11-07-2013 дата публикации
Номер: US20130174996A1
Various techniques are provided for creating fugitive foam patterns for use in investment casting operations. In certain illustrative embodiments, a fugitive foam pattern is assembled from independently formed portions. A first section is formed in a mold. Once cured, a mating surface of the first section is exposed to the cavity of a second mold and the section is formed. The second section integrally adheres to the first section. The process is repeated as necessary. In alternative embodiments, a channel is created in a foam pattern using a temporary core that is removed without chemical leaching. The core material comprises water-soluble materials, acid-soluble materials, low-melting point materials, or a combination thereof. A pattern may also be created by inserting foam around a core that remains with the foam pattern. 1. A method of assembling a fugitive foam pattern , the method comprising:inserting a mixture comprising polyol and isocyanate into a mold cavity of a first mold corresponding to a first portion the foam pattern;waiting for a predetermined time sufficient for a first reaction from the mixture to form a foam pattern structure corresponding to the first portion of the foam pattern, wherein the first portion includes a mating surface;exposing the mating surface of the first portion of the foam pattern structure to a mold cavity of a second mold corresponding to a second portion of the foam pattern;inserting the mixture into the mold cavity of the second mold corresponding to the second portion the foam pattern; andwaiting for a predetermined time sufficient for a second reaction from the mixture to form a foam pattern structure corresponding to the second portion of the foam pattern such that the second reaction bonds the second portion to the mating surface of the first portion of the foam pattern structure.2. The method of claim 1 , wherein exposing the mating surface of the first portion comprises removing the foam pattern structure ...
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