The Research Of More Than 30mm Detectingdistance Testing Device For Wire Rope

Wire rope is a slender and vulnerable ferromagnetic component which bears the most load and is related to the safety of life and property.In the long-term use process,defects such as cross-sectional area loss and broken wires caused by wear will inevitably occur,so it is very important to realize nondestructive testing of wire rope.With the continuous improvement of safety awareness,wire rope inspection is used in more and more scenes.In order to realize the real-time performance of wire rope inspection without affecting normal production activities,wire rope inspection must develop from off-line handheld to in-service inspection.In-service detection equipment runs under high load for 24 hours.At present,the existing detection lift-off distance is very small(2mm-5mm).Combined with the structural thickness of magnetic sensitive elements,usually the inner cavity of the sensor is directly attached to the detected steel wire rope.As a result,the magnetic flux leakage sensor of steel wire rope will scrape off the oil stain on the surface of steel wire rope and even get stuck by the warping wire on the surface of steel wire rope.Therefore,it is very important to realize that the magnetic flux leakage sensor of steel wire rope can detect steel wire rope at large lift-off(> 30mm).However,with the increase of lifting distance,the field strength of damaged leakage magnetic field decreases exponentially;Even if the magnetization is enhanced by increasing the number of magnetizers,there is a problem of drowning weak damage signals due to noise interference such as twisting rope,wire rope swing and background working conditions;The frequency of wire rope damage is affected by many factors,such as damage type,size and running speed of wire rope,which makes signal processing difficult.In this paper,aiming at the related difficulties of detecting steel wire rope with magnetic flux leakage sensor in large lift-off(> 30mm),a magnetic sensing and coupling method of weak signal is proposed by combining simulation and a large number of experiments.The characteristics and parameters of magnetic sensitive elements are analyzed and compared,and their array arrangement is reasonable.The noise such as rope signal is differentially processed at the extraction end of defective magnetic leakage field,which improves the signal-to-noise ratio of signal source,reduces the difficulty of subsequent signal processing and indirectly improves the sensitivity of sensitive elements.Secondly,by using the analog signal processing method of weak signals,the appropriate frequency response space is designed.Combined with the noise interference encountered in the practical application,the shielding layer and grounding technology are targeted to enhance the anti-interference ability of the testing equipment,improve the signal-to-noise ratio and further improve the overall testing ability of the wire rope nondestructive testing system.Finally,the testing system is tested,and the test shows that the steel wire rope can be detected with large lift-off(> 30mm),and the magnetic sensing and coupling method of weak signal and the analog signal processing method of weak signal are diverged to other minor damage detection.