A drill comprising: a groove (15, 120) chip discharge in form of a spiral with respect to a ejeformado on the outer periphery of the tip section of a body (11, 110) of the aproximadamentecilíndrico rotating bit around its axis, and an edge (16, 130) formed cutting ridgeline intersectanteentre a surface of the wall that faces the direction of drill rotation of this groove (15, 120) devirutas output and a sidewall (14, 113) of the tip body (11, 110) of the drill, in which, together with the section on the tip side of the continuous groove (15, 120) of output chips, where the edge (16,130) cutting a section (18) of small width, in which the helix angle relative to the axis and anchuradel groove are constant, a section (20) of increasing width is formed in the groove (15, 120) of devirutas output towards the rear end side of this narrow width section, characterized porquedicha section (20) Anchu increasing ra comprises a spiral groove having a larger helix angle and unsurco coil having a smaller helix angle than the helical angle of section (18) pocaanchura or virtual groove (19A), wherein the section (18) small width extends extremoposterior, in which the spiral grooves on the side of the direction of rotation of the bit and on subsequent ellado in the direction of drill rotation of the virtual groove (19A) are formed, and in the a section of the dearista line is formed in the section where these spiral grooves overlap, while the height of the R section dela ridgeline is large in the rear end side of expanding width section it ygradualmente becomes smaller towards to the side of the tip body (11, 110) of the drill.
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