Stereolithography using repeated exposures to increase strength and reduce distortion

• US 4,945,032 A
• Filed: 10/31/1989
• Issued: 07/31/1990
• Est. Priority Date: 03/31/1988
• Status: Expired due to Fees

• Current Assignee: DSM Resins BV (DSM-Firmenich AG)
• Original Assignee: DeSoto, Inc. (Overstock.com Incorporated)
• Inventors: Murphy, Edward J., Krajewski, John J., Ansel, Robert E.
• Primary Examiner(s): Robinson, Ellis P.
• Assistant Examiner(s): Loney, Donald J.
• Application Number:
  US07/429,561
• Time in Patent Office: 273 Days
• Field of Search: 264/1.1, 264/1.4, 264/1.6, 264/1.7, 264/2.2, 264/22, 264/24, 264/183, 264/40.1, 365/119, 365/120, 425/174, 425/14.8, 425/23, 425/162, 425/425, 430/321, 430/327, 430/329, 430/394, 427/54.1, 427/53.1, 42/269, 42/945, 42/322, 42/325, 42/328
• US Class Current: 264/401
• CPC Class Codes: B29C 64/135 the energy source being concentrated, e.g. scanning lasers or focused light sources
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: G03F 7/0037 Production of three-dimensional images
• CPC Class Codes: Y10S 430/146 Laser beam

Abstract

An improved stereolithographic process is provided in which the formation of a thin walled three-dimensional object in a reservoir of liquid ultraviolet-curable ethylenically unsaturated material using a support is positioned immediately beneath the upper surface of the liquid reservoir with that upper surface being exposed to ultraviolet light in a pattern to solidify the liquid at and near the upper surface in a series of cross-sections of the desired three-dimensional object, one atop the other. In this way there is formed a series of superposed layers which adhere to one another to build the desired three-dimensional object within the liquid reservoir. The improvement comprises, stopping the exposure at any portion of the surface in the formation of said layers and then repeating the exposure at least once again in the production of each surface layer so that the strength and solvent resistance of the formed object are increased and its distortion is minimized. The ultraviolet exposure of each surface layer is preferably carried out as a series of rapid repeated scans of a computer-directed focused laser.

Claims

1. In a method for the formation of a thin walled three-dimensional object in a reservoir of liquid ultraviolet-curable ethylenically unsaturated material and in which a support is positioned immediately beneath the upper surface of the liquid reservoir with said upper surface being exposed to ultraviolet light in a pattern of line exposures to solidify the liquid at and near said upper surface in a series of cross-sections of the desired three-dimensional object, one atop the other, and thus form a series of superposed layers which adhere to one another to build said three-dimensional object within the liquid reservoir, the improvement comprising, stopping the line exposure at any portion of the surface in the formation of said series of superposed layers and then repeating the line exposure at least once again in the production of each said superposed layer so that the strength and solvent resistance of the formed object are increased and its distortion is minimized.

2. The improvement recited in claim 1 in which the ultraviolet exposure of each surface layer is carried out as a series of rapid repeated scans of a computerdirected focused laser.

3. The improvement recited in claim 1 in which said liquid ultraviolet-curable ethylenically unsaturated material comprises acrylate-functional material to speed the ultraviolet-initiated cure.

4. The improvement recited in claim 1 in which said liquid ultraviolet-curable ethylenically unsaturated material is a free flowing liquid to ease the burden of flowing said liquid over each solidified layer in preparation for the formation of the next layer.

5. In a method for the formation of a three-dimensional object in a reservoir of liquid ultraviolet-curable ethylenically unsaturated material and in which a support is positioned immediately beneath the upper surface of the liquid reservoir with said upper surface being exposed to light effective to polymerize said ehtylenically unsaturated material in a pattern of line exposures to solidify the liquid at and near said upper surface in a series of cross-sections of the desired three-dimensional object, one atop the other, and thus form a series of superposed layers which adhere to one another to build said three-dimensional object within the liquid reservoir, the improvement comprising, stopping the line exposure at any portion of the surface in the formation of said series of superposed layers and then repeating the line exposure at least once again in the production of each said superposed layer so that the strength and solvent resistance of the formed object are increased and its distortion is minimized.

6. The improvement recited in claim 5 in which the light exposure of each surface layer is carried out as a series of rapid repeated scans of a computer-directed focused laser.