Detection Method for Shrinkage Cavities Inside Spheroidal Graphite Cast Iron Using Vibration Measurement by Electromagnetic Force Excitation

Abstract

The inspection of shrinkage cavities formed inside spheroidal graphite cast iron during the manufacturing process of spheroidal graphite cast products, including large cast structures and machine parts, is considered to be important for quality assurance of cast products. X-ray and ultrasonic methods are generally used for this inspection. However, the former inspection method takes a long time and considerable equipment costs, the latter method requires the use of water as a contact couplant and to polish the surface of the inspection site of the cast iron. In an actual manufacturing factory, there is a demand for a simple and quick method for inspecting shrinkage cavities inside cast iron. In this research, as a simple and high-speed inspection method to evaluate shrinkage cavities inside cast iron by measuring of the vibration of the electromagnetic force is proposed. Three-dimensional electromagnetic field analysis using the finite element method and displacement analysis was performed to analyze the phenomenon, and the usefulness of this method was confirmed by verification experiments.