US2249364A - Method and apparatus for size reduction - Google Patents

Description

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. METHOD AND APPARATUS FOR SIZE REDUCTION Filed Aug. 29, 1936 3 Sheets-Sheet 1 ,Eig-L n #W20 v1 .zum

July15,f1941. Ic. F. 056005 Y 2,249,364

METHOD AND `l*.11"RA'IUS FOR SIZE REDUCTION Filed Allg. 29, 1935 3 Sheets-Sheet 2 -EfJg-f?. 1 h 10 131415,111 711)7` 71161051/2/7??? 4 I "l -l /II/ L :1i IH 16 17 574mg 6V 420 el A 1f Ii l 4 Y .im i1 7 15 59 if 57 56155557 y .July 15, 1941. c. F. sGooD A 249,364

METHOD AND APPARATUS FOR SIZE REDUCTION Filed Aug. 29, 1936 1519.5. W'JV yf/f n i 5h15?! f5'. W 15@ 7g' 1 f 153 W l n j L 31 1I 76 5 91 Wmgnzn 3Q 3 110m WEI/99 g5 7"7- iP-10Q jgg -93 50 Cr MAIN 78 M01-0R RELAY u,

I 15J/yeah?? 134)' 130 'ialrydyaoci A y A y 7% 135 y, 148 AWA/11mm, l' 5S?) R f 3 Sheets-Sheet 3 Patented July 15, 194%1 Y .uNirED STATES PATENT voi-rics REDUCTION Charles F. Osgood, Claremont, N. H., assignor to Sullivan Machinery Company, a corporation of Massachusetts Application August 29, 1931s. serial No. 98,549

2 0 Claims. (Cisa-9) s My invention vrelates to mills andmore particularly` to mills having controlling apparatus associated therewith for 'preventing choking thereof.

Certain forms of size-reducing apparatus provide, when fed under close control,'quite elcient size reduction, but, unless the rate of feed is rigorously regulated, the mills will either tend to clear themselves of material undergoing the process Iof reductionand occasion excessive wear on the size-reducing media and the mill chamber,

or', on the other hand, tend to choke and rst lose eiilciency and then entirely cease to functionif this process is too long continued. It is an obf -ject of my invention to avoid both the difficulties mentioned. This can be accomplished, as demonstrated in the diierent embodiments oi my invention hereinafter disclosed, described and claimed, in different ways. size-reducing action may be speeded up for the purpose of offsetting a tendencyy to choke, due to the ingress of material at a rate in excess oi' the previous grinding or size-reducing rate at which The intensity oi.' theof materlal'within the mill in accordance with f I the load upon the driving motor.' It is stil1 a further object oi my invention to provide an improved method of regulating the operation of a milling apparatus by varying the intensity thereof automatically in accordance with the-quantity of material within the mill. Other objects and advantages of my invention, from both its method in which one or the illustrative embodiments of the mill was operated. This involves either an means for merely increasing the rate at which the mill is driven. Whenfeed rate decreases, a reduction in mill speed or. grinding rate will be called for. Another mode of possible procedure is to throttle varlably, as it were, the rate of material ingress into the size-reducing chamber, and

to control the eil'ective area of the material ingress passage automatically in accordance with the load within the mill, cutting down the ingress areawhen the load within the mill chamber tends to become too great, and increasing such area when the load within the mill chamber falls below a desired minimum. It is another object of my invention to provide an improved milling apparatus having controlling means regulating its rate of milling in accordance with the quantity of material therein. It is still another object oi my invention to provide an improved apparatus for regulating the intensity of the sizefreducing action in a mill, while maintaining the number in cycles of operation per time unit constant, and thereby to control the output of the mill to prevent material deviations from optimum size-reducing conditions therein. Itisstill another object of my invention to provide an. improvedsizereducing apparatus having a driving motor and provided with means for regulating the quantity the invention is incorporated and designed to Y operate in accordance with certain method phases of my invention; i

. Fig. 2 is a side elevation of the mill shown inw Fig. 1;

Fig. a is a section through the mili approxi-- mately on the planes oi the section line 3-3 of Fig. 4, with some parts shown in elevation Fig. 4 is a vertical sectional view on the planes of the section line 4-4 of Fig. 3;

Fig. 5 is a fragmentary section on the vertical plane 'oi the line 5-5 of Fig. 4;

Fig. 6 is a vertical sectional view showing a modified embodiment of the invention; and

Fig. 'l is a wiring diagram showing a system applicable to either the apparatus of Figs. 1 to 5 or the apparatus of Fig. 6.

Referring iirst to the form yof the invention illustrated in Figs. l to 5, and of which a diagrammatlc representation of the circuits isvcontained in Fig. 7, it will be noted that a size-reducing apparatus, generally designated I. has a primary drive pulley 2 suitably connected by power transmission means, herein in the ,form of a belt 3, with'a main driving motor 4, which is shown only in the diagrammatic view o1' Fig. 7. The mill I comprises'a base I upon which a suitable frame structure 6 is supported; and, in bearing means l and 8, carried by portions of the frame structure 8, is a drive shaft 9. to which there is suitably iixed the drive pulley 2, which is preferably made lof heavy construction, so that it may also perform a flywheel function. Thev other-v end of the frameI 5 herein provides a. mounting for a size-.reducing mechanism proper which #is generally designated ill.l Within a chamber II formed by a portion of the frame 6 and suitably closed bya cover plate l2, there is supported for oscillatory movement a size-reducing-chamber-providing element I3 supported by suitable pivoting means, herein in `the Aform of a stub shaft I4 journaled in a bearing I5 in the cover plate I2 and a rock shaft I5 lournaled at I1 in the frame 3 and having an outboard bearing I8 in another portion of the frame 3. A depending arm I9, forked at its lower end to provide a mounting for a pin 20, is secured at 2| to the rock shaft I6, and is adapted, upon the transmission of swinging movement thereto, to rock the rock shaft I6 and the supported chamberforming element I3.

The chamber-forming element I3 is merelyv representative, and indeed this is true of the entire -size-reducing apparatus, as a very wide variety of mill structures could be employed within the spirit and scope of my invention. Herein the chamber-providing element I3 comprises a depending portion- 25 providing a passage 23 through which material may be introduced to' the size-reducing chamber proper 21. formed 'in the lower part of the member I3. The size-reducing chamber 21 is provided with an arcuate bottom 28, and herein with approximately semicylindrical opposite end portions 29 and 33; and

the chamber is formed with suitable discharge openings, herein shown as arranged in the bottom wall 23 and designated 3| and obviouslyv adapted to be formed in anysuitable wall of the member I3. At the upper end of the supporting and feed passage forming-portion 25, and above the pivot axis of the stub shaft I4 and drive shaft I6, is an upwardly expanding materialreceiving device 32 adapted to receive material -fed through a suitable feed element 33 supported upon a top cover 34, andto deliver it, irrespective of the oscillation of the member I3, at all times l charge and a reversely moving end Vof the chamber, when both are at maximum velocity, will be possible. Accordingly, the size-reducing action lmay involve little or n'o impact, slight impact,

moderate impact, considerable impact and very great impact, depending upon the velocity ofthe chamber, the load it contains, and its amplitude of movement. Accordingly, by appropriately -varying the velocity and amplitude of movement into the connection 25. Preferably. although not necessarily, there is arranged within the sizereducing chamber 21, a portion of size-reducing media 35 w ich may be graduated in size, as illustrated in Fig. 4, to good advantage.

It will be appreciated that, upon rocking of the member I3 through an appropriate arc, material fed into said chamber, and the 'intermingled charge of size-reducing media 35 within the chamber 21, will constitute a load which will be reciprocated within the chamber, the load moving ineach complete cycle of oscillation'of the chamber element I3, twice with the chamberV element and twice relative to the chamber element. For example, to describe briefly a part of a cycle, and beginning with the chamber element I3 in a laterally swung position and with the load in contact with the higher end of the chamber at that time, the chamber will rock downward through its mid-position and over to its opposite extreme position accelerating perhaps during early portions of its movement and deceleratlng through the latter `portion of such movement. The load within the chamber will accelerate with the chamber, and, as it will not be positively decelerated, as will the chamber, through the latters power-oscillating connections, which will shortly be described, the load will continue to move in the same direction with relatively undiminished velocity during the period of deceleration of the chamber though of course friction on the chamber walls does exert a decelerating effect. By appropriately controlling the quantity of material within the chamber, any result between an overtaking by the charge of the end of the chamber, which is ahead of it, as the chamber comes to rest, and an impact between the of the chamberl the contents of the chamber may be subjected to a more or less violent size-reducing action, and, in the event of a tendency of the chamber to fill up, dueto an unduly rapid feed, or any other cause, the rate of material reduction and discharge can be accelerated, ifl suitable means to do this be provided,and thereby overcome the choking tendency mentioned.

Now to take care of the desired acceleration or kdeceleration ofthe size reducing rate, various means maybe provided which will utilize the essence of my invention and control thel sizereducing rate in accordance with the load which the mill imposes upon its driving motor, such being one of the simplest modes of regulation falling within the scope of my invention.

'I'he method of controlling the rate of size reduction for a substantially constant speed drive of the primary drive pulley 2, illustrated in Figs. 3, 4 and 5, comprises broadly means for altering the.. angular range of oscillation of the rocker arm I3, operating on a principle of varying the fulcrum point in an oscillating lever. It will be obvious that shaft 3 is provided with a crank disc 43 having a crank pin 4I projecting therefrom and connected by a connecting rod 42 with a pin 43 mounted between arms 44 and 45 of a substantially upright oscillating rocking arm or lever 43. lThe lower end of the lever 46 is forked, and, between its arms 43, supports a pin 43 and surrounding sleeve 53, said sleeve 5II secured, 'at its ends, in bores 5I formed in-the arms 43, being surrounded by upstanding brackets l52 carried upon a sliding shoe or crosshead 53, and, midway between its ends, supporting one end `oif connect ing rod 54 whose -other end is operatively connected with the pin 23 mounted at the lower end of the arm I3. It will be evident that, with no more structure present than' has so far been described, rotation of the shaft 3 would merely rock the upper end of the lever 46 about the sleeve 53 and there would be no longitudinal movement of the slide 53 nor transmission of motion to the rocker arm I3. To provide for the 1 transmission of motion, bythe lever 43, to the rocker arm I3, an adjustable pivot or fulcrum mechanism is arranged tocooperate with the lever 45 at different points between the ends of the latter. From the opposite sides of the lever 46 project pairs of spaced wings 55, 53; and, between these spaced wings, sliding blocks 51, cooperating with spherical heads 53 on pivotally mounted arms 53, are arranged for upward and downward pivotal movement, movement of the spherical heads 53 moving the blocks 51 up and down between the spaced wings 55, 53 and, accordingly, varying the fulcrum point about which the arm 43 oscillates, since movement of the spherical heads 53 at right angles to the planes in which they are swingably movable is prevented by securing the arm mountings 53 on shafts 3| journaled for oscillation, but fixed against longitudinal movements in bearings 32 carried by the frame-3. Means for simultaneously rotating the shafts 3| at a slow rate is provided, and herein the shafts 5I each support, adjacent one end thereof, a worm wheel 65, and a crossshaft 69 carries worms 91, 61 whichmesh with the worm wheels 65. Rotation of the .shaft 96 through the worms 61 rotates the worm wheels 95, and thereby causes upward ordownward swinging of the fulcrum devices 51, 58 between the plate portions 66, 66. The worm and worm wheel associated with each shaft 6| are so made that the shafts 9| will turn at the same angular rates, and the arms 59 are so arrangedon the shaft A9| that. in all positions of adjustment of said arms through rotation oi' the shaft 86, the centers of the spherical heads 59 will, at all times, remain together in-a common horizontal line, the elevation of such line of course changing as the arms -I Vare adjusted.

` oscillating arm 46 between a position in which the motion transmitted to the rocking arm |9 may be zero (as is the case when the centers of the heads 58 lie in the same horizontal plane with the axes of the sleeve 50) and a maximum (when the spherical heads 58 are in their uppermost position), appropriate means automatically controlled by the load on the driving motor 4 is provided, and the load variation on the driving motor is caused to control the direction and the time of operation of the motor 14. To accomplish this result, various -means may be, of course, employed; and, in Fig. 7, there is diagrammatically illustrated one means suited to this purpose. It will be observed in this gure that the power lines L- and L+ are connectible, through a suitable main line switch 15, with main conductors 16 and 11. A conductor 18 leads from the conductor 16, through a stop switch 19, to a manually operable starting switch 80, from which a conductor 8| leads to the operating coil 82 for a main line contactor 83, and the solenoid 82 is con-- scribed, and a conductor 98 to the line A16. A.

conductor 99 connects the shunt eld 95 to conductor 9|. The main line contactor 83 has associatedwith it a pair of interlocking switch elements, one numbered |00 establishing a hold-ln circuit for the solenoid 82, through a circuitv including conductor 81, conductor 86, fuse 85, conductor 84, solenoid 82, a portion of conductor 8|,

conductor |0|, switch |00, conductor |02, conductor |03, switch 19 and conductor '16. Another switch element |04 moving with the main line contactor 83 establishes a circuit from the con.'- ductor |0|, through a conductor |05, a conductor |06, an operating solenoid |01 and a. conductor |08 to the resistance 92 and thence back through by closing the .manual starting switch 90, and A may be stopped by opening thev manual stop the motor will pass through the coil 91 which is v4arranged in' series with the motor.

. substantially reduced.

servo motor 16. Operation in one direction of conductor 9|, the main line switch, conductors 88 and 81 to the line 11. The solenoid |01 closes 75 an operating circuit including a conductor ||4 amount ofcurrent as the quantity of material 'to speed up the millwill not cause a reduction element |33, conductor |39, conductor |40 and a resistance cut-out contactor H0' and shunts the` rst step of the resistance 92 by way of a conductor l, lthe -switch Ill, conductor ||2 and conductor |09. The contacter IVIII also has moved. with it a further switch'element ||3 which closes connected to the conductor |03, a further con-y ductor H6 and the operating coil H6 of the sec- 0nd resistance cut-out contacter, and a conductor ||1 connected to .the conductor 93. Accordingly, on closure of the switch III, the second resistance cut-out contacter ||9 is closed by the solenoid H6, and the motor is then on the line `with the resistance 92 completely cut out. From the description so far given, it will be evident that the main driving motor of the mill may be started switch 19. The motor will operate as long as current is supplied to it,l and the current taken by- The motor 14 is a reversible. motor andmay be run in either direction or remain idle, depending upon the amount of currenttaken bythe motor 4. The motor 4 will take an increased within the chamber 21 builds up-above a median` value, and will take a smaller amount of current as. the quantity within the chamber 21 is reduced. This fact is made use of to control the direction of rotation of the motor 14, and thereby the direction of adjustment of the fulcrum' elements 51, .and so the intensity of the size-reducing action of the mill |0, when more current is taken by the motor 4, will be increased, and it may be noted that this very thing in itself will cause a further increase in the amount of current drawn by the motor 4. In other words, the adjustment in the quantity of motor current until after the quantity of material in the chamber has been The solenoid or series coil 91 is equipped with a plunger. |20 whose position controls the position of a switch |2|. Contacts '|22 and |23 are arranged at opposite sides of the switch |2| and, when the motor current increases, switch |2| contacts the stationary switch element |22, while when the motor current decreases, a springk |24 causes contact between arm 2| and stationary contact |23'. In its opposite positions the arm |2| causes operation in opposite directions of the the servo motor 14, the direction to cause an increase in the intensity of the milling operation, may first be described. It willV be noted that a conductor |26 leads from the line 16 through arrelay device, Relay, whose function it is to cause only intermittent current transmission therethrough, and whose mode of operation will be further explained hereinafter, through a conductor |21 to the switch arm |2|, through the stationary contact |22, a conductor |28,'a switch operating coil |29, a conductor |30 and further conductors |3| and |44 back to the line 11. The operating coil |29, upon energization,I closes a pair ofswitch elements |32 and |33-and estab- Y lishes then a circuit as follows: from the line 16 tl'iirough the eld |34 Vof the motor 14 through a ccinductor |35, switch |32, a conductor |36, armatuire |31 of the motor 1.4, a conductor |38, switch conductor |3| back to the line 11. Motor 14Wil1 then operatethe adjustable fulcrum devices to increase the oscillation of' arm I3, raising the pivot blocks 51, 51. If, due "to the reduction of current taken in the motor 4, the arm |2| moves into contact with stationary contact |23, an operating solenoid- |42 for the other of the two reverse switches is .energized through the conduct'or |25, the Relay, conductor |21, arm |2|,v

Now one more word about the relay Relay, and

the mode of operation of this form of the invention may be briefly summarized. This relay is of well known commercial construction'and is operative to permit current flow therethrough, say for iive or any other small number of seconds, and then to interrupt current ow therethrough for a period of, say, twenty seconds. After such period, which is adiustable, a renewed current now takes place. This lrelay is shown in the same -circuit with the switch arm |2| and so causes, even though such energization of series coil 91 may exist as to maintain the switch arm |2| in contact with the contact |22, for, let us say, a minute, only very brief periods of operation of the motor 14. As a result, there is prevented the harmful phenomenon of a more or less continuous hunting of the motor 4 due to the lag in the rate of the load change within the chamber 21 behind the adjustments which would otherwise be made by the motor A14. Of course, the relay Relay, save for the fact that larger currents would have y be .arranged directly in the operating circuit'of the motor 14. This is not impossible, but merelyl less desirable.

Now the mode of operation of this form of'the invention will be clearly apparent from what.

has been described. Feeding arrangements.as through a belt conveyor, having been made available for the supply chute 33, theoperatorwill close the starting switch 80,' and through; the circuits which have been described, the motor 4 -wi1l be started. This will cause the mill-chamber-forming member VI3 to be rapidly and powerfully oscillated, though with short stroke,'xand the load therein which may initially be only size-reducing media, will -be moved, as soon as some material begins to come'in, in the manner heretofore described. As feed to the chute 33 continues, the load on the motor 4 will build up;

to be controlled thereby, might4 of material within the chamber is being reduced. Should the rate of feed fall ofi, the current taken Aby the motor 4 will be reduced as the chamber tends to empty itself, and the contact arm |2| will then move into contact with the stationary contact |23 and the motor 14 will be reversed and the stroke of the mill chamber shortened with a reduced rate of size reduction and a refilling of the chamber to optimum load conditions. The relay Relay may be omitted if a mill of very rapid size-reducing capacity is being employed, or the time delay between the duration of periods of current supply through the relay may be varied to i'it diiierent mills. If feed is'interrupted, and the quantity of sizereducing media be properly determined, impingement of the chamber ends upon the chamber load may be entirely discontinued automatically.

In Fig. 6 a different arrangement is shown. In this case, instead of varying the amplitude of movement of the .size-reducing chamber, a substantially constant rate and amplitudeof chamber oscillation is maintained, the crank pin 4|' .being directly connected by connecting rod |5 with the pin 20' on rock arm |94. I-n this form circuit connections for controlling the motor 14 may be used, and,` if the chamber tends to get too full, the motor 14' will be operated in Va direction to move the gate |53 to ar-,educe the` area of the feed supply passage, while, should the'chamber load become .too light, opposite movement of the motor will beeifected. The general control of size' reduction to maintain optimum conditions will, however, be present in this device as in the other. i

From the foregoing description, it will be evident that I have provided an improved milling apparatus in which automatic control is provided, whereby optimum size-reducing conditions may be maintained. DifferentA formshave been illustrated in which the grinding rate is increased or diminished while the feed rate is maintained case, the arrangements are simple, positive, reliable and substantially eil'ective to produce the desired results. It is obvious moreover that I and as a result, the original short stroke of the mill will be increased as soon as the quantityY of material in the chamber 21 gets more than isidesirable, as this will cause the motor 4 to draw more current -and so move the switch arm V|2| into contact with the stationary contact rU22.

This will, as above explained, cause the motor 14 to operate in a direction to move the fulcrum fielements 58 upwardlyv and increase the range of oscillation ofthe arm I5, andso the chamber 21 will increase the rate of .size reduction in; the chamber, and excessive increase will be avcllided by reason of the fact that the adjustmentg will not be carried on continuously by the apparatus illustrated throughout the time that the qualntity have provided an improved method of milling, in which the rate of size reduction is varied in proportion to the load on the driving motor.

IWhile I have in this application speciiically described two forms which the invention may assume in practice, it will be understood that these forms are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In combination, a milling chamber, means for effecting movement of said milling chamber increase in the quantity of material therein to eect a milling operation therein, said milling chamber having means for supplying material thereto and means for discharging milled material therefrom as a substantially continuous process during operation, and means including means for altering the movement of said chamber for regulating the intensity of the milling operation in said chamber automatically in direct accordance with the therein.

3. In combination, a milling chamber, means for eecting movement of said milling chamber to eilect a milling operation therein, said milling chamber having means for supplying mate rial thereto and means for discharging milled material therefrom as a substantially continuous process during operation, and means for automatically increasing chamber movement upon increase in the quantity of material therein and decreasing the chamber movement upon decrease in quantity of material therein to eect a resto- -ration of the materialload in said chamber to a predetermined quantity upon deviation therefrom, said automatic means including means for quantity. upon deviation quantity of material process during operation, and m'eans'for regulating the intensity of the vmilling operation in said chamber automatically in accordance with the quantity of material therein'including a variable lever mechanism for transmitting diierent ranges of movement to said milling chamber. 8. In combination, a milling chamber, a moi tor for eilecting movement of said milling chamber to `eiiect a milling operation therein, said milling chamber having means for supplying material thereto and means for discharging milled ranges of movementto said milling chamber and ia motor for adjusting said lever mechanism whose operation is regulated by the power input to said 'first mentioned motor.

9. In combination, a milling chamber, a motor for effecting movement of said milling chamber to effect a milling operation therein, chamber having means for supplying material thereto and means for discharging rial therefrom as a substantially continuous varying the linear speed of chamber movement.

4. In combination, a milling chamber, means for eiecting translatory movement of said milling chamber to eife'ct a milling operation there-l in, said milling chamber having means for supplying material thereto and means for discharging milled material therefrom as a substantially continuous process during operation, and means for regulating the intensity of the milling operation in said chamber automatically in direct accordance with the quantity of material therein includingmeans for varying the travel of the chamber. f

process 'during operation, and means for regulating the intensity of the milling operation in said chamber .automatically in accordance with the quantity of material therein including a variable lever mechanism for transmitting different ranges of movement to said milling chamber and a motor for adjusting said lever mechanislnwhose direction of operation is controlled by the power input to said iirst mentioned motor.

10. In combination, a size-reducing mill comprising a movable milling chamber, a drivingmof tor therefor, driving connections between said 5. In combination, a milling chamber, means for eecting reciprocating movementfof said milling chamber to eect a milling operation therein, said milling chamber having means for supplying material thereto and means for clischarging milled material therefrom as a substantially continuous process during operation, and means for regulating the intensity of the milling operation in said chamber automatically in direct accordance with the quantity'of material therein including means for varying the range of reciprocation of said chamber.

6. I n combination, a milling chamber, means for eiecting oscillatory movement of said milling chamber to eilect a milling operation therein, said milling chamber having means for supplying material thereto and means for discharging milled material therefrom as a substantially continuous process'duringoperation, and means for regulating the intensity of the milling operation in said chamber automatically in direct accordance `with .the quantity of material therein including means for varying the range of oscillation of said chamber.

'1. In combination, a milling chamber, means speed of actuation of said mill, and

motor and said milling chamber including millspeed varying mechanism, and means governed by the load in said mill for automatically acljusting said speed varying mechanism to increase the speed of the chamber with increased load.

l1. In combination, a size-reducing mill, a

driving motor therefor, driving connections between said motor and said mill including millspeed varyingmechanism including adjustablefulcrum lever means through which the. drive is transmitted to said mill, and means governed by the load in said mill for adjusting said speed varying connections by varying the lever fulcrum.

l2. In combination, a material-size-reducing mill, a driving motor therefor, driving connectionsbetween said motor and said mill including adjustable connections for varying the speed of actuation of said mill and means including a servo-motor governed by the load in said mill for adjusting said speed varying connections.

13. In combination, a material-size-reducing mill, an electric driving motor therefor, driving connections between saidmotor and said mill including adjustable connections for varying the speed oi actuation of said mill, and means includingan electric servo-motor governed by the load on said driving motor for adjusting said speed varying connections.

14. .In combination, a materialsizereducing mill, an electric drivinggmotor therefor, driving connections between said motor and said mill including adjustable connections for varying the means governe'd by the load in said mill for adjusting said speed varying connections including a servo-momilling operation in said in accordance with the l said milling milled matecontrolling means governed by a series relay in said driving motor circuit.

15. The method oi controlling the output or an oscillating mill automatically which comprises automatically varying the range oi' oscillation of said mill directly with the quantity o! 4material fed lthereto to increase such range with the rate of feed.

16. The method of precluding the choking of the movable size-reducing chamber of a continuously operating mill which comprises varying the linear rate of movement of such chamber automatically directly in accordance with variations in the quantity o! material in said chamber.

17. The method of precluding the choking of an oscillating mill which comprises varying the amplitude of oscillation of said mill in step and in direct accordance with variations in quantity of material in said mill.

18. 'I'he method of precluding the choking of an oscillating mill which comprises varying the amplitude oioscillation oi said mill in step and in direct accordance with variations in quantity' of material in said mill while maintaining the time rate o! oscillation substantially constant.

*tor for adjusting said connections and having 19. In combination, a material-size-reducing mill having a size-reducing chamber and provision for the supply to and discharge from said chamber o! material during chamber movement, and having means including a motor for driving said mill at a substantially uniform rate, and automatic means governed by the mass of the material in said chamber for varying the ampli- -tude`of milling movement responsive to and in direct accordance with variations in the load in said chamber. l

20. In combination, a -material-size-reducing mill h'aving an oscillatory size-reducing chamber and provision for the supply to and discharge from saidchamber o! material during chamber movement, and having means including a motor for driving said' mill to effect chamber oscillation at a substantially uniform rate, and automatic means for varying the milling rate responsive to variations in the load in said chamber including means the adjustment or whose position controls the ratio between material supply and discharge rates ano 'means governed by the power required by said motor for adjusting said last 25 named means.l

CHARLES F. OSGOOD.

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