Preloading a fastener of a mechanical fitting

摘要

A system for preloading a fastener of a mechanical fitting includes a strain measuring device to measure a strain on the fastener as the fastener is tightened. The mechanical fitting may include a base structure and a plate member. A support structure supports the plate member at a predetermined spacing from the base structure. The support structure may include a first sloping plate and a second sloping plate each extending between the plate member and the base structure. The fastener extends through a first hole in the plate member and a second hole in the base structure. The fastener is accessible through an opening on each side of the support structure. At least a portion of the strain measuring device is positioned relative to the fastener through a first opening of the openings to measure the strain on the fastener correlating to the preload as the fastener is tightened.

主权项

1. A system for accurately preloading a fastener of a mechanical fitting in tension when attaching the mechanical fitting to a component, the system comprising:
a strain measuring device configured to measure a strain on the fastener of the mechanical fitting as the fastener is tightened, wherein the mechanical fitting comprises:
a base structure;a plate member;a support structure for supporting the plate member at a predetermined spacing from the base structure, wherein the support structure comprises:a first sloping plate extending between the plate member and the base structure, wherein the first sloping plate extends from the base structure at a first predetermined angle relative to a plane of the base structure; anda second sloping plate extending between the plate member and the base structure, wherein the second sloping plate extends from the base structure at a second predetermined angle relative to the plane of the base structure; andthe fastener extending through a first hole in the plate member and a second hole in the base structure for attaching the mechanical fitting to the component, wherein the fastener is accessible through an opening on each side of the support structure, a boundary of the opening being formed by the base structure, the first sloping plate, the plate member and the second sloping plate, at least a portion of the strain measuring device being positioned relative to the fastener through a first opening of the openings on each side of the support structure to measure the strain on the fastener as the fastener is tightened to attach the mechanical fitting to the component, the strain on the fastener being correlated to the preload on the fastener;wherein the strain measuring device comprises:
a first strain probe; anda second strain probe at a preset distance from the first probe, wherein the first strain probe and the second strain probe are positioned between the base structure and the plate member and relative to a shaft of the fastener and measure an elongation of the shaft of the fastener as the fastener is tightened, the elongation of the shaft being correlated to the preload on the fastener.