بررسي نيروي محوري در فرآيند سوراخكاري ارتعاشي

چكيده انگليسي :

Investigation of thrust force in vibration drilling process Hossein paktinat h paktinat@me iut ac ir March 3 2012 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiAlireza Fadaei Tehrani mcjaft@cc iut ac irNaser Nehzat n nehzat@cc iut ac irAbstract Vibration Drilling VD is a process that longitudinal wave is used for improving drilling conditions Inthis process high frequency more than 16kHz and low amplitude often 2 to 30 m is applied on toolwhile the engagement between tool and workpiece during machining process is connected and disconnected This process against of ultrasonic drilling with the help of abrasive grains can be used for variety ofmaterials whether ductile or brittle In ultrasonic drilling ultrasonic vibrations is transmitted to the abrasivegrains suspended in a slurry via ultrasonic head and material removal is effected by the help of oscillatingabrasive grains that accelerate and impact on the workpiece surface repeatedly The material removal in thisprocess UD is done by brittle fracture mechanism Therefore this technique is applicable for brittlematerials while VD can be used for both brittle and ductile materials In this study the rotary vibrationdrilling tool was designed and fabricated for performing Vibration Drilling VD This tool is able to applylongitudinal wave through ultrasonic transducer and horn to a drill in a rotary mechanism After primary testsand checking up the design and fabrication of tool set up the effect of longitudinal wave in vibration drillingof Al2024 T6 was studied and compared with Ordinary Drilling OD The major objective of this study isthe comparison of thrust force in both vibration and ordinary drilling process Also some parameters likechip burr circularity and cylinderisity of the ultrasonically and conventionally drilled workpieces weremeasured and compared In the first step the first half of hole depth was done by vibration drilling then thevibration was switched off by generator and the next half of the hole depth was completed by ordinarydrilling After obtaining good results then for every desirable cutting speed and feed rate the complete holewas drilled with vibration i e vibration drilling and again with the same parameters another hole wascompleted without vibration i e ordinary drilling The achieved results show a drastic reduction in thrustforce in vibration drilling rather than ordinary drilling In vibration drilling the oscillation motions of tool actlike a chip breaker and cause the chips transform into discontinuous chips or because the impacts that are hitto chips the vibro impact mechanism chips tend to change their morphology In vibration drilling process the chip adhering is declined that is because the length of chip contact with drill is reduced and thereforecause the reduction of friction Burr formation is a negative factor in drilling process and has always been achallenge to industry In vibration drilling burrs can be eliminated without additional operations In drillingprocess for enhancing hole precision and performing drilling process exactly in defined place centre hole isneeded The drill skidding in vibration drilling technique is almost eliminated and the drill is pierceddownward quickly and more easily The enhancement of surface finish in vibration drilling because of built up edge reduction or elimination is also considerable Keywords Drilling Ultrasonic Al2024 T6 Vibration drilling

پاك طينت، حسين

بررسي نيروي محوري در فرآيند سوراخكاري ارتعاشي

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