Casting method and casting device

• US 10,441,998 B2
• Filed: 03/04/2015
• Issued: 10/15/2019
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Masuta, Tatsuya, Ota, Shunsuke
• Primary Examiner(s): Kerns, Kevin P
• Application Number:
  US15/129,204
• Publication Number:
  US 20180178276A1
• Time in Patent Office: 1,686 Days
• Field of Search: 164457, 164254, 164255, 164256, 164257, 164258, 164 61, 164 63, 164 65, 164119, 164306
• CPC Class Codes: B22D 18/04 Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
• CPC Class Codes: B22D 18/08 Controlling, supervising, e.g. for safety reasons controlling or regulating in general G05

Abstract

Molten metal M is raised to the vicinity of a gate 11 of a cavity 9C by increasing the pressure in a holding furnace 5 with gas, and thereafter the cavity 9C is filled with the molten metal M by decreasing the pressure in the cavity 9C by suction and further increasing the pressure in the holding furnace 5. Thereafter, the decompression of the cavity 9C is stopped after a preset filling time, and the compression of the holding furnace 5 is stopped when solidification of the molten metal M is completed. In this way, the suction is minimized, and it becomes possible to employ a simple decompression part 14. A reduction in equipment cost and production cost is thereby achieved, and a reduction in casting cycle time is also achieved.

Claims

1. A casting method for molding a product based on low-pressure casting by using a casting device in which a mold with a cavity is disposed over a holding furnace storing molten metal, comprising the steps of:

raising the molten metal to a vicinity of a gate of the cavity by increasing a pressure in the holding furnace and thereafter filling the cavity with the molten metal by decreasing a pressure in the cavity by suction and simultaneously further increasing pressure applied to the holding furnace to increase the pressure in the holding furnace;

stopping decompression of the cavity after a preset filling time; and

stopping compression of the holding furnace when solidification of the molten metal is completed, and

wherein in the step of filling the cavity with the molten metal by decreasing the pressure in the cavity by suction and simultaneously further increasing pressure applied to the holding furnace, the pressure of the holding furnace increases more rapidly than during the step of raising the molten metal to the vicinity of the gate of the cavity by increasing the pressure in the holding furnace.

2. The casting method according to claim 1, further comprising the steps of:

using a molten metal sensor for detecting completion of filling the cavity with the molten metal; and

stopping decompression of the cavity when the molten metal sensor detects completion of filling with the molten metal within the preset filling time.

3. The casting method of claim 1, further comprising:

providing a plurality of casting units, each comprising a holding furnace configured to store molten metal, a mold with a cavity and a compression part configured to increase a pressure in the holding furnace; and

providing a decompression part configured to decrease a pressure in the cavity of each of the plurality of casting units by suction,

wherein the decompression part comprises a vacuum tank with a suction pipe at an inlet side and a discharge pipe at an outlet side, a vacuum pump connected to the discharge pipe of the vacuum tank, branch pipes that are branched from the suction pipe of the vacuum tank and are respectively communicated with the cavity of each of the plurality of casting units and on-off valves configured to open and close the respective branch pipes.

4. The casting method according to claim 3, wherein the cavity of the mold is a casting space configured for molding a suspension member of a car.

5. The casting method according to claim 3, wherein the cavity of the mold is a casting space configured for molding a cylinder head of an internal combustion engine.

6. The casting device method according to claim 3, wherein the cavity of the mold is a casting space configured for molding a motor case.

7. A casting method for molding a product based on low-pressure casting by using a casting device in which a mold with a cavity is disposed over a holding furnace storing molten metal, comprising the steps of:

raising the molten metal to a vicinity of a gate of the cavity by increasing a pressure in the holding furnace and thereafter filling the cavity with the molten metal by decreasing a pressure in the cavity by suction and simultaneously further increasing pressure applied to the holding furnace to increase the pressure in the holding furnace;

stopping decompression of the cavity after a preset filling time; and

stopping compression of the holding furnace when solidification of the molten metal is completed,

wherein a first rate at which the pressure in the holding furnace increases during the step of raising the molten metal to the vicinity of the gate of the cavity is slower than a second rate at which the pressure in the holding furnace increases during the step of filling the cavity with the molten metal by decreasing the pressure in the cavity by suction and simultaneously further increasing pressure applied to the holding furnace.

8. The casting method according to claim 7, further comprising the steps of:

using a molten metal sensor for detecting completion of filling the cavity with the molten metal; and

stopping decompression of the cavity when the molten metal sensor detects completion of filling with the molten metal within the preset filling time.

9. The casting method of claim 7, further comprising:

providing a plurality of casting units, each comprising a holding furnace configured to store molten metal, a mold with a cavity and a compression part configured to increase a pressure in the holding furnace; and

providing a decompression part configured to decrease a pressure in the cavity of each of the plurality of casting units by suction,

wherein the decompression part comprises a vacuum tank with a suction pipe at an inlet side and a discharge pipe at an outlet side, a vacuum pump connected to the discharge pipe of the vacuum tank, branch pipes that are branched from the suction pipe of the vacuum tank and are respectively communicated with the cavity of each of the plurality of casting units and on-off valves configured to open and close the respective branch pipes.