β Scribed by A.S. Salama; A.H. ElSawy
No coin nor oath required. For personal study only.
A twist drill is characterized by complex geometry which is a direct function of the sharpening method used. This geometry has been studied by several investigators attempting to understand the cutting mechanism of the drill point. Each cutting lip has been considered analogous to a single edge cutting tooi in which the normal rake angle varies from positive at the outerside to negative at the innerside. Optimum performance is achievable using straight cutting lips occurring only in certain combinations of flute shape and point angle.
The chisel edge in a conventionally ground drill has no true point. This is mainly responsible for geometric errors in drilling. In a double plane sharpened drill point, a well defined chisel edge with four faces is produced. This point possesses a self centering action which facilitates drilling operations. The contribution of feed velocity to cutting velocity cannot be neglected especially at the center where they are equal.
This paper studies the working geometry of a double plane sharpened drill point, taking the effect of feed velocity into consideration. The effect of feed can be neglected at the cutting lips without a remarkable error, but cannot be neglected at the central zone.
π SIMILAR VOLUMES
In this paper, we propose a new framework to perform motion compression for time-dependent 3D geometric data. Temporal coherence in dynamic geometric models can be used to achieve significant compression, thereby leading to efficient storage and transmission of large volumes of 3D data. The displace