Method and apparatus for inspecting communicating hole of a cast molded article

摘要

A transmitter of audible sound waves is disposed at one end of a communicating hole of a cast molded article such as a cylinder block, and a receiver of audible sound waves is disposed at the other end of the communicating hole. The quality of the communicating hole is determined by receiving audible sound waves from a transmitter which have passed through the communicating hole and computing and processing a frequency spectrum of the received audible sound waves based on a reference frequency spectrum.