Patent ID: 6443011
Filing Date: 2002-09-03
Classification: G01N

Abstract:
A device for detecting faults in and/or measuring the wall thickness of a continuously moving plastic body by means of ultrasonic signals, said device comprising:a plurality of measuring heads (A, B, C, D) from which said ultrasonic signals are perpendicularly introduced into said plastic body by means of an ultrasonic transmitter, said measuring heads being distributed one beside the other adjacent to said plastic body and transversely to the direction of motion of said plastic body, and said measuring heads including at least one receiving surface thereon comprising a plurality of measuring zones; said plastic body having a convexly curved surface, where said surface contains overlapping, predetermined surface zones; said measuring heads (A, B, C, D) being disposed relative to said plastic body to allow for the sonic propagation, scatter and refraction of said ultrasonic signals on said convexly curved surface of said plastic body, where reflected signals of said ultrasonic signals emitted by one of said measuring heads (B) are received by said emitting measuring head (B) and by said measuring heads (A, C) adjacent on both sides of said emitting measuring head (B); said signals emitted from said measuring heads (A, C) adjacent on both sides of said measuring head (B) being received by said measuring head (B) from reflected signals emanating from said predetermined surface zones associated with said measuring heads (A, B, C); said reflected signals being received by said measuring heads and supplied to an evaluation unit; wherein the number of said adjacent measuring heads (A, C) is N&GreaterEqual;Ï€&it;â€ƒ&it;RS&it;â€ƒ&it;tan&it;â€ƒ&it;Î±,the diameter of said at least one receiving surface of each measuring head is K&GreaterEqual;2&it;â€ƒ&it;Ï€&it;â€ƒ&it;RNT,and the wavelength of said ultrasonic signals is Î»&GreaterEqual;R&it;â€ƒ&it;(1-cos&it;360NT),â€ƒwherein N=number of measuring heads; R=external radius of curvature of said convexly curved surface of said plastic body; S=distance of said measuring heads from said convexly curved surface of said plastic body; &agr;=opening angle of said ultrasonic transmitter of said measuring heads; K=diameter of said at least one receiving surface of each of said measuring heads; T=number of measuring zones per measuring head; and &lgr;=wavelength of said ultrasonic signal.