US826061A - Pulverizing-mill. - Google Patents

Description

G. L. PRATT.

PULVERIZING MILL. APPLICATION FILED AUG. 14, 1905.

PATENTED JULY 1'7, 1906.

2 SHEETSSHEET 1.

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PATENTED JULY 17; 1906.

G. LfPR-ATT. PULVERIZING MILL. APPLICATION FILED AUG. 14, 1905.

' 2 SHEETS-SHEET 2.

WITNESSES; I QM 1H: nonms rsrsns cu, WASHINGTON, a. c.

GEORGE LEWIS PRATT, OF ATLANTA, GEORGIA.

PULVERlZlNG-MILLi Specification of Letters Patent.

f Patented July 17, 1906.

Application filed August 14,1905. Serial No. 274,210.

To all whom, it may concern.-

Be it known that I, GEORGE LEWIS PRATT, a citizen of the United States, residing at Atlanta, in the county of Fulton and State of Georgia, have invented certain new and useful Improvements in Pulverizing-Mills; and I do hereby declare the following to' be a full, clear, and exact description of the invention,

such as will enable others skilled in the art to which it app ertains to make and use the same.

Much difficulty has been experienced in the past in securing from a centrifugal pulverizing-mill a product of sufficient fineness without the use of separating-screens surrounding the pulverizing-chamber of such fine mesh, and consequentlyso fragile, as to result in serious damage and wear and tear from the flying lumps or particles of the material deliv- %red to the interior of the pulverizing-cham- Among the more important objects, therefore, of my invention are, first, the peculiar arrangement of a fine or final separating-screen relative to an inner heavier or coarser protecting-screen and the inclination of both fine and coarse screens from the vertical line, whereby in operation the material passing the inner protecting-screen must necessarily fall upon the outer or finishing screen, thereby giving a gravity separation which must necessarily result in the passage of all or at least the major part of the sufficiently fine material through the outer or finishing screen without serious wear and tear which necessarily occur if the inner or protecting screen were not used; second, the peculiar formation or arrangement of a pulverizing-ring with relation to a pulverizing-roller and with reference to the screens surrounding the pulverizing-chamber, whereby the splash resulting from the contact of the pulverizingroller with the material lying along the inner surface of the pulverizing-ring will be practically parallel to the screens, thereby assisting to produce a gravity separation which could not otherwise be obtained; third, the peculiar arrangement of the revolving table carrying the roll-shafts and forming the upper housing of the pulverizing-chamber and the provision of strengthening-ribs placed underneath which table for subserving the dual function of supports and of creating a blastwheel effect, forcing a current of air against the screen which assists in the separation and the cleaning of the screens, openings at or near the center of the revolving table allowing the introduction of the material to be pulverized, said openings also permitting the ingress of air occasioned by the said blast effect; fourth, the provision of an additional housing above the top of the revolving table with openings at or near its center, so that any leakage or escape of dust from the pulverizing-chamber will be drawn back through the openings in the top of the revolving table.

With these objects in view and others the invention consists in the novel construction, combination, and arrangement of parts, as will be hereinafter fully described in the specification, illustrated in the drawings, and summed up in the claims.

In the accompanying drawings, Figure 1 is a vertical section through my improved pulverizing-machine. Fig. 2 is a horizontal section on line 1 1, and Fig. 3 is a horizontal section on line 2 2.

Referring to the drawings, the bed-plate or base A of the machine may be made of any desired shape, preferably circular, and is formed with a curved conical annular flange c connected with an outer curved annularv flange a by radial ribs 0/, which flange a with the bottom ai oonstitutes the pulverizing pan or receptacle for the incoming material. On the inner face of the pan a may be secured a conical pulverizing-ring B. Secured around an annular notch (1 in flange a is an annular drum or casing a. Legs or standards C are secured to base A and extend upward for a distance and then converge and are bolted to a head D. Bolted to the standards C is a spider E, which carries at its center the main bearing F, which bearing carries the main vertical shaft G. Preferably bolted between the ribs or spokes of spider E are segmental covers e which are provided with annular downward-projecting curved flanges e provided with annular notches to carry the annular casing a, an outer screen a and an inner screen a. The lower edge of the outer screen a is desirably carried by a conical flange a preferably forming part of the pulverizing member B, but in the drawings shown as separate and clamped thereto. The lower edge of the inside screen a is desirably carried by lugs or straps a, fixed at intervals to the flange at. These lugs are sufficiently separated from each other around the flange a to hold securely in position the bottom of the inner coarse screen a and at the same time not to prevent the passage of material I which has passed through screen a and has IIO been rejected by screen a back into the pulverizing-pan-that is, not to prevent it from falling out at the bottom between the two screens of and a over the edge of the pulverizing member B into the pan.

The main shaft G may be supported at its head 9 by various bearing-disks g g and g on the flanged bearing-lining g and is driven by gears H and H and pulley H At the lower end of shaft G is carried the revolving table J, which is provided on its under side with ribs J for the support of the trunnion-blocks K. The table is finished at its outside edge so that it will rotate very nearly adjacent to the segments a, as shown at j Near the center of revolving table J and immediately outside the hub are provided openings 3' and the segments e not reaching entirely to the center of the spider E. Openings 6 are formed through any or all of which and through the openings feed may be delivered to the machine and also through which comes in air drawn in by the fan action of the ribs J under table J. Car ried by ribs J and revolubly secured therebetween are trunnion-heads K, into which are secured shafts K, carrying revoluble rollers K The material to be pulverizedis fed into the machine through any suitable hopper, (not shown,) falls downward into the pulverizing-chamber, is caught by the rollers K or the plows h and brought out into contact with the pulverizing-ring B, where it is crushed or pulverized by the rolling action of the rollers K on ring B. Any material more or less finely pulverized is splashed up onto the surface of screen a, as is also other material thrown thereon by the action of all the inner revolving parts. Any of such material, whether splashed from the ring or thrown by the revolving parts, which is of sufficient fineness passes through the coarse screen a and falls upon outer screen a where a further separation takes place of any degree of fineness desired, determined only by the fineness of mesh of screen a". Any material rejected by screen a immediately falls back to be again caught between the surface of the rollers K and the inner surface of ring B for further pulverization. Similarly material which has passed through screen a, but has been rejected by screen a falls between the two screens and in over the edge of the pulverizing-ring B to be similarly further pulverized. Material of sufficient fineness having passed through both screens a and a is prevented from escaping by the cylindrical casing a and falls therefrom down through the spaces a, formed by the ribs a into a suitable hopper or conveyer underneath the machine. Similarly air drawn into the machine by the fan action of the revolving parts passes through the screens and down through the same channels a, from whence it can be delivered in any direction desired.

It will be noticed that a small crack (shown at 9' must necessarily exist between revolving table J and the downward-projecting flanges e of the segments 6 Also there must be some crack around the trunnion-heads K where they fit into and are attached between the ribs J of revolving table J. (See Figs. 1 and 2.) If, therefore, no additional housing such as is formed by these segments 6 were provided above the top of the revolving table, escape of dust through the cracks mentioned must necessarily be free to the outside air, and similarly would this be the case if there were any openings in this housing other than those 0'', (shown at or about the center of the segmental covers 6 The housing e above the top of the horizontal table J therefore subserves the very important function of collecting and reintroducing at the center any flying particles escaping from around the outside edge of the revolving table. The peculiar construction of the parts permits of absolute closing of the pulverizing-chamber except at or near the center, through which there must necessarily be a suck of air rather than an outblow. It will further be noticed that a distinct advantage is gained by placing the lower or driving pinion H below the main gear H, this advantage being twofoldfirst, the gear is between the bearings, and, second, the belt leading away from pulley H the lower side of which is preferably the pulling side, brings all of the wear on the horizontal bearing in this shaft in one direction, and the inner bearing of this horizontal shaft acting as the fulcrum and the upper gear H as the work, similarly the strain on this inner bearing must necessarily be in the same direction as that on the outer bearing. Therefore the alinement isalways perfectly maintained.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a pulverizing-machine, a practicallyinclosed pulverizing-chamber formed at the bottom by a pulverizing-pan, at the sides by a surrounding drum or casin and at the top by a housing open only at t e center; a revolving table supported beneath the housin and carrying roller-supporting shafts, said table being provided with openings at the center; and an outside and an inner screening-surface disposed about the pulverizingpan, and against which there is a fan action induced by the roller-shafts, when the machine is in operation.

2. In a pulverizing-machine,-a practicallyinclosed pulverizing-chamber formed at the bottom by a pulverizing-pan, at the sides by a surrounding drum or casin and at the top by a housing open only at t e center; a revolving table supported beneath the housing and carrying roller-supporting shafts and having strengthening-ribs underneath, said table also being provided with openings at the center; and an outside and an inner screening-surface disposed about the pulverizing-pan and against which there is a fan action induced by the ribs and roller-shafts, when the machine is in operation.

3. In a pulverizing-maohine, a practicallyinclosed pulverizing-chamber formed at the bottom by a pulverizing-pan', at the sides by a surrounding drum or casing, and at the top by a housing open only at the center; a revolving table sup orted beneath the housing and carrying r0 ler-supporting shafts and having strengthening-ribs underneath, said table also being provided with openings at the center; and an outside and an inner screening-surface disposed about the pulverizing-pan and in close proximity one to the other, and against whic there is a fan action induced by the ribs and roller-shafts, when the machine is in operation.

4. In a pulverizing-machine, a practicallyinclosed pulverizing-chamber formed at the bottom by a pulverizing-pan, at the sides by a surrounding drum or casing, and at the top by a housing open only at the center; a revolving table supported beneath the housing and carrying roller-supporting shafts and having strengthening-ribs underneath, said table also being provided with openings at the center, and an outside, and an inside, heavier and coarser screening-surface disposed about the pulverizing-pan and in close proximity one to the other, and against which there is a fan action induced by the ribs and roller-shafts, when the machine is in operation.

5. In a pulverizing-machine, a practicallyinclosed pulverizing-chamber formed at the bottom by a pulverizing-pan, at the sides by a surrounding drum or casing, and at the top by a housing open only at the center; arevolving table sup orted beneath the housing and carrying ro her-supporting shafts and having strengthening-ribs underneath, said table also being provided with openings at the center, and an outside and an inner screening-surface slantingly disposed about the pulverizing-pan and in close proximity one to the other, whereby there is a gravity separation of material thrown thereagainst, and against which there is a fan action induced by the ribs and roller-shafts, when the machine is in operation.

6. In a pulverizing-machine, a practicall inclosed pulverizing-chamber formed at t e bottom by a pulverizing-pan, at the sides by a surrounding drum or casin and at the top by a housing open only at t e center; a revolving table sup orted beneath the housing and carrying ro ler-supporting shafts and having strengthening-ribs underneath, said table also being provided with openings at the center, and an outside and an inner screening-surface slantingly disposed about the pulverizing-pan and in close proximity one to the other; said pulverizing-pan being formed with a grinding-surface having a substantially parallel inclination to the slant or incline of the screening-surfaces.

In testimony whereof I aflix my signature in the presence of two subscribing witnesses.

GEO. LEWIS PRATT.

Witnesses:

WILL D. HANCOCK, T. B. FORD

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