The present invention relates to a separating apparatus. More particularly this invention concerns a table separator for particulate material such as rice, oats, rye, corn and the like.
It is known to separate different sizes of particulate material, such as hulled rice grains from unhulled rice grains, by means of a separating table which is agitated. The table is normally tipped to the horizontal and the unseparated material is charged onto the table at the upper side. In such table separators the particles of said particulate material will be separated, e.g. unhulled rice grains from hulled rice grains, bei means of a plurality of separating chambers positioned on the said table and provided with zigg-zagged baffles, and in which the material is separated into a plurality of fractions by taking advantage of the way in which the material particles ricochet.
In such arrangements the throughput, that is the massive material separated per unit of time, is directly proportional to the rate of vibration of the table and the length of the stroke of the table each time it vibrates. Such machines invariably vibrate so greatly that they must be extremely ruggedly built and solidly anchored so that they do not literally shake themselves to pieces. Thus it is virtually impossible to mount such machines on anything but the ground floor, which must normally be reinforced in any case. This constraint is disadvantageous in many plant setups where the material flow is ideally from upper floors toward lower floors, so that after separating in such plants the material must be transported up before it can be processed. It is also noted that there is considerable energy wasted by such machines in vibrating their entire frames and all of the structure surrounding them.
It has been suggested to provide a pair of superposed screens each of which is provided with a rack extending parallel to the rack of the other screen and having teeth directed toward the teeth of the other screen. A gear wheel is provided between and in mesh with both of these racks and is mounted on the end of an oscillating arm driven from a crank on a motor that is fixed beneath the arrangement. Thus the one screen is moved in one direction as the other screen is moved in the opposite direction so that a limited amount of force equilization is obtained. Nonetheless the motor has considerable throw, so that the machine still vibrates considerably and must be extremely ruggedly built and securely mounted as described above.