressurized again, and the molten metal inside the holding furnace is injected into the cavity of the mold via the stalk.

(Problems to be solved by the invention) A conventional stalk is a single pipe, and both pouring and discharging of the metal are carried out through that pipe. Therefore, a portion of the molten metal returned to the holding furnace in the discharging process of the previous casting operation is introduced into the cavity of the mold again in the pouring process of the subsequent casting operation. However, since the molten metal returned to the holding furnace in this discharge process is contaminated with impurities such as slag, if a large amount of these impurities are introduced into the cavity, the cast product may be defective. This will cause this to occur.

(Means for solving the problem) A main pipe extending from the mold of the present invention into the molten metal, a bypass pipe branching from the middle of this main pipe and also extending into the molten metal, and a bypass pipe extending from the lower part of the main pipe into the molten metal. It consists of a check valve disposed below the branch point with the bypass pipe in the main pipe to prevent molten metal from being sucked into the cavity.

(Function) According to the above configuration, in the pouring process, the check valve prevents the molten metal from being sucked into the cavity from the lower part of the main pipe, so the molten metal is sucked only from the bypass pipe, and the molten metal is sucked into the main cavity. It is introduced into the cavity through the upper part. On the other hand, in the discharging process, the molten metal in the upper part of the main pipe containing a large amount of slag is not returned to the lower part of the bypass pipe but is returned to the lower part of the main pipe. Therefore, the molten metal containing a large amount of slag discharged in the previous casting operation is not introduced into the cavity in the pouring step of the next casting operation, thereby preventing product defects.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In FIG. 1, which shows a casting apparatus in cross section, a main pipe 1 consists of an upper small diameter part 1a and a lower large diameter part 1b, and an annular shoulder 2 is formed at the connecting part. The upper end of the small diameter portion 1a is the mold D.
The lower end of the large diameter portion 1b is immersed in the molten metal of the holding furnace C.

A conical float valve 3 that can be raised and lowered as the molten metal surface rises and lowers is disposed within the large diameter portion 1b of the main pipe 1. When the float valve 3 is pushed up as the molten metal level rises, its conical surface 4 engages with the shoulder 2, closing off the space between the large diameter section 1a and the small diameter section 1b of the main pipe 1. In addition, in this example, the float valve 3 is formed in a conical shape, but it may have a shape such as a sphere.

Further, an inverted L-shaped bypass pipe 5 is connected to the lower part of the small diameter portion 1a of the main pipe 1 in a bifurcated manner. This bypass pipe 5 communicates with the main pipe 1, and its lower end is immersed in the molten metal.

Next, the action of the stalk in casting will be explained mainly with reference to FIGS. When the inside of the holding furnace C is pressurized in the pouring process, the molten metal rises inside the large diameter portion 1b of the main pipe 1 and the inside of the bypass pipe 5 at the same time. At this time, within the large diameter portion 1b of the main pipe 1, the float valve 3 also rises together with the molten metal. and,
When the molten metal level rises further, the conical surface 4 of the float valve 3
is closely engaged with the shoulder 2, and the large diameter portion 1 of the main pipe 1
b and the small diameter portion 1a are closed (Fig. 2),
Introduction of molten metal from the large diameter portion 1b side into the small diameter portion 1a is prevented.

Therefore, the molten metal is introduced into the cavity V of the mold D only from the bypass pipe 5 side, through the small diameter portion 1a of the main pipe 1. (Figure 2).

On the other hand, in the discharging step, when the pressure inside the holding furnace C is reduced, the molten metal containing a lot of slag and filling the small diameter portion 1a of the main pipe 1 begins to descend. At the same time, the float valve 3 descends to open the space between the small diameter section 1a and the large diameter section 1b of the main pipe 1, so the molten metal in the small diameter section 1a is not returned to the bypass pipe 5 side, and the large diameter section 1
descend into b (Fig. 2). As a result, most of the slag generated within the small diameter section 1a of the main pipe 1 will be descended to the large diameter section 1b side of the main pipe 1 (second
figure). In addition, since the float valve 3 has a conical shape,
In this draining process, slag does not accumulate on the valve and the valve function is not impaired.

As mentioned above, the cavity V in the pouring process
The molten metal introduced into the inside is always the molten metal on the bypass pipe 5 side, and in the discharging process, the molten metal containing slag is not returned to the bypass pipe 5 side, so even if the casting operation is performed continuously. The slag in the molten metal returned to the holding furnace C in the discharging process of the previous operation will not be introduced into the cavity V of the mold D in the pouring process of the next operation.

(Effect of the invention) The stalk of this invention consists of a main pipe extending from the mold into the molten metal, a bypass pipe branched from the middle of this main pipe and also extending into the molten metal, and a bypass pipe extending from the bottom of the main pipe into the cavity of the mold. In order to prevent the inhalation of molten metal, the molten metal pouring process and the discharging process are performed through separate pipes. It is done. Therefore, impurities such as slag discharged into the molten metal during the discharging process of the previous casting operation will not be introduced into the cavity during the pouring process of the next casting operation, resulting in product defects caused by these impurities. occurrence is prevented.

[Brief explanation of drawings]

The drawings show an embodiment of this invention; Fig. 1 is a sectional view of a casting device with a stalk attached; Figs. 2-
FIG. 2 is an explanatory diagram showing the flow of molten metal in the pouring and discharging process. 1... Main pipe, 3... Float valve, 5... Bypass pipe.

Claims (1)

[Scope of utility model registration request] There is a main pipe that extends from the mold into the molten metal, a bypass pipe that branches off from the middle of this main pipe and also extends into the molten metal, and a main pipe that prevents the molten metal from being sucked into the mold cavity from the lower part of the main pipe. A low-pressure casting stalk characterized by comprising a check valve disposed below a branch point with a bypass pipe in the pipe.