Abstract:
The present disclosure relates to an expandable reamer having a base body, a ring section, at least one cutting edge which is geometrically defined and provided on the outer surface of the ring section, an adjustment device which works on the ring section from the inside, has an adjustment screw, and serves to adjust the radial position of the at least one cutting edge, wherein the adjustment device is arranged in a cavity provided in the base body of the expandable reamer, and an adjustment body with a conical or round outer surface. The adjustment body can be displaced in the direction of the central axis of the expandable reamer and serves for the expansion of the ring section. The expandable reamer is characterized in that the adjustment body is designed as an adjustment sleeve which surrounds the adjustment screw and is mounted in a floating manner.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a 35 U.S.C. §371 National Phase conversion of PCT/EP2008/004894, filed Jun. 18, 2008, which claims benefit of German Application No. 10 2007 028 167.8, filed Jun. 20, 2007, the disclosure of which is incorporated herein by reference. The PCT International Application was published in the German language. 
     TECHNICAL FIELD 
     The invention relates to an expandable reamer The expanding reamer is an expandable reamer. 
     BACKGROUND 
     Expanding reamers of the type which are here discussed are known. They have a basic element, as well as an annular portion on whose outer face there is defined at least one geometrically defined cutting edge. The radial position of the at least one cutting edge is adjusted by means of an adjusting device comprising an adjusting screw. For this purpose, an adjusting element of the adjusting device, having a conical or spherical outer face, is moved with the aid of the adjusting screw in the direction of the center axis of the expanding reamer, so that it widens the annular portion to a greater or lesser extent. It has been shown that the adjusting element of the adjusting device is subjected to high wear and that an exact positioning of the at least one cutting edge often fails, because the position of the adjusting element is dependent on the position of the thread in the basic element in which the adjusting screw engages. The thread is frequently not exactly concentric to the center axis of the expanding reamer, so that the radius of the at least one cutting edge is not precisely adjustable. If the expanding reamer has a plurality of geometrically defined cutting edges, it is in many cases not possible to adjust these such that they lie exactly on the same orbit. 
     SUMMARY 
     The object of the invention is therefore to provide an expanding reamer which does not have these said drawbacks. 
     In order to achieve this object, an expanding reamer is proposed which comprises the features stated in Claim  1 . It is characterized in that the adjusting element is not an integral component part of the adjusting screw, but rather is configured as an adjusting sleeve which encompasses the adjusting screw and is mounted floatingly thereon. By the term “floating” is conveyed that the adjusting sleeve is displaceable both in the axial and in the radial direction relative to the adjusting screw and can thus perform compensating motions. It thus comes to bear optimally from inside against the annular portion of the expanding reamer, so that the at least one geometrically defined cutting edge is very precisely adjustable. The floating mounting of the adjusting sleeve on the adjusting screw means that when the adjusting screw is rotated, i.e. is turned to adjust the radial position of the at least one cutting edge, the adjusting sleeve remains rotationally fixed in the annular portion and is thus subjected to reduced wear. 
     A preferred illustrative embodiment is characterized in that the adjusting screw has at one end an external thread and at its other end a head, which latter, on its side facing the thread, has a contact surface. This is borne against by the adjusting sleeve, which, upon an appropriate rotary motion of the screw in the direction of its rotational axis, i.e. in the direction of the center axis of the expanding reamer, can be displaced such that the annular portion with the at least one cutting edge is widened. The adjusting element is thus part of a wedge gear, which, upon appropriate axial displacement of the adjusting sleeve, effects a widening of the annular portion and thus for the positioning of the at least one cutting edge. 
     In a further preferred illustrative embodiment, it is provided that the adjusting device has an extraction device, which serves, when the adjusting screw is loosened, to apply an axial force to the adjusting sleeve in order to extract this from the expanding reamer. It is thus possible to configure the adjusting device as a structural unit, which can be inserted into the expanding reamer and can be removed from this without difficulty. 
     Further embodiments emerge from the remaining sub-claims. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The invention is explained in greater detail below with reference to the figures: 
         FIG. 1  shows a basic diagram of the front part of a first illustrative embodiment of an expanding reamer in longitudinal section; 
         FIG. 2  shows an exploded representation of the adjusting device of the expanding reamer, which is visible from  FIG. 1 ; 
         FIG. 3  shows a front view of the expanding reamer according to  FIG. 1 , without adjusting device, and 
         FIG. 4  shows a partially cut-open side view of a second illustrative embodiment of an expanding reamer. 
     
    
    
     DETAILED DESCRIPTION 
     From  FIG. 1 , the front part of a first illustrative embodiment of an expanding reamer  1  is visible. Its left end is broken off and can be configured in any chosen known manner and can have a mounting shaft with which the expanding reamer  1  can be attached in a rotationally fixed manner directly to a machine tool, or else to an intermediate piece, adapter or the like. The expanding reamer  1  has a basic element  3 , in which from the right, i.e. from an end face  5 , a cavity  7  is made. 
     In a region of the basic element  3  close to the end face  5 , i.e. in an annular portion R, the expanding reamer  1  is provided with at least one geometrically defined cutting edge. In the illustrative embodiment represented here, four cutting inserts, arranged in pairs one opposite the other, are apparent, namely an upper cutting insert  9  and a lower cutting insert  11 . The cutting inserts have, at their end facing the end face  5 , geometrically defined cutting edges  13  and  15 . In principle, it is possible to configure the cutting edges directly on the basic element  3  of the expanding reamer  1 . Preferably, however, cutting inserts are inserted as known into the basic element  3 , which cutting inserts can be formed from a particularly hard-wearing material, particularly in the region of the geometrically defined cutting edges. 
     The cutting edges  13  and  15  remove chips from a bore surface, generally by the expanding reamer  1  being set in rotation, while the workpiece stands still. It is also conceivable, however, to rotate the workpiece while the expanding reamer  1  remains fixed. Only a relative rotary motion between the cutting edges and the bore surface is critical. 
     In the basic element  3 , in the region of the cutting inserts  5 , chip spaces  17  and  19  are provided, which serve to carry off chips removed by the cutting edges  13  and  15  in order to prevent these from impairing the bore surface. 
     The cavity  7  serves to receive an adjusting device  21  comprising an adjusting screw  23 , referred to as a setscrew, an adjusting element, which is preferably configured as an adjusting sleeve  25  encompassing the adjusting screw  23 , and an extraction device  27 . 
     The adjusting screw  23  has at its first end  29  an external thread  31 , which cooperates with an internal thread  33 . The latter is made in the wall of a bore  35 , which extends from the floor  37  of the cavity  7  further inward into the basic element  3  of the expanding reamer  1 . The cavity  7 , the bore  35  and the adjusting screw  23  are arranged concentric to a center axis  39 , referred to as the rotational axis, of the expanding reamer  1 . 
     At the second end  41  of the adjusting screw  23 , which second end lies opposite the first end  29 , a head  43  is provided, the external diameter of which is larger than that of the shaft  45  of the adjusting screw  23 , which shaft is provided with the external thread  31 . On the head  43  a contact surface  47  is hence formed, which points toward the first end  29  of the adjusting screw  23  and is borne against by the—in FIG.  1 —right end of the adjusting sleeve  25 , i.e. the axial end face thereof. 
     The outer face  49  of the adjusting sleeve  25  is conically or spherically configured. It has a first region which bears against the contact surface  47  and the external diameter of which is larger than the internal diameter of the cavity  7 . The opposite, left end of the adjusting sleeve  25  has an external diameter which is smaller than the internal diameter of the cavity  7 , so that the adjusting sleeve  25  can engage in the cavity  7 . 
     The inner face  51  of the cavity  7  can be cylindrically configured up to the end. Preferably, however, it is made to be conically or spherically configured close to the end face  5 , so that it bears in an annular region  53  against the outside of the adjusting sleeve  25 . Depending on the design of the region of the inner face  51  close to the end face  5 , this annular region  53  lies more or less far inside the cavity  7  at a distance from the end face  5 . 
     The cutting edges of the expanding reamer  1 , which are here configured as cutting edges  13  and  15  of the cutting inserts  9  and  11 , thus lie in an annular region  53  of the expanding reamer  1 , which annular region can be widened more or less extensively by the adjusting device  21  in order to adjust and set the radial position of the cutting edges  13  and  15 . The annular region  53  here lies in the front portion, facing the end face  5 , of the annular portion R. 
     Between the inner face  51  of the cavity  7  and the outer face  59  of the adjusting sleeve, a wedge gear is therefore configured, with the aid of which an axial motion of the adjusting sleeve  25  in the direction of the center axis  39  is converted into a more or less wide radial widening of the annular region  53  so as to realize a radial positioning of the cutting edges  13  and  15  in relation to the center axis  39 . 
     The basic working of such a wedge gear is known. It is therefore clear that the outer face  49  of the adjusting sleeve  25  is preferably of conical or wedge-shaped configuration, while the inner face  51  of the cavity  7 , in the region of contact with the outer face  49 , is preferably of spherical configuration, i.e.—viewed in cross section—has a radius and widens in the direction of the end face  5 . 
     The inner face  55  of the adjusting sleeve  25  has an internal diameter which is somewhat larger than the external diameter of the shaft  45  of the adjusting screw  23 . The adjusting sleeve  25  is thus movable on the shaft  45  in the axial direction of the adjusting screw  23 , i.e. in the direction of the center axis  39 , but also, in particular, in the radial direction to the center axis  39 . Should the bore  35 , therefore, not run exactly concentric to the center axis  39 , the adjusting sleeve  25  can nevertheless align itself on the inner face  51  of the cavity  7  and thus ensure an optimal setting of the at least one cutting insert. 
     Since the adjusting sleeve  25  is configured separate from the adjusting screw  23 , the material properties can also be freely chosen so as to influence the sliding properties of the adjusting sleeve  25  in relation to the inner face  51  of the cavity  7 , but also of the adjusting sleeve  25  in relation to the contact surface  47 . 
     The adjusting device  21  has, as stated, an extraction device  27 . This serves to be able to remove the adjusting sleeve  25  easily from the cavity  7  when the adjusting screw  23  is loosened. The extraction device  27  is enclosed by the adjusting sleeve  25  in the cavity  7 , which extraction device is thus situated to the left of the adjusting sleeve  25  in the cavity  7 . When the adjusting screw  23  is moved outward from the cavity  7 , i.e. to the right in  FIG. 1 , the extraction device  27  takes with it the adjusting sleeve  25 . 
     The extraction device  27  can, as here, be configured as a threaded sleeve, which is screwed onto the shaft  25  of the adjusting screw  23  and is arranged at a suitable distance—measured in the direction of the center axis  39 —from the adjusting sleeve  25 . If it has the desired relative position to the adjusting sleeve  25 , the threaded sleeve is fixed in a suitable manner on the shaft  45 , for example by gluing, soldering, welding, or else also by deformation. When the adjusting screw  23  is unscrewed, the threaded sleeve can thus no longer be displaced on the shaft  45  and pulls the adjusting sleeve  25  out of the interior  7 . 
     It will be clear that, instead of the threaded sleeve, a pin running transversely to the shaft  45 , or else also an annular collar, can be provided, the external diameter of which is dimensioned such that it butts against the left end of the adjusting sleeve  25  when the adjusting screw  25  is unscrewed from the basic element  3  of the expanding reamer  1 . Thus the ring collar, too, as also a corresponding pin, pulls the adjusting sleeve  25  out of the cavity  7 . 
     The adjusting device  21  thus preferably forms an assembly unit, which can be easily inserted into and removed from an expanding reamer  1 . 
     Adjusting sleeves  25  matched to the inner face  51  of the cavity  7  and having a more or less steep apex angle of the outer face  49  can thus be provided, which are respectively inserted into an expanding reamer  1  in order to achieve a specific adjusting behavior, i.e. a specific gear ratio of the bevel gear. 
     From the representation according to  FIG. 1 , it can be seen that the adjusting device  21  is very compact and can be used even in expanding reamers  1  with very small diameter. Thus, even expanding reamers with a machining diameter of 5 mm and less can be combined with an adjusting device  21  of the type here discussed. In this context, the adjusting behavior of the adjusting device  21  can be influenced by the design of that region of the inner face  51  of the cavity  7  which borders the end face  5 , in particular of the annular region  53  cooperating with the adjusting sleeve  25 , and the outer face  49  of the adjusting sleeve  25 . It is thus possible to realize an adjusting sleeve  25  with a very shallow-angled outer face  49 , so that an axial adjusting motion of the adjusting sleeve  25  leads only to a very small radial widening of the annular region  53 . The expanding reamer  1  can thus be very sensitively adjusted. 
       FIG. 2  shows the adjusting device  21  visible from  FIG. 1  in exploded representation, in order that the individual parts thereof once again become clearly apparent. Identical parts are provided with identical reference numerals, so that, in this respect, reference is made to the description to  FIG. 1 . 
     The adjusting device  21  thus has an adjusting screw  23  provided with a head  43  and a shaft  45 . At least at that first end  29  of the adjusting screw  23  lying opposite the head  23 , an external thread  31  is provided. It must extend sufficiently far to the right in the direction of the second end  41  of the shaft  45  that the extraction device  27 , which is here configured as a threaded sleeve and is provided with an internal thread  57  mating with the external thread  31 , can be screwed correspondingly far onto the shaft  45 , as can be seen from  FIG. 1 . The internal diameter of the inner face of the adjusting sleeve  25  is modeled on the external diameter of the shaft  45  of the adjusting screw  23  in such a way that the adjusting sleeve  25  can be easily slid onto the adjusting screw  23  and has radial play relative to the shaft  45  thereof. A mispositioning of the adjusting screw  23  does not therefore readily lead to an influencing of the adjusting sleeve  25 , so that the latter can ensure a very exact adjustment of the at least one cutting edge, here the cutting edges  13  and  15 , so that these lie on a common orbit. 
       FIG. 3  shows the expanding reamer  1  in front view, i.e. a top view of the end face  5  represented in  FIG. 1 . Inserted in the basic element  3  are at least one, here four cutting inserts, of which the cutting inserts  9  and  11  were visible in  FIG. 1 . The cutting edges  9 ′ and  11 ′, which are correspondingly offset by about 90°, are identically configured, so that there is nothing further to be stated in this regard. 
     The cutting inserts  9 ,  9 ′,  11  and  11 ′ are inserted in recesses  59 ,  61 ,  59 ′ and  61 ′ made in the basic element  3  of the expanding reamer  1 , so that in front of the cutting edges  9 ,  11 ,  9 ′,  11 ′, in the rotational direction represented by an arrow  63 , a chip space is respectively obtained, via which chips removed from the cutting edges  13 ,  15 ,  13 ′,  15 ′ can be transported away via the chip space. 
     From  FIG. 3  it can further be seen that in the end face  5  of the basic element  3  of the expanding reamer  1  a cavity  7  is made. A double line indicates that the inner face of the cavity  7  merges via a conically or spherically configured transition region  65  into the end face  5 . It is also clearly apparent that in the floor  37  of the cavity  7  a bore  35  is made, comprising an internal thread  33  in which the adjusting screw  23  engages. 
     The end face according to  FIG. 3  also shows that the expanding reamer  1  is provided with four cutting edges  13 ,  15 ,  13 ′,  15 ′, which—viewed in the peripheral direction—are arranged at an approximately equal distance apart. 
     It is possible in principle to provide the expanding reamer  1  with at least one cutting edge. Two or three cutting edges can also be provided. The expanding reamer  1  is supported particularly evenly in a bore to be machined, if six cutting edges are provided. 
     In an expanding reamer  1  intended for the machining of bores with small internal diameter, four cutting edges are preferably provided in order that the basic element  3  is not overly weakened and thus particularly small machining diameters can be realized. 
     A second illustrative embodiment of an expanding reamer is obtained from  FIG. 4 , which portrays the expanding reamer  1  in side view, the side wall being partially cut open. Identical and functionally identical parts are provided with identical reference numerals, so that, in this respect, reference is made to the description of the preceding figures. 
     The illustrative embodiment of the expanding reamer  1  which can be seen from  FIG. 4  differs from that represented in the preceding figures by the fact that the internal diameter of the cavity  7  is chosen such that it can receive an adjusting element, which here is likewise configured as an adjusting sleeve  25 ′. The adjusting sleeve  25 ′ is here dimensioned such that its inner face  55  does not touch the outer face of the head  43  of the adjusting screw  23 . The adjusting sleeve  25 ′ thus here receives not only the shaft  45 , but also the head  43  of the adjusting screw  23 . The adjusting sleeve  25 ′ in this case has an outer wall  67 , which surrounds the head  43  of the adjusting screw  23 . The outer wall  67  merges into a floor  69  of the adjusting sleeve  25 ′, which forms a supporting surface  71  for the bearing surface  47  of the head  43  of the adjusting screw  23 . 
     The space enclosed by the outer wall  67  is dimensioned such that it receives the head  43  of the adjusting screw—preferably in full; it is thus preferably arranged recessed in the adjusting sleeve  25 ′. 
     The floor  69  is provided with a through hole  73 , the center axis of which coincides with the center axis  39  of the expanding reamer  1 . The internal diameter of the through hole  73  is chosen such that the floor  69  does not touch the outer face of the shaft  45 , and the adjusting sleeve  25 ′, like the adjusting sleeve  25  of the illustrative embodiment of the expanding reamer represented in  FIGS. 1 to 3 , is mounted floatingly on the adjusting screw  23 . The adjusting sleeve  25 ′ is thus movable on the shaft  45  in the axial direction of the adjusting screw, i.e. in the direction of the center axis  39 , but also, in particular, in the radial direction to the center axis  39 . Should the through hole  73 , therefore, not run exactly concentric to the center axis  39 , then the adjusting sleeve  25 ′ can nevertheless align itself on the inner face  51  of the cavity  7 . Hence, an optimal setting of the at least one cutting insert of the expanding reamer  1  is here too ensured. 
     While therefore the head  43  of the adjusting screw  23  rests on an annular face of the adjusting sleeve  25  in the illustrative embodiment according to  FIGS. 1 to 3 , the adjusting screw  23  engages inside the adjusting sleeve  25 ′ in such a way that also the head  43  of the adjusting screw  23  is received by the adjusting sleeve  25  and rests with its contact surface  47  inside the adjusting sleeve  25 ′ on the supporting surface  71  of the adjusting sleeve  25 ′. The contact surface  47  thus cooperates with a supporting surface  71  provided inside the adjusting sleeve  25 ′. 
     The adjusting screw  23 , just like the adjusting sleeve  25 ′, can thus be accommodated recessed in the end face  5  of the expanding reamer  1 , so that this can be used also to machine bottomed bores or blind holes, i.e. bores which are not configured as a through hole, but instead have a floor. 
     The outer face  49  of the adjusting sleeve  25 ′, as in the first illustrative embodiment, is conically configured and cooperates with the inner face  51  of the cavity  7 , which, as described above, can be spherically configured in an annular region  53 . 
     Here, as in the first illustrative embodiment, it is also possible to configure the outer face  49  of the adjusting sleeve  25 ′ spherically and the inner face  51  of the cavity  7  conically. In both cases, a wedge gear is realized. If the adjusting sleeve  25 ′ is moved—to the left in FIG.  4 —into the cavity  7 , then the annular portion R is radially widened. This leads to a radial adjustment of the cutting edges of the expanding reamer  1 , of which, in  FIG. 4 , the cutting edges  13  and  15  can be seen. 
     While in the first illustrative embodiment the adjusting sleeve  25 , on an axial end face configured as an annular surface, is subjected to a force via the contact surface  47  of the adjusting screw  23 , in the second illustrative embodiment according to  FIG. 4  it is provided that the adjusting forces of the adjusting screw  23  act upon the floor  69  of the adjusting sleeve  25 ′. For this purpose, the bearing surface  47  of the head  43  of the adjusting screw  23  rests on the floor  69 , namely on its supporting surface  71 . If the adjusting screw  23  is screwed into the basic element  3  of the expanding reamer  1 , i.e. is moved to the left in  FIG. 4 , then the adjusting sleeve  25 ′ is pulled and not, as in the first illustrative embodiment, pushed inside the cavity  7 . 
     From  FIG. 4  it becomes clear that the floor  69  of the adjusting sleeve  25 ′ is preferably arranged at a greater distance from the end face  5  of the expanding reamer than the annular region  53  acted upon by the adjusting forces of the adjusting sleeve  25 ′. The force transmission of the adjusting screw  23  thus lies in  FIG. 4  also to the left of the annular region  53  of the annular portion R. 
     This results, if the adjusting sleeve  25 ′ is pulled into the cavity  7  in the setting of the cutting edges of the expanding reamer  1 , in the achievement of more precise setting results than is the case in the illustrative embodiment according to  FIGS. 1 to 3 . 
     As can be seen from  FIG. 4 , the adjusting device  21  can here too comprise an extraction device  47  on the shaft  45  of the adjusting screw  23 , with the aid of which the adjusting sleeve  25 ′, when the adjusting screw  23  is loosened, can be pulled out of the cavity  7  of the expanding reamer  1 . That which has been stated about the extraction device  47  of the first illustrative embodiment of the expanding reamer  1  applies here correspondingly. 
     Here too, the adjusting device  21  can be realized as a prefabricated assembly unit, which comprises the adjusting screw  23 , the adjusting element configured as an adjusting sleeve  25 ′, and the extraction device  27 . The above-described advantages are thus obtained, namely the facility to combine a variety of adjusting devices  21  with different expanding reamers  1 .