Data from experimental measurements of tool/work piece interface dynamics are presented as well as machine dynamics for the DTM at the Center.ĭiamond turning of thermoplastic polymers It contains a review of literature from conventional and diamond machining processes relating tool dynamics, material interactions and tool wear to surface finish.
This report describes the progress in defining the role of machine and interface dynamics on the surface finish in diamond turning. The results will provide systematic data with which to assess machining performance on glasses and amorphous materialsĪnalysis of the influence of tool dynamics in diamond turningįawcett, S.C. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. An aspherical machine is under development, based on the all mechanical spherical machine, but in which a ± 2 mm aspherecity may be imposed on the best fit sphere by moving the work spindle under numerical control.Ī new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. For machining hemispherical domes the axes are at right angles while for lenses with positive or negative curvature these axes are adjustable. There are two variants of this basic machine. The diamond tool is always normal to the workpiece and does not need to be accurately profiled. The machined radius of curvature is set by the alignment of the axes and the radius of the tool motion, as in conventional generation.
It employs two horizontal spindles one for the workpiece the other for the tool. The present paper describes the development of a low cost production machine based on a Bryant Symons diamond turning lathe which is able to machine spherical components to the required form and finish. Diamond turning lathes for curved surfaces however require a high capital investment which can be justified only for research purposes or high volume production. Machines for the production of flat surfaces are well established. Single point diamond machining of infra-red optical components such as aluminium mirrors, germanium lenses and zinc sulphide domes is potentially the most cost effective method for their manufacture since components may be machined from the blanks to a high surface finish, requiring no subsequent polishing, in a few minutes. Interrupted cutting experiments also provide a meant to directly measure the critical depth parameter for given machining conditions. This concept, when combined with the actual machining geometry for single-point turning, predicts that machining is a combined action of plasticity and fracture. A new process model was developed for diamond turning which is based on a critical depth of cut for plastic flow-to-brittle fracture transitions. Single-point diamond turning studies have been completed on Si and Ge crystals. (U.S.)ĭiamond turning of Si and Ge single crystals Mirror manufacturing by the single-point diamond machining process is in an early stage of development, but it is anticipated that this method will become the most economical way for producing high-quality metal mirrors. The materials from which these mirrors are primarily produced are the softer face-center-cubic structure metals, such as gold, silver, copper, and aluminum. The machines are controlled by advanced control techniques and are housed in an environmentally controlled laboratory to insure ultimate machine stability and positional accuracy. The fabrication process incorporates special quality diamond tools and specially constructed turning machines. Specular-quality metal mirrors are being machined for use in laser optical systems. International Nuclear Information System (INIS) The remaining two components, the control computer hardware and software, are discussed in detail below.ĭiamond turning on advanced machine tool prototypes It also provides front panel switches for operator override of the computer controller and implement the emergency stop sequence. Hardware interface logic couples the computers digital and analog I/O channels to the diamond turning machine`s analog motor controllers, the laser interferometer, and other machine status and control information. Axis position feedback information is provided by a Zygo Axiom 2/20 laser interferometer with 0.1 micro-inch resolution. This controller consists of four major components. The standard controller for a Pnuemo ASG 2500 Diamond Turning Machine, an Allen Bradley 8200, has been replaced with a custom high-performance design. Diamond turning machine controller implementationĮnergy Technology Data Exchange (ETDEWEB)
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