A drill includes a substantially cylindrical bit body 10 having an axis O. The bit body 10 has a flange portion 13 which includes a converging portion 13a which reduces its diameter progressively towards the front end of the bit body and a flange 13b which is provided with a rearwardly facing annular surface 13c. The annular end surface is contactable with the front end surface of a drill holding portion of a machine too. Chip discharging flutes 14A,14B, each having an inner surface constituted by first and second inner surface portions 14a,14b and a third inner surface portion 14c arcuately recessed therefrom, are formed in the front end portion of the tip body 10. An inner peripheral cutting insert 16A and an outer peripheral cutting insert 16B are mounted on the ends of the chip-discharging flutes 14A,14B. The cross-sectional area S.sub.A of the first-mentioned chip-discharging flute 14A is determined to be greater than that S.sub.B of the second-mentioned chip-discharging flute 14B. A plurality of grooves 25 are formed in the third inner surface portion 14c so as to extend along each chip-discharging flute.
The invention concerns a drill including a generally cylindrical body, tipped with a head and provided, over at least part of its length, generally spiral evaporating grooves. The groove(s) are delimited, over at least part of their length, by a succession of facets, attached to one another, and linked to one another by sharp edges or by radius blends.
A helix drill for metal chip removing machining includes a shank which defines a longitudinal rotary axis and has front and rear ends. The front end carries two cutting edges. Two chip flutes are formed in an outer periphery of the shank and extend helically rearwardly from respective cutting edges for conducting chips. Two coolant channels extend within the shank for conducting cooling fluid. A major part of the length of each cooling channel is straight and oriented parallel to the axis. A total helical twist of each of the chip flutes along the length of the shank is about 30.degree..
A spiral drill includes a rear shank portion; a front tip; and a spiral (helical) middle portion extending therebetween. Spiral ribs are formed in the middle portion, and coolant channels extend through the drill to the tip for conducting coolant fluid. The coolant channels form exit openings in the tip which are spaced at different radial distances from a centerline of the drill. Each coolant channel extends spirally through a respective rib, and the portion of each coolant channel disposed in the shank is straight. Those straight portions are spaced by different radial distances from the centerline.
A cutting tool, especially a drill, milling cutter, screw tap, reamer and core drill, comprising a shaft and a cutting member on which at least one cutting edge is provided for machining a workpiece, the cutting member being provided with a slide layer which has a lower hardness than a base layer of the cutting member.
A complex cutting-blade tool wherein a neck having a smaller diameter than the diameter of the drill thereof is connected to a shank. At the place where the drill and the neck are connected is provided a burr removal cutting blade inclined roughly 45.degree. from the tool center axis. A hole entrance beveling cutting blade is also mounted through fixture to the neck, inclined at an angle of roughly 45.degree. from the tool turning center axis, in a direction opposite to the burr removal cutting blade. The fixture can be secured at any position along the length of the neck, wherefore the distance between the burr removal cutting blade and the hole entrance cutting blade can be suitably adjusted so as to correspond to the depth of the machined hole (i.e. the thickness of the workpiece).
