Vibrating screen

Abstract

The vibrating screen have a screen deck, two sidewalls and a mechanical vibrator comprising two shafts, rotating at the same rotation and in opposite directions, each one of the end portions of each shaft carrying an eccentric weight and being supported on bearings which are supported in the sidewalls of the vibrating screen. The shafts have their end portions, adjacent to each other, supported on bearings mounted to a same bearing case fixed to beams, transversal and having opposite ends fixed to the sidewalls of the vibrating screen. Each end portion of a shaft carries an eccentric weight with a total mass different from that one of the eccentric weights of the end portions of the other shaft, said shafts rotating in determined phases, defining the inclination of the major axis of an elliptical movement imparted to the screen deck.

Claims

1. A vibrating screen comprising: at least one screen deck defined between two screen deck sidewalls, the screen deck configured to support bulk material; a mechanical vibrator mounted to the screen deck sidewalls and having two transversal shafts which rotate at the same rotation speed and in opposite directions, each shaft having end portions, each end portion carrying at least one eccentric weight; at least two beams extending transversal to a longitudinal axis of the vibrating screen and each having opposite ends fixed to one of the screen deck sidewalls; wherein the end portions of the shafts are each supported by a plurality of bearings mounted to one of two bearing cases which are each removably fixed to the beams such that each of the end portions is adjacent to one of the end portions of the other one of the shafts, wherein each of the bearing cases includes a pair of opposite bearing sidewalls and wherein each of the eccentric weights is located externally to the bearing sidewalls; wherein a total mass of the at least one eccentric weight carried on each end portion of one of the shafts is different than a total mass of the at least one eccentric weight carried on each end portion of the other one of the shafts; and wherein said two shafts rotate in determined phases to impart elliptical movement to the screen deck, the major axis of the elliptical movement having a forward and upward inclination, to transport the bulk material along the screen deck.

2. The vibrating screen of claim 1, wherein the plurality of bearings supporting each end portion includes a pair of bearings with one bearing mounted to each of the opposite sidewalls.

3. The vibrating screen of claim 2, wherein the end portions of each of the shafts carries a gear, and each gear is engaged with the gear carried by the adjacent end portion of the other shaft; and wherein said gears are each housed in the interior of one of the bearing cases between the bearing sidewalls, each gear being housed between the pair of bearings supporting the respective one of the end portions that carries the gear.

4. The vibrating screen of claim 1, wherein the end portions of at least one of the two shafts are configured as drive shafts; and wherein the drive shafts are linked to each other by an intermediate portion of the shaft that extends between the drive shafts, the drive shafts being connected to the intermediate portion by respective flexible couplings.

5. The vibrating screen of claim 1, wherein the mechanical vibrator is mounted above the center of gravity of the vibrating screen and displaced in a longitudinal direction relative to the center of gravity of the vibrating screen, which balances the eccentric, longitudinal and transversal impulses on incoming and outgoing portions of the bulk material in relation to the screen deck.

6. The vibrating screen of claim 1, wherein the two bearing cases and the shafts are covered by a protective cowl removably fixed on the beams.

7. The vibrating screen of claim 1, wherein the bearing cases each include an opening on a top side of the bearing case.

8. The vibrating screen of claim 7, wherein the two bearing cases and the shafts are covered by a protective cowl removably fixed on the beams, wherein the protective cowl covers the openings of the bearing cases and includes a downward facing opening.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described with reference to the accompanying drawings, given by way of example of a possible embodiment of the invention and in which:

(2) FIG. 1 shows a simplified perspective view of a vibrating screen provided with two screen decks arranged between two sidewalls on which the mechanical vibrator of the invention is removably attached;

(3) FIG. 2 shows, schematically and simplified, a cross-sectional view of the vibrating screen and the mechanical vibrator shown in FIG. 1;

(4) FIG. 3 shows, schematically and in a side view, a vibrating screen with a mechanical vibrator according to the invention, provided with two transversal shafts rotating in opposite directions and at the same frequency, each of which carrying, in its end portions a pair of eccentric weights having a total mass different from that one of the eccentric weights of the other shaft, the eccentric weights being in a first position corresponding to the longitudinal and upward elliptical displacement of the screen deck;

(5) FIG. 3A schematically shows the eccentric weights of the two shafts in the same first upward longitudinal position shown in FIG. 3;

(6) FIGS. 3B, 3C and 3D schematically represent the eccentric weights of the two shafts, at positions representing the other three displacements, transversal upward, longitudinal downward and transversal downward respectively, of the screen deck of the vibrating screen, according to the two axes of the desired elliptical movement; and

(7) FIG. 4 schematically shows a top plan view of the vibrating screen shown in FIG. 3 and the two transversal shafts of the mechanical vibrator being connected to each other by gears.

DETAILED DISCLOSURE OF THE INVENTION

(8) As illustrated and already mentioned above, the invention relates generally to vibrating screens PV for sorting bulk material and, more specifically, to those screens of the type comprising at least one screen element 10, generally in the form of an elongated chute and substantially U-shaped profile and having a screen deck 11 onto which is moved a continuous load of bulk material such as various ores, the screen deck 11 being defined between two sidewalls 12 of the vibrating screen PV.

(9) As shown, the mechanical vibrator VM comprises a pair of shafts 20 transversal to the longitudinal axis of the vibrating screen 10, each having an end portion 20a carrying at least one eccentric weight 30.

(10) In the illustrated construction, the adjacent end portions 20a of the shafts 20 are rotatively supported on bearings 40 which are mounted in a same bearing case 50 which is removably fixed on beams 13, generally two and transversal to the longitudinal axis of the vibrating screen PV. The opposite ends of the beams 13 are fixed to the sidewalls 12 of the vibrating screen PV, generally on the inner face of said sidewalls.

(11) According to the illustrated construction, each bearing case 50 comprises a pair of opposed sidewalls 51, the end portions 20a adjacent to each other of the two shafts 20 being each supported on a pair of bearings 40, each bearing 40 being mounted on a sidewall 51 of the respective bearing case 50.

(12) Preferably, each end portion 20a of the shafts 20 carries a pair of eccentric weights 30 positioned externally to the respective pair of bearings 40, i.e., externally of the opposite sidewalls 51 of the respective bearing case 50 and which are generally sized to remain internal to the structural case 50.

(13) One of the shafts 20 is driven from any one of the drive units (not illustrated), the end portions 20a of the shafts 20 being positioned on each side of the vibrating screen 10, provided with gears 60 which allow the shafts 20 rotating together, with the same rotation, but in opposite directions, as schematically illustrated in FIGS. 3A, 3B, 3C, 3D and 4.

(14) Each of the end portions 20a of a shaft 20 carries a gear 60 engaged with a gear 60 carried by the adjacent end portion 20a of the other shaft 20, said gears 60 being housed within a same bearing case 50, between the two bearings 40 for supporting the respective end portion 20a of the shafts 20.

(15) Each of the end portions 20a of an shafts 20 carries at least one eccentric weight 30 with a total mass different from that one of the eccentric weight 30 carried by each of the end portions 20a of the other shaft 20, said shafts 20, engaged to each other by the gears 60, are rotatively driven in opposite directions at the same frequency and in determined phases to define the forward and upward inclination of the major longitudinal axis of the elliptical movement to be imparted on the screen deck 11 as shown in FIG. 3.

(16) The difference of the masses of the eccentric weights between the two shafts 20 defines the dimensional ratio between the major and minor axes of the elliptical movement of the screen deck 11.

(17) FIGS. 3 and 3A show the eccentric weights 30 in a first position corresponding to the elliptical, longitudinal and upward displacement of the screen deck 11, whereas FIGS. 3B, 3C and 3D illustrate the eccentric weights 30, of the two shafts 20, in positions representing the other three transversal displacements, transversal upward, longitudinal downward and transversal downward, respectively, of the screen deck 11 of the vibrating screen 10, according to the two axes of the desired elliptical movement.

(18) In the illustrated construction, each of the two bearing cases 50 is disposed on one side of the vibrating screen PV near to a respective sidewall 12 thereof. With this construction, the end portions 20a of each shaft, but preferably of only one of the two shafts 20 defining a drive shaft, are connected to each other by an intermediate portion 20b of the respective shaft 20, with the use of flexible couplings 20c, suitable and well known in the art.

(19) With the proposed construction, all the constituent elements of the mechanical vibrator VM, comprising the two bearing cases 50 and the shafts 20, are covered by a protective cowl 70 which is removably fixed by any suitable means on the beams as shown in FIGS. 1 and 2.

(20) For the maintenance of the mechanical vibrator VM, it is sufficient that the protective cowl 70 and the bearing cases 50 with the shafts 20 are easily detached from the beams 13, without the need for internal disassembling of the vibrating screen PV.

(21) The proposed construction allows obtaining the elliptical movement of the screen deck 11 by using a mechanical vibrator VM with only two shafts 20 mounted on a pair of bearing cases 50 which are easily and quickly assembled and disassembled from the beams 13 of the vibrating screen PV.

(22) The advantages of this construction are achieved by the assembly of the mechanical vibrator VM displaced well upwardly relative to the center of gravity of the vibrating screen PV, in a longitudinal position relative to the latter, which balances the eccentric, longitudinal and transversal impulses, on the feed and outlet portions of bulk material in relation to the screen deck 11, allowing a substantially constant flow of bulk material from its feed to its outlet of the screen deck 11.

(23) Although only one possible embodiment of the invention has been illustrated, it should be understood that changes in shape, number and relative arrangement of the component parts may be made without departing from the scope of protection defined in the claims accompanying this disclosure.