Abstract:
A system for a hand-held power tool has a tool housing, a receiving unit fixed to the tool housing and a guard unit connected with the hand-held power tool. The guard unit includes a guard extending at least partially around a rotatable tool. A guard anti-rotation lock device includes a clamping band fixedly connected to the guard that establishes a frictional connection between the guard unit and the receiving unit. The receiving unit includes a receiving flange and a connecting element that are together surrounded by and clamped in a clamping region by the clamping band to effect the frictional connection. In a case where the rotatable tool bursts into pieces during operation, the connecting element counteracts rotational movement of the guard unit with respect to the receiving unit by changing a cross-sectional shape of the clamping region.

Description:
CROSS-REFERENCE TO A RELATED APPLICATION 
     The invention described and claimed hereinbelow is also described in German Application DE 10 2006 053 305.4 filed on Nov. 13, 2006. This German Patent Application, whose subject matter is incorporated here by reference, provide the basis for a claim of priority of invention under 35 USC 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention is directed to a guard anti-rotation lock device. 
     An angle grinder with an adjustable guard is made known in EP 812 657 A1. In that case, the guard is adjustable in a rotating manner on a connection piece of a flange of the angle grinder, and is supported such that it may be detachably attached using a single form-fit locking means. The spindle of the angle grinder passes through the center of the flange. A cutting disk or grinding disk are/is installed on the free end of the spindle in a clampable, rotationally drivable manner for cutting and machining work pieces, which are partially enclosed by the guard. The guard must be positioned in a rotationally adjustable manner on the hand-held power tool such that the region of the grinding disk that faces the user is enclosed by the guard. At the same time, a region of the grinding disk that points away from the user extends past the flange, radially relative to the region of engagement with the work piece. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a guard anti-rotation lock device for a hand-held power tool, in particular for an angle grinder, which is provided to prevent rotation between the hand-held power tool and a guard unit. 
     It is provided that the anti-rotation lock device includes a non-positive connection unit, which is provided to prevent rotation between the hand-held power tool and the guard unit if a tool should burst. The guard unit is preferably provided to protect an operator—during regular operation of the hand-held power tool—from a tool, in particular from a disk-shaped, rotatably drivable tool, and/or from machining residue that is slung in the direction of the operator, or from a tool, in particular from a disk-shaped, rotatably drivable tool, or from machining residue that is slung in the direction of the operator, where the drivable tool is attached to the hand-held power tool in a working position. A “non-positive connection unit” refers, in particular, to a unit that is provided to establish a non-positive connection—that acts in the circumferential direction—between the guard unit and the hand-held power tool, and which is designed—when in an anti-rotation lock position between the guard unit and the hand-held power tool—to absorb forces of an outwardly-slung tool piece that could occur if a tool should burst. To attain an anti-rotation lock of the guard unit on the hand-held power tool, the guard unit, which is attached to the hand-held power tool, may be moved into the anti-rotation lock position by absorbing forces of impulses or forces of outwardly-slung pieces of the burst tool. “Provided” is intended to mean, in particular, specially equipped and/or designed. Due to the inventive design of the guard anti-rotation lock device, it is possible to effectively protect an operator of the hand-held power tool from a tool that rotates during operation of the hand-held power tool, and, in particular, from pieces of the tool that are slung in the direction of the operator if the tool becomes damaged, e.g., if the tool should burst. 
     In addition, according to the present invention, the non-positive connection unit is provided to establish a non-positive connection between the hand-held power tool and the guard unit by changing at least one shape parameter of a component of the hand-held power tool and/or the guard unit. As a result, advantageously, an increased frictional force may be attained between the guard unit and the hand-held power tool, in particular along contact surfaces for attaching the guard unit to the hand-held power tool if the tool should burst, thereby generating an additional force for fixing the guard unit in position. This may be attained in a particularly advantageous manner when the non-positive connection unit includes at least one non-positive connection element, which is provided to change the shape parameter of the hand-held power tool and/or the guard unit. Preferably, the shape parameter includes a cross-sectional area of a receiving unit of the hand-held power tool, and/or a diameter of a clamping band of the guard unit, and/or further shape parameters that appear reasonable to one skilled in the technical art. A “cross-sectional area of a receiving unit” refers, in particular, to a surface to be enclosed in a circumferential direction by the clamping band in order to attain a non-positive connection between the hand-held power tool and the guard unit. 
     It is also provided that the non-positive connection element is movably supported on the hand-held power tool and/or the guard unit, thereby making it possible to change the shape parameter using a simple design, in particular if a tool should burst. 
     If, in addition, the non-positive connection element is movable—together with the guard unit—into an anti-rotation lock position if a tool should burst, it is advantageously possible to change the shape parameter by changing the position—in particular the anti-rotation lock position—of the non-positive connection element. In addition, the energy of a piece of a burst tool that is transferred to the guard may be advantageously used to change the position of the non-positive connection element. An “anti-rotation lock position” refers, in particular, to a position of the guard unit relative to the hand-held power tool in which the guard unit is oriented opposite to a rotation, in particular a direction of rotation of the tool on the hand-held power tool, in particular on a receiving flange. 
     In an advantageous refinement of the present invention, it is provided that the non-positive connection unit includes a guide element in which the non-positive connection element is movably supported, thereby making it possible to realize a particularly specific motion into an anti-rotation lock position, and to realize a low-wear motion of the non-positive connection element. 
     Particularly advantageously, the non-positive connection element may be moved—together with the guard unit—into an anti-rotation lock position when the non-positive connection element is provided to be coupled to the guard unit in an at least partially form-fit or non-positive manner. In this context, “couplable” refers, in particular, to a driving—due to an at least partial form-fit connection and/or non-positive connection—of the non-positive connection element when a guard unit that is attached to the hand-held power tool rotates from a working position and into the anti-rotation lock position. The guard unit is rotated from the working position and into the anti-rotation lock position due to a transfer of force or a transfer of an impulse from a piece of a tool that has burst to the guard unit. 
     Particularly advantageously, the non-positive connection element is designed as a rolling element, and/or an eccentric element, and/or a wedge element, and/or a non-positive element designed as a ramp in a circumferential direction, and/or any other non-positive connection elements that appear reasonable to one skilled in the technical art. As a result, it is advantageously possible to obtain a rotational driving with the guard unit and/or a change to a shape parameter using a simple design. The term “circumferential direction” is intended to mean, in particular, a direction that is oriented essentially parallel to a direction of rotation of the tool during operation of the hand-held power tool or when the guard unit is in an installed state on the hand-held power tool. 
     When the wedge element also includes a thread that enables attachment to a receiving unit of the hand-held power tool, it is possible to attain—using a simple design—a change in shape of the receiving unit, in particular a receiving flange of the receiving unit, against which the guard unit bears in a state in which it is attached to the hand-held power tool, by widening the receiving unit to attain an anti-rotation lock position via a non-positive connection, if a tool should burst. 
     In an alternative embodiment of the present invention, a hand-held power tool system with a hand-held power tool, in particular an angle grinder, a guard unit, and a guard anti-rotation lock device are provided, in which case the guard anti-rotation lock device includes a non-positive connection unit, which is provided to prevent rotation between the hand-held power tool and the guard unit if a tool should burst. As a result, it is possible to effectively protect an operator of the hand-held power tool from a tool that rotates during operation of the hand-held power tool, and/or, in particular, from pieces of the tool that are slung in the direction of the operator if the tool becomes damaged, e.g., the tool should burst. To realize an anti-rotation lock of the guard unit on the hand-held power tool, the guard unit, which is attached to the hand-held power tool, may be moved into the anti-rotation lock position by absorbing impulses or forces of outwardly-slung pieces of the burst tool. 
     It is also provided that the non-positive connection unit includes at least one non-positive connection element, which is provided to change a shape parameter of the hand-held power tool and/or the guard unit. As a result, advantageously, an increased frictional force may be attained—via the non-positive connection element—between the guard unit and the hand-held power tool, in particular along contact surfaces for attaching the guard unit to the hand-held power tool, if the tool should burst, thereby generating an additional force for fixing the guard unit in position. Preferably, the shape parameter includes a cross-sectional area of a receiving unit of the hand-held power tool, and/or a diameter of a clamping band of the guard unit, and/or further shape parameters that appear reasonable to one skilled in the technical art. 
     When the hand-held power tool also includes a receiving unit in which the non-positive connection element is at least partially supported, it is possible to realize a particularly compact design of the non-positive connecting unit, at least to a certain extent, and/or if the non-positive connection element should become deformed due to a non-positive connection between the guard unit and the hand-held power tool if a tool should burst, then it is particularly easy to replace the non-positive connection element. 
     It is also provided that the receiving unit is designed slotted at least partially along a circumferential direction, thereby making it possible in a particularly advantageous manner to attain a reversible change in shape of the receiving unit, in particular a change of a cross-sectional area of the receiving unit. Slot-type openings in the receiving unit are preferably located on the receiving unit perpendicularly to the circumferential direction. 
     It is also provided that the receiving unit includes an intermediate ring on which the non-positive connection element is at least partially located, thereby making it possible to replace the non-positive connection element—using a simple design—if deformation should occur after a non-positive connection between the guard unit and the hand-held power tool if a tool should burst. 
     A simple design of the non-positive connection element for changing a shape parameter, in particular for reducing a diameter of a clamping band of the guard unit if a tool should burst, may be realized when the guard unit includes at least one closing unit, on which the non-positive connection element is at least partially located. The closing unit is preferably designed as a clamping closing unit and is provided to attach the guard unit to the hand-held power tool, the attachment advantageously taking place via a frictional connection between the clamping band and the hand-held power tool. Particularly advantageously, the non-positive connection element is located in the region of a closing element, e.g., in the region of a clamping screw, a clamping lever, and/or further closing elements that appear reasonable to one skilled in the technical art. 
     Particularly advantageously, the present invention includes a hand-held power tool for a rotating, preferably disk-shaped tool, with a machine housing that includes a flange or a machine neck, on which a guard—that is composed of sheet metal in particular—is detachably clampable in order to cover the tool. The guard includes a guard body, which is composed of a circular, disk-shaped piece, in particular with an outer edge located at a right angle thereto, and with a central, circular recess, on the edge of which a guard connection piece or collar is formed and that includes an annular clamping band that may be tightened using a clamping means. An anti-rotation lock that acts between the machine neck and the guard is located between the guard and the machine neck and is designed as a profiled structure. The guard may be repeatedly coupled via the clamping band and/or the clamping means in its clamping position in a form-fit and/or non-positive manner with the machine neck, and is therefore capable of being fixed in a non-rotatable position and, to attain a release position, may be disengaged from the form-fit and/or non-positive connection, so that the guard may then be adjusted in a rotational manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantages result from the description of the drawing, below. Exemplary embodiments of the present invention are shown in the drawing. The drawing, the description, and the claims contain numerous features in combination. One skilled in the art will also advantageously consider the features individually and combine them to form further reasonable combinations. 
         FIG. 1  shows an exploded view of an inventive hand-held power tool system, 
         FIG. 2  shows a guard anti-rotation lock device with a non-positive connection element designed as an eccentric element, in a schematic, partial cross-sectional view, 
         FIG. 3  shows a guard anti-rotation lock device with a non-positive connection element that is movably supported inside a guide element, in a schematic, partial cross-sectional view, 
         FIG. 4  shows a guard anti-rotation lock device with a non-positive connection element designed as an eccentric element in the region of a closing unit of a guard unit, in a schematic, partial cross-sectional view, 
         FIG. 4A  shows a perspective view of the guard anti-rotation lock device depicted in  FIG. 4 ; 
         FIG. 5  shows a guard anti-rotation lock device with a non-positive connection element designed as a wedge element, in a schematic, partial cross-sectional view, 
         FIGS. 6   a ,  6   b  show a guard anti-rotation lock device with a wedge element having an alternative design to that shown in  FIG. 5 , in a schematic view from the top ( FIG. 6   a ), and in a cross-sectional view ( FIG. 6   b ), and 
         FIGS. 7   a ,  7   b  show a guard anti-rotation lock device with a non-positive connection element designed as an intermediate ring, which is coupled to a guard unit in a non-positive manner ( FIG. 7   a ) and in a form-fit manner ( FIG. 7   b ), in a schematic, partial cross-sectional view. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  shows a hand-held power tool system  40   a  with a hand-held power tool  12   a  designed as an angle grinder and shown only partially here, and with a guard unit  14   a  and a guard anti-rotation lock device  10   a . Hand-held power tool  12   a  includes a hand-held power tool housing  46   a , and a receiving unit  24   a  for receiving guard unit  14  or a tool  18   a  designed as a cutting disk, receiving unit  24   a  being screwed together with hand-held power tool housing  46   a . A drive shaft  50   a  extends out of receiving unit  24   a  on a side  48   a  facing away from hand-held power tool housing  46   a . Drive shaft  50   a  is connectable at its free end  52   a  with disk-shaped tool  18   a  and is rotationally drivable around an axis  54   a . Guard unit  14   a  includes a guard  56   a  and a closing unit  44   a . When hand-held power tool system  40   a  is in an installed state, guard  56   a  extends around an angular range of tool  18   a  of approximately 180.degree. and, to this end, includes a semi-disk shaped guard body  58   a  and a guard edge  60   a , which is initially oriented perpendicularly to semi-disk shaped body  58   a  and is finally oriented parallel to semi-disk shaped guard body  58   a , inwardly in a radial direction  62   a.    
     Guard unit  56   a  also includes a guard collar  64   a , which is oriented essentially perpendicularly to semi-disk shaped guard body  58   a . Guard collar  64   a  is enclosed outwardly in radial direction  62   a  by a clamping band  28   a  of closing unit  44   a . Guard collar  64   a  and clamping band  28   a  are interconnected via a welded connection. Guard collar  64   a —together with clamping band  28   a —is provided to attach guard unit  14   a  to hand-held power tool  12   a  or to receiving unit  24   a , which includes a cylindrical receiving flange  66   a  for this purpose. Along a circumferential direction  38   a ,  68   a  of clamping band  28   a , clamping band  28   a  includes two end regions  70   a ,  72   a  in a region that faces away from guard  56   a  and extends outwardly in radial direction  62   a . End regions  70   a ,  72   a  each include a recess  74   a , through which a closing element  76   a —designed as a clamping screw—of closing unit  44   a  extends (see  FIG. 2 ). The clamping screw may be fastened in recesses  74   a  of the clamping band using a nut. Guard  56   a  is attached in a working position to receiving unit  24   a  or on receiving flange  66   a  via closing unit  44   a  using a frictional connection between guard collar  64   a  and clamping band  28   a  and receiving flange  66   a , so that guard unit  14   a  is positioned in a non-rotatable manner during regular operation of hand-held power tool  12   a . In an alternative design of closing unit  44   a , it is basically feasible to use—instead of the clamping screw—further closing elements, e.g., a clamping lever or form-fit elements, etc. 
     Hand-held power tool system  40   a  also includes a coding device  78   a , which is provided to prevent tools  18   a  or tools  18   a  together with guard unit  14   a  from being installed on unsuitable hand-held power tools  12   a . To this end, clamping band  28   a  includes a coding element  80   a  of coding device  78   a , which is designed as a single piece with clamping band  28   a . Coding element  80   a  is designed as a pressed-out region that extends inwardly in radial direction  62   a  and has a rectangular shape. Correspondingly, receiving flange  66   a  includes a coding element  82   a  of coding device  78   a , which is designed as a recess into which coding element  80   a  of clamping band  28   a  may be inserted when guard unit  14   a  is installed on hand-held power tool  12   a . After guard unit  14   a  has been inserted onto receiving unit  24   a , guard unit  14   a  may be rotated into a working position. To this end, receiving flange  66   a  includes a groove  84   a  that extends in circumferential direction  38   a ,  68   a , in which coding element  80   a  is guided when guard unit  14   a  is rotated into the working position. 
       FIG. 2  shows guard anti-rotation lock device  10   a  in  FIG. 1  in greater detail. Guard anti-rotation lock device  10   a  is provided to prevent rotation between guard unit  14   a  and hand-held power tool  12   a  or receiving unit  24   a  during a breakdown of tool  18   a , e.g., when a tool  18   a  bursts. To this end, guard anti-rotation lock device  10   a  includes a non-positive connection unit  16   a , which is provided to prevent rotation—via a non-positive connection—between hand-held power tool  12   a  and guard unit  14   a  if a tool  18   a  should burst. A non-positive connection is established between hand-held power tool  12   a  and guard unit  14   a  by changing a shape parameter of a component of hand-held power tool  12   a  designed as a receiving flange  66   a . The shape parameter is designed as a cross-sectional area of receiving unit  24   a  or receiving flange  66   a  to be enclosed by clamping band  28   a  in circumferential direction  38   a ,  68   a . Cross-sectional area extends essentially perpendicularly to axis  54   a  of drive shaft  50   a . To this end, receiving unit  24   a  includes a non-positive connection element  20   a  of non-positive connection unit  16   a , which is provided to change cross-sectional area of receiving flange  66   a.    
     To change cross-sectional area, non-positive connection element  20   a  is designed as a cylindrical rolling element  32   a , and it is movably supported in receiving flange  66   a  in an edge region  86   a  of receiving flange  66   a  located outwardly in radial direction  62   a . Non-positive connection element  20   a  couples in a non-positive manner to clamping band  28   a  or guard collar  64   a  of guard unit  14   a . A side  88   a  of rolling element  32   a  that points outwardly in radial direction  62   a  when guard unit  14   a  is in an installed working position on hand-held power tool  12   a  hears against a surface  90   a —that faces inwardly in radial direction  62   a —of clamping band  28   a  or of guard collar  64   a  of guard unit  14   a . In addition, non-positive connection element  20   a  is designed as an eccentric element  34   a , and it is supported in receiving flange  66   a  such that it may rotate around a rotation axis  92   a , which is oriented essentially parallel to axis  54   a  of drive shaft  50   a . During regular operation of hand-held power tool system  40   a , a subregion  94   a  of eccentric element  34   a  bears against clamping band  28   a  or guard collar  64   a  that is located the shortest distance  96   a  away from rotational axis  92   a.    
     If a tool  18   a  should burst during operation of hand-held power tool  12   a , tool pieces are slung outwardly in a rotation direction  98   a  of tool  18   a . If one of these tool pieces strikes guard unit  14   a , the kinetic energy of the tool piece transferred to guard unit  14   a  exceeds the attachment energy of the frictional connection of closing unit  44   a  between guard unit  14   a  and hand-held power tool  12   a . Guard unit  14   a  is then rotated out of its working position and in rotation direction  98   a  of tool  18   a . Eccentric element  34   a , which couples on surface  90   a —which faces inward in radial direction  62   a —of clamping band  28   a  or guard collar  64   a  in a non-positive manner, is rotated around rotation axis  92   a  in direction  100   a , which is oriented in rotation direction  98   a  of tool  18   a . Due to a motion of guard unit  14   a , eccentric element  34   a  walks around clamping band  28   a  or guard collar  64 , so that eccentric element  34   a  is moved together with guard unit  14   a . In addition, it is also feasible for surface  90   a —which faces inwardly in radial direction  62   a —of clamping band  28   a  or guard collar  64   a , or an outer surface of eccentric element  34   a  to have a high friction coefficient in order to increase a non-positive connection between eccentric element  34   a  and clamping band  28   a  or guard collar  64   a  due to a special material selection or a special surface treatment. 
     Due to the rotation of eccentric element  34   a , a subregion  102   a  of eccentric element  34   a  that is located a greater distance  96   a  away from rotation axis  92   a  than is subregion  94   a  with shortest distance  96   a , is rotated outwardly. As a result, cross-sectional area of receiving flange  66   a  increases and a frictional force between receiving flange  66   a  and clamping band  28   a —together with guard collar  64   a —is increased. Kinetic energy transferred from the tool piece to guard unit  14   a  is partially absorbed by the acting frictional force, and, as soon as the frictional force reaches equilibrium with a residual impulse of guard unit  14   a  along rotation direction  98   a , guard unit  14   a  is held in an anti-rotation lock position. 
     In a further embodiment of the present invention, it is feasible to increase the number of eccentric elements  34   a  or to change a location of eccentric element  34   a  within receiving flange  66   a  in a manner that appears reasonable to one skilled in the technical art. 
     Alternative exemplary embodiments are shown in  FIGS. 3 through 7   b . Components, features, and functions that are essentially the same are labelled with the same reference numerals. To distinguish the exemplary embodiments from each other, the reference numerals of the exemplary embodiments are appended with the letters a through f. The description below is essentially limited to the differences from the exemplary embodiment in  FIGS. 1 and 2 . With regard for the components, features, and functions that remain the same, reference is made to the description of the exemplary embodiment in  FIGS. 1 and 2 . 
       FIG. 3  shows a schematic, partial cross-sectional view of an alternative guard anti-rotation lock device  10   b  of a hand-held power tool system. Guard anti-rotation lock device  10   b  includes a non-positive connection unit  16   b  with a non-positive connection element  20   b , which is designed as a cylindrical rolling element  32   b , and which is provided to prevent rotation between a not-shown hand-held power tool and a guard unit if a tool should burst. Non-positive connection unit  16   b  also includes a guide element  30   b , in which rolling element  32   b  is movably supported. Guide element  30   b  is located in a receiving flange  66   b  in an edge region  86   b —which is located outwardly in radial direction  62   b —of receiving flange  66   b , and it is tapered in design in a rotation direction  98   b  of a tool. Rolling element  32   b  is secured—in an expanded region  104   b  of guide element  30   b  via a not-shown release-prevention mechanism—against being moved in rotation direction  98   b  while the guard unit is changing position or when guard unit is removed. If a frictional force between rolling element  32   b  and a clamping band  28   b  or a guard collar exceeds a retaining force of the release-prevention mechanism, as occurs when the guard unit rotates in rotation direction  98   b  due to a transfer of kinetic energy of an outwardly slung piece of a burst tool, rolling element  32   b  is moved into an anti-rotation lock position along with the guard unit. An anti-rotation lock using non-positive connection element  20   b  is similar to that described with reference to  FIG. 2 . 
       FIG. 4  shows a schematic, partial cross-sectional view of an alternative guard anti-rotation lock device  10   c  of a hand-held power tool system. Guard anti-rotation lock device  10   c  includes a non-positive connection unit  16   c  with a non-positive connection element  20   c , which is designed as an eccentric element  34   c , and which is provided to prevent rotation between a hand-held power tool and a guard unit if a tool should burst. Non-positive connection element  20   c  is provided to change a shape parameter—represented by a diameter  26   c —of a component of the guard unit that is designed as clamping band  28   c . Non-positive connection element  20   c  is also located on a closing unit  44   c  of the guard unit and, to this end, is designed as a single piece with a clamping closing element  106   c . Eccentric element  34   c  also includes a hook element  108   c , which, when the guard unit is in a working position, engages in one of several recesses  110   c  provided in a receiving flange  66   c  of the hand-held power tool in order to receive hook element  108   c . When the guard unit is moved, together with eccentric element  34   c , in a rotation direction  98   c  of the tool due to a piece of a burst tool striking the guard unit, hook element  108   c  is pressed against a wall  112   c  of recess  110   c , eccentric element  34   c  is rotated around rotation axis  92   c , and a subregion  114   c  of eccentric element  34   c  with a greatest distance  96   c  relative to rotation axis  92   c  is rotated in the direction of receiving flange  66   c . This brings about a reduction in diameter  26   c  of clamping band  28   c , which, in turn, results in hook element  108   c  being fixed more securely in position in recess  110   c . An anti-rotation lock of the guard unit results from the non-positive connection, in a manner similar to that described with reference to  FIG. 2 . 
       FIG. 4A  is presented to provide a perspective view of the guard anti-rotation lock device  10   c  designed to include an eccentric element  34   c  in the region of a closing unit  44   c  of a guard unit, as depicted in  FIG. 4   
       FIG. 5  shows an alternative guard anti-rotation lock device  10   b  of a hand-held power tool system, in a schematic, partial cross-sectional view. Guard anti-rotation lock device  10   d  includes a non-positive connection unit  16   d  with a non-positive connection element  20   d , which is designed as a wedge element  36   d , and which is provided to prevent rotation between a hand-held power tool and a guard unit if a tool should burst. Wedge element  36   d  is designed such that it tapers conically along a direction  116   d , which extends essentially perpendicularly to a cross-sectional area of a receiving flange  66   d , on a region  118   d  that faces receiving flange  66   d . In this region  118   d , wedge element  36   d  includes—on a surface  120   d  that faces outwardly in radial direction  62   d —a not-shown thread, via which wedge element  36   d  is located in a manner such that it may be screwed and unscrewed with a not-shown counter-thread on a surface  122   d , which is located inwardly in radial direction  62   d —of receiving flange  66   d . To this end, receiving flange  66   d  includes a conically tapered recess  126   d  in a region  124   d  that faces inwardly in radial direction  62   d . Wedge element  36   d  is designed cylindrical in shape in a region  128   d  facing away from receiving flange  66   d . A diameter of wedge element  36   d  is essentially equal to an outer diameter of receiving flange  66   d . In cylindrical region  128   d  of wedge element  36   d , when the guard unit is in an installed working position, a clamping band  28   d  bears against a surface  130   d  that is oriented outwardly in radial direction  62   d . A frictional force between surface  130   d  of wedge element  36   d  and clamping band  28   d  is greater than a frictional force between receiving flange  66   d  and clamping band  28   d . If a tool should burst, or if the guard unit rotates in the direction of rotation of the tool, wedge element  36   d  is also rotated, due to a non-positive connection with clamping band  28   d , and it is rotated into receiving flange  66   d . A conically tapered design of wedge element  36   d  results in a widening of a cross-sectional area of receiving flange  66   d , which is designed slotted in the circumferential direction for this purpose, thereby preventing an irreversible deformation of receiving flange  66   d . An anti-rotation lock of the guard unit results from the non-positive connection, in a manner similar to that described with reference to  FIG. 2 . 
     An alternative design of guard anti-rotation lock device  10   e  of a hand-held power tool system is shown in  FIGS. 6   a  and  6   b . Guard anti-rotation lock device  10   e  includes a non-positive connection unit  16   e  with a non-positive connection element  20   e , which couples to a guard unit in a form-fit manner. To this end, non-positive connection element  20   e  designed as wedge element  36   e  includes—in an outer edge region  132   e  in radial direction  62   e —a recess  134   e  that extends in circumferential direction  38   e ,  68   e , in which a form-fit element  136   e  of the guard unit engages. Form-fit element  136   e  is located on a closing unit  44   e  of the guard unit, and it is designed as a tab-type hook element. Form-fit element  136   e  is brought into a form-fit position when the guard unit is attached or when closing unit  44   e  is closed in a non-positive manner using a clamping screw. An anti-rotation lock of the guard unit results from the non-positive connection, in a manner similar to that described with reference to  FIG. 5 . 
       FIGS. 7   a  and  7   b  show a schematic, partial cross-sectional view of an alternative guard anti-rotation lock unit  10   f  of a hand-held power tool system. Guard anti-rotation lock device  10   f  includes a non-positive connection unit  16   f  with a non-positive connection element  20   f , which is designed as an intermediate ring  42   f , and which is provided to prevent rotation between a hand-held power tool and a guard unit if a tool should burst. Intermediate ring  42   f  is captively located on a receiving flange  66   f  of a receiving unit  24   f . Intermediate ring  42   f  is designed in the shape of a ramp in a circumferential direction  38   f ,  68   f  on a surface  138   f  that is oriented inwardly in radial direction  62   f  and faces receiving flange  66   f . To this end, intermediate ring  42   f  includes ramp elements  140   f  located one after the other in circumferential direction  38   f ,  68   f , which engage in ramp elements  142   f —that have the same shape but face in opposite directions—on a surface  144   f —that is oriented outwardly in radial direction  62   f —of receiving flange  66   f . When the guard unit is installed in a working position, a surface  146   f —that is oriented outwardly in radial direction  62   f —of intermediate ring  42   f  couples in a non-positive manner with a clamping band  28   f  or a guard collar of the guard unit ( FIG. 7   a ). If a tool should burst, or if the guard unit rotates in rotation direction  98   f  of the tool, intermediate ring  42   f  is also rotated, due to a frictional force between clamping band  28   f  and intermediate ring  42   f , and ramp elements  140   f ,  142   f  of intermediate ring  42   f  and receiving flange  66   f  are displaced toward each other. A diameter of intermediate ring  42   f  is thereby widened, or a cross-sectional area of receiving unit  66   f  enlarges, together with intermediate ring  42   f , thereby resulting in an effective anti-rotation lock between the guard unit and receiving unit  24   f  due to a non-positive connection similar to that described with reference to  FIG. 2 . 
     In  FIG. 7   b , intermediate ring  42   f  couples in a form-fit manner with clamping band  28   f  for driving in a rotary manner if the guard unit should rotate due to a tool bursting. To this end, a closing element  148   f  designed as a clamping lever includes a cam  150   f , which, in a closed state, extends inwardly on the clamping lever in radial direction  62   f  away from a closing unit  44   f  designed as a toggle joint system. For driving in a form-fit, rotary manner, clamping band  28   f  and intermediate ring  42   f  each include a recess  152   f ,  154   f , through or in which cam  150   f  engages when the toggle joint system is in the closed state. An anti-rotation lock using intermediate ring  42   f  and a further embodiment of intermediate ring  42   f  is referenced in the description of  FIG. 7   a.