Abstract: To provide a diametrically expanded groove cutting apparatus capable of simultaneously cutting a plurality of diametrically expanded annular grooves on an inner peripheral wall of an anchor prepared hole for planting an anchor bar therein, and to provide an expandable mechanism used in the diametrically expanded groove cutting apparatus.

Abstract: A drill bit of the present invention is intended to stably perform drilling by lessening a great change in a drilling condition and to avoid reduction of a drilling efficiency even when large chip lumps are generated. In the drill bit, the main cutting blades have main cutting edges each structured such that an inner end thereof is located at the rotation center of the drill and an outer end thereof is located on an outer periphery of a rotation trace of the cutting blades, and the sub cutting blades have sub cutting edges each structured such that an inner end thereof is located to be spaced radially outward apart from the rotation center and an outer end thereof is located to be spaced radially inward apart from the outer periphery of the rotation trace toward the center of rotation.

Abstract: A water feed apparatus (20) of the present invention includes a water storage tank (40) that stores water for feeding, a pump unit (50) that feeds gas with a pressure to the water storage tank (40), and an adapter (30) that couples between the water storage tank (40) and a core drill (1). The pump unit (50) has a gripper portion (5) whose internal space is enlargingly and reducingly deformable by a gripping operation by an operator to feed the gas to the water storage tank (40). The adapter (30) has a drill-mounting portion (31b) for mounting on the core drill (1), a tank mounting portion (34) where the water storage tank (40) is mounted, a water passage (37) that connects between the drill-mounting portion (31b) and the tank mounting portion (34), and a valve unit (33) that opens and closes the water passage (37).

Abstract: An object of the present invention is to provide a drill bit whose drilling performance does not deteriorate and whose radially outer end of a blade tip is never chipped.

Abstract: To provide a user-friendly core drill which, when forming a large-diameter cut hole by the core drill with respect to an object to be drilled, such as concrete, is able to easily form, for example, a chamfered portion or a countersunk portion with respect to an opening end portion of the cut hole. In a core drill comprising a base body (1) including a shank (5) and a drill core body (2) including a drill cutting blade (13), a connection opening portion (11) of the drill core body (2) being attached to the base body (1), the connection opening portion (11) of the drill core body (2) is provided with a concave portion forming member (3) including a large-diameter hole cutting blade (15), and the large-diameter hole cutting blade (15) is provided outside the drill cutting blade (13) in a radial direction of the connection opening portion (11).

Abstract: A core cutter that enables debris generated by cutting from inside of the core cutter to be easily discharged therefrom is disclosed. A core cutter comprising a core body 4; cutting chips 1 arranged to be suitably spaced apart from each other in a circumferential direction thereof on a tip end of the core body 4 and a shank portion 2 provided at a base end of the core body 4; wherein a plurality of cutting chips 1A, 1B, and 1C arranged adjacent each other in the circumferential direction, which are included in the cutting chips 1 arranged to be suitably spaced apart from each other, protrude radially inward farther than cutting chips 1D, 1E, and 1F other than the plurality of cutting chips arranged adjacent each other.

Abstract: A novel diamond disc is disclosed. The diamond disc comprises a plurality of diamond grains 2 bound on a disc. The diamond grains 2 are arranged in such a manner that a distance m1 between diamond grains 2 which are located on a common rotational track of the diamond disc and are located forward and rearward in a rotational direction R is set longer than a distance m2 between diamond grains 2 which are located on adjacent tracks in a radial direction so as to be close to each other.

Abstract: A cutting portion structure of a core drill having diamond grains may affect deformation of a tip end portion of a cutting blade after extended use. A core drill A comprises cutting blades 2 formed at an opening end portion 4 of a cylindrical core body 1 and arranged in a circumferential direction of the core body to have gaps 3 between the cutting blades 2. As viewed from a direction substantially perpendicular to a cross-sectional view in a radial direction of the core body 1, the opening end portion 4 has an end face 4A which is rounded without edges, and diamond grains are bound on the opening end portion 4 which is rounded without edges from an inner peripheral side to an outer peripheral side, thereby forming the cutting blades 2.

Abstract: An object of the invention is to provide a core cutter that allows a wall thickness of a base to be set freely and a gallet to be formed easily.

Abstract: A drill bit constructed to improve a tip end of the cutting pointed portion to efficiently discharge chips from a center portion of a crush face of a drill hole to thereby improve cutting efficiency, is disclosed. A plurality of cutting blades 3a, 3b, and 3c are formed to be arranged in a circumferential direction of a cutting blade chip 3 formed by a cemented carbide block body. The cutting blades 3a, 3b, and 3c are each structured to have a cutting edge 4 formed by an edge between a face 6 and a flank 7 of the associated cutting blades. In this drill bit, a groove 8 is configured to be provided in a center portion of the tip end of the cutting blade chip in contact with tip ends of the cutting blade chip, and the tip ends of the cutting edges 4 have pointed portions.

Abstract: A cutting portion structure of a core drill which uses diamond grains efficiently and shows high cutting performance without deformation of a tip end portion of a cutting blade after a long-time use is disclosed. A core drill A comprises cutting blades 2 formed at an opening end portion 4 of a cylindrical core body 1 and arranged in a circumferential direction of the core body to have gaps 3 between the cutting blades 2. As viewed from a direction substantially perpendicular to a cross-sectional view in a radial direction of the core body 1, the opening end portion 4 has an end face 4A which is rounded without edges, and diamond grains are bound on the opening end portion 4 which is rounded without edges from an inner peripheral side to an outer peripheral side, thereby forming the cutting blades 2.

Abstract: An object of the present invention is to provide a drill bit which is simple in design, high in rigidity, and superior in durability and whose drilling function is in no way inferior to that of conventional drilling bits. To this end, in a drill bit comprising a cutting blade tip 2 which is united tightly to a tip end of a bit body 1 and a plurality of cutting blade portions 2a, 2b and 2c which are formed around the cutting blade tip 2, a flat surface portion 3 is formed in a side surface of the drill bit from between adjacent cutting blade portions to a base portion of the bit body 1 so that the bit body 1 is formed into a straight configuration having an approximately polygonal cross section.

Abstract: A drill bit constructed to improve a tip end of the cutting pointed portion to efficiently discharge chips from a center portion of a crush face of a drill hole to thereby improve cutting efficiency, is disclosed. A plurality of cutting blades 3a, 3b, and 3c are formed to be arranged in a circumferential direction of a cutting blade chip 3 formed by a cemented carbide block body. The cutting blades 3a, 3b, and 3c are each structured to have a cutting edge 4 formed by an edge between a face 6 and a flank 7 of the associated cutting blades. In this drill bit, a groove 8 is configured to be provided in a center portion of the tip end of the cutting blade chip in contact with tip ends of the cutting blade chip, and the tip ends of the cutting edges 4 have pointed portions.

Abstract: A novel diamond disc is disclosed. The diamond disc comprises a plurality of diamond grains 2 bound on a disc. The diamond grains 2 are arranged in such a manner that a distance m1 between diamond grains 2 which are located on a common rotational track of the diamond disc and are located forward and rearward in a rotational direction R is set longer than a distance m2 between diamond grains 2 which are located on adjacent tracks in a radial direction so as to be close to each other.

Abstract: A shank attaching structure with as less axial free movement as possible and of a simplified construction, a cutter for use with the shank attaching structure, and a cutter for use with the shank attaching structure which is free from an incident that the cutter becomes incapable of coming off even if an impactive rotating torque is exerted thereon, are intended to be provided, wherein the shank attaching structure is constructed such that in a state restricted by a restriction mechanism for restricting a depth to which a shank (7) is inserted into an arbor (A), the position of an engaging portion (7B) relative to the lock member (5) is axially deviated toward the open side of a shank attaching bore to bring the lock member (5) and the engaging portion (7B) into abutment with each other on the base end side of the shank attaching bore.

Abstract: A drill bit of the present invention is intended to stably perform drilling by lessening a great change in a drilling condition and to avoid reduction of a drilling efficiency even when large chip lumps are generated. In the drill bit, the main cutting blades have main cutting edges each structured such that an inner end thereof is located at the rotation center of the drill and an outer end thereof is located on an outer periphery of a rotation trace of the cutting blades, and the sub cutting blades have sub cutting edges each structured such that an inner end thereof is located to be spaced radially outward apart from the rotation center and an outer end thereof is located to be spaced radially inward apart from the outer periphery of the rotation trace toward the center of rotation.

Abstract: It is an object to provide a locking device of a core drill which automatically locks a core body when the core body is attached to a base body, the coupling relation between the base body and the core body being fixed unless an unlocking operation is performed by an act of worker, wherein in the core drill including the base body and the core body which are connected to each other by the engagement of an engagement projection with an engagement concave portion, an engagement pawl of the locking device is disposed on the base body, and under the condition that the engagement projection engages the engagement concave portion, the engagement pawl being biased by a compression spring is caused to descend to a back portion of the engagement projection to fix the engagement projection within the engagement concave portion thereby locking the core body.

Abstract: An object of the present invention is to provide a drill bit capable of easily drilling a drill hole that has no rifling, and has high circularity, can be easily positioned, the drill bit comprising a cutting blade tip which is composed of a block body of cemented carbide, three cutting blade portions are formed circumferentially equidistantly around the cutting blade tip, a connection line between a cutting surface 5 and a flank surface 6, said cutting and flank surfaces being formed in each said cutting blade portion 4a, 4b, 4c, acts as a main cutting edge 8 whereas a connection line between a connection surface 7 and said flank surface 6 acts as an auxiliary cutting edge 9, said main cutting edges 8 and said auxiliary cutting edges 9 cross at a blade tip point 10 so that said blade tip point 10 is shaped like a peak with no chisel edge, each said auxiliary cutting edge 9 lies on a line extending from said main cutting edge 8 of a said cutting blade portion located opposite across said blade tip point 10, a