Development Of Automatic Measurement System Of Departures From Flatness For Brake Backing Plate

The departures from flatness of brake backing plate is an important indicator of the quality of brake pad.However,most companies still use manual way of doing backing plate testing,measuring not only low efficiency and the measurement data is not reliable.This thesis provide technical support for enterprises to improve product quality and break the market monopoly by developing costs appropriately,data reliable and convenient automatic measurement system of departures from flatness.High-precision and high-efficiency measurement solution have been proposed to extract surface topography of backing plate by analyzing the existing electrical measurement solution.Calibrating the sensors and measuring plane by taking experiment.Separate structure,measuring structure and sorting structure was designed based on the measurement solution and PLC control.Principle and control methods of these structures are introduced in this thesis.Take into account the spatial distribution of data points,a new algorithm to construct 3D convex hull is proposed for the evaluation of departures from flatness based on the traditional method.Initial convex hull vertex can be obtained by reducing the dimension of the three-dimensional data.Reference Quickhull algorithm thinking to improve the speed of constructing the convex hull.Combined with the Means of classifying measured points to improve computational efficiency of departures from flatness.Host computer program of system was designed based on Qt development framework.Read and write the configuration file by calling QSettings class.Serial Port class was called to communicate with slave equipment as PLC and sensors.Curve and histogram is displayed by use of third-party graphics libraries(QWT).Measurement data can be storage,query and export by use of SQLite database.The measurement accuracy was estimated by analyzing the measurement error of single-point and calculation method.Repeatability and indication error with respect to CMM of measurement system is obtained by repeating experiment.All of these parameters proved the reliability of the system.