Minimizing Tolerance Loss in the Solid Freeform Fabrication of Next Generation Tooling

实体自由形状制造(SFF)方法允许直接从计算机辅助设计模型以分层的方式自动构建任意复杂的形状。在工具制造的SFF技术的发展中，制造具有高水平几何精度的零件是很重要的。这项研究的重点是预测、测量和最小化基于热沉积的SFF工艺生产的零件的公差损失。对于热沉积，SFF中的公差损失是由残余应力引起的，其形式是大规模的零件翘曲或尺寸变化。预测和控制公差损失的能力对于制造具有相互连接的部件的复杂组件至关重要，例如注塑模具。为了测量和预测简单几何形状和完全复杂的三维零件的公差损失，提出了实验和固体力学分析。结果将通过生产复杂形状、多材料的注塑模具来展示。这项研究对于理解控制部分公差损失的基本问题具有重要意义。这可能会导致有用的数学模型来预测零件公差损失作为零件几何的函数。基于模型的测试结果可以很好地指示保持零件公差的最佳方法。这项研究本质上是跨学科的，它与行业有很强的联系。

Solid freeform fabrication (SFF) methodologies allow arbitrarily complex shapes to be automatically built in a layered fashion directly from Computer Aided Design models. In the development of SFF techniques for tooling manufacture, the creation of parts with a high level of geometric accuracy is important. This research focuses on predicting, measuring, and minimizing tolerance loss in parts produced by thermal deposition based SFF processes. With thermal deposition, tolerance losses in SFF are caused by residual stress, taking the form of large-scale part warping or dimensional changes. The ability to predict and control tolerance loss is critical for manufacturing intricate assemblies with interconnecting parts such as injection mold tooling. Experiments and solid mechanics analyses are proposed to measure and predict tolerance loss in simple geometries and for fully complex three-dimensional parts. Results will be demonstrated by producing complex shaped, multi-material injection mold tooling. This research is central to the understanding of the fundamental issues which control part tolerance loss. It may lead to useful mathematical models for predicting part tolerance loss as a function of part geometry. The model-based test results could provide a good indication of the best means for maintaining part tolerance. The research is interdisciplinary in nature and it has a strong tie with industry.