Study On Key Technology Of Quantitative Detection On Wire Rope Metallic Cross-sectional Area Damage

Wire rope is a key component of important equipment related to life and production safety,such as lifting machinery and elevators.It has an irreplaceable unique role in the process of lifting,carrying,pulling and tightening.Th e safe use of steel wire rope has important social benefits and economic benefits.Wire rope non-destructive testing is of great significance for the safe use of wire ropes and the avoidance of huge economic waste.Wire rope non-destructive testing is mainly divided into local flaw detection and loss of metallic cross-sectional area detection.With the use of steel wire ropes,local defect will expand into metallic cross-sectional area damage.Metallic cross-sectional area defect is the main basis for regular wire rope testing and elimination.Therefore,the accuracy of the detection of the metallic cross-sectional area of the wire rope is related to the safety of the wire rope.The induction coil has low cost and is durable.It is the main sensor for detection of the wire rope metallic cross-sectional area detect.However,in the field inspection,it has low detection signal-to-noise ratio with small winding number,complicated winding and installation with large winding number,detection speed has influence on output signal analysis,low axial resolution and other issues.In this thesis,we optimize the induction coil winding structure and improve the signal-to-noise ratio of the coil output signal,improve the detection resolution of the loss of metallic cross-sectional area,locate the defect and equidistant sampling without position sensor,and realize the quantitative detection of the wire rope loss of metallic cross-sectional area.The aspects of theoretical research and engineering practice are:When the induction coil is used for non-destructive testing of wire rope,its direct output signal is affected by the running speed of the wire rope.The integrator is designed to integrate the output signal to eliminate the influence of speed,and the magnetic flux passing through the induction coil is obtained to realize the quantitative judgment of the defect.The non-ideality of the device constituting the integrator,the integrator is drifting with time and temperature.For the factors affecting the drift of integrator,the method of analog digital conversion-proportional integral calculation-digital analog conversion is proposed to compensate the integral drift,and optimization of the board design also greatly reduced the integral drift.Aiming at temperature drift,a temperature closed-loop control unit is proposed to control the temperature of the main components of the integrator,which further suppresses the integral drift caused by temperature,and finally achieves the purpose of integrator long-time low drift.When the induction coil is used for non-destructive testing of wire rope,the signal-to-noise ratio of the detection signal is low,and the detection resolution is affected by the length of the detection probe.A concentrating magnetic structure with protrusions is proposed for mounting the detection coil based on the principle of magnetic aggregation and three-dimensional transient electromagnetic simulation.The structure is used for installing the coil,the magnetic aggregation structure collects and homogenizes the leakage magnetic field of the defect,and provides a path with less magnetic resistance by the protrusion for the defect magnetic flux leakage.Thereby improving the signal-to-noise ratio of the detection signal of the induction coil.An adaptive threshold method is proposed to realize the quantitative judgment of the wire rope loss of metallic cross-sectional area defect.Also given out the calculation method for the defect length.The coil detection method using the magnetic aggregation structure can eliminate the influence of the length of the detection probe on the detection resolution of the loss of metallic cross-sectional area,and has a high detection resolution.Aiming at the problems of low detection signal-to-noise ratio with small coil winding numbers,complicated installation with large winding numbers and the output influenced by the lift distance problems.A wedge-shaped iron core structure is proposed for induction coil winding based on magnetic flux leakage theory analysis and three-dimensional transient electromagnetic simulation.Which greatly simplifies the winding of the coil,reduces the influence of the lift distance between the coil and the wire rope on the detection result,and improves the signal-to-noise ratio of the detection signal.The coil output signal of the structure can realize the quantitative evaluation of the metal cross-sectional area defect without performing more signal processing,and has a higher detection resolution.The accuracy of defect sampling in wire rope non-destructive testing is related to the defect positioning and quantitative detection accuracy.At present,the combination of the guide wheel and the encoder has problems such as: slippage,idling,jitter,bounce,etc.Caused problems for defect location and equidistant sampling,And the use of the guide wheel when the wire rope is running at high speed has potential safety hazards.In this thesis,the wire rope special braided structure is used to process the output signal of the magnetic detecting component.A defect location and equidistant sampling method without position sensor is proposed,which improves the accuracy of defect positioning and equidistant sampling while avoiding the potential hazard with the use of guide wheel and encoder when wire rope running at high speed.