| Vibratory feeder is one kind of feeding construction for automatic production andassembly system. Due to good patterning performance and generality, high feedingefficiency, the feeder is widely used in automatic machining, assembly and packaging.However, the vibration source of the traditional vibratory feeder is electromagnet, whichnormally requires50Hz or100Hz in working frequency, therefore, there are disadvantageslike high power consumption and working noise, complicated structure to do adjustment,etc. With the rapid development in advanced manufacturing, the products are tending to belighter, thinner, smaller and more precise, which makes the development of novel vibratoryfeeder more and more urgent. In the end of70s in20thCentury, rectangular piezoelectricbimorph was brought up in the first time as excitation source in piezoelectric vibratoryfeeder by Japanese. In the following decades, there were series achievements coming out,and nearly10invention patents were applied in piezoelectric feeding area. And there waswide application in automation production line. Chinese researches on piezoelectricvibratory feeder started from beginning of90s last century, and there are someachievements, but no innovation compared with Japanese products, and can’t be used formass production. The paper is one task from National Project863(Project number:2006AA04Z225)“Research&Development on Vertical Driven Piezoelectric VibratoryFeeder”. Novel vibratory feeding structures on rectangular piezoelectric vibrator, roundpiezoelectric vibrator and piezoelectric transducer were brought forward. Based on thethree novel structures as the research objects, theoretical analysis, dynamic analysis,prototype design and production, experiment study were carried out. The contents in thispaper includes:1. Referring to plenty of research materials, the development status of the piezoelectricvibratory feeder home and abroad was deeply investigated. The vibratory feedingconstruction was summarized, and the piezoelectric vibrator sense and method in vibratoryfeeding construction application was pointed out. 2. Through discoursing upon piezoelectric ceramics related characteristic andperformance parameter, the performance parameter demand was obtained. Thepiezoelectric ceramics vibraiton mode fit for the feeder were defined, and also for the thepiezoelectric vibrator type, support mode, vibratory amplify form. The work here providedthe theory foudation for the feeder structure design, theoretical analysis and experimentstudy.3. The basic mechanism on material feeding from the piezoelectric vibratory feederwas explained, and the feeding affecting rules from elliptic parameter were analyzed; themovement and feeding forms during material feeding were explained, and the mechanicsmode was established, material empty out and slippage conditions and material tray affecton the movement conditons were defined, besides, the average speed formula on forwardslip condition was deduced.4. Straight-line annular piezoelectric vibrator driven feeder structure was designed, andthe working concept was analyzed; the feeder dynamics mode model was established, andthe systematic natural frequency relationship formula was deduced; based on the modeanalysis and output force deduction, the annular piezoelectric bimorph vibrator wasdesigned; the feeder supporting spring, base plate and vibratory isolation, top plate weredesigned in detail. From characteristics of frequency, voltage, amplitude and speedrelationship, single material weight, friction factor, feeding chute rise angle, springinstallation angle, noise and power consumption, and so on separately, the prototypeperformances on feeding parameters were tested on the developed straight-line annularpiezoelectric vibratory feeder, and affected rules were analyzed.5. Straight-line rectangular piezoelectric vibrator driven feeder structure was designed,and the working concept was analyzed; the feeder dynamics mode was established, andthe amplitude amplified relationship formula was deduced; dimension parameter affect ofthe rectangular piezoelectric bimorph were analyzed, rectangular piezoelectric bimorphvibration mode was analyzd with FEM software; the dynamic analysis was carried out onrectangular piezoelectric bimorph vibrator, and the affecting factors on the driving forcewas achieved. The performance was bested on the developed straight-line rectangularpiezoelectric vibratory feeder prototype.6. Straight-line langevin vibrator driven feeder structure was designed, and the workingconcept was analyzed; based on the operation requirement, the core part—langevin vibratorstructure was designed, and the structure related parameter calculation decution was done,from which the main structual dimensions of the transducer were defiend. With precisionimpedance analyzer, the impedance and resonance frequency of the piezoelectric sandwich transducer was tested; meanwhile, with laser rangefinder, the portrait amplitude in the frontside of the piezoelectric sandwich transducer was tested. From different sides like materialtype selectivity, frequency characteristic, voltage characteristic and noise and so on, thedesigned feeder prototype was tested.Combined know-how on piezoelectricity, mechanics, control science and other area inthis paper, the working mechanism and dynamics characteristics of the novel designedpiezoelectric vibratory feeder were investigated deeply, and the performance of the feederwere tested systematically. Driven mechanism of the piezoelectric vibratory feeder wasenriched by the research from this paper, which provided the theory and experimentfoundation for the feeder performance improvement and the productivity of theindependent intellectual property on piezoelectric vibratory feeder. |
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