Near process flow measurements of the cooling lubricant supply in grinding processes

两相流中的光流测量特别具有挑战性，因为通常未知的、波动的折射率场引起的光的折射会导致未知的测量偏差。这尤其适用于磨削过程中的冷却润滑剂（CL）供应。由于流场测量对于冷却机制的基本理解以及磨削工艺的设计是必不可少的，因此该项目的目的是首次验证粒子图像测速仪（PIV）用于冷却剂流场的调查，并使用它来澄清冷却剂流动行为和冷却性能之间的相关性。对于磨削过程中的近过程PIV测量，基于光纤实验方法进行了深入的测量不确定性分析，以量化折射率变化的影响。的折射率场的变化对确定的粒子的位置，以及光片的偏转的效果测量与空间和时间分辨率。通过时间平均和基于模型的校正，减小了流速场的测量误差。此外，它是要检查平均折射率场是否可以被建模的基础上的平均冷却剂射流的几何形状，它可以被用来通过几何光学估计系统偏差的粒子位置。需要对砂轮附近的流量进行测量，以确定与冷却相关的CL流量特性。为此，使用边界层优化的PIV评估，并表征光片在砂轮表面上的直接反射的干扰影响，包括由此产生的间接流动照明。对于选定的工作点，所产生的流场的CL供应测量PIV没有工具-工件接触和单独的相应的冷却性能测量的磨削模拟试验台的装置。其目的是研究冷却性能和独立于工件的研究CL流之间的联系，而斜坡磨削试验用于检查结果是否可以直接转移到金属部件的加工过程中。为了加强对复杂CL流动现象的研究，分析了立体和时间分辨PIV测量的测量不确定度，并实施了传感砂轮和三分量测力计，以调查CL流动对磨削过程中热机械载荷集体的影响。

Optical flow measurement in two-phase flows is particularly challenging because refraction of light due to the usually unknown, fluctuating refractive index field can lead to unknown measurement deviations. This applies in particular to the cooling lubricant (CL) supply during grinding. Since flow field measurements are indispensable for a fundamental understanding of the cooling mechanism and thus for a design of the grinding process, the aim of the project is to validate particle image velocimetry (PIV) for the first time for the investigation of coolant flow fields and to use it to clarify the correlation between the coolant flow behavior and the cooling performance. For near-process PIV measurements during grinding, an in-depth measurement uncertainty analysis is carried out based on a fiber-optical, experimental approach in order to quantify the influence of refractive index variations. The effect of the refractive index field variations on the determination of the particle position as well as the deflection of the light sheet is measured with spatial and time resolution. The resulting measurement error of the flow velocity fields is reduced by means of temporal averaging and model-based correction. In addition, it is to be examined whether an average refractive index field can be modeled on the basis of the mean coolant jet geometry, which can be used by means of geometric optics to estimate systematic deviations of the particle position. Flow measurements near the grinding wheel are required to identify CL flow characteristics relevant for cooling. For this purpose, a boundary layer-optimized PIV evaluation is used and the disturbing influence of direct reflections of the light sheet on the grinding wheel surface is characterized, including the resulting indirect flow illumination. For selected operating points the resulting flow fields of the CL supply is measured by PIV without tool-workpiece contact and separately the corresponding cooling performance is measured by means of a grinding-analogy test rig. The aim is to investigate the connection between the cooling performance and the investigated CL flow that is independent from the workpiece, whereas ramp grinding tests are used to check whether the results can be directly transferred to the machining process of metallic components. For the enhanced study of complex CL flow phenomena, the measurement uncertainty of stereoscopic and time-resolved PIV measurements is analyzed, and a sensory grinding wheel and a 3-component dynamometer are implemented to investigate the effect of the CL flow on to the thermomechanical load collective during grinding.