Patent EA-001307-B1 (EA)
Title: Load indicating fastener systems method and apparatus.
Inventor: CENEY STANLEY
IPC: G01B21/32
Filed: 1998-08-17
Abstract: 1. A load measuring apparatus characterised by: an externally mounted camera or laser supported in a portable sensing head and configured and constructed for sensing a changing gap, between, on the one hand, an end face of a bar in and anchored to a base of a bore in a bolt head and shank of a fastener system and, on the other hand, a datum face of the bolt head of the fastener system, caused by longitudinal extension of the shank under strain relative to the datum face on the bolt head without contacting the relatively moving portions of the fastener system, and  a generating circuit responsive to the sensed changing pap for providing an output signal indicative of a clamp load applied to the fastener system. 2. A load measuring apparatus, comprising a camera or laser, externally removably positionable and supportable on a portable detector head atop a fastener system to be visually or light beam coupled, respectively, to a bolt head of the fastener system along an axis parallel to the longitudinal axis of the fastener system configured and constructed for sensing a changing form caused by a deflection of a first portion of the bolt head relative to a second portion of the bolt head when the fastener is under strain without contacting the sensed portions of the bolt head, and  a generating circuit responsive to the sensed changing form for providing an output signal indicative of a clamp load applied to the fastener. 3. A measuring device characterized by a portable sensing head, having a first cylindrical capacitor plate fixedly supported in the portable sensing head, externally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling to a second cylindrical capacitor plate movably supported in the fastener system to form a capacitor for use in a circuit for detecting a changing gap, measured from a reference datum plane of the bolt head of the fastener system, the changing gap being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the portable sensing head contacting the second movable capacitor plate. 4. A measuring device characterized by a detecting circuit having a first capacitor plate externally removably positionable beside a deflectable washer mounted between an integral head portion of a fastener system and a workplace, and constructed and configured for directly capacitively coupling to a second capacitor plate movably supported on the washer of the fastener system to form a capacitor for use in a circuit for detecting a changing gap between the first and second capacitor plates, the changing gap being produced when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the portable sensing head contacting the second movable capacitor plate. 5. A measuring device characterized by a portable sensing head, having multiple first capacitor plates fixedly supported in the portable sensing head, externally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling each of the first capacitor plates to a common second capacitor plate movably supported on the fastener system to form a capacitor for use in a circuit for detecting a changing form of the bolt head of the fastener system, the changing form being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit. 6. A measuring device characterized by a portable sensing head, having first, spaced apart, capacitor plates fixedly supported in the portable sensing head, externally removably positionable atop an integral head portion of a fastener system, and constructed and configured for directly capacitively coupling the first capacitor plates to a second capacitor plate a portion of which is movably supported in the fastener system to form multiple capacitors for use in a circuit for detecting a changing gap, measured from a reference datum plane of the bolt head of the fastener system, the changing gap being produced in the fastener when the fastener system is under strain and causing a variance in the capacitive reactance of the detection circuit without the portable sensing head contacting the second movable capacitor plate. 7. A measuring apparatus, comprising a portable camera or laser, externally removably positioned beside the bolt head and deflecting washer of a fastener system and is visually or light beam coupled, respectively, to a bolt head and said washer along an axis, which transverse to the longitudinal axis of the fastener system at an considerable angle senses changing of the gap or the form caused in fastener device when said fastener is under strain without contacting the parts of the device to be measured, which are under substantial relative transposition. 8. The device of any one of claims 3, 5 or 6 characterised in that, further comprises an attachment portion having an end portion for mounting the sensing head atop a head of the fastener. 9. The device of claim 8, wherein the end portion is further characterised by a recessed opening in the sensing head along its longitudinal axis terminating in a flat end face orthogonal thereto said axis for fitting around a spigot of the fastener. 10. The device of claim 8, wherein the end portion is further characterised by a magnet mounted therein. 11. The apparatus of claim 3, 5 or 6, wherein the at least one reactance capacitor comprises a pair of concentrically mounted ring capacitors. 12. The apparatus of claim 11, wherein the bottom faces of both ring shaped capacitor are equally spaced from an end plane of the sensing head orthogonal to the longitudinal axis of the sensing head. 13. The apparatus of claim 5 or 6, wherein the multiple first capacitor plates are further characterised by a cylindrically shaped capacitor mounted concentrically with a ring shaped capacitor. 14. The apparatus of claim 13, wherein t the bottom faces of ring shaped capacitor and concentrically mounted with it cylindrical shaped capacitor are equally spaced apart from an end plane of the sensing head orthogonal to the longitudinal axis thereof. 15. The apparatus of claim 13, wherein t the bottom faces of ring shaped capacitor and concentrically mounted with it cylindrical shaped capacitor are spaced apart from each other and from the end plane of the sensing head orthogonal to the longitudinal axis thereof.