Abstract:
A tool chucking device, especially an oscillation tool chucking device, includes at least one chucking unit which has at least one pin-type chucking element for clamping a treatment tool in an axial direction and at least one grip head arranged on the chucking element. The tool chucking device further includes at least one movement conversion unit which is designed to displace at least the grip head at least substantially along the axial direction into at least one direction different from the axial direction depending on the movement of the chucking element.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2011/074105, filed on Dec. 27, 2011, which claims the benefit of priority to Ser. No. DE 10 2011 003 103.0, filed on Jan. 25, 2011 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     There are already known tool clamping devices, in particular oscillating-tool clamping devices, that have a clamping unit. The clamping unit in these cases has a pin-shaped clamping element for chucking a working tool in an axial direction, and has a clamping head disposed on the clamping element. 
     SUMMARY 
     The disclosure is based on a tool clamping device, in particular an oscillating-tool clamping device, comprising at least one clamping unit that has at least one pin-shaped clamping element for chucking a working tool in an axial direction, and has at least one clamping head disposed on the clamping element. 
     It is proposed that the tool clamping device has at least one motion conversion unit, which is provided to move at least the clamping head, in dependence on a motion of the clamping element at least substantially along the axial direction, in at least one direction differing from the axial direction. In this context, the term “provided” is to be defined as specially equipped and/or specially configured. A “clamping unit” is to be understood here to mean, in particular, a unit that secures a working tool along the axial direction by means of a positive closure and/or by means of a non-positive closure, in particular on a tool receiver of a portable power tool. Preferably, when the clamping unit is in a clamping mode, a clamping force acts upon the working tool, along the axial direction. A “pin-shaped clamping element” is to be understood here to mean, in particular, a clamping element that, when in a mounted state, has a longitudinal extent, along the axial direction, that is greater than a transverse extent of the clamping element along a direction running perpendicularly in relation to the axial direction. In particular, the longitudinal extent is more than twice as great as the transverse extent of the clamping element, preferably more than four times as great, and particularly preferably more than six times as great. Preferably, the pin-shaped clamping element is realized at least partially as a hollow body. Particularly preferably, the clamping element has at least two partial regions, realized as limbs, which are disposed at a distance apart, relative to each other, at least partially, along a direction running at least substantially perpendicularly in relation to the axial direction. Preferably, the clamping element is disposed in a captive manner in a hollow shaft of the portable power tool. The term “axial direction” is intended here to define, in particular, a direction that preferably runs at least substantially parallelwise in relation to a swivel axis and/or a rotation axis of a drive shaft and/or spindle of a portable power tool that is provided to drive the working tool. “Substantially parallel” is to be understood here to mean, in particular, an alignment of a direction relative to a reference direction, in particular in one plane, the direction deviating from the reference direction by, in particular, less than 8°, advantageously less than 5°, and particularly advantageously less than 2°. 
     A “clamping head” is to be understood here to mean, in particular, an element having at least one clamping face that, for the purpose of chucking the working tool in the axial direction, bears against at least a partial surface of the working tool and acts with a clamping force upon the working tool along the axial direction. The term “motion conversion unit” is intended here to define, in particular, a unit comprising a mechanism by means of which a motion of a first element, in particular a translational motion of the first element, can be converted into a motion of a further element, in particular into a swivel motion and/or translational motion of the further element. Preferably, a translational motion of the clamping element is converted into a swivel motion and/or into a translational motion of the clamping head by means of the motion conversion unit. Particularly preferably, the clamping head is moved, by means of the motion conversion unit, at least substantially along a main motion component that runs at least substantially perpendicularly in relation to the axial direction. The expression “substantially perpendicularly” is intended here to define, in particular, an alignment of a direction relative to a reference direction, the direction and the reference direction, in particular as viewed in one plane, enclosing an angle of 90°, and the angle having a maximum deviation of, in particular, less than 8°, advantageously less than 5°, and particularly advantageously less than 2°. “Substantially along” is to be understood here to mean, in particular, a course of a direction along a reference direction, the direction deviating from the reference direction by, in particular, less than 8°, advantageously less than 5°, and particularly advantageously less than 2°. The design of the tool clamping device according to the disclosure makes it possible, advantageously, to achieve a clamping operation that is easy to perform. Further, through simple design means, it is possible to achieve chucking of the working tool on a tool receiver of the portable power tool, in particular a portable power tool having a spindle that can be driven in an oscillatory manner. 
     Further, it is proposed that the motion conversion unit has at least one motion conversion element, which is provided to move the clamping head in at least one direction differing from the axial direction, for the purpose of achieving an axial overlap of the clamping head and the working tool, at least when the clamping unit is in a clamping mode. A “clamping mode” is to be understood here to mean, in particular, a state of the clamping unit in which the working tool has been secured by means of the clamping element and/or the clamping head. In particular, in the clamping mode, the working tool is secured to a tool receiver of a portable power tool by means of the clamping unit, along the axial direction and/or along the radial direction, for the purpose of performing work on workpieces. Particularly preferably in this case, a clamping force is applied to the working tool along the axial direction. A “radial direction” is intended here to mean, in particular, a direction running at least substantially perpendicularly in relation to the axial direction. Preferably, the motion conversion element is realized such that it is separate from the clamping element and/or the clamping head. The expression “axial overlap” is intended here to define, in particular, an overlap, in particular of partial regions, of at least two components along the axial direction; in particular, a straight line intersects the two components along the axial direction. Preferably, when in the clamping mode, at least one clamping face of the clamping head overlaps at least one partial region of the working tool along the axial direction. Particularly preferably, when the clamping head is in a mounted state, the overlap can be temporarily removed, in particular for the purpose of changing the working tool and/or for the purpose of altering a position, in particular altering an angular position, of the working tool. Advantageously, it is possible to achieve chucking and/or release of the working tool without the use of tools. Advantageously, therefore, it is possible to dispense with an additional tool for chucking and/or release operations. Moreover, the working tool can be mounted and/or chucked on the tool receiver of the portable power tool without removal and/or demounting of the clamping element. 
     Advantageously, the motion conversion element is realized as stud. A “stud” is to be understood here to mean, in particular, an element having a longitudinal extent greater than a transverse extent that runs perpendicularly in relation to the longitudinal extent. Preferably, the stud is realized in the form of a cylinder. Particularly preferably, the stud is realized so as to be rotationally symmetrical about at least one axis. Preferably, the stud is composed of a solid material. It is also conceivable, however, for the motion conversion element to be of a different design, considered appropriate by persons skilled in the art. A motion conversion element can be achieved through simple design means. Moreover, particularly advantageously, in particular in the case of the stud being designed as a cylindrical stud, at least a partial region of the clamping head can slide on the motion conversion element in the case of a motion of the clamping head, as a result of a motion of the clamping element. Advantageously, it is possible to achieve a tool clamping device according to the disclosure that is sparing of material. Advantageously, therefore, it is possible to achieve a long service life of the tool clamping device according to the disclosure. 
     Preferably, the clamping head is disposed in a resilient manner on the clamping element. The expression “disposed in a resilient manner” is intended here to define, in particular, a non-jointed, spring-elastic coupling of an element to a further element, a relative motion of the elements being possible, without a joint and as a result of an elastic deflection of the elements relative to each other. Preferably, the resilient disposition is realized through special material properties and/or a special geometry of the clamping head and of the clamping element. In particular, the clamping head can be deflected, relative to the clamping element, by more than 1 mm, preferably more than 2 mm, and particularly preferably more than 5 mm. Advantageously, simple design means make it possible for the clamping head to be movable relative to the clamping element. 
     In addition, it is proposed that the motion conversion unit has at least one cam member, in which the motion conversion element engages, at least partially. A “cam member” is to be understood here to mean, in particular, an element of a cam mechanism. The term “cam mechanism” is intended here to define, in particular, a mechanism that, as a result of a motion of the cam member and as a result of acting in combination with the motion conversion element, operates a component that, as a result, executes a motion defined by the combined action of the cam member and the motion conversion element. A motion of one element can be converted into a motion of a further element through simple design means. Advantageously, therefore, it is possible to achieve a tool clamping device that is easy to operate. 
     Preferably, the cam member is disposed on the clamping element. Particularly preferably, the cam member is realized as a slot. The slot is constituted, in particular, by a material cut-out in the clamping element. Preferably, in comparison with a region of the clamping element that adjoins the cam member, the cam member is of a lesser material thickness, in particular a material thickness of 0 mm. It is also conceivable, however, for at least two ribs to be disposed on an outer face of the clamping element, the motion conversion element engaging, at least partially, in the ribs. In particular, in this case, the at least two ribs can extend, starting from the outer face, at least substantially perpendicularly in a direction oriented away from the clamping element, such that the at least two ribs can constitute a guide for the motion conversion element. Other designs for constituting a cam member that are considered appropriate by persons skilled in the art are likewise conceivable. The motion conversion element preferably extends through the cam member, in particular along a direction running at least substantially perpendicularly in relation to the axial direction. The term “extend through” is to be understood here to mean, in particular, that the motion conversion element has a main extent along a radial direction, which runs at least substantially perpendicularly in relation to the axial direction and which is greater than an extent of the cam member along the radial direction running at least substantially perpendicularly in relation to the axial direction. Advantageously, a saving of structural space can be achieved. As a consequence, advantageously, a compact tool clamping device can be achieved. 
     Further, it is proposed that at least the clamping head has at least two partial regions that are movable relative to each other. Preferably, the two partial regions are movable relative to each other because of an elastic material property and/or a special geometry of the clamping head. Preferably, the two partial regions are movable relative to each other as a result of the clamping head being resiliently coupled to the clamping element. In an alternative design of the tool clamping device according to the disclosure, the clamping element likewise has two partial regions that are movable in relation to each other. In this case, the partial regions of the clamping element are mounted such that they can be swiveled relative to each other. Particularly preferably in this case, a partial region of the clamping head is realized, respectively, so as to be integral with a partial region of the clamping element. Advantageously, symmetrical chucking of the working tool can be achieved, in particular on a tool receiver of a portable power tool. 
     Advantageously, the motion conversion unit is realized as an expansion unit, which is provided to move at least two partial regions of the clamping head, which are movable relative to each other, in oppositely oriented directions relative to each other, in at least one operating mode of the clamping unit. An “expansion unit” is to be understood here to mean, in particular, a unit provided to move at least two partial regions of a component relative to each other. Preferably, the partial regions of the clamping head and/or of the clamping element are moved along a main motion component, which runs at least substantially perpendicularly in relation to the axial direction. Through simple design means, it is possible to achieve a motion of two partial regions of the clamping head and/or of the clamping element. 
     Preferably, the clamping head is realized so as to be integral with the clamping element. “Integral with” is to be understood here to mean, in particular, connected at least in a materially bonded manner, for example by a welding process, an adhesive bonding process, an injection process and/or by another process considered appropriate by persons skilled in the art, and/or, advantageously, formed in one piece, such as, for example, by being produced from a casting and/or by being produced in a single- or multi-component injection process and, advantageously, from a single blank. Advantageously, saving in assembly work can be achieved. 
     Further, the disclosure is based on a portable power tool, in particular a portable power tool having a spindle that can be driven in an oscillatory manner, having at least one tool clamping device according to the disclosure. A “portable power tool” is to be understood here to be, in particular, a power tool for working of workpieces, in particular a handheld power tool, that can be transported by an operator without a transport machine. The portable power tool has, in particular, a mass of less than 40 kg, preferably less than 10 kg, and particularly preferably less than 5 kg. Advantageously, it is possible to achieve a high degree of operating comfort for an operator of the power tool. 
     The tool clamping device according to the disclosure is not intended in this case to be limited to the application and embodiment described above. In particular, the tool clamping device according to the disclosure can have individual elements, components and units that differ in number from a number stated herein, in order to fulfill a principle of function described herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages are given by the following description of the drawing. The drawing shows exemplary embodiments of the disclosure. The drawing, the description and the claims contain numerous features in combination. Persons skilled in the art will also expediently consider the features individually and combine them to create appropriate further combinations. 
       In the drawing: 
         FIG. 1  shows a power tool according to the disclosure having a tool clamping device according to the disclosure, in a schematic representation, 
         FIG. 2  shows a detail view of the tool clamping device according to the disclosure, in a tool changing mode of a clamping unit of the tool clamping device according to the disclosure, in a schematic representation, 
         FIG. 3  shows a detail view of the tool clamping device according to the disclosure, in a clamping mode of the clamping unit, in a schematic representation, 
         FIG. 4  shows a detail view of an alternative tool clamping device according to the disclosure, in a tool changing mode of a clamping unit of the alternative tool clamping device according to the disclosure, in a schematic representation, 
         FIG. 5  shows a detail view of a clamping head of a clamping unit of the alternative tool clamping device according to the disclosure, in a tool changing mode of the clamping unit, in a schematic representation, 
         FIG. 6  shows a detail view of the alternative tool clamping device according to the disclosure from  FIG. 4 , in a clamping mode of the clamping unit, in a schematic representation, and 
         FIG. 7  shows a detail view of the clamping head of the clamping unit of the alternative tool clamping device according to the disclosure, in a clamping mode of the clamping unit, in a schematic representation. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows an electrically operated, portable power tool  38   a , having a tool clamping device  10   a . The portable power tool  38   a  comprises a power-tool housing  42   a , which encloses an electric motor unit  44   a , a transmission unit  46   a  and an output unit  48   a  of the portable power tool  38   a . The power tool housing  42   a  in this case comprises two housing half shells  50   a ,  52   a , which are separably connected to each other along a plane that is oriented parallel to an axial direction  18   a  and an axial direction  18   b  which is opposite the axial direction  18   a . It is also conceivable, however, for the power tool housing  42   a  to have two or more pot-shaped housing parts that can be separably connected to each other. The axial direction  18   a  and the axial direction  18   b  run along and/or parallelwise in relation to a rotation axis  54   a  of a hollow shaft  56   a  of the output unit  48   a  that is realized as a spindle  40   a  ( FIG. 2 ). The hollow shaft  56   a  is provided to drive a working tool  16   a  in an oscillatory manner, when in a mounted state. Oscillatory driving of the working tool  16   a  in this case is effected in a manner already known to persons skilled in the art, such as, for example, by means of a peg (not represented in greater detail here) of the transmission unit  46   a , which is disposed eccentrically on a drive shaft of the electric motor unit  44   a  and which, by means of a rocker and an oscillating sleeve (not represented in greater detail here) of the transmission unit  46   a , drives the hollow shaft  56   a  when the portable power tool  38   a  is in operation. The hollow shaft  56   a , realized as a spindle  40   a , can therefore be driven in an oscillatory manner. The working tool  16   a  can be fastened to a tool receiver  58   a  of the output unit  48   a , for the purpose of performing work on workpieces by removal of material. The tool receiver  58   a  is connected to the hollow shaft  56   a  in a rotationally fixed manner by means of a positive and/or non-positive connection. It is also conceivable, however, for the tool receiver  58   a  to be realized so as to be integral with the hollow shaft  56   a . A pivoting motion of the hollow shaft  56   a  can be transmitted to the tool receiver  58   a.    
       FIG. 2  shows a detail view of the tool clamping device  10   a  when in a tool changing mode, in which an operator can mount the working tool  16   a  on the tool receiver  58   a  and/or can alter a position of the working tool  16   a  relative to the tool receiver  58   a , along a circumferential direction  62   a . For the purpose of fastening the working tool  16   a  to the tool receiver  58   a  in a rotationally fixed manner, the working tool  16   a  has driving recesses  60   a , which are disposed in a circular ring along the circumferential direction  62   a , uniformly distributed on the working tool  16   a . The working tool  16   a  has a total of 12 driving recesses  60   a  (not all represented here), disposed in a uniformly distributed manner in a circular ring along the circumferential direction  62   a . It is also conceivable, however, for the working tool  16   a  to have a number of driving recesses  60   a  other than 12. The circumferential direction  62   a  runs in a plane that extends perpendicularly in relation to the axial directions  18   a  and  18   b . The tool receiver  58   a  has a clamping surface  116  with hump-type protrusions  64   a , which corresponds to the driving recesses  60   a  and which extend from the clamping surface  116  through the driving recesses  60   a , along the axial direction  18   b , when the working tool  16   a  is in a mounted state on the tool receiver  58   a . The hump-type protrusions  64   a  in this case are realized as latching cams  66   a . The tool receiver  58   a  has a total of 12 latching cams  66   a  (not all represented here), which are disposed in a uniformly distributed manner in a circular ring along the circumferential direction  62   a . It is also conceivable, however, for the tool receiver  58   a  to have a number of latching cams  66   a  other than 12. 
     The tool clamping device  10   a  comprises a clamping unit  12   a . The clamping unit  12   a  has a pin-shaped clamping element  14   a  for chucking the working tool  16   a  ( FIG. 3 ). The clamping element  14   a  is disposed in a movable manner in the hollow shaft  56   a . The clamping element  14   a  in this case extends, along the axial direction  18   b , through the hollow shaft  56   a . When in a mounted state, therefore, the clamping element  14   a  is disposed in the hollow shaft  56   a . Furthermore, the clamping element  14   a  has two limbs  68   a ,  70   a , which extend at least substantially along the axial direction  18   b  when the clamping element  14   a  is in a mounted state. The limbs  68   a ,  70   a  are realized so as to be integral with the clamping element  14   a . Furthermore, the limbs  68   a ,  70   a  have little thickness of material, as viewed along a direction running perpendicularly in relation to the axial direction  18   b , in order to enable deflection of the limbs  68   a ,  70   a . Owing to material properties and/or a geometric shape of the limbs  68   a ,  70   a , therefore, the limbs  68   a ,  70   a  are disposed on the clamping element  14   a  so as to be movable relative to each other. The limbs  68   a ,  70   a  in this case are disposed in a resilient manner on the clamping element  14   a . Furthermore, the limbs  68   a ,  70   a  are disposed at a distance relative to each other along the direction running perpendicularly in relation to the axial direction  18   a . Owing to their resilient disposition on the clamping element  14   a  and the relative distance in relation to each other along the direction running perpendicularly in relation to the axial direction  18   b , the limbs  68   a ,  70   a  can move relative to each other. 
     Further, the clamping unit  12   a  has a clamping head  20   a , disposed on the clamping element  14   a . The clamping head  20   a  in this case is realized so as to be integral with the clamping element  14   a . The clamping head  20   a  has two partial regions  30   a ,  32   a , which are movable relative to each other. One of the partial regions  30   a ,  32   a , respectively, is disposed on a limb  68   a ,  70   a  of the clamping element  14   a . The partial regions  30   a ,  32   a  of the clamping head  20   a  in this case are realized, respectively, so as to be integral with one of the limbs  68   a ,  70   a  of the clamping element  14   a . Consequently, the clamping head  20   a  is disposed in a resilient manner on the clamping element  14   a , by means of the limbs  68   a ,  70   a . In addition, the partial regions  30   a ,  32   a  each have a clamping face  72   a ,  74   a , which, when the clamping unit  12   a  is in a clamping mode, for the purpose of chucking the working tool  16   a  in the axial direction  18   a , bear against at least a partial face of the working tool  16   a . The clamping faces  72   a ,  74   a  are provided so that, when in the clamping mode, they apply a clamping force to the working tool  16   a , in the clamping mode, along the axial direction  18   a.    
     Furthermore, the clamping unit  12   a  has a spring element  76   a , which is provided to apply a spring force to the clamping element  14   a , along the axial direction  18   b . The spring element  76   a  in this case is realized as a compression spring  78   a . It is also conceivable, however, for the spring element  76   a  to be constituted by a different spring element, considered appropriate by persons skilled in the art, such as, for example, a tension spring, a disc spring, etc. Further, it is likewise conceivable for the clamping unit  12   a  to have more than one spring element  76   a  for applying a spring force to the clamping element  14   a . The clamping element  14   a , when in a mounted state, extends along the axial direction  18   b , through the compression spring  78   a . The compression spring  78   a  is therefore disposed at least around a partial region of the clamping element  14   a , along the circumferential direction  62   a . The compression spring  78   a , when in a mounted state, is supported, by means of an end  80   a , on a bearing face  82   a  of the clamping element  14   a . The bearing face  82   a  in this case is realized in the form of a circular ring. Further, the compression spring  78   a  is supported, by means of a further end  84   a , on a retaining ring  86   a  disposed on the tool receiver  58   a . The retaining ring  86   a  is provided to bias the compression spring  78   a . The retaining ring  86   a  in this case, when in a mounted state, is disposed in a groove in the hollow shaft  56   a . The further end  84   a  is disposed on a side of the compression spring  78   a  that is opposite a side of the compression spring  78   a  on which the compression spring  78   a  is supported, by means of the end  80   a , on the bearing face  82   a  of the clamping element  14   a . The compression spring  78   a , therefore, as viewed along the axial direction  18   a , is disposed between the bearing face  82   a  of the clamping element  14   a  and the retaining ring  86   a  disposed on the tool receiver  58   a . The retaining ring  86   a  in this case is disposed on a side of the tool receiver  58   a  that faces in axial direction  18   a  away from a mounted working tool  16   a.    
     For the purpose of actuating the clamping element  14   a , the clamping unit  12   a  has an operating unit  88   a  ( FIG. 1 ). The operating unit  88   a  comprises an operating lever  90   a , which is mounted so as to be rotatable about the rotation axis  54   a  of the hollow shaft  56   a . Further, the operating unit  88   a  has a mechanism (not represented in greater detail here), which is provided to convert a rotary motion of the operating lever  90   a  about the rotation axis  54   a  into a translational motion of the clamping element  14   a  along the axial directions  18   a  and  18   b . The mechanism in this case can be constituted by a transmission, a control cam or other mechanisms, already known to persons skilled in the art, for converting a rotary motion into a translational motion. While the portable power tool  38   a  is in operation, the operating unit  88   a , when in the clamping mode, is decoupled from an oscillating motion of the clamping element  14   a , in a manner already known to persons skilled in the art. In the tool changing mode, the operating unit  88   a  is coupled to the clamping element  14   a  and/or to the clamping head  20   a , in a manner already known to persons skilled in the art, in order to release a clamping force. After the clamping force of the clamping element  14   a  and/or of the clamping head  20   a  has been released, the operator can remove the working tool  16   a  from the tool receiver  58   a.    
     The tool clamping device  10   a  additionally has a motion conversion unit  22   a , which is provided to move the clamping head  20   a , in dependence on a motion of the clamping element  14   a  at least substantially along the axial direction  18   b . The clamping head  20   a  in this case is swiveled, by means of the motion conversion unit  22   a , about an axis running perpendicularly in relation to the axial directions  18   a  and  18   b . The clamping head  20   a  in this case is moved at least substantially along a main motion direction, which runs at least substantially perpendicularly in relation to the axial directions  18   a  and  18   b . The motion conversion unit  22   a  is realized as an expansion unit  92   a , which is provided to move the two partial regions  30   a ,  32   a  of the clamping head  20   a , which are movable relative to each other, in opposing directions  34   a ,  36   a  relative to each other, in an operating mode of the clamping unit  12   a . The motion conversion unit  22   a  in this case has a motion conversion element  24   a , which is provided to move the clamping head  20   a  in a direction differing from the axial directions  18   a  and  18   b , for the purpose of achieving an axial overlap of the clamping head  20   a  and the working tool  16   a , when the clamping unit  12   a  is in the clamping mode. The motion conversion element  24   a  is realized as a stud  26   a . It is also conceivable, however, for the motion conversion element  24   a  to be realized as a pin and/or as a slotted pin. Other designs of the motion conversion element  24   a , considered appropriate by persons skilled in the art, are likewise conceivable. 
     For the purpose of mounting the working tool  16   a  on the tool receiver  58   a , the operating lever  90   a , starting from a position in which the operating lever  90   a  bears against the power-tool housing  42   a , is moved by the operator in a direction oriented away from the power-tool housing  42   a  and is therefore rotated about the rotation axis  54   a . As a result, the clamping element  14   a  is moved along the axial direction  18   a , in the direction of the tool receiver  58   a . The clamping unit  12   a  is in the tool changing mode. The operator, while maintaining the turning of the operating lever  90   a  about the rotation axis  54   a , can put the working tool  16   a  on to the tool receiver  58   a . It is also conceivable, however, for the operating unit  88   a  to have a latching device (not represented in greater detail here), which is provided to lock the operating lever  90   a  in a position, such as, for example, in a position of the operating lever  90   a  that corresponds to the tool changing mode. The working tool  16   a  is guided by the operator, with a central insertion opening over the clamping head  20   a , until the working tool  16   a  bears against the tool receiver  58   a  and the latching cams  66   a  of the tool receiver  58   a  are disposed in the driving recesses  60   a  of the working tool  16   a . As a result, when the clamping unit  12   a  is in the clamping mode, the working tool  16   a  is secured against turning along the circumferential direction  62   a . After a force applied by the operator upon the operating lever  90   a  has been removed, the operating lever  90   a  is moved into an initial position, in the direction of the power-tool housing  42   a , as a result of a spring force of the compression spring  78   a , which acts upon the operating lever  90   a  via the mechanism for converting the rotary motion of the operating lever  90   a  into a translational motion of the clamping element  14   a . The clamping unit  12   a  is consequently in the clamping mode. 
     Upon a motion of the clamping element  14   a , along the axial direction  18   b , in a direction oriented away from the tool receiver  58   a , the two partial regions  30   a ,  32   a  of the clamping head  20   a  are moved on to the motion conversion element  24   a , realized as a stud  26   a , of the motion conversion unit  22   a , realized as an expansion unit  92   a . As soon as the partial regions  30   a ,  32   a  come into bearing contact with the stud  26   a  during the motion along the axial direction  18   b , respectively one slide face  94   a ,  96   a  of the partial regions  30   a ,  32   a  slides along an outer face of the stud  26   a . The slide faces  94   a ,  96   a  have the shape of an arc. Further, the slide faces  94   a ,  96   a  are disposed on a side of the partial regions  30   a ,  32   a  that faces toward the compression spring  78   a . As a result of the motion along the axial direction  18   b  and the sliding of the slide faces  94   a ,  96   a  along the outer face of the stud  26   a , the partial regions  30   a ,  32   a  are moved in the two mutually opposing directions  34   a ,  36   a , until the stud  26   a  bears against, respectively, an expansion face  98   a ,  100   a  of the partial regions  30   a ,  32   a  as a result of the motion of the clamping element  14   a  between the partial regions  30   a ,  32   a . The stud  26   a , as viewed along a direction running perpendicularly in relation to the axial directions  18   a  and  18   b , is disposed between the expansion faces  98   a ,  100   a  of the partial regions  30   a ,  32   a , when in the clamping mode. The clamping head  20   a  is thus expanded by means of the motion conversion element  24   a . Following completion of a clamping operation, the clamping faces  72   a ,  74   a  of the partial regions  30   a ,  32   a  bear against partial faces of the working tool  16   a , and apply a clamping force to the working tool  16   a , along the axial direction  18   a , in the direction of the tool receiver  58   a.    
     In the case of a release operation of the clamping unit  12   a , the operator changes the clamping unit  12   a  from the clamping mode to the tool changing mode. In this case, the operating lever  90   a  is moved by the operator out of the initial position, in the direction oriented away from the power tool-housing  42   a , and rotated about the rotation axis  54   a . The clamping element  14   a  in this case is moved along the axial direction  18   a , in the direction of the tool receiver  58   a . As a result of the motion of the clamping element  14   a  along the axial direction  18   a , in the direction of the tool receiver  58   a , the expansion faces  98   a ,  100   a  of the partial regions  30   a ,  32   a  slide on the outer face of the stud  26   a , until the stud  26   a  becomes disengaged from the expansion faces  98   a ,  100   a . The partial regions  30   a ,  32   a  are moved toward each other as a result of the resilient disposition on the clamping element  14   a . For the purpose of assisting the motion of the partial regions  30   a ,  32   a , the motion conversion unit  22   a  has an inclined face  102   a , which is realized so as to correspond, respectively, to an inclined face  104   a ,  106   a  of the partial regions  30   a ,  32   a . As soon as the stud  26   a  has become disengaged from the expansion faces  98   a ,  100   a , the inclined face  102   a  of the motion conversion unit  22   a  and the inclined faces  104   a ,  106   a  of the partial regions  30   a ,  32   a  of the clamping head  20   a  bear against each other. By means of a combined action of the inclined face  102   a  of the motion conversion unit  22   a  and the inclined faces  104   a ,  106   a  of the partial regions  30   a ,  32   a , and as a result of the motion of the clamping element  14   a  along the axial direction  18   a , in the direction of the tool receiver  58   a , the partial regions  30   a ,  32   a  are moved further toward each other. In this case, an axial overlap of the clamping faces  72   a ,  74   a  of the partial regions  30   a ,  32   a  and of the working tool  16   a  is removed. The working tool  16   a  can thus be removed from the tool receiver  58   a.    
       FIGS. 4 to 7  show an alternative exemplary embodiment. Components, features and functions that remain substantially the same are denoted, basically, by the same references. In order to differentiate the exemplary embodiments, the references of the exemplary embodiments have the suffix letters  a  and  b . The description that follows is limited substantially to the differences in relation to the first exemplary embodiment in  FIGS. 1 to 3 , and reference may be made to the description of the first exemplary embodiment in  FIGS. 1 to 3  in respect of components, features and functions that remain the same. 
       FIG. 4  shows a detail view of a tool clamping device  10   b  when a clamping unit  12   b  of the tool clamping device  10   b  is in a tool changing mode. The tool clamping device  10   b  is disposed in a portable power tool (not represented in greater detail here), which has a structure similar to that of the portable power tool  42   a  from  FIG. 1 . The clamping unit  12   b  has a pin-shaped clamping element  14   b  for chucking a working tool  16   b  in an axial direction  18   b , and has a clamping head  20   b  disposed on the clamping element  14   b . Furthermore, the tool clamping device  10   b  has a motion conversion unit  22   b , which is provided to move the clamping head  20   b , in dependence on a motion of the clamping element  14   b  at least substantially along the axial direction  18   b , in at least one direction differing from the axial direction  18   b.    
     The clamping element  14   b  comprises two partial regions  108   b ,  110   b , which are movable relative to each other. The partial regions  108   b ,  110   b  of the clamping element  14   b  are disposed, so as to be swivellable about an axis running perpendicularly in relation to the axial direction  18   b , in a spindle  40   b  of the portable power tool that is realized as a hollow shaft  56   b . In addition, the partial regions  108   b ,  110   b  are mounted so as to be movable in the hollow shaft  56   b , along the axial direction  18   b . The clamping element  14   b  is disposed in a movable manner on a transmission element  112   b  of the clamping unit  12   b . The transmission element  112   b  is provided to transmit a motion of an operating unit (not represented in greater detail here) of the clamping unit  12   b  to the clamping element  14   b . The clamping head  20   b  likewise has two partial regions  30   b ,  32   b  that are movable relative to each other. The partial regions  30   b ,  32   b  of the clamping head  20   b  are realized, respectively, so as to be integral with one of the partial regions  108   b ,  110   b  of the clamping element  14   b . Further, the partial regions  30   b ,  32   b  of the clamping head  20   b  are disposed, respectively, on the respective partial region  108   b ,  110   b  of the clamping element  14   b . In this case, the partial regions  30   b ,  32   b  of the clamping head  20   b  have an eccentricity relative to a longitudinal axis of the respective partial region  108   b ,  110   b  of the clamping element  14   b  that, at least in one operating state, runs at least substantially parallelwise in relation to the axial direction  18   b.    
     Furthermore, the motion conversion unit  22   b  comprises a motion conversion element  24   b , which is provided to move the clamping head  20   b  in at least one direction differing from the axial direction  18   b , for the purpose of achieving an axial overlap of the clamping head  20   b  and the working tool  16   b , at least when the clamping unit  12   b  is in a clamping mode. The motion conversion element  24   b  is realized as a stud  26   b . Further, the motion conversion unit  22   b  comprises at least one cam member  28   b , in which the motion conversion element  24   b  partially engages. The motion conversion unit  22   b  is thus constituted by a cam mechanism. The cam mechanism in this case is realized as an expansion unit  92   b , which is provided to move the two partial regions  30   b ,  32   ab  of the clamping head  20   b , which are movable relative to each other, in opposing directions  34   b ,  36   b  relative to each other, in at least one operating mode of the clamping unit  12   a.    
     The cam member  28   b  is disposed on the clamping element  14   b . The partial regions  108   b ,  110   b  of the clamping element  14   b  each comprise a cam member  28   b  (only one cam member is represented in the figures). The cam members  28   b  are realized as gate-type slots  114   b  (only one slot represented in the figures) in the partial regions  108   b ,  110   b  of the clamping element  14   b . It is also conceivable, however, for the cam members  28   b  to be designed in a different manner, considered appropriate by persons skilled in the art. The slots  114   b  are provided to define a motion of the respective partial region  108   b ,  110   b  in dependence on a motion of the clamping element  14   b  along the axial direction  18   b , by means of a combined action with the motion conversion element  24   b . The motion conversion element  24   b , when in a mounted state, extends along a direction running perpendicularly in relation to the axial direction  18   b , through the slots  114   b  of the partial regions  108   b ,  110   b . The motion conversion element  24   b  is connected to the hollow shaft  56   b  in a fixed manner. 
     When the working tool  16   b  is being mounted, the clamping unit  12   b  is in a tool changing mode. In this case, the partial regions  108   b ,  110   b  of the clamping element  14   b  are swiveled relative to each other, because of the motion conversion unit  22   b . Consequently, longitudinal axes of the partial regions  108   b ,  110   b  are offset at an angle relative to the axial direction  18   b . The partial regions  30   b ,  32   b  of the clamping head  20   b  are disposed concentrically in relation to the axial direction  18   b , owing to the eccentric disposition on the partial regions  108   b ,  110   b  of the clamping element  14   b , in the region of clamping faces  72   b ,  74   b  of the partial regions  30   b ,  32   b  ( FIG. 5 ). An operator can thus attach the working tool  16   b  to a tool receiver  58   b  of the portable power tool. The working tool  16   b  in this case is guided with a central insertion opening over the clamping head  20   b , until the working tool  16   b  bears against the tool receiver  58   b  and protrusions  64   b  of the tool receiver  58   b  are disposed in driving recesses  60   b  of the working tool  16   b.    
       FIG. 6  shows the clamping unit  12   b  in a clamping mode. As the clamping unit  12   b  is being changed from the tool changing mode to the clamping mode, the partial regions  108   b ,  110   b  of the clamping element  14   b  are swiveled relative to each other during a motion of the clamping element  14   b  along the axial direction  18   b , as a result of a combined action of the motion conversion element  24   b  and the cam members  28   b . Upon a motion of the clamping element  14   b  in a direction oriented away from the tool receiver  58   b , the partial regions  108   b ,  110   b  are swiveled toward each other, because of a geometry of the cam members  28   b . In the clamping mode, the longitudinal axes of the partial regions  108   b ,  110   b  are aligned parallelwise in relation to the axial direction  18   b . Consequently, the partial regions  108   b ,  110   b  overlap at least substantially completely along a direction running perpendicularly in relation to the axial direction  18   b . In this case, the outer edges of the partial regions  108   b ,  110   b  are each in flush alignment with each other along the direction running perpendicularly in relation to the axial direction  18   b.    
     Upon a swivel motion of the partial regions  108   b ,  110   b  of the clamping element  14   b , the partial regions  30   b ,  32   b  of the clamping head  20   b  are moved relative to each other in opposing directions  34   b ,  36   b . The partial regions  30   b ,  32   b  of the clamping head  20   b  are moved substantially along a main motion component, which is aligned perpendicularly in relation to the axial direction  18   b . As a result of the motion of the partial regions  30   b ,  32   b  of the clamping head  20   b , the clamping faces  72   b ,  74   b  of the partial regions  30   b ,  32   b  are placed against the working tool  16   b . Consequently, in the clamping mode, a clamping force is transmitted, along the axial direction  18   b , to the working tool  16   b . The partial regions  30   b ,  32   b  of the clamping head  20   b  are disposed with an offset relative to each other, owing to the eccentric disposition on the partial regions  108   b ,  110   b  in the clamping mode ( FIG. 7 ).