Screw Conveyors
VOL. 20 NO. 2Gem Equipment's product line has always included screw conveyors. Design and manufacturing technology used for screw conveyors is applicable to other equipment utilized in food processing plants. To produce an auger blancher, manufacture a large screw conveyor, add hot water and provide a method to get the product out of the water at the discharge end. Rotary blanchers use an auger wrapped with perforated metal to convey product through the blanching medium, which is usually water. Paddle mixers and ribbon mixers are screw conveyors with different styles of rotors. Screw feeders and their close cousins, live auger bin bottoms, are examples of specialized use of screw conveyors. Gem Equipment manufactures all of the equipment mentioned above.
While Gem is capable of manufacturing augers, if lead time is adequate, most standard augers are now purchased from companies with high enough volume to justify specialized equipment to improve productivity. This company manufactures troughs, lids, ends, augers with specialized configuration; furnishes specialized welding and final assembly. Manufacturers of standard augers usually skip weld the flights to the center tube. Most food processing requires flights continuously welded to the center tube. For many applications, a neat wire feed weld is all that is necessary. For a higher level of sanitation either a heli-arc or a ground and polished wire feed weld will be used. Ground and polished welds are the most expensive, are usually the same finish as the flights and are required for many USDA applications.
One design of live bottom bin, manufactured by this company, utilizes one, or more, specialized augers. The most sophisticated bin bottoms are designed to pick up product uniformly across the bottom of the pile. This is accomplished by increasing pitch along the auger progressing from the infeed to the discharge end. In addition, unless a live bottom bin auger is very short, the auger center tube will have a cone shaped infeed section. The larger diameter center tube decreases the volume of product picked up at the infeed end, making it easier to design the auger to pickup product at a constant rate along its full length. In the early 1990's, Gem manufactured thirty-inch diameter, eighteen-foot long augers using this configuration, to gather product at the bottom of vertical potato preheaters.
One of the more interesting applications utilized a screw conveyor designed to thaw frozen product while it was being conveyed. Both the auger and the trough were double walled to accommodate circulation of hot water to furnish heat for the thawing process. Rotary couplings were used at each end of the auger to provide inlet and outlet connections for the hot water. This screw conveyor was fed by a tote dumper and pivoted horizontally about its infeed end so product could be fed to any one of several tanks. Perhaps the most unusual use of a screw conveyor by this company was for a spreading application too messy for a belt conveyor and with insufficient headroom for a bias feed shaker. Instead, an inclined screw conveyor with a bias discharge several feet long was used to distribute whole potatoes to a roll sizer. If you need screw conveyors, contact Gem