Abstract:
The present invention relates to a counter-blade, in particular, for a wood chipper, for producing wood chips, comprising at least one cutting edge made of a hard material, and a support surface leading to the cutting edge. According to the present invention, the cutting edge is made up of a plurality of hard material elements that are arranged next to one another along the cutting edge on a main member. This results in a counter-blade having a long service life.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/EP2014/079169 filed Dec. 23, 2014, which designated the United States, and claims the benefit under 35 USC §119(a)-(d) of German Application No. 10 2014 106 037.7 filed Apr. 30, 2014, the entireties of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a counter-blade, in particular, for a wood chipper, for producing wood chippings, having at least one cutting edge which is formed from a hard material and one support surface which leads to the cutting edge. 
       BACKGROUND OF THE INVENTION 
       [0003]    Shredding units, where rotating cutters are moved past a fixedly located counter-blade and the material is shredded between the rotating cutters and the counter-blade, are used for the shredding of biomaterials, for example, in agriculture or forestry, but also for the shredding of waste. Thus, DE 44 02 111 A1 describes a mobile waste shredding unit for reducing the volume of, for example, bulky waste, demolition wood, plastics materials and old tires as well as for organic waste materials, such as green cuttings, weak wood, etc. The shredding unit consists of a slow-running, cylindrical rotor, on which the cutters are mounted, and a beam-like counter-cutter arranged parallel to the rotor. The material to be shredded is fed to the shredding unit by means of a draw-in unit. 
         [0004]    The cutters and the counter-blade are exposed to a high degree of wear are consequently replaceable. In order to obtain a long service life of the counter-blade, AT 398 509 B describes, for its use in a cutting machine, a cutting strip, the cutting edge of which is formed by two cutting surfaces (side face and top surface) which are located approximately at right angles to each other. Consequently, the side face is provided up to the cutting edge with a coating produced from a hard metal. A hard metal coating is also provided on the top surface, at a spacing from the cutting edge. 
         [0005]    As a result of the hard metal coating, the service life of the counter-blade can be significantly increased. In this case, the gap between the cutting edge and the coating on the top surface brings about a self-sharpening effect as the softer material located in between wears more intensely whilst the cutting edge formed from hard material remains unchanged. 
         [0006]    In the case of a hard metal, as a brittle material there is the risk of fracture when the counter-blade is stressed, for example, as a result of a material that is fed being very hard. The fracture, in this case, can run over the complete length of the counter-blade and as a result make the counter-blade unusable. However, even locally delimited outbreaks in the hard metal coating can result in the entire counter-blade having to be replaced prematurely as the desired cut size is no longer obtained overall. 
       SUMMARY OF THE INVENTION 
       [0007]    It is consequently the object of the present invention to provide a counter-blade which has a long service life and additionally enables simple mounting. 
         [0008]    The object of the present invention is achieved as a result of the cutting edge being formed from a plurality of hard material elements which are arranged on at least one basic body one next to another along the cutting edge. 
         [0009]    The hard material elements, in this case, can preferably be produced from a hard metal. Such hard material elements show a very small level of wear, as a result of which the service life of such a counter-blade is significantly extended compared to a conventional counter-blade produced from steel. The realization of the cutting edge from a plurality of hard material elements arranged one next to the other provides the advantage that in the case of a possible fracture of one hard material element, the fracture does not run further into an adjacent hard material element. The damage, consequently, remains locally delimited such that it is possible to continue to use the counter-blade. Over and above this, in the case of a counter-blade edge that is segmented in this manner, a stress-optimized design in favor of a low risk of fracture can be achieved. The fastening of the hard material elements on the basic body is effected in short segments such that, for example, fastening irregularities due to tolerances only have a small influence on the component stresses introduced by means of the fastening. As the hard material elements are mounted on a basic body, the basic body, in the case of mounting or in the case of a necessary replacement, is able to be mounted simply and quickly in one operation together with the attached hard material elements. The use of small hard material elements provides the further advantage that they are able to be produced in a cost-efficient manner and in large quantities. As a result, the overall costs for a counter-blade provided with hard material can be kept down. 
         [0010]    As already mentioned above, hard metal is suitable as the material for the hard material elements. Particularly suitable, in this case, are hard metals which have a cobalt content of between 3.0 and 25 percent by weight. In this case, a material composition which has a grain size in the hard metal material within the range of between 10 μm and 30 μm is particularly suitable. Such materials are particularly impact resistant and are suitable in a specific manner for wood shredding or the shredding of recycling materials. 
         [0011]    Corresponding to a particularly preferred development variant of the present invention, it can be provided that in each case part of the hard material elements is arranged along an edge of the basic body and that the cutting edge is formed by the hard material elements of basic bodies arranged next to one another. A long counter-blade can consequently be formed by placing a plurality of basic bodies provided with hard material elements next to one another a row. In this case, standard basic bodies can be used in the manner of a construction kit to produce counter-blades of different lengths. The use of smaller, standard basic bodies provides the advantage that they are able to be used in a cost-efficient manner in smaller production units. A production error, for example, when soldering, leads simply to the rejection of one basic body and not of a whole counter-blade. In operation the advantage of designing the counter-blade from a plurality of basic bodies is that, where required, they are able to be replaced individually. Thus, for example, where the stress on the counter-blade is uneven, the basic bodies arranged in portions of the counter-blade that are particularly highly stressed and are correspondingly worn are able to be replaced prematurely whilst the basic bodies in less stressed regions continue to be used. Damaged basic bodies are able to be replaced individually in a corresponding manner. 
         [0012]    A suitable cutting edge with good cutting results can be obtained as a result in that the hard material elements are configured in a cuboid or trapezoidal manner, that in each case a long edge of the cuboid or trapeze forms part of the cutting edge and that the cuboids or trapezes are arranged next to one another in a row along their surface delimited by their short edges. The cuboid hard material elements are able to be produced in a cost-efficient manner in large quantities and can easily be joined to the basic body, for example, by means of hard soldering. To this end, an arbitrary number of hard material elements can be placed in a row flush next to one another. As a result of the cuboid form, the material use of the high-quality hard material can be adapted optimally to the requirements such that the basic body, the hard material elements and further wear components of the counter-blade have approximately the same service life. 
         [0013]    A more secure and durable fastening of the hard material elements on the basic body can be achieved it that along the cutting edge the basic body comprises a recess into which the hard material elements are admitted in a flush manner to form a front end face of the basic body and/or in a flush manner to form the support surface or that the hard material elements are admitted in such a manner into the recess that they project beyond the front end face and/or the support surface or that the hard material elements are admitted in such a manner into the recess that they are set back in relation to the support surface. The preferably cuboid hard material elements are consequently joined to the basic body in each case on two of their long sides such that they are not broken out of the bond even in the event of strong mechanical stress. If the hard material elements end flush with the support surface or if they are set back somewhat in relation to the support surface, they are not contacted by the material to be cut, which is fed over the support surface under an introduced pressing pressure, and sheared off by the basic body. If the hard material elements are arranged such that they end flush with the end face of the basic body or project somewhat beyond the end face of the basic body, a free cut surface is formed. The support for the hard material elements formed by the recess ends, in the case of this arrangement, flush or set back with respect to the hard material elements and is correspondingly protected from the passing material to be cut, as a result of which premature wear of the basic body is able to be avoided in this region. 
         [0014]    Along with the cutting edge itself, the support surface, along which the material to be cut is fed to the cutting edge, is also exposed to great mechanical stresses in the direct vicinity of the cutting edge. In order to avoid increased wear on the basic body in the region, it can be provided that, along the hard material elements forming the cutting edge, the support surface comprises a plurality of protective elements which are arranged in a row next to one another, are produced from hard material and preferably join in a flush manner to the hard material elements or are arranged at a spacing of a gap from the hard material elements. The protective elements can be produced, for example, from abrasion-resistant hard metal. If the protective elements abut directly against the hard material elements, the top surface of the basic body is completely protected against wear in the region. The basic body being eaten away, which would result in weakening the support of the hard material elements, can consequently be prevented here. Following such erosion, there would be the risk of the hard material elements breaking prematurely. If a gap is provided between the hard material elements and the protective elements, the relatively soft material of the basic body is exposed here. As a result of increased abrasion in the region, the rear sides of the hard material elements are slowly exposed in operation, whilst the hard material elements are worn in a slower manner. The hard material elements form a free-standing cutting edge as a result. A self-sharpening effect for the cutting edge can be achieved in this manner as a result of the arrangement. In order to prevent excessive erosion of the basic body in this case, the gap region has to be dimensioned in dependence on the strength of the basic body. 
         [0015]    The risk of breakage for the hard material elements and the protective elements can be further reduced in that the transitions between the protective elements are arranged in the direction of extension of the cutting edge so as to be spatially offset with respect to the transitions between the hard material elements. 
         [0016]    The hard material elements are exposed to greater mechanical stress and consequently greater wear than the protective elements. In order to achieve a comparable service life for the hard material elements and the protective elements, it can be provided that, proceeding from the basic body, the material thickness of the hard material elements is chosen to be greater than the material thickness of the protective elements. 
         [0017]    When the counter-blade is in use, it can occur that certain regions, for example, in the center of the counter-blade, are stressed mechanically more intensely and more frequently than other regions, for example, at the edge of the counter-blade. In the regions under the greater mechanical stress, there is increased wear on the counter-blade as a result. In order to achieve a comparable service life of the basic body and of the attached hard material elements and the protective elements over the entire length of the counter-blade, it can be provided that the material thickness of the hard material elements and/or the material thickness of the protective elements is chosen to be different for various basic bodies. In the regions under great mechanical stress, basic bodies can thus be provided with comparatively thick hard material elements or protective elements, whilst in regions of lower mechanical stress basic bodies can be provided with thin hard material elements or protective elements. 
         [0018]    The material to be cut is guided over the support surface to the cutting edge under a high pressing pressure. In order to protect the basic body from wear in the region, it can be provided that the support surface is formed by in each case one cover plate which is mounted on each basic body and is joined directly or indirectly to the protective elements or the cutting edge. If the cover plate is worn prematurely compared to the hard material elements or the protective elements, it can be replaced separately and the basic body with the high-quality hard material components can continue to be used. 
         [0019]    The basic body can preferably be formed from a comparatively soft and tough steel and the cover plate can be formed from a steel that is comparatively harder in relation thereto. The soft, tough steel of the basic body maintains its characteristics at the necessarily high temperatures during the soldering process for the attachment of the hard material elements and of the protective elements and brings about a high bending and tensile strength of the basic body when the counter-blade is in use. The comparatively hard cover plate produces the necessary low amount of wear on the support surface. The basic body can be produced, for example, from 42CrMo4, whilst the support surface can be produced from Hardox 400. 
         [0020]    To position the protective elements during the soldering process during production and the cover plate when it is being mounted, it can be provided that the basic body realizes a web between the protective elements and the cover plate. The protective elements can be fixed on the web during production. The web forms a reservoir for the solder used such that it does not flow away. For the subsequent mounting of the cover plate, the cover plate can be placed onto the web. In this way, it is correctly aligned for fastening on the basic body. 
         [0021]    In order to achieve as full a contact between the cover plate and the basic body as possible, it can be provided that the basic body, on the side remote from the cutting edge, realizes a support plane along which the cover plate is held in a flat manner. As a result of the full contact, breakage or deformation of the cover plate is avoided even in the case of great mechanical stress. The transition from the web to the support plane is preferably realized as a rounding and an edge of the cover plate has a chamfer in the region of the rounding. The rounding reduces stress peaks in the region of the transition from the web into the support plane. The achievement of the chamfer is that the cover plate is located freely in the region of the rounding and consequently rests over its entire surface along the support plane. 
         [0022]    In order to be able to join the basic body securely and quickly to a carrier and the cover plates in each case to a basic body, it can be provided that the basic body comprises fastening receiving means for receiving fastening elements for fastening the basic body onto a carrier and that the cover plate comprises bores for receiving mounting screws for fastening the cover plate on the basic body, wherein in the mounted state the cover plate covers the fastening receiving means of the basic body. The fastening receiving means of the basic body are thus protected from wear by the cover plate. 
         [0023]    For mounting the counter-blade, the basic bodies are first of all fastened on a carrier and the cover plates are then mounted on the basic body. The dismantling is effected in the reverse order. On account of contamination, for example, as a result of resinification, it can occur that the cover plate cannot be released from the basic body when being dismantled. Consequently, it can be provided that the cover plate comprises a forcing portion, preferably a threaded bore. The cover plate can be forced from the basic body by way of the forcing portion and can consequently be released. A simply producible realization, in this case, is provided by a threaded bore which penetrates the cover plate. For dismantling, a screw, which presses on the basic body located below it and lifts the cover plate from the basic body, can be rotated in the threaded bore. 
         [0024]    In an alternative development of the present invention, it can be provided that the basic body comprises a second cutting edge. The second cutting edge can be formed correspondingly to the first cutting edge from hard material elements which are arranged in a row one next to another, preferably of the same hard material elements as are used for the first cutting edge. Counter-blades with two cutting edges can be formed from the basic bodies, as are used in the case of various shredding units. 
         [0025]    Corresponding to a particularly preferred realization variant of the present invention, it can be provided that the basic body comprises a positioning receiving means or a positioning attachment for receiving a positioning attachment or a positioning receiving means arranged on the carrier. When the basic body is mounted, the positioning attachment engages in the positioning receiving means. As a result, the position of the basic body is set and fixed in relation to the carrier. This is, in particular, advantageous when replacing a basic body during an assignment of the shredding unit as the replacement can be carried out quickly and correctly even under unfavorable conditions and the assembly times of the unit can thus be kept very short. 
         [0026]    Simple positioning of the basic body in relation to the carrier can be achieved in that the positioning receiving means or the positioning attachment is arranged along an end-face stop surface of the basic body located opposite the cutting edge or that the positioning receiving means or the positioning attachment is arranged along a mounting plane of the basic body located opposite the support plane. For mounting, the basic body is placed in such a manner onto the carrier that the positioning attachment engages in the positioning receiving means such that the basic body is able to be joined to the carrier by means of the fastening elements. 
         [0027]    In order also to be able to align and mount the cover plate quickly and securely in relation to the carrier and to the basic body mounted thereon, it can be provided that cover plate comprises a positioning receiving means and/or a positioning attachment on its end face remote from the cutting edge. The positioning attachment then engages in a corresponding positioning receiving means on the carrier, or a positioning attachment provided on the carrier engages in the positioning receiving means of the cover plate such that the cover plate is aligned precisely on the basic body. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0028]    The present invention is explained in more detail below by way of an exemplary embodiment shown the drawings, in which: 
         [0029]      FIG. 1  shows a top view of a counter-blade  10  with one cutting edge; 
         [0030]      FIG. 2  shows a perspective front view of a basic body of the counter-blade with a cutting edge portion; 
         [0031]      FIG. 3  shows the representation according to  FIG. 2  as an exploded drawing with a cover plate; 
         [0032]      FIG. 4  shows a top view of a segment of the counter-blade; 
         [0033]      FIG. 5  shows a side view of the segment of the counter-blade shown In  FIG. 4 ; and 
         [0034]      FIG. 6  shows a second segment of a counter-blade with two cutting edges. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0035]      FIG. 1  shows a top view of a counter-blade  10  with one cutting edge. 
         [0036]    The cutting edge  14  is formed from a row of cuboid hard material elements  12  which are arranged along the cutting edge  14 . Protective elements  13 , offset in relation to the hard material elements  12 , are arranged joining directly to the hard material elements  12 . The protective elements are also formed from a hard material. In the exemplary embodiment shown, the hard material elements  12  and the protective elements  13  are produced from hard metal. Separated by a narrow web  28 , following the protective elements  13 , cover plates  30  are fastened, each with two mounting screws  34 , on in each case one basic body  20  which is concealed by the cover plates  30 , the protective elements  13  and the hard material elements  12 , as is shown in  FIGS. 2, 3 and 5 . The hard material elements  12 , together with the cover plates  30  and the web  28  arranged in between, form a support surface  29  which leads to the cutting edge  14 . 
         [0037]    With the protective elements  13  and hard material elements  12  arranged in rows thereon, a cover plate  30  shows the outline of a segment  16  of the counter-blade  10 . The counter-blade  10  is formed, in the exemplary embodiment shown, from eight segments  16  arranged in a row next to one another. The segments  16  are fastened on a carrier  11  for this purpose. In each case six hard material elements  12  per segment  16  form, in this case, a cutting edge portion  18  which is marked by a double arrow, the cutting edge portions  18  which are arranged in a row next to one another provide the cutting edge  14 . 
         [0038]    Along a stop face  15 , against which the segments  16  abut at the rear on a corresponding wall of the carrier  11 , the carrier comprises positioning attachments  17 . The positioning attachments engage in positioning receiving means  23 ,  35  mounted on the basic body  20  and the cover plate  30 , as is shown in more detail in  FIGS. 2 and 4 . 
         [0039]    A continuous threaded bore  33  is provided in each cover plate  30  between the mounting screws  34 . 
         [0040]    During mounting, the basic bodies  20  are fastened on the carrier  11  in such a manner that the cutting edge  14  protrudes beyond the carrier  11 . In this case, the positioning attachments  17  and the positioning receiving means  23  serve for the quick and precise alignment of the individual basic bodies  20  in relation to the carrier  11 . The cover plates  30  are then mounted on the basic bodies  20 . Here too, the second positioning receiving means provided on the cover plate  30  serves for the simple positioning of the cover plate  30  in relation to the carrier  11  and consequently in relation to the already mounted basic body  20 . Provided with the segments  16  of the counter-blade  10 , the carrier  11  can then be mounted, for example, on a wood chipper to create wood chippings, in such a manner, that the cutting edge  14  is located opposite cutters which are arranged on a rotating roller of the wood chipper and are moved past the counter-blade  10 . 
         [0041]    In operation, the wood to be shredded is fed by corresponding conveyor units beyond the support surface  29  to the cutting edge  14 . The cutters of the wood chipper (not shown) are moved past the cutting edge  14  coming from the viewing direction in the representation. Wood which protrudes beyond the cutting edge  14  is shredded in this case. 
         [0042]    The cutting edge  14  is advantageously formed from a plurality of hard material elements  12 . Hard material elements  12  show a low amount of wear, as a result of which a long service life of the counter-blade  10  is achieved. As a result of the small size of the individual hard material elements  12 , the bending stress of the individual hard material elements  12  is low such that fractures are able to be extensively avoided. Should a hard material element  12 , nevertheless break, for example, caused by great mechanical stress by a hard material inadvertently being introduced into the cutting gap, the breakage is limited to the relevant hard material element  12  and does not progress further into the adjacent hard material element  12 . As a result of the design of the counter-blade  10  from a plurality of adjacently arranged hard material elements  12 , an extended breakage along the cutting edge  14  formed from hard metal can consequently be avoided and the counter-blade  10  can continue to be used. If, nevertheless, there is greater damage to a cutting edge portion  18  or if a cutting edge portion  18  is worn prematurely as a result of irregular stress along the cutting edge  14 , the relevant segment  16  is able to be individually replaced. To this end, firstly the cover plate  30  is separated from the basic body  20  and then the basic body  20  is separated from the carrier  11 . If the cover plate  30  cannot be separated from the basic body  20 , for example, on account of heavy contamination or resinification, a screw can be screwed into the threaded bore  33  and, as a result, the cover plate  30  can be pressed away from the basic body  20 . A new basic body  20  can then be mounted onto the carrier  11  at the free position and a cover plate  30  can be attached. As a result of simple centering by means of the positioning receiving means  23 ,  35  and the positioning attachments  17 , one or several segments  16  can be changed very rapidly. Together with the long service life, which corresponds to between ten and twelve times the service life of a normal steel counter-blade, very few maintenance-related machine stoppages can thus be achieved. As a result of being able to replace individual segments  16 , the spare parts costs can be kept low. The small amount of wear of the hard material elements brings about a constant cutting performance of the counter-blade  10  over a long period of time. This leads to constant quality of the chipped material. In addition, as a result of the high cutting performance, lower energy consumption and consequently reduced operating costs are achieved for the shredding unit. This is noticeable, in particular, in mobile usage by reduced fuel consumption, which along with reduced costs also leads to less environmental pollution. 
         [0043]    The front region of the support surface  29 , which faces the cutting edge  14  and is under particular mechanical stress, is also protected from premature wear by the protective elements  13 . As a result of using a plurality of protective elements  13  arranged in rows next to one another and as a result of the lateral offset in relation to the hard material elements  12  arranged in front thereof, the risk of breakage is reduced here too and a breakage is prevented from spreading further. 
         [0044]      FIG. 2  shows a perspective front view of a basic body  20  of the counter-blade  14  with a cutting edge portion  18 . 
         [0045]    The basic body  20  is produced from a relatively soft, tough steel, for example, from 42CrMo4. In the front region it forms a supporting part  25 , on which the hard material elements  12  and the protective elements  13  are soldered. A recess  26 , into which the cuboid hard material elements  12  are admitted, is formed toward a front end face  21 . 2  in the supporting part  25 . The front sides of the hard material elements  12 , in this case, end with the front end face  21 . 2  of the basic body and, proceeding from the cutting edge portion  18 , form a cutting surface  27 . The top surface of the hard material elements  12  ends flush with the top surface of the protective elements  13  which join to the hard material elements  12 . The top surface of the protective elements  13  forms a portion of the support surface  29 . The protective elements  13  are arranged flush between the hard material elements  12  and the web  28 . The web  28 , in this case, serves for positioning and mounting the protective elements  13 , in particular, during the soldering process during production. 
         [0046]    A support plane  21 . 1 , which is placed in a recessed manner compared to the support of the protective elements  13 , is provided following the web  28 . Proceeding from the support plane  21 . 1 , the basic body  20  is penetrated by three fastening receiving means  22 , which are realized as counter bores and are arranged offset, and two threaded receiving means  24 . 
         [0047]    The basic body  20  is delimited at the side by two side faces  21 . 3  which extend in a plane-parallel manner and on which the basic bodies  20  are located next to one another in their arrangement on the carrier  11 . 
         [0048]    At the rear, the basic body  20  ends in a rear end-face stop face  21 . 4 , in the center of which the positioning receiving means  23  is preferably recessed as a wedge-shaped recess. 
         [0049]    The basic body  20  consequently forms the basis for a segment  16  of the counter-blade  10 . The basic body  20  can be mounted simply and securely on the carrier  11  by means of the fastening receiving means  22  with the aid of screws. As a result of the countersinking applied on the fastening receiving means  22 , the screws can be arranged in a recessed manner such that they do not protrude beyond the support plane  21 . 1 . A cover plate  30  shown in  FIG. 1  can thus be placed onto the support plane  21 . 1  of the basic body  20  and tightened at the threaded receiving means  24 . 
         [0050]    The soft steel used maintains its characteristics during the process of soldering the hard material elements  12  and the protective elements  13 . 
         [0051]      FIG. 3  shows the representation according to  FIG. 2  as an exploded drawing with a cover plate  30 . The cover plate  30 , in this case, is arranged above the basic body  20  described in  FIG. 2 . Proceeding from its top surface, it is penetrated by two countersunk bores  32 , with which two mounting screws  34  are associated. In addition, the threaded bore  33  is guided through the cover plate. 
         [0052]    The dimensions of the cover plate  30  are chosen so as to match the dimensions of the support surface  21 . 1  of the basic body  20 . The bores  32  are arranged in such a manner that, with the cover plate  30  placed in position, they are aligned with the threaded receiving means  24  of the basic body  20 . The mounting screws  34  can thus be guided through the bores  32  and screwed into the threaded receiving means  24 . As a result, the cover plate  30  is fixedly joined to the basic body  20 . 
         [0053]    In the mounted state, the screw heads of the mounting screws  34  are arranged countersunk in the cover plate  30 . The top surface of the cover plate  30  consequently forms, with the connecting web  28  and the top surface of the protective elements  13 , a continuous, flat support surface  29 , along which the material to be cut can be fed to the cutting edge portion  18  and consequently to the cutting edge  14 . 
         [0054]    The fastening receiving means  22  and the screws inserted therein for mounting the basic body  20  onto the carrier  11  are covered by the cover plate  30  and as a result are protected from wear. The cover plate  30  itself is produced from a steel which is harder when compared with the basic body  20  but is nevertheless tough, for example, from Hardox 400. As a result, the support surface  29  is realized in a continuously wear-protected manner. Should the cover plate  30  nevertheless wear prematurely or become damaged, it can be replaced separately and the high-quality hard metal components can continue to be used. 
         [0055]      FIG. 4  shows a top view of a segment  16  of the counter-blade  10  in the assembled state. The cover plate  30  is held in the basic body  20  by the mounting screws  34  which are arranged in a countersunk manner. It ends toward the protective elements  29  on the web  28 . The top surface of the segment  16  consequently forms a continuous support surface  29  up to the cutting edge portion  18 . On the side of the cover plate  30  remote from the web, the second positioning receiving means  35  is molded in the form of a wedge-shaped recess. This extends congruently with respect to the positioning receiving means  23  of the basic body  20  which is located below it. The segment  16  can consequently be aligned simply and quickly in a positionally precise manner in relation to the carrier  11  by the positioning receiving means  23 ,  35  of the basic body  20  and of the cover plate  30  being slid onto a positioning attachment  17  of the carrier  11 . 
         [0056]      FIG. 5  shows a side view of the segment  16  of the counter-blade  10  shown in  FIG. 4  along a line of intersection marked by way of V-V in  FIG. 4 . 
         [0057]    The cover plate  30  is held on the basic body  20  by way of the mounting screw  34 . In the transition from the web  28  to the support plane  21 . 1 , the basic body  20  forms a rounding  28 . 1 . The edge of the cover plate  30  shows a first chamfer  31 . 1  in the region of the rounding  28 . 1  such that the cover plate  30  is able to be placed flush onto the support plane  21 . 1  of the basic body  20 . As a result of the rounding  28 . 1 , stress peaks are reduced in the region of the transition from the web  28  into the support plane  21 . 1 . 
         [0058]    The cover plate  30 , the web  28 , the protective elements  13  and the hard material elements  12  form a continuous support surface  29  which, in the mounted state, merges in a flush manner into a corresponding surface of the carrier  11 . The material to be cut can consequently be fed via the surface of the carrier  11  and the support surface  29  to the cutting edge portion  18  and consequently to the cutting edge  14 . A second chamfer  31 . 2  is provided on the cover plate  30  in the transition from the support surface  29  to the corresponding surface of the carrier  11 . The second chamfer prevents, for example, on account of production tolerances or abrasion of the carrier  11 , a step being formed between the surface of the carrier and the support surface  29 , on which more wear then occurs as a result of the material to be cut being guided over it. As an alternative to the second chamfer  31 . 2 , the edge of the cover plate  30  can also be realized rounded over a radius. A particularly break-resistant edge which withstands very great stresses is obtained as a result of a radius. 
         [0059]    A basic body bottom surface  21 . 5  of the basic body  20  is realized as a flat surface which is arranged in a plane-parallel manner with respect to the support surface  29 . The basic body  20  is able to rest thereon along a mounting plane on a corresponding counter surface of the carrier  11 . 
         [0060]      FIG. 6  shows a second segment  49  of a second counter-blade (not shown) with two cutting edges. 
         [0061]    A second basic body  40  is realized as a substantially elongated cuboid. Along two oppositely situated long edges of the cuboid, the second basic body  40  comprises a front recess  46 . 1  and a rear recess  46 . 2  into which front hard material elements  41 . 1  and rear hard material elements  41 . 2  are inserted. In each case a row of front protective elements  42 . 1  and rear protective elements  42 . 2 , which are also produced from a hard material, are arranged joining to the hard material elements  41 . 1 ,  41 . 2 . In the exemplary embodiment shown, the front and rear hard material elements  41 . 1 ,  41 . 2  and the front and rear protective elements  42 . 1 ,  42 . 2  are produced from hard metal. A second web  45 , which is integrally molded onto the second basic body  40 , is arranged between the rows of the protective elements  42 . 1 ,  42 . 2 . Second fastening receiving means  44  in the form of stepped bores, which penetrate the basic body  40 , are provided along the second web  45 . The top surfaces of the front and rear hard material elements  41 . 1 ,  41 . 2 , of the front and rear protective elements  42 , 1 .  42 . 2  and of the second web  45 , form a flat second support surface  47 . The front and rear holding elements  41 . 1 ,  41 . 2  provide a front cutting edge portion  43 . 1  and a rear cutting edge portion  43 . 2 . 
         [0062]    The second basic bodies  40  can be arranged in a row one next to another on a carrier (not shown) and joined to the carrier by way of screws which are guided through the second fastening receiving means. For secure positioning of the second basic bodies  40 , positioning attachments or positioning receiving means which engage in corresponding positioning receiving means or positioning attachments of the carrier, can be provided on the bottom surface of the second basic bodies. The bottom surface of the second basic body  40  forms with the top surface of the carrier a mounting plane in which the positioning receiving means and positioning attachments are arranged. The second basic bodies  40  each comprise two short-side end faces  48  which are realized in a flat manner such that the second basic bodies  40  are able to be arranged flush in rows next to one another on the carrier. The front and rear cutting edge portions  43 . 1 ,  43 . 1  of the second segments  49  which are arranged in rows next to one another form a front and a rear cutting edge of the second counter-blade. 
         [0063]    In operation, cutters are moved past each of the two cutting edges. Material to be cut which is introduced into the region of the cutting edges is thus shredded between the cutting edges and the cutters moving past. 
         [0064]    In the realization variant too, the inserted small hard material elements  41 . 1 ,  41 . 2  and protective elements  42 . 1 ,  42 . 2  result in a long service life of the second counter-blade. Breakages in one of the hard metal components are not passed onto the next hard metal component. When required, individual second segments  49  can be replaced quickly. In this case, the positioning receiving means and positioning attachments mounted in the mounting plane between the bottom surface of the second basic body  40  and the carrier enable quick and precise positioning of the replacement segments. 
         [0065]    In an alternative embodiment (not shown) of the representations shown in  FIGS. 1 to 5 , the cover plates  30  can be arranged offset to the side in such a manner with respect to the basic bodies  20  that the abutment edges between the basic bodies  20  arranged in a row next to one another, formed along the side faces  21 . 3 , are covered by the cover plates  30 . A cover plate  30  is then screwed at one of its bores  32  with a first base plate  30  and at its second bore  32  with an adjacent second base plate  30 . In each case, the outermost of the base plates  30  arranged on a counter-blade  10  are realized in a shortened or lengthened form, for example, with half a width or one and a half widths of a basic body  20  measured in the direction of the longitudinal extension of the counter-blade. Advantageous in this connection is that a continuous gap, into which waste material can be pressed, is not formed up to the carrier  11  between the cover plates  30  and the basic bodies  20 .