Abstract:
A press for the mechanical dewatering of water-containing pulverised solid material is provided with a rotatable feed screw (3) which is so floatably mounted that it can perform a rotary pendular pivoting movement about a swivel point (D) lying in the area of the drive. Thereby, a high dewatering power is achieved with advantagous wear properties of the press. By special formation of the region where the solid material leaves the feed section (3), the effect and operating behavior can be further improved.

Description:
FIELD OF INVENTION 
     The invention relates to a dewatering press for compressibly dewaterable material comprising a rotatable feed screw, which is driven and mounted at the in-feed end and which is free from a physical mounting at the discharge end. The feed screw is disposed in a volume having an opening for the material in-feed through which the material (A) to be dewatered can reach the start region of the feed and dewatering section. The volume is partially bounded by a jacket provided with a multiplicity of openings, through which the water contained in the material which is to be dewatered can pass, while a substantial part of the material (A&#39;) present as solid matter is held back, this material being compacted and partially dewatered. The press further comprises a discharge located at one end of the feed section. 
     The operation of a dewatering press of this kind will be described in the following with reference to the example of waste obtained in the processing of used paper, but is also applicable to other compressibly dewaterable material. 
     TECHNICAL BACKGROUND 
     As is known, used or waste paper usually contains a certain proportion of unwanted stock or material which should be removed by processing for the purpose of the recycling of used paper. For this, a number of machines and processes are available to draw off as accepted stock the used paper, which is to be further processed, while the unwanted stock is removed therefrom as reject material. These reject materials are normally disposed of, or also, in special cases, reprocessed into new products. Since used paper processing normally takes place in aqueous suspension, the reject materials contain much water which makes them difficult to manipulate, and which considerably increases the transport and dumping costs for their disposal. 
     The mechanical separation of the water from the material by pressing has proved itself to be an economically viable and practical process. Consequently, for instance, worm presses are used in which a driven feed screw is arranged inside of a substantially concentric cylindrical or conical, perforated sheet metal jacket or the like. The reject material is fed in radially and is dewatered in cooperation with a dam apparatus, wherein the water can escape through the perforated sheet metal jacket or the like, whereas the reject materials are held back. The compression and dewatering of the reject can be improved when a conical form is chosen for the sheet metal jacket, the diameter of which reduces in the direction of movement of the reject material. Naturally, the outer worm diameter must also fit these geometrical dimensions. When the known dewatering worms are implemented as described, they are subject to a particularly large wear as a result of intensive rubbing between reject materials and the components of the machine. Namely, a considerable relative movement occurs under simultaneously enormous axial and radial forces between the already much thickened material and the components. Moreover, this reject material contains often many small metal particles and pieces of hard plastic, as well as fiber remnants which, as is known from practice, can lead to a high wear even of high quality metallic components. 
     PRINCIPAL OBJECT OF THE INVENTION 
     The object of the present invention is to form a dewatering press for compressibly dewaterable material in such a way that it is simply and clearly constructed, excessive wear at the machine parts is avoided, and simultaneously a high degree of dewatering is achievable. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The object is satisfied in a dewatering press of the initially named kind in that the feed screw is mounted at the in-feed end of the press so that the angle of its center line, which extends principally in the feed direction, can vary under the action of forces which act essentially perpendicular to the feed screw&#39;s axis line. 
     A special advantage of the subject of the invention lies therein that the feed screw, which is subject to particularly intensive demands, is not rigidly guided, but rather can adopt a freely adjustable position within a certain range, depending on the constitution and distribution of the material which is to be pressed. In this way, simple construction, good access at the discharge (cleaning) of the press as well as favorable wear properties, in particular for screw and sieve jackets, are combined with one another. As the feed screw is radially movable relative to the sieve jacket surrounding it, the treated material in between is especially well loosened up, which leads to a better dewatering. Such advantages can be further amplified by axial strips or the like which are often provided at the inside of the sieve jacket. An excessive loading of the machine parts is reliably avoided due to the possibility of deviation or angular yielding. In additional, a particularly good and homogenous dewatering can be achieved as an even pressure distribution is possible in the area of the jacket provided with an opening. 
    
    
     LISTING OF FIGURES 
     The invention will now be described in more detail with the aid of drawings. These show: 
     FIG. 1 a schematic cross-section of a dewatering press in accordance with the invention 
     FIG. 2 a plan view of the apparatus shown in FIG. 1 
     FIG. 3 a schematic of the subject of the invention with pivoted screw 
     FIG. 4 a schematic of a further advantageous embodiment, 
     FIG. 5 indicating three different screw positions, 
     FIG. 6 partial section of a variant for securing of the sieve jacket, 
     FIG. 7 a block diagram illustrating the operation of a special form of the dewatering press of the invention, 
     FIG. 8 a view of a special dewatering press as seen from above, 
     FIG. 9 a view of a discharge arrangement at the outlet of the dewatering press, and 
     FIG. 10 a simplified representation of an opened discharge arrangement at the outlet of the dewatering press. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 shows an embodiment of a dewatering press in accordance with the invention. The material A passes through an opening 1 into the volume 2, in which the feed screw 3 with its helix 3&#39; is present. The volume 2 is bounded by a mantle 4 which is perforated with holes 5, and which is, in this case, cylindrically constructed. The material is already dewatered, in passing through the feed section 6, not only by gravity, but also by compression which may occur during transportation. The water W runs into a dewatering container 8 via the openings 5 of the jacket 4. After having passed through the feed section 6, the material reaches the region of the discharge 9. A further compression can take place in a press section 7 connected hereto. In the case shown here, movable plates 10, 11 are placed against the material A&#39;. Further water W&#39; then passes into the dewatering container 8 as a result of the pressing. 
     The feed screw 3 is driven by drive unit 12 which, as is schematically shown, sets the shaft of the feed screw in rotation via a belt or the like. It is also recognisable that the drive unit is, in its totality, so mounted that it can participate in the rotary pendular pivoting movement of the feed screw 3. 
     The representation in FIG. 1 shows an example of how the mounting at the drive side end of the feed screw 3 can be effected. The bearings 16 and 17 shown can take up both the axial forces and the radial forces at this point, wherein, however, the possibility of the screw axis performing a rotary pendular movement is retained. The drive unit 12 is essentially carried by the described journalling, since it is connected with the drive side end of the feed screw 3. The torque originating from the drive force is transmitted to the housing 15 via the torque stay 13. With an appropriate construction of the machine, the lever moments at the bearings 16,17 originating from the gravity forces of the feed screw 3 and the drive unit 12 can be substantially balanced. 
     Even though apparatuses with horizontally lying feed and press sections have been shown, vertically or inclined arrangements are also directly conceivable, and under some conditions even advantageous. 
     The same press apparatus is shown in FIG. 2 as a view from above represented with a view onto the housing 15 and the in-flow opening 1. 
     In FIG. 3, in a sectional side view which has been somewhat exaggerated for clarity, the pivoting movement of the feed screw 3 together with the drive unit 12 is shown. The pivotal point D for this rotary pendular movement lies, as viewed axially, in the region of the bearing arrangement for the screw. 
     FIG. 4 shows a schematic view of the subject of the invention, wherein the viewing direction was chosen axially from outside onto the exit region of the press. The feed screw 3 with the helix 3&#39; and the outer surface 3&#34; can be recognised. In this embodiment the sieve jacket 4 is shown secured to the machine frame 20 at the points 21, while a large part of the circumference of the sieve jacket is held by yokes 18, which are radially disposed opposite to one another and which themselves have a mobility, albeit limited, perpendicular to the screw axis relative to the machine frame 20. They are connected with one another by connecting elements 19. Going still further, the sieve jacket 4 can be secured so that it is only held on its end face, being otherwise movable at its longitudinal side relative to the machine frame 20 (FIG. 6). Advantageously, the sieve jacket 4 can be made out of two half cylinders which are pressed together by the yokes 18. 
     Furthermore, the representation of FIG. 4 shows a number of strips 22, axially secured on the inside of the sieve which serve to prevent the revolution of the material to be fed and, moreover, to protect the surface of the sieve from wear. The strips can extend exactly radially or also inclined. Their effect is also advantageous for the dewatering function of the machine, as a processing of the material between the helix 3&#39;, in particular its outer surfaces 3&#34;, and the said strips 22 can take place as result of the rotary pendular movement of the feed screw 3. 
     Different positions of the pendularly rotating variable position feed screw 3 are shown in FIG. 5, enlarged and highly schematically and in the same viewing direction as FIG. 4, wherein various positions of the screw are shown by the different dotted lines. The transmission openings in the sieve jacket 4 are not shown here. 
     FIG. 7 shows in one diagram the individual functions which can be achieved by a special form of the apparatus in accordance with the invention. Used paper material S is processed in the processing 25, wherein waste is obtained, while the processed material S&#39;, which has been at least partially purified, is fed on. The waste, in the form of the material A which is to be dewatered, reaches a feed 26 comprising a feed and dewatering section 6. As a result of gravity and usually also by compression, water W is removed from the waste. The material A&#39; dewatered in this way is finally subject to press processing 27 in the press section 7, and under the release of further water W&#39; still more strongly dewatered and fed out as cork-like material A&#34;. 
     FIG. 8 shows a special pressing apparatus represented in view from above, with a view onto the housing 15. The material A passes through an opening 1 into the press and is processed as already described. After having passed through the feed and dewatering section 6, it reaches the region of the discharge 12. In the press section 6 now connected thereto, the pressing elements 23 and 24 come into operation. In the case shown here, they are movable in guide ways 28 perpendicular to the feed direction of the transportation screw and are periodically pressed against the material A&#39; by positioning motors, in particular servomotors 29. The servomotor, which is for instance hydraulically actuated, is supplied via stub pipes 30 with a pressure fluid. As a result of the pressing, further water W&#39; reaches the dewatering container 8. Naturally, other devices for the production of pressing force are also conceivable. The now heavily dewatered material A&#34; can fall out of the apparatus or is driven out by the material following it. The transportation screw is driven by a drive motor 12 which, as schematically indicated, sets the shaft of the transport screw in rotation via a belt or the like. 
     FIG. 9 schematically represents another possibility, namely how the pressing elements 23&#39; and 24&#39; can be pivotably mounted on the housing 15 via hinges 33 and can be moved by servomotors 29&#39;. The open position is shown thinner than the pressing position. 
     FIG. 10 shows in a simplified representation a pivotally opened discharge device in view from above. The discharge device contains a frame 31 which is openably and closeably secured to parts of the housing 15 of the dewatering press by hinges 32. This frame 31 carries hinges 33&#39; which serve for securing of the pressing elements 23&#34;, 24&#34; which have been drawn in a simplified fashion, so that these can move relative to the frame 31. 
     If the discharge device is swung downwardly when the dewatering press is not in use, the end of the feed screw 3 is relatively easily accessible, while the cork or plug A&#39; can stay in the up-pivoted discharge device. The discharge device can be once more swung into position in front of the feed screw, for instance after the completion of servicing of the dewatering press, and the operation of the dewatering screw once more initiated. As the cork A&#39; is once more at its old position, the optimum operating condition of the dewatering press is relatively quickly achieved.