画像処理によるロープの健全性評価に関する基礎的研究

摘要

平成23年7月，地下鉄の駅に設置されたエレべータにおいて，ワイヤロープが破断する事故が発生した.事故調査報告書によれば，事故原因として，比較的短期間で外から検査しにくい内部断線が生じ，強度が低下したこと，錆に関する具体的な判定基準や内部断線に対応した検査方法がなかったことなどが挙げられている.また，本事故を受けて実施された調查検討において，ワイヤロープの強度低下は素線断面積の減少と関連していることから，ワイヤロープ直径による劣化判定が提案された.その後，定期点検で最も摩耗している部分の直径計測や赤錆の有無の確認を実施するようになった.通常，直径計測や赤鲭の有無の確認は訓練された技術者により行われるが，昨今の産業界における事故や安全確保に対する国際的要求に鑑みれば，検査の均質化，検査結果·評価の集中管理が求められる.%A hoist rope rupture accident of an elevator in a subway station occurred in 2011. According to the accident report, the causes were deterioration of strength of the wire rope by breaks of inner wires, ana insufficiency of the inspection method regarding breaks of inner wires and red rust on the wire ropes. Although detection of the breaks of inner wires is difficult, the breaks relate to the decrease of diameter of wire rope and an occurrence of red rust. Therefore measurement of diameter of wire ropes and confirmation of the occurrence of red rust are required in periodic inspection at present. In general, diameter of wire ropes is measured by vernier calipers, and red rust is checked with eyes. However it is preferable to measure and check more accurately and homogenously from the viewpoint of recent accidents and global requirements. This study deals with development of a soundness evaluation system of wire rope by image processing. The system consists of a digital camera and a computer. The camera takes digital images of wire rope. The computer analyzes the digital images and calculates the diameter of wire rope from the digital images. Additionally red rust is also checked by analyses of the digital images. In this paper, a concept of the system and verification using wire ropes were described as a fundamental study of development of the system. As a result, it was confirmed that the system has adequate accuracy of diameter measurement and red rust detection.