US2297391A - Grinding mill - Google Patents

Description

Sept, 29, 1942.

F. CON RAD! GRINDING MILL Filed March 26, 1940 m L A e R N w V. .mH E 0K N TR ND EE W Vmm %A F Patented Sept. 29, 1942 GRINDING MILL Friedrich Conradi, Magdeburg-Hopfgarten, Germany; vested in the Alien Property Custodian Application In lclaim.

My invention relates to grinding mills, wherein the material to be ground is agitated in the presence of grinding elements; and more especially to improvements in gyrating grinding mills f the continuously acting type known for instance from United States Patent 2,117,965 to Kieskalt et al., which are bodily gyrated in small cyles of movement, and through which the material is gravitationally advanced.

The primary object of this invention is toprovide an improved grinding mill of the continuously acting gyrating type set forth and of high efliciency, which is composed of a relatively small number of parts of simple structural design, and wherein various materials of different hardness, including for instance cement clinker, graphite, crushed ore, asbestos, burnt lime, etc. can be rapidly comminuted into powder of great fineness under conditions of economy namely as regards output, power consumption and expenses ,tor repair and maintenance of the grinding mill.

Other objects aimed at by this invention and advantages obtained will become apparent to practitioners in this field as the description proceeds.

The nature and scope of the invention are briefly outlined in the appended claim and will be more fully understood from the following specification taken together with the accompanying drawing, in which Fig. 1 is a section axially taken through a vertically disposed gyrating grinding mill, redesigned according to this invention, and

Figs. 2, 3 and 4 are sections axially taken through vertically disposed gyrating grinding mills of modified design.

March 26. 1940, Serial No. 325,991 Germany March 4, 1939 In its original and simplest form the grinding mill, designed with the objects in view outlined above, and shown in Fig. 1 comprises:

1) A drum shaped, vertically disposed grinding chamber 20 (Fig. 1) having a cylindrical grinding and impulse giving working face 2ihereinafter briefly called impeller face-and a bottom wall 22 formed with discharge holes i,

(2) An apertured lid 32 and a hopper 33 yieldingly connected therewith by a flexible hose 34 for feeding the material to be ground into the mill,

(3) Chains i3, NT or like suspending means for yieldingly supporting the mill and'allowing of the latter being bodily gyrated transversely to its axis. I

(4) A circular grinding element 40 in the form of a disc or ring, having a central intake and a slightly smaller diameter than the cylindrical impeller faced! the grinding chamber 20, and being hereinafter briefly called grinding ring;

said ring'lli gravitationally rests on and receives,

rection of rotation, opposed to that of the gyrating motion of th mill; and

(5) Means are provided for bodily gyrating the mill transversely to its axis in closed cycles of movement, which comprise a rotary shaft 50,

'axially joumalled at the lid and bottom of the mill and being enclosed by a tubular member 5|, unbalance weights i2, 52. attached to said shaft, and an electric motor 59 for rotating it.

In the embodiment of the invention shown by way of an example in Fig. 1 a plurality of spaced partition walls 23 to 3| are charge holes 12 to fill, distributed over their whole area; said partition walls subdivide the mill into a plurality of compartments, in each of which there is a grinding ring of specific design formed at its lower face with a bevelled circumferential edge Al for promoting the passage of the ground material underneath the ring.

According to this invention the spaces between the successive partition walls 22 to 3| are progressively smaller towards the lower end of the mill; likewise the discharge holes 1 to ill! in the successive partition walls are progressively smaller towards the lower end of the mill namely in proportion to the gradually smaller size of the 7 ground product.

The material under treatment gravitationally passes down through the successive compartments, is ground therein between the interengaging surfaces of the grinding rings and the grinding chamber and passes out of the mill through a funnel ,l I.

A great many changes and structural modifications may be conveniently made in the design,

assemblage and cooperation of thevariouscomponent parts of gyrating grinding'mills as shown in Fig. -1 in order to obtain the best results on grinding various raw materials differing in their hardness and other physical properties, without departing from the spirit and the salient ideas of this invention.

In the structurally modified grinding mill shown in Fig. 2 there are means provided capable of adjustment from without the mill for keepprovided having disprise a plurality of spaced double-armed levers l6 circumierentially distributed and engaging the grinding ring by means of a ballshaped pressing element l'l rotatably attachedto lever IS; the said levers, of which one only is shown in Fig. 2, are loaded -by springs l8, thetension of which can be adjusted by means of a screw and nut gear I8 supported by a bracket i9;

Underneath the partition walls p2, p8 which are provided with spaced discharge holes d1, d3 around their periphery, there are iunnel shaped chutes t2, t3 provided for establishing azig-zag course for the material under treatment; the material entering at the center of the grinding ring r3, passes radially underneath the latter towards its periphery, and after having dropped through the discharge holes d! is collected in the chute t1 and gravitationally redirected to the center of the next following grinding compartment.

' with the structurally modified grinding mills shown in Figs. 3 and 4 a plurality of grinding rings are arranged in each grinding compartment:

The grinding rings r5, 11,18, 19 (Fig. 3) are superimposed on each other and formed at their intake holes with bevelled edges g6, g1 adapted to promote the entrance of the material underneath the rings; the rings .16, r1, r8, r9 have alhave difierent diameters.

Heavier grinding rings m, r14, r15 graduated as to theirdiameters and nested within each other, as seen in Fig. 3, may be used to advanthe impeller face of chamber M respectively,

. revolvingly move at different speeds in circular paths over the bottom plate of the mill, thereby grinding the material pinched between their V upright and lower faces and the bottom of the mill. l

The housings of the mills shown in Figs. 3 and 4 may be composed to advantage of a plurality of cylindrical shells 71 2, 71.3, M, 71.5, hi3 provided with and interengaging each other by oflset sleeves n3, n4, 125; in this way-the disassemblage of the mill housing is facilitated for inspection and repair, for instance when worn grinding rings must be removed and replaced by new or reground ones.

Instead of suspending the grinding mill by means of chains l3, l3 (Fig. 1) the mill may be yieldingly supported by a plurality of spaced springs 45, and brackets 46, i5 circumferentially attached to the mill housing, as seen in Fig. 4.

- I claim:

Mill for continuously grinding material in bulk comprising a drum shaped, vertically disposed grinding chamber, having a cylindrical impeller face and a bottom formed with discharge holes therethrough, means for feeding the material into said chamber, a plurality of grinding rings superposed upon each other, resting on the bottom of said chamber and being of smaller diameter than that of the impeller face, and of which alternate rings differ in theirdiameter from their mates, and means for bodily gyratlng said chamher-in closed cycles of movement transversely to its axis, so as to revolve said grinding rings relatively to the grinding chamber and in a direction of rotation opposed to that of the gyrating motion of the latter.

FRIEDRICH CONRADI.

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