Thermal effects when turning Al-MMC - experiments and simulations

车削 Al-MMC 时的热效应 - 实验和模拟

• 批准号: 260779103
• 负责人: Professor Dr.-Ing. Jan C. Aurich
• 金额: --
• 依托单位: Lehrstuhl für Fertigungstechnik und Betriebsorganisation (FBK)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/260779103?language=en
• 关键词: Thermal; effects; when; turning; Al

Aluminum-Metal-Matrix-Composites (Al-MMC) are two-phase high-performance materials. Hence, an increasing usage is predicted for these materials due to their excellent properties. The generated heat during turning causes thermal expansions of the workpiece and the tool, which decrease the accuracy of machining. In order to determine and compensate such deformations, time and cost-intensive experimental investigations need to be carried out at present. Since Al-MMC are high cost materials, it is of particular interest to reduce the experimental effort for this class of materials. In the first and second period of the project, finite element models to calculate the deformations of the workpiece and the tool when turning aluminum and Al-MMC were developed. In the third period of the project thermal effects during turning complex workpiece geometries will be compensated. The heterogeneous meso-scale of the Al-MMC has been represented in a material model in order to determine the required material properties for a local model of chip formation and a global model of the workpiece. The heat flux into the workpiece and the tool respectively as well as the process forces are calculated using the local model of chip formation. These results serve as boundary conditions for the global model of the workpiece and the tool. The global models calculate the respective temperature distribution, the associated thermal expansion and the deformation due to the process forces. The developed finite element models will be used in the third period of the project to determine strategies for the compensation of thermal effects in turning of complex workpiece geometries. Afterwards, these strategies are to be verified experimentally. A first general reduction of thermal effects on the accuracy of machining is performed by determining process parameters and sequences of individual operations that reduce the thermal loads on the workpiece and the tool. The accuracy of machining is thus remarkably enhanced. The remaining deviation from the nominal workpiece geometry, caused by thermal effects in the workpiece and the tool, can then be compensated through accordingly adapted depths of cut. To ensure both a minimized deviation from the nominal diameter and an appropriate surface integrity, rough turning and finish turning will be considered. The tool paths, which are the result of the adapted depths of cut, for the experimental investigations are generated using CAD-CAM technology. Potential differences in terms of the calculated and experimentally measured accuracy of machining will be analyzed by multiple experimental results, such as the temperature distribution and the process forces. As a result of the project, for the first time experimentally validated finite element models allowing for process planning when turning aluminum and Al-MMC will be available. The accuracy of machining can thus be remarkably enhanced.

铝 - 金质 - 复合材料（AL-MMC）是两相高性能材料。因此，由于这些材料的出色特性，预测这些材料的使用将增加。转弯期间产生的热量会导致工件和工具的热膨胀，从而降低了加工的准确性。为了确定和补偿此类变形，目前需要进行时间和成本密集的实验研究。由于Al-MMC是高成本材料，因此减少此类材料的实验努力特别有趣。在项目的第一个和第二个时期，开发了有限元模型来计算工件的变形和转动铝和Al-MMC时的工具。在转动复杂工件的第三阶段，将补偿复杂工件几何形状的热量效应。 Al-MMC的异质性中尺度已在材料模型中表示，以确定芯片形成的局部模型所需的材料特性和工件的全局模型。使用芯片形成的局部模型计算了进入工件和工具以及工艺力的热通量。这些结果是工件和工具的全局模型的边界条件。全局模型计算各自的温度分布，相关的热膨胀和由于过程力引起的变形。开发的有限元模型将在项目的第三阶段使用，以确定复杂工件几何形状转向热量效应的策略。之后，这些策略将得到实验验证。通过确定减少工件和工具上热载荷的单个操作的过程参数和序列来执行对加工精度的热效应对加工精度进行的首次总体降低。因此，加工的准确性得到了显着提高。然后，可以通过相应地适应切割深度来补偿由工件和工具中的热效应引起的名义工件几何形状的剩余偏差。为了确保最小化名义直径的偏差和适当的表面完整性，将考虑粗糙的转弯和表面转弯。使用CAD-CAM技术生成实验研究的剪切深度的结果，这是剪切深度的结果。在计算和实验测量的加工精度方面的潜在差异将通过多个实验结果（例如温度分布和过程力）分析。该项目的结果是，首次经过实验验证的有限元模型，允许在转动铝和Al-MMC时进行过程计划。因此，加工的准确性可以显着增强。