Tokyo Rope Mfg. Co., Ltd.

Sumitomo Electric Industries, Limited

Kyoto University

Tokyo Rope Manufacturing Co., Ltd.

Sumitomo (sei) Steel Wire Corp.

Kazuhiko Tsukada

Toshiyuki Moriya

Masashi Oikawa

Hiroaki Itoi

Ippei Furukawa

Sadanori Shiiki

Shinji Nakaue

Toshiro Kido

A tension measuring method installs a reel having a cylindrical coil forming part on a cable to be measured, forms a coil by winding a conductor around the coil forming part, measures a magnetic hysteresis loop of the cable by supplying a current to the coil to generate a magnetic field, and computes a tension of the cable using a parameter determined from the hysteresis loop. A magnetic field sensor and a magnetic flux sensor are provided inside a through hole in the coil forming part, and the cable is positioned inside the through hole. The magnetic field is varied so that the hysteresis loop includes a near-saturation magnetization region, to measure the hysteresis loop using the sensors. The parameter is selected from a magnetic flux or a magnetic flux density, a remanent magnetization, a coercivity, a magnetic permeability, and a hysteresis loss in the near-saturation magnetization region.

Tension measuring method

A tension measurement apparatus that can carry out tension measurement of superior reproducibility with high sensitivity even for a target object of a stranded wire structure is provided. A cylindrical magnetizer arranged to surround a portion of a long magnetic element that becomes the target object of measurement direct-current magnetizes the magnetic element in the longitudinal direction up to the range of approach to saturation magnetization. Using a Hall element (magnetic sensor) arranged in proximity to the magnetic element at the central region in the longitudinal direction of the magnetic domain, the spatial magnetic field intensity in the neighborhood of the surface of the magnetic element, greatly differing corresponding to stress variation, is detected. Based on the detection value, the tension acting on the magnetic element is measured. Accordingly, a measurement result of superior reproducibility with high sensitivity is obtained. The tension measurement apparatus is applicable even to a target object of a stranded wire structure.

Tension measurement apparatus

A detecting coil device mounted on part of a cable to evaluate the degree of corrosion of the cable, which is used, for example, on suspension or skew bridges. The detecting coil device is provided with a detecting coil and Hall elements. A magnetizer having a magnetizing coil is mounted as to enclose the cable and the detecting coil device. When current flows through the magnetizing coil, it magnetizes the cable. The magnetic field strength is detected by the Hall element, and the amount of magnetic flux passing through the cable is detected using the detecting coil. The cross-sectional area of the cable is also calculated on the basis of the magnetic field strength and the amount of magnetic flux which are detected and the permeability of the cable. The degree at which the cross-sectional area of the cable is decreased (the corrosion degree) is evaluated by comparing the calculated cross-sectional area of the cable with the cross-sectional area of a reference cable.

Method and apparatus for measuring the degree of cable corrosion

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Kyoto, Japan

Kazuhiko Tsukada