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241.
Ji Zhao Jianming Zhan Rencheng Jinand Minzhong Tao 《International Journal of Machine Tools and Manufacture》2000,40(6):795
This paper develops a new ultrasonic machining system and methodology by which a robot polishes on free-form surfaces at an oblique angle with an elastic tool. On the basis of the theories of reflection of elastic waves and dynamic stress concentration, the conception is brought forward that ultrasonic elastic contact is not continuous, the physical process of the oblique ultrasonic polishing is studied and the cutting mechanism of the abrasive finish machining methods driven by ultrasonic vibration is ascribed to the joint action of the machining operation and shot-blasting. Experimental results verify that the new oblique ultrasonic polishing method by robot is an effective machining method for free-form surfaces. 相似文献
242.
A new predictive force model for a single-tooth face milling cutter with a chamfered main cutting edge has been derived. Machining tests has been conducted for fly cutting with a chamfered main cutting edge tools on plane surfaces. An S45C medium carbon plate has been used as the workpiece matrial. Force data from these tests were used to estimate the empirical constants of the mechanical model and to verify its prediction capabilities. The results show a good agreement between the predicted and measured forces.Since tool manufacturers does not provide tools with selected combinations of chamfered main cutting edge, radial angle, axial angle and inclination angles, tool holders manufactured in-house were used in the tests. The tips were prepared to the required geometry using a tool grinder. 相似文献
243.
A fixed spherical reflector tracking absorber solar collector, popularly known as Fixed Mirror Distributed Focus (FMDF) collector, is described. An analysis has been performed to study the variations in optical concentration along the absorber. Optical concentrations have been determined for cases when the sun rays strike the reflector obliquely and have been compared with the values obtained for a noon condition when the sun rays would be normal to the reflector. An elemental ring on the reflector surface is taken up for analysis to determine the useful area of the reflector that would reflect the incident rays towards the absorber. The area of the sector of the elemental ring which illuminates the absorber is determined. The effect of the reflectivity on the optical concentration is also studied. The predicted values are indirectly compared with experimentally measured surface temperatures along the absorber of a laboratory FMDF unit. 相似文献
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Mustapha Elhachimi Serge Torbaty Pierre Joyot 《International Journal of Machine Tools and Manufacture》1999,39(4):77
In this article experimental results on high-speed drilling are presented. The measurements are compared with the theoretical predictions of thrust force and torque to validate the continuous drilling model using the orthogonal cutting model and the oblique cutting model. This comparison is undertaken for the whole drill, because the lip and chisel edge are not studied separately in the experimental tests. 相似文献
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Resonance frequency of a quartz tuning fork crystal for use in chips of code division multiple access, personal communication system, and a global system for mobile communication was comprehensively analyzed by an analytical method, Sezawa's approximations and the finite element method. A comparison was also made in a more detailed and comprehensive manner among resonance frequencies calculated by the Sezawa's approximations. From the finite element method analysis results, actual tuning fork crystals were fabricated using mass-production capable positive (subtractive) photolithography, selective etching and subsequent positive (subtractive) photoresist spray coating method. A target resonance frequency of was aimed at and a general scheme of commercially available 32.768 kHz tuning fork resonators was also followed in designing tuning fork geometry, tine electrode pattern and thickness. Comprehensive comparison was made among the modeled and experimentally measured resonance frequencies and the discrepancy explained and discussed. Finite element method analysis results quite closely agreed with the experimentally measured resonance frequencies (32.676-32.933 kHz) of the fabricated tuning fork samples measured at a vacuum level of 10−5 Torr. The difference between modeling and experimentally measured resonance frequency is attributed to the error in exactly manufacturing tuning fork tine width by photolithography. However, the tuning fork design using finite element method modeling must be modified comprehensively to optimize various design parameters affecting both the resonance frequency and other crystal parameters, most importantly crystal impedance (series resistance). 相似文献