GB2152853A - Roller screen - Google Patents

Abstract

For separating soil and stones from potatoes a plurality of spaced rotating rolls 1, 1a, 1b are surrounded by respective springs or screws 2 whose internal diameter is larger than the external diameter of the roll. Each roll has larger diameter end sections 3 joined to the central section by frusto-conical sections 4. These force the stones and soil out of the screw and prevent them becoming jammed. <IMAGE>

Description

SPECIFICATION Roller screen The invention relates to a roller screen forseparat- ing products and materials adhering thereto or being in between comprising a plurality of parallel spaced rotating rolls, each surrounded by a screw with a larger internal diameterthan the external diameter of the rolls.

Such rollerscreensareknowninthepriorart. For instance at lifting of potatoes the potatoes and the material adhering thereto and being inbetween, comprising soil and stones, are carried over a number of parallel provided rolls in a direction perpendicular to the longitudinal direction ofthe rolls. By rotating said rolls all in the same direction, the potatoes are conveyed and by the resistance ofthe rolls against the potatoes the soil adhering to the potatoes is removed.

As the rolls are placed at some distance from each other,the removed soil can fall down between the rolls.

Also devices are known, wherein about every roll the screw is concentrically provided. The screw functions to keep the stones, being inbetween the potatoes, at a distance, and to removethesoil adhering to the potatoes. Bythe weight and size the stones are engaged bythe screws andconsidering the direction of rotation and the sense of winding of the screw-conveyed to one extremity of the roll, such that these are disengaged and removed from the agricultural product. At the end ofthe screw the stones are discharged.

The known devices are made such that the stones abut atthe end of the screw against the frame ofthe deviceoragainstthe bearing coverofthe rolls. Said structure has the draw backthatthe stones are either shot away or are pulverized by the pressure exerted by the last coil of the screw. In this way either the rolls itselves orthe agricultural product can be damaged.

The invention aims to overcome above draw backs.

This object is realized with above mentioned roller screen in that the rolls being provided with at least one largerdiametersection,transfering in the remaining section of the roll by a conical transition section.

By this measure stones etc, being conveyed bythe screw cannot hitthe frame ofthe device oragainstthe bearing coverofthe rolls, but are carried for instance outwardly to the extremity of the roll by the conical transition section, after which the stones can fall through the intermediate space between the bearing cover and the rolls.

According to a preferred embodiment ofthe invention the conical transistion part has a length equal to or smaller than the pitch of the screw minus the diameter ofthewinding of the screw.

A stone being present is now lifted in one revolution of the roll from the cavity between the winding of the screw.

Accordingtoafurtherembodimentofthe roller screen the screws of adjacent rolls have an opposite sense of winding. In combination with a drive system - as is known perse-- it is possible to convey the stones on the one roll to the left hand side and on the other, adjacent roll,tothe right hand side if the rolls rotate in the same direction.

Now the invention will be described in more detail with reference to a preferred embodiment as illustrated in the figure, in which the rolls are shown surrounded with concentrically provided screws.

Referring to the figure a roll is indicated with 1 and a concentrically mounted screwwith 2. Adjacent to roll 1 roll 1 a is provided, besides which roll ibis mounted.

These rolls are all driven and their interspace can be adjusted in a manner known perseto be adapted for the material handled by the rollerscreen. Each roll is provided at both ends with a large diameter section 3, 3a, with a conical transfer section 4, 4a having a length no morethanthe pitch ofthescrew, minusthe diameterofthewinding ofthescrew.

The diameter of the large diameter section ofthe roll is such chosen that it just fits in the internal space of the screw. The device according to the shown embodimentcomprisesthree rolls, but also two or more than three can be provided.

It is also possible the roll being provided with several larger diametersections with conical transfer section, so not alone at the extremities, buth for instance also in the middle ofthe roll.

In the figure, indicated with 5, a stone isshown, which is engaged by screw 2, and -- considering the direction of rotation and the sense of winding ofthe screw- is transported in the direction shown by arrow 6. As soon as stone 5 reaches the conical transfer section 4 and the larger diameter section 3, it is forced outwardly and will drop in the opening being provided between the rolls and the bearing cover 6.

Roll lain the figure rotates in the same direction as roll 1,howeverthesenseofwinding of screw lairs opposite to that of roll 1, by which the stones are conveyed in opposite direction to that of roll 1.The stones are pressed outwardly by the conical transfer section 4a and the larger diameter section 3a. Thereupon the next roll ibis provided with a screw being equal to roll 1. In this way the alternating transportfor the stones to the one side and to the other side is provided.

The potatoes remained above the screws are stripped of soil adhering thereon bythefriction of the screws againstthesurface ofthe potatoes. Both soil and stones can be intercepted by a conveyor band under the rolls, of which the longitudinal direction is parallel to the rolls. So soil and stones can be removed.

1. Rollerscreenforseparating products and materials adhering to it or being inbetween, comprising a plurality parallel spaced rotating rolls, each surrounded bya screw with a larger internal diameter than the external diameter ofthe rolls, characterized in thatthe rolls are provided with at least one larger diameter section, transferring in the remaining part of the roll by a conical transition section (4).

2. Roller screen according to claim 1, characterized in that, the conical transition section (4) has a length equal to or smaller than the pitch of the screw minus the diameter ofthe winding ofthe the screw.

3. Roller screen according to claim 1 or2, characte rizedin thatthe diameter ofthe lager diameter section equals the internal diameter ofthe screw.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Roller screen The invention relates to a roller screen forseparat- ing products and materials adhering thereto or being in between comprising a plurality of parallel spaced rotating rolls, each surrounded by a screw with a larger internal diameterthan the external diameter of the rolls. Such rollerscreensareknowninthepriorart. For instance at lifting of potatoes the potatoes and the material adhering thereto and being inbetween, comprising soil and stones, are carried over a number of parallel provided rolls in a direction perpendicular to the longitudinal direction ofthe rolls. By rotating said rolls all in the same direction, the potatoes are conveyed and by the resistance ofthe rolls against the potatoes the soil adhering to the potatoes is removed. As the rolls are placed at some distance from each other,the removed soil can fall down between the rolls. Also devices are known, wherein about every roll the screw is concentrically provided. The screw functions to keep the stones, being inbetween the potatoes, at a distance, and to removethesoil adhering to the potatoes. Bythe weight and size the stones are engaged bythe screws andconsidering the direction of rotation and the sense of winding of the screw-conveyed to one extremity of the roll, such that these are disengaged and removed from the agricultural product. At the end ofthe screw the stones are discharged. The known devices are made such that the stones abut atthe end of the screw against the frame ofthe deviceoragainstthe bearing coverofthe rolls. Said structure has the draw backthatthe stones are either shot away or are pulverized by the pressure exerted by the last coil of the screw. In this way either the rolls itselves orthe agricultural product can be damaged. The invention aims to overcome above draw backs. This object is realized with above mentioned roller screen in that the rolls being provided with at least one largerdiametersection,transfering in the remaining section of the roll by a conical transition section. By this measure stones etc, being conveyed bythe screw cannot hitthe frame ofthe device oragainstthe bearing coverofthe rolls, but are carried for instance outwardly to the extremity of the roll by the conical transition section, after which the stones can fall through the intermediate space between the bearing cover and the rolls. According to a preferred embodiment ofthe invention the conical transistion part has a length equal to or smaller than the pitch of the screw minus the diameter ofthewinding of the screw. A stone being present is now lifted in one revolution of the roll from the cavity between the winding of the screw. Accordingtoafurtherembodimentofthe roller screen the screws of adjacent rolls have an opposite sense of winding. In combination with a drive system - as is known perse-- it is possible to convey the stones on the one roll to the left hand side and on the other, adjacent roll,tothe right hand side if the rolls rotate in the same direction. Now the invention will be described in more detail with reference to a preferred embodiment as illustrated in the figure, in which the rolls are shown surrounded with concentrically provided screws. Referring to the figure a roll is indicated with 1 and a concentrically mounted screwwith 2. Adjacent to roll 1 roll 1 a is provided, besides which roll ibis mounted. These rolls are all driven and their interspace can be adjusted in a manner known perseto be adapted for the material handled by the rollerscreen. Each roll is provided at both ends with a large diameter section 3, 3a, with a conical transfer section 4, 4a having a length no morethanthe pitch ofthescrew, minusthe diameterofthewinding ofthescrew. The diameter of the large diameter section ofthe roll is such chosen that it just fits in the internal space of the screw. The device according to the shown embodimentcomprisesthree rolls, but also two or more than three can be provided. It is also possible the roll being provided with several larger diametersections with conical transfer section, so not alone at the extremities, buth for instance also in the middle ofthe roll. In the figure, indicated with 5, a stone isshown, which is engaged by screw 2, and -- considering the direction of rotation and the sense of winding ofthe screw- is transported in the direction shown by arrow 6. As soon as stone 5 reaches the conical transfer section 4 and the larger diameter section 3, it is forced outwardly and will drop in the opening being provided between the rolls and the bearing cover 6. Roll lain the figure rotates in the same direction as roll 1,howeverthesenseofwinding of screw lairs opposite to that of roll 1, by which the stones are conveyed in opposite direction to that of roll 1.The stones are pressed outwardly by the conical transfer section 4a and the larger diameter section 3a. Thereupon the next roll ibis provided with a screw being equal to roll 1. In this way the alternating transportfor the stones to the one side and to the other side is provided. The potatoes remained above the screws are stripped of soil adhering thereon bythefriction of the screws againstthesurface ofthe potatoes. Both soil and stones can be intercepted by a conveyor band under the rolls, of which the longitudinal direction is parallel to the rolls. So soil and stones can be removed. CLAIMS

1. Rollerscreenforseparating products and materials adhering to it or being inbetween, comprising a plurality parallel spaced rotating rolls, each surrounded bya screw with a larger internal diameter than the external diameter ofthe rolls, characterized in thatthe rolls are provided with at least one larger diameter section, transferring in the remaining part of the roll by a conical transition section (4).

2. Roller screen according to claim 1, characterized in that, the conical transition section (4) has a length equal to or smaller than the pitch of the screw minus the diameter ofthe winding ofthe the screw.

3. Roller screen according to claim 1 or2, characte rizedin thatthe diameter ofthe lager diameter section equals the internal diameter ofthe screw.

4. Roller screen according to claim 1 and 2, characterized in thatthe screws on subsequent rolls having an opposite sense ofwiding.

5. Rolling screen according to any ofthe preceding claims, characterized in thatthe larger diameter section is provided at the end of each roll (1).