US3326476A - Rotatory mills - Google Patents

Description

June 20, 1967 F. DE LOS SANTOS IZQUIERDO 3,3 7

ROTATORY MILLS 2 Sheets-Sheet 1 Filed March 1, 1965 INVENTOR FEoERico DE LOS :sxxwros Iz uiE/ana J n 1967 F. DE 1.05 SANTOS IZQUIERDO 3,326,476

ROTATO RY MILLS Filed March 1, 1965 2 Sheets-Sheet 2;

INVENTOR FEoERico DE L05 SANTOS IzquiERno United States Patent 3,326,476 ROTATORY MILLS Federico de los Santos Izquierdo, Av. Insurgentes Sur 1510-405, Mexico City, Mexico Filed Mar. 1, 1965, Ser. No. 436,222 Claims priority, application Mexico, Mar. 3, 1964,

76,061 7 Claims. (Cl. 241-55) The present invention is related to the crushing or grinding of materials and more particularly, refers to a rotatory mill wherein the grinding is effected by driving the materials upwardly to be striken by a plurality of impellers or ridges which in turn throw down the materials to strike against the rising materials, all of this being achieved by rotating the mill at high speed.

Hereinbefore, many types of mills have been known in the art which operate under the principle of hammering the material by means of hard members or hammers, or by attrition, or by ball milling; and fluid driven milling, but all these techniques have been highly inefiicient because of the fact that the materials to be ground seriously abrade the metallic portions of the equipment thereby producing a heavy Wear which results in a decrease of efiiciency of performance of the above mentioned mills.

It is therefore an object of the present invention to provide a mill wherein a paraboloid rotatory drum is arranged to accommodate the material to be ground, rotating at high speed to upwardly throw portions of said material against a plurality of stationary impellers or ridges which are arranged on the upper wall of the mill.

Another object of the present invention is to provide a mill of the above mentioned character wherein the material which is being ground creates a protective coating on the inner surface of the drum, thus avoiding excessive wear.

A more particular object of the invention is to provide a mill of the above character which has a very low power consumption and is provided with simple and easy regulatable means for grinding control, and resulting in a very low maintenance cost by reason of being a very compact machine.

Other objects and advantages of the invention will become apparent to those skilled in the art while still others will appear as the following specification of a preferred embodiment thereof proceeds, taken in connection with the accompanying drawings, wherein:

FIG. 1 is a front elevational view, with sections partially removed, of the mill built in accordance with the present invention, showing the inner details thereof;

FIG. 2 is a plan View with sections partially removed, through lines 22 and looking in the direction of the arrows.

According to the present invention, a grinding mill is provided which comprises a rotatory drum, located beneath a stationary horizontal plate or cover provided with suitable ridges or paddles so that when said drum rotates, the material thrown in an upward direction will strike on the said paddles, an external housing provided with means to collect the ground portion of the material, return means to recycle the material which has not been ground to the proper particle sizes, and driving means to provide the rotatory motion of the above mentioned member. The mill of the present invention is also provided with means to control the particle size of the discharged material, means for introducing entraining air into the milling section, means for regulating the flow of air thereinto, and means to dynamically balance the rotatory portions of the mill.

Having now more particular reference to the drawings, a rotatory mill is provided comprising a main housing 1 supported by bases 2 suitable to be anchored to the 3,326,476 Patented June 20, 1967 floor. The housing 1 is provided interiorly thereof with a pair of round plain covers 3 and 4 between which a sleeve 5 is fastened by suitable securing means for the purpose of supporting a plurality of bearings which are particularly illustrated as ball bearings 6, 7 and 8 to journal the vertical axle 9 for a purpose which will become clearly apparent hereinbelow.

The housing 1 is provided at the lower portion thereof, on the section between covers 3 and 4, with a plurality of openings 10 horizontally arranged throughout the circumference thereof in order to provide ports for the entrance of air into the mill.

Cover 3 comprises a plurality of openings circumferentially distributed thereon and a plate member 12 is arranged under cover 3 also comprising a plurality of openings which in certain positions of member 12 will match with the openings 11 of cover 3.

Plate member 12 is loosely supported over a flange or shoulder formed at the upper portion of sleeve 5 and is provided with a rack at least on one portion of the periphery thereof, having a suitable number of teeth to mesh with the teeth of a cylindrical gear 13 journalled on the side Wall of housing 1 and provided with a handle or crank 14 to thereby rotate it at the will of the operator. With the above arrangement, and supposing that the openings 11 of cover 3 and the openings of member 12 are in registry, when the operator rotates handle 14 these two series of openings will be moved out of the registering position thereby restricting the free flow of air into the device and consequently controlling the admission of air into the inner parts of the mill. This handle 14 can obviously be replaced by a suitable wheel or pulley which can be acted upon by means of a motor drive or the like in order to make this operation fully mechanical or automatic.

The axle 9 supported on the ball bearings 6, 7 and 8 is fixed by suitable means to a cylindrical double walled drum 15 which is the main operating member of the mill.

Cylinder 15 is provided on the outer wall thereof with a plurality of inclined paddles 16 arranged to suck in the air admitted through the openings 10 and through the valve openings 11 and 12 and throw it through the annular space between the cylindrical wall 17 of the cylinder 15 and the cylindrical wall of housing 1 in order to introduce it under certain pressure into the mill.

The inner wall of the cylindrical drum 15 has a semispherical shape and provides a paraboloid receptacle 18 for a purpose which will be fully described hereinbelow.

Chamber 19, formed between the cylindrical drum 15 and the paraboloid receptacle 18 which upper ends are joined together as clearly shown in FIG. 1 of the drawings, is partially filled with a liquid heavy material such as mercury or the like which dynamically balances the rotatory motion of this device regardless of the relative positions and weights of the solid materials contained within the receptacle 18, inasmuch as it has been found that this heavy liquid material tends to distribute itself in such a way that the weight around the periphery of the rotatory member will remain constant and duly balanced regardless of the partial accumulations of solid materials in a predetermined portion of this rotatory member, thereby constituting an automatic dynamic balancing device which prevents undue vibration of the mill when the latter is rotated at high speeds.

At the mouth of the paraboloid receptacle 18 a funnel member 20 is arranged, fixed to the upper portion of housing 1 and with its frusto conical mouth registering with that of receptacle 18, to guide the materials into the receptacle 18 as will be described below. The cross section of this funnel member can be seen in A in FIGS. 1 and 2 of the drawings.

ference thereof as shown in FIG. 1 of the drawings. These ridges 23 can have a plurality of forms and sizes according to the material to be ground.

Cover member 22 can be vertically adjusted in respect to funnel member 29 by means of threaded bolts 21 in order to control the gap therebetween, through which the ground material can leave the mill when ground to a desired particle size. The particle size of the material leaving the mill will obviously depend on the gap provided between members 20 and 22.

Cover member 22 is provided with a hopper 24- which surrounds the housing 1 as shown in FIG. 1 of the drawings and is formed so as to have an inclined or sloping bottom to provide for the sliding of the materials to the lower portion thereof. A discharge 25 is arranged at the lowermost portion of the hopper 24 for the product of the mill.

At the upper portion of cover member 22, centrally arranged thereto, a vertical pipe or duct 26 is provided, having a horizontally directed branch 27 for charging the materials to be ground into the mill, and an upper vertical pipe section 28, to discharge the finely divided materials ground in the mill.

The axle member 9 is provided with a pulley 29, which serves as a drive to rotatively move the mill, fastened to the axle 9 by means of nut 30 or other suitable means. This pulley 29 receives its motion from a motor (not shown) such as is conventional in the art.

The performance of the mill of the present invention can be described as follows:

Drum 15 is rotated at a very high speed by means of the motor (not shown) and the material to be ground is fed through the duct or branch 27, falling down by gravity into the rotatory drum. This material builds up a protective cover on the inner walls of the mill, by following the paraboloid profile of the drum or receptacle, until this receptacle is covered by a predetermined thickness of material. After having achieved this thickness of material, the material which furtherly falls into the receptacle, is upwardly thrown following a predetermined path against the stationary ridges of paddles 23 of cover 22. When the material strikes the ridges 23, the material rebounds and is thrown in descendant paths changing its momentum a number of times, and is again thrown upwardly by the rotatory drum 18, thereby each time striking against some particles of material which are travelling in the opposite direction, effecting the grinding operation by the striking action of the ridges 23, but mainly by the action of the upper surface of the layer of materials provided in the inner wall or drum 18, and because of the striking of the rising portion of the material with the descending ones thereby avoids unduly rapid wear of the inner portions of the mill.

At the same time, the paddles 15 provided at theouter walls of cylinder 15, acting as a fan, drive air suctioned through openings and through the regulatable openings 11 and 12, to be injected into the mill proper, through the gap provided between the drum 15, 18, and member 20, this high speed air stream having as its function the provision of a forced draft to entrain finely divided materials in order to drive them out of the drum through duct 26 when the material is to be very finely ground and the members 20 and 22 are joined together leaving no gap therebetween.

In view of the above, it can be seen that the present mill can grind the material to the desired particle size, the latter depending on the separation or set of the members 20 and 22, which adjustment is made by means of the threaded bolts 21.

When a very fine dust is desired, then the gap between members 20 and 22 is completely closed by a proper 4- adjustment of bolts 21, and the air drives the dust through the vertical duct 26 whence it is passed, if desired, to a cyclon or any other type of device for separating gases and solids.

When coarser particles are desired, then members *20 and 22 are separated in order to provide a suitable gap, and the material leaves the mill thrown by the centrifugal force, through the gap between'these two members, falling into the hopper 24 and sloping down the slope thereof in order to be discharged through duct 25.

From the above it can be seen that a very simple mill is provided wherein the material which is to be ground suitably protects the inner walls of the rotatory receptacle, thereby avoiding any type of heavy wear. Also, all material entering after the protecting wall has been formed is violently thrown upwardly, in order to strike against the ridges and rebound to then strike against the free surface of the protecting wall of material, which is rotating at a very high speed and also striking against other material which it encounters in its way therefore achieving the grinding operation by means of the striking of metal lic parts against the material, but mainly by the striking of some particles of material against others, thus avoiding any rapid wear of the device.

The present mill provides very important advantages with respect to all the mills of the prior art, inasmuch as all the material introduced therein is treated exactly in the same way without any discrimination, and also said mill provides for a very low power consumption due to the very simple mechanism thereof, and due to the fact that the only movable portion is the drum 15 together with its receptacle 18, which rotation is not precluded by any type of braking action from the part of the material or otherwise. The degree of grinding of the material can be very easily controlled by the adjustment of a few bolts 21. The maintenance cost is very low because the present device is a very compact and simple one, having very little wear.

While in the above a preferred embodiment of the present invention has been described and illustrated in detail, it must be understood that said embodiment is not to be construed as limitative of the invention but rather as illustrative thereof, and that many variations and modifications can be effected in practice, within the same principle, without departing from the true spirit and scope of the invention, as stated in the appended claims.

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

1. An improved mill having means suitable to regulate the degree of thickness of the ground material, which comprises, in combination, an outer cylindrical housing, openings in said housing for the admission of air into the mill means for altering and regulating air entrance into said mill, a rotatory drum having an open mouth and arranged within an upper chamber formed in said housing beyond the regulating means for the admission of air, a plurality of inclined impeller paddles on the external peripherical cylindrical surface of said drum, for driving air through said openings and through said air flow regulating means, a second drum within said first drum, said second drum having a dished shape and being firmly fastened to said first drum for rotation therewith, a ring member directly over the open mouth of said drums, a cover on said housing, a hopper surrounding said housing and communicated with the mouth of said rotatory drum to receive ground material, means for regulating the gap between said ring member and said cover to provide a grading control for the admission of material into said hopper, a plurality of stationary ridges located at the undersurface of said cover, means for extracting finely divided material through said cover, and means to dynamically balance the rotatory drum regardless of the random distribution of weight therein.

2. A mill according to claim 1, wherein said means to dynamically balance the rotatory drum comprises a chamber formed between said first rotatory drum and said second rotatory drum, filled with a heavy liquid material such as mercury, in order to compensate for and dynamically balance said rotatory drum when the weight of the material is not uniformly distributed Within said second drum.

3. An improved mill having means suitable to regulate the degree of thickness of the ground material, which comprises, in combination, an outer cylindrical housing, openings in said housing for the admission of air into the mill, an intermediate horizontal stationary partition within said housing forming an upper chamber and a lower chamber, said intermediate stationary partition being provided with a plurality of openings circumferentially distributed therethrough, a plate member parallel to said intermediate partition, centrally journalled within said housing, and provided with a rack at the outermost portion thereof, a gear meshed with said rack and journalled through the side Wall of said housing, a crank to rotate said gear and to consequently rotate said plate member through a certain angle of rotation, a plurality of openings in said plate member, in positions such that they will be able to register with the openings of said intermediate partition, thus providing a means for regulating the entrance of air into said mill by rotating said gear and rack mechanism, a rotatory drum within the upper chamber of said housing, driven by a vertical axle passing through said housing, a plurality of inclined impeller paddles on the external peripherical cylindrical surface of said drum for driving air through said openings and through said air flow regulating means a second drum within said first drum, said second drum having a dished shape, and being firmly fastened to saidfirst drum for rotation therewith, a ring member having an inner tapered funnel-like surface directly over the open mouth of said rotatory drums, a cover on said housing, a hopper surrounding said housing and communicated with the mouth of said rotatory drum to receive ground material, means for regulating the gap between said funnel-like ring member and said cover to provide a grading control for the admission of material into said hopper, a plurality of stationary ridges located at the undersurface of said cover, means for extracting finely divided material through an upper duct provided on said cover, and means to dynamically balance the rotatory drum regardless of the random distribution of weight therein.

4. An improved mill according to claim 3, wherein said means to dynamically balance the rotatory drum comprises a chamber formed between said first rotatory drum and said second rotatory drum, filled with a heavy liquid material such as mercury, in order to compensate for and dynamically balance said rotatory drum when the Weight of the material is not uniformly distributed within said second drum.

5. An improved mill according to claim 3, wherein said means for regulating the gap between said funnel-like ring member and said cover comprises a plurality of set screws or bolts threadedly engaged through bores in said cover member and bearing against seats provided on the top of said ring member.

6. An improved mill according to claim 5, wherein said set screws can regulate the gap between said cover and said ring member from a fully closed position to avoid passage of material therethrough and to force the material which is finely divided by air entrainment through said cover member, said cover member being provided with a centrally arranged vertical pipe to provide for the passage of said finely divided material.

7. An improved mill according to claim 6, wherein there is provided in said vertical pipe a sidewardly extending branch to serve as a loading chute for charging coarse and unground material.

References Cited UNITED STATES PATENTS 229,787 7/ 1880 Withec 241-292 1,605,025 11/1926 Hildebrandt 24l47 1,697,704 1/1929 Wood 24l55 X 2,031,289 2/1936 Van Law 24l284 X 2,562,560 7/1951 MacArtney 24l275 X ANDREW R. JUHASZ, Primary Examiner.

Claims (1)

1. AN IMPROVED MILL HAVING MEANS SUITABLE TO REGULATE THE DEGREE OF THICKNESS OF THE GROUND MATERIAL, WHICH COMPRISES, IN COMBINATION, AN OUTER CYLINDRICAL HOUSING, OPENINGS IN SAID HOUSING FOR THE ADMISSION OF AIR INTO THE MILL MEANS FOR ALTERING AND REGULATING AIR ENTRANCE INTO SAID MILL, A ROTATORY DRUM HAVING AN OPEN MOUTH AND ARRANGED WITHIN AN UPPER CHAMBER FORMED IN SAID HOUSING BEYOND THE REGULATING MEANS FOR THE ADMISSION OF AIR, A PLURALITY OF INCLINED IMPELLER PADDLES ON THE EXTERNAL PERIPHERICAL CYLINDRICAL SURFACE OF SAID DRUM, FOR DRIVING AIR THROUGH SAID OPENINGS AND THROUGH SAID AIR FLOW REGULATING MEANS, A SECOND DRUM WITHIN SAID FIRST DRUM, SAID SECOND DRUM HAVING A DISHED SHAPE AND BEING FIRMLY FASTENED TO SAID FIRST DRUM FOR ROTATION THEREWITH, A RING MEMBER DIRECTLY OVER THE OPEN MOUTH OF SAID DRUMS, A COVER ON SAID HOUSING, A HOPPER SURROUNDING SAID HOUSING AND COMMUNICATED WITH THE MOUTH OF SAID ROTATORY DRUM TO RECEIVE GROUND MATERIAL, MEANS FOR REGULATING THE GAP BETWEEN SAID RING MEMBER AND SAID

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