Study On Development Of Automated System And Detection Method For Quality Control Of Piston Pin

The piston pin,an important part of automobile engine,act as a transmitter that pass the force of piston to camshaft through the piston pin and connecting rod.The piston pin in manufacturing tends to appearing many problems such as quenching crack,low hardness,round beating,which will reduce its mechanical properties.The piston pin is liable to wear off and break even under the high temperature environment,bear the huge alternating load caused by the piston movement.Therefore,the quality of piston pin is very important for safe driving.At present,the piston pin usually adopts manual detection,which has low detection efficiency,high impact on the subjective factors of the detection result,and cannot trace the test results.In view of the current lack of piston pin detection,this paper puts forward a new method design a set of piston pin automation integrated testing system.Detection the surface crack and hardness of the piston pin by eddy current method.Detection the length and diameter of piston pin by inductance pen.Detection the surface scratches of piston pin by CCD.It can accurately detect crack,length,surface hardness,outer diameter and surface scratch of piston pin.The automatic separation of the qualified and unqualified products is realized.The main achievements and innovations are as follows:Firstly,a set of automatic integrated test system for piston pin is designed according to the test requirements of piston pin length,outer diameter,surface hardness,surface crack and surface scratches.It mainly includes mechanical structure,electric control,control host and detection instrument,which can realize the quality detection of piston pin.Secondly,according to the scheme of pneumatic piston pin diameter testing,theoretical analysis of the principle of pneumatic piston pin diameter detection method,established the mathematical relationship of outer diameter of piston pin and sensor signal based on FPGA was designed and developed the piston pin diameter testing instrument,the equipment is composed of sensor module,a control circuit and lower place machine and superordination machine of four parts.The system is calibrated and evaluated by using standard specimen and test piece.The precision of the test instrument developed is 2 mu m,which meets the requirements of engineering testing.Furthermore,based on maxwell's equations and the finite element theory,established the finite element model of piston pin eddy current testing signal and the simulation research the piston pin surface conductivity,magnetic permeability and probe between piston pin and the influence law of lift-off of the eddy current testing signal,for the study of electrical conductivity and magnetic permeability of the probe signal,the influence mechanism provides a theoretical basis.Aiming at the problem that the conductivity and the magnetic conductivity signal are difficult to decouple,this chapter presents the eddy current testing method based on the analytical model.Subsequently,the adaptive monte carlo algorithm(AMC)was used to quantitatively evaluate the uncertainty caused by random fluctuation of detection signal.Finally,numerical simulation is carried out,the results are as follows: the electrical conductivity and magnetic permeability method proposed in this chapter are correct,and excitation frequency is analyzed according to the results of the uncertainty evaluation of the impact on the test results.The research of this paper provides a theoretical basis for the comprehensive test of piston pin,especially the detection of outer diameter and surface hardness,which is of great significance in engineering testing.