Investment casting utilizing patterns produced by stereolithography
First Claim
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1. A method of investment casting comprising the steps of:
- (a) investing a three-dimensional pattern in a mold material, said pattern being constituted by a cross-linked polymeric matrix constituted by light-cured ethylenically unsaturated material having dispersed therein a thermoplastic material having a melting temperature below about 100°
C., and being non-reactive with said ethylenically unsaturated material;
(b) and heating said mold material with said pattern within it to fuse the material of said mold and to burn said pattern out of said mold, said non-reactive material weakening said pattern during the heating operation to prevent the thermal expansion of said pattern from cracking said mold.
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Abstract
A method of investment casting utilizes a pattern produced by stereolithography in which a three-dimensional specimen is provided by light cure of ethylenically unsaturated liquid material. The stereolithography composition is constituted by the ethylenically unsaturated liquid material in admixture with an inert low thermoplastic material which weakens the pattern when heated within the mold used in the investment casting process to prevent the thermal expansion of the pattern from cracking the mold.
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Citations
18 Claims
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1. A method of investment casting comprising the steps of:
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(a) investing a three-dimensional pattern in a mold material, said pattern being constituted by a cross-linked polymeric matrix constituted by light-cured ethylenically unsaturated material having dispersed therein a thermoplastic material having a melting temperature below about 100°
C., and being non-reactive with said ethylenically unsaturated material;(b) and heating said mold material with said pattern within it to fuse the material of said mold and to burn said pattern out of said mold, said non-reactive material weakening said pattern during the heating operation to prevent the thermal expansion of said pattern from cracking said mold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of investment casting comprising the steps of:
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(a) exposing a thin layer of light-curable, organic solvent-free, ethylenically unsaturated liquid to a light source to cause polymerization of selected portions of said thin layer, said ethylenically unsaturated liquid including from about 5% to about 40% of a thermoplastic material having a melting temperature below about 100°
C., and being non-reactive with said ethylenically unsaturated material;(b) covering the said polymerized layer with a layer of said light-curable liquid composition; (c) exposing the uncured layer to the light source to polymerize selected portions of the uncured layer upon the previously set forth polymerized layer; (d) repeating steps (b) and (c) to produce a specimen; (e) completing the cure of said specimen to produce a pattern; (e) investing said pattern in a mold material and (f) heating the pattern and mold material to remove the pattern and fuse the mold material to produce a mold. - View Dependent Claims (15, 16, 17, 18)
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Specification