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.
Trends in the Development of Machinery and Associated Technology ” TMT 2012 , Dubai , UAE , 10-12 September 2012 GEOMETRIC MODELING OF TWIST DRILLS
Accurate geometric models of twist drills are needed to determine the required grinding wheel profile for generating a given drill flute profile design, as well as, for finite element simulations of the drilling process. This paper presents a method to create accurate models of two-flute conical twist drills using analytical equations to generate drill flute profile needed for production of twist drills with straight lips and solidmodeling techniques to generate geometric models of twist drills. Boolean operations are used to mimic the drill manufacturing steps and generate the fully designed drill.
An Analytical Study of Three Point Grinding Methods for General Purpose Twist Drills
This paper presents ‘acceptable grinder criteria’ for assessing the potential of drill point grinding methods for general purpose twist drills. The criteria are based on geometrical requirements involving the shape and the recommended values of the commonly specified drill point features of conventional general purpose drills as well as the ability of the grinder to independently achieve the specified features. Three plausible drill point grinding methods are considered, namely; the ‘plane flank’, the ‘cylindrical flank’ and the ‘conical flank’ methods. The relevant analyses relating the commonly specified drill point features to the grinding parameters are presented and used to assess the three grinding methods by means of the above criteria. It is shown that for the ‘plane flank’ grinding method, the drill point geometry is over-specified and the acceptable grinder cannot be satisfied. For the ‘cylindrical flank’ method the drill point geometry is uniquely specified although only very few combinations of the values of the specified drill point features meet the acceptable grinder criteria. In contrast, the ‘conical flank’ analysis indicates that the drill point geometry is under-specified but that the acceptable grinder criteria can be satisfied for most values of the specified drill point features. It is concluded that the first two methods are unsuitable for general purpose drill point sharpening while the ‘conical flank’ method is most promising. The criteria proved to be essential for assessing the sharpening methods.