CAD Based Predictive Models of the Undeformed Chip Geometry in Drilling
Twist drills are geometrical complex tools and thus various researchers have adopted different mathematical and experimental approaches for their simulation. The present paper acknowledges the increasing use of modern CAD systems and using the API (Application Programming Interface) of a CAD system, drilling simulations are carried out. The developed DRILL3D software routine, creates parametrically controlled tool geometries and using different cutting conditions, achieves the generation of solid models for all the relevant data involved (drilling tool, cut workpiece, undeformed chip). The final data derived, consist a platform for further direct simulations regarding the determination of cutting forces, tool wear, drilling optimizations etc. Keywords—Drilling, CAD based simulation, 3D-modelling.
Computer‐Aided Geometrical Analysis of the Fluting Operation for Twist Drill Design and Production. I. Forward Analysis and Generated Flute Profile
A computer‐aided ‘forward’ analysis, based on a typical automated flute grinder used in drill production, has been developed to study the flute generation process and the intended or design flute profile of twist drills. It has been shown that the flute grinder involved three machine setting variables and seven wheel profile variables for generating the flute for each drill specification. Based on the recommended wheel profile and machine settings, the forward analysis has shown that the flute profile was partly generated by the ‘envelope’ of the wheel profiles and partly by the locus of the point of discontinuity on the wheel profile. Furthermore, these numerical simulation studies have shown that the intended or design lip flute profile closely approximated the ideal profile for straight lip production while the heel profile closely approximated a parabolic curve tangential to the core or web diameter and passing through the heel corner. Numerical simulation of the effect of the machine settings has shown that the wheel setting angle has to be set greater than the specified helix angle in order to avoid undercutting and generate the intended flute profile for straight lip production while the other setting variables had no major influence on the generated flute profile in practice. Apart from clarifying longstanding ambiguities in the geometry and specification of flute profile of twist drills, this investigation has provided essential information for the development of the ‘backward’ analysis considered in the next paper.
Mathematical Modeling of Scour and Deposition
Electronic computers are opening up the field of sedimentation engineering by permitting the analysis of problems which heretofore have required too much time and effort. Movable stream bed profiles are being calculated in addition to water surface profiles. The initial gradation of sediment material in the stream bed may be prescribed to facilitate the calculation of an armor layer. This gradation is continually changed by the computer program in response to sediment particles being deposited on the stream bed and material on the stream bed being removed to satisfy transport capacity. Hydraulic sorting of sediment by grain size is accomodated. The stream bed does not have to be represented by a single grain size. Retardance of motion because of armor layer is calculated.