Abstract:
A tool unit for a comminution device with a rotor-stator system is provided, in which comminution tools are detachably fastened to tool holders on a rotor circumference and work together with comminution tools located on the stator. In order to shorten the tool replacement downtimes of a device equipped with such a tool unit and to increase its profitability, the tool holder includes a first carrier section and a second carrier section, the rear sides of which sections detachably contact one another in a common contact plane, and on each of the mutually averted front sides of which is located at least one bearing surface for accommodating a tool.

Description:
This nonprovisional application claims priority under 35 U.S.C. §119(a) to German Patent Application No. DE 10 2011 119 589.4, which was filed in Germany on Nov. 29, 2011, and which is herein incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a tool unit for a comminution device, a cutting or punching tool, and a device therefor. 
     2. Description of the Background Art 
     From DE 195 37 581 A1, a cutter arrangement for a comminution device is known in which the square blades are attached at the rotor circumference by blade holders. To this end, the blade carriers have a front side pointing in the direction of rotation that the rear side of the blade rests against. The blades are clamped against the blade carriers with the aid of mounting screws, which engage a threaded hole in the blade through holes in the blade carrier from the back. A first disadvantage of this type of cutter arrangement is that all blades have to be replaced individually on the standing rotor. Because of the large number of blades to be replaced, the associated amount of work requires relatively long downtimes. Blade replacement is further complicated by the fact that the mounting screws run tangentially, requiring a driving tool to be placed in the same orientation. However, the space available in the tangential direction towards the rotor is limited for construction reasons, so that it is only possible to manipulate devices such as impact drivers and the like with difficulty, if at all. It has further proven to be a disadvantage that comminution of the feed material is only possible in one direction of rotation of the rotor, which results in asymmetrical wear. 
     SUMMARY OF THE INVENTION 
     As alluded to above, the invention relates generally to the field of mechanical process engineering, and within this field more particularly in the comminution of solid, free-flowing materials. A preferred field of application resides in the processing of waste materials or the recovery of useful materials during the course of recycling. Plastics, rubber, wood, wood waste, paper, cardboards, textiles, collections from waste collection, and the like, are mentioned by way of example as possible feed material. A not inconsiderable wear of the comminution tools is associated with the comminution of such materials, and these tools must regularly be replaced by new ones in consequence. The attendant machine downtimes substantially determine the profitability of the comminution operation. 
     It is therefore an object of the invention is to reduce the downtimes of a comminution device required for tool changing, and in this way to increase the profitability of the comminution process. 
     The invention is based on the basic concept of arranging multiple processing tools, such as blades for example, on a tool holder that is detachably fastened to the rotor, wherein the resultant tool unit can be manipulated as a whole during replacement of the tools. Thus, when a tool unit is replaced, a plurality of tools are replaced at once. In this concept, moreover, loading of the tool holder can be performed outside the device while operation is ongoing, so that the time required for tool replacement can be concentrated in the exchange of comparatively few tool units. In this way, downtimes required for tool changing are reduced considerably. 
     According to the invention, the individual blade carriers are divided into two parts, wherein the front side of each carrier section accommodates the tools and the rear side of it contacts the rear side of the other carrier section. Since the carrier sections preferably are identical in structure, any two desired carrier sections equipped with tools can be put together to make a tool unit. Consequently, the number of different components, and hence the required supply, is very small. 
     The symmetry arising upon assembly of the tool units opens up many possibilities for being able to undertake a tool replacement extremely effectively. Because of the symmetrical arrangement of the tools with respect to the contact plane of the two carrier sections, a tool unit can be rotated by 180° about a radially oriented axis after having been removed from the seat, and then be attached to the rotor again. In this way, the tools that previously were in the lee of the motion are moved to the tool unit&#39;s front side pointing in the direction of rotation, with the rotor&#39;s direction of rotation remaining the same. The same effect can be achieved by changing the rotor&#39;s direction of rotation instead of rotating the tool units. In this way, the device is switched over to unused tools without the need to perform work on the rotor. The service life of the rotor can be doubled in this way, which means that the downtimes are cut in half. 
     If the tools are attached to the carrier sections using mounting screws, then the ends of the mounting screws opposite the screw heads can advantageously be located in recesses on the rear side of the carrier sections. This ensures unhindered full-area contact of the two carrier sections with one another, while also ensuring that the ends of the mounting screws that are critical for removing the tools are protected from the effects of mechanical forces during comminution operation. In this way, the fastening component in the anchoring region remain undamaged and can thus be removed. 
     In order to be able to join the two carrier sections together with a precise fit and install them in the rotor in this position, interlocking components are advantageously arranged in the common contact plane carrier sections. In addition to the centering of the two carrier sections achieved in this way, the interlocking components, such as, e.g., feather keys or dowel pins, hold the two carrier sections together to a certain degree due to the frictional connection with the keyway or dowel hole, which facilitates handling thereof during tool replacement without notably hindering the disassembly of a tool unit. 
     In an embodiment of the invention, provision is made for two adjacent bearing surfaces of a carrier section to be arranged with an offset perpendicular to the bearing surface. Consequently, the tools also have this offset, so that the tools of a tool unit do not all engage the feed material at the same time, but rather successively during the course of the rotor&#39;s rotation. The resistance provided by the feed material is evened out in this way, and peak loads are reduced. A comparable effect can be achieved if the bearing surfaces for the processing tools run at an angle to the longitudinal extent of the carrier section. 
     Fastening devices can include, for example, bolts, screws, etc. wherein the screw head rests, for its protection, in a countersunk hole in the tool. Preferably, the conical inner surface of the countersunk hole is also designed to be convex, resulting in annular contact of the screw head in the countersunk hole. In this way, angular tolerances of the mounting screw can be compensated without jamming occurring. 
     In an embodiment of the invention, recesses that form seats are arranged in the outer surface of the rotor for attaching the tool units. A tool unit is inserted radially in a seat, where it is clamped tangentially against a wall of the seat by means of a clamping wedge. In this process, the clamping wedge is clamped radially against the bottom of the seat by means of a clamping screw. In this type of fastening method, therefore, the clamping screw is radially accessible and thus can be removed quickly and easily with no limitations on freedom of movement. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein: 
         FIG. 1  is a cross-section through a device according to the invention along the line I-I shown in  FIG. 2 ; 
         FIG. 2  is a longitudinal section through the device shown in  FIG. 1  along the line II-II therein; 
         FIG. 3  is an oblique view of a tool unit according to the invention; 
         FIG. 4  is a side view of the tool unit shown in  FIG. 3 ; 
         FIG. 5  is a cross-section through the tool unit shown in  FIG. 4  along the line V-V therein; and 
         FIG. 6  is a larger scale view of the area labeled VI in  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show the invention in an overview. The device shown has an essentially symmetrical structure based on a machine base frame with two opposing, plane-parallel transverse walls  1 , which are connected to one another at their bottom corners by bottom longitudinal spars  2 , and at their top corners by top longitudinal spars  3 . The longitudinal walls  4  are composed over their full area of doors  5 , which can pivot on hinges  6  in order to open and close the housing, thus ensuring accessibility to the interior of the device. 
     Welded to the outside of each of the two transverse walls  1  is a bracket  7  for accommodating a shaft bearing  8 . The shaft bearings  8  carry a rotor  9 , which is composed essentially of a rotor drum  11 ; a stub shaft  10  engages each end face of the drum in a rotationally fixed manner. The free ends of the two stub shafts  10  extend through openings in the transverse walls  1  as far as the shaft bearings  8 . The rotor  9  is equipped over its circumference with a plurality of tool units  12 , which are spaced apart from one another both in the circumferential direction and in the axial direction. In this design, each tool unit  12  is replaceably fastened in a seat on the lateral surface of the rotor drum  11 , which is described in more detail under  FIG. 5 . As is indicated by the arrow  45 , the rotor  9  can be operated in both directions of rotation. 
     The bottom circumferential section of the rotor  9  is surrounded by a screen path, which in the present example is composed of four screen elements  13 . Each screen element  13  consists essentially of a screen support  14  upon which a perforated screen  15  is mounted. In cross-section, two screen elements  13  extend over nearly one quarter of the rotor circumference in mirror image ( FIG. 1 ); in the longitudinal direction, two screen elements  13  follow one another axially ( FIG. 2 ). 
     For pivoting support of the screen elements  13 , journal bearings  17  in which the screen carriers  14  are rotatably supported are located on the inner side of the transverse wall  1  and on both sides of a partition  16 . With the aid of the piston/cylinder units on the outside of the transverse walls  1 , whose movable pistons act on the screen supports  14  via working levers, the screen elements  13  can each be pivoted down. With open doors  5 , access to the perforated screens  15  and the rotor  9  is thus ensured. 
     The top longitudinal spars  3  each serve the purpose of stationary mounting of an axially parallel stator device, with a stator tool holder  19 , which extends across the entire axial distance of the two transverse walls  1 . The top of the stator tool holder  19  is inclined towards the rotor  9  and forms a support surface for platelike stator tools  21 , which are clamped against the stator tool holder  19  with the aid of clamping plates  22  and clamping screws  23 . In the region of the outer longitudinal sides of the stator tool holder  19 , adjusting screws  24  are also visible, with which radial adjustment or readjustment of the stator tools  21  can be undertaken in order to ensure the required working gap between the tool units  12  of the rotor  9  and the stator device. The rotor  9  and the stator device thus have an essentially symmetrical structure with respect to the vertical plane through the axis of rotation. 
     The feed material is supplied through a vertical feed shaft  25 , whose longitudinal walls  26  attach directly to the stator device in the vertical direction. In the region of attachment to the stator devices, the longitudinal walls  26  each have an opening  27  that extends from one transverse wall  1  to the opposing transverse wall. The transverse walls of the feed shaft  25  are reinforced as compared to the transverse walls  1  of the machine base frame, and continue upward beyond the rotor  9 . 
     Each opening  27  is closed by a flap  28 , which is mounted in a pivoting manner in the transverse walls  1  in similar fashion to the screen elements  13 . The pivot axes  29  of the flaps  28  are located in the region of the upper longitudinal edge of a flap  28 , where axial bearing journals are provided for this purpose. To protect the joint gap between a movable flap  28  and the rigid region of the feed shaft  25  that continues upward, each of the longitudinal walls  26  has a strip-shaped skirt  30  along its lower edge on the inside, which overlaps the top longitudinal edge of the flap  28 . Extending over the entire length of the flaps  28 , on their rear side facing away from the rotor  9 , is a deflector plate  33 , which is inclined towards its free edge in order to prevent material from collecting in the pivot region of the flaps  28 . 
     The flaps  28  are driven in a similar manner to the screen elements  13 , with the aid of piston/cylinder units that are not shown, whose cylinders on the outside of the transverse walls of the feed shaft  25  are attached in a stationary manner to the transverse walls, while their movable actuating pistons are each coupled to a lever seated in a rotationally fixed manner on the bearing journal of the flaps  28 . The pivoting motion of the flaps  28  is produced by extending the piston/cylinder units. 
       FIG. 3 through 6  show the detailed construction of a tool unit  12  and its attachment to the rotor  9 . The tool unit  12  comprises a tool holder  34 , which is composed of a first carrier section  31  and a second carrier section  32 , which are identical in construction. Each carrier section  31 ,  32  has an approximately cuboid shape with a flat underside  35  and flat faces  36 , with its edges being chamfered. The front side  37  of the tool carrier section  31 ,  32  essentially serves to accommodate any desired number of tools, which in the present example consist of four platelike cutter heads  38  with a square outline arranged next to one another. Each cutter head  38  is oriented such that one of its diagonals is parallel to the direction of the longitudinal extent of the carrier sections  31 ,  32 , and the other diagonal is perpendicular thereto. In this design, two adjacent cutter heads  38  touch in the region of their opposing points, which is explained in more detail under  FIG. 6 . This arrangement of the cutter heads  38  results in a zigzag shape of the active edge  41  of the tool unit  12  for the comminution. 
     The top sides of the carrier sections  31 ,  32  follow the course of the active edge  41  with a certain edge spacing, resulting in a slight radial projection of the cutter heads  38  above the carrier sections  31 ,  32 . 
     For secure attachment to the carrier sections  31 ,  32 , the cutter heads  38  are arranged in seats  39  on the front side  37  of the carriers  31 ,  32 . Each of the seats  39  is composed of a bearing surface  40  offset towards the rear side  42  of the carrier sections  31 ,  32 . As a result of the offset perpendicular to the bearing surface  40 , strip-shaped support surfaces  43  are produced, which accommodate two adjacent sides of a cutter head  38  in a positive-locking manner. The transition between the two support surfaces  43  here is composed of an outward rounding  44 . The bearing surfaces  40  each have a central through-hole  46  for passage of a mounting screw  47  ( FIG. 5 ). In order to illustrate this circumstance, the cutter head  38  on the left-hand side in the plane of the drawing is not shown in  FIG. 3 . 
     The rear side  42  of the carrier sections  31 ,  32  is designed to be essentially flat. However, in the region where the through-holes  46  emerge, local indentations  48  are provided in which the ends of the mounting screws  47  are anchored with the aid of nuts  49  that are screwed on. Beneath the indentations  48 , approximately halfway to the underside  35  of the carrier sections  31 ,  32 , a keyway  50  that runs parallel to the underside  35  can be seen that is intended to accommodate a feather key  51  in a positive-locking manner. 
     As is especially clear from  FIG. 3  and  FIG. 5 , for the purpose of obtaining a tool unit  12  according to the invention and preparing it for installation in a rotor  9 , two carrier sections  31 ,  32  are placed one on the other so their rear sides  42  are congruent. In the common contact plane  52 , the feather key is responsible for centering the first carrier section  31  relative to the second carrier section  32 . A tool unit  12  that has been prepared in this way is inserted in a seat on the rotor  9 , where it is secured solely through clamping with the aid of a radially clamped clamping wedge  53 , which exerts on the tool unit  12  a clamping force that is directed tangentially with respect to the axis of rotation. To this end, an inclined side surface of the clamping wedge  53  works together with a wall surface of a tool seat that likewise is inclined ( FIG. 5 ). 
       FIG. 6  shows the contact region between two rectangular or square processing tools—in the form of cutter heads  38 —located next to one another on a carrier section  31 ,  32 . The opposing peaks have, at their end regions, truncations  54  that permit full-area contact of the processing tools in the region of the truncations  54 . This has the advantage that the active edge  41  composed of the aggregate of the processing tools is preserved as a whole even after initial manifestations of wear have appeared. A size for the truncations  54  that is advantageous for this purpose arises when the diagonal spacing of the truncations is approximately 0.9 times to 0.95 times the spacing of the two other points without truncations. 
     The invention is not restricted to the present exemplary embodiment, but instead also encompasses embodiments in which a tool extends as a single part over an entire carrier section. In like manner, embodiments are possible in which the active edge formed by the tools has a different shape than a zigzag, for example is straight or wavy. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.