Study On The Ultrasonic System For Thickness Measure Of Plastics Extruder

With the nation paying more attention on energy and the energy crisis coming forth,plastic products are more widely used in all trades. Plastic pipes gradually replace the traditional metal pipe in construction, industry,agriculture.Large-scale application of the pipe demands a higher quality of plastic pipe.The system,which is based on the single chip microcomputer and PLC introduce ultrasonic thickness measurement system online detailedly.Accordance with the ultrasonic spread in different materials and the actual requirements in production line,design a set from the ultrasonic acquisition,signal processing to obtain data ultrasonic thickness measurement system.This system has a broad prospect.According to the points of economics and practicality,this mainly discusses to resolve problems coming from production process.It analyses the principle and technique of plastics extrusion.Based on the fact,it brings forward the control ideas and project of the ultrasonic thickness measurement system.This system consist three parts.First: Analysis of the propagation velocity of the ultrasonic,attenuation characteristics of the ultrasonic in air and distribution of ultrasonic in plastic pipes.Put forward the method that put the ultrasonic sensor under water to measure the thickness.Choose the location and thickness measurement methods suitably.Second:Construction the ultrasonic transmits and receives circuit based on C51 SCM.This section mainly discusses the ultrasonic echo amplification, filtering and conversion circuits.Use assembly language to achieve the corresponding software functions.Gained the time difference between two impulses finally.Third:Design the communication protocol between the MCU and PLC.RS-485 chip can be used to communicate the free port of PLC and MCU serial port,reducing system cost and easy to implement.Finally the experimental data has been analyzed for the reasons of errors,and based on this,some suggestions are proposed on how to improve the system performance index.The control system for the ultrasonic thickness measurement system can supervise these real-line more robust,stable and safe.