US228001A - Roller grinding-mill - Google Patents

Description

J. STEVENS. Roller Grinding Mill.

Patented May 25,

N. PETERSrPHOTQUTNOGRAFHER, WAISNYNGYIDN. D. C

UNITED STATES PATENT QFFICE JOHN STEVENS, OF NEENAH, WISCONSIN.

ROLLER GRINDING-MILL.

SPECIFICATION forming part of Letters Patent No. 228,001, dated May 25, 1880.

Application filed February 13, 1878.

To all whom it may concern:

Be it known that I, JOHN STEvENs, of Neenah, in the county of Winnebago and State of Wisconsin, have invented certain new and useful Improvements in Grinding-Mills and in the Process of Reducing Grain to Flour, of which the following is a specification.

My invention relates to that class of grinding-mills known as roller-mills, wherein two or more rolls or cylinders revolving at diiferent peripheral rates of speed work against each other; and it consists in forming the rolls with parallel grooves having rounded dividing-ribs trending lengthwise of the rolls; in laying the ribs in such direction upon each roll that they cross each other upon the contiguous surfaces, and in employing, in the process of reducing grain to flour, a series of sets of such rolls graded in respect to fineness 01' number of grooves to the inch, with intermediate bolts, the several sets acting in sue cession of grade.

In the drawings, Figures 1 and 2 are, respectively, an end and a plan view of a pair of rolls provided With a dress according to my invention. Fig. 3 is a diagram representing sets of graded rolls and bolts arranged according to my invention.

The object constantly aimed at in the process of reducing wheat to flour is to increase the proportion of middlings and pure flour, and to leave the bran and germ in a condition most favorable to their eflectual and complete separation from the flour-forming particles. Smooth-surfaced rolls flatten the germ and allow the bran to pass in a coarse unpulverized state, and tothis extent accomplish the object; but they also cause the middlings to cake or form into flakes or thin disks, that will not pass through the meshes of the bolt, and therefore are in the end unsatisfactory. Grooved rolls having sharp edged intermediate ribs cut or tear the bran and germ into such fine particles that a large proportion will pass through ordinary bolting cloth and inevitably appear in the middlings and flour, from which they can with great difficulty be removed.

My invention is designed to overcome these objections and to produce a machine in which the starch and gluten of the berry shall be properly pulverized without caking, while the tenacious portions, constituting the husk and germ, shall pass through in a flattened or flaky condition without being much comminuted, thereby greatly increasing the middlings and improving the quality of flour.

lteferrin g to the drawings, the rolls a 1), constructed preferably of metal, are placed side by, side in the same horizontal plane, and geared to revolve at different peripheral speeds. Each is provided with spiral grooves running in the same direction and laid near together, the dividing-ribs between these grooves being rounded, as shown more particularly in that portion of Fig. 1 inclosed between brackets l 1. These rolls operate in a manner superior to the smooth-surfaced and sharp-ribbed rolls,.

heretofore known, for, unlike smooth rolls, they do not form the middlings into disks or flakes which require various and intricate subsequent operations to reduce them to flour, nor do they cut or tear the bran and germ into fine pieces or particles, as is the case with sharpribbed rolls; but while pulverizing the starch and gluten, they simply bruise and rub the bran and germ, bringing them to and leaving them in a form which insures their passage over the tail of the bolt, and therefore their elimination from the middlings and flour.

Since the grooves and ribs are laid in the same direction on both rolls, they will cross each other on the contiguous surfaces and cannot intermesh. The rolls can therefore be run in peripheral contact without injury to the dress or face, and heating of the flour is reduced to a minimum, as contact with the grinding-surface is momentary or instantaneous.

The dress may vary in number of grooves to the linear inch, as will hereinafter appear, and one set of rolls capable of suitable adjustments will be sufficient for general work. I think it beneficial, however, to employaseries of sets of rolls graded in respect to fineness of dress. The arrangement may be as shown in Fig. 3. The numerals 1 2 3 4, respectively, indicate separate sets of rolls. Each set is composed of two rolls geared together so as to revolve with differential motion as to their peripheries, and both rolls of each set have spiral grooves running in the same direction, from left to right.

The grooves of rolls A A in the set No. l

are assumed to number about twenty to the linear inch, measured circumferentially on the periphery; the grooves of the rolls B B in the set No. 2 to number about twenty-three to the inch of the rolls 0 O, in set No. 3, to number about twenty-eight, and of the finishing-rolls D D, in the fourth set, to range from thirty to thirty-two-that is to say, the range of gradation I have chosen to illustrate my invention is from twenty to thirty-two; but the limit admits of more or less variation in either direction toward or from a dress numbering about seven or eight grooves to the linear inch.

With wheat and other cereals it will be inadvisable to have more than fifteen grooves to the inch, at least in the first pair of rolls, and the number of grooves in any set should never be so great as to cause the ribs to lose their distinctively rounded character or become so pointed as to cut the bran.

The practical operation is as follows: The Wheat to be converted into flour is fed into a hopper, (not shown in the drawings,) and passes thence between the first set of rolls, A A, the product consisting of cracked or partly-crushed wheat, and a considerable quantity of flour is delivered to a bolt, F, and the coarser grades and tailings from the bolting operation are carried to the neXt pair of rolls, B B, which have finer grooves than rolls A A. The product of rolls B B is, in turn, passed through bolt G, and so the operation goes on by alternately cracking or grinding and bolting, through the series of machines until the desired product has been thoroughly separated from the bran.

I claim as my invention- 1. In a grinding-mill, the combination of rolls geared to revolve at different peripheral rates of speed and having a dress composed of parallel grooves with rounded dividing-ribs trendinglengthwise of the rolls.

2. In a grinding-mill, the combination of rolls geared to revolve at different peripheral rates of speed and having a dress composed of parallel grooves with rounded dividingribs laid so as to cross each other on the con- -tiguous surfaces of the rolls.

3. In a grinding-mill, the combination ,of rolls geared to revolve at different peripheral rates of speed and having a dress composed of parallel spiral grooves with rounded dividingribs running in the same direction on each roll.

4. The combination of a series of sets of rolls provided with the grooved dress herein described, and graded in respect to fineness of dress, with. bolts intermediate between each set and the succeeding set of rolls.

5. The process of reducing grain to flour, consisting in passing it through a series of sets of rolls graded in respect to fineness of dress, and through bolts intermediate between each set and the succeeding set of rolls.

The above specification of my invention signed by me this 13th day of February, 1878.

JOHN STEVENS.

Witnesses:

SoLoN O. KEMON, OHAs. A. PETTIT.

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