Abstract:
A reliable, inexpensive option for the plates that function as wear parts and are mounted on an inner face of a casting wall of a stator. To achieve this the plates are designed as cast parts and are fixed to the inner face of the casting wall from an exterior of the stator. The plates are fixed by fixing bolts, which are screwed into the plates through the casting wall from the exterior. The plates have transverse threaded bores that correspond to the bolts. Respective spacer rings are pushed onto the fixing bolts secured by wedge-shaped cotters in both a positive and non-positive fit, and the wedge-shaped cotter pressing on the spacer rings that lie against the outer face of the casting wall. This invention is extremely economical and improves the operational safety in comparison to known options.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a stator for an impact crusher for separation of compound materials, with an outer face of the casing wall and an inner face of the casing wall, which is plated with a plurality of plates with ribs, wherein the plates are designed as wear parts and are attached replaceably. 
     2. Discussion of Related Art 
     Impact crushers are used in a variety of different technical fields, but herein only the use regarding the separation of compound materials is of interest. Such compound materials can be compounds of metal/metal, plastic/plastic, metal/plastic or mineral compounds with metals and/or plastics. Because the physical properties of the individual components of the compounds are different, such compound particles are separated in impact crushers and with each impulse different materials deform unequally elastically and unequally plastically and thereby separate. Typical compound materials, which are processed by the applicant are, for example, electronic waste and shredder waste of all kind, in particular from car recycling. 
     The use of impact crushers in this area is associated with enormous wear of the hammer tools as well as of the crusher walls. Accordingly the crusher walls, which are the inner casing wall of respective stators of such impact crushers, are plated with replaceable plates, which comprise ribs, on which particles of the compound materials to be delaminated impinge with high energy. As soon as the ribs are reduced to a certain minimum due to respective wear, the plates have to be replaced. Typically, such plates are made from steel plates and the ribs are formed by slotting machines or by milling. The back side of such plates are fitted to the actual casing wall of the stator. 
     From Great Britain Patent Reference GB-A-1397674 an impact crusher is known, the stator of which comprises a carrier plate on which a plurality of rib-shaped projections are welded, between which hammer tools are rotating pivotably supported on a rotor. The respective plate is attached to hydraulic-slide elements in order to adjust the plate according to the wear. After wearout of the projections, the entire adjustable base plate has to be replaced accordingly. This requires a relatively complex disassembly. 
     From PCT Patent Reference WO 00/53324 (BHS Sonthofen) another impact crusher is known, which represents the closest prior art. This stator of an impact mill serves for separation of compound materials and comprises an outer face of the casing wall as well as an inner face of the casing wall, which is plated with a plurality of plates with ribs, wherein the plates are designed as wear parts and are attached replaceably. This known solution intends to simply hook-in the plates tile-like at the upper edge of the stator casing wall. Accordingly, the plates have a continuous longitudinal rib with a hook-shaped cross section extending on the upper edge portion. This longitudinal rib engages in a ring groove formed on the stator wall. Along the periphery of the stator a plurality of such plates are hooked-in. The plates, which have a relatively high weight, are kept in position solely by gravity and are positioned abutting each other relatively tight. Normally, such plates are easy to replace but the mounting of these plates carries a potentially high risk. The peripheral speed in such impact crushers can be up to several hundreds km/h, which represents a high potential energy. If bigger parts get into the impact crusher, which accordingly are hard, because the shredder could not crush them, then these parts can be wedged in between the rotor and the stator. Although the hammer tools are typically supported pivotably, instantaneous acceleration forces occur, which can result in displacing of the plates or even in unhooking. After such an event a complete revision of the impact crusher is necessary. 
     SUMMARY OF THE INVENTION 
     It is one object of this invention to provide a stator of an impact crusher for separation of compound materials with a considerably higher safety, wherein at the same time the plates, which are wear parts, can be produced inexpensively. 
     This object can be achieved if the plates are metal cast plates having at least one transverse threaded bore and that the outer casing wall of the stator has passages, through which the fixing bolts with threads fitting into the threaded bore of the plates can be passed through and are visible from outside of the stator. 
     This unique mounting method is based on the consideration that inside the impact crusher an extremely high contamination occurs and thus a principally logical and easy screwing from inside is basically not realized. 
     The use of plates which are designed as metal cast plates is in particular inexpensive, but the precision of the cast results in an increase of the manufacturing cost. In order to be able to work with a decreased relative accuracy it is advantageous to provide the base of the plates with supporting strips projecting slightly from the base in order to qualify the supporting accuracy. 
     In order to achieve the required strength also with casted plates, such plates are provided advantageously with the features described in this specification and in the claims. 
     Further advantageous embodiments of the subject matter of this invention are discussed in this specification and in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings show a preferred embodiment of this invention, wherein: 
         FIG. 1  shows a stator of an impact crusher according to this invention, in a perspective view; 
         FIG. 2  shows a plate for encasement of an inner face of the casing wall with respective fasteners on its own, in a perspective view; 
         FIG. 3  shows a mat suitable for attachment between a plate and the inner wall face of the stator, in a plan view; 
         FIG. 4  shows the same mat but in a side view; 
         FIG. 5  shows a single plate on its own, in a perspective view; and 
         FIG. 6  shows the same plate together with the fasteners, in a perspective exploded view. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In  FIG. 1  a general view of the inventive stator of an impact crusher is shown. The stator is denoted in general with element reference numeral  1  and has a casing wall  2 , which has an inner face  3  of the casing wall  2  and an outer face  4  of the casing wall  2 . The upper edge of the casing wall  2  has a circumferential collar  5  for mounting of a cover which is not shown. The lower edge of the casing wall has a mounting flange  7 , with which the stator  1  can be mounted on a chassis, also not shown. The fixing bores  8  in the collar  5  serve for fixation of the mentioned cover, while the fixing bores  9  fix the casing wall  2  of the stator to the chassis. While the material to be delaminated is fed through the cover, which is not shown, into the impact crusher, the delaminated material exits through a material discharge opening  6  in the lower region of the casing wall  2 . In case the impact crusher works in a reverse flow mode, an air flow is blown in through the material discharge opening  6  at the same time. The entire inner face  3  of the casing wall is plated with plates  10 . This view shows that the plates  10  comprise crusher ribs  13  extending parallel to a center axis of the stator as well as reinforcement ribs  17 , which are not as high as the crusher ribs  13  and which are perpendicular to the crusher ribs  13 . With respect to the further design of the plates  10 , reference is made to the further description of the figures. 
       FIG. 2  shows the plate  10  and its fasteners in the assembled condition on its own in a perspective view. The plate  10  is also shown on its own in  FIG. 5 . The plate  10  comprises a lower base  11 , the thickness of which is relatively small with respect to the total thickness of the plate  10 . The plates  10  are wear parts and accordingly it is desirable that the usage volume is relatively high in relation to the total volume. This is achieved because the crusher ribs  13  in their height form a multiple of the thickness of the lower base  11 . The thickness of the base  11  need only be designed so that its strength is ensured. Also, the thickness of the base  11  is such that the fasteners are sufficiently stabilized in the plates  10 . In one design, reference is made to  FIG. 5 . 
     In order to design the base  11  optimally thin, reinforcement ribs  17  are provided perpendicular to the longitudinal direction of the crusher ribs  13 . The reinforcement ribs  17 , however, are considerably smaller in their height than the height of the crusher ribs  13 . The crusher ribs  13 , the upper end faces of which define a plane, which represents the work face  12 , have varying extending rib walls. Extending perpendicular to the lower base  11 , first rib walls  14  are shown and on the other side second rib walls  15  extend inclined to the base  11 . The first rib walls extending perpendicular to the base  11  are arranged in the mounted condition so that the particles of compound materials accelerated in the rotational direction impinge on the perpendicular faces  14 . The inclined second rib walls  15  form retaining walls, so to speak, which are not directly subject to wear. The accelerated particles, which are accelerated virtually tangential by the hammer tools at the rotor, virtually impinge only at the outer end of the first rib walls  14  extending perpendicular to the base  11 . Accordingly, the crusher ribs  13  are decreasing in their height due to the abrasion and it is not the crusher ribs  13  that become thinner and thinner, as could be expected. So that the working gap between the hammer tools at the rotor and the crusher ribs  13  at the stator stays within a small tolerance range, the efficiency of the impact crusher is maintained, and the hammer tools at the rotor are attached radially movable outwards. 
     The mounting of the plates  10  is achieved with the fixing bolts  20 . Normally, each plate  10  is attached with two fixing bolts. The fixing bolt is in principle cylindrical and only the end has an outside thread tapered in the region of the thread  21 , so that at the transition between the cylindrical portion of the fixing bolt  20  and the threaded portion  21  a shoulder  22  is formed. In the screwed-in condition, the shoulder  22  rests on the lower surface of base  11 . The fixing bolts  20  are inserted through the casing wall  2  of the stator  1 . Accordingly, along the entire periphery of the casing wall  2  respective bores are provided regularly. The fixing bolts  20  have a slotted hole  23  penetrating the bolt diametrically. This slotted hole  23  extending in the longitudinal axis of the fixing bolt  20  is dimensioned so that a respective wedge-shaped cotter  25  is insertable therethrough in a positive and non-positive fit. For each fixing bolt  20  there is an associated spacer ring  24 . The thickness of the spacer rings is selected in a manner that in a correctly mounted condition the wedge-shaped cotter  25  pushed through the slotted hole  23  is pressing on the spacer ring  24 . The obtained contact pressure prevents loosening of the fixing bolts  20 . So that the wedge-shaped cotter  25  cannot fall out of the slotted hole  23 , the wedge-shaped cotter  25  can be secured by a locking pin  29 . The locking pin  29  is pushed through a transverse hole  27  in the cotter. The locking pin  29  itself can, for example, be connected with the spacer ring  24 , which also has a transverse bore  26 , through a connection element  28 . Thus, the locking pin cannot get lost. The connection element  28  can be, for example, a wire or metal wire rope. 
     The transverse threaded bore  18  can virtually be seen only in the view according to  FIG. 1 . In  FIG. 6 , the two bores are only schematically drawn in a dashed line to indicate, where these transverse threaded bores  18  are located. 
     Between the base  11  of the plates  10  and the inner face  3  of the casing wall, mats  30  are placed. The mats  30  can, for example, be made of a vulcanized rubber. The mats  30  comprise on a central longitudinal axis as many holes  31  as fixing bolts  20  are penetrating the same. The size of the mats  30  can be equal to the length and width of the base  11  of a plate or to an integer multiple of the edge lengths of the plates  10 . In the illustrated example, the mat  30  in the  FIGS. 3 and 4  is designed corresponding to the width of a plate, and its length corresponds to the height of the casing wall  2  of the stator. Also within a stator, plates with different sizes can be used. However, the width of all plates is preferably designed identical, while their length is, for example, designed differently, so that as illustrated here, two or three rows on top of each other are sufficient. While plates with a large length are mounted with two fixing bolts  20 , plates with the half of the length are mounted to the casing wall  2  only with one single fixing bolt. The different plate lengths are required in order to obtain the necessary recess for the material discharge opening  6  without the need for special plates. 
     Preferably, the stator has an inner surface with a quadrangle cross section. This allows an at least approximately planar support of the plates  10 . The plates  10  made of steel cast have a planar base  11 . In addition, the plates  10  comprise supporting strips with a relatively small height at the base  11 . The formed supporting strips  16  may not be obligatory but they improve the support on the inner face  3  of the wall casing of the stator  1  because the same can exhibit casting unevenness. The linear support can be realized much simpler than a support with full contact. At the same time, in a preferred embodiment according to this invention, a mat  30 , as mentioned earlier, is placed between the inner face  3  of the casing wall and the base  11  of the plates. The mat not only serves as a compensation to obtain a fairly planar support but also effects at the same time a certain vibration dampening and thereby results in a reduction of sound emission. With the measures the vibrations are also reduced to the point that no loosening of the fixing bolts  20  takes place. 
     With the fixing bolts easily accessible from the exterior and their easy locking, the replacement of the plates on the inner face of the casing wall is possible with a considerably shorter downtime of the operation compared to options which provide a different mounting, while at the same time however the safety is very high. For replacement of the plates the cover, not shown here, is removed and thereafter the complete rotor is pulled out so that the plates are freely accessible. 
     The use of casted plates, which in principle are wear parts, is considerably less expensive than the previously used options, which are realized on machining centers in conventional mechanical engineering.