Image measurement of precision aluminum alloy forgings

A dimension measuring device for precision aluminium alloy forgings was developed based on digital image processing technology.In order to avoid image blurring caused by forging reflection,LED lighting on two sides of the forgings was used.Firstly,the captured images were preprocessed by 3×3 median filtering,fixed threshold and 8-neighborhood edge tracking to extract outer and inner boundaries of the forgings.Then the least square circle fitting algorithm was used to calculate dimension parameters.Experiments show that,compared to manual measuring,the maximum error of image measuring are 0.05mm for outer diameter,0.09mm for outer diameter,0.07mm for thickness difference,and 0.07mm for roundness error.The result show that image measuring method is feasible for precision forging measurement.