Method for the manufacture of molds using casting sand or another mixture of raw material particles
First Claim
1. A method for manufacturing molds from casting sand or other mixture comprising raw material particles, binder and water, by applying a pressure surge wave to said casting sand or other mixture in a closed chamber, said pressure surge wave being formed by a process comprising the steps of:
- (a) starting from atmospheric pressure in said chamber, increasing said pressure with a pressure gradient of at least about 50 atmospheres/sec to a maximum pressure of at least about 2 atmospheres;
(b) maintaining said maximum pressure of at least about 2 atmospheres for at least about 0.01 seconds;
(c) reducing said pressure from said maximum pressure to atmospheric pressure within at least about 0.2 seconds from the initiation of the pressure increase.
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Accused Products
Abstract
In order to make castings from casting sand or another moldable mixture, a pressure surge wave is used which has upper and lower limit values which values have been established by an optimal selection of a pattern of pressures. The other moldable mixture comprises particles of raw material, binder, water, and, if need be, additives. The rise in pressure takes place with an increasing pressure gradient, dp/dt, of at least 50 atmospheres (absolute)/second. A minimum pressure of at least 2 atmospheres (absolute) is maintained for at least 0.01 second. The pressure drop takes place at a decreasing pressure gradient, -dp/dt, of up to about 2.0 atmospheres (absolute)/second. The disclosed values represent an optimalization, in view of a simple design and economy of operation, with a surprisingly good compacting.
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Citations
13 Claims
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1. A method for manufacturing molds from casting sand or other mixture comprising raw material particles, binder and water, by applying a pressure surge wave to said casting sand or other mixture in a closed chamber, said pressure surge wave being formed by a process comprising the steps of:
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(a) starting from atmospheric pressure in said chamber, increasing said pressure with a pressure gradient of at least about 50 atmospheres/sec to a maximum pressure of at least about 2 atmospheres; (b) maintaining said maximum pressure of at least about 2 atmospheres for at least about 0.01 seconds; (c) reducing said pressure from said maximum pressure to atmospheric pressure within at least about 0.2 seconds from the initiation of the pressure increase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification
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- Resources
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Current AssigneeGeorge Fischer Foundry Systems, Inc.
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Original AssigneeGeorg Fischer AG
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InventorsLandolt, Christoph
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Primary Examiner(s)Lin, Kuang Y.
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Application NumberUS06/531,827Time in Patent Office796 DaysField of Search164/12, 164/15, 164/169, 164/195, 164/37, 164/38-40US Class Current164/37CPC Class CodesB22C 15/00 Moulding machines character...
