The Study On The Machine Vision Method Of Screw Measurement

The screw connection structure has been widely used in mechanical equipments and other devices because of its high reliability, convenient assembly and disassembly characters. The compatibility and reliability of the screw are requested strictly, so it needs to be measured seriously. Mechanical measurement is mainly used in china now, but it is mainly carried out manually and can't satisfy the demand of production because of its low measuring speed and low precision. Machine vision is a new technology advanced along with the development of computer technology, its advantages and screw geometric parameters measurement are combined in this study in order to investigate the machine vision of screw measuring and attain high speed and precision.Because of the complicated shape outline and numerous parameters of the screw work pieces, the big screw diameter, screw angle and screw pitch parameters are chosen to be measuring objects of machine vision. The corresponding measurement steps and image processing algorithm are designed and applied aiming at different characteristics of each parameter, Visual C++ and Matlab programs are provided too. The characters of target and noise in screw image are analyzed using histogram equalization, nonlinear transform and hybrid filter. Mass center algorithm, hough transform algorithm and screw pitch calculation method are applied to measure the geometry parameters. Screw bottle is chosen to be a sample to carry out measuring experiment and ideal result is achieved. The error source and factors of the system are eliminated as far as possible through analysis and research. The machine vision technology can be applied to carry out online measuring with high measurement speed and precision, so it will be the development direction of the screw measurement in the future.The research of this study can be used to develop online auto measuring machine and numerical screw producing machine, the proposed non-contact measurement technology based on the machine vision has wide meanings and also has important reference value for studying the auto precision measurement instruments and online measuring technology in manufacturing.