1986 Fiscal Year Final Research Report Summary
A Study on the Metal Flow in Dental Casting -The Trial to Measure the Casting Velocity by Electromagnetic Flowmeter-
| Project/Area Number |
59570825
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
補綴理工系歯学
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| Research Institution | Tohoku Dental University |
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Principal Investigator |
ETCHU Yasashi Tohoku Dental University,Faculty of Dentistry,Assistant-Prof., 歯学部, 助教授 (10094939)
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| Project Period (FY) |
1984 – 1986
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| Keywords | Dental casting / Casting process / Casting velocity / Electromagnetic flowmeter / Gas pressure casting / Mercury / Silver-Tin alloy / 埋没材 |
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| Research Abstract |
This study aimed to devise a flowmeter capable of measuring casting velocities both continuously and quantitatively, for the purpose of studying process of molten alloy in the dental casting. At first, flowmeters were made by applying electromagnetic flowmeter method, and they were tested if they would function as velocity sensors by calibrating with practical flow. Then, the flowmeters were used to measure casting velocities in gas-pressure casting, centrifugal casting, and vacuum-pressure casting.
1. Flowmeters
Three types of flowmeters were devised.
1) Premanent magnet-integrated flowmeter for mercury(IF)
2) Premanent magnet-separated flowmeter for silver-tin alloy (SF)
3) Solenoidal magent flowmeter (SMF) Good correlation between the flow velocity and the generated electricity was observed when IF and SF were used. So, IF and SF were considered to suit for the measurment. However, in the use of SMF, the magnetic field was small as about 10-20% of IF and SF, and the measurement was unsta
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ble because of heating. Therefore, SMF was of no practical use.
2. Practical application of flowmeters to gas-pressure casting
Casting velocities in gas-pressure casting were measured with the above metioned IF and SF. Results were as follows;
1) The casting proceeded in two stages.
2) At the first stage, the casting velocity increased accompanying with the increase in casting pressure, reached the peak when the casting pressure achieved the plateau, and descended. Duration of this process was long when gypsum-bonded investment was used, but it was short when phosphate-bonded investment was used.
3) At the second stage, the casting fluctuated if gypsum-bonded investment was used. On the other hand, in phosphate-bonded investment, the casting prolonged at a constant low velocity.
4) The maximum casting velocity in the first stage got higher if the tank gas pressure was raised.
5) In gypsum-bonded investment, there found no significant difference among the casting times in the tank pressure range from 0.6 to 1.2 kgf/ <cm^2> .
3. Practical application of flowmeters to the other castings
Next, the flowmeters were applied to centrifugal casting and vacuum-pressure casting. In centrifugal casting, however, the recording was interrupted by separation of the molten metal from the electrode during casting. And in vacuum-pressure casting, the recording was hindered by externally originated electrical noise. It remained to improve the flowmeters for optimum recording. Less
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