US2575380A - Crusher mill - Google Patents

Description

G. W. BORTON- CRUSHER MILL 2 SHEETS-SHEET l Filed Dec. 8, 1949 ,.f. L.: I l, ,www um OOOOmuN hh Q I, M m m en? N. `v O ILH w@ M-||.|M I iWnw; v .N ON U Im N- O m IH m fl, N mm m N w INVENTOR.

GEORGE W BORTON Nov. 20, 1951 G, w. BoRToN 2,575,380

A CRUSH'ER MILL v Filed Dec. e, 1949 2 SHEETS-SHEET 2 INVENTOR. GEORGE VV. BORTGN ATTORNEY Patented Nov. 20, 1951 UNITED STATES PATENTl OFFICE CRUSHER MILL George W. Burton, Philadelphia, Pa., assignor to Pennsylvania Crusher Company, Philadelphia, Pa., a corporation of New York Application December 8, 1949, Serial No. 131,747

3 Claims.

This invention relates to breakers and more particularly to an improvement in the Bradford type of breaker.

It is an object of this invention to provide a Bradford type breaker which crushes by hammer impact and shearing.

It is a further object of this invention to provide a mechanism in which the material is subjected to a hammer fracture and shearing action under conditions limiting the forces applied and predetermining the strength of the impact and shearing action.

Other objects and advantages of this invention will become clear upon reading the following description taken with the accompanying drawings in which:

Fig. 1 is a vertical section of a Bradford type breaker taken on the axis of the driving means; and

Fig. 2 is a vertical section of the breaker taken radially of the rotary hammers on the line 2-2 of Fig. 1.`

Fig. 1 shows a crusher composed of a rotatable drum I within which is a rotor 2 carrying pivoted hammers 3. section (Fig. 2), the drum I containing lifting shelves 4 is shown rotating clockwise as viewed from the entrance end for carrying up coal to be broken by dropping. A hammer carrying rotor 2 rotates counterclockwise with its hammers 3 for breaking by impact and shearing the coal in the drum I. The drum I is contained in a. casing 5 which as shown in Fig. 1 is provided with an `opening' in one of its side walls 23 through which the drum I and rotor 2 are driven. The cylindrical outer wall of the drum I is made up of perforated plates 6 through which particles of coal broken up inside the drum I fall out into the casing 5. The casing 5 is provided with a discharge opening 'I at the bottom through which the screened particles are discharged into a suitable receptacle.

A conical feed end 8 is formed on thefopposite side of the drum I from the driving means and a feed chute 9 extending into the drum I projects over the lip of the conical end 8. The lifting shelves 4 are provided with slots IU for the .passage of projections 2| extending from the hammers 3 with predetermined axial clearances 24 and radial clearances 25 as shown in Fig. 1. At the feed side of drum I the shelves 4 have unslotted sections II which pick up the intro- Referring to the transverse which is cast integral with a tubular quill I3 and is mounted at one end in an opening in casing 5. The quill I3 is rotatably mounted in pillow boxes I4 and is chain driven through a sprocket I5 mounted on a second spider I6. Through the spider I 6 the rotation of quill I3 turns the drum I. The hammer-carrying rotor 2 is driven by a spindle I1 supported in the quill I3 by bearings I8 and sleeve I9. Rotary motion for turning the spindle I5 is supplied through a pulley 20 mounted on the opposite end from the rotor 2. As viewed in Fig. 2 the drum I is rotated clockwise at a slow rotationa1 speed and the rotor 2 is rotated counterclockwise many times faster than the speed of the drum.

In operation the coal or other material supplied through chute 9 descends into the conical feed end 8 of the drum I and is distributed by the rotation of the drum I. The entrance ends II of the lifting shelves 4 pick up this coal and coal that has not yet passed through the screen plate 6 and carry it up and drop it as they reach the vtop of their path and the dropped coal and other coal from the entrance pass into the hammer area following the entrance space. The hammers 3 moving counter to the lifting shelves 4 strike the coal and reduce it by impact, and projections 2| passing through slots ID also fracture the lumps of coal between the moving parts with a shearing action. Coal on the shelves 4 is constantly carried to the top of the drum I where it falls to the bottom for a repetition of the cycle. Reduction of the particles of the material continues until they reach a iineness suiicientV to pass through the holes 22 of the perforated plate 6 and fall out through the outlet 'I. As the reduced particles pass through the plate 6 and are removed from the bradmill fresh feed enters the mill through the chute 9.-

The size of the largest of the particles discharged is regulated by perforations in the screen plates 6 and the character of the particles is largely determined by the spacings between hammer projections 2I and the shelf slots I0. The distance between the edges of the projections 2I and the slots I0 iniiuences the type of fracture produced by the shearing action between the hammers 3 and shelves 4. The spacing of the hammers 3 from the shelves 4 is adjustable permitting a variation in the shearing action and the size to which particles are reduced by this shearing when caught between the projections 2| and the slots ID.

This invention effects a fracturing of material not only by gravity drop and hammer impact but also by the shearing of the rotating hammers against the material held by the shelves in clearances 24 and 25. The hammers 3 rotating at a speed of the order of 300 to 800 R. P. M. travel much faster than the counter-rotating drum which rotates at a speed of the order of 18 R. P. M.v Consequently the vhigh velocity hammers not. only 'strike the freely falling coal and fracture it by impact but also shear through the masses of coal in front of the shelves. The passage of the hammer projections through the shelf slots exerts a shearing type of .crushing action on the material caught between the hammer and the shelf. This shearing, in contrast l other than by the scope of the appended claims.

with the attrition reduction of the grinding against screen plates, gives a clean sharp fracture.

In reduction of material to a predetermined size by fracturing it is advantageous to avoid the production of fines orfparticles which are smaller than the desired size as these undersize particles "are largely-wasted. In crushing' a material generally more than one fracturing is necessary to reduce the material to the desired size.` Limiting the number 'of nes produced during each fracture ofthe oversize particles increases the enicien'cy of the crushing operation with consequent savings in cost and lmateriali Y v achieves av limitation on the production of fines This 'invention by eliminating attrition.V Attritionis avoided in l this invention by obtaining the iracturingY `of the f material by impact and shearing rather `than grinding the material to be fractured between two surfaces. This elimination of attrition is obtained in part by the radial exibility of the free swinging hammers 3 which may tilt radiallyupon encountering more than a predetermined resistance on the shelves 4 and thus do not produce the Ifra'cturing*which wouldresult vifthehammers -Wererigid Vrinother' advantage of this invention is'pro- `vided in the combination of shearing actions obtained from the clearances 2li parallel to the'axis drum `l the axial edges remain parallel and the j-clearancesmerely enlarge. At the clearances 25 the radial edges of the hammers 3 and shelves 4 approach each other at a sharplyvshearing angle which may be changed by variations in ther tilt of the hammer -3 with relation tothe rradius of the drum I but the amount of the clearances re- `vmains constant. These varieties of shearing angles providedifferent shearing actionsboth of which fracture by a short period of violent contact rather than by slow continuous grinding.

Where there is likelihood of tramp iron or the like 'contaminating the supply, theshearing and lifting'shelves d will preferably be held in radial vlfposition by shear bolts secure'under the ordinary loading of the Worked material but shearing apart under the impact of excessive pressures developed when pieces of iron or other hard tough material are caught between the hammers and shelves which latter then yield to permit the hammers to pass. The machine is then stopped and the tramp iron removed and the shelves restored with replacement of the safety shear bolts.

It will be understood that' the shape of the hammers and the slots may be varied Without departing from the principle of impact and shearing. A wide range of materials may be reduced i 'j `bythe above apparatus and while a specific eX- ample has been illustrated by the use of coal other, substances may be broken up. It is, therefore, intended that the invention not be limited `I claim:

1. A. rotary Crusher mill comprising a drum "rotatable around a horizontal axis and having opposite heads, a rotor having pivoted hammers within the drum, a separate screen forming the periphery of the drum betweensaid heads, shelf means within said drum comprising strips connecting the drum heads and provided witha plurality of longitudinal series of projections directed inward from said screen and separated from each other by intervening spaces, radially extending edges on the hammers of said' rotor passing between and interacting with said projections, meansdriving said drum and rotor inopposite directions at dinerent speeds to'passA said edges through said spaces between said projections so as to fracture material by downward'hammer blows in said spaces during the lifting of said material by said shelf means, and meansdischarging the fragments passing throughlthe peripheral screen.

2. A rotary crusher mill as set forth in claim 1 in which the rotary drum is provided with an enclosing casingY anda feed' chute at theentrance end of the drum and a discharge at the bottom of n said enclosing casing.

' only a single hammer of the rotor is passing gagements for each through the strip projections atl a given time and the crushing effort is correspondingly divided between the multiplicity of hammer and stripenrotation of the rotor.

` GEORGE VV'BORTON.

REFERENCES 'CITED The following referencesare of record in .the

. iile of this patent:

. UNITED STATES-PATENTS

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