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Selective laser sintering: A definition of the process and an empirical sintering model.

机译：选择性激光烧结：工艺定义和经验烧结模型。

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Selective Laser Sintering{dollar}sp{lcub}rm TM{rcub}{dollar} (SLS) is a method of rapid prototyping three-dimensional objects from a computer image. The computer image is a CAD drawing or the result of a computer imaging process. The three-dimensional computer image is numerically sliced into thin layers, and the SLS machine then reproduces these slices, with a laser, by drawing the two-dimensional patterns onto thin layers of powder. Each new powder layer is placed above the previous one, building the three-dimensional object from the bottom up. The laser selectively adds heat to sinter the powder particles of that layer in a two-dimensional pattern, and to bond the surface layer to the underlying layer.; Determining the optimal set of operating parameters when forming a three-dimensional SLS object is important to produce objects which have uniform density and sharp surface features. This research includes the numerical modeling and predictive control of the SLS process. The sintering model is used to predict final part densities and ultimately to control the SLS machine.; Both finite-difference and finite-elements sintering models have been developed based on the conduction-diffusion equation. The model input includes SLS operating parameters, and the material specific information; such as thermal conductivity, specific heat, and sintering rate. The viscous sintering rate of amorphous polymer powders is measured in an isothermal experiment designed for this purpose. The model output includes void fraction and temperature profiles within a sintered layer as a function of time. Verification of the sintering model is done by comparing the sintering depths measured from samples made under varied conditions in the SLS machine, to those predicted by the model at the same conditions. Modeling of crystalline materials which involves the solution of a moving boundary problem is under current investigation.; The model can be used to optimize the SLS operating parameters for new amorphous materials after initial measurements of the material's sintering rate and solid thermal conductivity. The model also provides insight into a control strategy for the dynamic control of the laser power and scan speed to provide a more homogenous energy distribution when scanning a series of vectors that have variable lengths.
机译：选择性激光烧结{dollar} sp {lcub} rm TM {rcub} {dollar}（SLS）是一种从计算机图像中快速制作三维物体原型的方法。该计算机图像是CAD图或计算机成像过程的结果。将三维计算机图像从数值上切成薄层，然后SLS机器通过将二维图案绘制到粉末薄层上，用激光重现这些切片。每个新的粉末层都放置在前一层之上，从下至上构建三维对象。激光有选择地增加热量，以二维模式烧结该层的粉末颗粒，并使表面层与下面的层结合。在形成三维SLS对象时确定最佳的操作参数集对于生产具有均匀密度和锋利表面特征的对象很重要。这项研究包括SLS过程的数值建模和预测控制。烧结模型用于预测最终零件的密度并最终控制SLS机器。基于传导扩散方程，建立了有限差分和有限元烧结模型。模型输入包括SLS操作参数和材料特定信息；例如热导率，比热和烧结速率。在为此目的设计的等温实验中测量了非晶态聚合物粉末的粘性烧结速率。模型输出包括烧结层内的空隙率和温度分布随时间的变化。烧结模型的验证是通过将在SLS机器中在不同条件下制作的样品测量的烧结深度与模型在相同条件下预测的深度进行比较来完成的。目前正在研究涉及解决运动边界问题的晶体材料的建模。在初步测量材料的烧结速率和固体热导率之后，该模型可用于优化新非晶材料的SLS操作参数。该模型还提供了对激光功率和扫描速度的动态控制的控制策略的见解，以在扫描具有可变长度的一系列矢量时提供更均匀的能量分布。

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