Патент USA US2130983код для вставки
Sept. 20, 1938. W. KQHLER GRINDING MILL Filed April 5, 1954 ‘2,130,983 Patented Sept. 20, 1938 . ‘ i UNITED STATES PATENT OFFICE 2,130,983 GRINDING MILL Willy Kohler, Neckarhausen/Ladenburg-on-the Ne'ckar, Germany, assignor to Joseph Voegle V A. G., Mannheim, Germany Application April 5, 1934, Serial No. 719,177 - In Germany April 10, 1933 2 Claims. This invention relates to improvements in wet grinding mills in which the material to be ground passes between several smooth surfaced rolls in the form of a paste or thick ?uid. After each 5y; grinding stage the material under treatment is freed or liberated into a collecting space from which it passes to the next grinding stage. Even such repeated grinding and loosening of the material is not found to be adequate to ensure unilil'. formly ?ne grinding on the one hand and on the other hand this method of treatment fails to liberate undesirable volatile constituents which impart say, a disagreeable odour to the product. ' (01. 83-12) ranged to accommodate the material under treat ment in the various stages of the series of grind ing operations, which are shown as carried out by three grinding rolls b, c and g with smooth cy lindrical surfaces. The rolls are in any usual 5“ manner held in contact under pressure and ro tate with different surface speeds. The roll I) is supported wholly Within the hopper a whilst the roll 0 forms part of one side wall of the hopper and the roll 9 forms the base of the hopper. The 10. sloping sides of the hopper walls together with the rolls b and 0 form the collecting chambers for the material which, although in the form of These second mentioned considerations apply in 15; cases such as the ?ne grinding of chocolate and cocoa beans, so that in many such cases it is'necessary to pass the material through a separate stirring process which ventilates the material and enables the volatile constituents to pass off. 20 The object of the present invention is to enable a very high degree of uniform ?neness to be obtained in the product from such grinding mills and also in connection with this grinding operation at the same time to free the material of un25 desirably smelling constituents all in a single pass a paste or thick ?uid must be considered as in the coarse state relatively to the ?ne state of 15 the ?nished product. The coarse product is shown at k. The ?rst stage of the grinding takes place between the rolls 1) and c where the sur face of one of the rolls moves at a greater speed than the surface of the other so as to give a 20 rubbing or grinding action. After leaving the grinding point, the surfaces of both rolls are cleaned by passing scrapers d and e which may, if desired be arranged so that their pressure on the roll surface may be adjusted from outside. 25 through the machine. The invention consists of a grinding mill having a plurality of rolls forming a succession of grinding pairs through which the material is 30 passed in series with collecting chambers for the material interposed between each grinding stage and which is characterized by the provision of stirring mechanism in the collecting chamber between any grinding pair and the next following pair in the series. The effect of the interposition of this stirring mechanism is to subject the material which has just left or been liberated from one grinding pair to a mixing and breaking up operation which loosens the ?ne particles and liberates any undesirable volatile constituents and at the same time this loosening has the effect of increasing the grinding or comminuting action at the next following grinding pair. The invention is illustrated in the .accompanying drawing by way of illustration in a diagrammatic fashion, it being evident that the details of the grinding and stirring mechanism form no important feature of this invention and may be varied in a number of ways to suit different purposes and materials under treatment. The dia- This action loosens the material from the roll sur faces but does not break up the smaller cakes or clumps of material. The material 1‘ so loosened is in a ?ner state of comminution than the material 1c in the hopper compartment in front of the grinding pairb and 0. It will be understood that the side walls of the hopper a are arranged so close to the rolls 0 and 9 that none of the material can escape. The provision of the above described loosening means, that is scrapers d and e on the roller pairs 0 and b is known, but in accordance with this invention a stirring device 2' is provided in the collecting chamber for the material 1‘ which has been loosened or scraped from the roll surfaces by the scrapers d and e and this stirrer further breaks up or loosens the powder or paste and brings it to a more uniformly thick liquid con sistency free of lumps or cakes before the mate rial f passes to the grinding stage between the pair of rolls 0 and g. This active stirring operation thus ensures that the small solid particles are relatively dis placed and separated to open them up to the maximum grinding action at the next following stage. If the material, as is frequently the case, gram shows a form of the invention in cross section. has been squeezed into the form of ?akes or scales these are brought by the stirrer into a 35 40 - 45 50 In carrying the invention into effect according 55 to the form illustrated, a single hopper a is ar- 30 35 40 45 50 position throughout the mass which is in the great majority of cases either at right angles or 55 2,130,983 2 . at some inclined angle to the opening between t the rolls of the next following grinding pair, whereas in former designs these ?akes entered the second grinding pair more generally in a tangential path. In this way it is possible by means'of this invention to decrease the pressure between the second pair of grinding rolls and in fact this pressure does not require to be materially greater than that between the ?rst‘pa‘ir. The 10 comminution effected is nevertheless much great-v er owing to the fact that the pressure is applied to the ?akes more or less always in an “end on”, ' position. The power consumption of the mill is thereby reduced. 15 What I claim is: 3_ ' ' ' faces of the said rolls and the adjacent chamber walls, and rotatable about an axis generally par allel to the axes of said rolls, said stirrer having a surface movable into proximity to said grinding rolls to feed the material passed between the ?rst grinding pair towards the bite of the second grinding pair.‘ 7 ' 2. A grinding mill for use in grinding generally ?uid material possessing undesirable volatile con stituents, said mill including three grinding rolls 10 cooperating to provide ‘two grinding pairs be tween which all of the material is passed in suc cession, the adjacent surfaces of the rolls con stituting the ?rst grinding pair travelling in the same direction, an open chamber in constant 15 1. A grinding mill for use in grinding gener communication with the atmosphere, said cham ally ?uid material possessingLundesirable vola+ ber being disposed in proximity to the discharge tile constituents, said mill including three grind-r ’. from the ?rst grinding pair, and being also dis- ~ ing rolls cooperating to provide two grinding posed in proximity to the intake of the second grinding pair, and a rotary stirrer for agitating 20 20 pairs between which all of the material‘is passed in succession, an open chamber in constant com the material in said open chamber and for re munication with the atmosphere, said chamber leasing said undesirable volatile constituents therefrom, said stirrer being disposed within said being disposed in proximity to the discharge from the ?rst grinding pair and being also dis 25 posed in proximity to the intake. of the second grinding pair, a generally stationary scraper op eratively bearing against oneof the rolls consti~ tuting the ?rst grinding pair andv arranged to scrape material therefrom and into said open 30 chamber, said scraper being transversely spaced from a wall ‘of said open chamber to permit the undesirable volatile constituents of the material in said chamber tov escape between said scraper and said chamber wall to the atmosphere, and a 351 rotary stirrer separate from said scraper for agi tating the material in ‘said open " chamber and for releasing said undesirable volatile constituents therefrom, said stirrer being disposed-within said 7 chamber, and transversely'spaced‘from the sur chamber and transversely spaced from the sur faces of the said rolls and the adjacent chamber 25 walls, and rotatable about an axis generally par allel to the axes of said rolls, the direction of ro tation of said stirrer beingopposite the direction of rotation of the ?rst grinding roll, and said stirrer having a surface movable into proximity 30 to said grinding rolls to feedrthe material passed between the ?rst grinding pair towards the bite of the second grinding pair, whereby the material discharged from between the ?rst grinding pair and entering said open chamber will be moved by 35 said stirrer towards the bite of the second grind ing pair along a path other than the shortest route; , WILLY KoHLER.