Research On Assembly Quality Inspection And Diagnosis Technology Of Air-and-screen Cleaning Device Based On Wind/Vibration Signal

The air-and-screen cleaning device is the key component of combine harvester,and its manufacturing and assembly quality will affect the operation reliability and performance stability of combine harvester.According to the investigation,the fan impeller volute assembly and fan cleaning chamber assembly of combine harvester are the main factors affecting the manufacturing and assembly quality of air screen cleaning device.Through bench test and software simulation and analysis,the distribution characteristics of unsteady air flow field in fan and cleaning room,the influence rule of clearance assembly difference of impeller volute on air pressure fluctuation and the wind direction detection technology of fan outlet are studied in this paper.Based on LabVIEW platform,the software and hardware system for quality inspection of air-screen cleaning device of combine harvester was integrated and the correlation test between pneumatic parameters of cleaning device and abnormal assembly quality was carried out under the conditions of bench and machine.The specific research work of this paper are as follows:(1)Based on LabVIEW Vision image processing technology,the wind direction tracer installed at the outlet of fan is fitted and quantified.The wind direction tracer images collected by high-speed industrial camera are binarized,edges are extracted and straight lines are fitted.The wind direction angle of the outlet of fan is calculated and analyzed.The results show that the developed software and hardware for wind direction detection of fan outlet reach the expected target and the wind direction measurement error 0.5°。(2)Based on ANSYS FLUENT fluid simulation data analysis,the influence rule of fan assembly quality on air speed/air flow at outlet and the influence rule of fan-cleaning room assembly quality on air flow field parameters on screen surface in cleaning room were studied.Based on the transient simulation results,the air speed database of standard air flow field in cleaning room was established.The results show that measurement point 2 and 7 can reflect the assembly quality problem of spiral case inspection,while measurement point 3 and 6 can reflect the quality problem of blade folding angle.The effect of assembly quality of fan and cleaning room on air flow field is mainly distributed at the front and tail of screen.(3)Based on unsteady flow field theory and dynamic grid simulation results,the influence rule of clearance assembly difference between impeller and volute on air pressure fluctuation is studied,and the internal speed and pressure distribution of fan and pressure fluctuation at volute tongue under different assembly clearance between impeller and volute are compared and analyzed.The results show that when the assembly clearance changes,the pressure and flow rate changes in the internal flow field of the fan are more obvious,mainly manifested as the influence on pressure pulsation and flow smoothness.With the increase of assembly clearance,the pressure fluctuation at the worm tongue decreases severely,the pressure vortexes inside the fan increase,and the flow field inside the fan becomes smoother and worse.(4)The quality test bench of air screen cleaning device is designed and built,and the wind speed sensitivity test of fan outlet measuring point,the wind speed consistency test of cleaning room screen surface and the centrifugal fan vibration test are carried out on the test bench.The test results show that when the assembly quality changes,the wind speed sensitivity at the outlet center of the fan is higher and the uniformity of the wind speed at the symmetrical point of the screen face in the cleaning room becomes worse.The vibration of bearing seat and volute is mainly affected by offset or parallel misalignment abnormal assembly quality.(5)Based on the LabVIEW platform,the software and hardware of the quality inspection system of the wind screen cleaning device are designed and developed,including sensor and acquisition card selection,hardware integration,testing program development,and interactive interface design.The abnormal assembly test of the air screen cleaning device under the condition of the whole machine is carried out on the12kg/s feeding double longitudinal machine.The test results show that the system can detect and judge the typical abnormal assembly problems.