基于PVDF压电薄膜的高频切削力信号传感器研制

发布时间：2018-09-06 07:58

【摘要】：切削力是机械加工中的主要参数,测力仪直接测量是应用广泛且使用方便的切削力获得方法。将压电材料作为传感元件可提高测力仪性能,PVDF(Polyvinylidene Fluoride)压电薄膜因其动态特性好、频响范围宽、灵敏度高、柔性大、成本低等优点愈加广泛地被应用在切削力动态监测中。本文以高速微铣削中动态切削力测量为研究对象,利用PVDF压电薄膜设计一款高性能、低成本的新型压电测力传感器。首先,根据并联式应变集中结构设计加工简化的一维传感器,并做常规转速铣削试验验证结构合理性。根据弹性系统振动力学推导出测力平台自由振动时固有频率与各参数关系,选定测力平台尺寸范围。利用四周高刚度弹性体并联中间低刚度弹性薄片结构和截面突变结构分别设计测力平台对切削分力Fx和Fy与Fz的敏感元件。利用有限元软件对测力平台做模态分析与静力学分析,得到测力平台测量范围。然后,根据使用条件和PVDF压电薄膜性能确定压电方程,制备薄膜传感器和压电测力平台。利用有限元软件对压电测力平台做机械-压电联合仿真,得到各向输出电场与施加载荷关系。根据PVDF压电薄膜极化方向性质和各向载荷-电荷关系推出测力平台解耦算法,得到仿真与理论两种解耦式。最后,利用DASYLab(Data Acquisition system Laboratory)多功能组态软件设计上位机部分。搭建测试系统,选择不同每齿进给量进行铣削试验,得到切削力与每齿进给量关系。选择合适参数,进行测力平台与Kistler测力仪对比试验,并将得到的切削力信号做解耦处理,试验证明测力传感器能较好地反映铣削时切削力动态变化,且解耦矩阵能一定程度上降低各向干扰,提高监测系统测量精度。
[Abstract]:Cutting force is the main parameter in machining. The direct measurement of force meter is a widely used and convenient method to obtain cutting force. Using piezoelectric material as sensing element can improve the performance of dynamometer. PVDF (Polyvinylidene Fluoride) piezoelectric film has been widely used in dynamic monitoring of cutting force because of its good dynamic characteristics, wide frequency response range, high sensitivity, large flexibility, low cost and so on. In this paper, a new piezoelectric force sensor with high performance and low cost is designed by using PVDF piezoelectric thin film as the research object of dynamic cutting force measurement in high speed micro-milling. Firstly, the simplified one-dimensional sensor is designed and manufactured according to the parallel strain concentrated structure, and the rationality of the structure is verified by the conventional rotational speed milling test. According to the vibration dynamics of the elastic system, the relationship between the natural frequency and the parameters in the free vibration of the force-measuring platform is derived, and the size range of the force-measuring platform is selected. The sensing elements of the force-measuring platform for cutting Fx, Fy and Fz are designed by using the structure of the elastic plate with high stiffness and the structure of the elastic plate with low stiffness in parallel and the abrupt structure of the section. The finite element software is used to do modal analysis and static analysis on the force-measuring platform, and the measuring range of the force-measuring platform is obtained. Then, the piezoelectric equation is determined according to the operating conditions and the performance of PVDF piezoelectric film, and the thin film sensor and piezoelectric force measuring platform are prepared. The finite element software is used to simulate the piezoelectric force-measuring platform, and the relationship between the output electric field and the applied load is obtained. According to the polarization direction properties of PVDF piezoelectric film and the load-charge relation in each direction, the decoupling algorithm of the force-measuring platform is derived, and two decoupling formulas are obtained. Finally, the part of upper computer is designed by using DASYLab (Data Acquisition system Laboratory) multi-function configuration software. The test system was set up and the milling test was carried out with different feed rate of each tooth, and the relation between cutting force and feed rate per tooth was obtained. Choosing suitable parameters, comparing the force measuring platform with the Kistler dynamometer, and decoupling the cutting force signal, it is proved that the force sensor can well reflect the dynamic change of cutting force in milling. The decoupling matrix can reduce the interference of each direction to some extent and improve the measuring accuracy of the monitoring system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212

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