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: 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 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

Abstract: A shank fitting structure simple in structure and easy to machine and assemble. A shank (20) has an external diameter large enough to allow it passage in a state where a detent member (5) is moved bach radially outward, and includes a stepped portion (21) for butting by providing a small diameter portion on the end side an d a recess (23) for housing the projecting part of the detent member (5) formed in the tip part. On the internal circumferential face of an opening part (2) of an arbor A, a first sleeve (6) is provided and pressed by an elastic member (8) toward the edge of the opening in such a way that its tip comes into contact with the stepped portion (21) of the shank (20) and its external circumferential face can keep the detent member (6) back toward the external circumference.

Abstract: A multistage bit is provided with a base part having a profile of stepped conical body with its tip cut off, and with a tip drill having a blade B of the smaller diameter than the blade B which is formed on the stage 2 at the foremost end of the base part A, the latter being provided freely detachably at the tip of the base part A.The stopper S for the above multistage bit comprises a ring shaped member having elasticity in the radial direction with its free diameter slightly smaller than the diameter of each stage of the multistage bit, a part of said ring shaped member being cut, and at least one cut end 18 thereof is bent to the center side of the ring so as to be stopped in the vertical groove 19 formed on the outer periphery of the multistage bit, and the height of the ring H is constituted to be equal to or slightly higher than the height of the stage 2.

Abstract: It is the object of the present invention to drill a hole and, at the same time, transmitting an application force exactly to an undercutter for forming an undercut space in the cylindrical wall of the hole at a position near the hole bottom. An apparatus according to the present invention includes a rear circular member 1, a sleeve 10 supported in telescopic engagement with the rear member 1, an undercutter 5, and a front annular member 15 linking and movable with the undercutter 5. The sleeve 10 has an inner flange 13 forward from the rear member 1. An application force transmission mechanism 18 comprises a cam 20 supported by the rear member 1. The cam 20 has a pair of steps 21 and 22. The transmission mechanism 18 also comprises a first impact transmission rod 23 extending between the cam step 21 and sleeve flange 13, and a second impact transmission rod 24 extending between the step 22 and front member 15.

Abstract: A drill bit including a body, a drill bit fixed onto the body, a thrust transmitting member arranged on the body and having a contact portion, and an undercut cutting member housed in a guide groove provided in the side face of the drill bit. The undercut cutting member is freely movable and provided with an undercut edge at the lower end thereof. A pull-up spring is installed to operably move the undercut cutting member, and a working force transmitting mechanism is installed on the body coupled with the thrust transmitting member and with the undercut cutting member, to press down the undercut cutting member against the resistance of the pull-up spring by the approaching movement of the body and the thrust transmitting member thereby to cause the undercut cutting edge to protrude outwardly of the drill bit body surface.

Abstract: This disclosure relates to a hole cutter comprising a spindle having a rearward end shaped to be engaged and rotated by a drive machine, the spindle further having a front end and an axial center bore. A cylindrical blade is attached to the front end of the spindle. A centering pin is supported in telescopic relation within the center bore of the spindle, the pin engaging with the spindle to limit the forward movement of the pin relative to the spindle. A spring is supported in the center bore and urges the pin forwardly relative to the spindle to normally project a portion of the pin forwardly from the spindle and the blade. A center drill is attached to the front end of the spindle and projects forwardly from the blade, the drill having an axial center bore which receives the projected portion of the pin. The drill further has a bit attached to its front end.

Abstract: An anchor comprising a core including first and second ends and a cylindrical portion between said ends, the first end including means for engaging with a body to be anchored, and the second end terminating in a portion which is enlarged gradually. A sleeve engages telescopically around the cylindrical portion and has an end adjacent the second end of the core. Expanders which normally form an annulus when positioned together are provided, the annulus engaging slidably with the cylindrical portion. Each of the expanders has an engaging end which abuts on and engages with the end of the sleeve. Means is provided on the expanders for at least provisionally binding them around the core.

Abstract: An adaptor for attaching a bit to a rotary hammer drill and for attenuating the hammering force from the drill to the bit. The adaptor comprises a tubular body for engagement with the shank of a drill bit, the body having a closed rear end. Means is provided within the body at the closed end for engagement with the rear end of the shank of the drill bit to attenuate the hammering force.

Abstract: This disclosure relates to a drill including a base having a shank and a tubular core body provided with hole-cutting blades at the peripheral edges of both openings, which are coupled together via a coupling ring between the base and the end of one of the openings of the core body, allowing the selective use of both sets of the core body's hole-cutting blades for hole cutting.

Abstract: Apparatus in accordance with this invention comprises a first part adapted to be positioned in engagement with an expander of an anchor bolt, a second part adapted to be engaged by a hammer drill, and a coupling between the first and second parts. The coupling includes a guide adapted to engage a bolt of the expander and a release normally connecting the second and first parts. The guide engages the release and holds the release in engagement with the first and second parts during driving operation but disengages the release after the expander has moved a preset distance relative to the bolt.

Abstract: A drill bit has an extendable and retractable undercut portion for the drilling of undercut holes, for example to accommodate anchor bolts in concrete.The device includes a drill bit (18) for drilling an initial hold (B) to a predetermined depth at which stage a flange (12) on a guide sleeve (10) contacts the surface (A) of the workpiece. Further downward movement of the drill bit which is securely attached to a lower shank (4) of a body (1), causes relative upward movement of the guide sleeve (10) around the body (1). This in turn causes drive balls (17) accommodated within the flared upper and (11) of sleeve (10) to move inwardly and force apart tapered surfaces (3) and (6) on the body (1) and a slide sleeve (5) disposed between the shank (4) and sleeve (10).