US1176040A - Grinding-mill. - Google Patents

Description

H, L. DOHERTY.

GRINDING MILL.

APPLICATION FILED ocr.29.1909.

1,176,040. Patented Mar. 21,1916.

g lttmcaqcaz Henry Duh erTy, {Jvwawlfoz 7 -/ifl- 51 31 15 aftom uzx HENRY L. DOHERTY, OF NEW YORK, N. V

GRINDING-M ILL.

Specification of Letters Patent.

Patented Mar. 21, 1916.

Application filed October 29, 1909. Serial No. 525,386.

T 0 all whom it may concern Be it known that I, HENRY L. DOHERTY, a citizen of the United States, and resident of New York city, in the county of New York and State of New York, have invented certain new and useful Improvements in a Grinding-Mill, of which the following is a specification.

This invention relates to grinding mills and particularly to that kind of such mills commonly known as ball mills, in which the material is ground in a rotating cylindrical barrel containing balls or pebbles.

The object of my invention is to prov de an improved form of such mills in which latter the reduction of the material is performed by a rolling and crushing action of the balls rather than by the grinding action which accomplishes a large part of the reduction of the material in the commonly used types of ball mills.

Other important objects of my invention are the prevention of the excessive wear on the balls themselves due to their mutual grinding action such as they have in the ordinary type of ball mill, and the elimination of the necessity for screens in the mill itself.

To this end my invention comprises a rotatable grinding barrel having grooves whose diametral planes are at right angles to the axis of the barrel, grinding balls in each of said grooves, means for transferring material that has passed under one ball to the groove of the next ball, the material being introduced into that portion of said groove which is at the moment on the descending side of the grinding barrel, means for rotating the barrel, means for introducing the material to be ground into the grinding barrel and for Withdrawing the ground material from the barrel, as well as other features which arev fully set forth below.

In the accompanying drawing Figure 1 is a longitudinal section of my invention taken on a vertical plane through the line A B of Fig. 2. Fig. 2 is a cross-section of the mill on the line C D of Fig. 1 looking toward the discharge end of the mill. Fig. 3 is a partial longitudinal section on A B of the discharge end of the mill looking in the opposite direction to the view in Fig. 1. Fig. 4 is an elevation of the discharge end of the mill. Fig. 5 is a side elevation of one of the grooved, segmental blocks of which the lining is constructed, showing a ball resting in the groove. Fig. 6 is a cross-section of the same. Fig. 7 is a part elevation of the charging end of the mill showing the location of the feed chute, etc.

In the drawings, 1 is the grinding barrel or drum, 2 the adjustable fixed shaft of the same, 3, the lining of thedrum which is divided into a series of grooves, 4, 4, 4, etc. In the preferred construction of my invention the lining is made of segmental blocks 5, of hard burned or vitrified clay having grooves, 4 and curved faces to fit the inner surface of the steel shell 7 of the grinding barrel.

8 and 8 are roller bearings supporting the drum 1.

9 is a driving device, preferably a motordriven shaft 10, carrying a spur wheel 11, gearing with a circular rack 12, carried by the shell 7 of the drum 1.

13, is the feeding device which may be of any preferred type. as here shown, being a helical conveyor discharging into a chute 14, which in turn discharges into the first groove of the mill through a circular aperture 15, in the head 16, of the grinding barrel. A light cover 15' supported by the chute 14, or in any other suitable manner, covers the aperture 15 in head 16. thus preventing the escape of dust through 15.

The lower end of the barrel is closed by a fixed housing 17, having a circular opening in which the end of the drum 1, rotates. The drum does not bear in the housing 17,

but should make a fairly close fit with the housing in order to prevent dusting. The housing 17, also is provided with a manhole 18 which furnishes a means of access to the interior of the drum. An opening, 19. in the bottom of the housing permits of the ground material discharging from the last groove 4, to enter the casing of the screw conveyer 20.

The fixed shaft 2, of the barrel is supported in bearings 21 and 21' in the supports 22 and 22. A spur-wheel 23, keyed to the axial shaft 2, gears with the spur-wheel 24, carried by the shaft 25, of the hand-wheel 26. Holes 28 are bored in the web of the spur-wheel 23, and on the wheel 23 being rotated any one of the holes 28 may be caused to register with a hole 30. in the support 22. A pin 27 can be inserted through that one of the holes 28, which register with 30, into the hole 30, in the support 22, thus locking .a driving shaft 34. Keyed to the shaft 34,

are the pulleys 35, corresponding to the loose pulleys 31 on shaft 2. Belts 36, work on the pulleys 31 and 35. These belts carry a number of semi-circular blades 37, set perpendicular to the belt and of a diameter somewhat smaller than that of the grooves 4. The driving shaft 34:, is set at such distance from the fixed axis 2, that when the belts are in position on the pulleys 31 and 35,,the blades 37, project into their corresponding grooves. Supported by the brackets 32, are small chutes 38, one to each belt, which divert the material falling from the belts into the next groove toward the discharge end of the mill. The end of the shaft next to the feed end of the mill carries a spur-wheel 39. This meshes with an interior gear 40, carried by the head 16.

The method of operation of the mill is as follows: The motor being started, and a rapid motion of rotation having been communicated to the grinding barrel the material to be ground is fed into it through the chute 14, falling into the first groove ofcthe mill. .The rotation of the barrel carries the material under the first ball which, of course, rolls in the groove as the barrel is rotated, maintaining a position in the lower part of the grinding drum 1, under the influence of gravity. The material in the grooves offers a certain resistance to the rolling of the balls, and, as a consequence, there is a lateral displacement of the balls from the middle position relative to a vertical plane through the axis of the mill which they occupy when at rest. The ball acts as a roller, more or less, crushing the material. The centrifugal force developed by the rotation causes the particles of the material, after passing under the first ball, to be carried up well into the upper quadrant of the path of rotation of the drum until the tangential component of the force of gravity has become sufficient to overbalance the centrifugal force when the partially ground material falls away from the wall of the drum and tends to roll back into the lower quadrant. Instead of rolling back. however, it is intercepted by the blades or scoops on the belt of the first conveyer and carried by the belt to the other side of the axis of the drum.

and discharged into the first chute 38, which deflects the falling materialinto the second groove 4, on the descending side of the drum. The continued rotation of the drum,

as before, carries the material under the ball of that groove, and into the upper quadrant from where it falls onto the second belt, is again carried to the other side of the axis and deflected into the third groove. This action is repeated until the material now finely ground, is discharged from the last of the chute 19, in housing 17. From 19, the ground material falls into the conveyer 20, and is conveyed to storage or to screening apparatus. In the latter case, any material which is over the fineness required is returned to the feed conveyer 13, to be reground. With materials of different gravities, it is evident, that with the-same speed of rotation the materials will be carried to different heights before falling back to the lower part of the groove. To meet this condition, the fixed'shaft of the drum may be adjusted by operating the hand-Wheel 26, as before explained, until the conveyer belts 36, are in the proper position to take up the ma terial.

In the construction of my apparatus I prefer to use for the lining or grinding surface 3, of the drum 1, segmental blocks of vitrified clay, as already explained, and to make the grinding balls of the same material. It 1s manifest, however, that if for any reason preferred, both the lining 3, of the drum and the balls themselves'may be of metal, or the lining, 3, may be made of either vitrified clay or metal and the balls of suitably dressed flint pebbles of large size. It is highly advantageousihowever, to use the sectional construction described. With a sectional construction of the lining, any of the segmental blocks which may be broken or Worn out during the operation of the mill, may be easily removed and replaced with new blocks. With this construction, the lining may be maintained in good condition indefinitely by simply renewing small sections of the lining as they become worn with new blocks, and the necessity of entirely relining the drum on account of local wear avoided.

I have found that in the grinding of such materials as coke there is an excessive wear on metal grinding surfaces. As the renewal of these parts of the grinding apparatus involves considerable expense when they are made of metal,I prefer to use for them whenever possible, vitrified clay, as already mentioned. I have found that in the grinding of coke this material gives excellent re sults and when not subjected to'impact or grinding contact wears well and costs far less for renewals than metal. It is not possible to use this substance in ball mills of the ordinary type-because in these the balls are charged into the grinding drum in a tween themselves and to blows from tumbling about in the revolving drum. When made of fireclay this causes a rapid wear and disintegration of the grinding balls. In my present invention, however, this objectionable action is avoided by the fact that I do away with the violent abrading action that takes place between the balls and by isolating them in separate grooves prevent any abrasive action between the grinding surfaces. The balls simply roll in the grooves and are, for the most, always separated from actual contact with the walls of the grooves themselves by a thin layer of the material that is being ground. This is usually much softer than the vitrified clay of the grinding surfaces, so that the wear on the latter is reduced to a minimum.

Having described my invention what I claim is:

1. In a grinding apparatus, the combination of a rotatable drum having an interior grinding surface comprising circular corrugations, said corrugations being contiguous and the diametral planes of said corrugations being perpendicular to the axis of said rotatable drum, grinding balls in said circular corrugations, and a separate belt conveyer cooperating with each of said grooves for discharging ground material from that groove.

2. In a grinding apparatus the combination of a rotatable drum, having a plurality of grinding surfaces arranged circumferentially on the interior surface of said rotatable drum, a substantially spherical grinding body cooperating with each of said surfaces and adapted to make a rolling contact with the surface upon the rotation of said drum, a separately rotatable conveying means cooperating with each of said surfaces and actuated by the rotation of said drum for removing from that surface substantially all of the material thereon which has passed under the grinding body cooperating with that surface and for transferring the said material to the adjacent grinding surface.

.3. In grinding apparatus the combinationof a substantially horizontal rotatable drum, having a plurality of continuous concave grinding surfaces arranged circumferentially on the interior surface of said rotatable drum, a grinding body cooperating with each of said surfaces and adapted to make a rolling contact with the surface, the thickness of said grinding body being greater than the depth of the concavity of said grinding surfaces, an endless belt conveyer cooperating with each of said grinding surfaces and adapted to remove from that surface and transfer to the adjacent grinding surface the major portion of the material thereon which has passed under the grinding body cooperating with that surface, bearings for said drum, means for feeding the material to be ground to the first of said plurality of grinding surfaces, means for discharging the ground material from the last of said grinding surfaces and means for imparting rotation to said grinding drum. substantially as described.

4:. In a grinding apparatus the combination of a rotatable grinding drum, having a plurality of concave grinding surfaces arranged circumferentially on the interior surface of said rotatable drum, the said concave grinding surfaces having a semi-circular cross-section on a radial plane perpendicular to their diametral planes, a substantially spherical grinding ball cooperating with each of said concave grinding surfaces and adapted to roll on said surfaces upon the rotation of said grinding drum, bearings for said drum, means for feeding the material to be ground to the first of said grinding surfaces. means for preventing the material from one surface. after it has passed under the grinding ball cooperating with that surface, from again passing under said ball and for transferring the said material to the next adjacent surface toward the discharge end of the drum, in a position to pass under the grinding ball -cooperating with the said adjacent surface.

means for discharging the ground material from the last of said plurality of grinding surfaces. and means to cause the rotation of said grinding drum, substantially as described.

5. In a grinding apparatus the combination of a rotatable circularly corrugated grinding drum having an interior grinding surface, the diametral planes of the corrugations of said surface being substantially perpendicular to the axis of said rotatable drum and the cross-section of said corrugations on planes passing through the axis of said grinding drum comprising substantially an arc of a circle, approximately spherical grinding bodies cooperating with each of said corrugations and adapted to make rolling contact with the surface of said corrugations upon the rotation of said grinding drum, said grinding bodies being of greater diameter than the depth of said corrugations, bearings for said drum, an axial shaft extending through said drum.

but structurally independent of said drum.

means for removing from each corrugation and transferring to the adjacent corrug. tion the major portion of the material in that corrugation after said material has passed under the grinding body cooperating with that corrugation. said means being supported by the said axial shaft. means for feeding the material to be ground to the first of said corrugations. means for discharging the ground material from the last of said corrugations. and means for rotating said grinding drum. substantially as described.

6. In a grinding apparatus the combination of a rotatable circularly corrugated grinding drum having an interior grinding surface. a grinding ball in each of the corrugations of said surface adapted to make a rolling contact with the surface of the corrugations upon the rotation of said grinding drum. bearings for said drum, an axial shaft extending through. said drum but structurally independent of said drum, supports for said shaft, means for fixing Said shaft in'a fixed position in said supports,

brackets on said shaft supporting a second shaft located eccentrically in reference to said drum, pulleys on said axial shaftand on said second shaft, belts working on the cooperating pulleys of the respective shafts adapted to take up the material to be ground from one corrugation and transfer it to the next adjacent corrugation toward the discharge end of the drum, means for feeding the material to be ground to the first of said corrugations, means for discharging the ground material from the last of said corrugations, and means for causing the rotation of said grinding drum, substantially as described.

7. A grinding mill comprising in combination a substantially cylindrical, revoluble, drum, a lining for the shell of said drum, said lining having a plurality of contiguous grooves. the cross-section of each of said grooves on a plane passing through the axis of said ,drum comprising an arc of a circle in its middle portion. a plurality of substantially spherical grinding balls, one of said halls being located in each of said grooves and adapted to roll freely. therein upon the rotation of said drum, and a separately-rotatable conveying means for each of said grooves for removing from said grooves the material that has passed under the grinding balls of the respective grooves and transferring said material to the next adjacent groove. in position to pass under the grinding ball of said adjacent groove.

8. A grinding mill comprising in combination. a SllhStflTltlHlly cylindrical shell, a lining for said shell. said lining having a plurality of contiguous circular corrugations. said corrugations forming a plurality of runs for grinding bodies, a plurality of substantially spherical grinding balls, one of said grinding balls being located in each of said runs. and a plurality of scoops cooperating with each of said runs, the said scoops being adapted to enterth e run With which they are cooperating on the ascending side of the drum and remove from said run the major portion of the material therein which has passed under the grinding ball therein.

0. A grinding mill comprising in combination, a substantially cylindrical shell, a lining for said shell, said lining having circular grooves around the inner periphery of the same, a substantially spherical grinding ball co-acting wlth each of said circular grooves, a plurality of scoops cooperating with each of said circular grooves, the said scoops being adapted to enter that groove with which they are cooperating and remove therefrom material therein which has passed under the grinding ball inthat groove, and means for conducting the material removed from said scoops to the next adjacent groove toward the discharge end of said drum.

10. grinding mill comprising in combination a substantially cylindrical shell, a lining for said shell, said lining having circular grooves around the inner periphery of the same, a plurality of grinding balls, one of said grinding balls being adapted to roll in each of said circular grooves, an axial shaft extending through said grinding drum and having bearings without said drum, a plurality of scoops cooperating with each of said circular grooves, said scoops being supported in said drum by said axial shaft in such manner that said scoops will enter the groove with which they are cooperating on the ascending side of the drum and remove from said groove the major portion of the material therein which has passed under the grinding ball cooperating with that groove.

11. A grinding mill comprising in combination a substantially cylindrical shell, a lining for said shell, said lining having circular grooves around the inner periphery of the same, a substantially spherical grinding ball coooperating with each of said circular grooves, an axial shaft extending through said grinding dnum and having bearings without said drum. means for fixing said axial shaft in said bearings, a plurality of brackets fixed to said axial shaft, a driving shaft supported by said brackets, a plurality of scoops cooperating with each of said circular grooves, said scoops being actuated by said driving shaft and adapted to enter the groove with which they are cooperating and remove from said groove the major portion of the material therein which has passed under the grinding ball in that groove.

12. A grinding mill comprising in comblnation an outer shell, a hiring for said ,shell, said lining having a plurality of circular grooves around the inner peripheryof the same, a plurality of grinding balls, one of said grinding balls co-acting with each of said circular grooves, an axial shaft extending through said grinding drum and having bearings without said drum, means for clamping said shaft in a fixed position,,

a plurality of scoops mounted on each of said belts, the said belts being supported in such manner that the scoops of each belt will successively enter the groove with which they are cooperating and remove from that groove the ma]or portion of the material thereon which has passed under the grinding ball co-acting with that groove.

13. A grinding mill comprising in combination a substantially cylindrical drum, a head closing one end of said drum and attached to said drum and a fixed housing closing the other end of said drum, a lining for said drum, said lining having a plurality of circular grooves around the inner periphery of the same, a plurality of grinding balls, one of said grinding balls coaeting with each of said circular grooves, an axial shaft extending through said grinding drum and having bearings without said drum, means for fastening said shaft in a fixed position, a plurality of brackets fixed to said axial shaft, a driving shaft supported by said brackets, a plurality of endless belts, one of said belts eo-acting with each of said grooves, said belts being supported by said shafts and actuated by said driving shaft, a plurality of scoops mounted on each of said belts, the said belts being supported in such manner that the scoops of each belt will successively enter the groove with which they are cooperating and remove from said groove the major portion of the material therein which has passed under the grinding ball cooperating with that groove.

14. A grinding mill comprising in combination a substantially horizontal grinding drum having an interior circularly grooved grinding surface and grinding balls in the grooves of said surface, and means for conveying material from groove to groove of said surface, said conveying means comprising an axial shaft extending through said grinding drum and having bearings with-- out said drum, means for fastening said shaft in a desired fixed position, a plurality of brackets fixed to said axial shaft, a driv- I ing ball cooperating with that groove, a plurality of chutes, one of said chutes co-acting with each of said belts to receive the material removed by said belt and conduct the said material into the groove adjacent to the groove with which the said belt is co-acting.

15. The combination of a grinding drum having a peripherally grooved interior grinding surface and a grinding ball in each of the grooves of said surface, and convey ing means co-acting with each groove of said grinding surface and adapted to move material from groove to groove. said conveying means comprising an axial shaft extending through said drum but structurally independent thereof, supports for said axial shaft, means for clamping said axial shaft in a selected fixed position, a plurality of brackets fixed to said axial shaft, a plurality of individual conveyers, one of said conveyers cooperating with each of said grooves and being adapted to transfer material from that groove to the next adjacent groove toward the discharge end of said drum, said individual conveyers being supported from said axial shaft and being adjustable in position by rotating said axial shaft, a driving shaft supported by said brackets, said driving shaft being substantially parallel to said axial shaft and adapted to drive said individual conveyers.

16. A. grinding mill comprising an outer drum of substantially circular cross-section, a lining for said drum, said lining having a plurality of contiguous circular grooves, a plurality of grinding balls adapted to roll in said circular grooves, and conveying means cooperating with said grinding drum, said conveying means comprising a shaft mounted axially within said drum. means independent of said drum for varying the angular position of said shaft, a driving shaft substantially parallel to said axial shaft and supported within saiddrum. a plurality of conveyers supported by said shafts and adapted to cooperate with said grooves to move material from groove to groove, said conveyers each comprising a loose-pulley mounted on said axial shaft, a tight-pulley in alinement with said loose pulley mounted on said driving shaft and conveyer members operated by said pulleys.

Signed at New York city in the county of New York and State of New York, this 28th day of October, A. D. 1909.

HENRY i l. DUHERTY.

Witnesses THos. I. CARTER, C. B. GILBERT.

@opies of this patent may be obtained for five cents eacmhy addressing the "Commissioner of Patents, Washington, D. G.

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