Manufacturing Technology

Optics for the telescope were fabricated in the optical shop of the Institute. This paper describes the technology used in making the 2.34-m Telescope Optics. A polarization shearing interferometer developed for the testing of large mirrors is also discussed. 4 Refs. 51, H. Wang, H. Mi, "Light Scattering Method, Inspection of Diamond Turning Process," In-Process Optical Measurements and Industrial Methods, Vol 1266, Hague, Neth, t990. pp. 196-206. Int Soc for Optical Engineering, Bellingham, WA. A novel method for simultaneously measuring of form and roughness of the diamond turned surfaces has been developed. A laser beam has been applied to scan the surface under test, the scattering patterns have been received by a CCD array with 2048 sensor elements, the deviation o1' the specular reflection gives the information of the surface slope, which can be integrated to yield the surface form. The surface roughness is described by scattering pattern. Furthermore, the scattering patterns can also be used to diagnose the working conditions of the machine which is used to manufacture the optical surface under test. Finally some factors which have influences on the light scattering method have also been discussed. 2 Refs. 52, G. I. Harris, "Long Life Resin Bond Wheels," Industrial Diamond Review, 49(532), pp. 123-125. (Mar 1989). Phenol-aralkyl resin bond diamond and CBN wheels have been developed for both dry and wet grinding. These wheels are produced on the same equipment and under essentially the same conditions as are used with phenolic resins. The new wheel formula gives significantly improved wear life, cooler cutting and a superior workpiece surface finish. 53, G. W. Genevro, S. S. Heineman, "Machine Tools: Processes & Applications," (P-H. Dec 1990). 480 pages~ 1SBN 0-13-5434556. $52.00 54, E. V. T. Sunil, Y. C. Shin, S. Kumara, "Machining Condition Monitoring for Automation Using Neural Networks," Monitoring and Control for Manufacturing Processes, Vol PED 44, Dallas, TX, 1990. pp. 85-100. ASME, New York, NY. Machining condition monitoring is becoming an increasingly important issue in automation. Despite many successful results, this area is still not mature enough to be used for complete unmanned automation. One primary reason is the lack of complete physical models relating variables of interest in machining. In this study, two critical machining conditions, tool wear and surface finish, are extracted during machining from three components of force signals by using neural networks. It is generally known that cutting forces are related to the state of toot wear. The presence of crater wear under production conditions make it difficult to estimate tool wear from force data. The present study adopted three layer back propagation neural network for the monitoring of system conditions. The networks are first trained using the back propagation algorithm with a known set of measured data at the training stage. Off-line measurements were taken for tool wear and surface finish at pre-determined intervals. A hierarchical network architecture was chosen to represent the physical relation of variables and reduce network sizes. After training is completed, the networks are exposed to external stimuli, i.e:. cutting forces, in order to extract process conditions. Recognition of patterns can be feasible in real time. Application of the method with experimental data is also presented. 27 Refs. 55, C. Tsutsumi, K. Okano, "Machining of Ceramics (Part 4). Application of Electrolytic Dressing to Core Drill Operation," Journal of Mechanical Engineering Laboratory, 44(3), pp. 75-84. (May 1990). The electrolytic dressing method for metal-bonded diamond abrasive tools is applied to resharpening operations of core-drills for ceramics drilling. The characteristics of the working surface and the grinding performance of the electrochemically dressed core-drills are experimentally examined by comparing with those of the core-drills dressed by abrasive blocks. The experimental results show that the electrolytic dressing is effective to give better grit protrusion and that the grinding performance of the electrochemically dressed core-drill is as good as that of the drill dressed with the vitrified abrasive blocks. Moreover, the electrolytic dressing is applicable to truing for correcting geometrical irregularities of the edge of the core-drills. It is concluded that the electrolytic dressing method in which no dressing force Is generated is particularly effective to the thin, non-porous, metal-bonded diamond core-drills, while the dressing forces in the abrasive method are extremely high. l0 Refs. 56, E. L. Zivi, D. K. Anand, J. A. Kirk, M. Anjanappa, "Magnetic Bearing Spindle Control for Accuracy Enhancement in Machining, °' Monitoring and Control for Manufacturing Processes, Vol PED 44, Dallas, TX, 1990. pp. 283-297. ASME, New York, NY. Utilization of a magnetic bearing spindle can not only provide benefits of high speed machining, but can also enhance part accuracy. Error compensation, exploiting the ability of a magnetically suspended spindle to translate and tilt, within air gap limitations, provides perturbational corrective motions. This hierarchical error compensation structure was implemented using a microprocessor based error minimization controller providing real-time error compensation based on a pre-calibrated error characterization driven by on-line process monitoring. Ongoing error metrology, along with levitation system identification and modelling, provided the basis for the control system synthesis. An error compensation methodology was derived which provides the ability to correct a general class of cutting force independent, as well as, cutting force dependent, dimensional errors. The cutting process is viewed as an ordered sequence of tool path trajectories. Sharing of numerical control part program codes, augmented by handshaking functions, enables coordination of computer numerical control and error compensation functions along the tool path trajectory. Using feed forward compensation, active magnetic bearing spindle error compensation of several ~ample error sources was experimentally evaluated. 23 Refs. 57, R. C. Maydew, J. A. Leonard, N. S. Hey, "Manufacturing Technology," Sandia Technology Bulletin, l(1 ), pp. 17. (Aug 90). Welcome to this first issue of Manufacturing Technology, one of three new technology bulletins published at Sandia National Laboratories in which we seek to share information with US industry about applications of technology. Inside this issue: industry/DOE/Sandia agreement to strengthen specialty metals competitiveness; silicon micromachining produces microscopic parts: Sandia develops state-of-the-art capacitor winding machine; new robotic system spells finis to manual edge finishing; and milling assistant speeds numerically controlled machine programming. (Sandia National Labs., Albuquerque, NM 06812-3000, Report No. SAND-90-2168).

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JULY 1991 VOL 13 NO 3