US1014383A - Crushing-rolls. - Google Patents

Description

Patented Jan. 9, 1912.

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onusnme ROLLS.

Patented Jan. 9, 1912.

APPLICATION FILED 1113.25, 1911 2 SHEETS-SHEET 2.

nZQanf/OI fife/1977526272 512 azee M @WM, m mw JEREMIAH S. FRAZEE, OF NEW YORK, N. Y.

' QRUSHING-ROLLS.

To all whom it may concern:

Be it known that I, JEREMIAH S. FRAZEE, a resident of the borough of Brooklyn, city and State of New York, have invented a certain new and useful Improvement in Crushing-Rolls, of which the following is a full and true specification, reference being had to. the accompanylng drawings, wherein.

similar letters refer to like parts in the several views.

' My invention relates to improvements inf crushing rolls for the reduction or granulation of ores or other materials, and more particularly to improvements for maintaining the' crushing surfaces of such rolls parallel.

It consists in means for increasing the efficiency of crushin rolls, by equalizing the Wear across the aces of the roll-shells, and also by overcoming practically all end thrust of the roll shafts upon their bearings, thus greatly increasing the useful effect of the power employed in operating the rolls.

An important advantage of crushing rolls which, aside from their mechanical simplic- 1ty, has caused the1r wlde use as a means.

for crushing various materials, consists in the fact that when carefully operated, they produce a maximum granulating effect upon the material undergoing crushing, and a minimum pulverizing or sliming effect. In the case of many ores, this is a vital-advantage, since the degree of success of a subsequent gravity concentration often depends upon the proportion of the valuable mineral in an ore, which remains in a distinctly granular form after it has been crushed fine enough to free it from its attendant ganue minerals.

As hereto ore designed and operated the efficiency of rolls has been exceedingly low by reason of the irregular wear of their roll faces. In crushing coarse material, 6. 6. particles from 1 to 12 in diameter, down to i in diameter, this is not so serious a matter as in crushing finermaterial since in the former case the roll-surfaces must be kept fairlywell apart and the ratio of the sectional area dueto irregular wear to the total areal opening between the rolls, is less than incrushing fine material. .Hence for coarse material, a very closely regulated feed isnot so essential as for fine material. In the latter case, the crushing surfaces must be run quite close together, in some cases Specification of Letters Patent.

Patented Jan. 9, 1912.

Appllcationfiled February 25, 1911. Serial No. 610,910.

almost touching, and in this position it is evident that any irregular wear shown by the clipping? groovmg or corrugating of the roll-surfaces permits a considerable proportion of the particles in the feed-stream which enter the depressions to pass between the rolls without being crushed. The capacity of the rolls, measured by the amount of under-sizeor finished product, obtained when they are used for fine crushing is thus greatly reduced, as well as their crushing efficiency, measured by the power consumed to operate them in relation to the amount of finished-product obtained.

As rolls have heretofore been operated it has been practically impossibleto feed as much material at the very edges of the rollshells as at their centers. Ridges quickly form under these conditions, usually at the diagonally opposite edges of the roll-shells and these ridges prevent the crushing surfaces from approaching as closely as the requirements of the size reduction of the material undergoing crushing may demand. It then becomes necessary to stop the crushing operation and to remove the ridges either by machining them off, or else by grinding them down by means of an emery or carborundum block. This involves not only loss of crushing efliciency but also loss of time in the use of the rolls, expense in truing the, roll-surfaces, as well as a wasteful use of the roll-shells. I have found that by making one roll-shell longer than the other, so as to enable flanges to form gradually upon the longer roll-shell by the abrading action of the feed-stream, and by feeding a heavier stream of material at the sides of the faces than at the center of the shorter roll it becomes possible to entirely prevent any ridges from forming at the edges of the rolls. Irregular wear of surfaces of crushing rolls introduces also another serious difliculty. When out of parallelism along portions'of their surfaces, rolls tend to exert a certain component of the crushing pressure at right angles to the diameter of the rolls, or in the direction of the axis of the roll-shafts. This produces an end-thrust upon the roll-shafts, which transmit it by means of collars to their bearings, causing them to heat and the shafts to cut, thus abreducing the crushing efficiency.

I have found that by overcoming ridging of the roll-shells and by maintaining the roll surfaces parallel, the tendency'of the roll-shafts to move endwise in their bearings can thus be largely prevented. VVhatever tendency of the, rolls to shift their po' sitions endwise may still remain, due to irregularities of adjustment or of operation,

I can be best overcome by means of the flanges upon the longer roll-shell. By carrying the feed-stream a slight distance beyond each end of the unfianged roll-shell, a certain small amountof material undergoes crushing between thesides of the flanges and the two ends ofthe roll-shell. The effect of this is to prevent the escape of material from the ends of the roll by means of the flanges while it is undergoing crushing. The amount of crushing performed bythe sides of the roll faces, and their consequent wear, are thus under :control. Moreover, the end pressure exerted by the material between the flanges and the ends of the roll being equal and in opposite directions, thus balance, and the two roll shells, as well as their shafts, are held in the same relative positions while subjected to the crushing operation. The flanges thus perform a double function.

By my invention, which is especially concerned with the use of rolls for fine crushing, I am able to so control and adjust the wearing power of the feed-stream passing between the roll-shells as to entirely overcome any irregularity in the wear of the roll-surfaces, as well as practically all end thrust upon the bearings of the roll-shaft. Moreover by maintaining the roll-surfaces accurately parallel, I am able not only to greatly increase the crushing efiiciency of the rolls, but also to extend their use as a means of fine granulation far beyond the limit to which it has heretofore been considered possible to apply them.

In the accompanying two sheets of drawings, Figures 1 and 2 show in plan and sectional elevation crushing apparatus embodying my improvements and adapted to carry out my improved methods. Figs. 3 and 4 are enlarged end and side views ofthe discharge end of the feed-tray showing the means whereby the thickness of the sheet of material fed to the rolls may be varied and controlled. Figs. 5 and 6 illustrate in front and side views a modified feeding device. This is a roller-feed, and is provided with a feed-gate so constructed that the thickness of the difi'erentparts of the sheet of material to be crushed may be independently regulated.

Referring to the apparatus shown in Figs. 1 to 4, the numerals 1 and 2 represent two opposing roll-shells, which are centeredupon cores mounted. upon the shafts 3, 4. One of the roll-shafts 4, is held in bearings 51, supported by the ' frames 5, 6. The other roll shaft, 3, is held in movable bearings, 52,

retaining upon the feed-tray a layer of which slide in guides in the frames 5, 6. The position of thebearings 52 is adjusted by means of the screw bolts, 7 8, which permit them to be moved back and forth in exact unison, by means of sprocket wheels between the rolls. When in operation the opposing roll-shells are made to revolve in opposite directions by means of the driving pulleys 10, 11, keyed to the shafts 3, 4, and belted to an outside source of power.

As an aid in neutralizing the end-thrust of the roll-shafts upon their bearings and to prevent ridges from forming upon the edges of the shorter roll, I make use of flanges upon one of the roll-shells as shown in Figs. 1 and 2. Here one of the roll-shells, 1, is made to revolve betweenflanges 12 upon the other. roll-shell 2. The flanges upon rollshell 2 may either be attached thereto, or preferably formed upon it by making the roll-shell 2 longer than 1.

' The increased efiiciency which I have been able to obtain from crushing rolls by my invention, consists partly in the means employed for controlling the dimensions of the feed-sheet, not only in its width by means of flanges upon one of the rolls, but mainly in its thickness at various points across its width. The exact design of the feed mech-. anism which may be used for this purpose can be widely varied, but I have shown in Fig. 2, a type of feed-apparatus which I have found to be preferable in carrying out the purpose of my invention. Here the material to be crushed is fed to the rolls from a convenient hopper, 16, which is provided with a gate, 17 at its lower end, to control the amount of the material withdrawn. Below the hopper is an inclined feed-tray, 18, which is hinged at its rear end at 19. It is held at its discharge end by means of a con necting rod, 21, to the arm, 22, which in turn is hinged or flexibly connected at its rear end to the cross-bar 23., The arm 22, is raised and dropped rapidly by means of a rotating cam, 25, so as to exert a jarring or bumping action upon the end of the feed-tray, 18. The length of the drop, and therefore the effect of the bumping action is regulated by means of the adjusting screw, 26. The bottom of the feedtray, made of thin steel, so that the material will slide freely upon it. -The end of the feedtray is provided with an angle iron, 28. By the 18, is preferably material to be crushed, this angle iron prevents rapid or irregular wear of the surface of the feed-tray. Its main object, however, is to provide a dam or upright lip, over which the feed material is discharged in a regulated and controlled stream 'by the bumping act-i011 which is imparted to the feed-tray. I have found that as rolls are usually fed, even when great care is taken to secure a feed-sheet of uniform thickness, the roll-shells will groove and wear more rapidly at their centers than at their ends. One reason for this is that the friction of the material upon the sides of the chute or spout leading from-the feed-hopper to the rolls, retards the flow along the outer edges of the feed-stream so that the central portion of the roll-shells actually receives and crushes a larger amount of material than the ends, and shows the effect in greater wear. Another reason may be found in the tendency of an ore-sheet subjected to a crushing pressure to flow somewhat more in one direction than in another. Being densely compacted at the center of the rolls and having a somewhat greater freedom of motion at the ends of the rolls, the reduction of the area of the feed-sheet while undergoing crushing between the roll-shells doubtless causes a somewhat greater damming back, or flow of the material at the center of the rolls than at their ends. The effect of this is also shown in greater wear at the center of the roll-shells than at the ends and consequent grooving.

I have discovered that all irregular wear of roll-shells can be entirely overcome by feeding a graduatedly heavier stream of material along the sides of the roll faces than at their centers, so regulated and controlled, as to overcome the normal irregularity of the wear of roll-shells when they are uniformly fed. As shownmore clearly inFigs;

3.and 4, the projecting side of the angle iron 28, which forms thelip of the feedtray, 18, is cut down near its two ends in such-a way that the feed-sheet which is discharged over its edge, has a gradually increasing thickness toward its ends. I have also found it desirable to regulate both the upper as well as the lower contour'of the feed-sheet in giving it such a sectional shape which shall exert an equalized abrading power upon the rollsurfaces across their widths, and thus maintain them in paral- 30, as shown in Fig. 3. The shaded area in v Fig. 3 shows the approximate cross section of the feed-sheet as it is discharged from the feed-tray into the rolls, in carrying out the purpose of my invention. The exact cross section will vary with the hardness of different materials to be crushed.

It will be evident to those skilled in the art that both the method and the particular details of my invention, may be applied to widely different types of feed-apparatus in accomplishing the'purpose of my invention. Feed apparatus applied to crushing-rolls may in general be divided into two classes, viz.: those which employ a feed-tray or spout to lead the material from the feedhopper to the apparatus being fed, and those which are without such a feed-tray. In the first class is included the. shakingfeeder, one form of which is described above, the scraping feeder, and the plunger feeder, etc. These differ mainly in the manner of discharging the feed-material from the feed-tray. In the shaking-feeder the feed-tray is given a rapid longitudinal motion as a whole instead of a jarring or bumping motion as shown in Fig. 1. In the scraping-feeder the feed-tray is also moved back and forth, but the feed-material is progressed lengthwise of the feed tray by reaction againsta plate or bar maintained in a stationary position just above the surface of the feed-tray. In the plunger-feeder the feed-tray or chute is stationary, and the given a reciprocating motion. In the above class of feed apparatus, the end of the feedtray may in each case be provided with a dam or upright lip, as well as a guide plate resting upon the surface of the feed-sheet for the purpose of a close control of the feed-sheet cross-section at its point of discharge, as shown more clearly in Figs. 3 and 4.

That class of feed-apparatus which does not employ a feed-tray or spout leading from the feed-hopper is chiefly illustrated by the roller-feedQ In Figs. 5 and 6 I have shown my invention applied to such a roller feed. In the figures, 35 designates material in a hopper 36, located on the feed roll 37 journaled in bearings 38 and adapted to be rotated by the pulley 39. A gate 42 is located on the roll and is adjustable vertically by raising or lowering the supports 40. The

so as to cooperate with the curved edge of the gate 42 and roduce the desired regulation of the feed sheet. In some cases it may be advantageous to make the lower edge of the gate straight and regulate the cross section of the feed sheet by the curved surface of the roll 37. It will be evident from the above that the principle of my invention may be applied to widely different types of feed-mechanism. I do not, therefore, desire to limit my invention to any particular design or type of feed-mechanism.

I am aware that the use of flanged rolls has heretofore been proposed and tried in practice, but the attempts to secure the advantages claimed for them have heretofore failed, by reason of the fact that they have never been operated in connection' with feeding mechanism adapted to feed a sheet of variable thickness so as to insure a proper distribution of the material at the sides of the faces and against the flanges, thus giving a balanced action and preventing irregular wear of the roll surfaces. Unless the roll surfaces can be maintained parallel, the roll-shafts cannot be freed from endthrust by the use of flanges upon the rolls alone. By employing my improved apparatus and method I have been able to obviate both uneven wearing .and end thrust and I have been able to use roll-shells having a thickness of wall 35;", and by retaining their crushing surfaces perfectly parallel, to wear them down to y thick without any machining or re-surfacing of the roll-shells whatever. In this. way I am able to greatly increase the crushing efliciency of the rolls and at the same time to increase their capacity as well as to reduce the cost of operating them.

In order to more clearly define the scope of my invention, it may be desirableto explain that what is known as choke crushing differs from free crushing mainly in feedinga heavier sheet of material to the rolls, with the object of causing a considerable amount of the work to be done by the crushing pressure of the particles upon themselves. In free crushing a thinsheet of material is fed to the rolls with the object of limiting the diameter of the crushed particles as nearly as possible to the opening maintained between the opposing roll-surfaces. Choke-crushing has the advantage of producing a larger amount of finished product or under-size than free crushing, and is of especial value where quite fine crushing is required, and where at the same time it is not desirable to produce so large a proportion of pulverized or powdered material as is sought to be accomplished by the use of grinding machines. It is obvious that unless the roll-surfaces can be maintained accurately parallel, the advantages of chokecrushing for fi'ne size reduction by means of rolls are largely nullified and prevented.

By my improvements in the design and method of operating crushing rolls, I am able to employ choke-crushing in those cases where fine size reduction by means of rolls is desirable, and by these means I am able to extend the use of crushing rolls far beyond the point to which it has heretofore been considered feasible or 7 possible to apply them.

I claim as my invention:

1. In crushing rolls, two 0 posing rollshells one of which is provide with flanges at its ends inclosing the ends of the opposing roll-shell, in combination with means for feedin between said roll-shells a sheet of materia of greater thickness at its edges than'at its center, said flanges serving to guide and confine an increased amount of material adjacent to the flanges, for the purpose specified.

2. In crushing rolls, two opposing rollshells one of which is provided with flanges at its ends inclosing the ends of the opposing roll-shell, in combination with means for feeding between said roll-shells a sheet ,of material of greaterthickness at its ed es than at its center and of a greater wi th flanges, for the purpose specified.

3. In crushing rolls of the kind described, the combination of two opposing roll-shells one of which is provided with flanges at its ends inclosing the ends of the unflanged roll, with means for feedin between said rollshells a sheet of material of greater thickness at its edges adjacent to said flanges than at its center, said means comprising a feed-tray provided at its discharge end with an upright lip-dam'of varying height, for the purpose specified.

4. In crushlng rolls of the kind described, the combination of two opposing roll-shells one of which is provided with flanges at its endsinclosing the ends of the unflanged roll, with means for feedin between said rollshells a sheet of material of greater thickness at its edges adjacent to said flanges than at its center, said means comprising a feedtray provided at its discharge end with an upright lip-dam of varying height, and a guide-plate in said feed-tray arranged to rest upon the surface of the feed-stream.

5. In crushing rolls, the combination of two opposing roll-shells, means for feeding a larger amount of material along the sides of the faces of said roll-shells than at their centers, means for extending the edges of the feed-stream beyond the ends ofone of said roll-shells and. means for causing the exposed edges of said feed-stream to be acted on by a crushing pressure exerted against the ends of said roll-shell, for the purpose specified. 4

6. In crushing rolls, means for maintaining the faces of two opposing roll-shells par- 5 allel while they undergo wear, which consists in a feed-stream, charged between said roll-shells, having a greater thickness at its edges than at its center, whose edges extend beyond the ends of one of said roll-shells and which are acted on by a crushin pres- 10 sure exerted against the ends of s'ai r011- shell, substantially as described.

JEREMIAH S. FRAZEE. Witnesses:

GUSTAV BERGSTROM, S01. A. BARR.

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