Cryogenic diamond turning - Theory and experiment

Cryogenic diamond turning - Theory and experiment

design is considerably simpler than most optical profilometers and may represent the most affordable method of profilometry with nanometric resolution...

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design is considerably simpler than most optical profilometers and may represent the most affordable method of profilometry with nanometric resolution available. 15 Refs., 6 Figs. 8. Morita, Noboru; Watanabe, Takehiro; Yoshida, Yoshitaro. Crack-free Processing of Hot-preeeed Silicon Nitrlde Ceramics Using a Pulsed YAG Laser (Fracture strength end residual stress). JSME International Journal, Series 3: Vibration, Control Engineering, Engineering for Industry. 1992 Dec; 35(4): 667-672. This paper describes the effect of crack-free laser processing of hot-pressed silicon nitride ceramics on fracture strength and residual stress. The fracture strength of the processed test pieces was determined by three-point bending tests. The residual stress in the processed surface was characterized by X-ray diffraction measurement. The strength of the laser-processed workpieces was reduced to 90-80% compared with that of the ground workpieces because of subsurface layer damage, which included the heat-affected layer and the residual stress layer. In particular, the latter greatly affected the fracture strength because the higher compressive residual stress layer generated during grinding was released by laser processing. It is concluded that the newly developed crack-free processing technique has great industrial possibilities. 9 Refs. 9. Evans, C. J; Polvani, R. S; Whiteton, E; Lundin, R. L; Stewart, D. D; Paul, E. S. Cryogenic Diamond Turning Theory and Experiment. Proceedings of the Seventh Annual Meeting of the American Society for Precision Engineering 1992. This paper reports on single point diamond turning which is a mature technology applied to a wide range of products. Very rapid tool wear, however, renders the process inapplicable to a number of materials, notably ferrous metals. Many authors have attributed this rapid wear to chemical processes, although there has been little agreement in the literature about the exact nature of the chemical interactions. The rate of chemical reactions increases exponentially with temperature. Thus, a reduction of toot tip temperature should result in reduced wear rates. We have constructed diamond tuming and fly-cutting systems in which both tool and work-piece may be chilled using enclosed flows of liquid nitrogen. There are considerable experimental difficulties associated with measurement of the actual cutting temperature (i.e. the temperature at the diamondwork interface), ti. 10. Yokoi, N; Namba, S; Takai, M. Damage of STM Tips During Nanofabricetlon. Advanced Materials for Optics and Electronics NA TO ASI Workshop on In-situ Processing;, 1927 Apr. 1; Viana do Castelo, Portugal; 1993 Feb; 71-7. The STM tip shape was found to change when nanofabrication using a scanning tunnelling microscope (STM) was attempted by applying voltage pulses between the tip and the sample. This change, which is considered to be caused by the voltage pulses, was studied systematically to investigate the thermal contribution to nanofabrication using STM tips. The tips become easily damaged as the pulse amplitude and pulse width increase or the tunnelling gap decreases. Thermal reaction, including thermochemical reaction, is considered to play an important role in such nanofabrication. 11. Saijo, K; Yagi, M; Shibuki, K; Takatsu, S. Deposition of Diamond for Cutting Tool Applications. Materials and Manufacturing Processes. 1993; 8(1): 59-73. The poor adhesion of diamond film to substrates is one of the major problems for practical use in a cutting tool (1-4). In this study, sintered tungsten carbide (WC) body without Co metal, not cemented carbide, was used as the substrate (5), and the effects of surface decarburization of the substrata for improvement in the adhesion of diamond films were investigated. The surface decarburization and diamond coating were carried out in a microwave plasma CVD system. From the results of several adhesion tests, including the cutting tests, it is concluded that the good adhesion is obtained by surface decarburization of the substrata before diamond coating. The reasons for improvement in adhesion are considered by observing the interface structure between the film and the substrata. The damage mechanism of diamond coating on cutting an A1-18%Si alloy with increasing cutting speed is also discussed. 17 Refs. 12. Yang, Renyi; Jouaneh, Musa. Design and analysis of a low profile micro-positioning stage. Precision Machining: Technology and Machine Development and Improvement- Production Engineering Division. New York, NY: American Society of Mechanical Engineers; 1992: 131-142. Vol. PED 58. In precision joining processes, such as laser welding, there is need for low-profile, high stiffness, vertical motion positioning stages. Piezoelectric actuators with their smooth motion, infinite resolution, and high stiffness offer an attractive choice for use as driving elements in these stages. However, directly employing a piezoelectric actuator to produce the required motion for precision joining applications requires the use of a very long actuator ( > 200 mm) which would interfere with the tight tooling workspace. This paper presents detailed analysis and design of a new low profile, single-axis, piezo-driven vertical motion micro-positioning stage. The stage is constructed from flexure hinges and uses a lever to transfer the horizontal motion of a piezoelectric actuator into vertical motion of the stage. The design employs a novel configuration of a hinge pivot to improve the motion accuracy of the stage. A strategy to select the driving actuator based on maximizing the motion range of the stage is also presented. As an illustration, the design of a stage with a motion range of 100 lim, a stiffness of about 20 N/pm in the moving direction, and a low profile height (= 70 mm) is presented. A finite element simulation of the stage is also performed to verify the stage behavior. The results show that the stage behaves in a linear fashion, has a high accuracy with a maximum straightness error and yaw error or < 0.4 lim and 0.004 mrad, respectively, and a high stiffness in the transverse direction ( > 120 N/lim ). 7 Refs. 13. Koenigsberger, F. Design Principles of Metal Cutting Machine Tools. Franklin; 1964 Jan. ISBN 0-08-010106-2. $140. 14. Samuel, Francois J; Farnoux, Bernard; Ballot, Benedicte; Vidal, Bernard. Development and industrialization of eupermlrror multilayere used for neutron guides. Proceedings of SPIE - Neutron Optical Devices and Applications. Bellingham, WA: Int. Soc. for Optical Engineering; 1992: 54-66. Vol. 1738. Great improvements have been made in realizing super-mirrors multilayers, but only on laboratory scale samples. In particular, supermirrors with a cut off twice that of natural nickel and a reflectivity higher than 97% on (10 x 4) cm 2 substrates have been obtained. To use such supermirrors in the PRECISION ENGINEERING

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