Mfl-testing Method And Apparatus For The Spinning Surface Of Automobile Hub Bearing

Hub bearing is an important component of automobile and generations of hub bearing have been developed. Spinning technology has been used in the manufacturing of3rd-generation hub bearing which brings potential cracks in the spinning surface. The potential cracks are great threat to the safety of car drivers thus making it significant to develop a type of non-destructive testing equipment for the crack inspection of spinning surface in3rd-generation hub bearing.In this thesis, we have carefully study the existing non-destructive methods for bearings,and basing on the study, we put forward a type of magnetic flux leakage testing method that is specifically used in the inspection of spinning surface in 3rd-generation hub bearing. A type of magnetizing apparatus basing on Yoke magnetization method of direct current has been developed for effective spinning surface magnetizing. A kind of high-sensitivity magnetic head has been selected as the sensor of this testing equipment. A sensor array has been designed to cover the generating line of the spinning surface which would ensure the covering of the entire spinning surface by scanning the spinning surface with a rotation movement. A spring has been attached to each sensor so that every sensor can fit the spinning surface precisely in the process of testing. The detector and the magnetizing apparatus are combined together with integrated designing method. We have studied the regularity of the signal discordance by conducting two group of experiments and figured out that the ratio of the peak values of different channels remains steady regardless of the depth to the cracks when the magnetizing current is within a specific value. Basing on this conclusion, a compensatory method has been put forward to help strike a balance between different channels of the detector. A subsequent experiment proves the effectiveness of this method.A testing platform has been designed specifically for spinning surface testing, in which magnetizing apparatus, detector, separation device and demagnetization apparatus are included. An efficient testing procedure has been developed to ensure the efficiency of the testing process. A controlling software is created to help operators handle the device conveniently and safely.