The present invention relates to a screen with disk rollers, which is particularly, although not exclusively, useful and practical for use in the process of separation and screening of urban solid waste, which is commonly carried out as part of the treatment of waste in order to separate elements of different size before the disposal or recycling thereof.

In general, the screen is an apparatus whose purpose is to separate elements of different sizes which make up an aggregate of unconnected materials in pieces, such as for example urban solid waste, or in powder form.

In the sector, the term is used especially to indicate the mechanical devices used to separate aggregates into various size classes, and such mechanical devices are employed in various different fields of industry, such as the waste treatment industry, the chemical industry, the extraction industry, and also in the construction of buildings or roads.

Nowadays, conventional screens can be divided into two main types: screens with nets and screens with disk rollers.

A screen with a net, as may be readily understood from its name, is constituted substantially by a net, the meshes of which can have a constant or increasing diameter.

In a screen with a net, the aggregates to be screened are moved and made to advance on the surface of the net of the screen and, thanks to this movement, the elements that are smaller than the meshes, i.e. than the holes, which are contained in the net of the screen pass through the net and fall into the collection region below.

In particular, in a screen with a net with meshes of increasing diameter, the smaller elements of the aggregates to be screened pass through the net of the screen, thus falling into the collection region, at the level of the initial area of the net with narrower meshes, while the larger elements of the aggregates to be screened fall into the collection region at the level of the final area of the net, with wider meshes.

In this way, in fact, it is possible to separate multiple size classes of the elements of the aggregates to be screened, so that the smaller elements are collected in a region intended only for them, while the larger elements are collected in another region intended only for them.

Such type of conventional screens suffers some drawbacks, however, in that such screens with nets must be supplied with a large amount of energy in order to be actuated, and they are thus very wasteful from the point of view of energy consumption, and furthermore they necessitate a complex system for the advancement of the aggregates to be screened.

A screen with disk rollers, on the other hand, is constituted substantially by a series of mutually parallel rotating rollers, each one of which is in turn constituted by a central shaft on which disks are fixed in a perpendicular position with respect to the shaft. All the rollers of such a screen rotate in a same direction of rotation, and the spacing, i.e. the distance, between the rollers of such a screen and between the disks of a same roller can be constant or increasing.

In particular, in a screen with disk rollers with increasing spacing, the aggregates to be screened are loaded onto the first rollers with reduced spacing, which transport the remaining elements of the aggregates to be screened toward the subsequent rollers with wider spacing.

In this manner the smaller elements of the aggregates to be screened fall almost immediately into the spaces between the first rollers and between the corresponding disks, while the larger elements of the aggregates to be screened continue onward to the subsequent rollers and the corresponding disks.

However, such screens with disk rollers also exhibit some drawbacks, in that elongated elements of the aggregates to be screened, such as for example a filament or a sheet of plastic, in particular if wet, can clog the rollers, winding around them and creating tangles that obstruct the spaces between the rollers and between the disks, through which the elements of the aggregates to be screened should fall into the collection region below.

Screens with disk rollers are known, which were developed for the purpose of solving the above mentioned problems found in screens with disk rollers, which also comprise anti-clogging elements, which are constituted by cylindrical tubes arranged around the shafts between the adjacent disks of a same roller, and which are also known as idle tubes since they rotate freely about these shafts.

This latter type of screens with disk rollers with anti-clogging tubes also exhibits some drawbacks, however. In fact, when screening some specific types of aggregates, such as for example urban solid waste, the thinner, filament-shaped elements get trapped in the aperture comprised between the disks of the rollers and the anti-clogging tubes.

This causes the jamming of the anti-clogging tube on the disk fixed on the shaft of the roller and results in the anti-clogging tube rotating together with the disk, and thus together with the roller, instead of rotating freely about the shaft of the roller. Thus the elements of the aggregates to be screened, loaded into the screen with disk rollers with anti-clogging tubes, in advancing, encounter the mass made up of the idle tube, the disk of the roller and the trapped material, and tend to build up around it.

Furthermore the problems found in normal screens with disk rollers are not entirely solved in screens with disk rollers with anti-clogging tubes, since such idle tubes, by being arranged and resting on the shafts of the rotating rollers, still turn with the rollers, which transmit their rotary motion to the idle tubes, even if only partially.

This slow and partial rotation of the idle tubes, in fact, can enable the elongated elements of the aggregates to be screened, such as for example a filament or a sheet of plastic, in particular if wet, to rest on an idle tube and to turn on and with it, as a consequence winding around the idle tube and creating a tangle that comes to obstruct the spaces between the rollers and between the disks, through which the elements of the aggregates to be screened should fall into the collection region below.

The aim of the present invention is to overcome the above mentioned drawbacks of the known art by devising a screen with disk rollers, which is particularly, although non exclusively, useful and practical for use in the process of separation and screening of urban solid waste, which makes it possible to impede the rotation of the idle anti-clogging tubes if the filament-shaped elements that form part of the aggregates to be screened are trapped in the slot comprised between the disks of the rollers and the idle tubes.

Within this aim, an object of the present invention is to conceive a screen with disk rollers which makes it possible to prevent the rollers from being clogged by elongated elements of the aggregates to be screened, which can wind around the idle tubes, or more generally around the rollers, thus obstructing the spaces between the rollers and between the disks, through which the elements of the aggregates to be screened should fall into the collection region below.

Another object of the present invention is to devise a screen with disk rollers which makes it possible to avoid shutting down the screen in order to carry out maintenance operations adapted to the removal of the material trapped between the rollers and between the disks.

Another object of the present invention is to conceive a screen with disk rollers which makes it possible to use a simple, effective and efficient system for advancing the aggregates to be screened.

Another object of the present invention is to devise a screen with disk rollers which makes it possible to minimize the energy consumption necessary in order to be actuated.

Another object of the present invention is to provide a screen with disk rollers which is highly reliable, easily and practically implemented and low cost.

This aim and these and other objects which will become better apparent hereinafter are achieved by a screen with disk rollers, comprising a plurality of mutually parallel rollers that are installed on a supporting structure and actuated by way of at least one motor and means for transmission in a same direction of rotation, said rollers being each constituted by a shaft on which a plurality of disks is fixed, characterized in that said rollers comprise idle tubes arranged between pairs of said adjacent disks, said idle tubes being provided with rods adapted to mechanically prevent the complete rotation of said idle tubes.

Further characteristics and advantages of the invention will become better apparent from the description of a preferred, but not exclusive, embodiment of the screen with disk rollers according to the invention, which is illustrated by way of non-limiting example in the accompanying drawings wherein:

• Figure 1 is a sectional perspective view of a possible embodiment of the screen with disk rollers according to the present invention;
• Figure 2 is a perspective view of the detail of the rollers of a possible embodiment of the screen with disk rollers, according to the present invention;
• Figure 3 is a perspective view from below of a possible embodiment of the screen with disk rollers according to the present invention.

With reference to the figures, the screen with disk rollers according to the invention, which is generally designated by the reference numeral 10, comprises substantially a plurality of mutually parallel rotating rollers 30, each one of which is in turn constituted by a central shaft 35 on which disks 40 are fixed, such rollers 30 being installed on a frame 20.

The frame 20, or more generally the supporting structure of the screen with disk rollers 10, is preferably made of metal and fulfils a plurality of functions. Firstly, it supports and aligns the rollers 30 of the screen 10 proper, by acting as accommodation for their corresponding shafts 35; secondly, it keeps the aggregates to be screened inside the screen 10, thus preventing the egress of elements of the aggregates to be screened into the surrounding work environment; lastly, it covers and protects the means of transmission of the movement to the rollers 30 from the aggregates to be screened placed inside the screen 10 and from other external sources of disturbance that could compromise the correct operation of the screen 10 proper.

In an embodiment, the frame 20 can also be configured to incline the plane of the rollers 30, by way of adapted mechanisms, preferably hydraulic, in order to optimize the process of screening the aggregates.

The rollers 30 are installed on a same level inside the frame 20 by way of adapted receptacles 22, which are provided on the inner surfaces of the frame 20 and are adapted to accommodate the ends of the shafts 35 of the rollers 30.

In a different embodiment, the rollers 30, and thus the shafts 35, can also be positioned in the frame 20 on several different levels, in order to obtain an "up-and-down" effect that is adapted to overturn the flat elements of the aggregates to be screened, which otherwise would risk remaining on the rollers 30 of the screen with disk rollers 10.

The position of such receptacles 22 in the frame 20 is conveniently designed in such a way that the rollers are installed and kept in a mutually parallel position. The position of the receptacles 22 in the frame 20 also defines the spacing, i.e. the distance, between the rollers 30 of the screen 10, and such spacing can be constant or increasing.

With constant spacing, the distance between one roller 30 and the next is always the same, for example always equal to 10 centimeters. But with increasing spacing, the distance between one roller 30 and the next progressively increases, for example 10 centimeters between the first roller 30 and the second roller 30, 12 centimeters between the second roller 30 and the third roller 30, 14 centimeters between the third roller 30 and the fourth roller 30, and so on.

The rollers 30 are actuated by a motor 25, whose rotary motion is transmitted to the shafts 35 of the rollers 30 by way of transmission means that are comprised in the frame 20.

In a different embodiment, the screen with disk rollers 10 can also comprise more than one single motor 25; for example it is possible to install two or three motors 25 associated with inverters that regulate their speed, in order to actuate different groups of rollers 30 according to different rotation speeds, again by transmitting such rotary motion to the shafts 35 of the rollers 30.

Once put in motion, the rollers 30 rotate in a same direction of rotation and their rotation speed can be the same for all the rollers 30 of the screen 10 or it can be differentiated on the basis of the position of the rollers 30, optionally being adjustable by an operator.

Fixed on each shaft 35, which constitutes the element that supports a roller 30, disks 40 are provided, which preferably are hexagonal and preferably are made of carbon steel. Furthermore, on the rim of each disk 40 there is a band 42 that protrudes perpendicular to the surface of the disk 40 proper.

Thanks to the hexagonal shape of the disks 40, the screen with disk rollers 10 can be used not only for separating the elements of the aggregates to be screened, but also for spreading out an aggregate of unconnected materials over a larger surface, since the rollers 30 are capable of jolting such unconnected materials until they are arranged over a greater surface. This characteristic is very useful, particularly in view of the subsequent treatments of urban solid waste, which involve the use of feeders, optical readers, metal separators, etc.

The disks 40 are fixed on the corresponding shaft 35 in position that is perpendicular with respect to the shaft 35, and, being fixed, they follow the rotary motion of the shaft 35 on which they are fixed, once this is actuated.

The spacing, i.e. the distance, between the disks 40 of a same roller 30 of the screen 10 can be constant or increasing. With constant spacing, the distance between one disk 40 and the adjacent disk 40 is always the same for all the rollers 30, for example always equal to 5 centimeters. But with increasing spacing, the distance between one disk 40 and the adjacent disk 40 progressively increases, for example 5 centimeters between one disk 40 and the next in the first roller 30, 7 centimeters between one disk 40 and the next in the second roller 30, 9 centimeters between one disk 40 and the next in the third roller 30, and so on.

In the spaces between the pairs of adjacent disks 40 on a same roller 30, anti-clogging tubes 45 are provided, also known as idle tubes, which are arranged around the shafts 35 and are not fixed to them, and thus are not fixed to the rollers 30, but instead surround the part of the shafts 35 that is comprised between two adjacent disks 40 and rotate freely about those shafts 35.

The idle tubes 45 are in practice constituted by cylindrical tubes that have a larger diameter with respect to the diameter of the shaft 35 and a length that is equal to the distance between the two adjacent disks 40 on the same roller 30.

The idle tubes 45 are made preferably of hard plastics or of metal and have a mechanical impediment to their rotation which is constituted by anti-rotation rods 50 that are installed, one per each idle tube 45, in the lower part.

The rods 50 allow the idle tubes 45 to oscillate to the right or to the left, but not to rotate completely about themselves, thus producing a mechanical impediment to the 360° rotation of the idle tubes 45. The direction of oscillation of the idle tubes 45, and thus also of the rods 50, is perpendicular to the rollers 30 of the screen 10.

The rods 50 are preferably made of carbon steel and are conveniently sized in order to impact, during rotation, against the disks 40 of the previous roller 30 or of the subsequent roller 30, so that such impact mechanically blocks the rotary motion of the idle tubes 45, which otherwise would be able to rotate because they are locked to the disks 40 by filament-shaped elements trapped in the slot comprised between the disks 40 of the rollers 30 and the idle tubes 45, or because they are moved by the rollers 30 which partially transmit their rotary motion to the idle tubes 45.

In practice it has been found that the invention fully achieves the set aim and objects. In particular, it has been seen that the screen with disk rollers thus conceived makes it possible to overcome the qualitative limitations of the known art, in that it makes it possible to increase the operating effectiveness of the screen, by preventing the formation of blockages and tangles of material, with the consequent clogging of the rollers, and by preventing the shutdown of the screen for the removal of material trapped between the rollers and between the disks.

The elements of the aggregates to be screened thus manage to advance along the entire length of the screen 10 and the only jammed elements would be the filament-shaped elements of sufficiently fine thickness as to become trapped in the slot comprised between the disks of the rollers and the idle tubes.

Although the screen with disk rollers according to the invention has been conceived of in particular for use in the process of separation and screening of urban solid waste, which is commonly carried out in the treatment of waste before the disposal or recycling thereof, it can also be used, more generally, for screening aggregates in which the elements, owing to their shape or their composition, tend to become trapped in the rollers, obstructing the spaces between the rollers themselves and between their disks.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; by way of non-limiting example, the person skilled in the art will understand without effort that an electronic control system can also be provided for the screen with disk rollers, which enables an operator to start or stop the screen, to adjust its speed, etc. Moreover, all the details may be substituted by other, technically equivalent elements.

In practice the materials employed, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

In conclusion, the scope of protection of the claims shall not be limited by the explanations or by the preferred embodiments illustrated in the description by way of examples, but rather the claims shall comprise all the patentable characteristics of novelty that reside in the present invention, including all the characteristics that would be considered as equivalent by the person skilled in the art.

The disclosures in Italian Patent Application No. MI2014A000518 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.