Roller conveyors are commonly used in many industries to move packages or materials. In general, a conveyor roller comprises a plurality of individual rollers mounted between two parallel frames. The roller typically comprises a tube having a bearing in each end thereof which is rotatably journaled on a roller shaft that extends longitudinally through the tube. The roller shaft protrudes from each end of the roller tube and engages mounting holes in the frame.
Frequently, the roller shaft not only serves to mount the roller, but also functions as a structural element of the conveyor frame. In such cases, the ends of the shaft are drilled and tapped. Bolts extending from the outside of the frame are threaded into the tapped holes in the roller shaft to secure the frame members and rollers together. This approach to the construction of conveyors makes assembly of the conveyor time consuming and difficult. Moreover, this method of constructing conveyors makes it difficult to replace a single roller.
Another method to mount rollers in a conveyor frame is to use a roller having a through-shaft which is spring-loaded. In this case, the frame members are held together independently by a series of cross members rather than through the rollers. The rollers generally are installed after the frame is assembled. To install the roller, the shaft is moved axially against the force of the spring and "snaps" into place when the shaft aligns with the mounting hole in the frame member. This method makes assembly of the conveyor much simpler and facilitates the replacement of rollers when they become worn or defective.
Several attempts have been made in the past to eliminate through-shafts in the roller. In place of a single thru-shaft, separate stub shafts have been used to support opposing ends of the conveyor roller. Typically, these stub shafts are bolted to the conveyor frame before the frame is assembled. The conveyor roller is then inserted over the stub shaft as the frame is locked together to create a final assembly. This method of mounting rollers in conveyors also makes assembly difficult. Moreover, this method essentially precludes prefabrication of the conveyor frame.
Accordingly, there is a need for a new method for mounting conveyor rollers in a frame which does not rely on a through-shaft extending through the roller, allows prefabrication of the conveyor frame, and facilitates ease of assembly.