GB939269A - Improvements to thread measuring devices - Google Patents

Abstract

939,269. Pneumatic gauges for measuring average thread cross-sections. K.D.G. INSTRUMENTS Ltd. Oct. 13, 1961 [Oct. 15, 1960], No. 35400/60. Class 106 (2). A fluid-flow gauge for measuring the average cross-section of a predetermined length of thread comprises a groove formed by a fixed part 1, a movable part 2 and a perforated or slotted bottom 5. The thread 3 extends along the groove and is held in the acute angle between the face 28 and the grating 5 by suction exerted via the tube 30 and the tube 7. The latter connects with a chamber 38 (see Fig. 3), on one side of a diaphragm 37, a chamber 39 on the other side being also connected to the tube 30 leading to the pump. The needle valves 33 and 34 are initially adjusted so that the diaphragm 37 is in a neutral position for a thread of standard size. A departure from this size will then produce an altered air-flow through the gap 6 between the thread and the groove wall of the movable part 2, and the diaphragm will be deflected and thus complete a circuit via contact 47 or contact 48. Thus either the indicator 53 or 54 will register (according as whether the thread cross-section is greater or smaller than the standard size) and a reversible motor 50 will be operated to move the part 2 (in a manner to be described below) until the air-flow has the initial value. The amount of movement of the part 2 then gives an indication of the departure from standard size. A shaft 8 is driven by motor 50 through a belt-drive and has a lead-screw for moving a nut 12 mounted on rollers 13 across a baseplate 14. Inner portions 11 of the rollers have reduced diameter and bear against a camsurface 26 carried by: a bridge 45 which is pivotally connected at 22 to a lever plate 19 and pivots the latter about pins 17 fixed to the base plate 14 as the bridge 45 is raised or lowered by the cam-and-roller action. Arms 18 fixed to the lever plate 19 bear against spring-loaded pins 15 fixed to the part 2 and cause movement of the latter towards or away from the part 1. The shape of the cam is such as to give a reading on the indicator 9, as this revolves with the shaft 8, linear with the thread cross-section because, in general, the displacement of the part 2 will be non-linear. The thread may be fed between feed and take-up spools 55, 56 and a continuous indication of its average cross-section obtained.