Large diameter pipes of prestressed concrete with a length of 10–20 ft. used for water transport are made in rotating moulds. To control the thickness of these concrete pipes during production, an ultrasonic pulse-echo system mounted at the end of the feeder is used. Basically, the air gap between feeder and inner pipe wall is continuously measured, whereby deviations due to misalignment of the feeder are electronically compensated. A prototype version of the system has proved its usefulness. An accuracy of ±5% of the nominal wall thickness was obtained.
A newly developed digital scanning electron microscope, the JSM-6300, has the following features: Equipped with a narrower conical objective lens (OL), it allows high resolution images to be obtained easily at a short working distance (WD) and a large specimen tilt angle. In addition, it is provided with automatic functions and digital image processing functions for ease of operation.Conical C-F lens: The newly developed conical C-F objective lens, having low aberration characteristics over a wide WD range, allows a large-diameter (3-inch) specimen to be tilted up to 60° at short WD, and provides images with low magnifications starting at 10*. On the bottom of the lens, a p n junction type detector is provided to detect backscattered electrons (BE) from the specimen. As the narrower conical 0L increases the secondary electron (SE) detector's field intensity on the specimen surface, high SE image quality is obtained.
Monitoring of temperature variation in manufacturing process of centrifugally cast pipe using infrared thermography