Conveyors: power-driven – Conveyor section – Endless conveyor
Reexamination Certificate
2003-09-29
2004-08-17
Ridley, Richard (Department: 3651)
Conveyors: power-driven
Conveyor section
Endless conveyor
C198S810030, C198S840000
Reexamination Certificate
active
06776280
ABSTRACT:
The present invention relates to a belt guidance unit for centring a conveyor belt, which during operation is susceptible to lateral displacement away from a neutral position in its longitudinal direction. According to the invention the belt guidance unit can be employed on conveyor belts that move in one direction as well as in two opposite directions with only very slight alterations and the basic constructional features of the belt guidance unit are substantially identical in the two operational situations.
The belt guidance unit according to the present invention is used for guiding conveyor belts particularly in the field of processing plants for various types of materials in bulk format, such as granulated ores, etc.
In connection with plants where such conveyor belts are employed, it is known that for various reasons the belts “wander” laterally on rollers and along their tracks. This is due in part to uneven loading, partly to misalignment of supports and rollers and often a combination of several different factors that produce a random pattern of movement for lateral movement of the belt. This lateral movement may be defined as a deviation from a basic neutral position where the belt travels in its longitudinal direction along an imaginary centre line or other kind of desired path over rollers or guides. Lateral movement in the belt will move the belt to the side of this neutral position or path for the belt, whereupon it should be restored to this neutral position. This creates the need for a guiding device that senses when the belt is out of the neutral position, whereupon it corrects the belt's travel in its longitudinal direction, thus returning the belt to the neutral position. This should also be a dynamic correction device that constantly corrects the belt relative to positions on both sides of the neutral position as well as preferably in relation to both directions of travel in the belt's longitudinal direction.
A belt guidance unit for the above-mentioned tasks and areas of application should furthermore be simple and robust to operate while it must be easy to install and adjust before use. The construction should furthermore be capable of being adapted to the existing conditions and loads either by employing different dimensions for the constructional parts or by being able to adjust the design of the constructional parts that are already installed in an existing system, such as, e.g., rollers, guides, mounting brackets, etc.
A belt guidance unit, moreover, should be able to be adapted for a conveyor belt that moves in one or two directions without major constructional alterations.
From previously known solutions within the field, a device may be mentioned for conveyor belts that travel over rollers or supports, described in DE 174 491, which device corrects for lateral displacements that occur in the belt during operation, causing the belt to be returned to its neutral position. A set of guide rollers for the conveyor belt is mounted on a plate, which is rotatably attached to the base. To the rotatable plate is mounted an arm with a tie bar. The arm may be articulated and rotatable about a pivot that is attached to the base. To the tie bar are attached guide rollers, which move along the edge of the conveyor belt and which, in the event of lateral displacement of the belt, transfer the movement to the tie bar. The movement is transferred to the lever arm, which in turn transfers the movement to the plate, thus causing the guide rollers' axes to be tilted and returning the conveyor belt to its neutral position.
The belt guidance unit described in NO 178 853 is a known solution of a similar type, but where the lever arm is rotatably attached both to the plate holding the guide rollers and the tie bar holding the guide rollers. The lever arm is rotatably attached to a fixed point located at a distance from the rotatable attachments in the plate and the tie bar, and a rotatably parallel stay is mounted parallel to the lever arm, between the tie bar and a fixed base in the form of a beam, with the result that the tie bar always remains at right angles relative to the conveyor belt's centre line.
In NO 306 708, moreover, a reversible belt guidance unit is described for centring conveyor belts, which during operation are susceptible to a lateral displacement away from a neutral position, comprising a rotating mechanism, which carries at least one guide roller for the conveyor belt, and which is rotatably mounted in a first fixed beam, which rotatable mounting is arranged about an axis that is perpendicular to the conveyor belt. Furthermore, a first set of guide rollers abuts against the conveyor belt's lateral edges, thereby being displaced laterally depending on the conveyor belt's lateral displacement, and the belt guidance unit comprises a first transfer mechanism for transferring the lateral displacement of the first set of guide rollers to the rotating mechanism, for rotating the guide roller to a position where it guides the conveyor belt towards the neutral position.
Known belt guidance units of the type described in DE 174 491 and the like have a tendency to produce rolling and skewed travel in the conveyor belt, particularly when there is uneven loading or uneven weight distribution, resulting in wear along the edge of the belt.
Compared to these other known belt guidance units, the belt guidance unit known from NO 178 853 provides a far smoother movement of the conveyor belt, resulting in less wear and a longer life for the belt. The belt guidance unit described in NO 178 853, however, only works when the belt moves in one direction, which is not sufficient for a number of purposes.
Furthermore, the belt guidance unit from NO 306 708 is designed so as to work with conveyor belts that move in two opposite directions.
The above-mentioned solutions, however, are relatively complicated in their mechanisms for producing movement and the solutions are therefore expensive and complicated with regard to mounting and adjustment, while also requiring some inspection.
It is therefore an object of the present invention to provide a guide device or a belt guidance unit according to the above wishes and requirements that counteracts the disadvantages and defects attached to previously known solutions.
The belt guidance unit for centring a conveyor belt according to the present invention guides a conveyor belt, which during operation is susceptible to lateral displacement relative to a longitudinal neutral position.
The belt extends over a guide roller mounted substantially across the belt's direction of travel, which guide roller is rotatably mounted in a holder about an axis substantially across the belt's direction of travel, which holder for the guide roller is rotatably mounted on a base about a substantially perpendicularly extending axis relative to the conveyor belt's direction of travel. According to the present invention, between the holder for the guide roller and the base there is mounted a rotationally elastic element, which in a neutral position gives the holder for the guide roller a rotational displacement to a first side relative to the conveyor belt's direction of travel. The rotationally elastic element is tightened when the holder is brought towards a neutral position relative to the conveyor belt's direction of travel. Furthermore, in connection with the holder or the guide roller, at a distance from the holder's rotational axis about the base, there is mounted at least one arm with a guide device at a distance from the holder, which guide device is mounted at the conveyor belt's lateral edge.
In an alternative embodiment for conveyor belts that move in two opposite directions (reversible conveyor belts), the conveyor belt is guided by the belt guidance unit, which conveyor belt is susceptible during operation to lateral displacement relative to a longitudinal neutral position. The belt extends over a guide roller mounted substantially across the belt's direction of travel, whi
Gaarden Kjell Arne
Hovstø Kenneth
Barnes & Thornburg LLP
Martin Engineering Company
Ridley Richard
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