Conveyors: power-driven – Conveyor section – Reciprocating conveying surface
Reexamination Certificate
1998-07-06
2001-03-27
Ellis, Christopher P. (Department: 3651)
Conveyors: power-driven
Conveyor section
Reciprocating conveying surface
C198S750400, C198S850000, C198S817000, C198S853000
Reexamination Certificate
active
06206179
ABSTRACT:
FIELD OF INVENTION
The invention refers to a chain conveyor comprising a roller chain and a supporting rail for vertically supporting the roller chain. The roller chain comprises a plurality of supporting rollers which are interconnected by means of chain links.
The chain conveyors discussed herein are used in general in storage shelves of rack storage facilities where they serve as a conveying means for the goods to be stored. The conveying means is usually looped over two deflections to form an endless conveying means, whereby there is provided, as the real conveying means, a conveyor chain provided with rollers. In order to save costs and weight, however, not the entire circulating conveying means is constituted as chain, but only about half of it, while the other half is constituted by a strap.
As a support for the goods to be stored, in most cases pallets are used. Upon storing the goods, the latter ones are laid onto the conveyor chain and, mostly by means of a fork lift truck, pushed into the storage rack. If the need arises, the goods are pulled out again by this fork lift truck.
PRIOR ART
The document WO 94/00370 entitled “Pallet-Support Rail and Slide-in Pallet-Storage Unit with Pallet-Support Rails and Pallet-Conveyor Track” discloses a chain conveyor of the generic concept discussed herein. This conveyor is provided with a roller chain, the supporting rollers thereof being connected to each other on both sides by means of a pair of lateral link plates, whereby each second link of the chain is designed as supporting strap member. The lateral link plates project downwards to such an extent that they can laterally guide the upper run of the roller chain along the rail, whereby, for this purpose, the rail is smaller in its width than the mutual distance of the two link plates of a pair. In its lower portion, the rail made of aluminum comprises a return channel in which the lower run of the roller chain is received, guided and supported.
The problems in connection with the chain conveyor discussed above consist in that the lateral link plates of the roller chain have to take both tractive forces as well as guiding forces. Thus, the lateral link plates cannot be made continuously of a material which has good self-lubricating properties, like PTFE, but they have to be manufactured, at least partially, of a high-strength material, for example steel. This design results in the disadvantage that the frictional values between roller chain and guiding rail are relatively high. This is also particularly true for the lower chain run received in the return channel because here additionally the intrinsic weight of the roller chain has to be supported by the lateral link plates. Due to the high frictional values arising between roller chain and supporting rail, the constructional length of a chain conveyor with such a design is limited. Moreover, it has shown that the frictional resistance is additionally increased by the tractive load of the lateral link plates simultaneously designed as guiding means.
Further problems in connection with a chain conveyor as discussed herein before consist in the fact that the chains used hereby can take only tractive forces. As soon as thrust forces act on the chain, what is always the case upon loading of goods, the danger exists that the chain folds by the mutual rotation of particular chain links that are subjected to thrust forces.
Particularly that chain portion which is situated between the pallet to be pushed in and the goods already stored is subjected to thrust forces to a high extent. The pallet to be pushed in exerts a tractive force onto the chain portion situated behind that pallet and guided around the front deflection. Since such deflections have a very small diameter due to the limited available space, they have a bad efficiency and are not suited for high tractive forces. The tractive force in the chain deflected around the deflection is transmitted via the elastic strap to the rear deflection which further decreases the efficiency, whereby it is to be considered that the mass of the stored goods can amount up to 20 tons.
It is understood that a folding of the chain is most undesirable under the explained circumstances because the total length of the chain is suddenly changed by this folding; in an extreme case, this can result in a rupture of the strap and in a damage of the deflections. Moreover, by a folding of the chain, a distance between the goods, that possibly has to be observed for the protection of the stored goods, can be changed. Also, it can happen that particularly light weight goods are raised and rotated out of the horizontal position upon a folding of the chain.
A folding cannot be avoided when conventional chains are used because the total length of the chains and the circulating conveying means, respectively, can vary to a large extent due to for instance temperature changes and expansion of the strap.
OBJECTS OF THE INVENTION
Thus, it is the object of the invention to improve a chain conveyor of the kind referred to above such that the chain can also take and transmit thrust forces.
A further object of the invention consists in providing a chain conveyor that is designed with means for laterally guiding the roller chain, which are simply arranged and can be manufactured at low costs, whereby the guide means shall present very low frictional resistances between roller chain and support rail.
SUMMARY OF THE INVENTION
To meet this and other objects, the present invention provides a chain conveyor comprising a roller chain and a supporting rail for vertically supporting the roller chain. The roller chain comprises a plurality of supporting rollers which are interconnected by means of chain links. The chain links are provided with stop means that limit the mutual rotating movement of adjacent chain links exceeding a predetermined angle such that the roller chain can transmit thrust forces.
By providing chain links which have stop elements that limit a mutual rotation of adjacent chain links exceeding a certain angle of rotation in such a way that the roller chain can transmit thrust forces, the danger that particular portions of the chain are folded together is eliminated and the disadvantages connected thereto are avoided.
The chain links of the roller chain are interconnected by means of a hollow shaft member. The shaft member is designed simultaneously as a supporting axle for the supporting rollers. A discrete guiding element is inserted into the shaft member. The guiding element that towers below the chain link at least at one side toward the guiding rail.
REFERENCES:
patent: 3708059 (1973-01-01), Ackermann
patent: 4515578 (1985-05-01), Burger
patent: 5538384 (1996-07-01), Haldimann
patent: 495894 (1938-11-01), None
patent: 8911602 (1989-11-01), None
Bower Kenneth W
Ellis Christopher P.
Gilgen Fordersysteme AG
Tarolli, Sundheim, Covell Tummino & Szabo L.L.P.
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