Abstract:
The invention relates to a hand-held power tool having a bearing race inserted into a bearing socket. The bearing socket and the bearing race have recessed ring sectors positioned relative to one another in an overlapping manner. The ring sector of the bearing race is configured by breaking out a circumferential section of the bearing race, which is defined by predetermined breaking points.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP2008/063024 filed on Sep. 29, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a hand-held power tool as well as an assembly process for it. 
     2. Description of the Prior Art 
     Hand-held power tools of the type mentioned above, with an output element that is guided in a bearing race, which is situated in an annular, encompassing bearing socket, are known from practical experience. The part of the bearing socket surrounding the bearing race is constituted by the free end of a neck of an intermediate flange through which the output element extends. A radial access to the output element, whether for drive purposes and/or in connection with the assembly process, is only possible outside the region of the bearing socket due to the closed embodiment of the bearing race and bearing socket. This has a negative impact on assembly options and on the possibilities for access to the output element on the drive side and requires a corresponding overall length for the intermediate flange in the positioning of the drive access in the region of the intermediate flange. 
     The as yet unpublished German patent application DE 10 2007 014 758 has already proposed having the bearing socket and bearing race for an output element in a hand-held power tool be embodied in the form of an open ring when cut-out ring segments are situated congruent to each other. 
     OBJECT AND SUMMARY OF THE INVENTION 
     Based on a hand-held power tool of the type mentioned at the beginning, the object of the invention is to expand the possibilities for accessing the output element without thereby complicating the installation of the bearing race in the bearing socket and/or negatively impacting the guidance quality of the bearing race for the output element. 
     In the hand-held power tool according to the invention, the bearing socket and the bearing race are embodied in the form of an open ring, with cut-out ring sectors that are situated congruent to each other and the cut-out ring sector of the bearing race is embodied so that a circumference segment—which is delimited by detachment points, in particular desired fracture points—is detached, in particular broken out. 
     This embodiment of the bearing race makes it possible not only to manufacture it as a closed bearing race, but also to insert it in a precisely fitting way into the surrounding circular or oval annular bearing socket so that regardless of manufacture-dictated and/or material-dictated inherent stresses, the bearing race is in its desired shape for the insertion into the bearing socket and due to the support of the bearing socket, maintains the manufactured shape that is designed for being supported in a dimensionally stable fashion in the bearing socket even when the open ring form is produced by removing, in particular breaking out, the circumference section delimited by detachment points, in particular desired fracture points. 
     As a result, the same installation prerequisites exist as for a closed bearing race and, in accordance with matching dimensional ratios, the bearing race can be inserted without hindrance into the bearing socket in accordance with the respective fit conditions present. Any material-dictated and/or manufacture-dictated inherent stresses in the bearing race that could result in deviations from the predetermined desired shape in the case of the open ring form thus continue to have no effect on the installation and lastly, have no negative effect on the guidance quality of the bearing race for the output element even after the breaking-out of the circumference section delimited by the desired fracture points, since for the bearing race that is now open, the bearing socket constitutes a dimensionally stable support that is also sufficient for the optional form-locked anchoring of the bearing race in the bearing socket. For such an anchoring, in particular a rotationally-fixed mounting, of the bearing race, it is also optionally possible for grooves to be additionally provided, preferably on the end surface, which cooperate with corresponding counterpart elements provided in the bearing socket to assure the required fixing and possibly also axial positioning of the bearing race. 
     The assembly method according to the invention is particularly suitable for bearing races that are preferably embodied in the form of slide bearing races composed of brittle materials, primarily brittle-fracturing materials. These materials particularly include sintered materials or other materials prone to brittle fracturing in which inherent stresses also arise during manufacture, which can result in deviations from the desired shape when the bearing race is in the broken-open state. 
     Furthermore, the invention also relates to a bearing race as such that has a ring section—which is delimited by detachment points, in particular desired fracture points, and is to be detached, in particular broken out—that can in particular be used in hand-held power tools of the above-mentioned type as well as in connection with an above-mentioned assembly method and which, despite its provided use as an open bearing race, is to be produced in a closed form and thus can also be composed of materials in which, as in sintered materials, inherent stresses can arise during their manufacture and could result in deformations in the discontinuous, i.e. open, bearing race. 
     In the scope of the invention, the desired fracture points can be embodied in the form of notches provided in the inner and/or outer circumference of the bearing race, possibly notches that are situated congruent to each other, so that only comparatively thin bridge pieces remain. 
     In connection with notches provided on one side, in particular on the inside, it can be useful to provide a thickened region on the outer circumference of the bearing race in the region coinciding with each notch in order, during the manufacture, to achieve a continuous, essentially uniform material cross section regardless of the presence of the notch. The thickened region can be easily removed after the manufacture, for example after the pressing procedure when using sintered materials, by means of grinding, stripping, or similar machining procedures. 
     With regard to the rotary securing of the bearing race, it can be useful to also provide it with notches in the end surface, which are associated with corresponding counterpart elements on the respective bearing socket. 
     Other advantages and suitable embodiments can be inferred from the description of the figures, and from the drawings. 
    
    
     
       BREIF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention are described in further detail in the ensuing description in conjunction with the drawings, in which: 
         FIG. 1  is a simplified depiction of a rotary hammer as an example of a hand-held power tool embodied according to the invention, 
         FIG. 2  is a perspective depiction of an intermediate flange of the rotary hammer, which, terminating its end oriented toward the tool, has a bearing with a bearing socket for a bearing race, which guides the output element to be connected to the tool, 
         FIGS. 3 and 4  show the bearing race in a perspective view and a view from the end surface, 
         FIG. 5  is an enlarged depiction of the detail V from  FIG. 4 , 
         FIG. 6  is an enlarged partial top view of a bearing race in which a region of the bearing race that is notched on the inside is thickened on the outside, and 
         FIG. 7  is another perspective depiction of a bearing race. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The hand-held power tool is schematically depicted in  FIG. 1  in the form of a rotary hammer  1 , which at its working end  3  remote from the handle  2  has a tool holder associated with an output element  4 . The output element  4  is embodied in the form of a hammer tube  5 , which, to the rear of the tool holder, accommodates a hammer piston  6  that is driven in an oscillating fashion, in particular oscillating in a reciprocating fashion, and is supported at its end remote from the tool holder by means of a bearing position  7  on the neck  8  of an intermediate flange  9 . The intermediate flange  9  has a base plate  10  that is connected to the output side end plate  11  of the electric motor  12  provided as the drive unit, whose output shaft  13  drives an intermediate shaft  14 . By means of a wobble bearing  15 , the intermediate shaft  14  drives a wobble pin  16  that reaches through the neck  8  of the intermediate flange  9  to engage the hammer piston  6 . In accordance with the wobbling motion, i.e. the reciprocating pivoting motion of the wobble pin  16 , the annular neck  8  through which the wobble pin  16  reaches, according to  FIG. 2 , has a cut-out extending for at least a significant portion of its length and across a ring sector  17 ; this cut-out also extends across the region of the bearing position  7 , which is provided at the end of the neck  8  opposite from the base plate  10  of the intermediate flange  9 . This bearing position  7  is constituted by a bearing socket  18  that is offset toward the outside in stepped fashion, into which a bearing race  19  is inserted; in the depiction according to  FIG. 2 , the cut-out ring sector  17  is depicted as extending continuously and for essentially the same span across the neck  8  and the bearing position  7 . 
     With regard to the intermediate flange  9 , the cut-out of the circumference section corresponding to the ring sector  17  can be embodied in the usual way during manufacture, for example by means of the die-casting method. However, it is also possible for a circumference section—which corresponds to the ring sector  17  to be cut out—to be removed, in particular machined out or broken out, from the neck  8  of the intermediate flange  9 , which is initially closed. 
     The bearing race  19  is inserted axially into the bearing socket  18  that is opened by means of the cut-out ring sector  17 , in fact in the form of a closed bearing race whose circumference section  22  situated congruent to the cut-out circumference section of the bearing socket  18  is delimited by detachment points, in particular desired fracture points  20 , as shown in a closed bearing race in  FIGS. 3 through 7 . In the depiction according to  FIG. 3 , the ring sector  17  of the bearing race  19  to be cut out is comprised of a circumference section  22  that is delimited by wedge-shaped notches  21  and is to be broken out. 
     The bearing race  19 , which like the bearing socket can have a circular or oval shape, is first inserted into the bearing socket  18  in the form of a closed ring and with the circumference section  22  to be broken out positioned congruent to the cut-out ring sector  17  of the bearing race  19 , preferably in a precisely fitting way, so that a dimensionally stable support for the bearing race  19  is provided, which is only missing in the region of the ring sector  17  to be cut out, and the circumference section  22  of the bearing race  19  can be broken out along the desired fracture points  20  and detached from the ring piece without impairing the dimensional stability of the bearing race  19 . 
       FIGS. 3 through 5  show the embodiment of the desired fracture points  20  provided as detachment points and embodied in the form of acute-angled notches  21 , as shown with particular clarity in the enlarged depiction in  FIG. 5 , and the closed bearing race  19  whose circumferential shape corresponds to that of the bearing socket  18  has only a relatively small wall thickness remaining at the bottom of the notch. The notch angle in the depiction in  FIG. 4  is preferably approximately 60 to 80° . 
     If such an embodiment of desired fracture points  20  by means of wedge-shaped notches  21  that significantly reduce the wall thickness of the bearing race  19  or in the form of channel-shaped, rounded, or groove-shaped rectangular recesses leads to difficulties in producing the bearing race  19 , which can be the case particularly if the bearing race  19  is produced by casting or sintering, then according to the invention, the circumference region on the other side from the recess of each notch  21 , which is in particular wedge-shaped, can be provided with a thickened region  23  as shown in  FIG. 6  so that in the region of the notches  21  as well, the thickened region  23  initially provides a wall cross section that corresponds to the wall thickness of the rest of the bearing race  19 . The thickened region  23  whose removal is required for insertion into the bearing socket  18  can then be abraded away, for example by means of grinding, stripping, or the like so that with this production-dictated embodiment of the still-closed bearing race  19 , once the thickened region  23  is abraded away, the bearing race  19  can be inserted into the bearing socket  18  in the above-described way. 
     Basically, it is also possible to abrade away the thickened region  23  only in the region coinciding with the circumference region to be broken out and thus to embody projections in the transition from the cut-out circumference region  22  on the bearing race  19 , which projections, by engaging radially over or in the bearing socket  18 , assure a rotational fixing of the bearing race  19 . 
     Such a rotational fixing can also be achieved in a different way, for example according to  FIG. 7 , by means of recesses  24  on the end surface of the bearing race  19 , for which corresponding counterpart elements, not shown, are provided on the bearing socket. 
     The foregoing relates to the preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.