Researching On An Automatic Instrument For Measuring Screw Parameters

This paper introduces an instrument for auto-measuring parameters of outside screw. The instrument obtains 2-D data of the screw axis profile section by linear matrix CCD through with optical projection and machine driving, and then works out its parameters. The measuring system researched on is combined with optics, mechanics and electronics.This paper includes: principle of the instrument, the application of CCD, high-speed data sampling and storage, serial communication, edge detection of screw image and calculate method of screw parameters. The paper presents a way associated linear matrix CCD with stepper motor to realize high precision measurement. A new way of data sampling is developed in hardware that achieves high-speed data sampling storage without the limitation of CPU speed. The problem of the interface and serial communication between microcontroler and PC is solved by API function in Visual C++. In oftware, the grads operator is used to detect the edge of screw image, and least squares procedure is employed to fit the external screw profile line, finally, geometrical parameters of screw are worked out.