Novel Powder Metallurgy Compacts with Internal Structures

先前开发了一种新的制造技术，并申请了实用新型专利，该技术能够在两个步骤中生产完全封闭在金属中的中空部件。该技术利用粉末冶金压制和烧结技术将金属粉末致密成完全包裹内部结构的固体。这些内部结构最常见的是由含有石蜡核心的金属外壳组成。首先，金属粉末被压紧(压实)在包含软蜡填充的芯的固体金属外壳周围，以形成包含内部结构的金属压坯或部件。在特定条件下对压坯进行随后的加热(“烧结”)允许石蜡从压坯中熔化，从而产生中空的金属部件。目前，壳体、壳体和芯体的应力状态尚不清楚，壳体机械故障通常是由于压实压力过高造成的。为了解决这一问题，将开发一个有限元模型，模拟金属石蜡芯内部结构的压实过程。该模型将采用金属粉末和蜡芯的非线性材料模型，以实现对粉末致密化的准确预测。然后将模型结果与内部结构压实的实验密度图进行比较。一旦得到验证，该模型将成为一个有价值的设计工具，因为它能够预测壳体和核心材料中的应力。进一步的工作将集中在对内部结构如何破坏金属粉末的常规压实的基本理解上。通过获得这一基本水平的理解，将加快将该技术开发成商业就绪产品的进展。

A novel manufacturing technology was previously developed, with a utility patent applied for, which is capable of producing a hollow component in only two steps that is completely enclosed in metal. The technology leverages the powder metallurgy press-and-sinter technique to densify metal powder into a solid body completely encapsulating an internal structure. These internal structures most often are composed of a metallic shell containing a paraffin wax core. Firstly, metal powder is pressed ("compacted") around a solid metal shell containing a soft wax-filled core to form a metal compact or part containing an internal structure. Subsequent heating ("sintering") of the compact at particular conditions allows for the paraffin to melt out of the compact, thus producing a hollow metal part.******Currently, the stress state of the body, shell, and core is unknown and shell mechanical failures often result from overly high compaction pressures. To address this, a finite element model will be developed which simulates the compaction of a metal, paraffin-core internal structure. The model will employ nonlinear material models for both the metal powder and wax core to allow for an accurate prediction of the powder densification. The model results will then compared against experimental density maps of internal structure compacts. Once validated, this model will become a valuable design tool as it is capable of predicting the stress in both the shell and core materials. Further work will focus on the fundamental understanding of how the internal structure disrupts the conventional compaction of the metal powder. By gaining this fundamental level of understanding, progress towards developing the technology into a commercial-ready product will be accelerated.**