WO2017081365A1

WO2017081365A1 - Disc screen, and material entanglement prevention means to be installed in disc screen

Info

Publication number: WO2017081365A1
Application number: PCT/FI2016/050786
Authority: WO
Inventors: Yrjö Romppainen
Original assignee: Bmh Technology Oy
Priority date: 2015-11-10
Filing date: 2016-11-07
Publication date: 2017-05-18
Also published as: EP3374097A1; EP3374097A4; FI126489B; FI20155821A

Abstract

The invention relates to a disc screen for dividing a flow of material into several particle sizes, the disc screen comprising a body (1); a plurality of parallel axles (2) spaced apart from one another and arranged rotatably in the body (1); an actuator (3) for rotating the axles; a plurality of screen discs (4) spaced apart from one another and arranged fixedly on the axles (2), the screen discs (4) of one axle (2) being axially offset with respect to the screen discs of an adjacent axle; a plurality of material entanglement prevention means (5) arranged between the screen discs (4); the entanglement prevention means (5) comprising an inner sleeve (6) placed on the axle (2) non-rotatably with respect thereto; an outer sleeve arrangement (7) freely rotatably arranged on the inner sleeve (6); and a stabilization arrangement (8) arranged in the outer sleeve arrangement (7) for preventing the outer sleeve arrangement (7) from rotating along with the axle (2) and the inner sleeve (6), the stabilization arrangement comprising a weight (8) arranged in a selected sector on an outer surface of the outer sleeve arrangement (7). The invention separately also relates to this entanglement prevention means.

Description

Disc screen, and material entanglement prevention means to be installed in disc screen

Background of the invention

[0001] The invention relates to a disc screen for dividing a flow of material into several particle sizes, the disc screen comprising a body; a plurality of parallel axles spaced apart from one another and rotatably arranged in the body; an actuator for rotating said rotatable axles about their longitudinal axis; a plurality of screen discs spaced apart from one another and arranged fixedly on said axles, the screen discs of one axle being axially offset with respect to the screen discs of an adjacent axle; a plurality of material entanglement prevention means arranged between the screen discs; the entanglement prevention means comprising an inner sleeve placed on the axle non-rotatably with respect thereto; an outer sleeve arrangement freely rotatably arranged on the inner sleeve; and a stabilization arrangement arranged in the outer sleeve arrangement for preventing the outer sleeve arrangement from rotating along with the axle and the inner sleeve. The invention separately also relates to this material entanglement prevention means.

[0002] A disc screen is probably the most widely used screen type for dividing a flow of material into two or more particle sizes. Several different variations of a disc screen are known. The most common ones include screens equipped with fixed steel discs. Depending on the material to be screened, the shape of the screen discs may vary significantly. Typical shapes have three to seven corners such that a side between the corners may be straight, curved or even concave. Another large device group is that of disc screens whose discs are differently shaped stars made of a flexible material and provided with different numbers of points.

[0003] Screens equipped with fixed steel discs are usually used for materials which do not contain hard particles, such as rocks or metal. Typically, such materials to be screened are, inter alia, chips and peat. Finger discs (stars) made of flexible materials are applied where the screen is very likely to be stuck. Such materials are, inter alia, building demolition waste, recycled fuels, vegetables, etc.

[0004] It is common to screen discs that the screen is formed by several successive axles that rotate in the same direction, and that the axle of the screen is provided with the aforementioned discs attached thereto equally spaced, and the particle size passing through the screen is determined by the axial distance between a disc on the axle and a disc on the next axle. Solutions are also known wherein the same screen is provided with axles equipped with differently spaced apart discs.

[0005] Even though it is possible by means of such stars made of a flexible material to prevent hard particles from being stuck between the discs, a problem yet to be solved is entanglement of a strip-like material around the axles of the screen. Such entanglement requires for the discs of the axle of the screen to be sufficiently widely spaced apart so as to leave enough space for the material with the entanglement property to wind around the sleeve between the screen discs. In other words, the screen is a so-called rough screen, in which case the distance between the screen discs is typically 20 mm or more. Such a strip-like material can be found, inter alia, among building demolition waste, such as belts, electric lines, and so forth, as well as in connection with recycled fuels, such as video tapes, cloths, etc. There are two basic principles for keeping the sleeves between the discs of the axles of the screen clean. Either the space between the discs is to be kept clean by means of various cleansing elements, or the part between the discs is constructed to resist said susceptibility to entanglement.

[0006] Such known cleansing elements include, inter alia, hard scrapers that are disclosed in patents DE 10 2010 023 268 Al and DE 20 2012 005 012 and attached to the stars, and separate intermediate space cleansers known, inter alia, from patent EP 1 764 163 Bl. The first-mentioned methods are suitable for removing a material stuck in the intermediate spaces between the discs, but are ineffective against strip-like entanglements. A separate cleanser is an expensive and space-consuming solution, and not particularly efficient for removing entangled materials.

[0007] Structures known for preventing a material from being entangled in a space between discs include, inter alia, a solution disclosed in patent EP 1 106 264 Bl wherein a loosely moving sleeve with a diameter that is considerably larger than that of the axle is placed between the discs. This, however, is in practice found to become easily stuck and, consequently, unable to prevent entanglement. A version more sophisticated than the previous one is disclosed in patent US 2012/0325729 Al, wherein a tubular sleeve is placed on an angular drive shaft and, on it, a double sleeve fixedly attached to one another. Between the double sleeve is provided a weight to keep the top sleeve in a determined position. The sleeves of the double sleeve may be either concentric or eccentric. The problem with the structure is that over time, as dirt and moisture get inside the structure, its operating characteristics deteriorate significantly. Further, the shape of the sleeve structure constitutes no natural obstacle to the entanglement of the material.

Summary of the invention

[0008] An object of the invention is thus to develop the above- described disc screen and material entanglement prevention means so as to enable the aforementioned problems to be solved. This object is achieved by the disc screen and entanglement prevention means according to the invention, which are characterized in that the stabilization arrangement comprises a weight arranged in a selected sector on an outer surface of the outer sleeve arrangement.

[0009] A particularly advantageous implementation is one in which between the inner sleeve and the outer sleeve is arranged a bearing system, a rolling bearing system in particular.

[0010] Preferred embodiments of the invention are disclosed in the dependent claims.

[0011] The solution according to the invention avoids the aforementioned problems and enables entanglement of a strip-like material to be prevented or at least considerably reduced. This invention significantly reduces this entanglement problem and the related disadvantages.

List of figures

[0012] The invention is now described in closer detail by means of the preferred embodiments and with reference to the accompanying drawings, in which:

Figure 1 is a general perspective view showing a disc screen as a star screen application;

Figure 2 shows an entanglement prevention means placed between two screen discs;

Figure 3 shows, sectioned, the screen discs and entanglement prevention means of Figure 2;

Figure 4 shows, separately and sectioned, the entanglement prevention means seen in Figures 2 and 3;

Figure 5 shows some alternative weights for an entanglement prevention means; and

Figure 6 shows removal of a material wound around the entanglement prevention means. Detailed description of the invention

[0013] Referring first to Figure 1, a disc screen for dividing a flow of material into several particle sizes, and to which the present invention may be applied, comprises a body 1; a plurality of parallel axles 2 spaced apart from one another in the same plane and rotatably arranged in the body 1; an actuator 3 for rotating the rotatable axles 2 about their longitudinal axis; and a plurality of screen discs 4 spaced preferably equally apart from one another and arranged fixedly on the axles 2. In such a case, the screen discs 4 of one axle 2 are axially offset with respect to the screen discs 4 of an adjacent axle 2. Further, the screen discs 4 of one axle 2 typically extend between the screen discs 4 of the adjacent axle 2, in which case the axial and radial distances of the screen discs 4 from one another provide dimensions for the largest particle size passing the screen. In this example, the screen discs 4 are star-shaped and thus comprise radially protruding points 4a. In an embodiment according to the invention, the screen discs 4 may, however, be of any type set forth in the above-described prior art wherein the shape of the outer circumference varies according to use and need.

[0014] Referring next to Figures 2 to 6, the disc screen in question also comprises an entanglement prevention means 5 preferably arranged in each screen disc intermediate space and comprising an inner sleeve 6 non-rotatably placed on the axle 2 having a polygonal cross section by means of a corresponding polygonal central hole 6a of the inner sleeve 6 (like the screen discs 4 themselves); an outer sleeve arrangement 7 freely rotatably arranged on the inner sleeve 6; and a stabilization arrangement 8 arranged in the outer sleeve arrangement 7 for preventing the outer sleeve arrangement 7 from rotating along with the axle 2 and the inner sleeve 6. The non-rotability of the inner sleeve 6 with respect to the axle 2 may, of course, be also implemented in many ways other than that described above, for instance by wedges or even by gluing.

[0015] The length of the inner sleeve 6 is selected such that its ends are pressed against hubs 4b of the screen discs 4. The axle 2 and the screen discs 4 attached thereto and the inner sleeves 6 thus together form a rotating entity.

[0016] Between the inner sleeve 6 and the outer sleeve arrangement 7 is arranged a bearing system, preferably a rolling bearing system 9. The length of the outer sleeve arrangement 7, in turn, is then selected such that its ends do not extend to the sides of the screen discs 4, in which case the rotating motion of the entity formed by the axle 2, the screen discs 4 and the inner sleeve 6 is not transmitted to this outer sleeve arrangement 7 but it stays in place owing to the sensitive bearing system 9 and the stabilization arrangement 8.

[0017] It is essential for the stabilization arrangement 8 to be formed of a weight 8 arranged in a selected sector on an outer surface of the outer sleeve arrangement 7. The magnitude, dimensions and shape of the weight 8 may be selected as necessary. The appropriately selected dimensions and shapes enable the entanglement of a material to be reduced considerably. Since the weight 8 resides on the outer surface of the outer sleeve arrangement 7, the shaping of the weight 8 is only restricted by the free space available around it. If, however, entanglement of the material does occur, the advantageous shaping of the weight 8 enables a strip-like piece 11 in particular to be prevented from becoming closely pressed against the surface of the outer sleeve arrangement 7, making the piece easy to remove by scissoring, for instance (cf. Figure 6).

[0018] The outer sleeve arrangement 7 naturally tends to settle in its correct position on account of gravity and the flow of material being screened, i.e. such that the weight 8 always resides down. It is therefore advantageous that the weight 8 and the outer sleeve arrangement 7 residing at it are also provided with liquid discharge openings 10 via which liquid, water especially, that has possibly entered the space between the inner sleeve 6 and the outer sleeve arrangement 7 is allowed to be discharged therefrom.

[0019] The weight 8 may be a separate part or it may be integrated with the outer sleeve arrangement 7 into one piece. In addition, the weight 8 may be divided in several sectors on the surface of the outer sleeve arrangement 7. Different weight shapes are shown in Figure 5.

[0020] In the drawings, a bearing shaft of the bearing system 9 is coaxial with a central axis of the axle 2, but the bearing shaft of the bearing system 9 may also be offset from the central axis of the axle 2, i.e. eccentrically with respect to the central axis of the axle 2.

[0021] The present invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may, however, vary its details within the scope of the attached claims.

Claims

1. A disc screen for dividing a flow of material into several particle sizes, the disc screen comprising

a body (1),

a plurality of parallel axles (2) spaced apart from one another and ro- tatably arranged in the body (1),

an actuator (3) for rotating said rotatable axles (2) about their longitudinal axis,

a plurality of screen discs (4) spaced apart from one another and arranged fixedly on said axles (2), the screen discs (4) of one axle (2) being axially offset with respect to the screen discs (4) of an adjacent axle (2),

a plurality of material entanglement prevention means (5) arranged between the screen discs (4),

the entanglement prevention means (5) comprising an inner sleeve (6) placed on the axle (2) non-rotatably with respect thereto; an outer sleeve arrangement (7) freely rotatably arranged on the inner sleeve (6); and a stabilization arrangement (8) arranged in the outer sleeve arrangement (7) for preventing the outer sleeve arrangement (7) from rotating along with the axle (2) and the inner sleeve (6),

characterized in that the stabilization arrangement comprises a weight (8) arranged in a selected sector on an outer surface of the outer sleeve arrangement (7).

2. A disc screen as claimed in claim 1, characterized in that between the inner sleeve (6) and the outer sleeve arrangement (7) is arranged a bearing system (9).

3. A disc screen as claimed in claim 2, characterized in that the bearing system (9) is a rolling bearing system.

4. A disc screen as claimed in claim 2 or 3, characterized in that a bearing shaft of the bearing system (9) is coaxial with a central axis of the axle (2).

5. A disc screen as claimed in claim 2 or 3, characterized in that the bearing shaft of the bearing system is offset from the central axis of the axle.

6. A disc screen as claimed in any one of the preceding claims, characterized in that a weight (8) and the outer sleeve arrangement (7) residing at it are also provided with liquid discharge openings (10).

7. A disc screen as claimed in any one of the preceding claims, characterized in that the weight (8) and the outer sleeve arrangement (7) are separate pieces.

8. A disc screen as claimed in any one of claims 1 to 7, characterize d in that the weight and the outer sleeve arrangement are integrated into one piece.

9. A disc screen as claimed in any one of the preceding claims, characterized in that the weight is divided in several sectors on the surface of the outer sleeve arrangement.

10. A material entanglement prevention means (5) to be installed on an axle (2) of a disc screen, between screen discs (4), the entanglement prevention means (5) comprising an inner sleeve (6) arranged to be installed on the axle (2) of the disc screen non-rotatably with respect thereto; an outer sleeve arrangement (7) freely rotatably arranged on the inner sleeve (6); and a stabilization arrangement (8) arranged in the outer sleeve arrangement (7) for preventing the outer sleeve arrangement (7) from rotating along with the axle (2) and the inner sleeve (6),

11. An entanglement prevention means as claimed in claim 10, characterized in that between the inner sleeve (6) and the outer sleeve arrangement (7) is arranged a bearing system (9).

12. An entanglement prevention means as claimed in claim 11, characterized in that the bearing system (9) is a rolling bearing system.

13. An entanglement prevention means as claimed in claim 11 or 12, characterized in that a bearing shaft of the bearing system (9) is coaxial with a central axis of the axle (2).

14. An entanglement prevention means as claimed in claim 11 or 12, characterized in that the bearing shaft of the bearing system is offset from the central axis of the axle.

15. An entanglement prevention means as claimed in any one of claims 10 to 14, characterized in that a weight (8) and the outer sleeve arrangement (7) residing at it are also provided with liquid discharge openings (10).

16. An entanglement prevention means as claimed in any one of claims 10 to 15, characterized in that the weight (8) and the outer sleeve arrangement (7) are separate pieces.

17. An entanglement prevention means as claimed in any one of claims 10 to 15, characterized in that the weight and the outer sleeve arrangement are integrated into one piece.

18. An entanglement prevention means as claimed in any one of preceding claims 10 to 17, characterized in that the weight is divided in several sectors on the surface of the outer sleeve arrangement.