GB800559A - Device for recording variations in the diameter of substantially cylindrical objects of considerable length - Google Patents

Abstract

800,559. Photo-electric recording of variations in diameter of cylindrical objects. COMPAGNIE GENERALE D'ELECTRICITE. April 6, 1956 [April 28, 1955], No. 10631/56. Class 40 (3). A device (see Fig. 3) for recording variations in the diameter of a substantially cylindrical object 1 comprises a measuring head, turnable about the longitudinal axis of the object and including a lamp 10 illuminating a photo-cell 13 through a window and a second photo-cell 16 directly via a mirror 32, and recording means energized by the photo-cell currents, whereby with the object stationary and the measuring head turned a curve of ellipticity in a common cross-section can be recorded, with the object moved lengthwise and the measuring head stationary a curve of variation of mean diameter in a common diametral plane can be recorded, and with both measuring head and object moving simultaneously a curve of ellipticity superimposed on a curve of variation of mean diameter can be recorded. An electric circuit arrangement (see Fig. 4) is a bridge 17 formed by four valves 18, 19, 20, 21, and photo-cells 13, 16 are connected in opposite arms; one diagonal is fed by D.C. source 22 and the other contains recording instrument 25 which may include an amplifier. In a modified circuit arrangement (see Fig. 5, not shown) a long-time-conatant network is connected via reversing switches between circuit 17 above and recording instrument 25 above; when tracing the curve of mean diameter only, the network is connected whilst it is switched out of circuit when ellipticity is traced in addition. In a further modified circuit arrangement (see Fig. 6), simultaneous and separate recording of mean diameter on a recording instrument 25 via a long-time-constant circuit 26 similar to that above, and of ellipticity on a second recorder 30 (which may be an oscilloscope) via a shunt circuit 29 with a timeconstant less than that corresponding to the rotation period of the measuring head, is possible, the bridge circuit 17 being at the input.