Vertical Casting Apparatus and Vertical Casting Method

Abstract

The present invention is to provide a vertical casting apparatus capable of easily manufacturing castings without causing shrinkage cavities and entrainment of gas, by filling a molten metal into a mold cavity at a high speed and by effectively pressurizing the molten metal in the closed cavity, which has high work efficiency, ease of maintenance, and a low cost of equipment, and a vertical casting method using the vertical casting apparatus. The vertical casting apparatus is provided with an apparatus body comprising a fixed mold 1 on the lower side and a movable mold 2 on the upper side, a closing means 13 for closing a molten metal in-flow gate 10 formed in the fixed mold 1, and a pressurizing means 20 for pressurizing the molten metal in the closed mold cavity, and a casting means for supplying and filling the molten metal into the mold cavity from the underside. The casting means has a gas-pressurized molten metal pouring ladle 6 attachable to and detachable from the apparatus body.

Description

TECHNICAL FIELD [0001] The present invention relates to a vertical casting apparatus capable of manufacturing castings such as aluminum alloys, in which a molten metal is filled into a mold cavity from underside, and, more particularly, to a vertical casting apparatus in which a molten metal is supplied and filled into a mold cavity from the underside by using a gas-pressurized molten metal pouring ladle, and a vertical casting method using the vertical casting apparatus. BACKGROUND ART [0002] In the case where castings such as light alloy products, especially parts requiring strength, are manufactured, a vertical casting apparatus are used to prevent entrainment of gas at the time when molten metal is poured. [0003] In such a vertical casting apparatus, as a means for supplying molten metal into a mold cavity from a molten metal holding furnace while preventing the mixing of oxides and the entrainment of gas, use of a low-pressure gas is already known (see Japanese Laid-Open Patent...

AI Technical Summary

Benefits of technology

[0007] In casting using a vertical casting apparatus, in order to manufacture high-quality castings, especially thin-wall and large-size castings, it is necessary to fill molten metal into the mold cavity at a high speed. Also, in order to prevent the mixing of oxides and the entrainment of gas, which cause defects of castings, and to prevent shrinkage cavities produced by solidification shrinkage, it is necessary to fill molten metal from underside and to replenish a sufficient amount of molten metal by pressurizing effectively. Also, at this time, to reduce troubles during operation, it is necessary to simplify the construction of cavity and of the whole casting apparatus, for practical use. High work efficiency and ease of maintenance are also very important factors.

[0008] An object of the present invention is to provide a vertical casting apparatus capable of easily manufacturing castings without causing shrinkage cavities and entrainment of gas by filling molten metal into a mold cavity at a high speed and effectively pressurizing the molten metal in the closed cavity, which has high work efficiency, ease of maintenance, and a low cost of equipment, and a vertical casting method using the vertical casting apparatus. MEANS TO SOLVE THE OBJECT

[0009] The present inventors earnestly conducted studies to solve the above objects, and found out that by using an apparatus body and a gas-pressurized molten metal pouring ladle attachable to and detachable from the apparatus body, a vertical casting apparatus having high work efficiency, ease of maintenance, and a low cost of equipment can be provided, and by increasing the gas pressure in the gas-pressurized molten metal pouring ladle, molten metal can be supplied at a high speed, by which a casting without the mixing of oxide film and the entrainment of gas can be manufactured, leading to the completion of the present invention. Further, the present inventors found out that after the cavity has been filled with the poured molten metal, if the molten metal in the closed state is effectively pressurized at a plurality of places with the pressure transmission distance being short, a casting can be manufactured without causing shrinkage cavities, mixing of oxide film, and entrainment of gas, leading to the completion of the present invention.

[0011] Further, the present invention relates to (10) a vertical casting method using the vertical casting apparatus according to any one of (1) to (9), comprising the steps of casting a molten metal into the mold cavity from the gas-pressurized molten metal pouring ladle through the casting stoke; and closing the molten metal in-flow gate formed in the fixed mold by the closing means after the molten metal has been filled into the cavity; and subsequently pressurizing the molten metal in the mold cavity by a pressurizing means; (11) the vertical casting method according to (10), comprising the steps of releasing immediately the gas pressure in the gas-pressurized molten metal pouring ladle to the atmosphere, and detaching the gas-pressurized molten metal pouring ladle from the apparatus body, after closing the molten metal in-flow gate by the closing means; supplying a molten metal necessary for the next cycle into the gas-pressurized molten metal pouring ladle; and attaching again the gas-pressurized molten metal pouring ladle to the apparatus body to provide for the next casting operation; (12) the vertical casting method according to (10) or (11), wherein the gas pressure in the gas-pressurized molten metal pouring ladle is regulated to be 1 kg / cm2 or higher to perform casting at a high speed in a short period of time; and (13) the vertical casting method according to (10) to (12), wherein the casting is a thin-wall and large-size casting of a light metal alloy.

Problems solved by technology

However, although the low-pressure gas is effective in supplying molten metal quantitatively into a mold, only the use of low-pressure gas is not sufficient to avoid shrinkage cavities occurring at the time of solidification of molten metal and defective thin-wall products because the casting speed is slow and the pressure is low.

Also, in a conventional apparatus, a large amount of molten metal was accommodated in a molten metal holding furnace fixed to an apparatus body, which increased the size of apparatus.

Further, it is not easy to replenish molten metal into the molten metal holding furnace fixed to the apparatus body, and also it is very difficult to perform spraying work for cleaning and lubricating an in-flow gate of the apparatus body.

However, the apparatus for carrying out this method also increases in size because high-speed casting requires a large electromagnetic pump.

Therefore, the practical use of this apparatus is difficult, and additionally, they had the same problems as described above, such as the difficulty in replenishing molten metal.

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