FIELD OF THE INVENTION 
     The invention relates to a fixing apparatus for releasably fixing, at least one functional component, in particular in the form of a tool holder, on another functional component, in particular in the form of a tool disk, about at least one fixing axis. The two functional components each have a bearing surface for mutual contact with one another. Both functional components have at least one fixing element. 
     BACKGROUND OF THE INVENTION 
     Tool disks are used in industrial manufacturing in combination with tool turrets. If several tool holders with associated tools (e.g., stationary cutting chisels or driven milling tools) are placed over the circumference of the tool disk, turning this arrangement allows for quick changing of the tools that is required for certain machining operations. Since only minimal manufacturing tolerances are generally allowed for machining workpieces, using such tool turrets in a meaningful way requires that the respective tool holder and the respective tool be fixed in a repeatable and exactly defined position relative to the tool disk. 
     EP 0 780 179 B1 discloses a fixing apparatus of the aforementioned type. This device as a fixing element incorporates a projecting molded body on the tool holder and provides a recess as a fixing element at the respective tool station of the tool disk. The recess receives the molded body of the tool holder when the bearing surface of the tool holder contacts the bearing surface of the tool disk. The molded body and the recess free of play then engage one another to position the tool holder on the tool disk. To obtain the required predetermined position for operating the tool holder, the fixing elements are adjustable relative to the tool holder and tool disk. With the prior art device, in this regard one proceeds by aligning the fixing element with the respective tool station of the tool disk by a master tool holder, fixing it in a position thus adjusted by screws. For the corresponding adjustment of the fixing element of the tool holder, a master tool station with a pre-adjusted fixing element is provided on the tool disk. At the tool holder attached on this master tool station, the fixing element of the tool holder is then also appropriately adjusted and likewise fixed by screws. Given the need to provide master components and performing adjustments, tool holders equipped with the prior art fixing apparatus become relatively complicated and costly in operation. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide an improved fixing apparatus characterized by being particularly easy to handle during operation and relatively inexpensive to construct. 
     This object is basically achieved according to the invention by a fixing apparatus having, as an important feature of the invention, two fixing bodies to form fixing elements on one of the functional components. The fixing bodies are spaced apart on both sides of the fixing axis and are in a fixed-position connection to the associated functional component. Each fixing body then forms a transverse fixing surface relative to the fixing axis, both of which from the same side may be placed against an associated positioning surface, which as fixing elements are located spaced apart on the other functional component. Due to the fixed-position connection of the fixing body forming the fixing surface with the associated functional component, no adjustments of the fixing elements are needed, thus simplifying handling. Compared with prior art fixing elements in the form of interlocking form locking elements, the invention is characterized by a simplified design, as the fixing suffices of both fixing bodies may be placed from the same side against the associated positioning surface of the other functional component, thus obviating the need for forming interlocking, free of play, form locking elements. 
     In an especially advantageous manner, the respective fixing surface may be formed on an integral fixing cam with the respective fixing body, with the fixing surface projecting from the bearing surface and defining a transverse fixing plane relative to the fixing axis. 
     Especially advantageously, the fixing elements of the other functional components, preferably the tool disk, have a recess in their bearing surface for forming the respective positioning surface for each fixing surface. The recess is bounded on one side by a wall portion forming the positioning surface. Thus, all components of the fixing apparatus are situated within the perimeter of the supporting surface, e.g., the tool disk, so that on the tool disk, no lateral, axially protruding parts of the fixing apparatus are found. 
     In especially advantageous embodiments, the fixing bodies are funned by a respective strip member mounted on opposite side faces of a rectangular base plate of the tool holder. 
     Especially advantageously, the strip members can be attached to the base plate by a threaded connection. The plate comprises form locking elements for forming a precision-fit connection without the use of an adjusting device. 
     The arrangement may here be implemented in a particularly advantageous manner such that each threaded connection for forming the precision-fit form locking between the screw and the associated holes in the strip member and base plate has a bushing seated snugly on the screw. The outer circumference of the bushing forms a fit with the holes of the strip member and the base plate. The threaded connection thus designed ensures fixation in an unchangeable position of the strip member as a result of the form locking formed at the external circumference of the bushing between the base plate and strip member and by precluding, any screw backlash due to the precision-fit of the bushing seated on the screw. 
     In a particularly advantageous manner, the strip members extend over a majority of the length of the relevant side face of the base plate, with a screw being provided at each end portion of the strip members. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring to the drawings that form a part of this disclosure: 
         FIG. 1  is a partial, exploded perspective view of a circumferential portion of the tool disk of a tool turret showing, a tool holder in a position raised away from the receiver of the tool disk according to an exemplary embodiment of the invention; 
         FIGS. 2 and 3  are partial top views of a tool station of the tool disk of  FIG. 1 , partially in section inside the tool disk of the splined shaft of a tool holder before and in the clamped state of the shaft, respectively; 
         FIG. 4  is a partial perspective view of the tool disk of  FIG. 1  in the area of the bearing surface of a tool station; and 
         FIG. 5  is an enlarged partial side view in section of the area of a threaded connection between the tool holder and a fixing body. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an exploded view of an exemplary embodiment of the fixing apparatus according, to the invention, for releasably fixing at least one functional component, presently in the form of a tool holder  1 , on a further functional component, here in the form of a tool disk  3 , about at least one alignment axis  5  extending in vertical alignment, as viewed in the line of sight in  FIG. 1 . On their adjacent facing sides, the tool holder  1  and the tool plate  3  have bearing surfaces  7  and  9 , respectively, that contact one another in the fixed state of the tool holder  1 . 
     Fixing elements  11  and  13  are present both on the bearing surface  9  of the tool disk  3  and the bearing surface  7  of the tool holder  1 . The fixing elements, when brought into paired interaction with one another, ensure fixation of the tool holder  1  on the tool disk  3  in relative positioning with respect to alignment axis  5 . The fixing elements  11  of the tool disk  3  have in the hearing surface  9  two recesses  15  situated on the two opposite side edges of the tool disk  3  at equal distances from an edge of the respective bearing surface  9  adjacent to the next following bearing surface  9 . The recesses  15  have, as is best shown in  FIGS. 2, 3, and 4 , the shape of a groove bounded by parallel walls at the opening. The groove expands on the interior end in a curved manner. With the side wall situated on the left side in  FIGS. 2 to 4 , the recess  15  thereby forms a positioning surface  17  in a fixing plane extending transversally relative to the alignment axis  5 . 
     The fixing, elements  13  on the tool holder  1  have two fixing bodies  19  mounted on opposite side faces  21  ( FIG. 5 ) of the rectangular base plate  23  of the tool holder  1  forming the bearing surface  7 . As explained in more detail below, the fixing bodies  19  are mounted on the tool holder  1  in unchangeable positions, i.e., non-adjustably. The fixing bodies  19  are provided on those side faces  21  of the base plate  23  corresponding with the side edges of the tool disk  3 , in which the recesses  15  open out. In accordance with this positional relationship, fixing surfaces  25  provided for interaction with the positioning surfaces  17  of the tool, disk  3  are located on the fixing body  19 . The fixing surfaces are located on the fixing bodies  19  each in proximity to the end of the side face  21  of the base plate  23 . 
     The fixing surfaces  25  are formed by the straight side faces of the fixing cams  27  integrated on the fixing bodies  19  and protruding from the plane of the bearing surface  7 . As can be seen in  FIG. 1 , the fixing bodies  19  are in the shape of strip members, with each extending on the respective side face  21  of the base plate  23  substantially along their entire lengths. At both stepped end portions of the bodies  19 , a threaded connection  29  is provided for fixed-position attachment to the base plate  21  of the tool holder  1 . The particulars of this threaded connection are shown in more detail in  FIG. 5 . Moreover, the side faces may also be spherically designed. 
     As shown in  FIGS. 1 to 3 , the tool holder  1  has a pin  31  as a holding part in the center of the bearing surface  7 . Pin  31  contains an indented surface  33  on the side facing away from the observer in  FIG. 1 , i.e., on the side facing right in  FIGS. 2 and 3 . A corresponding clamping member  35  with its indentation  37  ( FIG. 2 ) may engage indented surface  33  when inserting the pin  31  into a receiving hole  39  of the tool disk  3  located centrally in the bearing surface  9 . As shown in  FIGS. 2 and 3 , the clamping member  35  may be clamped by a clamping screw  41  with the indentation  37  to tighten the tool holder  1  on the tool disk  3 .  FIG. 3  shows this clamping situation. The clamping member  35  is brought forward via a feed hole  43  formed in the side face of the tool disk  3  and accordingly screwed in place. The locking engagement achieving this clamping is common in the art and the subject of, e.g., DIN 69880. By tightening the clamping screw  41 , a starting, torque is applied via the pin  31  to the tool holder  1  in the direction of the tool disk  3 , so that a high contact pressure will make the two corresponding bearing surfaces  7 ,  9  bear against one another by involving the pairwise interacting fixing and positioning surfaces  17 ,  19  for positioning the tool holder  1  relative to the tool disk  3 . 
     As mentioned above, the fixing bodies  19  with the integrally formed fixing, surface  25  thereon are in fixed-position connection with the tool holder  1 . This connection is achieved, by the threaded connections  29  comprising form locking elements, shown in more detail in  FIG. 5 . A precision-fit connection, without screw backlash, is formed. For this purpose, both the hole  45  in the fixing body  19  and the hole  47  in the base plate  23  of the tool holder  1 , at their mutually facing ends, have steps  49  and  51 , respectively, widening the hole diameter. A fitting bushing  55  is arranged on the screw  53  and precision-fit seated on the fixing screw  53 . Fixing screw  53  penetrates the holes  45  and  47 , whereby the outer circumference of the fitting bushing is snugly seated in the expansions of the holes  45 ,  47  formed by the steps  49 ,  51 . 
     When tightening the screw  53 , a form locking connection between the fixing body  19  and the base plate  23 , i.e., a non-adjustable connection between the fixing surface  25  and the tool holder  1 , is created. When operating the fixing apparatus for the first time, one therefore proceeds by mounting the strip members  19 , initially with unmachined fixing surfaces  25 , on the tool holder  1 , and centering it by the precision-fit bushings  25 . After tightening the screws  53 , the fixing bodies  19  are no longer adjustable. In accordance with the requirements of the high-precision definition of the position of the positioning surfaces  17  on the tool disk  3 , the two fixing surfaces  25  of the fixing bodies  19  are then finished. After finishing with high precision, fixation in a predetermined position is achieved without the need of any adjustments. 
     A preferred embodiment of the solution according to the invention provides that the respective fixing body  19  be slotted comparable to the subsequently published DE 10 2009 033 805.5, and in accordance with the illustrations of  FIGS. 4, 4   a , and  4   b  of the subsequently published document. The pertinent longitudinal slot  57  divides the strip member  19  into two mutually connected segments  59 ,  61  at the bottom. The strip-shaped fixing body  19  is then implemented in a slotted manner, while forming two interconnected strip members  59 ,  61 , whereby one strip member  59  with the fixing surface  25  connected with the cams  27  is fairly movable relative to the other strip member  61  connected to the tool holder  1  in a slot-narrowing manner, so that the gap  57 , at its free upper end, narrows from the free gap cross-section or clearance. 
     The fixing body  19  is thus designed similar to a cuboid-shaped structural member penetrated by a groove from the upper side, forming an engagement slot  57 , with the slot opening downward into a bridge as a connecting link between the two strip members  59  and  61 . In this way, a bending joint is implemented on the bridge, whereby the strip member  59  can be supplied to the strip member  61  during elastic deflection around this bending point. This swiveling movement of the strip member  59  occurs only if the tool holder  1  in its corresponding installed state is located on the disk  3 . In this way, the respective fixing surface  25  comes into contact with the associated positioning surface  17 , possibly only partially, on the tool disk  3 . 
     While one embodiment has been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.
A fixing apparatus releasably fixes functional elements, particularly a tool holder ( 1) on a tool disk ( 3), about one fixing axis ( 5). These two functional components each have a bearing surface ( 7, 9) for bearing mutually against one another, and at least one fixing element ( 11, 13). The fixing element ( 13) has two fixing bodies ( 19) connected in a positionally unchangeable manner to the associated functional component on both sides of the fixing axis ( 5) and at a spacing from one another. Each fixing body ( 19) forms a fixing surface ( 25) extending transversely with respect to the fixing axis ( 5). The fixing surfaces ( 25) can both be placed from the same side against an associated positioning surface ( 17) and are situated as fixing elements ( 11) on the other functional component at a spacing from one another.