This invention relates to an improved beam of the type used in the construction of pallet racks and similar heavy-duty, load-bearing frames.
A typical pallet rack comprises a frame made of vertical posts which are interconnected by horizontal beams. Rigid slats or sheets may be positioned upon opposing beams to form shelves. Alternatively, the beams may be used alone like shelves. Horizontal platforms or pallets, loaded with articles to be stored, are positioned upon the opposed beams or the slats or sheets spanning the beams, where they are used. In essence, the rack is an open shelving arrangement.
In heavy-duty pallet racks or similar types of frames which are utilized to support heavy weights, the beams which extend horizontally between the corner posts and other parts of the frame, are made of sheet metal formed into tubes. These tubes are generally of a square or rectangular cross-section. One type of tubular beam, which is relevant to this invention, is made of a pair of roll-formed, open channels which are telescopically interfitted and secured together to provide the tubular shape. Here, one of the channels is formed with its legs more widely spaced apart then the other channel. The channel bases are arranged vertically and the legs horizontally. The channel with the closer legs is fitted between the wider legs of the one channel. Sometimes bent interfitting ribs and grooves are formed in the channel legs to mechanically hold them together. Then, the interfitted channels are welded together along their lengths to form a rigid tube.
The beam that is formed of the two interfitted channels is strong enough and rigid enough, assuming the use of proper dimensions and thicknesses of the metal, to support heavy weights. Thus, heavily loaded pallets may be rested upon a pair of parallel, spaced apart beams that are secured at their ends to upright posts.
These fabricated beams are relatively expensive to manufacture because of the need to weld the channels together. Typical welding, e.g., spot welding or MIG welding or the like, whether manually performed or performed in automatic machinery, takes considerable time and relatively expensive equipment. However, other means for rigidly and permanently interconnecting the two channels have not been satisfactory. Thus, the invention of this application is concerned with improving the two channel-type, tubular beam construction by reducing the time and equipment needed for fabricating the beam while at the same time producing a beam which is proportionately stronger than a corresponding prior-type welded beam.