| As the most important equipment of the mechanical machining field.NC machine tool the manufacturing industry of the country.Recently,the manufacturing industry has the new development direction of intelligence.The development of NC machine tools take on more apparent intellectualization trend.As a base of NC machine tool intellectualization,machine status monitoring is a means of guaranteeing the machining quality and managing the health of machine.Therefore,it's necessary and significant to develop a type of on-line monitoring system for machine tool,which can monitor the status of NC machine tool by multi-sensor.This thesis focus on the development of the on-line monitoring system.The CompactRIO,vibration,acoustic and thermal sensors and other devices have been intergraded to a hardware platform of monitoring system.Then the multi-level and high-efficiency software,which have the functions of acquisition,display,analysis,storage,transmission,has been developed based on LabVIEW software development environment.The validity of the monitoring system has been verified through machining experiment.The relationship between signal values and machining parameter has been found.Based on experiment,relational model between surface roughness of workpiece and strength of vibration signal has been established.Surface roughness alarm function has been realized by applying the relational model.Specific content are as follows:Firstly,a multi-sensor highly-integrated hardware platform of monitoring system was built.For the requirement of the NC machine monitoring,the function and object has been identified.The vibration and thermal characteristic of spindle and acoustic characteristic was chose as monitoring object.According to the principle,performance,and placement condition,the appropriate type of sensor has been selected.For the requirement of environment,sensors and functions,NI CompactRIO has been chosen as the core of hard system.The platform,data acquisition card,power supply,sensor wires and other devices have been integrated packaged to a highly-integrated hardware platform of monitoring system.Secondly,according to the requirement of monitoring and condition of hardware,the software of monitoring-acquisition system has been developed.Programming work follow the FPGA-Real Time-Host 3levels in LabVIEW programming environment.The program on FPGA realized that 2 sequence structure collect dynamic signal quasi-static signal by Interaction with data acquisition card.The program on Real-Time realized the processing,analysis,storage,updating of several channels of signals by multi-producer/ multi-consumer structure.Host program could receive data by TCP/IP and display all information.Thirdly,the monitoring system was used on the experimental analysis of side milling of thin-wall structure.The compare of time-domain waveform of vibration signal,of acoustic signal and the surface quality of workpiece has been found.The stable temperature condition of spindle during machining process has been confirmed.Making effective value(RMS)and extreme value as standard of the strength of acceleration signal and acoustic signal,the relationship between the strength of acceleration signal,acoustic signal and machining parameters as spindle speed,radical cutting depth and feed rate.The relationship between acceleration signal and acoustic signal in the time-domain and frequency-domain has been analyzed.Finally,for the requirement of surface roughness control,the relational model between surface roughness of workpiece and strength of vibration signal has been built.The relationship between surface roughness of workpiece and strength of vibration signal has been analyzed after defining the source and factor of surface roughness of milling.The regression equation was built by the roughness and vibration data from machining experiment.The model was validated by significant validation and normal probability of residual elements.The on-line surface roughness alarm mechanism in the monitoring system based on the model. |
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