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).

Abstract: An anchor comprising a bolt having an upper cylindrical part with an outer thread adjacent its top and a lower conical head, and a sleeve surrounding the bolt, the sleeve comprising an upper cylindrical portion and an annular expander, the expander having multiple slits therein which open to the bottom end and extend axially. The slits form expansion pieces therebetween having curvatures which, before expansion of the pieces, are substantially the same as the curvatures at the corresponding positions of the outer peripheral wall of the conical head, which the pieces contact after expansion.

Abstract: An anchor bolt comprising a bolt having an upper cylindrical part with an outer thread adjacent its top and a lower conical head, and a sleeve surrounding the bolt, the sleeve comprising an upper cylindrical portion and an annular expander, the expander having multiple slits therein which open to the bottom end and extend axially. The slits form expansion pieces therebetween having curvatures which, before expansion of the pieces, are substantially the same as the curvatures at the corresponding positions of the outer peripheral wall of the conical head, which the pieces contact after expansion.

Abstract: This disclosure relates to a drill for forming an undercut cavity in a hole in concrete, for an anchor bolt. The drill has forward and rearward ends, and comprises a body having an axially extending bore forming a generally cylindrical wall, the bore being open adjacent said forward end. A wedge center is slidably mounted within the bore, and connecting means is fixed to said center and axially slidably engages the body so that the body and the center rotate together. The center is spring-urged toward the forward end relative to the body. The body has a blade adjacent its forward end and a cutting tooth is fixed to the blade. The center has guide jaws adjacent said forward end and the jaws extend radially outwardly toward the forward end, whereby as the body moves toward the forward end relative to the center, the blade slides on the jaws and the tooth moves radially to form the cavity.

Abstract: This disclosure relates to a tool for boring or drilling holes in relatively hard, thick material such as sheet steel. The borer includes a tubular, cylindrical part having cutting teeth on one end edge. The borer part is designed to be rotated on its tubular axis and to be advanced in a forward direction to move the teeth against the material to be bored. The teeth are circumferentially spaced and are, alternately, inner cutting teeth and outer cutting teeth. The teeth are formed at the leading corners of radially thickened portions of the part, and channels or grooves are formed between the spaced teeth for the efficient removal of shavings. The teeth cut an annular groove, the inner teeth cutting at the radially inner corner of the groove and the outer teeth cutting at the radially outer corner of the groove.

Abstract: This disclosure relates to apparatus and method of forming circular holes in plate glass. A circular cut is made in the glass to a predetermined depth, which is less than the thickness of the glass by approximately 0.5 to 1.0 mm. After this cut has been made, the cutting apparatus is removed and the glass is softly struck adjacent to the circular cut in order to break loose the glass disc enclosed by the cut. The edge or margin of the hole may then be smoothed by grinding or polishing. The glass cutting apparatus includes a circular saw or glass cutter which is rotated to cut the glass. A stopper of the apparatus is adjustably mounted adjacent the cutting edge of the saw and stops the saw from cutting further after a predetermined depth has been reached. The position of the stopper may be adjusted for different thicknesses of glass.

Abstract: This disclosure relates to apparatus and method of forming circular holes in plate glass. A circular cut is made in the glass to a predetermined depth, which is less than the thickness of the glass by approximately 0.5 to 1.0 mm. After this cut has been made, the cutting apparatus is removed and the glass is softly struck adjacent to the circular cut in order to break loose the glass disc enclosed by the cut. The edge or margin of the hole may then be smoothed by grinding or polishing. The glass cutting apparatus includes a circular saw or glass cutter which is rotated to cut the glass. A stopper of the apparatus is adjustably mounted adjacent the cutting edge of the saw and stops the saw from cutting further after a predetermined depth has been reached. The position of the stopper may be adjusted for different thicknesses of glass.