US1479242A - Apparatus for grinding materials - Google Patents

Description

Jan. 1, 1924 l N. c. JOHNSON APPARATUS FOR GRINDING MATERIALS Filed sept. lo 1921 2 sheets-sheet 1 y l l w16/ y v mmamtoz ../za/a 6705125012 @51j @Hom/w1# t Jan. 1, 1924 N. C. JOHNSO N APPARATUS FOR GRINDING MATERIALS 2 Sheets-Sheet 2 Filed Sept. l0 1921 patented dan. ll, i924'.

intacta PATENT FFHCE.

NATHAN C. JOHNSON, OF ENGLEWOOD, NEW JERSEY.

APPARATUS FOR GRINDING MATERIALS.

Application led September 10, 1921. Serial No. 499,766.

concern:

I, NATHAN C. JoHNsoN, a citizen of the United States, and a resident of Englewood, county of Bergen, and State of New Jersey, have invented certain new and useful Improvements in Apparatus for Grinding Materials, of which the following is a specification. f

The invention relates to apparatus for grinding various substances.

Heretofore, grinding in ball mills has frequently been accomplished by means of large quantities of pebbles or balls of relatively large diameter andv mass, falling under the acceleration of gravity from a position adjacent a high point of a revolvcontainer down upon other pebbles o r To all whom t may Be it known that in bals and upon the materials to be comminuted. Such mills are bulky in size, require much power and are slow in action, for several reasons; large masses of large pebbles are necessary to secure adequate grinding, entailing large units, a large part of the charge must be lifted idly in the container before falling in useful work, and, since the pebbles are large, the useful points of contact are relatively few in number, with consequent slow action on ground. rl`he present invention overcomes these and other disadvantages, and effects grinding of desired substances in an effective and improved manner, by the apparatus hereinafter described.

ln the invention, in its preferred aspect, use is made of a relatively great number of permanent grinding bodies, each of small mass but with a. correspondingly large number of points of contact, and having a kinetic energy, by reason of high-velocity mass flow, comparable to that of fewer balls of larger mass falling by gravity. The material to be ground is min led with these small grinding bodies or bal s, and the combined mass caused to move rapidly, with rapidly changing velocity, along one or more paths rapidly wherechanging in direction, by compacting of the mass. violent-interparticle attrition, and a rapid and thorough comminuting of the material to be ground are effected. These results are produced by subjecting the mass to, such centrifugal force as to give it compact high-velocity mass flow, and diverting the flow inwardly atinthe materials to be with changing velocities of all portervals these effects taking place tions 0f the mass, in continuous cycles, actions arev produced and brought about.

Various useful and improved e'ects and features of the invention will be more jfully described hereinafter.

The principal object of the invention is the production of novel and eiiicient appa'- ratus for grinding various materials.

The invention consists yin the novel features and combinations of parts hereinafter shown and described in their preferred forms; and the invention is more particularly set forth in the appended claims.

Further objects and advantages of the invention will more fully appear from the following description and the accompanying drawings illustrating the preferred form of apparatus comprised within the invention.

In order that the invention may be more clearly understood attention is hereby directed to the accompanying drawings illustrating the preferred form of apparatus.

Referring to the drawings:

Fig. l is a vertical sectional view of grinding apparatus embodying the referred form of apparatus comprised within my in-l vention, this section being taken on line 1-1 of Fig. 2; y

Fig. 2 is a horizontal section taken on line 2-2 of Fig. l;

Fig. 3 is an enlarged view of a mass defleeting' blade used inthe apparatus together with supporting means therefor; and

Fig. 4 is a section taken on line 4-4 of Fig. illustrating additionally a portion of the revolving bowl or container.

Fig. 5 is an enlarged detail of construction showing in vertical section the edge portion of the rim of the bowl and the stationary cover with the inclined fan blades secured to the outer surface of the bowl,

and

Fig. 6 is a vertical section taken on line whereby the desired of its diameter being effective. The bowl is preferably made up in sections, and it may, as shown, consist of a bottom lsection 2 and an upper section 3, preferably formed of hard metal such as manganese steel. The lower section 2 may be provided with an olf-set iange 4 so as to provide a shoulder 4l for receiving the upper section 3. The sections may be secured together in any suitable manner as by bolts 5 extending through the flange 4 of the lower section and an outwardly formed flange 6 on the upper section.

The bowl may berotated in'any suitable manner as by means of a beveled gear 7 on shaft 8, gear 7 engaging with a beveled gear 9 formed on a member 10 which is centrally secured to the under side of the bowl by suitable means such as bolts 11. Shaft 8 is suitably supported by bearings 12, 12, shaft 8 being rotated in any suitable manner from an electric motor or other source of y power. As shown in the drawings shaft 8 may be provided with a gear 13 which meshes with a pinion 14 which carries a sheave 15 over which runs a driving belt 16.

Member 10 carryin beveled gear 9 is mounted for rotation 1n any suitable manner. As is indicated in the drawings, member 10 may rest upon a bearing within a boss 17 formed on the fixed frame member 18 of the machine. The bowl is provided. with an upwardly extending central cap piece or projection 19. A vertical shaft 2) extends downwardly through yprojection 19 and through members 10 and 17. This shaft 20 may be provided with a suitable head at, its upper end and with a washer or late 21 adjacent its lower end, anti-friction earings 21,1 being provided between washer 21 and a lixed member 22 secured within boss 17. f Shaft 20 may be screw-threaded at its lower end and provided with a nut 23 for holding washer 21 in engagement with its bearing. Member 10 is provided with a downwardly extending central portion 10't 'within boss 17 which is rotatably mounted on a .ball bearing or other suitable anti-friction bearing 24 above the fixed member 22.

As shown in the drawings the bowl is cov'- ered by a cover plate 25 which is supported by brackets 26 extending from upri ht frame members 271. of'which any suita le number such as four may be provided mounted at intervals around the bowl.l The cover plate is provided with openings therethrough through which the dedecting vanes indicated at 27 may extend, these vanes preferably being pivotally secured each to one of the uprights 271, asy by means of the hinged connection indicated at 28.

Means for causing air to sweep into the bowl and to then rise therefrom carrying with it material which has been sucientlv iinely ground, is also provided in a form Laramie well known to the art of air separation. This may take the'form of a downwardly extending air conduit 29 and an uptake member 30 both mounted in position above the cover plate 25 which is provided with a suitable opening, the uptake member being centrally arranged with respect to the bowl and the air intake conduit 29 being arranged around the same center. Air may be forced downwardly through conduit 29 by any suitable blower, such as is indicated diagrammatically at 31. The belt connection 32 shown in iFig. 1 as extending upwardly from shaft 8 to a shaft 321, is used for operating a mechanism for continuously feeding the material to be ground into an opening in the side of the uptake member 30, this not being included in my invention. The feed mechanisln is adjusted to'keep up with the grind' 111g capacity of the mill and the; removal of fine material by the air sweep. v-

The deflecting members indicated generally by reference character 27Vv are preferably hlngedly connected, as stated, to standards 271, so that they may be swung upwardly out of the bowl when this is desired for any purpose such as the renewal of the blades. In the preferred form of these deiiecting members each one is provided with a top plate 33 to which the hinge connection is secured. Each deflecting member is provided with a downwardly extending deiiecting member 34, which is preferably cast integral with the top plate 33, this member preferably being made fairlv heav and Isubstantial. Member 34 preferab y has a separate and renewable blade member 35 pivotally secured thereto, blade mmeber 35 being preferably formed of steel, or i other suitable material, and being adapted to engage against the surface of bowl 1. This renewable blade 35 is pivotally connected to the edge portlon of blade member 34 by Asuitable means, as by securing member 35, by means of screws 36, or the llke, to a sleeve member 37 through which extends a,hinge lpintle, 38, the lower end of which/extends t rough a lug 39 adjacent the ybottom of the blade member 34. The top .-,fplate 33 of the casting is provided with ahollow boss 40 extending upwardly therefromat a suitable angle to receive the upper end of pintle 38, plate 33 being provided With a Suitableopeningthrough which intleI 38 extends. 'Q'lhe upper end of the inge pintle inabe ,received in -a screw plug 41 mounted in t e upper end of the boss 40, j

' container,

acreage service. Blade`35 may be removed by re- -moval of screws 36.

throughout its length. rlhe inner or mass v engaging face 44 of the substantial portion 34 of the blade construction is preferably concave `along its length as well as across its width. The renewable blade 35 is so locate and positioned against the side of the bowl as to form an acute angle with the side of the bowl to the rear of the entering edge of blade 35, the inner face of blade 35 being inclined against the direction of flow of the mass in the bowl when the latter is rapidly rotated, as stated. The concave face 44 of blade member 34 serves as a continuation of the surface of blade 35 to divert the flow of material from the inner surface of the side wall of the bowl toward the center of the bowl. The blade member 34 is provided with a short approximately horizontal flange 45 over which a portion of the mass of material will flow as it is diverted inwardly by the curved surface 44 of the blade structure. rlhe operation of these parts will be more fully described hereafter. The bot-tom of the bowl is preferably provided with heat absorbing vanes 46 eX- tending downwardly therethrough, and a stationary jacket 47 may be provided about the bowl or a portion thereof. With this construction, an external. source of heat (not shown) being any desired temperature may be eected, varies 46 serving to absorb the heat and the jacket to conserve the same. Heat may be drected into the jacket through opening 4 1.

ln the operation of the apparatus, a charge of materials to be ground may be fed continuouously by appropriate means known to the art into the 'revolving container, the material being passed into the for example, through an opening, not shown, in the side of the air uptake 30. The materials to be ground and the small steel shot, or other permanent grinding bodies, will circulate about the container under the influence of centrifugal force, and will at intervals be diverted or deflected towards the center of the container by the deflect- ing blades 35, 34. The mass ,is compacted by the centrifugal force aga-inst the side wally ofthe container until it is `defiected, in continuous cycles, towards the center of lthe container, when the material and the grinding bodies will be dispersed and separated from each other, the form of the mass suc-h as to turn the material'over and spread it out more or less in fan shape as it is diverted away from the sides of the bowl.

provided grinding at deflecting members being' The air which enters the bowl through the conduit 29 willbe given a swirling motion within the bowl partl because of its passage through the spira ly form-ed portion 48 of the intake, and partly because ofy the rotation of the bowl. During the dispersion of the steel shot or grinding bodies they will be thoroughly cleansed by this air and the latter leaving the bowl by the uptake passage 30 will carry with it d all of the material which has been ground to suflicient fineness, this finely ground material being deposited in a suitable vessel, such as the dust collecting chamber indicated at 49, in well-known manner. After passing into chamber 49 and being relieved of its charge of ground material the air is returned through conduit 29 to the bowl, to again take up a charge of ground material, in repeated cycles.

llt will be noted that the small grinding balls, or bodies, together with the material to be ground, travel in a multiplicityI of.

continuous streams traversing defined paths in which breaking, crushing and comminuting of the charge of material is effected by the interparticle attrition of the material and by the oompacting of the mass under the induence of centrifugal force against the walls of the container and against the defiecting blades as the mass passes over the same. When the mass is deflected by the deflecting vanes its velocity is momentarily altered, and siderable extent turned over, streams of material adjacent the upper edge of the bowl being directed downwardly by each vane encountered and material rising on an inclination, to a considerable extent, =being directed upwardly, or permitted to continue its upwardly inclined course, by the vanes, so that upper elements of the stream will become lower ones, and lower elements will become upper ones. Upper elements move at a higher velocity than lower ones, under centrifugal force, because of the greater radius of the upper part of the bowl. Each portion of the mass, which is at any moment deflected inwardly will shortly again come under the influence of the centrifugal force and be accelerated up to a velocity in accordance with its position on the side ofthe bowl. Accordingly, if the mass is assumed for convenience as tilarnented, diering velocities will be imparted to the various filaments of the mass, incident to which there will be a violent rubbing of the particles of the mass one against the other and of the permanent grinding bodies against the material to be ground.

The result of the interparticle attrition described and of the compacting of the mass, by centrifugal force and diversion, as the mass continuously circulates, serves to break down and to comminute all particles of the at the same time it is to a con-v Ulu charge in an extremely rapid and thorough manner so that the charge is reduced to requisite fineness in a very short time. It is obvious that any materials either hard or soft may be ground or comminuted by the invention.

According to the preferred manner of practicing the invention, as for example in the pulverizing of anthracite coal or of Portland cement clinker, the requisite charge of materials to be ground and the requisite number and amount of grinding bodies, preferably small hard steel shot, are placed in the bowl.` The quantity of the small balls or grinding bodies will vary from several pounds to several tons according to the size of the machine and the nature of the material to be ground. The charge or rate of introduction of material to be ground will vary according to its nature, the size of the unit and the degree of comminution desired, but usually the mass of grinding bodies will be relatively great in proportion to the charge being ground.

When the container is in rotation these grinding bodies, or shot, will move outwardly across the bottom of the container and, under the action of centrifugal force, upwardly along the outwardly flaring sides of the container until a zone of greatest diameter is reached. At this point the greatest velocity is attained, and the speed and centrifugal force incident to the speed are sufficiently great to produce compacting of the mass and high velocity mass flow; ll have found that a peripheral velocity at the rim of the container of approximately 1500- feet per minute is sufficient to give the'desired flow to the mass when apparatus of the char# acter shown .herein is utilized. Under the momentum of the mass 1t 1s caused to circulate at high 'velocity in a steady stream or streams along one or more predetermined paths (determined by the shape of the container and the location, number and shape of the stationary blades or mass deflecting devices) these paths rapidly changing in direction. During the passage of material over each blade or mass deflecting device an intensified compacting of the mass is caused by the retardation of the high velocity mass flow at such point, and throughout the process`a violent interparticle attrition is caused as the velocities of the various portions of the mass are altered by the enforced circulation along the predetermined paths` whereby extremely rapid violent and thorough grinding of the materialis brought about.

Furthermore, 4as stated above, as the swiftly flowing mass of shot and more -or less finely ground material leaves each deflecting blade, to follow' its predetermined path towards the center of the container, the mass is spread out fan-wise through the air so as to permit a thorough cleansing of the Maaate ground material from the grinding bodies and the removal of the fine material from the bowl with the air, while the grinding bodies which are too heavy to be thus removed by the air will remainvbehind to be used again and again in repeated cycles.

It is further to be understood that any portion of the charge to be ground which is not of sufficient fineness thus to be removed returns, together with the grinding bodies, to a point adjacent the center of the bot-tom of the bowl, from which it again moves outwardly and, as it attains velocity with rotation with the container, upwardly along the sides of the bowl to again be compacted, subjected to high velocity mass flow, interparticle attrition, diversion and intensified compacting by the fixed vanes or blades, spreading and cleansing bypassage through the air after leaving the blades, impingement on the bowl adjacent the center thereof, and so on in rapidly repeated cycles.

It is to be understood also that while grinding may thus be effected on the material continuously fed in and continuously removed, the invention is equally applicable to the grinding of single charges of material. lt will also be noted that either wet or dry material may be operated upon and that grinding at any desired temperature may be effected, as stated above, as for example in the carrying out of solvent or distillation processes.

lft will be noted that the grinding medium preferably used comprises a relatively large number of bodies each of small mass, these bodies having in operation a considerable kinetic energy because of their velocity, the small grinding bodies also, 'because of the considerable number of the same used, presenting a multiplicity of points of contact to the material to be ground. Because of the small size of the grinding bodies also, they, together with the charge, constitute a mass which is readily deflected from its circumferential path around the bowl by means of thefixed deflecting blades. Accordingly the expenditure `of power is not sensibly increased-by such diversion of the grinding bodies and charge, beyond the power reuired to rotate the container and a portion of the charge plus the power required lto accelerate another portion of the charge up to aproper velocity.

l It will be further noted that if we consider the crushing of a lump or particle of material at any point in -the path of the materials in the bowl, it is at once evident, since, the grinding medium is one which is deformable and at the same time is being compacted with pressure due to'the centrifugal force, that the crushing of any lump of material is at once followed up closely by the deformable medium to immediately produce finer crushing, the grinding medium lll() bowl in time to pass over material between the aaaaaaa constituting in edect a Huid solid having a high static pressure and a large number of points of contact, surrounding and pressing upon each portion of the material to be round.

lt will be noted that the constant removal of the finely ground material permits increased output for given application of ower in comparison with apparatus in which the balls or grinding bodies are cushioned by a considerable portion of the fine material retained in the mass.

In further reference to the shape of the deflecting vane in the preferred form of the invention, it should be said that the lower flange or shelf 45 serves several purposes. It serves to protect the lower edge of deflector 34 from wearing away, since an upwardly inclined filament or portion of the stream of material which would otherwise strike the bottom-edge of -member 34 is deflected from the lower surface of shelf 45 without damage, this portion of the stream again rising along the wall of the the shelf 45 of a subsequent blade 34. The portion of the stream which passes above shelf 45 will, in part, be deflected downwardly by surface 44 of member 34 against the upper surface of shelf 45, fromwhich it must glance, so that the lower edge of the curved surface 44 will not be worn by the passage of the material over the same. At the same time there is an intensified compactin of the material and attrition of the partie es above each shelf 45, `because of the action described.

llt should likewise preferred form of construction, esca o rim of the bow and the stationary cover 25 is largely prevented by the provision of inclined fan blades, indicated at 50, secured to the outer surface of the bowl immediately below the upper edge thereof and below the dange 51 at the outer edge of the cover (Figs. 1, 5 and 6), these fan blades being arranged as they rotate with the bowl to blow air towards the joint between the bowl and the cover, and thereby eect an air seal of this joint.

While l have described my invention according to the preferred forms of machines embodying the same, it will be obvious to those skilled in the art, after understanding my invention, that various alterations, modifications and substitutions may be made without departing from the spirit and scope of the invention, and l aim in the appended claims to cover all such modifications.

1. lln a grinding machine, the combinabe noted that, in the tion of an upright rotatable bowl rotatable l at such speed as to subject the contents thereof to the action of centrifugal force, and one or more stationary mass deflecting devices positioned adjacent the sides of the bowl each having a mass entering edge extending upwardly towards the upper edge of the bowl, a concave mass deflecting face to the rear of said edge in the direction of movement of the material in the bowl, so as to engage the material adjacent the side of the bowl and deflect it inwardly and a bottom horizontal forwardly extending flange over which will flow material directed inwardly by said face. j

2. ln a grinding machine, the combination of an upright rotatable bowl rotatable at such speed as to subject the contents thereof to the action of centrifugal force, a fixed member adjacent the bowl, and a mass deecting device comprising a plate hinged to said fixed member and extending inwardly over member extending downwardly therefrom within the bowl and a blade having a mass entering edge, pivoted to said curved member and spring-pressed into position to cause said edge to extend closely adjacent to the side of said bowl, said curved member having a concaved face whereby material within thebowl passing over said bladewill be deflected away from the side of the bowl.

3. In a grinding machine, the combination of an upright rotatable bowl rotatable at such speed as to subject the contents thereof to the action of centrifugal force, a fixed member adjacent the bowl, and a mass deflecting device carried by said fixed member, comprising a curved member extending downwardly within the bowl and a blade having a mass entering edge extending forwardly from said curved member into a pof sition inv which said edge lies closely adjacent tb Allthe side of said bowl, said blade being removably hinged to said curved member and said curved linfiinber having a concaved face whereby material within the bowl passing over said blade will be defiected away from the side of' the bowl.

4. ln a grinding machine, the combination of an upright rotatable bowl rotatable at such speed as to subject the contents thereof to the action of centrifugal force, a fixed member adjacent the bowl, and a mass deflecting device carried by said fixed member, comprising a curved member extending downwardly within the bowl and .a blade having a mass entering edge extending forwardly from said curved member into a osition in which said edge lies closely adlacent to the side of said bowl, said blade in removably hinged to said curved mem er and said curved member having a mass engaging'face, concaved and inclined inwardly towards the center of the bowl, and a bottom horizontal forwardly extending flange, over which will ow material directed inwardly by said face.

5. In a grinding machine, the combinathe rim of the bowl, a curved tion of an upright rotatable bowl rotatable at such speed as to subject the contents thereof to the action of centrifugal force, a stationary cover member above said bowl, D having an outwardly and downwardly extending flange, and fan blades secured on the exterior surface of said bowl adjacent aimee/ie the upper edge thereof, arranged to force airv against the outer edge of the joint between said bowl and cover member. 10

ln testimony whereof, ll have signed my name to this specification.

NATHAN o. JoHNsoN.

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