Abstract: A turning process method for processing a step-shaped workpiece includes: feeding a tool in a rotation axis direction and/or a radial direction of a workpiece while rotating the workpiece; using a tool that includes an insert with a main cutting edge having a straight portion and a machine tool having a pivot shaft of the tool in the machine side; processing a peripheral surface of the small diameter portion by turning the pivot shaft so as to have a cutting edge angle of less than 90°, the cutting edge angle having an angle between the straight portion of the main cutting edge and the rotation axis direction; and processing an end surface and a peripheral surface of the large diameter portion by turning the pivot shaft so as to have the cutting edge angle of 90° or more at a front of the large diameter portion.

Abstract: A hobbing machine is disclosed having a workpiece spindle, by means of which a workpiece can be rotated about a workpiece axis, a hobbing head, at least one chamfering device, a first slide with a first slide guide system, wherein the hobbing head is arranged on the first slide, and a rail system. The first slide, by means of its first slide guide system, is arranged in a displaceable manner on the rail system. The hobbing machine also has a second slide with a second slide guide system. The at least one chamfering device is arranged on the second slide. Also, the second slide, by means of its second slide guide system, is arranged in a displaceable manner on the rail system, such that the first slide and the second slide can be displaced on an identical portion of the rail system. Presented is a structurally simple hobbing machine by means of which a workpiece can be hobbed and chamfered in a short period of time.

Abstract: A turret tool holder includes an engagement means having engaging elements on a turret side and a support base side, a clutch member for transmitting a driving power to a turret drive section, and a moving mechanism. The moving mechanism includes a rotatably supported drive shaft, a first feed screw mechanism and a second feed screw mechanism rotatable in response to the rotational drive of the drive shaft for moving the clutch member and the engagement elements, and a coordination mechanism arranged between the drive shaft and the first feed screw mechanism or the second feed screw mechanism, for moving the engaging elements in response to the rotational drive of the drive shaft, with a feed amount smaller than the feed amount of the clutch member.

Abstract: A sliding block 31, a tool carrier 1 and a tool holder 3 are presented, providing a high-precision interface that is also adjustable. As a result, very exact positioning of the tool arranged in the tool holder 3 in relation to the tool carrier can be achieved. The repeat accuracies lie below five micrometers.

Abstract: A drive device alternatively drives a tool disk (2) of a tool turret (4) or at least one machining tool fastened to the tool disk (2) by a retaining unit (6). Two drives (8, 10) can be driven by a common drive unit (14) having a drive shaft (12). The drives (8, 10) are connectable to an output (22, 20) by a coupling unit (18) that can be controlled by at least one actuating unit (16). The output is used alternatively to drive the tool disk (2) or the machining tool. The drive unit (14) is arranged inside the tool disk (2) together with the drives (8, 10).

Abstract: The invention provides a vertical turret lathe capable of preventing an inner diameter turning tool attached to a turret tool rest from interfering with a workpiece during machining of the outer diameter of the workpiece. The vertical turret lathe comprises a work table that holds a workpiece W1 and rotates, and a working head 40 having a turret tool rest 50 and capable of moving in X-axis and Z-axis directions. A tool holder 70 for holding an inner diameter turning tool T2 via hydraulic pressure is attached to a part of the tool supporting portions 60 of the turret tool rest. The automatic tool changer apparatus 100 includes a turret-type tool magazine 120 and pistons 160 and 162, which mechanically press the pins 74 and 76 of the tool holder 70 and clamp or unclamp the tool T2.

Abstract: A turret tool holder, having structure capable of easily avoiding unnecessary free rotation of a turret, is provided. When a linearly movable shaft is moved toward a turret head section by driving a servomotor, an annular movable coupling element arranged in the turret begins to disengage from an annular fixed coupling element fixed to a support. While the movable coupling member is still engaged with the fixed coupling member, clutch teeth of a clutch member are engaged with other clutch teeth. Therefore, even when the annular movable coupling element is disengaged from the annular fixed coupling element, the turret is prevented from freely rotating by the engaged clutch teeth.

Abstract: A revolver disk (1) for a machine tool with, in the area of the radially extending bore holes (7) for the projection (9) of tool holders (5), a rotary axis of the revolver disk (1) extending parallel and penetrating bores (11) aligned perpendicular in reference to the face, by which a tool holder key (27) is guided. By displacing the tool holder key (27) against the force of a spring (17) the frontal end (25) is inserted into the clamping device in the projection (9) of the tool holder (5) and thus the tool is clamped with it.

Abstract: A combination live/dead tool holder for use on an indexing tool turret of a machine tool includes a live tool holder as well as a dead tool holder mount. The dead tool holder mount is configured to interchangeably mount to a variety of different dead tool holders. The tool holder includes a y-axis adjustment mechanism that facilitates adjustment of the position of the tool holder relative to the turret along the y axis (i.e., along a circumferential direction of the turret).

Abstract: To provide a coolant supply structure for a turret tool rest in which the central part of the intermediate shaft can be utilized effectively as a space and there is no need to allow this shaft to be hollow when a shaft such as a driving shaft is inserted. In a coolant supply structure for a turret tool rest to supply a coolant to a tool mounting part of a turret 12, which is provided in a turret tool rest 1 having a turret 12 with a tool T being mounted thereon, a hollow rotating shaft 15 for rotating the turret 12 and a hollow intermediate shaft 19 arranged within the rotating shaft 15, wherein the coolant supply structure has a cylindrical member 23 inserted into the intermediate shaft 19, and a space served as a passage 24 of the coolant is formed between the cylindrical member 23 and the intermediate shaft 19.

Abstract: A cutting tool is described comprising a cutting insert with an upper surface, a lower surface, a side surface, and a cutting blade formed at the intersection of the upper surface and the side surface, and a holder comprising an insert pocket to which the cutting insert is attached. The cutting insert is attached to the holder in such a manner that the cutting blade projects outward from the front end surface and the outer peripheral surface of the holder. The holder comprises in the outer peripheral surface on a rear end side with respect to the cutting blade a concave curve-shaped first wall surface portion that extends from the vicinity of the insert pocket toward the rear end side. The lower end of the front-end-side edge of the first wall surface portion is disposed at a lower position than the cutting blade.

Abstract: A tool-holding device for a lathe is provided including a lathe-attachment portion, with a base sized and shaped for placement on a lathe and attaching means for attaching the base to the lathe. The lathe-attachment portion also has a circular-perimeter, angled mounting apparatus integral with the base and having equal-sized wedge-shaped, double sloped clamping portions and a partly threaded central locking base-bore. Attached to the lathe-attachment portion is a frusto-conical multiple-tool tool-holder having a lower surface with an equal number of equal-sized wedge-shaped, double sloped clamping surfaces to mate with the clamping portions of the base. The upper surface of the tool-holder has insert pockets for attachment of tools. A central bore extends through the tool-holder for locking the tool-holding device to a lathe or other machine.

Abstract: The present invention provides a tool post of a machine tool capable of enhancing the accuracy of positioning a tool. A positioning key 20 is fixed to an attached surface 10c formed on a tool holder 10, and a positioning block 21 fitting to the positioning key 20 is fixed to a holder attaching surface 11c formed on an outer peripheral surface 11a of a turret 11, in which the positioning key 20 is elastically deformed when it is fitted to the positioning block 21, and thereby brought into close contact with the positioning block 21.

Abstract: Methods of fly-cutting a workpiece are disclosed, and in methods in which the position of a fly-cutting head or its associated cutting element is known as a function of time. Also disclosed are methods of forming features, such as grooves or groove segments, in a workpiece such as a cylindrical roll. The features may be provided according to one or more disclosed patterns. Articles made using tools machined in the manner described are also provided, such as polymeric film or sheeting that exhibit certain beneficial properties.

Abstract: A tool holder includes a hollow taper shank chucking device having a center axis, a chucking device, a tension rod which cooperates with the chucking device and an actuating unit by means of which the tension rod may be actuated, i.e., displaced. The actuating unit has an actuating element which is movable at an angle relative to the center axis and which includes at least one actuating part. The angle may be 90°. The tension rod is provided with at least one engagement part. The actuating part and engagement part form a wedge mechanism which is used to convert a radial motion of the actuating element, i.e., a displacement perpendicular to the center axis, into an axial displacement of the tension rod in the direction of the center axis.

Abstract: A carriage is moved in a direction including a Y axis component in order to move a turning process tool that is attached to a tool spindle along a horizontal line that is perpendicular to a Z axis, and thus, a turning process is carried out on a workpiece which is attached to a workpiece spindle.

Abstract: A tool-holding device for a lathe is provided including a lathe-attachment portion, with a base sized and shaped for placement on a lathe and attaching means for attaching the base to the lathe. The lathe-attachment portion also has a circular-perimeter, angled mounting apparatus integral with the base and having equal-sized wedge-shaped, double sloped clamping portions and a partly threaded central locking base-bore. Attached to the lathe-attachment portion is a frusto-conical multiple-tool tool-holder having a lower surface with an equal number of equal-sized wedge-shaped, double sloped clamping surfaces to mate with the clamping portions of the base. The upper surface of the tool-holder has insert pockets for attachment of tools. A central bore extends through the tool-holder for locking the tool-holding device to a lathe or other machine.

Abstract: A quick change tool holder having a base member, a body, a quick change head member, and a cutting tool cartridge. The base member includes an upper surface, bottom surface, and mating surface and is adapted to removably mount to an associated cutting machine carriage. The body includes an end wall and an inner surface, where the end wall includes a dovetail portion. The body is adapted to engage the base member in an interlocking fashion. The quick change head includes a top surface, a bottom surface, an interface wall having a channel disposed therein, and an outer wall having a plurality of longitudinal grooves, wherein said channel is adapted to receive said dovetail portion. The cutting tool cartridge is adapted to engage the longitudinal grooves of the quick change head.

Abstract: Turrets (11, 12), which can rotate about a common axis (y-y) and on the outer peripheral surfaces of which a plurality of tools (15) are radially installed, are disposed along the axis (y-y) in a turret housing (100). Respective turrets (11, 12) can be dividedly rotated by separate turret driving motors (13, 14).

Abstract: A method is provided for fabricating a seal ring. The method includes positioning a mount assembly adjacent to at least one of an inner diameter and an outer diameter of an annular seal ring, and securing the annular seal ring to the mounting assembly. The method also includes forming at least one of an admission side hook and a steam joint side hook in the annular seal ring.

Abstract: A tool holding device is disposed between a headstock unit and a tailstock unit of a five-axis lathe, and includes a saddle driven to move longitudinally, a cross-slide riding on the saddle and driven to move transversely, a turntable platform disposed on a base mount that is disposed on the cross-slide and driven to revolve about an upright axis, and a tool post mounted on a base rest that is disposed on the turntable platform and driven to move uprightly. An indexable turret is disposed on the tool post for holding tool bits such that the five-axis lathe can perform movements about five axes to machine a workpiece so as to obtain a complicated geometric shape, thereby reducing setup time and errors and increasing production.

Abstract: To provide a coolant supply structure for a turret tool rest in which the central part of the intermediate shaft can be utilized effectively as a space and there is no need to allow this shaft to be hollow when a shaft such as a driving shaft is inserted. In a coolant supply structure for a turret tool rest to supply a coolant to a tool mounting part of a turret 12, which is provided in a turret tool rest 1 having a turret 12 with a tool T being mounted thereon, a hollow rotating shaft 15 for rotating the turret 12 and a hollow intermediate shaft 19 arranged within the rotating shaft 15, wherein the coolant supply structure has a cylindrical member 23 inserted into the intermediate shaft 19, and a space served as a passage 24 of the coolant is formed between the cylindrical member 23 and the intermediate shaft 19.

Abstract: There is provided an automatic tool changer which, in a precision roll turning lathe which feeds a tool post at a high speed, can automatically change a tool, such as a cutting tool, without stopping the machine, thereby enabling highly efficient ultra-Precision machining of a roll mold for molding of a large-sized plastic sheet.

Abstract: There is provided a precision roll turning lathe which can machine with high precision a three-dimensional pattern of three-sided pyramids or four-sided pyramids in the surface of a roll.

Abstract: A roll turning lathe is provided herein which can not only machine with high precision circumferential transverse grooves in the peripheral surface of a roll but can also machine with high precision longitudinal grooves in the peripheral surface. The precision roll turning lathe includes a fly cutter spindle device and a tool post having a plurality of cutting tools that are mounted on a tool swivel. By selectively using the tool post and the fly cutter spindle device, high-precision machining of transverse grooves and longitudinal grooves on a roll-shaped workpiece.

Abstract: A tool revolver, in particular for a machine tool, includes a tool disk (1) rotatable about a revolver axis and provided with a plurality of tool stations distributed along the disk circumference and movable to an operation position by the disk (1) rotation. At least one part of the tool stations (13) has a reception area (25) for receiving a tool holder (3). A fixing device is used for fixing a corresponding tool holder (3) at a defined position in the reception area (25). The interaction between an elastic adjusting body (31) protruding perpendicularly to the reception area (25) and used in the form of an orientation element for positioning and adjusting surfaces (41, 43) deepened into a base surface (7) of the tool holder (3) enables the tool holder to take an adjustment position when a screw fitting is fastened.

Abstract: A turret tool holder, having means capable of easily avoiding unnecessary free rotation of a turret, is provided. When a linearly movable shaft is moved toward a turret head section by driving a servomotor, an annular movable coupling element arranged in the turret begins to disengage from an annular fixed coupling element fixed to a support. While the movable coupling member is still engaged with the fixed coupling member, clutch teeth of a clutch member are engaged with other clutch teeth. Therefore, even when the annular movable coupling element is disengaged from the annular fixed coupling element, the turret is prevented from freely rotating by the engaged clutch teeth.

Abstract: A combination live/dead tool holder for use on an indexing tool turret of a machine tool includes a live tool holder as well as a dead tool holder mount. The dead tool holder mount is configured to interchangeably mount to a variety of different dead tool holders. The tool holder includes a y-axis adjustment mechanism that facilitates adjustment of the position of the tool holder relative to the turret along the y axis (i.e., along a circumferential direction of the turret).

Abstract: A turret tool rest is provided with a tool rest body, which is rotatable around the vertical axis, on a lower saddle. A turret is provided on a side surface of the tool rest body, and an anti-vibration mechanism is provided on a side surface that is adjacent to the side surface at a right angle. Indexing can be performed by selecting from the turret and the anti-vibration mechanism by rotation of the tool rest body.

Abstract: The present invention provides a precision roll turning lathe which can form a pattern including three-dimensionally shaped portions, such as three-sided pyramids, on the surface of a roll, with high accuracy. Specifically, a tool post is provided with a tool turning axis (A axis) which is used to turn a tool such that, when forming a spiral groove cut through the roll, a cutting face of a tip of the tool is oriented perpendicular to a direction along which the spiral groove extends.

Abstract: A tool holding device is disposed between a headstock unit and a tailstock unit of a five-axis lathe, and includes a saddle driven to move longitudinally, a cross-slide riding on the saddle and driven to move transversely, a turntable platform disposed on a base mount that is disposed on the cross-slide and driven to revolve about an upright axis, and a tool post mounted on a base rest that is disposed on the turntable platform and driven to move uprightly. An indexable turret is disposed on the tool post for holding tool bits such that the five-axis lathe can perform movements about five axes to machine a workpiece so as to obtain a complicated geometric shape, thereby reducing setup time and errors and increasing production.

Abstract: The present invention provides a tool post of a machine tool capable of enhancing the accuracy of positioning a tool. A positioning key 20 is fixed to an attached surface 10c formed on a tool holder 10, and a positioning block 21 fitting to the positioning key 20 is fixed to a holder attaching surface 11c formed on an outer peripheral surface 11a of a turret 11, in which the positioning key 20 is elastically deformed when it is fitted to the positioning block 21, and thereby brought into close contact with the positioning block 21.

Abstract: Turrets (11, 12), which can rotate about a common axis (y-y) and on the outer peripheral surfaces of which a plurality of tools (15) are radially installed, are disposed along the axis (y-y) in a turret housing (100). Respective turrets (11, 12) can be dividedly rotated by separate turret driving motors (13, 14).

Abstract: A turret lathe includes a bed having a chip pan, parallel bed ways, a first motor on the bed, a sliding carriage on the bed ways driven by the first motor for translating the carriage in a first direction, the carriage having a gable guard above the bed ways, and a second motor; a turret assembly slidably mounted on the carriage and driven by the second motor for translating the turret assembly in a second direction perpendicular to the first direction; an L-shaped headstock including a first chuck and a third motor at an open end of the horizontal portion; and a tailstock including a second chuck aligned with the first chuck, a second slide, a threaded shaft through the second slide to rotatably connect to the third motor, and two parallel racks between the second slide and the horizontal portion of the headstock.

Abstract: A tool holder positioning device includes: a plurality of protruded portions or a plurality of recessed portions formed to a seating surface of a tool rest; and a plurality of recessed portions or a plurality of protruded portions formed to a coupling surface of a tool holder so as to correspond, respectively, to a plurality of protruded portions or a plurality of recessed portions formed to the seating surface of the tool rest, when the seating surface and the coupling surface are contacted. At least one of the protruded portions and at least one of the recessed portions are disposed on an intersecting axis included in the seating surface, and the recessed portions and the protruded portions to be fitted to the plurality of protruded portions and the plurality of recessed portions are disposed on an intersecting axis included in the coupling surface.

Abstract: Disclosed are a tool indexer assembly, a computer numerically controlled machine that includes such tool indexer assembly, and associated methods. The assembly in one embodiment includes a turret and an indexer, the indexer including a portion that is movable with respect to the turret and that includes plural tool station configured to receive plural tool structures. The tool indexer is disposed on a facet of the turret, and, in some embodiments includes a table that is rotatable about an axis that is generally orthogonal to the axis of rotation of the turret. In another embodiment, a tool indexer includes a clamping mechanism having a source of pressurized fluid and a piston that is hydraulically actuated by the pressurized fluid and movable to a clamping position. The assembly further includes a conduit for delivery of the pressurized fluid proximal the tool structure as coolant fluid.

Abstract: The invention relates to a tool revolver, in particular for a machine tool, comprising a tool disk (1) which is rotatable about a revolver axis and provided with a plurality of tool stations which are distributed along the disk circumference and can be moved to an operation position by the disk (1) rotation, wherein at least one part of said tool stations (13) comprises a reception area (25) for receiving a tool holder (3) and a fixing device is used for fixing a corresponding tool holder (3) at a defined position in the reception area (25), respectively. The interaction between an elastic adjusting body (31) which is protruded perpendicularly to the reception area (25) and is used in the form of an orientation element for positioning, and adjusting surfaces (41, 43) deepened into a base surface (7) of the tool holder (3) enables the tool holder to take an adjustment position when a screw fitting is fastened.

Abstract: A rotary tool-equipped tool rest is provided, including a movable member made to move frontwardly when a turret is clamped with respect to a non-swiveling housing after swiveling and indexing. Then, a phase determining pin provided in the turret is made to project and engage with the non-swiveling housing. Further, a coupling mechanism to clamp the turret with respect to the non-swiveling housing has three coupling members.

Abstract: A toolholder with a controllable critical angle, such as a lead, trailing, rake or clearance angles, includes a tool spindle for retaining the toolholder in a tool rest of a machine tool. The machine tool includes at least one linear axis, for example, three mutually perpendicular axes, a rotary axis and a rotation axis. The rotary axis and/or rotation axis is controllable to move to a specified position in synchronization with a movement of one of the linear axes. An adaptor supports a cutting tool that is retained in the adaptor by a clamp. The cutting tool defines a critical angle, such as a lead angle, a trailing angle, a rake angle and a flank clearance angle, wherein the critical angle is corrected as a vector of movement of at least one of the linear axis is changed. In addition, the cutting tool can be positioned on opposite side of a centerline of rotation of the workpiece to effectively double the life of the cutting tool. A method of controlling a toolholder is also disclosed.

Abstract: A dual disc type of tool turret device is powered by means of single main power source, which also serves to power the spindle of the machine; the turret device includes an inner and outer tool turrets; when power is transmitted from the main power source through a transmission element, a piston clutching piece, and rotary shaft (A), the inner turret will be rotated to carry out a tool-choosing operation; when power is further passed on to rotary shaft (B) through rotary shaft (A), the inner turret will be rotated to carry out a tool-choosing operation; after the tool-choosing action, power is supplied to the spindle of the machine in order for the machine to carry out a machining operation.

Abstract: A turret tool rest 6 is provided with a tool rest body 10, which is rotatable around the vertical axis, on a lower saddle 7. A turret 13 is provided on a side surface 11 of the tool rest body 10, and an anti-vibration mechanism 15 is provided on a side surface 12 that is adjacent to the side surface 11 at a right angle. Indexing can be performed by selecting from the turret 13 and the anti-vibration mechanism 15 by rotation of the tool rest body 10.

Abstract: A telescopic safety shield device includes a carrier movably engaged onto a platform and having one or more guideways tilted relative to the platform, a tool rest movably engaged onto the guideways and moveable inclinedly relative to the carrier and the platform, and a telescopic shielding device having two or more casing members coupled between the platform and the tool rest for shielding the area between the platform and the tool rest, the casing members are pivotally coupled to the platform and the tool rest for allowing the casing members to be pivoted relative to the platform and the tool rest respectively and for preventing dirt or contaminant from entering into the areas between the platform and the tool rest.

Abstract: A rotational power servo toolpost includes a plurality of rotational tool holders, which can freely rotate 360 degrees, to cut a workpiece from various angles. The rotational power servo toolpost has a turret base, a turret, tool holders mounted on a side surface of the turret and having a variety of needed tools, a tool-holder-rotating device, and a tool-rotating device. When the tool holder with the needed tool rotates along with the turret to the preset area, a servo motor of the tool-holder-rotating device drives the related members to freely rotate the tool holder around 360 degrees according to the machining requirements. The tool-driving device then drives the tool, thereby cutting the workpiece from various angles.

Abstract: A turret includes a central shaft, a piston sleeve positioned around the central shaft and having moving sticks thereon, a push rod, an actuating seat, and internal and external turrets; the piston sleeve is left and right movable by a power source; the moving sticks are passed through a ringed sleeve, which props a push rod passed through a fixed clutch claw, and facing the actuating seat; the actuating seat includes a rotary shaft, a pivotal shaft, and a toothed ring seat; the piston sleeve can be moved such that the moving sticks and the push rod move forwards, and the rotary shaft engages the toothed ring seat for a tool of a straight tool seat to function; alternatively the piston sleeve can be moved such that the moving sticks and the push rod move backwards, and the rotary shaft disengages the toothed ring seat for allowing replacement of the toothed ring seat.

Abstract: An indexible turning tool for chip forming machining, includes a holder equipped with insert pockets receiving replaceable inserts, as well as a securing portion intended to be received in a tool machine. At least one of the replaceable inserts has a main plane that extends laterally in relation to the tool's axial direction.

Abstract: A turret body is provided with a tool spindle for detachably attaching a complex tool so as to be freely rotated with an axial center as its center. The turret body is provided with indexing means for indexing the tool spindle, and clamping means for clamping the tool spindle at an indexed position indexed by the indexing means. The turret body has a function for indexing the tool spindle for attaching the complex tool thereto and a function for clamping, thereby using the complex tool in a turret lathe.

Abstract: There is provided a tool holder capable of attaching a plurality of tools to one tool holder, and easily adjusting these tools in a positional relation suitable for work machining. The tool holder comprises a holder body 201 attached to a tool rest 160, a plurality of surfaces 202 and 203 formed around the holder body 201, holders 210 and 220 attached to the surfaces 202 and 203 and having tools for machining the work attached thereto, toothed portions 208 and 209 of tooth-shaped rows formed in a predetermined direction on the surfaces 202 and 203, engaging portions 211 and 221 formed on the surfaces of the holders attached to the surfaces 202 and 203, and engaged with the toothed portions to position the holders in predetermined positions of the surfaces 202 and 203, and attaching means 240 and 250 for attaching the holders to the holder body in engaging states between the toothed portions and the engaging portions.

Abstract: An indexible turning tool for chip forming machining, includes a holder equipped with insert pockets receiving replaceable inserts, as well as a securing portion intended to be received in a tool machine. At least one of the replaceable inserts has a main plane that extends laterally in relation to the tool's axial direction.

Abstract: A cutter holder for CNC lathe is disclosed to include a bottom holder block, which is affixed to the frame of a CNC lathe with screws and has a positioning groove with a middle semispherical recess for holding a barrel that holds a tool shank with a front chuck for holding a cutting tool, and a top holding down block, which is detachably affixed to the bottom holder block with screws to hold down the barrel and has a semispherical bottom recess fitting the spherical middle flank portion of the barrel corresponding to the middle semispherical recess of the bottom holder block.

Abstract: A tool holder simultaneously carries at least two diametrically arranged tool heads, each tool head carrying cutting inserts for chip removing machining. The tool holder includes an adaptor connected to a coupling. The adaptor has at least two diametrically opposite side surfaces which-diverge away from the coupling. The side surfaces have seats in order to replaceably receive respective tool heads. A line which lies in both a first basal plane and in one of the side surfaces forms an angle in the interval 1°–15° with a longitudinal center line of the tool holder.