Abstract:
A drill head including a tool holder, chisel supports mounted thereon and drill bits. According to this invention, the chisel supports can be separated from the tool holder.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to a tool holder for a drill head with a fastening shank through which a mud channel passes and with a support structure fastened directly or indirectly to the fastening shank. 
         [0003]    This invention also relates to a drill bit support for a drill head, with a support head on which a bearing section of a drill bit that can be fastened in rotary fashion. 
         [0004]    This invention also relates to a drill bit for rotary attachment to a drill bit support. 
         [0005]    2. Discussion of Related Art 
         [0006]    Drill heads are used to dig drilling holes in the ground for construction projects. To do so, the drill heads are fastened at one end to a drill pipe. The rotation and the advancing motion of a drive unit are transferred to the drill head by the drill pipe. 
         [0007]    For example, horizontal drilling machines are known, which are used to produce a relatively horizontal bore in the ground. This is done to drive the drill head under roads, buildings, or the like. Usually, the drill heads have a tool holder that holds drill bits, which are supported in sockets in rotary fashion. When the drill head is driven through the ground, the drill bits roll against the material to be removed and break it free. This causes it to fragment so that it can be flushed away with a mud emulsion. The mud emulsion is supplied to the drill heads via the drill pipe. The drill heads are subject to wear and thus must be regularly replaced. 
       SUMMARY OF THE INVENTION 
       [0008]    One object of this invention is to provide a drill bit support and a drill bit, which are designed so that they are optimized with regard to wear. 
         [0009]    This object and others of this invention relating to the tool holder are attained if the support structure has tool sockets offset from one another in the circumference direction for accommodating drill bit supports in a replaceable fashion. 
         [0010]    According to this invention, there is a wear system in which the tool holder has an interface for the replaceable coupling of the drill bit support. Consequently, the tool holders and the drill bit supports can be replaced independently of one another in accordance with their wear state. This achieves an optimization of the service life of the individual tool components. 
         [0011]    According to one embodiment of this invention, it is possible for the tool sockets to be embodied or shaped in the form of insertion sockets. Thus, the drill bit supports can be easily changed and precisely positioned, even in the rough conditions of worksite operations and in installation situations with limited accessibility. 
         [0012]    In this connection, it is particularly advantageous if the tool sockets have an insertion opening, which opens in the direction oriented away from the fastening shank or in a radially outward direction. Thus, the drill bit supports can be inserted into the insertion sockets from the front side or the rear side of the drill head. Alternatively, the insertion socket can also be embodied or shaped in the form of a guide projection onto which the drill bit support can be slid. 
         [0013]    A tool holder according to this invention can be embodied or formed so that in the region of the tool socket, a fastening receptacle, in particular a screw receptacle, is provided, which opens in the direction toward the fastening shank and is accessible from there. Thus, the screw receptacle is oriented so that the screw head of a fastening screw is inserted into the screw receptacle and is favorably positioned with regard to wear. In particular, it is then not exposed to the abrasive wear action. 
         [0014]    A possibility for exact positioning of the drill bit supports is provided in a simple way if the tool sockets have two guide grooves or guides situated on opposite sides from each other. 
         [0015]    Thus, a favorable centering is achieved if the guide grooves are laterally delimited by two flanks, which extend in the longitudinal direction of the groove and are oriented at an angle relative to each other. This design is also load-optimized. The wall sections of the tool sockets that form the grooves become thicker in the direction toward the bottom of the groove and thus have a large load cross-section at the location in which the highest loads occur. 
         [0016]    Preferably, the tool sockets each at least partially comprises two guide projections and outlet channels formed between the guide projections of adjacent tool sockets. The rock material that is removed with the supplied emulsion can be conveyed away via the outlet channels. 
         [0017]    One object of this invention relating to the drill bit support is achieved if an insertion lug is directly or indirectly coupled to the support head of the drill bit support. With this insertion lug, the drill bit support can be inserted into a correspondingly embodied tool socket of the tool holder. It can then be replaced independently of the tool holder, each as a function of its individual wear state. This achieves a wear-optimized design. With its insertion lug, the drill bit support can be quickly and simply attached to the tool holder and detached from it again. 
         [0018]    The insertion lug can have guide pieces on two opposing sides. With these guide pieces, it can be inserted, for example, into grooves of the tool holder, in order to thus achieve a reliable and exact positioning. 
         [0019]    For a load-optimized design, the guide pieces can have two guide surfaces that are oriented at an angle relative to each other and are connected to each other via a connecting section. The guide pieces widen out starting from their free ends and thus have their maximum cross-section in the region in which they connect to the drill bit support and therefore have a load-optimized design. 
         [0020]    In one embodiment of this invention, the insertion lug has a support lug at its free end and this support lug produces an additional stable attachment. 
         [0021]    For example, it is also possible for the support lug to transition into the guide pieces in a way that results in an easy-to-produce geometry. 
         [0022]    A drill bit support according to this invention can also be embodied so that the insertion lug is delimited by a convex inner surface and/or a convex outer surface. In the region of the convex inner surface, the drill bit support can correlate with a correspondingly concave recess of the tool holder. The matching convex/concave regions in the vicinity of the inner surface produce an interface, which, like a key in a lock, promotes the association of the correct drill bit support with a tool holder. The convex outer surface of the drill bit support reduces the number of possible weak points of the bore wall and thus contributes to a wear-optimized layout of the tool design. The convex shape also achieves a thickening of the insertion lug cross-section and thus a greater stability. 
         [0023]    A drill bit support according to this invention can have a support head that supports a bearing section and labyrinth seal parts are positioned or situated in the transition region from the support head to the bearing section. These labyrinth seal parts can be put together with corresponding labyrinth seal parts of a drill bit in order to thus produce a labyrinth seal. This labyrinth seal counteracts the penetration of rock material and thus protects the bearing section and a bearing contained therein. 
         [0024]    A drill bit can be simply affixed to a drill bit support so that the bearing section has a circumferential groove for accommodating a clamping element. The clamping element can then be connected to the drill head with form-locking engagement and/or frictional, nonpositive engagement. 
         [0025]    In one embodiment according to this invention, the central longitudinal axis formed by the bearing section extends at an angle in the range between 30° and 90° in relation to the outer surface. This achieves an optimization of the bearing pressure on the bearing between the drill bit and the tool support. It is advantageous for this angular range to lie between 50° and 70°. This also produces an outer surface of the drilling tool that is functional and easy to shape. 
         [0026]    One object of this invention is also achieved with a drill bit for coupling to a drill bit support in rotary fashion. The drill bit has an outer surface with hard material elements. The drill bit also has a bearing receptacle. In the region of the bearing receptacle, the drill bit according to this invention has labyrinth seal parts, which can be put together with labyrinth seal parts of the drill bit support to form a labyrinth seal. This labyrinth seal counteracts the penetration of rock material, thus using simple means to effectively protect the bearing receptacle from wearing action. 
         [0027]    In order to also maintain a reliable position-fixing relative to the drill bit support, even when there are abrupt and uneven loads on the drill bit, it is possible according to this invention for the bearing receptacle to have an end surface that supports a support element of hard material. This support element can cooperate with a counterpart support element or a counterpart surface of the drill bit support. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    This invention is explained in greater detail below in view of an exemplary embodiment shown in the drawings, wherein: 
           [0029]      FIG. 1  is a perspective side view of a drill head with a tool holder and, mounted thereon, drill bit supports with drill bits; 
           [0030]      FIG. 2  is a partial section view taken through the drill head according to  FIG. 1 ; 
           [0031]      FIG. 3  is a perspective front view of a drill bit support; 
           [0032]      FIG. 4  is a perspective front view of a drill bit support with drill bits mounted thereon; 
           [0033]      FIG. 5  is a sectional detail view taken along line V-V in  FIG. 2 ; 
           [0034]      FIG. 6  is a perspective side view of another embodiment of a drill head with a tool holder and, mounted thereon, drill bit supports with drill bits; 
           [0035]      FIG. 7  is a partial section view taken through the drill head according to  FIG. 6 ; 
           [0036]      FIG. 8  is a perspective front view of a drill bit support; 
           [0037]      FIG. 9  is a sectional detail view taken along line IX-IX in  FIG. 7 ; 
           [0038]      FIG. 10  is a full section view taken through the drill bit support according to  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]      FIG. 1  shows a drill head with a tool holder  10  having a base part as a support structure  12 . The support structure  12  has a downward-pointing fastening shank  11  integrally formed onto it. The fastening shank  11  has a conical external thread. The support structure  12  has three tool sockets  13 , which protrude from the outside of the support structure  12  and are offset from one another by 120° and are embodied in the form of pockets. 
         [0040]      FIG. 5  shows one embodiment of the tool sockets  13  in greater detail. As shown, each tool socket  13  has two guide projections  13 . 1  on the outside. The guide projections  13 . 1  each is provided with or has a respective guide groove  13 . 2 , the guide grooves  13 . 2  of a tool socket  13  are situated on opposite sides from each other. The guide grooves  13 . 2  are delimited laterally by flanks  13 . 3  that are oriented at an angle with respect to each other, preferably in the range between 80° and 100°. This angular range ensures a reliable and jam-free function of the guide. The two guide projections  13 . 1  form convex surfaces on the outside, which lie along a pitch circle, as shown in  FIG. 5 . 
         [0041]      FIG. 1  shows that in the region of the fastening shank  11 , the guide projections  13 . 1  are connected by a transition section that is provided with or has a screw receptacle  12 . 1 , as shown in  FIG. 2 . The screw receptacle  12 . 1  serves to accommodate a fastening screw  12 . 2 . The screw receptacle  12 . 1  is let into the support structure  12  so that it feeds into the tool socket  13  and so that it is oriented toward the free end of the fastening shank  11 . In this way, the head of the fastening screw  12 . 2  is accommodated in a protected way, on the side oriented away from the advancing direction of the drill head. The support structure  12 , as shown in  FIG. 2 , has a mud channel  15  passing through it. The mud channel  15  feeds into a nozzle. The nozzle  15 . 1  transitions into a channel chamber  14 , which feeds into the outlet channels  14 . 1 . The outlet channels  14 . 1  are each situated between the guide projections  13 . 1  of adjacent tool sockets  13 . 
         [0042]    Drill bit supports  20  can be mounted in the tool sockets  13 . The design of the drill bit support  20  is shown in greater detail in  FIG. 3 . As shown, the drill bit support  20  has an insertion lug  21  that terminates with an inner surface  24  and on the outside, with a convex outer surface  25 . Rib-like guide pieces  22  are integrally formed onto the sides of the insertion lug  21 . The guide pieces  22  have two guide surfaces  22 . 1  oriented at an angle with respect to each other so that the guide pieces  22  taper from their connecting region to the insertion lug  21  toward their free end. The inclination angle is selected in accordance with the angle between the flanks  13 . 3 . The guide surfaces  22 . 1  transition into one another via a connecting section  22 . 2 . In the region of or near the free end of the insertion lug  21 , a support lug  23  is formed, which is embodied as a transition section and, like the guide pieces  22 , is embodied as rib-like. The support lug  23  transitions flush into the guide pieces  22  and thus has the same cross-sectional geometry. Consequently, it has guide surfaces  23 . 1  inclined in relation to each other and in turn connected to each other by a connecting section. 
         [0043]    The insertion lug  21  has a support head  26  with a bearing section  26 . 3  formed integrally onto it. In the transition region to the bearing section  26 . 3 , the support head  26  has an annular shoulder  26 . 1  extending around it, which is adjoined by a circumferential groove  26 . 2 . The shoulder  26 . 1  and the groove  26 . 2  constitute or form labyrinth seal parts. The cylindrical bearing section  26 . 1  is first adjoined by a concave transition  26 . 4  in order to adapt its size to a reduced-diameter connector piece at the end. A circumferential groove  26 . 5  is incorporated into the connector piece. The bearing section  26 . 3  terminates at its end with an end surface  26 . 7 . As shown in  FIG. 2 , the end surface  26 . 7  has a recess incorporated into it, into which a support element  26 . 6 , composed of or comprised of a hard material such as a hard metal, is soldered, glued, or press-fitted.  FIG. 2  also shows that an annular clamping element  29 . 1  in the form of a round wire snap ring is snapped into the circumferential groove  26 . 2 . 
         [0044]      FIGS. 2 and 4  show that a drill bit  30  can be connected to the drill bit support  20 . The drill bit  30  has an outer surface  31  with at least one circumferential groove  32 ,  33 . Hard material elements  34 , in particular hard metal elements, can be soldered into holes on the outer surface  31 . The drill bit  30  has an internal bearing receptacle  37  that is embodied or shaped in the form of a hole in the drill bit  30 . The bearing receptacle  37  transitions via a diameter reduction into a blind hole bore that is equipped with or has a groove  38 . The blind hole bore terminates with an end surface, in which a recess for a support element  39  is provided. The support element  39  can be composed of or comprised of a hard material such as hard metal. In the end region of the bearing receptacle  37 , the drill bit  30  is provided with or has a circumferential groove  35  and an adjoining circumferential shoulder  36 . The groove  35  and the shoulder  36  are labyrinth seal parts. To mount the drill bit  30  on the drill bit support  20 , a bearing  29  is inserted into the bearing receptacle  37  of the drill bit  30  and slid onto the bearing section  26 . 3  of the drill bit support  20 . The bearing  29  in this embodiment is formed as a needle bearing, making it possible to achieve a small overall height. 
         [0045]    As shown in  FIG. 2 , a radial shaft sealing ring or a similar circumferential seal  28  is also inserted in the region between the bearing receptacle  37  and the bearing section  26 . 3 . In the inserted state, the circumferential shoulder  36  of the drill bit  30  protrudes into the circumferential groove  26 . 2  of the drill bit support  20 . In a similar way, the circumferential shoulder  26 . 1  of the drill bit support  20  protrudes into the circumferential groove  35  of the drill bit  30 , so that a labyrinth seal is formed. Consequently, the circumferential shoulders  36  and  26 . 1  and the grooves  26 . 1  and  35  constitute formed-on seal profiles or labyrinth profiles. Adjacent to the labyrinth seal, the seal  28  seals the bearing receptacle  37  so that the labyrinth seal and the seal  28 , effectively protect the bearing  29  from the penetration of rock material and mud emulsion. This prevents premature failure of the bearing  29 . In order to affix the drill bit  30  to the drill bit support  20 , the clamping element  29 . 1  simultaneously engages in the grooves  26 . 5  and  38  of both the drill bit support  20  and the drill bit  30 . This produces a form-locked engagement between these components. In addition, the drill bit  30  is supported with its support element  39  on the support element  26 . 6  of the drill bit support  20 . During assembly of the drill bit  30 , the clamping element  29 . 1  slides between the bearing receptacle  37  and the region of the bore that accommodates the groove  38 . As a result, the clamping element  29 . 1  is compressed radially inward into the groove  26 . 2  and its diameter is reduced. The clamping element  29 . 1  can then snap into the groove  38  so that a form-locked connection is achieved. 
         [0046]    The tool combination composed of the drill bit support  20  and drill bit  30  can be inserted into a tool socket  13  of the tool holder  10 . For this purpose, the insertion lug  21  is slid into the tool socket  13 , which is embodied or shaped in the form of an insertion socket. In the process of this, the guide surfaces  22 . 1  of the guide pieces  22  slide along the flanks  13 . 3  of the guide grooves  13 . 2 . The insertion movement of the drill bit support  20  is limited by the support surfaces  23 . 2  that come to rest against corresponding counterpart surfaces of the tool sockets  13 . Then the fastening screw  12 . 2  can be inserted through the screw receptacle  12 . 1  and screwed into a threaded hole  21 . 1  of the insertion lug  21 .  FIG. 5  shows the joined pair of the insertion lug  21  and the tool socket  13 . As this drawing shows, the guide surfaces  22 . 1  rest against the flanks  13 . 3 . The convex outer surface  25  of the insertion lug  21  transitions flush into the convex outer sections of the guide projections  13 . 1 , thus avoiding an abrupt cross-sectional change in favor of a tool design that is optimized in terms of wear. 
         [0047]    As shown in  FIG. 5 , the guide projections  13 . 1  are spaced farther apart from the outer surface  25  than from the inner surface  24 , which is illustrated in  FIG. 5  with the dimensions a and b, where a is smaller than b. Correspondingly, there is a certain wear volume available in the region of or near the outer surface of the insertion lug  21 , which can wear down during use of the tool without significantly influencing the fastening region between the insertion lug  21  and the tool socket  13 . The cross-section of the insertion lug  21  is thus asymmetrical to its central transverse plane Q extending in the longitudinal direction of the insertion lug. Consequently, the tool sockets  13  are also asymmetrical. 
         [0048]    After all three drill bit supports  20  are fastened to the tool holder  10 , the drill head is ready for use. During engagement of the tool, the tool holder  10  and with it, the drill bit support  20 , rotates around the rotation axis R. As this occurs, the drill bits  30  come into engagement with the material to be removed. Because of the rotating motion, the drill bits  30  roll in the drilling hole and the hard material elements  34  cut into the material to be removed. An emulsion is supplied via the mud channel  15 , which is sprayed out in the region of the nozzle  15 . 1 . The emulsion flushes out the removed and crushed material, where the emulsion then flows out via the outlet channels  14 . 1 . The drill bits  30  are designed differently from one another in the region of or near their outer surface  31  so that the rotating rows of hard material elements  34  of one drill bit  30  can travel in a respective groove  32 ,  33  of the adjacent drill bit  30 . 
         [0049]    During engagement of the tool, the above-described tool combination experiences wear. Consequently, the drill bit  30 , the drill bit support  20 , and the tool holder  10  undergo continuous wear. Depending on the wear state, according to this invention, the tool holder  10 , the drill bit support  20 , and the drill bits  30  can each be individually replaced. For tool replacement, the drill head is detached from the drilling lance. To accomplish this, the screw connection between the fastening shank  11  and the drilling lance is disconnected. The drill bit support  20  can then be detached by simply unscrewing the fastening screw  12 . 2  from the tool holder  10 . The drill bit  30  can be pressed out from the drill bit support  20 . In the course of this, the clamping element  29 . 1 , due to the geometry of the grooves  26 . 5  and  35 , is deflected radially inward and thus disengages from the groove  35  of the drill bit  30 . The drill bit  30  can then be slid off of the drill bit support  20 . 
         [0050]      FIGS. 6 through 10  show another embodiment of an apparatus according to this invention. In it, parts that are the same have the same reference numerals so that in order to avoid repetitions, reference can be made to the descriptions above. 
         [0051]      FIG. 6  shows a drill head with a tool holder  10 , having the base part as a support structure  12 . The support structure  12  has a downward-pointing fastening shank  11  integrally formed onto it. The fastening shank  11  has a conical external thread. The support structure  12  is equipped with or has three tool sockets  13 , which protrude from the outside of the support structure  12  offset from one another by 120°. 
         [0052]      FIG. 9  clearly shows the tool socket  13 . As the drawing shows, the support structure  12  has one guide projection  13 . 1  for each tool socket  13 . Each guide projection  13 . 1  has longitudinal guides in the form of prism guides on opposite sides. The two prism guides are each formed by two guide surfaces  22 . 1  oriented at an angle relative to each other. An angle in the range between 45° and 75° between the guide surfaces  22 . 1  can be advantageous. This makes it possible to ensure a simple assembly in the rough conditions of worksite operations. In addition, this embodiment of the guide projections  13 . 1  does not have a tendency to jam. The guide surfaces  22 . 1  extend in the longitudinal direction of the guides, as shown in  FIG. 8  and  FIG. 10 . The drill bit supports  20  can be fastened to the tool sockets  13 . 
         [0053]    As shown in  FIGS. 8 and 10 , the tool supports  20  have a tool head  26 , which is integrally joined to an insertion lug  21 . On a radial inside, the insertion lug  21  forms a recessed fastening receptacle. In this case, the fastening receptacle is open toward the radial inside and in the downward direction, as shown in  FIG. 3 . The fastening receptacle is delimited by flanks  13 . 3  that are oriented relative to each other in prism fashion. The flanks  13 . 3  are oriented relative to each other at the same angle as the guide surfaces  22 . 1  so that the flanks  13 . 3  and the guide surfaces  22 . 1  form sliding guides. 
         [0054]    As shown in  FIG. 9 , the flanks  13 . 3  are part of guide pieces  22 , that delimit the fastening receptacle toward the front and the back in the advancing direction V. The guide pieces  22  each forms a respective shoulder  22 . 2 , which supports one of the flanks  13 . 3  and which engages in a form-locked way behind the guide projection  13 . 1 . As a result, the drill bit support  20  is not offset in the radial direction. Now, the drill bit support  20  can only be slid in the guidance direction. The two guide pieces  22  are connected to each other by a wall section  21 . 2 . In the attachment region to the tool holder  12 , the guide pieces  22  terminate at inner surfaces  24  that are flush with each other and are situated or positioned in one plane. The outside of the tool support  20  is defined by an outer surface  25  which is divided into a plurality of partial surfaces. In the advancing direction, the outer surface  25  has a first surface section  25 . 1  which transitions at an angle into a deflecting surface  25 . 2 . The deflecting surface  25 . 2  is tilted in the opposite direction from the advancing direction V, as shown in  FIGS. 8 and 9 . The deflecting surface  25 . 2  transitions via a clearing edge  25 . 6  into a side surface  25 . 3 . The clearing edge  25 . 6  extends essentially in the direction of the central longitudinal axis of the drill bit support  20 . In the opposite direction from the advancing direction V, the side surface  25 . 3  transitions at the back into an open surface  25 . 4 . Between the side surface  25 . 3  and the open surface  25 . 4  there is also an edge region. The open surface  25 . 4  finally ends at a surface section  25 . 5 , which like the surface section  25 . 1 , transitions into the inner surface  24 . 
         [0055]    As shown in  FIG. 8  and in  FIG. 10 , a fastening receptacle  21 . 3  in the form of a bore that passes through the two guide pieces  22  is located in the region of or near the insertion lug  21 . In order to mount the drill bit support  20  on the tool holder  10 , the flanks  13 . 3  of the drill bit support  20  in the region of or near its open underside are placed onto the guide surfaces  22 . 1 . Then, the insertion lug  21  of the drill bit support  20  is slid onto the guide projection  13 . 1  of the tool socket  13  in the guide direction. The sliding-on movement is limited by a stop  21 . 4  (see  FIG. 10 ). The stop  21 . 4  here is likewise embodied or shaped in the form of an internal prism in order to produce a form-locked engagement. This cooperates with corresponding prism surfaces of the guide projection  13 . 1 . In the installed state, the fastening receptacle  21 . 3  is flush with a corresponding bore receptacle in the guide projection  13 . 1 . Then a corresponding fastening element such as a hollow dowel pin can be slid through the flush fastening receptacles  21 . 3  of the insertion lug  21  and of the guide projection  13 . 1 . This prevents an offset of the tool support  20  relative to the tool holder  10  in the guidance direction. 
         [0056]    As shown in  FIG. 9 , the guide piece  22  toward the front in the advancing direction V has a larger wear volume than the rear guide piece  22 .  FIG. 9  also shows that the structural height of the front guide piece  22  in the radial direction is greater than the structural height of the rear guide piece  22  (distance dimension d 2 &gt;d 1 ). Consequently, the clearing edge  25 . 6  lies on a different, namely larger, pitch circle or center of the circle on the rotation axis R than the edge region between the open surface  25 . 4  and the side surface  25 . 3 . The side surface  25 . 3  thus has a wear-optimized geometry that decreases radially inward in the opposite direction from the advancing direction V, as shown in  FIG. 9 . 
         [0057]    The insertion lug  21  supports a tool head  26 , which has a bearing section  26 . 3  integrally formed onto it. 
         [0058]    The embodiment of the tool head  26  and drill bit  30  is selected to be similar or essentially identical to that of the embodiment according to  FIGS. 1 through 5 , so that reference can be made to the explanations above.