WO1996026017A1

WO1996026017A1 - A modular vibrating screen

Info

Publication number: WO1996026017A1
Application number: PCT/BR1996/000005
Authority: WO
Inventors: Andrzej Niklewski
Original assignee: Svedala Faço Ltda.
Priority date: 1995-02-24
Filing date: 1996-02-15
Publication date: 1996-08-29
Also published as: BR9500893A; AU4872496A

Abstract

A modular vibrating screen for separating large quantities of bulk material, comprising at least two longitudinally aligned modules (30), each module (30) integrally defining a portion of the longitudinal extension of the screen, each lateral wall (37) of each module (30) supporting a vibrator (20), whose actuation is individual, independent and self-synchronized with the opposite vibrator (20), the rotating shafts (21) of the eccentric masses (22) of each pair of vibrators (20) being mutually coplanar and disposed on vertical planes which are parallel to each other and to the longitudinal axis of the module, said shafts (21) being inclined in relation to said longitudinal axis of the respective screen module (30).

Description

A MODULAR VIBRATING SCREEN

Field of the Invention

The present invention refers, in general, to a new construction for modular vibrating screens for separating bulk materials and, more particularly, for large vibrating screens provided with linear oscillating motion. Background of the Invention In the known constructions, the linear oscillating motion of a vibrating screen with one or more overlying separating planes or decks is obtained by a pair of vibrators having eccentric rotating masses, always rotating in a synchronized way and in opposite directions, so that the forces generated towards the line that joins the centers of the vibrators are annulled, whereas in the direction perpendicular to this line said forces are summed, resulting in impulses that are always oriented in this direction, producing the linear motion of the screen body.

The mounting of the vibrators is conventionally carried out at the opposite sides of the screen body, so as to produce impulses oriented in an inclined direction, on a vertical plane, relative to the longitudinal shaft of the screen by an angle that varies according to the equipment design, usually around 60°.

In figure 1 of the attached drawings, there is schematically illustrated an elevational lateral view of a vibrating screen of linear oscillating motion, provided with a pair of vibrators 10, whose horizontal shafts 11 are orthogonal to the longitudinal shaft of the screen body, each vibrator comprising two eccentric masses 12, each positioned externally to one of the sides of the screen and interconnected by respective shafts, which are transversal to the screen body and supported on the latter through bearings 15, as shown in figure 2. In the condition illustrated in figure 1, the impulses of the synchronized eccentric forces occur according to the inclined directions represented by the parallel lines X.

In this prior art solution, the synchronization of the shafts 11 is assured by a gearing system. Nevertheless, as illustrated in figure 3, which is similar to figure 1, it has been more common to use the phenomenon, of self-synchronization of the masses 12 of the pair of vibrators 10, in order to eliminate the synchronizing gears 13. In the solution of figure 3, the vibrators further comprise horizontal shafts 11 transversal to the longitudinal shaft of the screen body, but said shafts are disposed away from the center of gravity M of the screen assembly. In this construction, the effect of self-synchronization of the eccentric masses generates a linear oscillating motion according to a direction y that passes by the center of gravity M of the screen assembly and by the median point of the distance between the shafts 11 of the vibrators. In the constructions of the transversal horizontal shaft illustrated in figures 1 and 3, the changes in the center of gravity M of the screen assembly caused by the distribution of the bulk material moving thereon modify the direction of the linear oscillating motion. As a result, these vibrators must have their horizontal shafts 11 mounted substantially spaced from the center of gravity of the screen assembly, in order to minimize the effects caused by the displacements of the center of gravity M along the direction of the linear oscillating motion. The above cited mounting characteristics of the vibrators with horizontal shaft transversal to the screen impair the stability of the assembly, besides requiring the provision of shafts transversely disposed along the screen body. With the aim to minimize or even eliminate the problems relating to stability and disposition of the shafts along the screen body, there have been proposed some constructions, in which on each side of the screen is affixed an independent vibrator 20, with its rotating shaft 21, which has one or more eccentric masses, parallely disposed to the longitudinal shaft of the screen but inclined on a vertical plane, in order to produce a linear oscillating motion according to a direction orthogonal to the rotating shaft of the vibrator and contained in the same vertical plane parallel to the screen shaft, such as schematically illustrated in figures 4 and 5. Each rotating shaft 21 is supported on a pair of bearings 25 mounted to the screen. This disposition of longitudinal inclined shafts allows the achievement of a higher operational stability in terms of direction and linear oscillation of the screen, as well as the self-synchronization of the eccentric masses of both vibrators, without requiring any mechanical connection therebetween, except the one provided by the structure of the screen body itself. The distribution of the material on the screen deck is in this case of little importance in the stability of the linear oscillating motion of the screen.

Despite the advantages mentioned above, the vibrators with longitudinal inclined shafts have serious limitations regarding their application in small screens, since the strong forces to be generated by the dimensioning of the eccentric masses, which are necessary to move the heavy screens, make difficult and complex the solution of the structural problems of the screen, as well as the construction and fixation of the vibrator itself. Disclosure of the Invention

Thus, it is an object of the present invention to provide a large modular vibrating screen, which is provided with linear motion produced by rotating eccentric masses which are arranged on both sides of the screen and independently actuated.

It is a more specific object of the present invention to provide a modular vibrating screen as described above, whose eccentric masses are actuated by respective lateral vibrators independently from each other and having shafts parallel to the longitudunal axis of the screen and inclined on a vertical plane. These and other objectives of the present invention are achieved by the provision of a modular vibrating screen comprising at least two longitudinally aligned modules, each module integrally defining a portion of the longitudinal extension of the screen, each lateral wall of each module supporting a vibrator, whose actuation is individual, independent and self- synchronized with the opposite vibrator, the rotating shafts of the eccentric masses of each pair of vibrators being mutually coplanar and disposed on vertical planes which are parallel to each other and to the longitudinal axis of the module, said shafts being inclined in relation to said longitudinal axis of the respective screen module.

The construction of the screen in modules allows to mount the equipment assembly, so that the latter can work with the production characteristics of the large equipments through vibrators presenting a stable operation in terms of oscillation, as well as a relatively small dimension, providing the consequent advantages relating to operation and assembly, since each pair of vibrators is dimensioned to produce the linear oscillating motion only of the respective screen module.

Brief Description of the Drawings

The invention will be described below, with reference to the attached drawings, in which:

Fig. 1 shows, schematically, an elevational lateral view of a vibrating screen of linear oscillating motion and known construction, which is provided with a pair of vibrators with horizontal shafts perpendicular to the longitudinal shaft of the screen,- Fig. 2 shows a schematic upper view of the known construction illustrated in figure 1;

Fig. 3 Fig. 1 shows, schematically, an elevational lateral view similar to that of figure 1, but illustrating a construction in which the shafts of both vibrators are located away from the center of gravity of the screen assembly;

Figures 4 and 5 Fig. 1 show, schematically and respectively, an elevational lateral view and an upper plan view of a vibrating screen of linear oscillating motion in another known construction, in which there is affixed, on each side of the screen, a vibrator with a shaft which is inclined but parallel to the longitudinal shaft of the screen,-

Fig. 6 shows a rather schematic perspective view of a modular vibrating screen constructed according with the present invention and which is formed by the longitudinal alignment of a plurality of screen modules; and

Fig. 7 illustrates a perspective view of one of the screen modules of the construction illustrated in the previous figure. Best Mode for Carrying Out the Invention Since the constructive characteristics of the prior art have already been discussed in the introduction of this disclosure and illustrated in figures 1 - 5, they will not be discussed again.

As illustrated in figures 6-7, the vibrating screen of the present invention consists of one or more longitudinally aligned modules 30, each module defining integrally only a portion of the minimum longitudinal extension that the screen must present in order to operate as a screening unit. In case the screening plant includes constructions with two or more screens disposed in series, the present invention allows all screens to be substituted by an equivalent number of longitudinally aligned screen modules, each module defining only a portion of the length of each individual screen of the conventional constructions, but having a width which is equal to that of the screen. In general, the length of each screen module 30 is smaller than its width. The width/length dimensional relation may even be smaller than the equipment in situations in which the whole dimensioning of the screen accepts, without any relevant structural and constructive problems, a reduced number of modules to form the screening equipment.

As illustrated, each module 30 may have multiple overlying separating decks 35, each separating deck 35 having a portion 36 of its extension forwardly projecting from one of the end edges of the module 30, so as to be projected beyond the opposite end edge of the module 30 immediately adjacent, allowing the non- screened material over the separating decks 35 of a module 30 to be discharged on the corresponding separating decks 35 of the module 30 disposed immediately downstream.

As already discussed regarding figures 4 and 5, each module lateral wall 37 supports a vibrator 20, whose actuation is individual, independent and self- synchronized with the vibrator mounted at the opposite lateral wall 37 of the module 30.

The rotating shafts 21 of the eccentric masses 22 of the pair of opposite vibrators 20 are coplanar to each other and disposed on vertical planes parallel to each other and to the longitudinal axis of the module 30, said shafts 21 being equally inclined relative to said longitudinal axis of the respective screen module 30. With the construction proposed herein, each screen module receives an actuation which is dimensioned in function of the mass of the individual module and not of the whole screen assembly, allowing the use of vibrators which are relatively small and individually subdimensioned in relation to the overall production rate of the screen.

Claims

1. A modular vibrating screen for separating large quantities of bulk material, characterized in that it comprises at least two longitudinally aligned modules (30) , each module (30) integrally defining a portion of the longitudinal extension of the screen, each lateral wall (37) of each module (30) supporting a vibrator (20) , whose actuation is individual, independent and self-synchronized with the opposite vibrator (20) , the rotating shafts (21) of the eccentric masses (22) of each pair of vibrators (20) being mutually coplanar and disposed on vertical planes which are parallel to each other and to the longitudinal axis of the module, said shafts (21) being inclined in relation to said longitudinal axis of the respective screen module (30) .

2. Screen, as in claim 1, characterized in that each module (30) has a length at maximum equal to the width of the screen.

3. Screen, as in claim 1, characterized in that each module (30) has at least one separating deck (35) , each presenting a portion (36) of its extension which occupies practically the whole width of the screen and which is forwardly projected from one of the end edges of the module (30) , in order to be projected beyond the the opposite end edge of the module (30) immediately adjacent.