US400619A - winklee - Google Patents

Description

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vvMETHOD 0F SEFSIIIN'G. GRANULAR MATERIAL. No. 100,619.V Patented Apr. 2, 1889.

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l METHOD 0F SIFTING GRANULAB, MATERIAL. No. 400,619.

Patented Apr.2, 1889.

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Patented Apr. 2, 1889.

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Patented Apr. 2, 1889.

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FRIEDRICH GEORG WINKLER, OFZSOHOPPAU, SAXONY, GERMANY, ASSIGNOR TO ROBERT E. LESTER, OF NEWYORK, N. Y.

METHOD OF SIFTING GRANULAR MATERIAL.

SPECIFICATION forming part of Letters Patent No. 400,619, dated April 2, v1889.

No. 40,357, and October 22, 1886, No. 39,709.

Toa/ZZ whom t may concern:

Be it known that Iv, FRIEDRICH GEORG. WINKLER, a subject of the King of Saxony, residing at Zschoppau, in the Kingdom of Saxony, Germany, have4 invented new and useful Improvements in the Method of Sifting Flour orl other Granular Materials through Sieves of Hollow Cylindrical Form, (for which I have obtained Letters Patent from the Geryman Empire, No. 38,576, dated April 2, 1886,

No. 39,709, dated October 22, 1886,v and No. 40,357, dated July 8, 1886,) of which the following is a specification.

This invention relates to a method of sifting flour or other granular material through a bolting-cloth forming the curved surface of a drum, which consists in progressively subjecting the meal or other substance deposited upon the inner surface of the bolting-cloth to the action, alternately, of radially-outward jets or currents of air of comparatively small area in cross-section, but of considerable pressure, and radially-inward currents of air of larger area in cross-section, but of relatively lower pressure, whereby the finervparticles of the material present are by the cur-v rents of high pressure blown ou tward through the meshes of the bolting-cloth, and immediately afterward any coarser particles which may have lodged against the inner surface 'of the bolting-cloth are driven radially inward therefrom by the inward movement of the currents of air of low pressure.

The described wave lmotions of air arepropagated progressively around the entire circumference of the drum by means of internal rotating fans, the spaces between which are closed at the ends. In front of the advancing side of each fan the air is compressed, and a portion of it, which is expelled from the area of compression in an outward direction, performs the function of blowing the finer particles of the material operated upon through the rmeshes of the cloth. To promote the performance of this function, a concentric system of detlecting bars arranged lengthwise of the drum is interposed between the inner surface of the bolting-cloth and the path of motion ofthe fans, whereby the outwardly-pressadjacent portion of `the boltingcloth, which is thus cleared of obstruction in time for the action of the next following outward current ol' air. The materials thus dislodged from the inner surface of the bolting-cloth are arrested in their'inward movement by the dei'lecting-bars, and before they have time to l Application filed August 24, 1887. Serial N o. 247,765. (No model.) Patented in Germany April 2, 1886, No. 38,576, July 8, 1886,

make their way entirely through the spaces between the bars are caught and again thrown outward by the outward current of air generated by the next following fan-stroke.

The presence of longitudinal deectingbars prevents the establishment of a circular current of air around the inside of the sieve or bolting-cloth, which would otherwise be established by the rotation of the fans, and which by carrying with it portions of .the material lying against the surface of the boltin gcloth would create an obstacle to radial currents through the bolting-cloth in either dii rection. The detlecting-bars, therefore, are

useful in two respects: They prevent the ma-l terial operated upon from acquiring a circular movement around the inner surface of the Asieve or boltiug-cloth, and they deiiect the outgoingcurrents of air radially toward the sieve or bolting-cloth, and thus cause-such currents to blow or press the material operated upon directly through the meshes of the sieve or bolting-cloth. l

The fans employed maybe almost infinitely varied in the forms of their cross-section; but in all cases they extend longitudinally entirely across the rotating structure, and either terminate at their ends, respectively, in the opposed faces of parallel disks affixed to the fan-shaft or they terminate in close proximity to the opposed faces of some other parallel walls, so that in any case the spaces between the fans are closed at the ends, and thus when a partial vacuum is established in the said spaces by the radially-outward ejection therefrom of the compressed air in front of the advancing fan-surfaces the only path for the return of air to supply such vacuum will be an inward path at the periphery of the rotating structure in the rear of the advancing fan-surfaces. It will thus be seen that the rotating fan-structure imparts to the air at its periphery a series of outward and inward vibratory movements, and is thus a wave-generator propagating a wave of air in a circular path.

Apparatus suitable for carrying out the described method of sifting in the manufacture of fiour is represented in the accompanying drawings. This apparatus is here referred to for illustration merely, and the mechanical features of novelty which it contains are made the subject of another application for a patent, serially numbered 291,549, filed November 22, 1888.

The drawings represent a flour-bolt, and

are as follows:

Figure 1 is a central longitudinal section exhibiting a portion of the fan in elevation and showing a pulley for rotating the cylindrical sieve. Fig. 2 is a transverse vertical section taken through the plane indicated by the dotted line 0c on Fig. 1. Fig. 3 is a longitudinal horizontal section taken through the plane indicated by the line y y on Fig. 2, but showing intermediate gearing for rotating the cylindrical sieve. Fig. 4 is an end elevation. Fig. 5 is a transverse vertical section taken through the plane indicated by the line zz on Fig. 3. Figs. 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, and 17 are transverse sections of various forms of rotating wave-generating fans.

The drawings represent a bolting-chest, A, to the opposite ends of which are affixed the gear-frames a a. Within the bolting-chest is a preferably-rotating drum, the curved surface of which is principally composed of a sieve or bolting-eloth, B. Within the sievedrum is a rotating cylindrically-arranged system of defiecting-bars, C. Vithin the cylindrically-arranged system of defiecting-bars is a rapidly-rotating wave-generator consisting of fans D D, fastened at their opposite ends, respectively, to the two heads or disks D D', which are respectively secured to the flanges d d of a hollow shaft, d, keyed to the rapidly-revolving shaft E. The shaft E is journaled at its opposite ends, respectively, in the boxes e e', carried in the hollow bosses a a, cast on the ends of' the gear-frames a a. The heads b b of' the sieve are provided, respectively, with the hollow hubs b b2, journaled in the boxes b3 b4, which derive their support `from the gear-frames, respectively. The system of defiecting-bars C is supported upon the peripheries of two parallel disks, C C2, which are provided, respectively, with the hollow hubs C3 C4. The hollow hubs C3 C4 extend through the hubs b b2 and are journaled in the boxes C5 C, carried upon the gear-frames. The hollow hubs b b2 are of sufficiently large diameter to afford considerable clearance for the hollow hubs C3 C, which in turn are made of large enough diameter to afford ample clearance for the swiftrunning shaft E. 1t is not absolutely essential that the sieve-drum should rotate; but it is desirable in order to secure the uniform wear of the bolting-cloth. The shaft E is provided at one end with the fast and loose pulleys E and E2 for engaging the belt which drives the wave-generator. The pulley C7, affixed to the hollow hub C4, drives the rotating system of deflecting-bars, and a spur-wheel, C8, affixed to the hub C3, engages and drives a pinion, C, affixed to a counter-shaft, C10, provided upon its inner end with the spurwheel C, which engages the gear C12, affixed to the hub b of the sieve-drum, as shown in Figs. 3 and 4.

In practice the sieve-drum will be driven at the rate of from, say, twenty to thirty revolutions per minute, the system of deflecting bars at from one hundred to two hundred revolutions per minute, and the wave-generator at from five hundred to eight hundred ,revolutions per minute.

The meal or other material to be sifted is introduced into the feedchute F, through which it falls into the interior of the hollow hub b2, from which it is conveyed, by means of the spiral screw-blade f, affixed to the hub C4, into the space between the head b of the sieve-drum and the disk C2, down which it falls to the interior surface of the boltingcloth, A blade, C13, affixed to and extending spirally around the exterior surface of the system of the defiecting-bars, serves to gradually move the meal longitudinally along the inner surface of the bolting-cloth. The flour sifts through the meshes of the bolting-cloth and is carried by means of a screw-conveyer, G, to the flour-discharge chute G. The bran gradually moved along the interior surface of the bolting-cloth finally escapes through the openings B in the head b into the bran-discharge chute H.

As the sifting operation is performed merely by the vibratory motions of the air induced by the wave-generator, the fiour is discharged through the fiour-chute G and the bran is discharged through the bran-chute H without any accompanying outward currents of air. The total quantity of air in the bolting-chest remains unchanged, and the flour and bran are discharged therefrom simply by their own gravity.

The sifting effect will be best promoted by stretching the bolting-cloth tightly, so that it will not participate in the vibratory movements of the air induced by the wave-generator. The wave-generator illustrated in Fig. 2 generates two waves. The compressed air in front of the advancing fan-surfaces I and IOO IIO

J is Idriven outward, as'indicated by the longer arrows, from comparatively small portions of the periphery of the wave-generator, and air much greater than the pressure of the inward current. By enlarging-the diameter of the wave-generator a larger number of fans may beemployed, and thus a larger number of waves maybe simultaneously generated. Or-

dinarily, however, it will be sufficient to employ a double wave-generator-that is, a generator with two fans generating two waves simultaneously, respectively, on opposite-sides of the generator.

Wave-generators, so far as regards the forms and positions o f their fans, are suscep- -tible of almost infinite variation. Examples of a few of the possible modifications are represented in cross-section in Figs. 6 to 17,

.i both inclusive.` ,Each of the double wavegenerators consists of two parallel disks affixed to a rotating shaft and united to each other by longitudinal partitions which Vin some `cases are fiat, in others curved, and which in some cases extend from the shaft outward toward the periphery, and in othercases are united alongy one or both of their longitudinal edges. tion of rotation isindicated by a long concentrically-curved arrow, the areas of rarefaction are approximately indicated by net-works of shade-lines, and the approximate directions of the induced vibratory air-currents are indicated by the short arrows in eachfigure.

YIt will be seen that'in all the forms of wavegenerators shown there are established cells or spaces extendinglongitudinally across thel waVe-generatonwhich cells are open only toward k,the periphery, and henceA that in all r cases the partial vacua established in parts .V p litude as dstingushed from centrifugal fans such as heretofore known ,which operate to produce a blast of air by constantly ej ecting from the periphery air which is drawn in at the ends of Y the Vrotating structure. It will hence be seen that the essential characteristic of what is herein termed a wave-generator is that the longitudinal. spaces or Ycells with which it is provided, irrespective oftheir shape in cross- In all these figures the direcsection, shall be open only toward the periphery of the rotating structure.

- It is to be remarked that as a rule the amplitude of the vair-vibrations will increase or decrease accordingly as'the speed of rota y:ion of the wave-generator is increased or decreased, and it is also to be observed that in wave-generators in which the fans are composed simply of radial or nearly radial partitions, as illustrated in Figs. 6, 7, and 8, there will be a tendency of the air expelled from the forward side of the fan to turn immediately over the outer edge of the fan and inward into the space behind the advancing fan. This difficulty, however, can be overcome by increasing the speed Vof .rotation of the generator. It may also be overcome .by the employment of a' group of fanblades in comparatively close proximity to each other, as illustrated in Figs. l() and ll, or by the employment of a concentricallycurved shield having its forward edge connected with the outer edge of the fan-blade and having its rear edge connectedl with the outer edge of the next adjoining partition, as illustrated in Fig. lll. By either of these expedients the area of rarefaction is removed so far to the rear of the area of extreme condensationthat the current of compressed air is ejected against the sieve without loss of pressure. To such an extent is this the case that to produce outward currents of air of given pressure the form of generator illustrated in Fig. l will require to be rotated at from two and a half to three times the speed of the generator illustrated in Fig. ll. f

In practice a wave-generator of twenty-two inches diameter having the form illustrated in Fig. 2 has been found to be peculiarly effective when used in a scalper and rotated at from three hundred to seven hundred revolutions per minute. It will be understood that in the scalper the flour of relatively high specific gravity is separated from the bran, which is of relatively low specific gravity.

When the wavegenerator illustrated in Fig. 2 is employed in machines for sifting iiour, it is rotated at a speed of from one thousand to fifteen hundred revolutions per min-- ute.

These examples are given merely for the purpose of practical illustration. l

The principles governing the construction of wave-generators are those which have been described. The principle to be observed in operating them consists in so regulating their speed of rotation that the outward current ejected through a comparatively small area of the sieve will have j ust sufficient pressure to force the finer material through the meshes, so that at the same time t-he quantity of air required to supply the place of that thusej ected will enter the generator through a comparatively large area of the sieve, and hence at such low pressure on the exterior of this comparatively large area of the sieve thatV there will IOO IIO

be no danger of causing the sifting material to adhere to and clog the exterior of this portion of the sieve. It Will thus be seen that this invention is not limited to any particular` arrangement of fans in a Wave-generator, but is present in any cylindrical sieve in which there is employed a Wave-generator having the essential characteristics of construction and mode of operation herein described.

In the drawings the cylindrically-arranged system of defiecting-bars, which, for the sake of brevity, may be called the deliectinggrate, is represented as composed of angle bars or slats.

It is to be understood that the invention is not limited to the usc of a detlecting-grate composed of angle-bars such as shown, but is equally present iu a sifter in which there is employed a deiiecting-grate composed of bars Which are parallel or approximately parallel with the axis of the rotating structure, irrespective of the shape of the bars in cross-section. The presence ot these bars, as has been explained, prevents the establishment of circular currents of air immediately within the cylindrical sieve and insures the deiiection of the currents of air ejected by the rotating fans.

Instead of employing intermediate gearing, as illustrated in Figs. 3 and 4, for transmitting motion to rotate the sieve from the shaft C4 ot' the rotating defiecting-grate, the hollenv hub Z9 of lthe disk I) of the rotating sieve may be provided with the pulley B2, and may thus be driven by the belt independently of the r0- tating deiiecting-grate.

It will be seen that by throwing the belt olf of the pulley 2 the sieve will remain stationary, and it will also be seen that the dedecting-grate may be rotated or not, according to whether the belt is applied to the driving-pulley CT. Thus either or both the dcflectinggrate and the sieve may be rotated or not, as may be desired.

lVhat is claimed as the invention is- The herein-described method of siftin g iour or other granular material through a sieve or I )olting-cloth forming the curved Wall of a cylindrical drum, which consists in the subjection of all parts of such sieve or boltingcloth, and hence the subjection of all portionsl of the granular material contained within the sieve or bolting-cloth, successively to the influence alternately of a relatively-strong current of air moving transversely outward through a prescribed area of the sieve and a relatively-weak current of air moving transversely inward through a larger area of the sieve.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

FRIEDRICH GEORG IVINKLER.

\Vitnesses:

H. R. BIGELoW, G. HTSMANN.

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