| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a bolt tightening force test equipment capable of accurately and easily measuring a tightening force by electromagnetically measuring a change of permeability caused by a change of a compression stress acting on a bolt head or a nut, thereby eliminating a measurement error due to individual circumstantial differences such as contact condition between a bolt shaft portion and an object to be tightened and the influences of external vibration noise. <P>SOLUTION: On the head of a bolt 2 or the peripheral portion of a nut 3 that transmit a tightening force to an object to be tightened 4 are concentrically disposed an excitation coil 8 and detection coils 6,7 wound so as to be almost orthogonal to the axial direction. An annular yoke 5 is disposed to surround the both coils so as to form a magnetic circuit in a poloidal direction with the head of the bolt or the nut. An AC current or a pulse current supplied to the excitation coil magnetizes the head of the bolt or the side face portion of the nut in the substantially axis direction, and the tightening force of the bolt shaft portion is determined by measuring an induction current induced to the detection coils in accordance with the degree of the permeability of the side face portion. <P>COPYRIGHT: (C)2012,JPO&INPIT |
