US1723055A - of spbiktgpietd - Google Patents

Description

R S CHLIN ATT ION MILL Filed July 5, 192'? Aug. 6, 929.

Patented Aug. 6, 1929.

UNITED STATES PATENT OFFICE.

ROBERT S. MECHLEN, OF SPRINGFIELD, OHIO, ASSIGNOR TO THE BAUER BROTHERS COMPANY, OF SPRINGFIELD, OHIO, A CORPORATION OF OHIO.

ATTRITION MILL.

This invention relates to grinding plates for attrition mills, it particularly relating to that type ot plate which has ribs extending on radial. lines and other ribs extending on chordal lines.

The object of the invention is to so arrange the ribs as to avoid sinnilta-neous registration at any one time of the major portion of the ribs of opposed grinding plates to thereby reduce friction between opposing 'ilates and enable a larger quantity of material to be ground to a liner degree with thesame amount of power, or less: also to distribute the wear upon the plates in a more uniform manner and provide for a more etl cctive grlnding areajand also to allow for a free flow of ma terial between the plates.

To that end, the invention consists in arranging the grinding surfaces into sectors, with each sectorprovided with a. plurality ot series of parallel ribs which extend along chordal lines and a plurality of series of ribs which extend along radial lines, with the chordal ribs of one series in staggered rela tion with those of another series, and with each series of radial ribs so disposed in relation to the other series that these radial ribs will be in more or less staggered relation to the ribs of an opposing sector at all times and especially when opposing sectors are in completc registry.

A "further object of the invention is to provide an outer circumferential rib of zig-zag or saw-tooth form to reduce the friction adjacent the outer periphery of the grinding plates, and. to also impart a final reduction to the material.

In the accompanying drawings:

Fig. 1 is an elevation of the working face of a portion of a grinding head equippedwith my improved. plates.

Fig. 2 is an elevation of the working face of one of the plates showing in dotted lines an opposing plate in registry therewith to disclose the relation oi the ribs when oppos ing plates are in registry.

Referring to the drawings. 1 represents a portion of the grinding head of an attrition mill. For manufacturing reasons, the grinding surfaces of these heads are in the form of a series of platessecured to the heads. One of these plates is shown complete at 2, and

3 and 4; represent portions of other adjacent plates. The ribs are so disposed on the plates that when the plates are all assembled on a head the grinding surface is divided into a series of sectors in which the chordal ribs of each sector are in parallel planes. For instance, referring to Fig. 1 of the drawings, there are shown three complete sectors indicated at a, b and c and portions-of two other sectors (Z and 6. Each individual plate contains one complete sector and portions of two other sectors, as shown in Fig. 2 in which the sector 6 is shown complete while one-half only of each of the sectors a and c are disclosed, adjacent plates forming the other half of each of these sectors a and 0. Each sector is provided with two series of ribs 5 and 6 arranged in parallel planes butxwith the ribs 5 of one series in staggered relation to the ribs 6 of the other series. Each of these ribs 5 and 6 extends on a line which forms a chord of a circle whose center is the center of the Each sector also has a plurality of rows of radially extending ribs arranged different distances from the center andextending between the ehordal ribs, those rows on one side of the sector being indicated at 7 and those on the opposite side at 8. The ribs ofeach row are arranged varying distances apart. For instance, the ribs 7 of the first lower-most row in the present case are so separated that the pockets between them decrease in width progressively in a clock-wise direction while the ribs 8 of the lower-most row are similarly arranged. In the neXt'row above, the width of the pockets formed by ribs 7 increase progressively in a clock-wise direction as do also the width of the pockets formed by ribs 8. In the next row outwardly, the pockets formed by the major portion of the ribs 7 decrease in a clock-wise direction as do the pockets formed by the mag or portion of the ribs 8. In the latter row, however, this rule does not hold good as to the two outer pockets in each row, but the widthsof these pockets nevertheless vary. The two outer-most rows of ribs 7 and 8 are likewise disposed at varying distances apart. By this arrangement, the majority of the radial ribs of opposing sectors will at all times be more or less in staggered relation and this will be particularly true when two opposing sectors are in complete registry as shown in Fig. 2.

Each plate also has an outer circumferentially extending rib 9 which is of a zig-zag or saw tooth form as shown.

The result of this construction is illustrated in Fig. 2 in which itwill be seen that when two opposing plates are in exact registry the chordal ribs 5 and 6 of opposing sectors will occupy the position shown in full and dotted lines, with no two opposed ribs in registry with each other. The same thing is substantially true of the radial ribs as it will be seen that-the major portion of these ribs are completely out ofregistry or only partly in regisfaces leading to the periphery of the heads and the material is fed to the heads through a central eye in one of the heads and is thrown outwardly by centrifugal force, the material pass ingfrom pocket to pocket formed by the This arrangement of ribs, therefore, not only reduces the friction caused by the .materialbetween opposing ribs, but also allows for a more uniform flow of the material outwardly to the periphery of the-heads be- I cause of the fact that it eliminates the periodic cessation of flow which exists in those grinding heads in-which there is a periodic complete registry of all the ribs of opposed grind- .ing surfaces, which has the effect, it will be understood, of checking the flow of material when such complete registry takes place.

I 7 It will be understood that in the operation ,ofgrinding headsof this character, one or both of the heads revolve and the chordal A0 and radial ribs of opposing heads co-act with a shearing action to reduce the material.

Having thus described my invention, I claim:

1. In an attrition mill, a grinding head having a grinding surface provided with ribs positioned to divide the surface into sectors, a plurality of series of parallel chordally eX- tending ribs on each sector, with the ribs of one series in staggered relation with the ribs of an adjacent series, and av plurality of series of substantially radially extending ribs on each sector so disposed that the radial ribs of one series will be in staggered relation with the ribs of an opposing similarly formed sector when said opposing sectors are in registry.

2. An attrition mill, a grinding head having a grinding surface provided with ribs positioned to divide the surface into sectors including a plurality of series of substantially radially extending ribs on each sector so disosed that the radial ribs of one series will Be in staggered relation with the radial ribs of an opposing similarly formed sector when said opposing sectors are in registry.

3. An ,attration mill, a grinding head having a plurality of segmental plates, saidplatcs being .of uniform construction and provided with ribs positionedto divide the surface of the head into sectors, ear-h sector having two series of parallel chord-ally eztending ribs with the ribs of one series in staggered relation with the adjacent series, each. sector also having two-series of substantially radially 0:;-

In testimony whereof, I have hereunto set my hand this 1st day of July, 1927.

ROBERT S. MECl-ILIN.

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