US2589917A

US2589917A - Grinding mill

Info

Publication number: US2589917A
Application number: US58973A
Authority: US
Inventors: Zuckert Richard
Original assignee: L AND C HARDTMUTH Inc
Current assignee: L AND C HARDTMUTH Inc
Priority date: 1947-11-27
Filing date: 1948-11-08
Publication date: 1952-03-18
Anticipated expiration: 1969-03-18

Description

March 18, 1952 R. ZUCKERT 2,589,917

GRINDING MILL Filed Nov. 8, 1948 2 swam-swam 1 MVP/Jfif Rlcuaao Z UCKERT March 18, 1952 R. ZUCKERT 2,589,917

/ GRINDING MILL Filed NOV. 8, 1948 v 2 SHEETSSHEET 2 lm mfor Rmymao Z UCKERT Patented Mar. 18, 1952 GRINDING MILL Richard Ziickert, Chard, England, assignor of one-half to L. 6 C. Hardtmuth, Inc., Blooms: bury, N. J., a corporation of New Jersey Application November 8, 19 i8, S erial No. 5 8, 9 7-3 In Great Britain November 2?, 194? 11 Claims.

This invention relates to grinding mills, especially, though not restrictively, to mills for grindn raphite r se in t e nufa ure Of pencils.

Various forms of wet grinding mill are known for this purpose; for example in one form a grinding stone is superposed on, and rotated ecccntrically in relation to, a second grinding stone which is free torotateabout its own axis as a result of the friction between the contiguous surfaces of the two stones, the mixture of water withgraphite to be ground being fed axially through the upper stone and passing radially outwards between said contiguous surfaces. The output of this mill is small.

In another form, a'high speed mill, the grindingstones are coaxial, their contiguous surfaces are formed with corresponding grooves and ridges sothat in cross-section the grinding surface o f each stone'is of zig-zag configuration, one stone being fixed and the other rotated and the mixture of Water with graphite being fed in axially through the rotary stone.

In still another mill a plurality of grinding blocks are urged radially against the periphery of ,a-rotary grindstone, the graphite being fed to the contiguous surfaces of the blocks and stone through passagesformed in thevblocks. In yet another arrangement ah-rotary, grinding stone 1S te m d w n inte na f ungon c l rin i surface and is fitted on -to a correspondingly shaped fixed grinding stone, the mixture .of water .with graphite, beingfed axially through the rotary stone.

According to the present invention a grinding mill comprisesv a body presenting an inner peripheral grinding surface, a carrier arranged to .b rot ted with n the bo y a d a leas one grinding block disposed onsaid carrier so as to bes i eble rad ally wit res e thereto and ear against the innepperipheml lihdingsurface of the .body under the influence of centrifugal force, thejbody being arranged for the introduction thereinto of the material to be ground and for the egress of the ground material.

tis d si ab e theta plura i y of. gri din blocks-should be slidably mountedon the carrier which ay e xial y arra ed with res to the ably, is arranged eccentrically so that material lying in the spaces between adjacent blocks is subjected to pressure as it approaches the exit from the body.

The invention is illustrated bythe accompanying drawings in which:

Figure 1 is a partly sectional side elevation of one form of grinding mill,. the section being taken on the line I I, Figure .2;

Figure 2 is anend elevation thereof, as seen from the left, Figure 1, with the end plate .removed; V

Figures 3 and Aaresectional .end views onthe lines III-III- and IV?IV, respectively, Figure l; and V Figures 5 and-6 are diagrammatic viewsof .two arrangements for carrying flout the grinding of,

e.. g. graphite for use in the manufacture of ing-space latthe left-handend of the-body a,

Figural). Thediaphragm g is 'formedlwith an inlet passage 7' and anoutlet passageJcAF-igure 3)- communicating vwith the chambers (e and f, respectively.

Within the body a, at the side of the. diaphragm g remote from the chambers .ea'nd ,r a solid cylindrical carrier m (Figures 1 and 2 .is mcunted on the projecting end of .an v eccentric shaft n. carried in a bearing oKFigure 14),,the diameter of the carrier-m and the eccentricityof the shaft nbein'g such that the periphery of the carrier mand the inner periphery of the body a are tangential at the top of the latter. A'pla'te napplied to theend of the body a closes, in

saidbody, the grinding space, between said plate -,With the grinding space has "an fiijgu v clay, siliceous stone or the like to present a grinding surface and the carrier m is formed with recesses r to receive grinding blocks s of similar material. The operative face of each block may be of the same curvature as the inner peripheral surface of the grinding inset q (i. e. of the same radius as the inner peripheral wall of the body a) and, preferably, the leading end of said operative face is of smaller radius, as indicated at t, Figure 2, for a purpose which will appear hereinafter.

As shown in Figure 3, the inlet passage 7' to the grinding space begins at about 20 (in the direction of rotation of the body m) from the position where the periphery of the body m and the inner periphery of the body a are tangential to one another and has an angular extent of about 120 and the outlet passage extends for about 20 up to said position.

For use the inlet 0 is connected with a source of supply (not shown in Figures 1 to 4) of a mixture of water and graphite and the shaft n is rotated by means of a belt pulley u mounted thereon and driven from a prime mover, not shown. Centrifugal force acting on the blocks s as a result of the rotation of the carrier m causes said blocks to move radially outwards and bear against the inner peripheral face of the body a, and, on account of the eccentric movement of the carrier m within the body a the device acts as a pump and the arrangement is such that some of the graphite drawn through the inlet 0 and passage 7 into a space 1: between two adjacent grinding blocks s passes,,and is ground, be-

tween the operative face of the trailing block s and the inner peripheral surface of the inset q, passes to the succeeding space and is ground by the succeeding block s, and so on, the graphite being carried round gradually as the carrier m is rotated and being compressed as the volume of the spaces '0 is reduced, the pressure thus created serving to expel ground graphite through the outlet passages k and d. The entrance of the graphite to the operative face of a block s being facilitated by the space at t.

It has been stated above that the operative face of each block s may be of the same curvature as the inner peripheral surface of the body a. This indicates that in general there will be adequate surface contact between those two parts during the revolution of the body, but, as the pressure on the liquid increases during the second half of a revolution of the eccentric body it is desirable that the surface contact should be superior during said second half revolution, for whichpurpose the curvature of the operative face of each block should approximate as nearly as possible that of the inner peripheral wall of the body when the block is at about 45 in rear of the position at which said surface and wall ar tangential.

In order to ensure thorough grinding of the graphite repetition of the operation is desirable, for which purpose, shown by way of example in Figure 5, the inlet 0 and outlet d may be connected with a storage vessel w, in which the liquid mixture may be stirred to prevent precipitation and from which it may be drawn and passed again through the mill. Alternatively, as shown in Figure 6, a plurality of mills may be connected in series so that the output from one mill passes direct to the inlet of the next mill of the series and so on.

been carried round in a space 1) and thus escaped being ground) will, in time, be subjected to the desired grinding operation.

If desired the body a and/or the vessel w may be water jacketed but it will usually be found sufficient to cool the liquid as it passes to and/or from the vessel to or when a series of mills is employed as it passes from one mill to the next.

In some cases springs may be provided to ensure contact of the operative faces of the blocks 1' with'the inner peripheral surface of the body a so as to ensure that pumping action will commence as soon as the carrier m is rotated.

Although the inlet and outlet passages j and it provide for the entrance of the liquid into the grinding space, and its exit therefrom, in a direction parallel with the axis of rotation of the carrier m, such entrance and exit may be arranged in the radial direction, but the former is preferable as it enables the maximum grinding surface to be presented in a mill of any given size.

If desired, pressure... (positive and negative) means may be provided for facilitating the introduction of the material into, and its exit from,

the body a, such pressure means may be 00- ordinated with the rotation of the carrier so that impulses occur when spaces between adjacent blocks are opposite the entrance and exit passages.

A grinding mill constructed in accordance with this invention is adapted for operation at high speed, the graphite is not subjected to anything but simple grinding action, i. e. it is never subjected to beating, stamping or other impact as in some of the known mills and yet the improved mill has a greater output than the known forms of mere grinding mills.

I claim:

1. A grinding mill comprising a cylindrical body presenting an inner peripheral abrasive surface, a carrier mounted to rotate within said body about an axis eccentric to the axis of the body. at least one abrasive block mounted in said carrier and slidable radially with respect thereto so as to bear against the grinding surface under the influence of centrifugal force, and an inlet and outlet into the grinding space of the body located on opposite sides of a radial plane through the point of closest approach of the carrier to the body.

2. A grinding mill as claimed in claim 1 having a plurality of radially slidable blocks.

3. A grinding mill as claimed in claim 2, in which the inlet to the grinding space extends from about 20, in the direction of rotation of the body, from such point to about fromsaid point and an outlet extending through about 20 up to said point.

4. A grinding mill as claimed in claim 3, wherein the operative face of each abrasive block has the same curvature as the inner peripheral surface of the body. 1

5. A grinding mill as claimed in claim 4, wherein the leading end of the operative surface of each abrasive block is of reduced radius.

6. A grinding mill as claimed in claim 1, in which the inlet to the grinding space extends from about 20, in the direction of rotation of the body, from such point to about 140 from said point and an outlet extending through about 20 up to said point. r

7. A grinding mill as claimed in claim 6, wherein the operative face of each abrasive block has the same curvature as the inner peripheral surface of the body.

8. A grinding mill as claimed in claim 7, wherein the leading end of the operative surface of each abrasive block is of reduced radius.

9. A grinding mill as claimed in claim 1, wherein the operative face of the abrasive block has the same curvature as the inner peripheral surface of the body.

10. A grinding mill as claimed in claim 1, wherein the leading end of the operative surface of the abrasive block is of reduced radius.

11. A grinding mill as claimed in claim 1 in which said surface and block are of a material selected from the group consisting of hard porcelain, fire clay and siliceous stone.

RICHARD ziicKER'r.

REFERENCES CITED Number Number 6 UNITED STATES PATENTS Name Date Lucop Feb. 15, 1876 Corcoran Aug. 5, 1884 Hilton July 28, 1885 Pamphilon Jan. 23, 1894 Suttie Aug. 13, 1901 Wallace Feb. 11, 1902 Knapp Sept. 19, 1905 Besser Jan. 4, 1908 Arpin Oct. 20, 1928 Estey Feb. 22, 1949 Livermore Mar. 7, 1950 FOREIGN PATENTS Country .Date Sweden Apr. 17, 1934 The following references are of record in the 20 file of this patent: