CENTRIFUGAL SCREW, AND SOLID BOWL SCREW CENTRIFUGE

Abstract

The invention relates to a centrifugal screw (10) comprising a substantially tubular screw hub (15) and a screw flight (20), wherein at least some portions of a root (21) of the screw flight (20) are attached directly to the tubular screw hub (15). According to the invention, rods (30) are formed between at least two turn portions (25) in the longitudinal direction (R) of the centrifugal screw (10), said rods (30) being entirely or nearly entirely located at a distance from the screw hub (15).

Claims

1. A centrifugal screw (10) having an essentially tube-shaped screw hub (15) and a screw spiral (20), wherein a spiral basis (21) of the screw spiral (20) at least in sections is directly attached to the tube-shaped screw hub (15), characterized in that rods (30) are designed in the longitudinal direction (R) of the centrifugal screw (10) between at least two winding portions (25), wherein the rods (30) are designed to be spaced completely or almost completely from the screw hub (15).

2. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) extend across several winding portions (25, 25, 25).

3. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) are designed to be in parallel and/or similar to each other.

4. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) are guided through openings (28, 29) of the screw spiral (20), wherein the openings (28) preferably are circular and/or elliptical and/or cam-shaped and/or are designed as longitudinal recesses (29) starting from the spiral basis (21).

5. The centrifugal screw (10) according to claim 1, characterized in that the ratio (Dk/Da) of the diameter of the screw hub (Dk) to the outer diameter of the screw spiral (Da) is 0.6, in particular 0.5, particularly preferred 0.4.

6. The centrifugal screw (10) according to claim 1, characterized in that the ratio (Ds/Da) of the diameter of the circle (Ds), where the rods (30) are arranged, to the outer diameter of the screw spiral (Da) is 0.8, in particular 0.7, particularly preferred 0.6.

7. The centrifugal screw (10) according to claim 1, characterized in that the ratio (Dst/Da) of the diameter of one rod (Dst) to the outer diameter of the screw spiral (Da) is 0.15, in particular 0.1, particularly preferred 0.05.

8. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) extend essentially completely across a cylindrical longitudinal portion (11) of the centrifugal screw (10).

9. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) extend at least in sections starting from a/the cylindrical longitudinal portion (11) of the centrifugal screw (10) up to the portion (12) at the solid-discharging end of the centrifugal screw (10).

10. The centrifugal screw (10) according to claim 1, characterized in that metal sheets (60) are designed in sections between the screw hub (15) and individual rods (30) and/or rod portions (31).

11. The centrifugal screw (10) according to claim 10, characterized in that at least one of the metal sheets (60) has at least one metal sheet opening (61), preferably is designed to be perforated.

12. The centrifugal screw (10) according to claim 1, characterized in that the rods (30) are designed to be bent at least in sections, wherein the bent rods (30) preferably are positioned such in the longitudinal direction (R) of the centrifugal screw (10), that the bent rods (30) form a rod body (65), the largest outer diameter of which is designed in a middle segment (80) of the centrifugal screw (10).

13. The centrifugal screw (10) according to claim 12, characterized in that the rods (30) each are bent at several places such that several bending portions are formed.

14. The centrifugal screw (10) according to claim 1, characterized in that the screw hub (15) is designed as a slotted screw hub or as a tube screw hub.

15. A solid bowl screw centrifuge comprising a centrifugal screw (10) located within a drum, wherein the centrifugal screw (10) is designed according to claim 1.

Description

[0079] Shown are in:

[0080] FIG. 1 a perspective view of a centrifugal screw according to the invention according to a first exemplary embodiment;

[0081] FIG. 2 a longitudinal sectional view through a centrifugal screw according to the invention according to a further exemplary embodiment according to the invention; and

[0082] FIGS. 3-6 further embodiments according to the invention of a centrifugal screw according to the invention in a perspective representation or in a side view.

[0083] In the following, the same reference numerals will be used for equal parts or parts of equal action.

[0084] FIG. 1 shows the principal construction of a centrifugal screw 10 according to the invention. The representation is a perspective representation.

[0085] The centrifugal screw 10 has a screw hub 15 and a screw spiral 20. The screw hub 15 essentially is designed to be tube-shaped. Into the tube-shaped base structure of the screw hub 15, individual openings 16 are introduced.

[0086] Furthermore, the inflow area 17 of the screw hub 15 is represented. In the inflow area 17, several rectangular openings are designed. In the represented example, it is a so-called bushing screw. That means that wear bushings can be introduced into the openings of the inflow area 17. These wear bushings can correspondingly be exchanged and renewed.

[0087] The centrifugal screw 10 can essentially be divided into two portions. In this case, there is a cylindrical longitudinal portion 11 and a portion 12 at the solid-discharge end. In the cylindrical longitudinal portion 11, the screw hub 15 essentially has a cylindrical shape. The portion 12 at the solid-discharge end has to be understood as being such a functional portion that serves in particular for the transport into the direction of the solid-discharge of the solid matter separated from the material to be processed.

[0088] The cylindrical longitudinal portion 11 is designed in the longitudinal direction R as the first portion. The portion 12 at the solid-discharge end follows.

[0089] The longitudinal direction R essentially runs in parallel to the longitudinal axis L of the screw hub 15. The longitudinal direction R is defined in the represented example as being the direction of the transport of the solid discharge. The solid matter transport in the representation of FIGS. 1-6 each is performed from the right to the left side.

[0090] It can be recognized that the spiral basis 21 of the screw spiral 20 is directly attached to the tube-shaped screw hub 15 or directly to the outside 18 of the screw hub 15. In the represented example, the screw spiral 20 is directly connected to the outside 18 of the screw hub 15 across the complete longitudinal extension of the screw hub 15. Preferably, the screw spiral 20 and the screw hub 15 are welded together.

[0091] In the cylindrical longitudinal portion 11, the screw spiral 20 has a constant outer diameter. The outer diameter of the screw spiral 20 is designed at the spiral tip 22. In the portion 12 at the solid-discharge end, the screw spiral 20 is designed to be conically tapering. This means that the outer diameter of the screw spiral 20 decreases in the longitudinal direction R in the portion 12 at the solid-discharge end.

[0092] In the longitudinal direction R of the centrifugal screw, rods 30 are designed between at least two winding portions 25. The rods 30 are designed to be spaced from the screw hub 15.

[0093] As a winding portion 25, in each case a 360-winding of the screw spiral 20 has to be understood. In the represented example, the rods 30 extend from the first winding portion 25 to the last winding portion 25 of the cylindrical longitudinal portion 11.

[0094] The rods 30 are arranged to be evenly distributed in the circumferential direction. In the present case, eight rods 30 are designed. The rods 30 are guided through openings 28 of the screw spiral 20.

[0095] It would be furthermore possible for the rods 30 to consist of partial segments, i.e., of individual rod portions which are each attached individually between the winding portions 25. For this purpose, an attachment would be respectively made on the front side 23 of a first winding portion and on the rear side 24 of a further, i.e., subsequent winding portion 25.

[0096] In an arrangement of individual rod portions, the rods thus have not to be positioned in relation to the winding portions to be flush. An offset arrangement of the individual rods or rod portions could be made.

[0097] In the present example, the rods 30 have circular cross sections. The openings 28 of the screw spiral 20, for example, have the same geometry as the cross-sectional geometry of the rods 30.

[0098] In the present case, the openings 28 could be designed to be circular. In order to be able to position long individual rods 30 across several spiral portions 25, the openings 28 of the individual winding portions 25 need to be arranged to be flush to each other.

[0099] Further opening shapes, for example, may be elliptical or cam-shaped.

[0100] In the present example, the rods 30 essentially extend completely across the cylindrical longitudinal portion 11 of the centrifugal screw 10. As an essentially complete extension, such an extension has to be understood in the present case, which starts with the first winding portion 25 and ends with the last winding portion 25. In the area of the bearing reception 40, no rods 30 are arranged.

[0101] In other words, the rods 30 do not protrude up to the first frontal side 41 of the screw hub 15. The frontal side 41 is in the present case the frontal side 41 which comes first into to the longitudinal direction R. This first frontal side 41 is arranged to be opposite to the second frontal side 42 of the screw hub 15. The second frontal side 42, however, is to be understood to be a part or portion of the portion 12 at the solid-discharge end of the centrifugal screw 10.

[0102] In FIG. 2, a centrifugal screw 10 according to the invention is represented in a longitudinal cut representation. A constructional difference is with respect to the portion 12 at the solid-discharge end. This is constructed in the represented example having a double truncated cone shape.

[0103] The double truncated cone shape is formed by adjacent truncated cones 51 and 52. The first truncated cone 51 is arranged such relative to the second truncated cone 52 that the respective (imaginary) base surfaces of the truncated cones 51 and 52 are designed in the connecting portion to adjoin to each other. The rods 30 extend starting form the cylindrical longitudinal portion 11 of the centrifugal screw 10 up to the portion 12 at the solid-discharge end. In particular, the rods 30 extend almost up to the connecting portion 53.

[0104] Furthermore, different diameter specifications may be recognized. The ratio (Dk/Da) of the diameter of the screw hub Dk up to the outer diameter of the screw spiral Da preferably is 0.6, in particular 0.5, particularly preferred 0.4.

[0105] The ratio (Ds/Da) of the diameter of the (imaginary) circle Ds, on which the rods 30 are arranged, to the outer diameter of the screw spiral Da preferably is 0.8, in particular 0.7, particularly preferred 0.6.

[0106] The ratio Dst/Da of a diameter of a rod Dst to the outer diameter of the screw spiral Da preferably is 0.15, in particular 0.1, particularly preferred 0.05.

[0107] The rods 30 are arranged to be in parallel to one another. In particular, the rods 30 are arranged to be in parallel to one another as well in parallel to the longitudinal axis L of the screw hub 15.

[0108] In FIG. 3, a special realization of the screw spiral 20 is represented. The screw spiral 20 is directly attached to the tube-shaped screw hub 15 or the outside 18 only at least in sections with the spiral base 21. The openings 29 of the screw spiral 20 are designed to be longitudinal recesses. The longitudinal recesses 29 are shaped such that the width of the recesses decreases starting from the spiral basis 21 in the direction of the spiral tip 22. This facilitates mounting and introducing the rods 30 into the openings 29. The rods 30 may be pushed out to the outside from the direction of the screw hub 15 in the direction of the spiral tip 22. The dimension of the most minimal width of the opening 29 is dimensioned such that the rods 30 can be attached to be clamping within the openings 29.

[0109] In FIG. 3 moreover, such an embodiment of a centrifugal screw 10 is represented, according to which the portion 12 at the solid-discharge end is designed in the shape of two truncated cones 51 and 52 adjoining each other. The rods 30 extend up to the area of the first truncated cone 51. The Figure shows the ends 33 of the rods 30 lying at the outside of the first truncated cone 51.

[0110] In FIG. 4, such an embodiment of a centrifugal screw 10 is represented which is further developed with respect to the embodiment shown in FIG. 3.

[0111] In the cylindrical longitudinal portion 11 of the centrifugal screw 10 metal sheets 60 are designed between the individual rod portions 31 and the screw hub 15 or the outside 18 of the screw hub 15.

[0112] A portion of the rod 30 has always to be understood to be a rod portion 31 designed between two winding portions 25. The metal sheet 60, for example, is welded to the rod portions 31 and the outside 18 of the screw hub 15.

[0113] The metal sheets 60 serve for further stabilizing the centrifugal screw 10. The metal sheets 60 are preferably arranged in such a portion of the cylindrical longitudinal portion 11 which is arranged in the proximity of the first frontal side 41.

[0114] Seen in the longitudinal direction R, the metal sheets 60 are preferably designed in a first third of the cylindrical longitudinal portion 11. It is possible for the metal sheets 60 to be designed in this first third, in particular in a first quarter, of the cylindrical longitudinal portion 11 between all of the rod portions 31 designed there and the screw hub 15.

[0115] As represented in FIG. 4, the metal sheets 60 have openings 61 forming an opening pattern. The openings 61, on the one hand, serve for reducing the weight of the metal sheets 60. Furthermore, the flow properties within the drum of a solid bowl screw centrifuge (not represented) are improved.

[0116] In FIG. 5, a centrifugal screw 10 is illustrated having portion 12 at the solid-discharge end that is simply designed. In the represented example, the portion 12 at the solid-discharge end essentially consists of a cone-shaped envelope surface.

[0117] In the cylindrical longitudinal portion 11, the rods 30 are bent at least in sections. In particular, the ends of the rods 30 pointing into the direction of the first frontal side 41 of the screw hub 15, are bent. The ends 33 of the rods 30 are not bent. The ends 33 are in the present example attached to a transverse disc 70. The rods 30 are arranged to be essentially spaced from the screw hub 15. Only the ends 32 of the rods 30 fit closely for being fixed to the screw hub 15. In FIG. 5, an embodiment of the invention is shown illustrating an almost complete spacing of the rods 30 from the screw hub 15.

[0118] In FIG. 6, a further embodiment with respect to bent rods 30 is represented. In the illustrated example, both the ends 32 of the rods 30, and the ends 33 of the rods 30 are designed to be fixed to the screw bub 15. Due to bending the rods 30 such that the ends 32 and 33 each are bent pointing into the direction of the screw hub 15, such a rod body 65 is formed, the largest outer diameter of which is designed in a middle segment 80 of the centrifugal screw 10.

[0119] Such a portion of the centrifugal screw 10 has to be understood to be a middle segment 80, that is designed to be spaced both from the first frontal side 41 and the second frontal side 42. The rod body 65 is not to be understood to be a continuous body. Rather, the structure of the bent rods 30 is arranged relative to one another such that a kind of body is formed.

[0120] The rod body 65 represented in FIG. 6 has a spindle-shape. The convexities are thus designed to be approximately central to the course of the rods from the ends 32 up to the ends 33.

[0121] It should be noted in conclusion that all of the features mentioned in the documents of application and in particular in the dependent claims, despite the formal back reference made to one or several certain claim/s, should receive an autonomous protection even singly or in any arbitrary combination.

LIST OF REFERENCE NUMERALS

[0122] 10 centrifugal screw [0123] 11 cylindrical longitudinal portion [0124] 12 portion at the solid-discharge end [0125] 15 screw hub [0126] 16 opening [0127] 17 inflow area [0128] 18 outside [0129] 20 screw spiral [0130] 21 spiral basis [0131] 22 spiral tip [0132] 23 front side [0133] 24 rear side [0134] 25, 25, 25 winding portion [0135] 28 opening [0136] 29 opening [0137] 30 rod [0138] 31 rod portion [0139] 32 end of the rod [0140] 33 end of the rod [0141] 40 bearing reception [0142] 41 first frontal side [0143] 42 second frontal side [0144] 51 first truncated cone [0145] 52 second truncated cone [0146] 53 connecting portion [0147] 60 metal sheet [0148] 61 opening [0149] 65 rod body [0150] 70 transverse disc [0151] 80 middle segment [0152] R longitudinal direction [0153] L longitudinal axis [0154] Da outer diameter of screw spiral [0155] Dk diameter of screw hub [0156] Ds diameter of circle of rods [0157] Dst diameter of one rod