Abstract: A drill bit has a shank (4) between a drilling head (3) and an insertable end (5) along an axis (2). The shank (4) is provided with at least two first flutes (34) that run along the axis (2) and at least a second helical flute (31). The first flutes (34) and the second flute (31) cross each other at several crossings (41).The width (35) of the first flute 34 steadily decreases over the area between two adjacent crossings (41) from one of the crossings (41) all the way to the narrowest place (42) and subsequently steadily increases all the way to the other crossing (41).

Abstract: A rotary-percussion drill includes a four-start helical shaft (3) having a fourfold rotationally and mirror-symmetrical helix cross-section, with radially projecting convexly formed helical webs (4) extending from a concave groove bottom (5) up to the envelope circle (6) and having an undercut (7) with respect to a web width (S).

Abstract: A rotary-percussion drill includes a four-start helical shaft (3) having a fourfold rotationally and mirror-symmetrical helix cross-section, with radially projecting convexly formed helical webs (4) extending from a concave groove bottom (5) up to the envelope circle (6) and having an undercut (7) with respect to a web width (S).

Abstract: A drill including a body having mortises (7), and a solid hard metal head (4) having a plurality of bits (3) and secured to the drill body over the end surface (5) of the head (4) and additionally secured to the drill body over portions of side surfaces (6) of the bits, which are located in a radially outer region of the head (4), with the side surfaces (6) extending into mortises and including first surfaces, which are associated with at least some of the bits (3) and are subjected to pressure acting in a rotational direction of the drill during operation of the drill.

Abstract: A drill including a body having mortises (7), and a solid hard metal head (4) having a plurality of bits (3) and secured to the drill body over the end surface (5) of the head (4) and additionally secured to the drill body over portions of side surfaces (6) located in a radially outer region of the head (4), extending substantially parallel to a rotational axis (A) of the drill and extending into mortise means (7), with the side surfaces (6) including first surfaces, which are associated with at least some of the bits (3) and are subjected to pressure acting in a rotational direction of the drill during operation of the drill.

Abstract: A drill including a shank (1) for connecting the drill with a drive tool, a stem (2) adjoining the shank (1) and having at most two helical discharge grooves (6, 7) opening toward a stem circumference, a head (3) provided at an end of the stem (2) remote from the shank (1) and having a diameter substantially corresponding to the stem diameter, with the head (3) having three radially extending recesses (8) provided in its free end surface and opening toward a head circumference, with the recesses being provided with at least one hard metal bit (9) provided with cutting portions (9a) extending from a central portion (9b) to the head circumference, and with the head (3), having three grooves (10, 11, 12) arranged between the three recesses (8), opening toward the head circumference, and connected with the discharge grooves.