Abstract:
A refiner for shredding pulps having refining surfaces provided on a rotor and a stator and which form a cylindrical or a conical refining gap. The refining gap is set by wedges which are mounted on the stator and rotor and can be moved against each other.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to refining apparatus. More particularly, the present invention relates to apparatus for shredding pulps.  
           [0002]    Nowadays most of the refiners built are of twin disc design. The disadvantages of the twin disc refiner are the changing relative speed along the length of the refining zone, a relatively high idle running rating and problems with centering the rotor, particularly at low throughputs. Conical refiners are also used, whose most significant disadvantages are the poor pumping effect. This leads to throughput difficulties and, as a result, the need to enlarge the grooves in the refining zones, which reduces the edge length. The relative displacement of the knives when being set in relation to one another, the need for a sturdy design as a result of the bearing forces occurring, and the difficulties in changing the refiner plates can be considered further disadvantages.  
           [0003]    Another type of refiner known is the so called cylindrical refiner, as described in U.S. Pat. No. 5,813,618, for example. With this type of refiner, some of the disadvantages mentioned can be avoided, however it is important to ensure that the knives are set evenly in order to guarantee the same gap and thus, the same refining conditions over the entire circumference and along the lengths of the axial refining zones.  
         SUMMARY OF THE INVENTION  
         [0004]    The refiner according to the invention is thus characterized by the refining gap being set by wedges which are mounted on the stator and rotor and can be moved against each other. This causes an axial movement, of the same dimension over the entire circumference, to be converted into a corresponding radial movement. This principle guarantees that the knives have exactly the same setting.  
           [0005]    An advantageous further development of the invention is characterized by an axially movable wedge carrier being provided.  
           [0006]    A favorable further development of the invention is characterized by a radially movable wedge carrier being provided. This wedge carrier permits the corresponding axial movement to be converted into a radial movement, thus allowing the refining gap to be set exactly.  
           [0007]    A favorable configuration of the invention is characterized by the gap being continuously adjustable between 0 and 2 mm, preferably between 0 and 1 mm, for example between 0 and 0.5 mm. Thus the refining gap can always be set in an optimum way to suit the properties of the pulp suspension.  
           [0008]    An advantageous configuration of the invention is characterized by the gap being suitable for setting up to 15 mm. Thus, it is possible to avoid any damage to the refiner plates, also during start-up operations or if larger particles suddenly appear.  
           [0009]    A favorable further development of the invention is characterized by the relative speed at the periphery being 15-35 m/sec., preferably 20-30 m/sec.  
           [0010]    A favorable configuration of the invention is characterized by the rotor speed being between 400 and 1,800 rpm, preferably between 500 and 1,000 rpm.  
           [0011]    An advantageous further development of a refiner with twin rotor according to the invention is characterized by two wedges being provided at the axially movable wedge carrier and whose inclined surfaces slide over the corresponding surfaces of the radially adjustable wedge carrier.  
           [0012]    An advantageous configuration of the invention is characterized by the radially movable wedge carrier being divided into segments of a circle. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which:  
         [0014]    [0014]FIG. 1 is a schematic view of a first embodiment of the refiner of the invention;  
         [0015]    [0015]FIG. 2 is a schematic view of a second embodiment of the refiner of the invention;  
         [0016]    [0016]FIG. 3 is a schematic view of a third embodiment of the refiner of the invention;  
         [0017]    [0017]FIG. 4 is a schematic view of a fourth embodiment of the refiner of the invention;  
         [0018]    [0018]FIG. 5 is a schematic view of a fifth embodiment of the refiner of the invention;  
         [0019]    [0019]FIG. 6 is a schematic view of a sixth embodiment of the refiner of the invention;  
         [0020]    [0020]FIG. 7 is a schematic view of a seventh embodiment of the refiner of the invention;  
         [0021]    [0021]FIG. 8 is a schematic view of an eighth embodiment of the refiner of the invention;  
         [0022]    [0022]FIG. 9 a side view of the refiner of FIG. 1;  
         [0023]    [0023]FIG. 10 a cross section view of the rotor of FIG. 1;  
         [0024]    [0024]FIG. 11 is a schematic view of the refiner of the invention having a central stock discharge;  
         [0025]    [0025]FIG. 12 is a schematic view of the refiner of the invention having a central stock feed; and  
         [0026]    [0026]FIG. 13 is an alternate embodiment of the refiner of FIG. 12. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]    [0027]FIG. 1 shows a diagram of the setting mechanism at a refiner with a single cylinder. It comprises an axially movable wedge carrier  1  and a radially movable wedge carrier  2  on which a refiner plate  5  is mounted. The counter refiner plate  5 ′ is mounted on the rotor  4 . The energy from the setting mechanism is transferred along an inclined plane defined by the surface of the inclined face of wedge carrier  1  and the inclined face of wedge carrier  2  which are engaged at the inclined plane. If the wedge carrier  1  is now displaced axially, this results in radial displacement of the wedge carrier  2  due to the transfer of energy at the wedge. As a result, the gap  3  between the refiner plates  5  and  5 ′ can be set precisely.  
         [0028]    [0028]FIG. 2 shows an analogous variant, but the rotor  4  here is of conical design. As a result, the refiner plates  5  and  5 ′ are also designed as parts of a cone.  
         [0029]    [0029]FIG. 3 now shows a variant with a twin cylinder refiner.  
         [0030]    Here, too the axial displacement of the wedge carrier  1  exerts force on the wedge carrier  1  which is displaced in radial direction as a result. In this case, it also sets the gap  3  between the refiner plates  5  of the stator and the refiner plates  5 ′ of the rotor. The refining gap in operations is between 0 and 2 mm, for example 0.5 mm. If larger impurities occur or also in the start-up phase of the machine, the gap can be opened to up to 16 mm.  
         [0031]    [0031]FIG. 4 shows a further variant of the setting at a twin cylinder refiner. Instead of a single long wedge, there are two shorter wedge segments mounted on the wedge carrier  1 , each of which are approximately the same length as one of the cylindrical refining surfaces  5 ′. The wedge carrier  2  as counterpart beside these two cylindrical refining surfaces  5 ′ has inclined planes along which the wedge carrier  1  slides. It functions in the same way as in the preceding variants, where displacement of the wedge carrier  1  in axial direction in turn causes displacement of the wedge carrier  2  in radial direction. Since this movement is distributed between two wedge segment surfaces, this permits better and more even transfer of energy and thus, much more exact setting of the refining gap  3  between the refiner plates  5  and  5 ′.  
         [0032]    [0032]FIGS. 5 and 6 show analogous configurations, with a conical rotor narrowing from the center outwards in FIG. 5 and a conical rotor widening from the center outwards in FIG. 6.  
         [0033]    [0033]FIG. 7 shows a variant where the two wedge carriers converging on inclined planes are held together in the rotor. Here an axially movable wedge carrier  6  is provided that acts on a wedge carrier  7  which can be adjusted in radial direction and carries the refiner plates  9 ′ on the rotor. The stator  10  with the counter refiner plates  9  remains constant in this case, with the refining gap  8  being set between the refiner plates  9  and  9 ′.  
         [0034]    [0034]FIG. 8 shows another variant of the configuration according to FIG. 7, where the refiner plates  9  and  9 ′ form a conical refining gap  8 .  
         [0035]    [0035]FIG. 9 shows a view of a refiner according to the invention, where two sliding bolts  11  are shown, which help to move the wedge carrier  1  axially. The sliding bolts  11  are driven by a motor  13  from which the power is transferred by gears  12 . Due to these gears  12 , even adjustment of the sliding bolts  11  is also achieved. In addition, this illustration shows the feed  14  for the pulp suspension.  
         [0036]    [0036]FIG. 10 contains a possible section through a rotor. The illustration shows the axially movable wedge carrier  1 , the radially movable wedge carrier  2 , the refining gap  3  formed by the refiner plates  5  and  5 ′, and the rotor  4 . The radially movable wedge carrier  2  slides here along the inclined plane  15  between wedge carrier  1  and wedge carrier  2  and is displaced radially along the edges of the triangular mountings  16 .  
         [0037]    [0037]FIG. 11 shows a possible pulp feed variant to a twin cylinder refiner where the pulp is fed in through connections  14  and  14  and discharged again at the center through connection  18 . The pulp is deflected on both sides to the pulp feed channel by a disc  19  and further into the refining gap  3 . The same pulp routing is also possible with a twin cone which can be designed as a widening or a narrowing cone from the outer inlet to the center outlet.  
         [0038]    [0038]FIG. 12 shows a possible pulp feed variant to a twin cylinder refiner with the refining gap setting according to the invention where the pulp is fed in centrally through pulp feed  14  and discharged again at both ends of the refiner through the outlets  18  and  18 ′. This illustration shows the variant according to FIG. 4 however the variant according to FIG. 3 can also be used.  
         [0039]    [0039]FIG. 13 now shows a further variant using a combination of cylindrical and conical refining zones. The remaining elements correspond to those described under FIG. 12.  
         [0040]    While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.