Life decision manner of steel wire rope for crane

摘要

PROBLEM TO BE SOLVED: To decrease the replacing cost of a wire rope by making it possible to perform the accurate judgment of the life of the wire rope. SOLUTION: The ratio of the result of the computation of the breaking life of a wire by the Niemann method and the actual bent number of the wire is made to be the life ratio data. The ratio between the result of the strand- torsion test of the wire (the excessive wound part in manufacturing or after use), which has not passed a sheave and the result of the strand-tension test of the wire, which has passed the sheave, is made to be the deterioration life data, and the correlation-curve drawing of the life ratio data and the deterioration rate data is prepared beforehand. When the life of the wire is judged, the ratio between the result of the strand-torsion test of the excessive wound part and the result of the strand-torsion test of the wire, which has passed over the sheave, is obtained as the present deterioration test, and the present life rate corresponding to the present deterioration rate is obtained from the above described correlation curve. Then, the remaining life of the wire is obtained from the relationship between the actual bent number of the wire and the present life rate, and the life is judged.