| 摘要 |
PURPOSE:To allow automatic decision of internal defect with high accuracy by processing the data of impact sound produced by knocking a concrete product at many points and setting a decision criterion for each product. CONSTITUTION:An ALC(Aerated Lightweight Concrete) product transferred on a conveyor 1 is knocked vertically by means of a hammer unit 4 provided, at the head of an air cylinder, with a hammer head 3 in order to knock the concrete product with constant force. A sound level meter 5 collects the sound and produces a sound pressure. An A/D converter 6 converts an analog AC voltage signal, corresponding to the sound pressure, into a digital signal which is fed to a personal computor 7. The personal computor 7 calculates the peak value of sound pressure at each knocking point, the sound level at nondefective part, the reference sound level, etc. Internal defect is then decided with reference to the reference sound level and the inspection results are displayed on a screen. |
