Dynamics of machining

机械加工是制造机械零件中使用最广泛的操作。昂贵的航空航天零件是从固体块通过去除90%的材料加工而成的。 汽车工业中大规模生产线的原型成本可能达到数百万美元，以缩短加工时间，同时避免废品率。该行业需要高生产率的加工策略，通过在昂贵的物理试验之前预测制造步骤的物理性能来保持竞争力。这项研究将有助于机床主轴，控制系统和加工操作的数学建模。数学模型将用于预测设计和制造方案的结果，这将使工程师能够优化制造过程。 本研究的重点是线镗操作模型，机床主轴，和计算机控制器的虚拟仿真加工操作。所有轴承座，如曲柄、凸轮和涡轮机轴的轴承座，都是用带有多个镶块的细长杆钻孔的。如果杆件没有得到很好的支撑，并且选择了不正确的速度、切削深度和进给，则系统会经历严重的颤振，从而导致公差违规和表面光洁度质量差。类似地，如果主轴没有以对称刚度组装，则机器不能以生产速度使用。本研究将发展一种直线镗削设计与分析模型，用以预测长孔镗削的切削力、扭矩、功率、动态响应及无颤振切削条件。目前的知识将进一步扩展，以评估他们的生产率在高速加工的模具，模具和航空航天零件的非对称主轴动力学的惩罚。机床的计算机数控（CNC）也将在虚拟环境中建模，这将允许制造工程师在进行昂贵的试验之前选择最佳的CNC参数和加工策略。该研究将丰富现有的加工知识，实现一个全面的，科学的和物理的虚拟加工技术。

Machining is the most widely used operation in manufacturing mechanical parts. Costly aerospace parts are machined from solid blocks by removing 90% of the material. Prototyping costs of mass production lines in the automotive industry can reach a few million dollars in order to shorten the machining time while avoiding scrap rates. The industry needs productive machining strategies to stay competitive by predicting the physical performance of manufacturing steps ahead of costly physical trials. This research will contribute to the mathematical modeling of machine tool spindles, control systems, and machining operations. The mathematical models will be used to predict the outcome of the design and manufacturing scenarios, which will enable the engineer to optimize the manufacturing processes. The focus of this research is to model line boring operations, machine tool spindles, and computer controllers for virtual simulation of machining operations. All bearing housings, such as housings for crank, cam, and turbine shafts, are bored using slender bars carrying multiple inserts. If the bar is not well supported and the incorrect speed, the depth of cut and feed are selected, the system experiences severe chatter vibrations leading to tolerance violations and poor surface finish quality. Similarly, if the spindle is not assembled with symmetric stiffness, the machine cannot be used at productive speeds. This research will develop a line-boring design and analysis model which will predict the cutting forces, torque, power, dynamic response, and chatter free cutting conditions of boring long bores. The current knowledge will be further extended to assess the penalty of non-symmetric spindle dynamics on their productivity during the high speed machining of dies, molds, and aerospace parts. The Computer Numerical Control (CNC) of the machine tool will also be modeled in virtual environment, which will allow the manufacturing engineers to select the most optimal CNC parameters and machining strategies before conducting costly trials. The proposed research will enrich the current knowledge in machining to achieve a full, science and physics based virtual machining technology.