Patent GB-815243-A (GB)
Title: Gauging elongated bodies
IPC: B29C48/90
Filed: 1956-07-02
Abstract: 815,243. Pneumatic gauging. CORNING GLASS WORKS. July 2, 1956 [July 6, 1955], No. 20416/56. Class 106 (2) A method of gauging an elongated body comprises employing the body to restrict the volume of air flow from a confined surrounding space 14 to atmosphere at a predetermined rate for a given cross-section of the body, issuing air from a second confined space B at the same rate, utilizing the separate pressures in such confined spaces to tend to continue the issuance of air from the second such space B at the rate at which it issues from the first as a body of non- uniform section passes through the first space and jointly utilizing such pressures to give indications of variations in cross-section of the body, substantially as they occur. Fig. 8 shows diagrammatically the arrangement of the various devices. The body to be measured, e.g. a tube, is passed through the passage 14 of the gauge A and air enters the gauge A and balance valve B from a blower 80 through orifice plates 81, 82. The balance valve B has two inlets 61, 62, two outlets to atmosphere controlled by valves worked by an air motor 70, and an outlet 68 to the differential pressure transmitter C. In operation, if the pressures in conduits 33, 68 are equal, then the differential pressure transmitter C sends air at a given pressure to a pressure controller D. If the pressure in conduit 33 changes due to variations in the tube being measured, the transmitter output pressure also changes and this affects the pressure controller D and its output changes, thus operating the motor 70 and altering the balance valve B until a balance between the pressures in conduits 33 and 68 is again achieved, when the transmitter C output pressure returns to the given value. A record of these changes is effected on a tape 83 and is used to give an indication of the variations of cross-section of the tubing. The tube gauge A, Fig. 1, consists of a circular housing having two parts 11, 12, hinged at 13, with the passage 14 for the tube being measured between them. A switch 18, 19 on the housing is normally closed, but opens when the parts 11, 12 separate. The parts 11, 12 are held closed against the action of springs 21, 22 by piston rods 23, 24, from air cylinders 25, 26. Inlet passages 29, 30, to which are connected flexible air supply hoses 31, 32, are formed in the housing 11, 12, and an outlet passage 33 is connected to the differential pressure transmitter C. To prevent damage to the housing or breakage of the tube, by bumps on a defective section of the tube, a safety gate, Fig. 6, is also fitted. This consists of two hinged plates 41, 42, held closed by spring 48 and having a passage 44 between them for the tube. When a portion of the tube strikes one of the plates 41, 42, the plate opens against the action of the spring 48 and actuates a switch, breaking a circuit connected to the cylinders 25, 26, thus opening the gauge halves 11, 12. The subsequent drop in pressure in the outlet passage 33 operates the balance valve and this actuates another switch, which closes a circuit to operate and close the plates 41, 42, by means of air motors 57, 58. This action closes the operating circuit for a timer which holds the gauge halves open for a sufficient length of time to allow the defective section to pass them and then closes them again unless the gate has again been tripped.