Online Detection Of Spherioidization Quality Of Nodular Cast Iron Of Steering Knuckle

The mechanical properties of steering knuckle of nodular cast iron are determined by its ball quality,and the traditional method of sample detection such as metallographic method and stretching method cannot meet the needs of on-line detection.For the same material,the initial permeability is also determined by its ball quality.So in this paper,a new method for determining the ball quality of steering knuckle based on initial permeability is proposed.Established an on-line detection system and proposed a evaluation model to evaluate its reliability.The detection system consists of sensor probe,circuit and propulsion mechanism.The sensor probe is the core of the whole detection system which used to convert initial permeability to electronic signal.Existing studies always use inner loop sensor which can be only used to detect the initial permeability of rod sample.In this paper a U type with magnetic core is designed which can be applied to detect any sample with a small piece of test area.The design of U type sensor extended the usage of initial permeability.The propulsion mechanism includes three parts of the thruster,lead rail and attitude adjustment mechanism which can realize the automatic detection when the sample reaches.In the design,the lead rail ensures the attitude of probe and the attitude adjustment mechanism can guarantee the Contact quality of the probe and sample.The circuit part mainly includes the excitation signal generator,the detection signal acquisition and the control section,and realizes the whole system work flow control and signal processing.The excitation sinusoidal signal is generated by the DDS chip and converted into AC constant current source.The signal from the sensor probe is amplified and filtered by the detection signal acquisition part,and then sampled with high speed AD.The control part includes the whole system work flow control and signal extraction.In order to validate the reliability of online quality measuring system for car steering knuckle spheroidizing quality and carried out a serious of studies on influencing factors,such as the condition of contact between probe and sample,sample materials and circuit noise.The results show that the influence cased by contact condition and sample materials complied by normal distribution while the effect resulted by circuit noise was negligible.Therefore,this paper built the detection model based on the conclusion above and figured out that the error detection probability was less than 0.46% and false detection probability was less than 0.31%,which has confirmed the feasibility of this system,too.