A drill bit, which is rotatable in a direction of rotation about an axis of rotation, is disclosed. The drill bit has a cutting portion with an annular portion where the annular portion has a first end on which is a cutting element and has at a second end a first insertion element. The drill bit has a drill shaft portion with a cylindrical drill shaft which has at an end, towards the cutting portion, a second insertion element. In a direction of insertion parallel to the axis of rotation, the insertion elements form a plug-in connection and can be additionally connected by way of at least one pin element which is movable in at least one slit-shaped clearance.

A drill bit rotatable about a rotation axis is disclosed. The drill bit has a first drill bit portion configured as a cutting portion and has an annular portion connected at one end to one or more cutting elements and, at another end, a first connection device. The drill bit has a second drill bit portion configured as a drilling shank portion and has a cylindrical drill shaft, which on one end has a second connection device. The first and second connection devices in a connected state form a detachable connection, and a force transmission and torque transmission occur from the drill shaft portion to the cutting portion. The cutting portion has a third connection device, and the drill shaft portion has a fourth connection device. The third and fourth connection devices in a connected state form in an axial direction parallel to the axis a form-fitting connection.

The present disclosure provides an axle device and a boring tool. The axle device includes a main shaft, an expanding unit, a drill, and an engaging unit. The main shaft is magnetic. The expanding unit includes a cone blocking member and an expanding member. The cone blocking member has an inclined plane. The expanding member is limited at the main shaft and includes a plurality of pawls, wherein the pawls are against the inclined plane. The engaging unit includes a rotating member and an engaging element. The rotating member is screwed on the main shaft. The engaging element engages the drill with the rotating member. When the rotating member rotates and moves toward a first direction, the engaging element correspondingly brings the drill and the cone blocking member toward the first direction, such that the inclined plane of the cone blocking member expands the pawls outwardly.

A hole saw is movable about a rotational axis in a cutting direction to cut into a workpiece. The hole saw includes a cylindrical body having a sidewall with a first end and a second end opposite the first end. The cylindrical body also includes a gullet formed in the sidewall between a leading surface, a trailing surface, and a bottom surface of the sidewall. The trailing surface defines a portion having a first radius. The bottom surface has a second radius. The first radius is larger than the second radius. The hole saw also includes a cutting tooth coupled to the first end of the sidewall adjacent the gullet.

The present disclosure provides an axle device and a boring tool. The axle device includes a main shaft, an expanding unit, a drill, and an engaging unit. The main shaft is magnetic. The expanding unit includes a cone blocking member and an expanding member. The cone blocking member has an inclined plane. The expanding member is limited at the main shaft and includes a plurality of pawls, wherein the pawls are against the inclined plane. The engaging unit includes a rotating member and an engaging element. The rotating member is screwed on the main shaft. The engaging element engages the drill with the rotating member. When the rotating member rotates and moves toward a first direction, the engaging element correspondingly brings the drill and the cone blocking member toward the first direction, such that the inclined plane of the cone blocking member expands the pawls outwardly.

A hole saw is movable about a rotational axis in a cutting direction to cut into a workpiece. The hole saw includes a cylindrical body with a sidewall having a first end and a second end opposite the first end, a gullet formed in the sidewall between a leading surface, a trailing surface, and a bottom surface of the sidewall, and a support aperture formed in the sidewall. The gullet extends through the first end of the body. The support aperture is entirely surrounded by the sidewall. A majority of the support aperture circumferentially overlaps with the gullet. At least a portion of the support aperture is positioned closer than the bottom surface of the sidewall to the second end. The hole saw includes a cutting tooth coupled to the first end of the sidewall adjacent the gullet and an end cap coupled to the second end of the sidewall.

A surface-coated cutting tool includes a base material and a coating. A hard layer in the coating includes a plurality of crystal grains having a sodium chloride-type crystal structure. When the angle of intersection between the normal direction to (111) plane that is a crystal plane of the crystal grain and the normal direction to the surface of the base material is measured, a proportion A of the crystal grains having the angle of intersection of 0 degree or more to less than 20 degrees is 50% or more. The length of 3 grain boundaries is less than 50% of the length of 3-29 grain boundaries. The crystal grain has a layered structure in which a first layer and a second layer are alternately stacked. The total thickness of the first layer and the second layer adjacent to each other is 3 to 40 nm.

A hole saw having a blade portion separable into two parts which when separated form a base portion and a tip portion. The base and the tip have correspondingly shaped apertures and lugs that co-operate together to hold the blade tip in place. A locking means further assists in ensuring that the blade tip remains locked to the base and includes a sliding latch that engages an aperture in the blade and the base and is itself locked in place to thereby lock the blade to the base. An intermediate portion also allows for the hole saw to drill through different depths.

A drill bit which is rotatable about a drilling axis is disclosed. The drill bit has a cutting section having one or more cutting segments and a first plug-connecting element and a drill shaft section having a second plug-connecting element. The first plug-connecting element and the second plug-connecting element form a plug connection and the first plug-connecting element and the second plug-connecting element are connectable by a pin connection.

A drill bit which is rotatable about a drilling axis is disclosed. The drill bit has a drill shaft section having a first plug-connecting element and a cutting section having a second plug-connecting element. The first plug-connecting element and the second plug-connecting element form a plug connection. The cutting section includes a plurality of cutting subsections each having a ring subsection and at least one cutting segment, wherein each ring subsection together with the first plug-connecting element forms the plug connection and is connectable to the first plug-connecting element by a pin connection.