Abstract:
A tool clamping device, in particular an oscillating tool clamping device, includes a clamping unit that has at least one clamping element configured to securely clamp a working tool in an axial direction and at least one clamping head arranged on the clamping element and configured to clamp the working tool at a free end of the clamping unit. The clamping unit further includes a guiding unit configured to guide at least one movement of the working tool along at least one direction of movement that deviates significantly from the axial direction in at least one operating state.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2012/051725, filed on Feb. 2, 2012, which claims the benefit of priority to Serial No. DE 10 2011 005 821.4, filed on Mar. 18, 2011 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     There are already known tool clamping devices that comprise a clamping unit. The clamping unit in this case has a clamping element for securely clamping a working tool in an axial direction, and has a clamping head, which is disposed on the clamping element and which is provided for clamping the working tool at a free end of the clamping unit. 
     SUMMARY 
     The disclosure is based on a tool clamping device, in particular an oscillating-tool clamping device, comprising a clamping unit that has at least one clamping element for securely clamping a working tool in an axial direction, and has at least one clamping head, which is disposed on the clamping element and which is provided for clamping the working tool at a free end of the clamping unit. 
     It is proposed that the clamping unit have a guide unit, which is provided for guiding at least one movement of the working tool along at least one movement direction that differs substantially from the axial direction, in at least one operating state. 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 form-fit and/or by means of a force-fit. In particular, the clamping unit has an operating unit. The term “operating unit” is intended here to define, in particular, a unit having at least one operating element that can be actuated directly by an operator, and which is provided to influence and/or alter a process and/or a state of a unit coupled to the operating element, through an actuation and/or through an input of parameters. A “working tool” is to be understood to mean, in particular, a blade-type tool that is provided, in particular, for performing material-removing work, preferably sawing, on a workpiece. The term “axial direction” is intended here to define, in particular, a direction that runs preferably at least substantially parallelwise in relation to a pivot axis and/or rotation axis of a drive shaft of a portable power tool, which drive shaft is provided to drive the working tool. “Substantially parallelwise” is intended 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 element” is to be understood to mean, in particular, an element provided to transmit a clamping force, which is preferably generated by a spring unit. Preferably, the clamping element is at least partially disposed in a hollow shaft and mounted, in particular, on bearing means that are disposed on the hollow shaft. A “clamping head” is to be understood here to mean, in particular, a component having at least one clamping surface that, for the purpose of securely clamping the working tool in the axial direction, bears at least against a partial surface of the working tool, and that applies a clamping force to the working tool along the axial direction and presses the working tool, in particular, against a tool receiver. A “tool receiver” is to be understood to mean, in particular, a component provided to receive a working tool in a receiving region, and to effect a form-fitting and/or force-fitting connection with the working tool in the circumferential direction. In particular, the tool receiver is connected to the drive shaft in a form-fitting and/or materially bonded manner. A “receiving region” is to be understood to mean, in particular, a near region of the tool receiver that is completely filled by a working tool securely clamped in the clamping unit. A “free end” of the clamping unit is to be understood to mean, in particular, a region of the clamping unit that is freely accessible by an operator, such that, preferably, it is possible to dispense with use of a tool and, in particular, to dispense with removal of housing parts. A “guide unit” is to be understood to mean, in particular, a unit provided to constrain a mounting movement that differs from a purely axial mounting movement, a movement about and/or along the axial direction, and which is distinguished, in particular, from a guide unit that allows a non-mounted working tool, through a single translational movement, to move into the receiving region of the tool receiver in a movement direction that is at least substantially parallel to the axial direction. Furthermore, the guide unit, in particular following an adjustment of an element of the guide unit, can have sufficient clearance to enable the working tool to tilt by an angle of up to 50° in respect of a plane whose normal vector is oriented at least substantially parallelwise in relation to the axial direction. A “substantial difference” of a movement direction from the axial direction is to be understood to mean, in particular, that the movement direction and the axial direction enclose an angle that is greater than 30°, advantageously greater than 60°, and preferably greater than 85°. The design of the tool clamping device according to the disclosure advantageously enables the working tool to be securely clamped and/or released without the use of tools. 
     Advantageously, the clamping head is 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. It is also conceivable, however, for the clamping head to be connected to the clamping element by means of a form-fitting and/or force-fitting connection, in particular in a rotationally fixed manner. The fact that the clamping head is designed so as to be integral with the clamping element makes it possible, advantageously, to realize savings in assembly work and costs. 
     In a further design of the disclosure, it is proposed that the guide unit have a receiving region that, as viewed in a clamping direction, is disposed at least partially behind the clamping head of the clamping element. A “clamping direction” is to be understood to mean, in particular, a direction in which the clamping head, when in an operating state with a securely clamped working tool, exerts a force upon the working tool. Advantageously, an axial overlap with a clamping surface of the clamping head can be achieved through the movement of the working tool. 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, wherein, in particular, a straight line along the axial direction intersects the two components. Preferably, the clamping surface of the clamping head overlaps at least a partial region of the working tool along the axial direction, at least in one operating state, in which the working tool is securely clamped on a tool receiver by means of the clamping head. In particular, an axial overlap is maintained in the case of a change of position, preferably one resulting from a rotation about an axis of a shaft of the working tool. In particular, it is possible for the working tool to be securely clamped and/or released without the use of tools. 
     It is additionally proposed that the clamping head be disposed eccentrically in relation to a longitudinal axis of the clamping element. In the case of the clamping head being integral with the clamping element, a clamping head is to be understood to mean, in particular, a smallest part of the clamping element that is delimited by a plane whose normal vector is disposed substantially parallelwise in relation to the axial direction, which plane, as viewed from the free end, is located behind the clamping surface, and includes at least the clamping surface. That an element is disposed “eccentrically” in relation to an axis is to be understood to mean, in particular, that a centroid, preferably a geometric centroid, of the element is at a greater distance from the axis than at least 3%, advantageously at least 8%, and preferably at least 20% of a maximum extent of the element. A “longitudinal axis” of the clamping element is to be understood to mean, in particular, an axis of the clamping element that is substantially parallel to the axial direction when the clamping element is in a mounted state. In particular, an axial overlap of the clamping head with the working tool can be achieved in a simple manner. 
     It is furthermore proposed that the clamping head have a chamfer, at least on a side that faces away from a clamping surface. In particular, a smallest extent of the chamfer is greater than 1 mm, and advantageously greater than 2 mm. Advantageously, the chamfer has an angle in relation to the longitudinal axis of the clamping element that deviates by less than 40°, in particular less than 20°, and preferably less than 5° from an angle of 45°. In particular, ease of mounting can be achieved. 
     Preferably, the clamping head has at least one clamping surface that is disposed asymmetrically, preferably eccentrically, in respect of a longitudinal axis of the clamping element. In particular, an axial overlap of the clamping head with the working tool can be achieved in a simple manner. 
     In a further design, it is proposed that the clamping unit have a clamping distance of between 1.5 mm and 3 mm in length. In particular, the clamping head is moved by the clamping distance during a complete operation of mounting and clamping the working tool. 
     The disclosure is additionally based on a portable power tool, in particular a hand-held power tool having a spindle that can be driven in an oscillatory manner, having a tool clamping device according to the disclosure. A “portable power tool” is to be understood here to mean, in particular, a power tool, in particular a hand-held power tool, that can be transported by an operator without the use of 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, a high degree of operating comfort can be achieved for an operator of the hand-held power tool. 
     The tool clamping device according to the disclosure in this case is not intended to be limited to the application and embodiment described above. In particular, the tool clamping device according to the disclosure, for the purpose of implementing a functioning mode described herein, can have a number of individual elements, components and units that differs from a number stated herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages are given by the following description of the drawings. The drawings show an exemplary embodiment of the disclosure. The drawings, 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 drawings: 
         FIG. 1  shows a system according to the disclosure, comprising a power tool that has a tool clamping device according to the disclosure and a mounted working tool, in a schematic representation, 
         FIG. 2  shows a view of the clamping unit in the clamping direction, 
         FIG. 3  shows a detail portion of a section along the rotation axis of the hollow shaft, with a mounted and securely clamped working tool, in a schematic representation, 
         FIG. 4  shows a further detail portion of the tool clamping device according to the disclosure, with a released working tool, and 
         FIG. 5  shows a further detail portion of the tool clamping device according to the disclosure, in a schematic representation. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a system consisting of an electrically operated portable power tool  38 , and of a working tool  16 , which is realized as a saw blade. The power tool has tool clamping device  10 , realized as an oscillating-tool clamping device, which is provided for securely clamping the working tool  16  in the power tool  38 . The portable power tool  38  comprises a power-tool housing  42 , which encloses an electric-motor unit  44 , a transmission unit  46  and an output unit  48  of the portable power tool  38 . The power-tool housing  42  in this case comprises two housing half-shells  50 ,  52 , which are detachably connected to each other along a plane running through an axial direction  18 . It is also conceivable, however, for the power-tool housing  42  to have two or more pot-shaped housing parts that can be detachably connected to each other. The axial direction  18  runs along and/or parallelwise in relation to a rotation axis  54  of a hollow shaft  56 , realized as a spindle  40 , of the output unit  48  ( FIG. 3 ). The hollow shaft  56  is provided, when in a mounted state, to drive a working tool  16  in an oscillating manner. An oscillating drive of the working tool  16  in this case is effected in a manner already known to persons skilled in the art, such as, for example, by means of a journal (not represented in greater detail here) of the transmission unit  46 , which journal is disposed eccentrically on a drive shaft of the electric-motor unit  44  and, by means of a rocker arm and rocker sleeve (not represented in greater detail here) of the transmission unit  46 , drives the hollow shaft  56  when the portable power tool  38  is in operation. The hollow shaft  56 , realized as a spindle  40 , can thus be driven in an oscillating manner. The working tool  16  can be fastened to a tool receiver  58  of the output unit  48  for the purpose of performing material-removing work on workpieces. The tool receiver  58  is integral with the hollow shaft  56 . A pivoting motion of the hollow shaft can be transmitted to the tool receiver  58 . The tool receiver  58  has twelve latching cams  66 , which are distributed uniformly along a circle and which are provided to be connected in a form-fitting manner to twelve driving recesses  60  realized on the working tool  16  ( FIG. 2 ). 
     The tool clamping device comprises a clamping unit  12 . The clamping unit has a clamping element  14  for securely clamping a working tool  16  in an axial direction  18 , and has a clamping head  20 , which is disposed on the clamping element  14  and which is provided for clamping the working tool  16  at a free end  30  of the clamping unit  12 . The clamping element  14  is partially disposed in the hollow shaft  56 . The clamping element  14  is mounted in a bearing element  24  of the hollow shaft  56 . The clamping unit  12  additionally has a guide unit  22 , which is provided, when in an operating state that differs from an operating state with a securely clamped working tool  16 , to guide a movement of the working tool  16  along a movement direction  34  that differs substantially from the axial direction  18 . The guide unit  22  is constituted by the clamping element  14 , the clamping head  20  disposed on the clamping element  14 , and the tool receiver  58 . 
     The clamping head  20  is integral with the clamping element  14 . The guide unit  22  has a receiving region  59 , which, as viewed in a clamping direction  36 , is disposed at least partially behind the clamping head  20  of the clamping element  14 . The clamping head  20  is disposed eccentrically in relation to a longitudinal axis  28  of the clamping element  14 . The clamping head has a clamping surface  72  that is disposed asymmetrically in respect of the longitudinal axis  28  of the clamping element  14 . The clamping head  20  has a chamfer  26  on a side that faces away from the clamping surface  72 . The clamping unit  12  has a clamping distance  32  of 2 mm in length. 
       FIG. 2  shows the power-tool clamping device  10  in a view in the clamping direction  32 . The working tool  16  is connected to the tool receiver  58  in the circumferential direction  62  by means of the latching cams  66  and the driving recesses  60 . A clamping head  20  disposed on the clamping element  14 , eccentrically in relation to the longitudinal axis  28  of the clamping element  14 , has a clamping surface  72 . The clamping surface  72  is disposed eccentrically in respect of the longitudinal axis  28  of the clamping element  12 . The clamping head  20  has a chamfer  26 , which facilitates placement of the working tool  16 , which has a placement hole  64 . The chamfer  26  has an angle of inclination of 45° relative to the longitudinal axis  28  of the clamping element  14 , and a width of 2 mm. The placement hole  64  is disposed centrally between the driving recesses  60  of the working tool  16 . Also conceivable, however, is a design in which the clamping head  20  is disposed on the longitudinal axis  28  of the clamping element  14  and is mushroom-shaped, and a working tool  16  has a placement hole  64  disposed eccentrically in relation to a central point between the driving recesses  60 . 
       FIG. 3  shows a schematic detail portion of the output unit  48  and of the tool clamping device  10  when in an operating state, with a securely clamped working tool  16 . The clamping unit  12  has a spring unit  76 . By means of a biased spiral compression spring  78 , the spring unit  76  generates a clamping force that is transmitted to the clamping head  20  via the clamping element  14 . By means of this clamping force, the clamping head  20  presses the working tool  16 , in the clamping direction  36 , against the tool receiver  58 . 
     The working tool  16  is disposed in a receiving region  59 . The latching cams  66  of the tool receiver  58  engage in the driving recesses  60  of the working tool  16 . The receiving region  59  is disposed partially behind the clamping head  20 , as viewed in the clamping direction  36 . A clamping surface  72  of the clamping head  20  is disposed on the back side of the clamping head  20 , as viewed in the clamping direction  36 . In an alternative design, the clamping force is generated by means of a screw thread, through tightening of a nut and/or a screw. Additionally conceivable are designs in which disk springs are used instead of the spiral compression spring  78 . 
     To enable the clamping element  14  to be actuated without the use of tools, the clamping unit  12  has an operating unit  88  ( FIG. 1 ). The operating unit  88  comprises an operating lever  90 , which is mounted so as to be rotatable about the rotation axis  54  of the hollow shaft  56 . The operating unit  88  additionally has a mechanism (not represented in greater detail here) provided to convert a rotary motion of the operating lever  90  about the rotation axis  54  into a translational movement of the clamping element  14  along the axial direction  18 . The mechanism in this case can be constituted by a transmission, a control curve or other mechanisms, already known to persons skilled in the art, for converting a rotary motion into a translational movement. In an operating state, with a securely clamped working tool, the operating unit  88  is decoupled from an oscillating motion of the clamping element  14  during operation of the portable power tool  38 , in a manner already known to persons skilled in the art. In an operating state that differs from an operating state with a securely clamped working tool, the operating unit  88  is coupled to the clamping element  14  and/or to the clamping head  20 , in a manner already known to persons skilled in the art, for the purpose of releasing a clamping force. 
       FIG. 4  shows the portion according to  FIG. 3  in an operating state that differs from a state with a securely clamped working tool  16 . In order to achieve this operating state, the operating lever  90  has been actuated. The clamping element  14  has been displaced by the operating unit  88 , contrary to the clamping direction  36 , by a clamping distance  32 . The length of the clamping distance  32  is 2 mm. 
     In  FIG. 5 , the working tool  16  has been released from the receiving region. The clamping head  20  of the clamping element  14  and the tool receiver  58  constitute a guide unit  22 , which guides a movement of the working tool  16  in the movement direction  34 . The movement direction  34  is substantially perpendicular to the rotation axis  54  of the hollow shaft  56 , and consequently to the axial direction  18 . Following movement of the working tool  16  along the movement direction  34  by a distance of 3 mm, the working tool  16  is in a position in which the placement hole  64  can be guided over the clamping head  20  in the axial direction, and the working tool  16  can thus be released from the portable power tool  38 . Both the clamping element  14  and the clamping head  20  remain connected to the tool clamping device  10  during demounting or mounting of the working tool  16 . In the case of mounting of the working tool  16 , placement of the placement hole  64  over the clamping head  20  is assisted by the chamfer  26 . The entire operation of mounting or demounting the working tool  16  is performed without the use of tools.