Part Generation by Layerwise Selective Sintering

该提案将研究一种新的制造工艺，该工艺通过激光有选择地烧结每一层粉末来分层构建零件。该过程的目标是直接从CAD数据库自动生成一般形状的三维零件，而无需零件专用工具或人工干预。建立的每一层都对应于零件的横截面。粉末被沉积在一个薄层的盒子里；在每一层沉积之后，粉末的表面用高功率激光束进行光栅扫描。调制激光束的强度，使粉末在该特定横截面上被零件占据的区域烧结或熔化。在那些没有烧结的地方，粉末仍然是松散的。然后沉积另一层粉末并进行光栅扫描。这一过程不断重复，直到生产出整个零件。将使用的方法是结合计算机建模和分析的实验/经验方法。本研究的目的是建立一个工艺模型，制定粉末和工艺参数的选择规则，并探索后处理。前期工作已用塑料粉进行；所提出的工作需要证明在普通工程材料上的可行性。提出的过程，通过光栅扫描和从CAD数据库中选择烧结的组合产生三维零件，而没有零件特定的工具或人为干预，似乎是新颖的。这一过程将有助于快速生产原型零件，从而减少产品开发时间。

This proposal will investigate a new manufacturing process which builds up parts in layers from a powder by selectively sintering each layer with a laser. The objective of the process is to automatically produce three-dimensional parts of general shape directly from a CAD database without part-specific tooling or human intervention. Each layer that is built up corresponds to a cross-section of the part. Powder is deposited into a box in thin layers; after each layer is deposited, the surface of the powder is raster-scanned with a high-power laser beam. The intensity of the laser beam is modulated so that the powder is sintered or fused in the areas that are to be occupied by the part at that particular cross-section. In those areas not sintered, the powder remains loose. Another layer of powder is then deposited and raster-scanned. The process is repeated until the entire part is produced. The methodology to be used is an experimental/empirical approach used in conjunction with computer modeling and analysis. The objectives of the proposed research are to formulate a process model and rules for selection of powders and process parameters, and to explore post-treatments. Preliminary work has been conducted with plastic powder; the proposed work is needed to demonstrate feasibility with common engineering materials. The proposed process which produces a three-dimensional part by the combination of a raster scan and selective sintering from a CAD database without part specific tooling or human intervention appears to be novel. This process should facilitate the quick production of prototype parts which should reduce product development time.