A small drill includes one chip-discharging flute which is helically formed in the exterior surface of a cutting portion of the small drill. The small drill also includes a flute-shaped portion which is formed in the front region of the chip-discharging flute in the rotating direction, which is connected to the chip-discharging flute, and which is open at the exterior surface of the cutting portion. The core diameter ratio d/D, in percent, of the small drill is set to 60% or more, and a margin a...

A masonry drill bit having an active diameter of D, comprising a shaft and a tip 1 for engaging a workpiece, wherein the tip 1 is formed with a plurality of stepped portions shaped to cut a workpiece as the drill bit rotates. By virtue of the drill bit tip 5 configuration as described and claimed herein, a masonry drill bit 1 having improved performance is provided.

A drill crown (1) used for drilling purposes, especially for rotary percussion drilling of a mouth of a blast furnace. The drill crown (1) consists of a drilling head (4) provided with a plurality of hard material or hard metal inserts (6) and a base body (2) for connection to a drive element etc. in order to drive or impinge upon said drill crown. The hard material or hard metal inserts (6) are received in bores or openings (5) of the drill head (4). According to the invention, at least one har...

An air drill includes a body having a grip portion having an air supply passage and an air exhaust passage formed therein, a trigger portion formed above the grip portion and supporting a trigger, and a cylinder portion formed above the trigger portion and accommodating an air motor. A reverse valve is disposed within the cylinder portion in order to switch the direction of rotation of the air motor between forward and reverse directions. Two reverse levers are disposed in an upper portion of th...

A plurality of chip evacuating grooves (16, 26, 36, 46a, 46b) in a vertical direction in parallel with a rotational axis of a core main body (14) are formed at an outer peripheral face of the core main body (14) in a circumferential direction from a lower end portion to an upper end portion of the core main body (14) in a cylindrical shape provided with a drilling blade (15) at a lower end edge thereof. Further, a sectional area of the chip evacuating groove (16) is formed to gradually increase ...

A drill comprising a shank part (11), which is adapted to be received in a drill holder of a drilling machine, and an opposite cutting end part (13). An intermediate fluted part (12) is provided, which defines at least one helical flute or channel (16) having a bottom surface (19) and a pair of opposite side surfaces (20) defined by the ribs or lands (17). The shape of a cross-section of the at least one flute or channel, taken at right angles to the course of the flute or channel, is such that ...

A drill bit for drilling a borehole into an earth formation is provided. The drill bit has a central longitudinal axis and a bottom surface facing the borehole bottom during drilling with the drill bit, and comprises primary fluid injection means arranged at the bottom surface and located at a selected radial distance from the central longitudinal axis, the primary fluid injection means being arranged to eject a primary stream of fluid into the borehole, the primary stream having a component in ...

A hammer drill is equipped with a connector shaft, which is rotationally driven by a motor, a spindle that transmits the rotation through a connector shaft, and a percussive impact impact mechanism that applies a percussive force in the axial direction to a drill bit held by the spindle through performing a reciprocating motion, in the axial direction, relative to a spindle that receives the rotation of the connector shaft through a motion converter mechanism. The hammer drill is provided with a...

A generally cylindrical drill, particularly an insert drill having multiple cutting inserts, helical chip grooves to clear the chips from the hole, and a gripping shank opposite the cutting end of the drill, wherein the drill experiences an unbalanced resultant transverse force upon the cutting tip of the drill, and that resultant is oriented perpendicularly to an axial plane containing the neutral axis of the maximum resistive moment at the grooved section of maximum bending stress adjacent to ...

An EDM drill is provided which includes an automated electrode tube replacing mechanism for fully automated and continuous operation. The EDM drill further includes an electrode tube guide selection device to allow the fully automated and continuous operation on holes of various diameters.