Vacuum Casting Mold Valve Timing for Seal Reliability
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Solution Overview
Problem
Foreign matter, such as powder burrs, tends to adhere to and get caught in the seal portion of the shut-off valve during the preheating shot in casting processes, leading to sealing failures and interference with the flow of molten metal in vacuum casting.
Innovation Solution
A heating method for a casting mold that involves a sequence of gas suction steps to control pressures within the casting mold, including a first and second suction step during casting, and a third and fourth suction step during preheating, with specific time periods for valve opening to prevent foreign matter adhesion and ensure proper filling of the overflow portion with molten metal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mold is not sufficiently heated during preheating shot, then the preheating process can be completed faster, but powder burrs occur and adhere to the shut-off valve seal portion
Solution Approach 1:
The patent applies preliminary action by performing a gas suction operation before the preheating shot to remove powder burrs from the overflow portion and gas flow path in advance. This prevents the powder burrs from adhering to the shut-off valve seal portion during subsequent operations, thereby maintaining sealing reliability without sacrificing preheating speed
Solution Approach 2:
The patent implements skipping by reducing the valve opening time during preheating shot compared to normal casting. By opening the shut-off valve only briefly just enough to allow molten metal to fill the overflow portion and confirm complete release, the patent rushes through the critical phase where powder burr adhesion could occur, thus maintaining productivity while preventing sealing failures
2Manufacturing precision
If the valve is opened for a long time during preheating shot, then the overflow portion can be filled with molten metal, but foreign matter adheres to the shut-off valve
Solution Approach 1:
The patent performs gas suction before preheating shot to remove powder burrs from the overflow portion and gas flow path in advance. This preliminary cleaning action ensures that even when the valve is opened for filling, there is minimal foreign matter available to adhere to the shut-off valve seal portion
Solution Approach 2:
The patent applies partial action by opening the shut-off valve only for the minimum necessary time during preheating shot - just enough to allow molten metal to fill the overflow portion and confirm complete cast article release. This reduced valve opening time limits exposure to foreign matter while still achieving the necessary filling
3Manufacturing precision
If gas suction is performed at near vacuum during preheating shot, then the overflow portion fills with molten metal, but powder burrs are generated and caught in the shut-off valve
Solution Approach 1:
The patent performs gas suction at near vacuum before the preheating shot to remove powder burrs from the overflow portion and gas flow path. By conducting this cleaning operation beforehand, the patent prevents powder burrs from being generated and caught in the shut-off valve during subsequent preheating operations
Solution Approach 2:
The patent dynamically adjusts the gas suction pressure conditions based on the operation phase. During preheating shot, gas suction is performed at atmospheric pressure rather than near vacuum, while still achieving adequate filling by controlling valve timing. This dynamic adjustment prevents powder burr generation while maintaining filling accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively prevents foreign matter from adhering to the shut-off valve, ensuring a reliable seal and efficient filling of the overflow portion, thereby reducing defects and improving the preheating process efficiency.
Implementation Method 1
a first suction step of setting a pressure in the gas flow path to a predetermined pressure by sucking gas in the gas flow path
Implementation Method 2
In the vacuum casting, casting is performed after gas in the cavity is sucked. Therefore, in the vacuum casting, the mold is sealed in order to prevent air from leaking into the cavity.
Data Source
AI summary
A casting mold is provided with a cavity portion and an overflow portion, and the overflow portion is connected to a gas flow path (suction path). A valve (an on-off valve, a shut-off valve) is provided between the gas flow path and the overflow portion. A heating method for a casting mold includes a step of setting the pressure in the cavity portion to a second pressure by sucking gas in the overflow portion and in the cavity portion while the valve is kept open for a second time period shorter than a first time period during casting. The heating method further includes a step of heating the casting mold by supplying molten metal into the cavity portion set at the second pressure, and solidifying the molten metal.