Patent Publication Number: US-10759038-B2

Title: Hand-held machine tool having a tool-change magazine

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hand-held machine tool having a tool receiver to receive an insert tool provided with an external profile, the tool receiver featuring an internal receiver provided at least sectionally with an internal profile, and having a tool housing which is assigned a tool-change magazine having at least one tool chamber for storing the insert tool, the tool chamber being alignable with the tool receiver in order to allow the insert tool to be transferred from the tool chamber into the internal receiver or from the internal receiver into the tool chamber, a positioning device being provided for the circumferential alignment of the external profile when transferring the insert tool from the tool chamber into the internal receiver of the tool receiver in order to produce a form-locking connection between the internal profile and the external profile that at least for the most part, is free of rotational play. 
     BACKGROUND INFORMATION 
     Hand-guided screwdrivers are believed to be understood from the related art, having an integrated, e.g., drum-like bit magazine for keeping a larger number of different screwdriver bits ready. Such screwdrivers have a rotationally driven tool receiver for receiving the screwdriver bits stored in the bit magazine, the screwdriver bits being provided in each case with an external hexagon, for example. In order—as independently of a specific rotational position of the tool receiver as possible—to be able to insert a corresponding external hexagon of a rotational entrainment of a screwdriver bit to be supplied from the bit magazine to the tool receiver, into the tool receiver in a manner free of tilt, i.e., free of resistance, by a purely translatory shifting movement on the part of the user, the tool receiver of the screwdriver is furnished with a rotational entrainer profile provided with multiple longitudinal ribs. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a hand-held machine tool having a tool receiver to receive an insert tool provided with an external profile, the tool receiver featuring an internal receiver provided at least sectionally with an internal profile, and having a tool housing which is assigned a tool-change magazine having at least one tool chamber for storing the insert tool, the tool chamber being alignable with the tool receiver in order to allow the insert tool to be transferred from the tool chamber into the internal receiver or from the internal receiver into the tool chamber. A positioning device is provided for the circumferential alignment of the external profile when transferring the insert tool from the tool chamber into the internal receiver of the tool receiver in order to produce a form-locking connection between the internal profile and the external profile that at least for the most part, is free of rotational play. The positioning device has at least one magnet which is provided to align the insert tool relative to the internal profile upon insertion of the insert tool into the internal receiver. 
     An unfailingly tilt-free, resistance-free insertion of the insert tool into the tool receiver is thus ensured, regardless of its circumferential starting position within the tool chamber. Therefore, a seating of the screwdriver bit in the tool receiver that is marked by rotational play which, among other things, reduces the perceived quality of the screwdriver, may at least for the most part be prevented. Moreover, an undesirable limitation of a maximum torque transferable between the tool receiver and a corresponding screwdriver bit may be increased, and because of the form-locking connection that is at least substantially free of rotational play, a time lag when changing the direction of rotation of the insert tool may effectively be prevented. In addition, owing to the magnet, the circumferential alignment of an insert tool is accomplished without mechanically moving components such as spring elements or the like. To this end, the insert tool may be formed with a magnetic material. 
     According to one specific embodiment, the external profile of the insert tool is an external polygon and the internal profile of the internal receiver is an internal polygon. The external polygon may be an external hexagon and the internal polygon is an internal hexagon. 
     Consequently, a large number of standardized insert tools customary in the marketplace like, for example, familiar screwdriver bits or the like, may be used. 
     The internal polygon may be formed at least sectionally in a sleeve-like tool-receiver section of the tool receiver, and the at least one magnet of the positioning device is disposed in the sleeve-like tool-receiver section. 
     Thus, reliable circumferential tilting of the insert tool into the correct insertion position is already provided. 
     The internal polygon may have a centering section. 
     The insert tool is thereby centered radially upon insertion into the tool receiver. 
     In a further technically advantageous development, when the insert tool is in the at least partially inserted state, at least one radially inwardly directed magnetic surface of the at least one magnet and at least one polygon surface of the external polygon lie side by side in parallel, at least in some areas. 
     Because of this circumstance, the insertion position, once reached with the aid of the magnetic positioning device, is maintained permanently, regardless of changes in the position of the hand-held machine tool, vibrations or the like. 
     The at least one magnetic surface and the at least one polygon surface of the external polygon of the insert tool may be offset circumferentially by a maximum of 20° relative to each other when the polygon surface reaches the at least one magnet. 
     Reliable tilting of the insert tool about its longitudinal central axis is thereby ensured. 
     The at least one magnetic surface and the at least one polygon surface of the external polygon of the insert tool may be set apart from each other by a maximum of 2 mm. 
     Reliable tilting of the insert tool about its longitudinal central axis is ensured as a result of this, as well. 
     According to one further development, the positioning device has at least one further magnet which, in relation to a longitudinal central axis of the insert tool, is offset by an angle not equal to 60° or not equal to a multiple of 60° relative to the at least one magnet. 
     Tilting of the insert tool about its longitudinal central axis may thus be further optimized. 
     In one embodiment, the at least one magnet of the positioning device is formed by a permanent magnet or by a magnetized area of the sleeve-like tool-receiver section. 
     The magnet is thereby integrated into the hand-held machine tool especially easily from the standpoint of manufacturing technology. 
     The insert tool may be transferable out of the tool chamber into the internal receiver of the tool receiver and out of the internal receiver back into the tool chamber with the aid of a transfer mechanism, especially a push bar. 
     As a result, the tool-change mechanism is operable intuitively for an operator. 
     One free end section of the push bar facing the insert tool may be magnetized. 
     Thus, a reliable axial coupling is provided between the insert tool and the push bar which, however, is easily releasable again if necessary. 
     The at least one magnet may be provided to rotate the insert tool about a longitudinal central axis of the insert tool in such a way that, upon insertion of the insert tool into the internal receiver, the cross-section of the external profile of the insert tool is located completely within the internal profile of the internal receiver. 
     The process of transferring the insert tool from the tool chamber into the tool receiver may thus be further improved. 
     The present invention is explained in greater detail in the following description on the basis of exemplary embodiments shown in the drawing. Identical or identically acting components are provided here with the same reference numerals and in each case are described only once. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a schematic, partial cutaway side view of a hand-held machine tool having a tool-change magazine and a tool receiver according to one specific embodiment. 
         FIG. 2  shows a partial cutaway side view of the tool receiver from  FIG. 1  according to one specific embodiment. 
         FIG. 3  shows a sectional view of the tool receiver from  FIG. 2  with the insert tool from  FIG. 1  positioned in it. 
         FIG. 4  shows an enlarged perspective view of a segment IV from  FIG. 2 . 
         FIG. 5  shows the tool receiver from  FIG. 4  with a push bar as transfer mechanism. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows as example a machine tool  100  able to be guided manually and powered by motor, also referred to hereinafter as “hand-held machine tool.” It may have a tool housing  111 , in which a tool-change magazine  120  is disposed. According to one specific embodiment, tool-change magazine  120  is drum-like and is rotatable about an axis of rotation  103 . Illustratively, tool-change magazine  120  is in the form of a hollow cylinder having a ring-like casing body  102 , in which a plurality of tool chambers is provided. For example, insert tools may be disposed in the tool chambers, it being possible, for instance, to provide different insert tools in all tool chambers. For the purpose of clarity and simplicity of the drawing, only one tool chamber is indicated in  FIG. 1  and identified by reference numeral  199 . Disposed as illustration in this tool chamber  199  is an insert tool  101  that is exemplified here as a screwdriver bit. 
     Hand-held machine tool  100  is formed illustratively in the manner of what is referred to as a bit screwdriver for the comfortable handling of so-called “screwdriver bits.” However, it is pointed out that the present invention is not limited to such bit screwdrivers, but rather may be used for all machine tools in which a tool-change magazine, especially a drum-like tool-change magazine rotatable about a longitudinal axis, is able to be used, regardless of whether screwdriver bits or other interchangeable objects are stored in the tool-change magazine, or whether or not the machine tool is able to be held or guided manually. 
     A tool receiver  200  for receiving insert tool  101  is disposed illustratively on tool housing  111 , tool receiver  200  being rotatable about an assigned axis of rotation  188  or a longitudinal central axis. In order to drive insert tool  101 , tool receiver  200  is coupled illustratively via a gear toothing  106  to an output shaft  119  of a gear unit  112  that is disposed, by way of example, in a gear housing  114 . To that end, provided as illustration on output shaft  119  is a driving gear wheel  179  which interacts in gear toothing  106  with an output gear wheel  202  provided on tool receiver  200 . For instance, output shaft  119  is driven rotationally by a motor shaft  177  of a drive motor  107  that is coupled to gear unit  112  and is disposed, e.g., in an assigned motor housing  117 , motor housing  117  and gear housing  114  being mounted and secured in tool housing  111 , for example. 
     Among other things, tool receiver  200  has an internal receiver  210  provided with an internal profile  152 . By way of example, internal profile  152  of internal receiver  210  is an internal polygon  153 , and an external profile  151  of insert tool  101  is realized by an exemplary external polygon  154  that corresponds to internal polygon  153  and is axially symmetrical with respect to a longitudinal central axis  189  of insert tool  101 . Internal polygon  153  may be an internal hexagon, whose center axis corresponds to axis of rotation  188 , and is therefore also referred to hereinafter as “internal hexagon  153 ,” while external polygon  154  may be an external hexagon, and is therefore also referred to hereinafter as “external hexagon  154 .” 
     Internal hexagon  153  may be located at least sectionally in a sleeve-like tool-receiver section  211  of internal receiver  210 , into which external hexagon  154  of insert tool  101  is insertable axially upon transferring it from tool chamber  199  in order to produce a form-locking connection with tool receiver  200  that may be essentially free of rotational play. To that end, tool chamber  199  may be oriented in stay-put fashion in such a way that rotational or center axis  188  is in alignment with longitudinal central axis  189  of insert tool  101 . 
     In order to slip insert tool  101  out of tool chamber  199  into internal receiver  210  of tool receiver  200  and to slip it out of internal receiver  210  into tool chamber  199 , a transfer mechanism  110  is provided. It has a transfer element  108  formed, for example, in the manner of a push bar  109  operable via an operating element  122 . For instance, push bar  109  is guided axially in a guideway  116  provided on gear housing  114  (compare especially  FIG. 5 ). At its axial end facing insert tool  101 , push bar  109  may be magnetized for the magnetic connection with insert tool  101 . For this purpose, operating element  122  may be displaceable axially in an opening  113 , provided on tool housing  111 , parallel to axis of rotation  188  of tool receiver  200  and of longitudinal central axis  189  of insert tool  101 , respectively. As an alternative, however, a non-parallel displaceability may also be realized. 
     When changing a tool in hand-held machine tool  100 , tool-change magazine  120  may be rotated about axis of rotation  103  into a tool-change position in which, for example, tool chamber  199  with insert tool  101  is in alignment with tool receiver  200  or, more specifically, with its internal receiver  210 . Operating element  122  is then shifted in the direction of an arrow  167  in opening  113  from its rear axial end position in  FIG. 1  up to a front axial end position, in which push bar  109  passes through tool chamber  199  and locks insert tool  101  in internal receiver  210  of tool receiver  200 . To transfer tool  101  out of tool receiver  200  into tool chamber  199 , operating element  122  is then shifted axially in opening  113  in a direction opposite to arrow  167 , back into its rear axial end position. 
     However, it should be pointed out that the fundamental operating principle and the configuration of hand-held machine tool  100  are already known from the German Patent DE 10 2006 059 688 A1, which in addition, for example, describes adjusting means for rotating tool-change magazine  120  about axis of rotation  103 , in order to facilitate alignment of tool chamber  199  with tool receiver  200 . Therefore, the disclosure of DE 10 2006 059 688 A1 is incorporated explicitly into the present description, in order to simplify it. 
       FIG. 2  shows tool receiver  200  from  FIG. 1  upon the transfer of insert tool  101  in the direction of an arrow  267  into tool receiver  200  rotatable about axis of rotation  188  and longitudinal central axis  189 , respectively, and having sleeve-like tool-receiver section  211 . Illustratively, at a first axial end section  201 , tool receiver  200  has output gear wheel  202  from  FIG. 1 , while internal hexagon  153  of internal profile  152  of internal receiver  210  is located at an opposite second axial end section  203 , internal hexagon  153  may be used for the accommodation, essentially free of rotational play, of external profile  151  of insert tool  101  implemented as external hexagon  154 . 
     In the area of a first shoulder  217  of output gear wheel  202 , tool receiver  200  may change over into a first tapered area  216 , which may at a second shoulder  215 , changes into tool-receiver section  211 . Mounted illustratively on tool-receiver section  211  is a roller bearing  270 , formed in the manner of a needle roller bearing, for the rotationally movable support of tool receiver  200  in tool housing  111  (see  FIG. 1 ). For example, roller bearing  270  is fixed in position in axially immovable manner between first tapered area  216  and a locking disk  260 . On its part, locking disk  260  is blocked in the axial direction of tool receiver  200  by a retaining ring  250 , e.g., a C-clip, which may be secured in an annular groove  214  formed on tool-receiver section  211 . 
     Internal hexagon  153  of internal profile  152  of internal receiver  210  may have a centering section  156  directed away from second axial end section  203  and beveled illustratively in conical or wedge-shaped fashion. Centering section  156  may be used for the radial centering of insert tool  101  upon its insertion into tool receiver  200 . 
     In an axial area between retaining ring  250  and centering section  156 , sleeve-like tool-receiver section  211  has a magnetic positioning device  300 , which is used for the circumferential alignment of external profile  151  of insert tool  101  upon its transfer into internal receiver  210 , creating a form-locking connection, which may be essentially free of rotational play, between internal profile  152 , or rather internal hexagon  153  and external profile  151 , or rather external hexagon  154 . For this purpose, positioning device  300  may have at least one magnet  310 , which is provided to align insert tool  101  relative to internal profile  152  during its insertion into internal receiver  210 . The at least one magnet  310  may be provided to rotate insert tool  101  about its longitudinal central axis  189 , in each case to the extent that upon axial insertion of insert tool  101  into internal receiver  210 , a cross-section of external profile  151  of insert tool  101  lies completely within internal profile  152  or is congruent with it. In the state in which insert tool  101  is inserted at least partially into internal receiver  210  (see especially  FIG. 3 ), at least one radially inwardly directed magnetic surface  312  and at least one hexagon surface  158  of insert tool  101  may lie close to one another, at least in some areas. 
     It should be pointed out that centering section  156  is merely optional, so that in an alternative realization, it is possible to dispense with provision of this centering section  156 . For example, this is the case in the event that the at least one magnet  310  is positioned sufficiently precisely in sleeve-like tool-receiver section  211 . 
     Magnetic surface  312 , which runs parallel to axis of rotation  188  and longitudinal central axis  189 , respectively, and may be planar, and hexagon surface  158  may be apart from each other here by a radial distance  314  of a maximum of 2 mm in order, inter alia, to reliably ensure adequate action of force of magnet  310  on insert tool  101 . Upon the axial approach to magnet  310 , the one magnetic surface  312  and the at least one hexagon surface  158  of external hexagon  154  of insert tool  101  may be offset circumferentially by a maximum of 20° relative to each other. In addition, magnet  310  may have a centering surface  316 , running at an angle here of, e.g., approximately 45° in relation to axis of rotation  188  and longitudinal central axis  189 , respectively, which is facing in the direction of first axial end section  201  and therefore further facilitates the axial insertion of insert tool  101  into tool receiver  200 . 
     In addition, positioning device  300  may have one or more further magnets  320  which, in relation to axis of rotation  188  or longitudinal central axis  189  of tool receiver  200 , is/are offset circumferentially relative to magnet  310  by an angle ß, only indicated graphically, which may be not equal to 60° or not equal to a multiple thereof. Moreover, positioning device  300  may have at least one further, axially displaceable magnet  325  to further optimize the process of inserting insert tool  101  into tool receiver  200 . This axially displaceable magnet  325  may be movable in the axial direction of tool receiver  200  at least for a short distance  190  together with insert tool  101  to be inserted into tool receiver  200 , so that the correct circumferential position of insert tool  101  in relation to internal receiver  210  is maintained for a longer movement range. 
     Magnets  310 ,  320 ,  325  may be formed by permanent magnets as separate components and/or integrally with magnetized areas of sleeve-like tool-receiver section  211 , provided it is produced with a ferromagnetic material. The permanent magnets may be produced with rare-earth elements by sintering, etc. One magnetized area  335  of the magnetized areas or zones is denoted representatively for all the rest. 
       FIG. 3  shows tool receiver  200  from  FIG. 2  with insert tool  101  from  FIG. 1  positioned in it after the complete axial insertion of insert tool  101  into internal receiver  210  of tool receiver  200 . In this completely inserted state, external profile  151 , or more precisely, external hexagon  154  of insert tool  101  is accommodated in internal profile  152 , or rather internal hexagon  153  of tool-receiver section  211  with the aid of a form-locking connection that by preference is free of rotational play, but at least is mostly free of rotational play. 
       FIG. 4  shows external profile  151 , or more specifically, external hexagon  154  of insert tool  101  upon sliding past magnet  310  of positioning device  300 , whereby insert tool  101  is rotated about its longitudinal central axis  189  in such a way that magnetic surface  312  abuts what may be full-surface on hexagon surface  158 , and thus a cross-section  160  of external profile  151  of insert tool  101  is aligned congruently with a cross-section  162  of internal profile  152  of tool receiver  200 . Consequently, insert tool  101  is able to be inserted virtually without resistance into internal receiver  210  with the aid of the transfer mechanism from  FIG. 1 , while at the same time creating a form-locking connection with internal receiver  210  of tool receiver  200  that is essentially free of rotational play. 
     Internal hexagon  153  is formed axially, at least sectionally, in sleeve-like tool-receiver section  211  of internal receiver  210  of tool receiver  200 . Centering section  156 —expanding in funnel-shaped or conical manner opposite to the insertion direction of insert tool  101  indicated by an arrow—in tool receiver  200  is used to further optimize the transfer process. 
       FIG. 5  shows tool receiver  200  from  FIG. 4  with a push bar  109  as a part of a transfer mechanism (compare especially  FIG. 1 ). This push bar  109  may be magnetized in area  335  of its free end  124 , that is to say, has a magnet  330  or a magnetized area at its free end  124 , whereby an axial connection is provided between insert tool  101  and push bar  109  that is sufficiently strong mechanically, but is easily releasable again if necessary. Consequently, in addition to implementing a change of insert tool  101 , insert tool  101  is able to be pulled without difficulty out of internal receiver  210  again with the aid of push bar  109 . 
     Magnet  330  or magnetized area  335  may be formed centrically in relation to longitudinal central axis  189  of insert tool  101  within free end  124  of push bar  109 . In this case, magnet  330  may be formed as a separate component and secured in suitable manner in free end  124  of push bar  109 , e.g., by press-fitting, thermal shrinkage, gluing in place, caulking, etc. If push bar  109  is formed with a ferromagnetic material, free end  124  may itself also be magnetized. 
     Illustratively, in  FIG. 5 , insert tool  101  is once again situated in the axial direction just before the state of complete insertion into tool receiver  200 , in which state, a form-locking connection, essentially free of rotational play, exists between external hexagon  154  of insert tool  101  and internal hexagon  153  of tool-receiver section  211  of internal receiver  210  of tool receiver  200 .