Method of measuring axial force of bolt and instrument for measuring axial force of bolt
US8583383B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jan 20, 2011 |
| Grant date | Nov 12, 2013 |
| Priority date | — |
| Expiry date | Nov 5, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L5/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A bolt-axial-force measuring method and instrument capable of easily and precisely measuring an axial force of a bolt are provided. The bolt is screw-joined and coupled to a piston of a bolt tensioner, and a hydraulic pressure is supplied to its pressure chamber so that the bolt is elongated by applying a tensile force equal to or more than a necessary bolt-fastening force. A nut separating from a fastened member due to the elongation of the bolt is seated again on the fastened member, and the hydraulic pressure in the pressure chamber is discharged to release the tensile force of the bolt. A pressure change of the pressure chamber from which the hydraulic pressure is discharged is detected by a pressure sensor, a point where a change rate of the pressure change detected by a measuring apparatus is suddenly reduced is detected as an inflection point, and a pressure value of the pressure chamber at the inflection point is multiplied by a pressure receiving area of the pressure chamber, whereby the axial force of the bolt is calculated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.