Method and device for measuring ovality of nodular cast iron pipe

The invention discloses a method and device for measuring ovality of a nodular cast iron pipe, and the method comprises the steps: installing a visual camera on a gripper of a mechanical arm, and installing five eddy current sensors on a circular ring which takes the visual camera as a circle center, so that the five sensors are distributed on the circular ring; and then the circle of the distributed sensor is moved to coincide with the ellipse center of the nodular cast iron pipe through the mechanical arm, so that a coordinate system is established subsequently for ellipse fitting. The distance between the electric vortex sensor and the surface of the nodular cast iron pipe is calibrated through the skin effect, position coordinates of the five points can be obtained, then an elliptic equation of the nodular cast iron pipe is fitted according to the principle that a unique ellipse can be determined according to the five points (any three points are not collinear), and the ovality of the ellipse is calculate