Showing papers in "Journal of Engineering for Industry in 1984"

Optimal Infeed Control for Accelerated Spark-Out in Plunge Grinding

Abstract: An optimal infeed control policy is proposed to minimize the cycle time in cylindrical plunge grinding. As compared with conventional infeed control consisting of roughing followed by spark-out, the proposed infeed control policy accelerates the spark-out by reducing the time required to recover the accumulated elastic deflection in the system and to reduce the infeed velocity to its final required value. This optimal infeed control policy is particularly advantageous for grinding systems having a long characteristic time constant. A practial method is described for implementing the optimal infeed control policy based upon direct measurement of the radial allowance remaining on the workpiece.

Buckling loads and natural frequencies of drill bits and fluted cutters

Abstract: The buckling loads, natural frequencies and mode shapes of twist-drill bits and certain fluted cutters under a variety of combinations of twist angle, cross-section geometry, and axial loading have been obtained. The drill bit is modelled as a twisted Euler beam under axial loading that is clamped at both ends. The governing system of differential equations is solved by the Galerkin procedure. Explicit forms for the basis functions used to generate the Galerkin coefficients are presented in general form in an appendix. They may be used for obtaining numerical results for that class of problems which use the Rayleigh-Ritz-Galerkin methods with beamtype functions as the basis functions. The representative set of modes obtained exhibit a complex out-of-plane twisting-type motion that suggests a possible explanation for the out-of-roundness of certain drilled holes.

Geometrical Adaptive Control in NC Turning Operation

Abstract: A geometrical adaptive control in an NC turning operation has been achieved by a newly developed noncontact measuring system which can continuously monitor the radius change of a workpiece in an on-line fashion. The emphasis of this system is placed on the continuous pursuits of a workpiece axis by double laser beams and the detection of the workpiece with curvatures. Satisfactory control results were obtained not only for the straight profiles but also for the curved profiles within the accuracy close to the tolerance limits of the NC machine used.

Further Investigation of Multifacet Drills (MFD’s)—Mathematical Models, Methods of Grinding, and Computer Plotting

Abstract: The geometric characteristics of nine representative Multifacet Drills (MFD’s) are summarized. Mathematical models of the various component surfaces are derived and analyzed using coordinate transformations. The mathematical models of the geometric elements are used to deduce appropriate grinding methods. Computer plots of MFD’s are also presented to check the mathematical models and to lay a foundation for future work on computer-aided design (CAD) of MFD’s.

An Analytical Investigation of the Honing Mechanism

Abstract: The cutting mechanism in the honing operation is analyzed theoretically, assuming that one stick corresponds to a single point tool with a long cutting edge. As a result, an evaluating function to present the overall severity of honing conditions and an equation to calculate the specific cutting force are derived. Moreover, some experiments are carried out to confirm the propriety of these results.

New Electrostatic Spinning Concept for Cotton

Abstract: A new compact design was developed for the electrostatic spinning of cotton yarns by use of the best technology derived from previous research conducted at the Southern Regional Research Center, New Orleans (USDA) and Battelle Columbus Laboratories. The new design consists of a miniature card-type fiber feed system, a rotating grounded tail electrode, a conical insulating chamber, and a high-voltage twisting electrode located at the apex of the conical chamber.

A Stochastic Approach to the Measurement and Analysis of Leadscrew Drive Kinematic Errors

Abstract: Approche stochastique pour la mesure et l'analyse des erreurs cinematiques d'une transmission vis-ecrou

Vented Compression Molding

Abstract: A new process, vented compression molding, is developed for molding low density particulates, such as ablative materials used in the Space Shuttle. This process is a modification of standard compression molding that uses a perforated surface as the molding surface. An excess of material is used to fill the mold cavity and this material is forced through the openings in the surface of the mold as the mold closes. This process creates frictional forces, which can be determined approximately by Mohr-Coulomb yield criterion, generating the pressure that compacts the material. The pressure in the mold is shown to be governed by the geometry of the openings and the mechanical properties of the particulate, and not by the displacement or the volume of the mold. It is determined that this uncoupling of the pressure-displacement relationship allows uniform material distribution and compaction without requiring large-scale flow of the particulates.