MALAGOLI, Uber (Via J.F. Kennedy 21, Rubiera, I-42048, IT)
| Claims.
1). A horizontal vibrating screen, comprising: a first conveyor plane (2), provided with a plurality of through-holes (2a) of a predetermined size and shape; a continuous second conveyor plane (3) located beneath the first conveyor plane (2); means for supplying (4), predisposed to supply a material to be screened (100) onto the first conveyor plane (2); a motor (5) predisposed to impart a vibrating motion on the first conveyor plane (2) and the second conveyor plane (3) which vibrating motion exhibits at least a component which is parallel to the first conveyor plane (2) and the second conveyor plane (3) and at least a component which is perpendicular thereto; wherein it comprises at least a third conveyor plane (6) provided with a plurality of through-holes (6a) having a predetermined size and shape, the at least a third conveyor plane (6) being arranged beneath the second conveyor plane (3) and being supplied in parallel with the first conveyor plane (2) by the means for supplying (4), the motor (5) being predisposed to invoke on the third conveyor plane (6) too a vibrating motion which exhibits at least a component which is parallel to the the first conveyor plane (2) and the third conveyor plane (6) and at least a component which is perpendicular thereto.
2). The screen of claim 1, wherein the means for supplying (4) comprise a hopper (4) provided with a first channel (4a) predisposed for supplying the first conveyor plane (2), and a second channel (4b) predisposed for supplying the third transport plane (6). 3). The screen of claims 1 or 2, wherein a collection plane (7) is located beneath the third conveyor plane (6).
4). The screen of at least one of the preceding claims, wherein the motor (5) comprises at least a rotating cam element (15) which is mechanically connected to the first conveyor plane (2), the second conveyor plane (3) and the third conveyor plane (6).
5). The screen of claim 4, wherein the motor (5) comprises three rotating cam elements (15, 16, 17) which are reciprocally coplanar and parallel, a first rotating cam element (15) and a third rotating cam element (17) rotating in a first direction and a second rotating cam element (16), located in an intermediate position to the first rotating cam element (15) and the third rotating cam element (17) rotating in an opposite direction to the first direction. |
A Horizontal Vibrating Screen.
Technical Field
The invention relates to a horizontal vibrating screen. Horizontal vibrating screens are commonly used for selecting and subdividing loose granular material, typically such as gravel and/or sands, on the basis of the size or shape of the granules, or particles. Background Art
Vibrating screens of known type comprise a plurality of conveyor planes which are superposed and positioned parallel to one another. Each conveyor plane exhibits a series of perforations, through which the material to be selected transits from an upper plane to an underlying plane. The size of the perforations decreases going from the conveyor plane arranged superiorly to the conveyor plane arranged inferiorly. In this way, the largest-size particles are kept on the upper conveyor plane while the smaller particles are gradually retained on the various inferiorly-arranged planes. The material is supplied in a layer to the upper plane of the screen. The conveyor planes are powered by cam motor devices of known type. The motor devices impose a vibrating motion on the conveyor planes, which vibrating motion has at least a horizontal component and at least a vertical component. The two components of the motion are synchronised such that the granules and particles arranged on the various conveyor planes follow a motion the trajectory of which is overall elliptical and lying on a vertical plane. The motion impressed on the granules or particles thus also exhibits a horizontal component which represents the overall advancing of the
material along each conveyor plane. The jiggling of the material causes a progressive layering which places the smallest-sized particles towards the base of the layer of material. The greater the magnitude of the jumping action, the better the material screening quality, i.e. the precision with which the granules are sub-divided by size on the various planes. However, the greater the jumping magnitude of the material, the slower the overall advancing velocity of the material and thus the poorer the productivity level of the screen. In an industrial choice between the need to guarantee a precise screening and obtaining high screening productivity, usually the former is given precedence as the processes and operations subsequently using the screened material need the material to be very homogeneous in terms of size of the granules or particles, especially when dealing with sands. Disclosure of Invention The aim of the present invention is to provide a horizontal vibrating screen which offers precise screening while at the same time providing greater productivity with respect to screens of known type.
Further characteristics and advantages will better emerge from the detailed description that follows, made herein below with reference to the accompanying figures of the drawings, provided by way of non-limiting example, and in which: figure 1 is a perspective view of the screen of the present invention, with some parts of the support frame removed in order better to evidence other parts of the screen; figure 2 is a section view along a vertical longitudinal plane of the device of figure 1.
With reference to the figures of the drawings, the horizontal vibrating screen 1 the horizontal vibrating screen 1 of the present invention
comprises a first conveyor plane 2 provided with a plurality of through- holes 2a of a predetermined size and shape. A second conveyor plane 3 is located below the first conveyor plane 2, which second conveyor plane 3 is continuous, i.e. without perforations. A third conveyor plane 6, provided with a plurality of through-holes 6a having predetermined shape and size, is located below the second conveyor plane 3. A mobile collection plane 7 is positioned below the third conveyor plane 6, which mobile collection plane 7 is preferably constituted by a conveyor belt. In the preferred embodiment of the invention all the planes are substantially horizontally arranged, but might also be arranged in an inclined position with respect to the horizontal.
The conveyor planes and the collection plane are associated to a support frame 10 provided with at least two rest elements 11 for resting the screen on the ground or on a vehicle or a transport carriage. In particular, the support frame 10 comprises at least three couples of longitudinal elements 20, 30, 60 which are associated to the longitudinal edges of the first, the second and the third conveyor planes. Each of the conveyor planes is further supported by a plurality of bars, arranged parallel to the longitudinal elements and supported in turn by crossbars, which are only partially visible in figure 1.
The first and the third conveyor planes 2, 6 are supplied in parallel by means for supplying 4 associated to the support frame 10. The means for supplying 4 comprise a hopper 4 provided with a first channel 4a, predisposed to supply the first conveyor plane 3, and a second channel 4b, predisposed to supply the third conveyor plane 6. The material to be screened 100 is directed by the hopper 4 towards the first and the third conveyor plane on which it is arranged in layers. The material can be supplied to the hopper 4 in various ways, for example by means of a
conveyor belt a discharge position of which is positioned above an inlet opening of the hopper, as illustrated in figure 2.
A motor 5 is predisposed to impose a vibrating motion on the conveyor planes 2, 3, 6, which vibrating motion exhibits at least a component A which is parallel to the conveyor planes and at least a component S which is perpendicular to the planes. The motor 5 comprises at least a rotating cam element 15, mechanically connected to the conveyor planes 2, 3, 6 and rotated by a motor (not illustrated). The motor 5 preferably comprises three rotating cam elements 15, 16, 17 which are coplanar and parallel, which are mechanically connected to the conveyor planes 2, 3, 6. A first and a third rotating cam elements rotate in a direction, while a second cam element, located in an intermediate position to the other two, rotates in an opposite direction to the other two. The angular staggering of the three rotating cam elements can be regulated to determine the characteristics of the overall motion of the conveyor planes.
The two components of the vibrating motion of the conveyor planes are transferred to the material to be screened 100 such that the granules and particles which make up the material to be screened 100 also undergo a motion which exhibits at least a horizontal component A 5 which represents the overall advancing of the material along each conveyor plane, and a vertical component S, which causes a continual jumping of the material on each conveyor plane. The jumping of the material causes a progressive layering of the granules or particles which sort the smallest-sized particles to the base of the layer of material. The greater the amplitude of the jumping motion of the material, the more total and precise the layering of the material, i.e. the material becomes arranged in well-distinguished layers in which a high level of dimensional homogeneity exists among the granules and particles.
Differently to what happens in known-type screens, in which the material is supplied only to the uppermost plane, in the screen of the present invention the material 100 is contemporaneously supplied onto two planes, the first plane 2 and the third plane 6. The screen of the present invention advantageously decidedly privileges the jumping motion over the advancement motion of each conveyor plane, inasmuch as the smaller overall advancement of the material is compensated for by the fact that the screen comprises at least two main screening lines, respectively comprising the first and the third conveyor planes 2, 6. This leads to a high level of material screening quality, i.e. high-level precision with which the granules are sub-divided by size onto the various planes, as the smaller-sized granules can freely flow through the first 2 and the third 6 conveyor planes. In this way a very high percentage of granules or particles of smaller size than those of the holes 2a, 6a of the first and the third transport plane separate from the material 100 and deposit on the second conveyor plane 3 and below the third conveyor plane 6, without staying mixed-up with the larger-sized granules which are retained on the first and the third conveyor planes. In the case, for example, of screening more-or-less fine sands from a gravelly material the screen enables separation of a very high percentage of sand from the overall mass of the gravelly material, considerably increasing the quantity of sand produced in a single time unit.