JP2019098361A - Low pressure casting method - Google Patents

Abstract

To provide a low pressure casting method capable of suppressing the deterioration of releasability from a gate insert of a product.SOLUTION: Provided is a low pressure casting method comprising: a filling step where a molten metal M is filled to a mold 16 via a gate insert 13; a solidified part S formation step where the molten metal M is cooled in a prescribed part of the gate insert 13 to partially solidify the same; a gas injection step where a gas is injected to the gate insert 13 from a lower part of a cooling position; and a molten metal pushing-out step where the solidified part S is pushed above the inside of the gate insert 13 by the pressure of the gas injected below the solidified part S, and the molten metal is pushed out.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a low pressure casting method.

  As a low pressure casting method, there is known a method using a low pressure casting apparatus provided with a mold having one molten metal holding furnace and a plurality of crucibles, and provided with inert gas supply means for each crucible. In Patent Document 1, when the pouring of water into the mold is completed, an inert gas is injected into the inserter, and the molten metal is separated from the product portion by the pressure of the injected inert gas. There is disclosed a method for draining a low pressure casting apparatus.

JP 2001-287015 A

  When the molten metal is poured into the mold, a pouring process is performed to apply a casting pressure from the stalk side via the inserter to prevent the generation of the cavities. However, when the hot water is poured for a long time, there is a problem that solidification of the molten metal in the core portion progresses too much, and the releasability from the core of the product is deteriorated.

  The present invention has been made in view of the above problems, and provides a low-pressure casting method capable of suppressing the deterioration of the releasability of the product from the insert.

  The low-pressure casting method according to the present invention comprises a filling step of filling a molten metal into a mold through a crucible, a solidified portion forming step of cooling the molten metal at a predetermined portion of the crucible and partially solidifying the molten metal. The gas injection step of injecting a gas into the insulator from below the cooling position, and the pressure of the gas injected below the coagulating portion pushes the coagulating portion upward in the insulator. And a pressing process for performing a pressing process.

  In the low pressure casting method according to the present invention, the solidified portion is formed by cooling, and the solidified portion is pushed up above the inside of the inserter by the pressure of the gas injected below the solidified portion to perform pouring. , You can secure a long time for hot water. Therefore, the deterioration of the releasability of the product from the insert can be suppressed.

  According to the present invention, in low pressure casting, it is possible to suppress the deterioration of the releasability of the product from the insert.

It is a flowchart which shows a series of flows of the low pressure casting method concerning embodiment. It is a schematic sectional drawing which shows the process of filling a molten metal in a metal | mold via a crucible using the low pressure casting device concerning embodiment. It is an enlarged view of area | region III shown with the broken line of FIG.

Embodiment
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a flowchart showing a series of flows of the low pressure casting method according to the embodiment. First, a molten metal is filled into a mold through an inserter (step S1). Next, the molten metal is cooled at a predetermined portion of the inserter and partially solidified (step S2). Next, a gas is injected into the insert from below the molten metal cooling position (step S3). Then, the coagulating part is pushed up above the inserter by the pressure of the gas injected below the coagulating part to carry out the pouring (step S4). After the step S4, the hot water is released, the mold is opened, and the product is taken out.

Next, each step will be described in detail with reference to FIG. 2 and FIG. 3 corresponding to a part of the flowchart of FIG.
<Step S1: Molten metal filling>
In step S1, the molten metal is filled into the mold through the inserter.
FIG. 2 is a schematic cross-sectional view showing a filling step of filling the molten metal M into the cavity C of the mold 16 through the insert 13 using the low pressure casting apparatus 1 according to the embodiment. In the present embodiment, the molten metal M is, for example, a molten metal of aluminum, and is supplied from the lower portion to the upper portion of the low pressure casting device 1. First, the molten metal M is pushed up from the molten metal holding furnace (not shown) which accommodates the molten metal M via the stoke 11 which is a hot water supply pipe. Further, the pushed-up molten metal M is filled into the cavity C of the mold 16 through the spigot insert 12 and the insert insert 13. The insulator 13 includes a cooling unit 14 for cooling the molten metal M, and a gas supply unit 15 for supplying a gas into the insulator.

<Step S2: Solidification Part Formation>
In step S2, the molten metal M is cooled at a predetermined portion of the insulator 13 and partially solidified.
FIG. 3 is an enlarged view of a region III indicated by a chain line in FIG. 2 and is a schematic cross-sectional view showing a state where the molten metal M is cooled at a predetermined portion of the inserter 13 and partially solidified. The pushed-up molten metal M is cooled by the cooling unit 14, and at least a part of the molten metal M solidifies, and the formation of the solidified unit S is started.

  In the present embodiment, as shown in FIG. 3, the cylindrical cooling portion 14 is disposed at the neck portion of the insulator 13, but the position of the cooling portion 14 is not limited to this. For example, it is possible to arrange the cooling unit 14 in the upper part of the insert 13 and at a position closer to the mold, or conversely, in the lower part of the insert 13 and cool away from the mold. It is also possible to arrange the part 14. For example, a cooling pipe (water cooling or air cooling) or the like can be used as the cooling unit 14.

<Step S3: Gas Injection>
Step S3 is performed while continuing cooling of the molten metal M in step S2.
In step S3, a gas is injected from below the cooling position of the molten metal M to the insulator 13.
As shown in FIG. 3, the supply port 15 a of the gas supply unit 15 for injecting a gas into the insulator is disposed below the cooling unit 14. That is, the gas is injected below the coagulating portion S through the supply port 15a (black arrow). As a gas injected into the insulator 13, for example, an inert gas can be used.

  Moreover, it is preferable that the supply port 15a of the gas supply part 15 has a plurality of holes of about 0.1 to 0.2 mm, for example, on the side surface or the like. By providing a plurality of holes in the supply port 15a, an inert gas can be passed while preventing the entry of the molten metal. For example, sintered vent (registered trademark) can be used as the supply port 15a.

<Step S4: Boiled water>
By the cooling of the molten metal M, which has been performed continuously from step S2, the solidified portion S has a plate-like shape.
In step S4, the coagulating portion S is pushed up above the insert 13 by the pressure of the gas injected below the coagulating portion S and the hot water is poured.
As shown in FIG. 3, the solidified portion S having a shape close to a plate shape is pushed up above the insert 13 by the pressure of the gas injected below the solidified portion S, and the pouring water is Done (open arrow). That is, the molten metal M in the crucible 13 is separated into the upper side above the solidification part S and the lower side than the supply port 15 a of the gas supply part 15 by the injection of the gas.

  It is preferable that the pressure of the gas at this time be a pressure larger than the pressure in the case of performing the hot water without forming the solidified portion S. Further, the molten metal M separated in the lower part of the insert 13 is not solidified by the cooling by the cooling unit 14 because the molten metal M is maintained by the heat conduction transmitted from the molten metal holding furnace through the stalk and the sprue insert. . In addition, when performing pouring by gas, gas does not penetrate the coagulation | solidification part S. FIG.

  In the present embodiment, the solidification time until the solidification section S having a shape close to a plate is formed after the formation of the solidification section S by cooling the molten metal M is measured in advance, and the solidification time is a gas supply time And By supplying gas from the start of solidification of the molten metal M, the pouring can be performed for a longer time. In addition, after the coagulation | solidification part S which has a shape close | similar to plate shape is formed, gas can be inject | poured and pouring can also be performed.

After completion of step S4, the hot water is released, the mold is opened, and the product P is taken out.
The above is a series of flows of the low pressure casting method according to the present embodiment.

  As in the prior art, in the pouring process in which the casting pressure is applied through the inserter, it takes a long time for the pouring process. When the hot water is poured for a long time, there is a problem that solidification of the molten metal in the core portion progresses too much, and the releasability from the core of the product is deteriorated.

  In the present embodiment, the molten metal is filled into the mold through the insulator, the molten metal is cooled at a predetermined portion of the insulator, partially solidified, and the gas is introduced into the insulator from below the cooling position. The coagulated part is pushed up to the upper part in the inserter by the pressure of the gas injected and injected into the lower part of the coagulated part, and the hot water is poured. When the molten metal is solidified using the cooling unit, the solidified portion can be formed in a shorter time than the normal solidification time, and therefore, the time of the pouring can be secured long. And by using the said coagulation | solidification part for a pouring bath, mold release property can be improved and the quality of a product can be improved. In addition, when the molten metal in the crucible is solidified using the cooling unit and an inert gas is injected, the molten metal in the crucible can be separated up and down. Therefore, it is also possible to prevent the progress of directional solidification to the lower side of the insulator.

  The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the scope of the present invention.

1: Low pressure casting apparatus 11: Stoke 12: Spout insert 13: Insert insert 14: Cooling section 15: Gas supply section 15a: Supply port 16: Mold C: Cavity G: Inert gas M: Molten metal P: Product S1 , S2, S3: step

Claims (1)

A filling step of filling the molten metal into the mold through the inserter,
A solidified portion forming step of cooling the molten metal at a predetermined portion of the insulator and partially solidifying the molten metal;
A gas injection step of injecting a gas into the insulator from below the cooling position;
The method further includes the step of pushing the coagulating portion upward in the inserter by the pressure of the gas injected to the lower side of the coagulating portion, and performing a pouring step.
Low pressure casting method.

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