In-process detection and closed-loop control of the amplitude during ultrasonic vibration superimposed turning for predefined and highly efficient surface microstructuring

超声波振动叠加车削过程中振幅的过程检测和闭环控制，用于预定义和高效的表面微结构

• 批准号: 510749881
• 负责人: Professor Dr.-Ing. Welf-Guntram Drossel
• 金额: --
• 依托单位: Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik (IWU)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/510749881?language=en
• 关键词: process; detection; closed; loop; control

Increasing demands regarding the efficiency and functionality of technical systems put a stronger focus on their surface properties. Microstructured surfaces offer an especially high potential for improving these properties, for example a reduction of the sliding friction. Currently, microstructuring is usually realised by an additional process like laser ablation. This approach results in longer process chains and high costs. Consequently, a direct integration of the microstructuring into the final machining process is sought. Turning with an ultrasonic vibration superposition in the direction of the passive force represents a highly efficient process. Thereby, more than 20,000 microstructures per second can be generated directly in the final machining process. However, there are still open fundamental scientific questions regarding the generation of the microstructures under consideration of rapidly changing working angles on one hand and the automatic control of the system to ensure a constant vibration amplitude on the other hand.The objective of the research project is to gain an in-depth understanding of the integral interactions when turning with an ultrasonic vibration superposition in the direction of the passive force. The focus is set on controlling the ultrasonic vibration system as well as the mechanisms in the shear zone depending on the process parameters, materials and tools including the resulting surface microstructures. A close-to-process measuring of mechanical signals of the ultrasonic transducer instead of electrical signals is expected to enable a high precision closed-loop control of the amplitude of ultrasonic vibrations.For this task a special ultrasonic transducer with two interchangeable sonotrodes allowing for a precise adjustment of the vibration amplitude by the integrated sensors is designed. Data about the operating frequency, the current mode shape, and the present vibration amplitudes at the tool is collected by strain gauges, fiber Bragg gratings, and an accelerometer. Pilot experiments addressing the chip formation and kinematic simulations of the generated surface enable the setting of the necessary process parameters. For the experimental investigations, a bronze material is used. The data collected, the results from the geometrical analysis of the microstructured surface, and the chips generated are analysed. Based on this, differences between the manufactured surfaces and the simulated ones are linked to specific effect mechanisms and the data collected from the sensors. Furthermore, a closed-loop control including the signals of the sensors positioned near the cutting tool is developed. Consequently, the suitability of close-to-process sensors for the control of ultrasonic vibration systems can be evaluated.

对技术系统的效率和功能性的要求越来越高，对它们的表面性能更加关注。微结构化的表面提供了特别高的潜力来改善这些性能，例如减少滑动摩擦。目前，微结构化通常通过激光烧蚀等附加工艺实现。这种方法导致更长的工艺链和更高的成本。因此，寻求将微结构化直接集成到最终加工过程中。在被动力方向上叠加超声波振动进行车削是一种高效的工艺。因此，每秒可在最终加工过程中直接生成超过20，000个微结构。然而，在这方面，在快速变化的工作角度下产生微结构，另一方面，系统的自动控制以确保恒定的振动振幅，仍然存在着开放的基础科学问题。深入了解在被动力方向上与超声振动叠加时的整体相互作用。重点是控制超声振动系统以及剪切区的机制取决于工艺参数，材料和工具，包括所得的表面微观结构。为了实现超声波振动幅值的高精度闭环控制，设计了一种特殊的超声波换能器，该换能器具有两个可互换的超声波发生器，可通过集成传感器精确调节振动幅值。关于工作频率、当前模式形状和工具处的当前振动幅度的数据由应变计、光纤布拉格光栅和加速度计收集。解决芯片的形成和生成的表面的运动学模拟的试点实验，使必要的工艺参数的设置。对于实验研究，使用青铜材料。分析所收集的数据、来自微结构化表面的几何分析的结果以及所产生的芯片。在此基础上，制造表面和模拟表面之间的差异与特定的效应机制和从传感器收集的数据有关。此外，闭环控制，包括定位在切削刀具附近的传感器的信号被开发。因此，接近过程的传感器的超声波振动系统的控制的适用性可以进行评估。