Automatic Ultrasonic Detection and Measurement of Cracks in Cannon.

The end-on ultrasonic crack measurement technique has been refined and perfected to provide reliable automatic sensing and read out of the maximum crack depth and its location for each crack encountered as the probe moves in a helical path down the cannon tube. A mechanical scanning machine has been constructed and tested which inspects full length 105 millimeter cannon. An ultrasonic flaw detector senses, measures and continuously reads out the distance from the outside surface to the crack tip or bore surface. Digital logic circuits evaluate successive measurements and determine the maximum crack depth reading. This data is transferred to a data acquisition system.