Research On Inductive Sensor For Detecting Metal Particles In Water Fluid

Abrasive water jet cutting technology is suitable for cutting a variety of materials due to its unique advantages such as no dust and no heat-affected zone.It also has the advantages of high efficiency,low cost and environmental protection,making it a very advantageous cold state Processing technology.With the development of intelligent manufacturing and science and technology,higher requirements are put forward for the processing accuracy,environmental protection and service life of water jet equipment.Because water jet technology uses water as the processing carrier,there will be solid pollutants in the fluid such as processing abrasives,cutting waste and other solid pollutants,and these pollutants are not allowed to enter the equipment circulation system,so the inlet pump water is filtered and pollutant detection,It is very necessary to understand the operating status and wear conditions of the equipment.The inductive metal particle detection sensor is a typical representative of fluid pollutant monitoring technology.It can not only measure the size of metal particles,but also identify ferromagnetic and non-ferromagnetic metal particles.At the same time,it has the advantages of simple and reliable structure and high measurement accuracy.This thesis focuses on the characteristics of water jet technology,such as large flow rate,low viscosity,and turbulent motion state,as well as the problems of uneven magnetic field strength common to existing inductive sensors and measurement errors caused by the radial position of particles.A sensor probe structure with four planar excitation coils connected in series in the same direction and an independent planar induction coil at the center position is proposed to generate a detection magnetic field with uniform radial magnetic field strength,reduce the measurement error caused by the radial position of the particles,and amplify the peak value of the measurement signal to improve Sensor detection accuracy and sensitivity.This thesis first introduces the development status and main detection technologies of fluid metal particle detection technology in detail.Secondly,the basic principle of electromagnetic induction,the magnetization effect and eddy current effect of metal particles are explained.Then analyze and compare the probe structure of the existing inductive metal particle detection sensor and its magnetic field distribution,design a five-plane coil probe structure that can generate a uniform magnetic field and amplify signal peaks,and establish a mathematical model for detecting coil inductance and particle size.Then use COMSOL software to carry out the probe magnetic field simulation research,analyze the influence of sensor parameters such as excitation frequency,coil turns and wire diameter on the output of the detection coil inductance.Determine the optimal sensor parameters under the pipe outer diameter of 3mm,4MHz,80 m A alternating excitation current,wire radius of 0.04 mm,the number of turns of the outer excitation coil is 360,the number of inner excitation coil is160,and the detection coil is 90 Turns.Simulation research shows that the probe structure can form a 70% uniform magnetic field in the detection area,and then design and manufacture the hardware and software of the metal particle detection sensor.The sensor hardware part includes the AD9850 sine signal generator,voltage polarity conversion module,and amplification and filtering.Module,LDC1000 digital inductance chip and other hardware circuits and sensor probes.The software part includes the STM32F106ZETR-based microcontroller programming based on Keil software and the host computer interface editing based on Lab VIEW.Finally,experiments verify the detection performance of the sensor.The metal particle detection sensor can effectively measure ferromagnetic metal particles with a particle size of more than 100?m and non-ferromagnetic metal particles with a particle size of 200?m.The measurement error caused by different positions in the radial direction of the particle does not exceed 16.37%,Meet the expected design requirements,can realize the monitoring of the running state of the water jet equipment.