The Measuring System For Hole Diameters And Center Distances Of Sheet Metals

Sheet metal workpieces are widely used in all kinds of products and the size precision of the holes on it directly affect the assembly quality and even working performance.To ensure the quality of sheet metal workpieces,it is very important to match the aperture and measure center distance of the small hole.The common measurement methods are all in contact type,such as measuring inner diameter with plug gauge,dial gauge,micrometer.However,these contact type measures are complicate to operate,high in failure rate,poor to monitor,can not meet the measurement requirements.With the development of digital image technology processing,use CCD to measure object’s geometry parameters has become the direction of modern precision measurement.This paper designs a kind of non contact measurement system for the aperture and center distance of the thin plate.The system uses the visual sensor,optical lens and the computer to collect picture of the measured parts without touching it.In the measurement system install high precision grating ruler on the movable arm,by moving the arm drive vision sensor move in the X and Y axes and collect pictures of small holes with different marking positions field of vision,and the move distance is determined by the grating position.The visual sensor calculate the hole diameter and the center coordinates according to the picture,and then sent the result to the computer.After that computer calculate the center distance on the basis of center coordinates.This Measurement system apply software compensation to eliminate system error and through SPC programs to monitor the production process and at last control its quality.