A drill bit has a shank, an intermediate shaft, and a cutting head and defines a longitudinal axis. The cutting head has a body having a front end, a rear end, and a peripheral sidewall, a primary cutting insert and a pair of auxiliary cutting inserts. The primary cutting insert is cross-shaped with a central portion with a cutting tip and four cutting arms each with a cutting edge extending radially outward from the central portion past the peripheral sidewall. The auxiliary cutting inserts are spaced radially outward from the central portion and circumferentially from the radial cutting arms, and have a cutting edge extending radially outward past the peripheral sidewall. A pair of primary dust egress slots and a pair of auxiliary dust egress slots are formed in the peripheral sidewall and configured to channel debris from the front end to the rear end of the body.

A control method for the use of a core drilling system, including a core drill and a feed device for driving the core drill along a machine holding unit, including the method steps: detecting at least one first drilling parameter value during the core drilling operation; establishing the at least first drilling parameter value as a reference value; detecting at least one second drilling parameter value during the core drilling operation; comparing the at least second core drilling parameter with the reference value; and selecting a predetermined parameter setting for the core drilling system if the second drilling parameter exceeds or falls below the reference value by a predetermined corresponding threshold value. Also a feed device for driving a core drill along a machine holding unit for use of the method, a core drill for use of the method as well as a core drilling system including a core drill and a feed device for driving the core drill along a machine holding unit for use of the method.

A control method for using a core drilling system is disclosed. In an embodiment the method includes detecting a predetermined drilling situation on the basis of the attainment of a predetermined threshold value for at least one predetermined corresponding drilling parameter and ending the core drilling operation by selecting a reverse-travel mode for removing the drilling tool from the borehole if the advancing device does not reach a predetermined threshold value for a predetermined corresponding distance value in a direction and the core drilling machine does not reach a predetermined threshold value for at least one predetermined corresponding drilling parameter or continuing the core drilling operation by selecting a predetermined operating mode if the advancing device reaches a predetermined threshold value for a predetermined corresponding distance value in a direction and the core drilling machine reaches a predetermined threshold value for at least one predetermined corresponding drilling parameter.

A device for drilling a hole with an expanded diameter includes: a body, a shank; a sleeve; a compression spring; a drill bit body; an expanded diameter hole portion forming member attached to a side surface of the drill bit body and configured such that a cutting bit protrudes laterally from the drill bit body when the expanded diameter hole portion forming member moves forward on the side surface; a compression spring, which urges the expanded diameter hole portion forming member rearward relative to the drill bit body; and a cam. The expanded diameter hole portion forming member is configured to move forward on the side surface of the drill bit body owing to rotation of the cam when the body moves forward relative to the sleeve.

A drill bit includes a body having a first end, a second end, an axis of rotation defined through the first and second end, and a body flute that extends along the axis of rotation at a helix angle. The drilling tool also includes a cutting head attached to the second end of the body. The cutting head includes a first land, a second land, and a cutting head flute. The cutting head flute is defined between the first land and the second land. The cutting head flute extends along the axis of rotation at the helix angle such that the body flute and the cutting head flute form a continuous flute.

A drill bit includes a pointed head and a bit shaft. A dust suction passage is formed in the bit shaft. A hole with an opening is formed in the pointed head or in a portion of the bit shaft, the portion being near a distal end of the bit shaft. The bit shaft includes a first portion, the first portion including a core and a rib. The core extends in an axial direction, and is thinner than the pointed head. The rib protrudes radially outward from a side surface of the core, and extends over an entire length of the first portion. The dust suction passage extends through the core in the axial direction.

Provided is a method of drilling a hole in a drilling object by using a hole drilling device 1 including: a drill bit 3 including a cutting edge on a distal end thereof; and an electric drill 2, which rotates the drill bit 3, the method including a cutting step of rotating the drill bit 3 to drill a hole in the drilling object in a state where a water-soluble gel coolant is applied to the distal end of the drill bit 3.

A drill head insert or drill head attachment, in particular a drill plate made of hard metal, for a rock drill, includes cutting edges (20, 20a) configured on the feed side which extend from a tip of the drill (18) rearward in a receding manner to an outer face (12, 14) of the drill plate (10). A drill plate (10) is substantially configured in the form of a roof when viewed from the side. A free face (24, 24a) at the cutting edge (20, 20a) abuts against a cutting face (22, 22a) along a substantial part of its extension between the tip of the drill (18) and the outer face (12, 14). A substantially smooth contour of the cutting edge (20, 20a) is interrupted by at least one projection (30, 30a, 30b) which projects beyond the cutting edge (20, 20a) in the feed direction.

A dust suction drill includes: a drill tip with cutting edge portions; a shaft joined to the drill tip and configured to rotate about an axis; and a dust suction passage that is generated when the cutting edge portions rotate, the dust suction passage being formed inside the shaft. The cutting edge portions are provided on a distal end surface of the drill tip and spaced apart from each other in a circumferential direction. Cutting edges, each of which is formed by a joint ridge between a rake face and a relief face of a corresponding one of the cutting edge portions, are arranged radially, and at a center of the drill tip, form a chisel point, which is a pointed end. A dust suction hole, which communicates with the dust suction passage, is formed in the rake face or the relief face closely to the chisel point.

A dust vacuuming drill device is adapted to be connected with a vacuum suction device by a socket, and includes a drill bit and a driven shank threadedly engaged with each other and cooperatively defining therein an internal dust passageway in communication with the socket for removing the dust generated during a drilling operation. The drill unit can be removed from the driven shank when the drill unit is broken so as to readily replace the drill unit without the need to detach the driven shank from the socket, which results in low operation and material costs.