JPH0534848Y2 - - Google Patents

Description

[Detailed description of the invention] <<Field of industrial application>> The present invention relates to a sprue structure for a low-pressure casting device, and more specifically, the molten metal is raised from a stalk by applying pressure to the molten metal, and This invention relates to a sprue structure for a low-pressure casting device that forms a casting by filling a mold through the gate.

<<Prior Art>> In a low-pressure casting apparatus, it is desirable that the molten metal be in a molten state on the stalk side and rapidly solidified on the mold side. However, the stalk side is in contact with the atmosphere and has a small heat capacity, so it is easy to dissipate the heat held by the molten metal, and there is a risk that the solidification of the molten metal progressing in the mold will also reach the stalk side. There are problems such as clogging and casting remaining in the sprue. For this reason, conventionally, the stalk was heated using a heating means such as a burner, but with this method, the temperature of the mold increases through the sprue, leading to deterioration of the strength and toughness of the casting near the sprue. This causes an inconvenience.

Therefore, as shown in Japanese Utility Model Application Publication No. 53-76126, a sprue bush was installed between the stalk and the lower die.
The solidification state of the molten metal can be controlled by constructing the sprue bushing with a heat insulating material, or by providing a heating coil in the lower part of the sprue bushing and a cooling water hole in the upper part, as shown in Japanese Utility Model Application No. 53-81621. A control configuration is known.

《Problem to be solved by the invention》 However, in the case where the sprue is made of a heat insulating material as in the former case, the heat insulating material has many pores to contain a large amount of air. There is a risk of the molten metal penetrating to the outside through the
Furthermore, the latter arrangement in which the heating coil and cooling water holes are provided in the sprue bush is complicated, and heating and cooling during operation are complicated, resulting in high costs.

This idea was made in view of the problems mentioned above.
The purpose of this is to control the solidification state of the molten metal at the sprue connecting part between the stalk of the low-pressure casting device and the mold sprue, and to prevent the molten metal from penetrating into this part.
Moreover, it is an object of the present invention to provide a sprue structure for a low-pressure casting device that has a simple configuration.

<Means for Solving the Problems> In order to achieve the above object, the present invention uses low-pressure casting in which pressure is applied to the molten metal to raise the molten metal from a stalk, and the molten metal is filled into a mold through a sprue to form a casting. In the sprue structure of the device, the sprue connection part between the stalk and the sprue is configured as a laminate of a plurality of heat insulators made of ceramic wool and a seal ring interposed between the heat insulators, and the laminate is pressurized. As a result, the seal ring is embedded and integrally attached to the heat insulating body.

《Function》 Since the seal ring is buried under pressure in the ceramic wool, which has excellent heat insulation properties, the pores of the ceramic wool above or below the seal ring become soaked and become liquid-tight, improving the heat insulation properties as a whole. It has an excellent liquid-tight sprue structure.

<<Embodiments>> Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

The low-pressure casting device has a mold 1 as shown in Fig. 1.
and a crucible 3 disposed below it and containing the molten metal 2.
It consists of a furnace body 4 that hermetically houses this crucible 3, and a stalk 5 that connects the crucible 3 and the mold 1. Pressurized air is applied to the molten metal 2 in the crucible 3 to raise the molten metal 2 from the stalk 5, and the molten metal is 2 is filled into the mold 1 through the sprue.

In this embodiment, the mold 1 consists of an upper mold 1a, a lower mold 1b, and a slide mold 1c disposed between the upper mold 1a and the lower mold 1b, and is used for filling molten metal 2 to form a casting. The cavity 6 and the core 7 are mainly provided in the slide mold 1c, and a sprue 8 is provided in the lower mold 1b and communicates with the cavity 6.

Further, the mold 1 is sandwiched between an upper platen 9 and a lower platen 10 at its upper and lower sides, and is held between them.

A nichrome wire heater 11 is inserted into the thick part of the peripheral wall of the furnace body 4 located below the mold 1, and is spirally wound and embedded in the peripheral wall. It is sealed. A molten metal 2 made of an alumina alloy is stored in a crucible 3 housed in the furnace body 4, and is turned into a molten metal by heating the furnace body 4. Further, the stalk 5 that connects the crucible 3 and the mold 1 extends upward from the inside of the crucible 3, extends to the upper surface of the lid 12 through an opening provided in the lid 12 corresponding to the stalk 5, and extends to the upper surface of the lid 12. The flange portion 5a is placed on the upper surface of the lid 12 with a packing material 13 interposed therebetween.

Then, the stalk 5 passes through the lower platen 10.
A stalk holder 14 is provided between the upper end and the lower mold 1b of the mold 1, and a portion surrounded by the stalk holder 14 forms a sprue connection portion 15 that connects the sprue 8 and the stalk 5. This connecting portion 15 has a three-layer approximately annular heat insulating body 16 made of ceramic wool.
and a narrow, highly hard seal ring 17 embedded and integrated between them. connected to the opening at the top of the As a result, the stalk 5 and the sprue 8 are communicated with each other, and the molten metal 2 in the crucible 3 is
The structure is such that the liquid reaches the sprue 8 through the stalk 5 and fills the cavity 6 in the mold 1.

To form the sprue connection part 15 as described above,
For example, as shown in FIG.
Three approximately annular heat insulators 16 made of annular ceramic wool, such as glass wool, are stacked on the inside of the insulator, with seal rings 17-17 interposed between them.
The mold 1 is held between the upper platen 9 and the lower platen 10, and the mold 1, together with the upper platen 9 and the lower platen 10, is pressed against the upper end flange 5a of the lower stalk 5. As a result, as shown in FIG. 3, the heat insulator 16 made of ceramic wool is compressed until the lower mold 1b of the mold 1 comes into contact with the upper end of the stalk holder 14, and the seal ring 17
is embedded and integrated in ceramic wool as a heat insulator 16.

At this time, the flange portion 5a at the upper end of the stalk 5 is hermetically attached to the upper surface of the lid 12 via the packing material 13, so that the furnace body 4 is hermetically sealed.

The heat insulating body 16 made of ceramic wool has a porosity of 80-85%, and in the above embodiment the thickness is compressed to 2/3, but preferably the thickness is compressed to about 1/3. It is to be. In this case, it goes without saying that the height of the stalk presser should be equal to the height of one layer of ceramic wool laminated in three layers.

By being compressed in this way, the seal ring is embedded in the ceramic wool, and the ceramic wool parts directly above and below the seal ring are compressed more than other parts and become extremely dense, making them insensitive to the molten metal. Becomes transparent.

In the above embodiment, the heat insulating body made of ceramic wool is compressed after being attached between the mold and the stalk, but the heat insulating body may be compressed in advance and then attached.

<<Effects>> As described above, according to the sprue structure of the low-pressure casting apparatus of the present invention, the sprue joint between the stalk and the sprue is formed by a plurality of heat insulators made of ceramic wool and a seal ring interposed between the heat insulators. It is constructed as a laminate, and by pressurizing this laminate, the seal ring is embedded and integrated into the heat insulator, so the connecting part between the stalk of the low-pressure casting machine and the sprue of the mold has an effective heat insulation effect. By controlling the solidification state of the molten metal in this area, it is possible to prevent the progress of solidification of the molten metal into the stalk, the blockage of the sprue due to the solidification of the molten metal, and the conduction of heat to the mold. The ceramic wool in between is compressed and becomes extremely dense, making this part impermeable to molten metal, so there is no risk of molten metal penetrating into the joint, and its construction is simple and low cost. Become.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view of the low-pressure casting apparatus according to the present invention, Figure 2 is an enlarged sectional view of the main part of the connection between the mold and sprue, and Figure 3 is a state in which the connection is compressed from the state shown in Figure 2. FIG. 2 is an enlarged sectional view of main parts. 1... Mold, 2... Molten metal, 5... Stoke, 8
... sprue, 15 ... sprue connection section, 16 ... heat insulator, 17 ... seal ring.

Claims (1)

[Scope of utility model registration request] In the sprue structure of a low-pressure casting device that applies pressure to the molten metal to raise the molten metal from a stalk, and fills the molten metal into a mold through the sprue to form a casting,
A sprue connecting portion between the stalk and the sprue is constructed as a laminate of a plurality of heat insulators made of ceramic wool and a seal ring interposed between the heat insulators,
A sprue structure for a low-pressure casting device, characterized in that the seal ring is embedded and integrally attached to the heat insulator by pressurizing the laminate.