Abstract: The present invention provides a quick disconnect coupling for a work tool to a machine. The invention in its preferred embodiment provides a coupling having fluid and electrical connections and also providing alignment independent of the locking mechanism. The present invention also is advantageous in that the locking mechanism is protected from the environment when the coupling halves are not mated and also prevents a false lock-up unless the halves of the coupling are mated and aligned.

Abstract: A device for an automatic interchange and coupling of grippers on robots or manipulating devices includes a mounting member connectable to a robot and a gripper-holding interchanging plate which is formed with recesses receiving locking balls or pins interpositioned between the interchanging plate and an actuation cone of an axially movable piston positioned in the mounting member. The movement of the piston causes the actuation cone to push the locking balls or pins to move radially outwardly into the recesses of the interchanging plate to lock the latter with the mounting member.

Abstract: The present invention relates to an improved toolholder for releasably mounting on a tool support member. The toolholder is provided with a forward end for receiving a tool and a shank extending from the forward end for being releasably received in a bore of a tool support member. The shank has a first section for interference fitting with the bore of the tool support member when a rearwardly facing face on the toolholder is in abutment with a forwardly facing surface on the tool support member. The shank has a second section, rearwardly of its first section, for expansible abutment with the bore of the tool support member.

Abstract: A tool holder in a machining center comprising a basic tool holder provided with a tapered fitting hole formed on the nose portion and a small tool having its tapered fitting portion fitted detachably in the tapered fitting hole, wherein a plurality of guide holes for protruding a locking ball are formed on a circumferential wall of the fitting hole, a recess for receiving the locking ball therein is provided on a nose outer peripheral surface of the basic tool holder on which the fitting hole is formed, and a piston actuated at all times toward a base end portion of the basic tool holder is provided slidably and wherein release means for releasing the small tool from being locked by shifting the piston toward a nose of the basic tool holder is provided between the piston and the basic tool holder, a pressure chamber is formed further between the piston and the basic tool holder, and a high-pressure air from a fluid pressure source is connected to each discharge port in the pressure chamber and the fitting ho

Abstract: The mobile hand or mechanical hand is operated by a power system for driving the operative tool, and a sensor device is provided concordantly acting with the power system but having limited power, which is associated with a sight to determine a consensus to the activation of the power system when--in the absence of contrasts due to positioning irregularity of the component to be applied--said sensor device imposes an initial displacement of the same component.

Abstract: A tool such as a drill has a cylindrical shank for insertion in a tool holder of a rotary percussive or other rotary machine, such as a drilling machine. The shank has a first surface extending transversely of the shank from a point of intersection with the periphery thereof and a second surface extending from the first surface at the end of the first surface remote from the point of intersection of the first surface with the periphery of the shank to a point of intersection with the periphery spaced from the point of intersection of the first surface with the periphery. There are two sets of first and second surfaces spaced apart on opposite sides of the longitudinal axis of the shank.The first and second surfaces are flat. The second surfaces are radial and arranged on the same diameter. A plane through the longitudinal axis of the shank at substantially 90.degree.

Abstract: In a quick change spindle adapter including a power rotated spindle having a bore adapted to receive a tool holder, a body secured upon the spindle and a retractable spring biased sleeve mounted on the body having a tapered inner wall. A tool holder mounting a tool projects into the body and has a shank loosely positioned within the spindle. A tapered collar on the tool holder extends into the body and is retainingly engaged by a series of spaced balls in the body with the balls projecting into engagement with the sleeve tapered wall retaining the tool holder and shank upon the spindle. The improvement comprises a conical recess within the end of the spindle defining an axial bearing and a centering cone on the tool holder is in snug engagement and axial registry with the bearing maintaining a self-alignment of the tool holder and spindle.

Abstract: Handle adapter and chuck apparatus for a power bit includes a quick release chuck having a spindle with a longitudinally extending bore in the spindle adapted to receive the shank of the power bit. A radially extending bore extends through the spindle and communicates with the bore. A ball is disposed in the bore and contacts a portion of the shank of the power bit disposed in the bore. A spring biased sleeve is disposed about the spindle and includes a tapered bore which bears against the ball to bias the ball against the shank of the tool.

Abstract: A chuck for receiving a plain shank of a dental burr is rotatably mounted in the head of a dental handpiece and is driven by a pinion or by turbine vanes. The chuck comprises a sleeve adapted to receive the shank of a burr and provided with at least one elongate clamping claw which is movable radially between an inner clamping position and an outer releasing position. Facing grooves in the clamping claw and in an actuating member which is movable axially relative to the sleeve define a ramp way for a row of bearing balls. The ramp way extends in a direction which is generally axial but is inclined at an angle of 1.degree. to 4.degree. to the axis so that the clamping claw is moved radially by axial movement of the actuating member. The clamping claw is spring biased to clamping position and is movable to releasing position by a push button for moving the actuating member axially relative to the sleeve and thereby moving the clamping claw radially outwardly.

Abstract: The power tool has a magnetic base with superposed permanent magnet assemblies. The upper assembly can be moved relative to the lower assembly to subtract from or reinforce the magnetic field. When the sensing probe is pushed into the base the electric motor can be switched on to rotate a spindle on which a rotary cutting tool is axially mounted. The tool feed is controlled by a handle which can be mounted on either side of the tool housing. A coolant reservoir on the base has a hose connected to a pump which is connected to a manifold supplying coolant to the center of the cutting tool. The cutting tool is biased upwardly and pinches off the coolant when the tool is raised from the work. The tubular tool shank is retained on the drive spindle by balls carried by a cage and moved into engagement with a groove in the tool shank by a cam surface on a release collar spring biased to move the balls to engage the tool.

Abstract: A replaceable tool is comprised of a tool holder forming a hole providing an engageable ditch on the insert end of the shank, a fitted hole for detachably fitting the shank of this tool holder therein and a sleeve providing a plurality of locking balls to be engaged and removed from the fitted ditch of the tool holder in the fitted hole. In the interior of the fitted hole of the sleeve, the locking balls are pressed on the engageable ditch and the draw collar for applying attraction in the axial direction of the sleeve is slidably provided. When the shank of the tool holder is fitted in the fitted hole of the sleeve, the head portion end of the tool holder is designed to be pressed on the end flange portion of the fitted hole of the sleeve, and when the draw collar is pulled in the axial direction of the sleeve, the shank portion is expanded through locking balls so as to be pressed on the inner wall surface of the fitted hole of the sleeve.

Abstract: A chuck for non-circular ends of tool shanks having a bushing forming a chamber corresponding in cross-section to the tool shank and a ball which acts on the shank and is clamped by a spring biased sleeve which forms a wedge against the ball. The ball is mounted in a separate wing which is engaged by the sleeve and is displaceable relative to the bushing so that the ball engages a clamping surface formed by an end ring and the tool shank in a clamping position.

Abstract: The power tool has a magnetic base with superposed permanent magnet assemblies. The upper assembly can be moved relative to the lower assembly to subtract from or reinforce the magnetic field. When the sensing probe is pushed into the base the electric motor can be switched on to rotate a spindle on which a rotary cutting tool is axially mounted. The tool feed is controlled by a handle which can be mounted on either side of the tool housing. A coolant reservoir on the base has a hose connected to a pump which is connected to a manifold supplying coolant to the center of the cutting tool. The cutting tool is biased upwardly and pinches off the coolant when the tool is raised from the work. The tubular tool shank is retained on the drive spindle by balls carried by a cage and moved into engagement with a groove in the tool shank by a cam surface on a release collar spring biased to move the balls to engage the tool.

Abstract: An exchange chuck for exchangeably mounting a tool shank adapted for mounting a tool such as drill or tap. The tool shank is inserted to and fastened in a mounting bore formed in a tubular portion of a spindle. A movable sleeve is received on the tubular portion for movement longitudinally thereof, and plural balls are provided to the tubular portion so as to be intruded into or receded from said bore with movement of the movable sleeve, said balls operating to engage with and prevent extraction of the tool shank when intruded into the bore. An ejector member is received in the bottom region of the bore and biased forwardly at all times by a coil spring for extruding the tool shank forwardly at the time of exchange operation of the tool shank.

Abstract: A mounting chuck for attachment to a drill having a rotatable collar on a main chuck portion. The main chuck portion includes a cavity receiving therein a tool mount having a tool removably secured therein at either or both ends thereof. The mount conforms to the cavity and the collar encircles both the cavity and the mount to selectively either retain the mount in fixed position on the chuck portion or allow the mount to be removed therefrom. The chuck portion includes a hollow axially extending chamber so that one of the tools on the mount may extend into the chamber while the other tool on the mount extends out from the chuck portion in an operative position. In this manner, the tools on the mount may differ and either tool may be quickly and easily selected.

Abstract: A tool holder clamping and unclamping device utilizes a special combination of a Belleville spring biased bolt threading device to actuate a ball detent mechanism to lock a tool holder in the device.

Abstract: A tool holder for a drill capable of performing only rotary drilling or the combination of rotary and percussive drilling includes a tubular retainer member in which the shank of a tool can be inserted. Locking members mounted in the retainer member fit into recesses in the tool shank for holding it in the retainer member. During percussive drilling the locking members are axially displaceable in the recesses and the tool experiences a certain amount of axial play, however, when only rotary drilling is performed the locking members are held against axial displacement by stops so that the tool does not have any axial play. One stop forms a part of the retainer member and another stop is part of a member slidably displaceable relative to the retainer member.

Abstract: In a tool holder for securing a tool in a hammer drill in a form-locking manner, locking elements are radially displaceably mounted in a guide member. An adjustment ring is threaded onto the guide member and by rotating the adjustment ring relative to the guide member, the locking elements can be adjustably tightened or loosened. The locking elements seat in closed end recesses in the shank of the tool to be secured. The adjustment ring can be locked in different rotational positions by an interlocking tooth arrangement. Teeth are provided on the adjustment ring and on a fixing sleeve axially slidably positioned on the guide member. The fixing sleeve can be moved axially between a position for locking the adjustment ring and another position permitting the adjustment ring to be rotated relative to the guide member.

Abstract: A hammer drill for performing percussive drilling or rotary drilling includes a housing and a tool holder mounted on and axially displaceable relative to the housing, the tool holder contains a retainer sleeve mounting locking member for securing the shank of a tool in the holder. When the hammer drill is used only for rotary drilling, the retainer sleeve is displaced into contacting engagement with the housing for centering the tool holder. The tool holder includes stops for securing the locking members against axial displacement during rotary drilling. One stop is movable relative to the retainer sleeve and can be locked in position. Another stop forms part of the retainer sleeve. The stops combine with the closed ends of the recesses in the tool shank for holding the locking members against axial displacement.

Abstract: A tool holder for carrying a cutting tool is attached to a drive spindle. For purposes of making possible a rapid and easy exchange of the tool holder while at the same time there is required a small working space the tool holder is carried by an adapter, which interiorly guides a pin on the tool holder. The tool holder is clamped against the adapter by applying a clamping force on a transversal abutting surface on the tool holder.

Abstract: A quick-change holder for a machine tool wherein a nut holding a tool can be attached and detached by a single action. In the quick-change holder of the type, in which the nut charged with the tool can be attached to and detached from a holder body by the radial movements of a plurality of balls which are so loosely fitted in a plurality of radial through-holes formed in the holder body as to be made movable in the radial direction, according to the present invention, the aforementioned holder body is formed with an outwardly diverging conical inner circumference in which a spring having free wire ends with a gap therebetween so as to be compressible radially inwardly is fitted under radially inward compression in an inscribed relationship therewith, and the aforementioned spring is brought into abutment engagement with the balls, when the nut is not inserted, thereby to push the balls outwardly in the radial direction.

Abstract: In a draw-bar mechanism for moving the collet of a chuck or the like on a spindle of an automatic turning machine toward its axial clamping position and for thereafter closing the collet more slowly with greater force about a tool or workpiece to be clamped, motion is transmitted from an actuating sleeve to a draw bar or like control member by spherical thrust members movably confined between three faces obliquely inclined relative to each other. A first face is fixed relative to the spindle assembly and has one section parallel to the axis and another axially contiguous section obliquely inclined relative to the axis, the two sections merging in an exposed edge. A second face is fixed relative to the control member, and the third face is fixed relative to the actuating sleeve and has two axially consecutive sections obliquely inclined relative to each other.

Abstract: The quick-change chuck is adapted to be fitted on a shank sleeve fitted is inserted to rotate therewith. A locking nut screws on the locking sleeve and a ball sleeve is carried by the shank sleeve. The ball sleeve has an annular extension piece with locking balls in an annular groove of the locking nut. A connector bush is axially displaceably held on the ball sleeve, is subject to the axial pressure of a spring, and has inner reception part and a substantially frusto-conically converging ramp face. A detent device automatically detains the connector bush in relation to the ball sleeve in its axial release position against self-effected dropping back into the locking position under the action of the spring, and on the introduction of the locking sleeve can be over-ridden with subsequent automatic axial displacement of the connector bush by means of the spring into its locking position.

Abstract: A holder for a blade of a saber saw unit, wherein the blade is of the type provided with a pair of opposed side marginal edges and a notch in at least one side marginal edge near the rear end of the blade. The holder includes a support having a slot for receiving the blade and projecting means shiftably mounted on the support near one side margin of the slot for movement across the same and into the notch of the blade when the blade is in the slot to releasably hold the blade in the slot. Bias means holds the projection means in an operative position in the notch of the blade in the slot. A number of embodiments of the holder are disclosed.

Abstract: The present surgical tool uses high frequency impulses to replace rotating or oscillating members in cutting through or inserting materials into bone. One embodiment comprises a chisel which uses high frequency impulses to remove bone or other hard material. Because of the high forces developed, a novel holder for the chisel to the tool is disclosed. Another embodiment is a wire driver which uses high frequency impulses to drive wire into bone or other tissue. A novel holder for the wire is disclosed which allows wire to be pulled from the tool so that it can be inserted into the bone but prevents wire from slipping back into the tool during the driving operation. The chisel and the wire are driven by a novel pneumatic impulse motor. The motor includes a piston hammer which is mounted in a chamber, and air ports at either end of the chamber alternately direct air to one side of the piston hammer and to the other side of the piston hammer to drive it along the chamber.

Abstract: A quick-change drill chuck adapted for positioning ball elements within a groove circumferentially disposed about the central axis of the adapter portion of the tool. Three ball elements when pressed radially into the groove prevent longitudinal movement of the adapter, the ball elements being forced toward the adapter portion of the tool by a ramp portion formed as an integral part of the inner circumferential surface of the chuck collar member.

Abstract: The device is primarily designed to be used with vertical milling machines. This device may also be adapted to any machine tool spindle which uses an internally tapered end to hold the tool holder, collets, etc. etc. Due to the fact that this mechanism functions internally, it does not take away any of the machine's capabilities and no modifications are required to the existing spindle. Basically the device is composed of two major parts: the chuck that goes keyed inside the spindle and the air cylinder which is disposed on the side axially opposite from the chuck and fixed to the body of the machine. The chuck has an axially disposed plunger, a compression spring and two sets of spheres connected by a set of pins. The plunger is shaped to force radially outward a first set of spheres which in turn activates a second set of locking spheres to cause them to move radially inward and engage the tool holder.

Abstract: A holder of improved construction for mounting a saber saw blade on a drive means for reciprocation. The holder includes means defining a slot for receiving the blade, and means coupled with the support means for retaining the blade in the slot and for preventing movement of the blade relative to the support when the support and blade are reciprocating under the influence of the drive means. The holding means in several embodiments includes cam members which are received in notches in respective blades. Other embodiments relate to the formation of blade-receiving slots by moving wall means into proximity with recesses in side faces of elongated members.

Abstract: A bi-directional, self-tightening drill chuck suited for surgical and other medical applications in accordance with the present invention includes a chuck body having an internally tapered opening at one end that is defined by first and second cam surfaces and a central, longitudinally extending cannula or passage formed through the length of the chuck body. A plurality of tapered gripping rollers are located within the opening and are resiliently urged against the cam surfaces throughout a range of adjustment by a spring retainer which includes rearwardly extending spring arms.

Abstract: A quick-change drill chuck adapted for positioning ball elements within dimples circumferentially disposed about the central axis of the adapter portion of a tool, such as a drill, to drive the drill. A first quick-change drill chuck utilizes an axially spring-biased collar, while a further quick-change drill chuck incorporates a rotary spring-biased collar for manipulating the ball elements into and out of the dimples.

Abstract: A chuck for holding and driving fasteners such as screws or nails comprises a spring-loaded bearing sleeve with fastener-clamping balls and a spring-loaded clamping sleeve tapered to constrict the balls around the shank of a fastener inserted into the chuck, the clamping sleeve having a space to receive the balls during insertion of the fastener and for releasing the fastener, after completion of the driving operation.

Abstract: A quick-change drill chuck adapted for positioning ball elements within dimples circumferentially disposed about the central axis of the adapter portion of a tool, such as a drill, to drive the drill. A first quick-change drill chuck utilizes an axially spring-biased collar, while a further quick-change drill chuck incorporates a rotary spring-biased collar for manipulating the ball elements into and out of the dimples.

Abstract: A pneumatic hammer is provided with a quick-change retainer which may be twisted between an open position in which a tool may be inserted or removed and a closed position in which the tool is locked within the retainer. A compressible lock rod is provided to hold the retainer in at least the closed position and preferably the open position also. A stop means limits the twisting movement at the open and closed positions.

Abstract: An axially movable sleeve is retained in a bore in the nose portion of a portable rotary tool housing. The sleeve is disposed around a spindle and holds captive a ball key disposed in the spindle which releasably retains a screw driver bit or the like in the spindle bore or socket. The sleeve is releasably retained in the housing bore by a spring retainer whereby the bit as well as the retainer sleeve may be quickly removed and replaced by axial displacement of the sleeve.

Abstract: A holder for a blade of a saber saw unit, wherein the blade is of the type provided with a pair of opposed side marginal edges and a notch in at least one side marginal edge near the rear end of the blade. The holder includes a support having a slot for receiving the blade and projecting means shiftably mounted on the support near one side margin of the slot for movement across the same and into the notch of the blade when the blade is in the slot to releasably hold the blade in the slot. Bias means holds the projection means in an operative position in the notch of the blade in the slot. A number of embodiments of the holder are disclosed.

Abstract: A surgical tool has a pneumatically driven rotor motor, a source of air under pressure to drive the motor, an output system for receiving rotation from the motor and transmitting it to a bur and a securing system for securing the bur to the output system. The securing system receives air pressure from the source of air and converts the pressure to a force acting on the bur to grip the bur. The motor has a shaft mounted for rotation in a housing, and the shaft is hollow so that some of the air directed into the motor goes through the shaft and into a chamber. A piston is mounted in the housing, and when air from the shaft is directed into the chamber, it moves the piston in the chamber. The piston is connected to a collet, so that introduction of air into the chamber moves the collet. The collet has an inclined surface, and there are grippers between the inclined surface and the bur.

Abstract: A quick release drill chuck for surgical and dental instruments, particularly high speed drills powered by rotary air motors, is disclosed. The chuck engages the shafts of drills or burs and is actuated without the use of additional tools while providing a self-locking feature to insure against inadvertent loosening of the chuck.

Abstract: A quick-change drill chuck adapted for positioning ball elements within dimples circumferentially disposed about the central axis of the adapter portion of a tool, such as a drill, to drive the drill. A first quick-change drill chuck utilizes an axially spring-biased collar, while a further quick-change drill chuck incorporates a rotary spring-biased collar for manipulating the ball elements into and out of the dimples.

Abstract: A quick-change drill chuck adapted for positioning ball elements within dimples circumferentially disposed about the central axis of the adapter portion of a tool, such as a drill, to drive the drill. A first quick-change drill chuck utilizes an axially spring-biased collar, while a further quick-change drill chuck incorporates a rotary spring-biased collar for manipulating the ball elements into and out of the dimples.

Abstract: A chuck for a hand or automatic tool has a shank adapted for torque-transmitting engagement with the head of a screw or like component which is to be inserted in a workpiece and a plurality of locking elements, such as balls, radially displaceable from an inoperative position to prevent inadvertent release of the component from the chuck.

Abstract: A bit retainer for impact type pneumatic tools arranged to be mounted on the tool and to releasably receive a bit. The retainer includes a body having a bore extending therethrough. The bore includes a nose portion of generally elliptical configuration, a center portion of circular configuration and a rear portion of generally elliptical configuration that has its major axis disposed at about 90.degree. relative to the major axis of the front portion of the bore. Radially movable locking members are provided that operate in cooperation with a movable sleeve. The sleeve is movable between unlatched and latched positions which permit and prevent radial movement of the locking members to positively retain the bit unless the sleeve is intentionally moved to the unlatched position.

Abstract: A quick change tool holding assembly of the collet type is disclosed wherein a machine spindle carried collet assembly includes gripper members engageable with surfaces of a tool holder carried nut interior of the collet assembly to maintain the nut on the spindle. In order to prevent entry of coolant and other foreign matter into the interior of the collet assembly the assembly is provided with an axially extending circumferential inner diameter land below the gripper members and the nut is provided with a seal member engaging the land.

Abstract: A clamping device, especially for clamping tools in a turret or the like, in which each tool is provided with radially outwardly movable clamp elements and an actuating element carried by the tool movable axially for actuating the clamp elements. The turret in which the tool is mounted includes mechanism for driving the actuating element in actuating direction and for releasing the actuating element from actuating position to release the respective tool from the supporting turret.

Abstract: A hammer drill has a movable tool and a driving element substantially coaxial with the tool. The driving element directly transmits axial impact from the same to the tool without transmission of torque. A tool holder surrounds proximal end portions of the driving element and the tool and transmits torque from the former to the latter without transmission of axial impact. Drive means are provided for selectively imparting torque and/or axial impact to the driving element. The tool holder comprises a sleeve which surrounds the proximal end portions. The sleeve is axially movable relative to the driving element and the tool and, at the same time, are connected with them for joint rotation therewith. An additional sleeve is provided surrounding the sleeve and enabling an operator to hold and to guide the hammer drill.

Abstract: A quickly attachable and releasable assembly for attachment to a spindle head includes a plug casing insertable into the spindle head, a stop nut thereon, and two bushings loosely connected to the nut. One bushing carries a plurality of locking balls and the other bushing has a cam surface to urge the balls inwardly to engage the head. A spring urges the bushings apart to cause the cam surface to so operate.

Abstract: The multi-zone drilling system consists of a spiral drill provided, over its whole length, with continuous spiral slots and a uniform core diameter, which drill is driven by steel clamps mounted in the bottom portion of the drill chuck and engaging the spiral slot surfaces. The spiral drill is furthermore provided, at its upper end, with an annular slot pin, extractably fixed in an annular slot-locking sleeve; this annular slot-locking sleeve is in turn mounted in a pressure element which is vertically adjustable in a delicately stepped way via a connecting bush, for the purpose of altering the jutting-out length of the drill attachment in the drill chuck.

Abstract: A hammer drill has a chuck forming a tool receptacle defining a chuck axis and provided with a tool-holding element radially displaceable into a position protruding into the tool receptacle. The tool has a shank defining a tool axis receivable axially in the receptacle. This shank is formed with a radially outwardly opening recess closed at both axial ends and shaped to receive the tool-holding element, and with an axially extending groove separate from the recess and opening axially at the end of the shank. This groove has at least one flank extending substantially radially of the tool axis. A rotary-entrainment formation in the receptacle is formed with at least one side flatly engageable with the flank for maximum force transmission and minimum wear.

Abstract: Chuck for a gear reduction surgical rotary driver. There is provided for a controlled speed surgical driver an automatically releasable chuck for grasping tools of a very small diameter such as the wire used in bone pinning. In a driver having a conventional high-speed drive motor and speed reduction means, there is provided a frustro conical ramp, of generally circular cross section, and diverging outwardly toward the working end of the tool. A wire carrier is arranged for longitudinal sliding movement in the end of said tool and having a portion thereof projecting beyond said tool. Said wire carrier receives the wire centrally therethrough and carries three gripping devices which act between the wire and said ramp. Two of said gripping devices are preferably of ball shape and the third thereof is of generally disk shape with a rounded periphery whereby to project between said balls and engage a wire or other tool of small diameter.

Abstract: A releasable detent joint or coupling between telescoping cylindrical parts such as a receptacle and a tool holder held therein. The inner member is held by ball detents and a holding ring. The ring is expandable to allow release of the ball detents and separation of the parts in response to a predetermined applied torque to provide a safety release. In a simplified form of the invention, the holding ring is not expandable but release is effected merely by angular movement of the ring to a release position of the ball detents.

Abstract: A hammer drill has a chuck forming a tool receptacle defining a chuck axis and provided with a tool-holding element radially displaceable into a position protruding into the tool receptacle. The tool has a shank defining a tool axis receivable axially in the receptacle. This shank is formed with a radially outwardly opening recess closed at both axial ends and shaped to receive the tool-holding element, and with an axially extending groove separate from the recess and opening axially at the end of the shank. This groove has at least one flank extending substantially radially of the tool axis. A rotary-entrainment formation in the receptacle is formed with at least one side flatly engageable with the flank for maximum force transmission and minimum wear.