Abstract: A zero-deflection support chuck is provided for gripping a load shaft which includes a stable support body having a bore, a gripping sleeve closely embracing the load shaft and a pressure sleeve within the bore and surrounding the gripping sleeve. The outer surface of the pressure sleeve is exposed to a pressure medium from a pressure source. The outer surface of the pressure sleeve has sealing lands at each end cooperating with the ends of the bore and a spiral groove and lands extending between the sealing lands. The lands between the grooves have the same diameter as the bore in the body. Pressure in the spiral grooves and the inner surface of the body bore moves the gripping sleeve tightly against the support shaft along the entire length of the sleeves and locks the shaft in a stable position.

Abstract: A tool holder including a drive unit having a peripheral flange about the outer end thereof, and interchangeable chuck units with similarly configured flanges for selective engagement against and releasably mounting to the drive unit flange by screw fasteners. Each chuck unit includes a self-contained fluid pressure system comprising a recess inward through the outer end thereof defined by a flexible peripheral wall with a sealed cavity therebehind. The cavity is filled with a fluid which, upon being pressurized, produces a corresponding inward flexing of the recess wall for the gripping of a tool bit.

Abstract: Tool holder connection arrangement for modular tools holder devices of a tool machine for connecting a first hollow element, provided with an internal threading and having a cylindrical axial seat, to a second hollow element provided with a shank insertable in the cylindrical axial seat of the first element. The connection arrangement includes a shaft having threading engageable with the internal threading of the first hollow element, the shaft defines a seat for receiving a clamping wrench. A tongue arrangement is provided for torsionally blocking the second element relative to the first element. A crown of balls arrangement is provided for axially blocking the second element with respect to the shaft. The shaft includes a circumferential groove and the shank includes a circumferential groove for receiving the crown of balls arrangement.

Abstract: A clamping arrangement is disclosed for an annular milling cutter comprises a receiving flange which has a centering collar concentric with the axis of rotation. With the aid of clamping means the milling cutter is held on the receiving flange and positively connected to the latter by at least one engaging member. To enable the gripper of a tool changer to have unobstructed access, a pressure flange carrying a number of radially protruding teeth on its rim is provided, axially movable by an actuator rod selectively operated by an actuator. The milling cutter has in its central opening radially inwardly protruding teeth, the spacing of which corresponds to the spacing of the teeth on the pressure flange. By setting the position of the teeth offset relative to one another, the milling cutter can be moved over the pressure flange, and rotating the cutter to align the teeth, the pressure flange can clamp the milling cutter against an abutment surface on the receiving flange, acting through the aligned teeth.

Abstract: An abrasive disc exchange apparatus for use in a vertical spindle grinding machine includes a cover member surrounding an abrasive disc, and has an opening disposed in a radial direction of the abrasive disc for the passage of the abrasive disc therethrough. The cover member has a lid for closing the opening, and the lid is movable into an open position where the lid opens the opening. A guide rail accommodating device is provided for accommodating a guide rail. A support device is provided for holding the guide rail horizontally so as to allow the guide rail to extend toward the spindle housing when the lid is moved to its open position. An abrasive disc-carrying slide carries each of the upper and lower abrasive discs, and is engageable with the guide rail for movement therealong into and out of the space below the spindle housing when the guide rail is disposed horizontally.

Abstract: A tool holder assembly includes a first member formed with a cylindrical bore and a second member including a cylindrical portion receivable in the bore of the first member. A locator screw hole extends radially through the first member. The second member is formed with a conical face having a centerline perpendicular to its longitudinal centerline. A locator screw is threaded into the locator screw hole in the first member. The locator screw includes a conical nose adapted to engage the conical face of the second member when the locator screw is turned in a first direction. The locator screw cooperates with the conical face of the second member to radially locate the second member with respect to the first member.

Abstract: A rotary tool is provided with a shank and a collar-like section, and further includes a plurality of screw-threaded holes drilled in a vertical end face of the collar-like section, in parallel relationships with the axis of the collar-like section. A plurality of balancing weights are removably screwed in the holes as required to balance the tool.

Abstract: A tool holder and spindle adapter includes a quick change section for securing into a power spindle, a body having an axial bore mounting a positive drive and a collet holder shank to receive a tool holder collet and tool, with the tool extending into operative engagement with the positive drive. A rotatable tool adjuster is mounted within the body upon a transverse axis and includes an eccentric cam device engageable with the positive drive for controlling longitudinal in and out adjustments of the tool.

Abstract: An expandable tool holding device for holding a tool or workpiece in which the clamping force is brought about by the solidification and expansion of a fusible alloy. The alloy is contained in an expansion chamber defined in part by a thin-walled, expansion sleeve. The alloy has a low melting point and expands when it solidifies. The pressure caused by expansion of the fusible alloy radially expands the expansion sleeve causing the expansion sleeve to grip the tool or workpiece. To release the tool, the alloy is heated and liquified so that the expansion sleeve returns to an unexpanded condition.

Abstract: The present invention concerns a mounting device with conical shank, particularly a 7/24ths cone, for cone-to-surface application for attachments, tool holders and tools, essentially constituted by a cone (1) for introduction in the spindle (2), by a front part (3) centered in the cone (1) and provided with a flange (4) for application against the face of the spindle (2), by a knob (5) for assembly of the cone (1) in the front part (3) and by an elastic pressure unit (6) of the cone (1) in the spindle (2) in locking position, mounted in compression between the said cone (1) and the front part (3), characterized in that it is provided with an elastically deformable means (7) applying the front part (3) forcibly in the cone (1), in locking position.

Abstract: A tool component adapted to be connected to another element of a tool assembly includes a rearwardly facing surface and a truncated conical recess extending rearwardly therefrom. The recess is adapted to receive a correspondingly configured projection of the other element. A portion of the rearwardly facing surface defines a support surface engageable with the other element. The recess is non-circular in cross-section so as to be rendered non-rotatable relative to the other element. The recess includes a rearwardly open hole extending along the axis and a threaded fastening bolt disposed in the hole to draw the projection into the recess.

Abstract: A tool chuck assembly comprising a collet having a bore for supporting a tool, a collet holder having a portion circumscribing the collet, a tension nut cooperatively associated with the collet holder to mount and dismount a tool means defining a coolant channel in the collet holder, a sealing element mounted in the collet having a first peripheral sealing surface (8) engaging the inner wall of the collet holder to form a seal behind the collet and a second peripheral sealing surface engagably with the outer periphery of the tool to form a seal therewith.

Abstract: The present invention concerns a mounting device with conical shank, particularly a 7/24ths cone, for cone-to-surface application for attachments, toolholders and tools, essentially constituted by a cone (1) for mounting in a spindle (2), by a front part (3) centered in the cone (1) and provided with a flange (4) for application via its rear face against the front face of the spindle (2), and by a knob (5) for assembly of the cone (1) and the front part (3) by means of an intermediate threaded element (6), on which bears an elastic unit (7) formed of Belleville washers intended to apply the cone (1) in the spindle (2) in locking position and mounted in compression between the said cone (1) and the front part (3), characterized in that it is provided with a device (8) for locking of the mutual position of the cone (1) and the front part (3), in mounting position in the spindle (2) with application of the flange (4) against the face of the said spindle (2), by gripping at least two balls (9) between the said co

Abstract: A machine tool has a machine tool body (3), a spindle (1) having a supporting portion (2) and being rotatably supported by the machine tool body (3), and a tool holder (5) having an inserting portion (6) attached to the supporting portion (2). A coating layer (10) made of a hard material including titanium is provided on the supporting portion (2) of the spindle (1) and/or the inserting portion (6) of the tool holder (5).

Abstract: The present invention relates to a system for attaching a tool holder to a machine tool which includes an automatic hook-up of an electrical, pneumatic or hydraulic connector to supply power to the tool holder. The system includes an attaching sleeve slidably mounted on the tool holder mounting stud. A spring interposed between the mounting stud and the attaching sleeve exerts a biasing force on the attaching sleeve. The power connector is separable and has a portion attached to the machine tool and a mating portion movably attached to the tool holder. A pin interconnects the attaching sleeve and the movable mating portion of the connector.

Abstract: A tool head is clamped in a tool holder by rotating a radial or axial clamping shaft which has spiral camming surfaces urging clamping elements outwardly to engage ramps on the pin of the tool head which is received in a socket of the tool holder. The spiral cam can be a second or higher order mathematical curve and the shaft can carry an ejection cam as well.

Abstract: A fast tool change holder is provided for holding a tool adapter onto an internally delivered coolant spindle. The holder comprises an expandable split collet which can be inserted into the tool adapter and expanded in order to hold the adapter onto the spindle. The split collet has an expandable bladder therein which receives a coolant fluid from the spindle and expands under the pressure of the coolant fluid radially outwardly for expanding the split collet. The bladder enables the coolant fluid to assist mechanical and centrifugal forces associated with the split collet to hold the tool adapter onto the spindle.

Abstract: An improved tool holder system and method of using the same is disclosed, characterized by use of a plural extension member assemblies which permit the rapid adaptation of conventional machine tool holders for use in both automated machine tool changers as well as manual machine tool changer systems. In addition, the present invention discloses an improved method of mounting a cutting tool within a tool holder to accurately position the cutting tool height within the tool holder and subsequently prevent any backing out of the cutting tool from the tool holder during the cutting operation. Further, an improved apparatus and method of ensuring concentric mounting cutting tool within a tool holder is disclosed.

Abstract: An adapter sleeve, the diameter of which is altered by means of the pressure of a fluid, whereby, as a result of this change in diameter, an object is held by means of the clamping force of the adapter sleeve, characterized in that the adapter sleeve is made of titanium or a titanium alloy and comprises a hard layer on the side which is adapted to clamp the object.

Abstract: A machine spindle is formed with an axially centered forwardly flared large-diameter seat, provided in the seat with at least two axially and radially displaceable spindle jaws, having an axially displaceable actuating rod axially coupled with the jaws, and formed with cam formations engageable with the jaws to move same together on axial rearward displacement. A transfer body or a tool is normally also centered on the axis and formed with an axially centered rearwardly tapered small-diameter stem substantially smaller than the seat.

Abstract: A clamping device for releasably securing a tooling adaptor in a tool clamp block comprising a generally cylindrical member having an eccentric slot for engaging and securing the tooling adaptor, the cylindrical member adapted to move in the direction of its longitudinal axis to reversibly load and engage the tooling adaptor.

Abstract: A tool change mechanism in a machine tool includes a tool change arm arranged to attach a protection cover member to the forward end of a spindle head for protection of a ring secured to the forward end of a tool spindle in the spindle head and to remove the protection cover member for replacement with a tool holder of large diameter. The tool change arm is further arranged to insert the tool holder into the tool spindle and remove it from the tool spindle, the tool holder having a ring gear secured thereto for meshing engagement with the ring gear of the tool spindle and a protection cover part integrally formed therewith to be coupled with the forward end of the spindle head for protection of the ring gears meshed with each other when the tool holder has been inserted into the tool spindle. The tool change arm has a pair of tool grippers each having a first grip portion for engagement with the protection cover member and a second grip portion for engagement with the tool holder.

Abstract: The invention relates to a tool components and a method of assembling tool components. One tool component comprises a central recess and a fastener. The recess is non-circular in cross-section. Another tool component has a central projection and a central threaded bore in its axially rear end. The projection is non-circular in cross-section.

Abstract: To center a tool restrained within a collet coupled to a driven portion (9) which, in turn, is coupled to a driving portion (2), and to compensate for possible axial offsets of the respective portions, a coupling element connects the driving and driven portions and two first spring elements (23, 24) are located on the driving portion, two further spring elements (31, 32) are located on the driving portions offset with respect to the first spring elements of 90 degrees. Each one of the spring elements can be adjusted with respect to a centrally located counter support portion (29, 31) by adjustment screws passing through the spring elements and bearing against the counter support, to thereby position the axis of the driven portion (9) carrying the collet, in congruence with the axis of the driving portion (2) even if there are manufacturing tolerances or other offset conditions, such as tolerances in the tool clamped in the collet.

Abstract: A cutting tool for a lineal milling machine has a female tapered surface for close tolerance matching to the outer, male tapered surface on the outside of the spindle which mounts the cutting tool to provide the maximum width of support for the cutting edge. The cutting edges comprise a plurality of carbide inserts, each with its own flute formed in the body of the tool, such that as the cutting tool is rotated at high speed an annulus of cutting surface is created which is ideally suited for use with the following method. A new method for lineal machining includes the steps of advancing the cutting tool into the workpiece to form a substantially arcuate edge, retracting the cutting tool from the workpiece, indexing the cutting tool to an overlapping position, and then advancing the cutting tool into the workpiece to remove the amount of overlap, with those steps being repeated to mill pocket openings or for any other lineal milling application.

Abstract: To permit easy coupling and uncoupling of a concrete or rock circular boring or milling tool element (14, 17), two coupling parts (1, 2) are provided, a first coupling part (1) being formed with a recess (7) of non-circular cross-sectional shape, for example of approximate four-leaf clover shape, extending inwardly from an end face (11) of the first part; the second part (2) has a projection (20) of non-circular cross-sectional shape, matching the cross-sectional shape of the recess, and fitting therein, while being axially separable therefrom. The engagement surfaces (a, 22) of the respective first and second parts extend axially of the coupling elements. A retaining nut (3) retains the parts against each other.

Abstract: A tool or workpiece holder retention mechanism which engagably retains the holder retention portion of the holder by creating a clamping force which draws the holder retention portion into a cooperatively formed area between two retaining jaws. Two abutting surfaces, one on the holder and one on the abutting surface on the retention mechanism housing, have formed thereon cooperatively engagable surfaces at least one of which is generally spirally formed, which meshedly engage to self-center the tool holder. Preferably the cooperatively engagable surfaces are in the form of mating spiral gear teeth specifically the jaws and the holder retention portion are constructed and actuated so as to be radially freely floatable to avoid interference with the self-centering function of the mating spiral surfaces.

Abstract: A quick-change adapter which allows the precise positioning of a working member such as a tool, a workpiece or the like with respect to a machining device has a precision of one or two ten-thousandths of an inch. The adapter includes first and second holders affixed to the working member and the machining device. Each of the first and second holders includes a mating surface, configured as a helical face gear or as a cylindrical stud and recess. A shank extends from the first holder and has a V-shaped notch on which pins on the second holder abut, so as to draw the first and second holder engagement surfaces into firm abutment. The pins are preferably driven by a floating cam ring carried by the second holder, so that positioning of the holders with respect to one another is determined substantially only by the engagement surfaces. Misalignment of the holder due to movement caused by non-axial drawing on the shank is eliminated.

Abstract: A device for coupling a female member (11) to a male member (10), the male member (10) having a spigot (12) with an internal boring (13) extending in the longitudinal direction of the spigot (12). The female member (11) has a cavity (15) that receives the spigot (12) by slide-fit in a coupled state of the member (10, 11). Such devices often require several clamping elements to be activated. The present device requires only one clamping element to be activated, and has a screw assembly (14) mounted in the internal boring (13) and the screw assembly (14) includes a floating washer (34).

Abstract: A tool-and-tool holder assembly includes a tool having a tool shank; a tool holder having a receiving bore arranged for accommodating a stub of the tool shank; a clamping member disposed in the stub and being movable therein, generally perpendicularly to the shank; and two clamping screws supported in the tool holder and cooperating with the clamping member for axially tightening the shank against the tool holder. Each clamping screw has a first conical face and the clamping member has recesses each bounded by a second conical face. Upon tightening the clamping screws, the respective first and second conical faces are pressed against one another for generating an axial force component urging the shank into the receiving bore. At least one of the clamping screws has a third conical face, and the clamping member has a portion projecting over one of the recesses and having a fourth conical face.

Abstract: A tool changeover holder for machine tools has a rotationally driven spindle and a replaceable tool head that can be fixed thereto. The rotationally driven spindle has on the tool side a central journal, a chucking devoce and an annular face that surrounds this concentrically. The tool head has a central drilling to accommodate the spindle journal and an annular matching surface that surrounds the drilling concentrically. The spindle face and the matching surfaces have inversely congruent centering and torque-transmitting means that engage in each other in the chucked position. Hirth serration elements are arranged on the face of the spindle in a plurality of annular-sector shaped serration sections that lie on an annulus that is concentric with the axis of the spindle. These are separated from each other by the flat contact surface sections.

Abstract: A retention knob for reversibly locking a tool holder to a locking device in which the shaft of the retention knob has a pair of opposed recesses separated by non-recessed portions to thereby provide a significantly stronger locking engagement between the tool holder and the locking device. Also disclosed are cutting tool assemblies employing the retention knob.

Abstract: Various clamping mechanisms are known for clamping shank-like tools such as drills, milling cutters and the like. The known clamping mechanisms often require long setting times involving long idle times when changing tools, particularly on machines with several spindles. The instant disclosure teaches a clamping mechanism allowing rapid tool change on the machine spindles and having good concentricity characteristics. A bayonet catch-like locking device is used for this purpose.

Abstract: Improvements in tool holders in the field of machine tools; quick change connectors for replacing one tool holder with another in chucks mounted on rotary machine tool drive shafts and spindles; tool changing attachment permitting rapidly changing or switching one drilling, cutting or milling tool holder or collet for another involving removably engaging connectors employing mere operator hand force in effecting engaging or disengaging of the collets or tool holding adapters with the driving chuck; employing a coil compression spring as a locking element in tool holding apparatus between a chuck and a tool carrying collet, the spring captured in compressive engagement between bearing surfaces carried by the chuck and the collet, one such bearing surface provided in a nut threading on the chuck operable to hold and force the spring against a bearing surface on the collet.

Abstract: A rapid securement device for a tool or workpiece holder, comprising an elongated stem, and an elongated axle extending through the stem for axial movement relative to the stem. The stem has a head thereon, the head having a hole therethrough that registers with holes through the stem. A peg for holding a tool or a workpiece holder extends through the holes and has a flat surface that engages with a flat surface on the head. A spring urges the axle in a direction relative to the stem to engage the flat surfaces forcibly together thereby releasably to retain the peg in the holes.

Abstract: A tool holder for monitoring the service time of a tool holded on the tool holder is disclosed. A sensor and electric circuit are provided for determining whether or not the machining operation with the tool is executed. Counters are provided for counting time cumulatively during the time when the machining operation is executed, and store the cumulative time as the service time of the tool. The service time is output to a numerical control apparatus via an output device.

Abstract: Device for mounting of attachments, toolholders and tools with cone and face application, especially for machining and turning centers with automatic or manual changers of tools with tapered shank, in particular with 7/24th taper, comprising a cone (1) for introduction in the spindle, a front part (2) centered in an aperture in the cone (1) and provided with a flange for application against the face of the spindle and a gripping knob (3) for assembly of cone (1) and front part (2). The gripping knob is connected to an intermediate non-deformable connecting device having structure to allow adjustment of the length thereof. The connecting device is connected to the front part thereby to secure the front part to the cone.

Abstract: A rotationally symmetrical tool assembly includes a first component constituted by a tool holder; a second component constituted by a tool head and being removably attached to the first component such that engagement faces of the first and second components are in a contacting relationship with one another and are oriented perpendicularly to the rotary axis of the tool assembly. A fitting bore is provided in one of the components and a guide bore is provided in the other of the components. A securing pin projects from the fitting bore and extends into the guide bore for determining and maintaining a desired angular position of the second component relative to the first component.

Abstract: The present invention concerns an apparatus for locking and/or gripping modular attachments of boring heads, boring bars, intermediate members, adapters, tool holders, hydraulic punches, long tongs, or other mechanical members. The apparatus comprises one or several fastening elements (1) disposed at regular intervals over the diameter of the drive shaft (2) at a given distance from the surface of application (3) of the part to be driven or adapter (4) cooperating with the fastening elements (1). The fastening elements (1) are hemispherical headed screws, and seats (5) provided on the part to be driven or adapted (4) having a hemispherical section of greater radius than that of the screws. Driving in rotation of the drive shaft has for effect an auto-gripping of the surface (3) of the part to be driven against the application surface (6) of the drive shaft (2).

Abstract: An apparatus and tool assembly containing the same which includes a rotatable ring and a series of bearings in contact with the inner surface of the rotatable ring wherein the bearings are angled with respect to the longitudinal axis of the cutting tool assembly so that when the ring is rotated, it moves axially toward the tool holder along a helical path to thereby compress a tube containing the shaft of the cutting tool and thereby secure the cutting tool in the tool holder.

Abstract: The adaptor is to enable a cutting tool holder such as a boring bar to be mounted on a standard arbor having an internally screw-threaded boss and drive keys. The adaptor comprises a thrust ring, a retaining screw and a spacer. The thrust ring has a multiplicity of internally tapered recesses in its peripheral surface and is rotatably mounted on the arbor by the retaining screw. Rotation of the thrust ring is permitted to enable alignment of a respective recess with a respective locking screw in the cutting tool holder.

Abstract: A tool holder is enclosed in a rack which is moved by a belt for automatic tool exchange. A stopper member provided for the rack is fitted into a positioning groove formed in a flange portion of the tool holder, thereby preventing the rotation of the holder. A magnetic induction coupling apparatus is buried in the bottom of the tool holder positioning groove. A magnetic induction coupling apparatus of a reader/writer disposed at the external position is arranged so as to face the magnetic induction coupling apparatus of the tool holder. Information is written into or read out of a memory module attached in the tool holder by way of the magnetic induction coupling between both of those coupling apparatuses. The stopper member of the rack is arranged between the magnetic induction coupling apparatus of the tool holder and the magnetic induction coupling apparatus of the reader/writer and has a magnetic material to magnetically couple these coupling apparatuses.

Abstract: A pull stud detachably attached to a tool holder includes a tool data storing element for storing tool data. The arrangement being such that tool data of each tool can be stored in the tool data storing element within the pull stud attached to the tool holder holding the tool.

Abstract: A self-locking tool and socket body combination includes a tool holder with a male section which may be received in a socket in the socket body. Tool grippers of a tool loading device grip onto an annular V-groove on the tool holder and also act on an actuator. The actuator is linked to a first and second wedge surface which are moved laterally inwardly against the urging of spring means. When the tool grippers are released, the spring means urge the first and second wedge surfaces laterally outwardly into engagement with first and second wedge follower surfaces in the socket body and this automatically locks the tool holder axially within the socket body without any other manual or automatic means required to lock the tool holder within the socket.

Abstract: This invention relates to a shell-type milling cutter and a method for attaching the same wherein an area for allowing a shell-type milling cutter (1) to be in closely contact with a cutter arbour (3) is increased, whereby it makes possible a heavy-duty cutting work at a high speed which is close to that of an integral structure type milling cutter (1), besides attachment and exchange for the shell-type milling cutter can be very easily carried out.The shell-type milling cutter and the method for attaching the same according to the present invention are attained by such a manner that a fitting hole (1a) of the milling cutter (1) is formed as a tapered hole, a projection (2c) of a bush (2) is engaged with a concave groove of a clamping bolt (4), and the bush (4) is forcibly inserted into the fitting hole to secure the milling cutter (1) to the cutter arbour (3).

Abstract: The invention relates to a tool assembly and a method of assembling the tool. The assembly comprises a machine spindle component and a tool component for chip removal. The spindle component comprises a central clamp and a central recess. The tool component has a central projection and a central threaded bore in its axially rear end. The seat and the projection comprise complementary, non-circular surfaces which are brought against each other during tightening of the clamp. The tightening of the clamp is terminated by the mutual abutment of a front surface of the spindle and an end surface of the tool. The cooperating non-circular surfaces receive moment forces arising during the use of the tool.

Abstract: A quick change spindle adaptor for a power driven spindle having an axial bore and a tool holder having a shank axially projected into the spindle. A sleeve is secured upon the spindle and an outer shell is rotatably mounted upon the sleeve and retained thereon and includes a nut. A conical recess within the inner bore surface at the forward end of the spindle defines an axial bearing and receives a centering cone on the tool holder for maintaining an axial self alignment of the tool holder and spindle. Spaced threaded segments upon the tool holder are threadedly engaged by the nut for axially anchoring the tool holder upon the spindle and for biasing the centering cone into engagement with the spindle bearing.

Abstract: A reconditioned tool comprises a cylindrical insert cut from a damaged tool, such as a hog mill, with a milling face formed on one end and a transverse dovetail tenon cut in the other end. The dovetail tenon engages a transverse dovetail mortise in the end face of a cylindrical holder. A transverse slot in the holder splits the end of the holder into two axially extending end sections each of which includes one-half of the dovetail mortise. A clamping device, such as a bolt, draws the two end sections of the holder together to pull the insert firmly against the end faceof the holder through wedging action of the two halves of the dovetail mortise against the dovetail tenon. A locking pin inserted through aligned transverse grooves in the holder and insert prevents a lateral displacement of the insert relative to the holder.

Abstract: The apparatus is intended for securing a tool (3) in a holder (1), of which one (1) having a hole (2) and the other (3) having a stem (4) fitted in the hole (2), the stem surface being provided with a groove (7) having side surfaces (8, 9). The apparatus comprises a pin (10). The hole (2) and the stem (4) have bearing surfaces (12, 13). The minimum distance (1) from the bearing surface (13) of the stem (4) to the side surface (8) of the groove (7) farthest therefrom is less than the distance (L) from the bearing surface (12) of the hole (2) to the surface of the pin (10) farthest from said bearing surface (12) of the hole (2).

Abstract: In a combination including a tool head and a tool holder of a machine tool, the tool head having a shank and an outwardly radially projecting contact collar carried by the shank and the tool holder being formed to have a receiving bore which provides a counterface disposed to cooperate with the contact collar, the combination further including clamping structure for locking the tool head to the tool holder with the contact collar bearing against a selected portion of the counterface, the contact collar and the selected portion of the counterface are cylindrical and, when the contact collar is out of engagement with the counterface, the contact collar has an outer diameter which is slightly greater than the diameter of the selected portion of the counterface for effecting secure clamping of the tool head to the tool holder.