Powder spreader
Powder spreaders suitable for use with layered manufacturing processes are disclosed in which a strip of flexible material of a width which spans the powder bed is used to spread, level, and, optionally, compact deposited powder to form a layer of the powder bed. The strip surface moves relative to the deposited powder it is spreading as the working portion of the strip, i.e., the portion of the strip that is in contact with the powder, traverses across the powder bed so that it can provide lift to the powder in front of it and, optionally, compaction to the powder below it. The working portion of the strip can be configured to have its leading and trailing surface contours to be different from one another, and, optionally, to have these contours and its bottom edge contour be independently adjustable. Layered manufacturing systems comprising such powder spreaders are also disclosed.
1. A powder spreader comprising:
a) a flexible strip;
b) a motor-driven first roll;
c) a transportable nose guide;
wherein as the nose guide is adapted to be transported longitudinally across a support surface behind a pile of deposited powder the first roll causes the strip to move over the nose guide to provide lift to the powder of the pile and to distribute the pile of powder in the form of a powder layer upon the support surface; and
d) stiffening element includes a plurality of adjustable supports, at least one of the supports of the plurality of supports being independently adjustable to control the contour of the nose guide.
2. The powder spreader of claim 1 , wherein said stiffening element for providing vertical and lateral support to the nose guide.
3. The powder spreader of claim 2 , wherein at least one of the first roll and the nose guide are selectively movable so as to control the tension of the strip between the roll and the nose guide.
4. The powder spreader of claim 1 , further comprising a tension device for controlling the tension and shape of the strip.
5. The powder spreader of claim 4 , wherein the tension device has a first end for contacting a surface of the strip, wherein the position of the first end is selectable to control a lead angle formed between the strip and the support surface or a trailing angle formed between the strip and the surface of the powder layer.
6. The powder spreader of claim 1 , wherein the strip is in the form of an endless loop.
7. The powder spreader of claim 1 , further comprising a transport device adapted to move the nose guide longitudinally across the support surface.
8. The powder spreader of claim 1 , further comprising a second roll, the first and second rolls being configured to cooperate as a pair of supply and take up reels for the strip and to move the strip over the nose guide.
9. The powder spreader of claim 8 , wherein said stiffening element for providing vertical and lateral support to the nose guide.
10. The powder spreader of claim 8 , further comprising a tension device for controlling the tension and shape of the strip.
11. The powder spreader of claim 10 , wherein the tension device has a first end for contacting a surface of the strip, wherein the position of the first end is selectable to control a lead angle formed between the strip and the support surface or a trailing angle formed between the strip and the surface of the powder layer.
12. The powder spreader of claim 8 , further comprising a transport device adapted to move the nose guide longitudinally across the support surface.
13. The powder spreader of claim 1 , wherein the strip comprises a material selected from the group consisting of rubber, polytetraflouroethylene, polystyrene, and polyethylene.
14. A layered manufacturing system comprising:
a) a process controller;
b) a powder delivery system;
c) a printer;
d) a support surface; and
e) a powder spreader having
i) a flexible strip;
ii) a motor-driven first roll;
iii) a transportable nose guide; wherein as the nose guide is adapted to be transported longitudinally across a support surface behind a pile of deposited powder the first roll causes the strip to move over the nose guide to provide lift to the powder of the pile and to distribute the pile of powder in the form of a powder layer upon the support surface; and
iv) stiffening element includes a plurality of adjustable supports, at least one of the supports of the plurality of supports being independently adjustable to control the contour of the nose guide;
wherein the process controller is operably connected to the powder delivery system, the printer, the support surface, and the powder spreader to control the layered manufacturing system to form a three dimensional article.
15. The layered manufacturing system of claim 14 , wherein the layered manufacturing system is a three-dimensional printing system.
16. The layered manufacturing system of claim 14 , wherein the layered manufacturing system is a selective laser sintering system.
17. The layered manufacturing system of claim 14 , wherein said stiffening element for providing vertical and lateral support to the nose guide.
18. The layered manufacturing system of claim 14 , wherein the powder spreader further comprises a tension device for controlling the tension and shape of the strip.
19. The layered manufacturing system of claim 18 , wherein the tension device has a first end for contacting a surface of the strip, wherein the position of the first end is selectable to control a lead angle formed between the strip and the support surface or a trailing angle formed between the strip and the surface of the powder layer.
20. The layered manufacturing system of claim 14 , wherein the strip is in the form of an endless loop.
21. The layered manufacturing system of claim 14 , wherein the powder spreader further comprises a second roll, the first and second rolls being configured to cooperate as a pair of supply and take up reels for the strip and to move the strip over the nose guide.
22. The layered manufacturing system of claim 21 , wherein said stiffening element for providing vertical and lateral support to the nose guide.
23. The layered manufacturing system of claim 14 , wherein the strip comprises a material selected from the group consisting of rubber, polytetraflouroethylene, polystyrene, and polyethylene.