Abstract:
A hand power tool has a disk-shaped tool, and a clamping device for clamping the tool, the clamping device including at least one flange and a clamping unit for clamping the tool to the at least one flange and passing through the tool, the clamping unit and the at least one flange being configured on a key-end-keyhole principle, so that after passing axially through one another and subsequently being rotated counter to one another, the clamping unit and the at least one flange axially fix one another at least in one axial direction.

Description:
CROSS-REFERENCE 
   The invention described and claimed hereinbelow is also described in PCT/EP 2004/052759, filed on Nov. 2, 2004 and DE 103 61 810.4, filed on Dec. 30, 2003. This German Patent Application, whose subject matter is incorporated here by reference, provides the basis foe a claim of priority of invention under 35 U.S.C. 119 (a)–(d). 
   BACKGROUND OF THE INVENTION  
   The present invention is related to a hand power tool. 
   From European Patent Disclosure EP 152 564, a hand power tool is known whose disklike tool can be detachably secured to a work spindle for rotational slaving by means of flanges that can be locked in screwable or bayonetlike fashion. 
   This hand power tool has a fast-action clamping means, with a tension spindle which passes through the work spindle and pulls the outer of the flanges against the disklike tool. The clamping stroke of the tension spindle must be adapted to disklike tools of different thickness, so that an adequate clamping force for fixation of a given tool can be achieved. 
   Adapting the clamping stroke is complicated and time-consuming. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a hand power tool with a clamping device, which eliminates the disadvantages of the prior art. 
   Because one flange defines different clamping planes, the clamping means to fit the commercially available disklike tools of different thickness can always be associated with them without calibration effort. This assures that both tools with a maximum thickness and those with a minimum thickness can always be clamped with an adequate clamping force to the hand power tool. 
   Because the clamping means has three clamping tabs, which are braced against a corresponding support edge of the one flange, relatively high clamping forces can be transmitted. 
   Because the flange forms two support edges, each in a different plane, on its front side and its back side, a total of four support planes are available with the flange, and with these planes all the commercially available disklike tools can be clamped. 

   
     DRAWINGS 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims, the invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
       FIG. 1 , a longitudinal section through the hand power tool; 
       FIG. 2 , a top view on the front side of the clamping flange; 
       FIG. 3 , a first longitudinal section through the clamping flange in a first clamping position; 
       FIG. 4 , a second longitudinal section through the clamping flange in a second clamping position; 
       FIG. 5 , a third longitudinal section through the clamping flange in a third clamping position; 
       FIG. 6 , a fourth longitudinal section through the clamping flange in a fourth clamping position; 
       FIG. 7 , a detail of a tension spindle; 
       FIG. 8 , a detail of the clamping means; 
       FIG. 9 , a cross section of the clamping means with the clamping flange; 
       FIG. 10 , the cross section of the clamping means as a detail; 
       FIG. 11 , a top view on the back side of the clamping flange. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a hand power tool  10 , designed as a right-angle grinder, in longitudinal section. The hand power tool  10  comprises an elongated motor housing  12 , to which a gearbox  14  bent downward at an angle is flanged. The motor housing  12  supports a motor  16 , whose motor shaft  18  protrudes into the gearbox  14 . The end of the motor shaft  18  supports a motor pinion  22 , designed as a conical gear wheel. The motor pinion  22 , together with a ring gear  24 , forms an angular gear  20 . In a manner fixed against relative rotation, the ring gear  24  embraces a power takeoff shaft  26 , which in turn, on its end, carries a disklike tool in the form of a grinding wheel  27  in a manner fixed against relative rotation. The grinding wheel  27  is guided by a central recess, not identified by reference numeral, over the free end of the power takeoff shaft  26  and secured replaceably to it in clampable fashion. It is braced in centered fashion on the machine on the centering collar  31  of a support flange, which is seated, in a manner fixed against relative rotation and axially secured, to a stepped collar  28  of the power takeoff shaft  26 . 
   From the side facing away from the machine, or from outside, a clamping flange  32  is braced on the grinding wheel  27 . With its front side  570 , the clamping flange—half of it is shown—is oriented outward on the left in the viewing direction, and with its back side  590 , it is oriented toward the grinding wheel  27 . In this position, the clamping flange  32  is intended for receiving grinding wheels  27  of great thickness, of about 5 mm, and aids the clamping system in achieving optimal clamping force exerted by the clamping springs  40 , installed in the upper region of the gearbox  14  and designed as cup springs. 
   On the right in the viewing direction, the clamping flange  32 , only half of which is also shown, is oriented with its back side  590  outward and with its front side  570  toward the grinding wheel  27 . In this position, the clamping flange  32  is intended to receive grinding wheels  27  of minimal thickness, of approximately 0.8 mm, and also helps the clamping system attain an optimal clamping force, which is exerted by the clamping springs  40 , installed in the upper region of the gearbox  14  and designed as a cup spring assembly—axially secured via a snap ring  42 —in the region of the upper end  38  of the tension spindle. 
   The clamping shaft  35  of a mushroom-shaped clamping head  36 , which belongs to the tension spindle  34 , reaches through the clamping flange  32  through its center hole  54  and is braced on the outside, with a flat clamping face  37 , on the clamping edge  56  of the clamping flange  32 . The clamping head  36  and the center hole  54  have a star-shaped embodiment corresponding to one another, on the order of a key-and-keyhole or bayonet mount system, in which after being inserted through and then rotated, axial bracing of the parts against one another with engagement from behind is accomplished, as will be described in further detail hereinafter. 
   On the outermost, upper end  38  of the tension spindle, a roller bearing support ball  39  is located as wear protection, and on it, a clamping lever  44  is braced with its eccentric region  46 , when this lever is pivoted about its pivot axis  48  for releasing the grinding wheel  27  and in the process presses the tension spindle  34  downward. If, in the release position, the clamping head  36  is axially released from the clamping flange  32 , then this flange can be rotated such that its star-shaped recesses  68  on the edge of the center hole  54  coincide with the star-shaped radial clamping tabs  66  ( FIG. 8 ) of clamping head  36 , and thereupon the clamping flange  32  and then also the grinding wheel  27  can be removed axially from the right-angle grinder  10 . 
   The work shaft  26 , embodied as a hollow shaft, is penetrated centrally by the tension spindle  34  and is supported rotatably in a respective upper and lower spindle bearing  50 ,  52 . 
   The clamping flange  32 , shown from its front side  570  in  FIG. 2 , allows the circular center hole  54  to be seen, which is pierced radially outward by three star-shaped recesses  68  going beyond it. The clamping edge  56  can also be seen, which extends annularly—having the differential diameter of the recesses  68  and the center hole  54 . 
   The clamping edge  56  of the clamping flange  32  is interrupted at regular intervals by three recesses  68  and forms three support tabs  55 , which have two first steplike clamping planes  57 ,  58  on the front side  570  and two further steplike clamping planes  59 ,  60  on the back side  590 , on which planes the three clamping tabs  66  of the clamping head  36  can be braced by their flat clamping face  37 , after appropriate rotation of the clamping flange  32  relative to the clamping head  36 . As a result, the clamping flange has four different clamping planes, with which all the commercially available grinding wheels can be securely clamped with little effort to the right-angle grinder  10 . 
   On its front side  570 , the clamping flange  32  has an encompassing, narrow marking groove  33   a , and on its back side  590  ( FIG. 11 ), it has an encompassing wide marking groove  33   b ; with these grooves, the front and back sides  570 ,  590  can easily be told apart. 
     FIGS. 3 ,  4 ,  5  and  6  show a detail of the lower region of the power takeoff shaft  26  with the support flange  30 , the clamping flange  32 , and the clamping head  36 ; in  FIG. 3 , the clamping flange  32  is braced with its front side  570 , that is, its first support face  62 , on a minimally thin grinding wheel  27  and securely fastens this grinding wheel. In the process, the clamping head  36 , with its clamping face  37 , is braced against the axially farthest outwardly positioned clamping plane  57 , so that the optimal clamping force between the support and clamping flanges  30 ,  32  exists in a gap width range of approximately 0.7 to 1.7 mm. 
   In  FIG. 4 , unlike  FIG. 3 , the clamping head  35  is braced against the axially inner clamping plane  58 , so that the optimal clamping force between the support and clamping flanges  30 ,  32  exists at a gap width of approximately 1.7 to 2.8 mm. 
   In  FIG. 5 , unlike  FIGS. 3 and 4 , the clamping flange  32  is braced by its back side  590 , that is, its second support face  64 , on a grinding wheel  27  that is not so thin and securely clamps it. The clamping head  36  is braced against the axially outer clamping plane  59 , so that the optimal clamping force between the support and clamping flanges  30 ,  32  exists at a gap width of approximately 2.9 to 4 mm. 
   In  FIG. 6 , as in  FIG. 5 , the clamping flange  32  is braced by its back side  590 , that is, its second support face  64 , on a thicker grinding wheel  27  and securely clamps it. The clamping head  36  is braced against the axially inner clamping plane  60 , so that the optimal clamping force between the support and clamping flanges  30 ,  32  exists at a gap width of approximately 4 to 5.1 mm. 
     FIG. 7  shows the tension spindle  34  as a detail; the clamping shaft  35 , clamping head  36 , clamping face  37 , and the radial clamping tabs  66 , which are located inside a common mushroom-shaped contour, are especially clearly visible. 
     FIG. 8  shows the face end of the tension spindle  34 , clearly showing its cylindrical shape and the radial clamping tabs  66 —corresponding to the radial recesses  68  of the clamping flange  32 , or its center hole  54 . 
     FIG. 9  shows a cross section of the clamping flange  32  with the clamping flange  32  which is shown in the preceding figures and explained there, with the tension spindle  34  engaging through the center hole  54  and the clamping head  36  with the clamping shaft sitting axially on the upper clamping plane  58 . or in other words axially spaced form the lower clamping plane, as a unit already shown in  FIG. 3 . It can be seen that the clamping flange  32  on a front side  570  has a circumferential small marking groove  33   a  and on its rear side  590  has a circumferential wide marking groove  33   b , by means of which front and rear sides  570 ,  590 , or their first and second supporting faces  62 ,  64  are easily distinguishable from one another. 
     FIG. 10  shows a cross-section of the clamping flange  32  as a unit which is shown in preceding figures, wherein—as shown in  FIG. 9 , in its front side  570  the circumferential, small marking groove  33   a  and on its rear side  590  the circumferential wide marking groove  33   b  and the center hole  54  can be seen. Moreover, the support faces  62 ,  64  as well as the stepped clamping faces  57 ,  58 ,  59  and  60  formed on three symmetrical support tabs  55  are clearly shown. 
     FIG. 11  shows a plan view of the rear side  590  or the second support face  64  of the clamping flange  32  which is shown in the preceding figures and explained there, and the design of the three clamping tabs  55  with the stepped clamping faces  57 ,  58 ,  59  and  60 .