Thermal control of selective laser sintering via control of the laser scan
First Claim
1. A method of producing an object by selective laser sintering, comprising the steps of:
- dispensing a first layer of heat-fusible powder over a target surface having a width in a first direction;
defining a first scanning region of the target surface for a first cross-section of the object to be formed in the first layer of powder, said first scanning region having a width, in the first direction, substantially equal to the maximum width of the first cross-section in the first direction, and substantially smaller than the width of the target surface in the first direction;
scanning a directed energy beam in the first direction, beginning at a first end of said first scanning region and stopping upon reaching a second end of said first scanning region;
modulating the directed energy beam on and off during said scanning step so that the directed energy beam is turned on over selected portions of the first layer of powder corresponding to the first cross-section, to fuse the powder thereat; and
repeating said scanning and modulating steps in such a manner that adjacent scans of the directed energy beam overlap one another over the target surface.
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Abstract
A method and apparatus for fabricating three-dimensional objects according to the selective laser sintering process are disclosed. In order to reduce inconsistencies in structural and textural integrity, and in thermal effects that can cause distortion, methods for ensuring that overlapping laser scans are accomplished in a consistent manner relative to the thermal flow from the sintered locations are utilized. Methods are disclosed for achieving this by limiting the extent to which the laser scans object areas in the powder layers so that the time-to-return for adjacent overlapping scans is minimized; such minimization results in significantly less variation in the time-to-return overall.
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Citations
12 Claims
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1. A method of producing an object by selective laser sintering, comprising the steps of:
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dispensing a first layer of heat-fusible powder over a target surface having a width in a first direction; defining a first scanning region of the target surface for a first cross-section of the object to be formed in the first layer of powder, said first scanning region having a width, in the first direction, substantially equal to the maximum width of the first cross-section in the first direction, and substantially smaller than the width of the target surface in the first direction; scanning a directed energy beam in the first direction, beginning at a first end of said first scanning region and stopping upon reaching a second end of said first scanning region; modulating the directed energy beam on and off during said scanning step so that the directed energy beam is turned on over selected portions of the first layer of powder corresponding to the first cross-section, to fuse the powder thereat; and repeating said scanning and modulating steps in such a manner that adjacent scans of the directed energy beam overlap one another over the target surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus for fabricating a part, comprising the steps of:
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a target surface, having a width in a first direction; means for dispensing layers of a solidifiable material at said target surface; and means for scanning an energy beam across said solidifiable material at said target surface while modulating said energy beam on and off, said energy beam of sufficient energy to fuse said solidifiable material at said target surface when on, wherein said energy beam is turned on by said scanning means at locations corresponding to a cross-section of the part; wherein said scanning means is programmed to scan said energy beam beginning at a first end of a defined first scanning region of the target surface for the cross-section of the object to be formed and stopping at a second end of the first scanning region, said first scanning region having a width, in the first direction, substantially equal to the maximum width of a first area of the cross-section in the first direction, and substantially smaller than the width of the target surface in the first direction. - View Dependent Claims (11, 12)
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Specification