|Publication number||US2613036 A|
|Publication date||Oct 7, 1952|
|Filing date||Jan 11, 1947|
|Priority date||Jan 11, 1947|
|Publication number||US 2613036 A, US 2613036A, US-A-2613036, US2613036 A, US2613036A|
|Inventors||Robinson Richard S|
|Original Assignee||Vibro Dynamic Engineering Inc|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (10), Referenced by (16), Classifications (6)|
|External Links: USPTO, USPTO Assignment, Espacenet|
R. S. ROBINSON VIBRATORY AND ROTARY BALL. MILL Oct. 7, 1952 Filed Jan. 11, 1947 5 Sheets-Sheet 1 VP T T 5 T WM G 5 m% H m RV! M 3 t rw.%0r MW ad 3 h E R 1 w. m m r m n ma R S ROBINSON VIBRATORY AND ROTARY BALL MILL Fla. 3
Oct. 7, 1952 Filed Jan. 11, 1947 Oct. 7, 1952- R. s. ROBINSON VIBRATORY AND ROTARY BALL MILL 5 SheetsSheet 3 Filed Jan. 11, 1947 INVENTUR R/UMRD s. fioa/lvso/v 5% at 7% Oct. 7, 1952 R. s. ROBINSON ,613,
VIBRATORY AND ROTARY BALL MILL Filed Jan. 11, 1947 5 Sheets-Sheet 4 o/scm aE IN VEN TOR P/CHA r20 5. ROBINSON BY g Y TORNEV 0m. Ti} 1952 R. s. RomNsoN 115 3 vzsmi'omr mm ROTARY BALL Mm.
Filed Jan. 11, 194'? 5 skews-sheet 5 j l I I l 1 I I I mMs/vra/F 6017 90 5 008/400 It has been found Patented Oct. 7, 1952 VIBRATORY AND ROTARY BALL MILL Richard S. Robinson, Gloucester, Mass, assignor, by mesne assignments, to Vibro Dynamic Engineering, Inc., Boston, Mass, a corporation of Massachusetts Application January 11, 1947, Serial No. 721,507
This invention relates to comminuting, or .pulverizing machines, and moreparticularly to ball orrrod mills for grinding solid materials into small particles.
In mills used for grinding materials, the speed with which the desired particle size may be obtained is largely dependent on the characteristics of the material being ground, but fora givenmaterial, mill, and ball size, there exists a critical speed ofrotation for the maximumrate of grinding. If this speed of rotation is exceeded the balls and material tend to rotate with the container and the grinding efiiciency isreduced.
An object of this invention is to increase the grinding efficiency of a ball or rod mill.
Another objectis to raise the critical speed of a ball mill.
A further object is to effiectively disperse the material in a ball mill, thereby preventing agglomeration of the material.
. l Still: another object is to prevent the material being ground from coating the inside of the mill. An additional object is to provide a novelmechanical movement for ball mills. H
,The foregoing and other objects of the invention will be best understood from the following description of someexemplifications thereof,.reference being had to the. accompanying, drawings, wherein:
Fig. 1 is a perspective viewof one, type. of. apparatus embodying the invention;
Fig. 2 is aperspective view of, another typeof apparatus embodying the invention;
Fig. 3 isan end view of the apparatus of Fig-2; Fig. 4 is a schematic view of amodification of Fig.1; l 5 is perspective viewofstillYanother type of apparatus embodying the invention;
Figs. 6 and 7 areside and front views, respectively, of the apparatus of Fig. .5;
Fig; 8 is, a front view partly broken away of another apparatus embodying the invention:
:Figs. 9 and 110 are .side and front .viewsyrespectively, of another apparatus embodyingthe .in-
that if a vibratory-motion is imparted to a ball or rod mill, inaddition to the rotation, an 'increasein grinding efiiciency is obtained, in excess of that anticipatedfrom the greater energy input. This [is'particularly true ifthe'millis made part of a" resonant system and is operatedat resonance; since the amount of provide four horizontal guideways.
2 power required to maintain the vibrations is a minimum at resonance.
In regard to the comminuting or pulverizing action itself, a vibration along the horizontal axis of rotation not only produces a greater grinding action of itself, but by dispersing the material increases the rotary grinding action and even raises the critical speed, as defined above.
A vertical vibration normal to the axis of rotation provides anadded impact of the balls against the material, and also tends to disperse the material.
Such dispersion of the material is particularly advantageous in. dry milling or comminuting Where agglomeration issometimes severe. Also, the vibration tends to prevent the material being ground from coating the inside of the container. It is, therefore, the purpose of this invention to provide, in a pulverizing machine, vibratory or translatory motion simultaneously with the rotary motion. In the following specification and claims, the phrase rotary motion" is used to refer to torsional or turning movements of less than 360, in either direction, or in successive opposite directions in an oscillatory manner, as well as to repetitive 360 rotations in the same direction.
Now referring to the drawings, with particular reference to Fig. l, a suitable fixed support includes a pair of spaced upright members I as shown. A bearing 2is provided near the upper end of each of the upright members, these bearings being horizontally positioned and aligned. J ournaled for. rotation in bearings 2, about a horizontal axis, by means of a pair of stub shafts 3 fixed. at opposite ends thereof, is an external framework 4 which may be four-sided and cagelike as shown. Each of the four horizontallyextending arms of the frameworkA has an elongated horizontal recess 5 cut therein, to thereby Supported in these 'guideways for sliding or vibratory movement with respect to framework 4 and'for rotary movement with framework 4, is a second cagelike' frame 6, which is also four-sided. A helical or coiled spring I, is horizontally positioned between framework 4 and one end of framefi, by meansof suitable .abutments which extend into opposite ends of said spring, for a purpose-which will be pointed outbelow; one end of this spring bears against framework 4 and the opposite end against frame 6. v
The inner frame 6 is adapted to removablyreceive and support therein a container 8, said container being firmly mounted in this inner frame to follow themovements thereof. In container 8, which may be a porcelain jar of the type used in the conventional jar mill, are placed the material to be comminuted or pulverized and the relatively hard balls or rods. A thrust ball bearing 9 is fixed to the end of inner frame 6 opposite from spring I, this bearing being coaxial With spring I, shafts 3, and bearings 2. The outer raceway of bearing 9 is rigidly attached to frame 6. Attached to the inner raceway of bearing 9 is a horizontally-extending oscillatory shaft II), this shaft being coaxial with stub shafts 3 and extending freely through one of said shafts 3 to a point external to the spaced upright support members, the corresponding shaft 3 being hollow for this purpose. Shafts I and 3 are free to rotate with respect to each other.
Stub shafts 3 and outer framework 4 (and thereby also inner frame 6 and container 8) are continuously rotated about a horizontal axis by any suitable means. For example, a pulley II may be rigidly attached to one of the shafts 3, this pulley being rotated in the direction indicated by the arrow by means of a belt I2 from a pulley I3 on the drive shaft of a motor I4. The relative diameters of pulleys I I and I3 are made such that the number of revolutions per minute of container 8 is rather low.
In order to imp-art horizontal motion, or motion parallel to the axis of rotation, to container 8, the outer end of shaft II] is attached eccentrically through a pivoted link I6 to a pulley I5, the axis of which is horizontal but is at right angles to the axis of rotation Of the frameworks, this pulley being driven from motor I4 at a suitable angular velocity by means of worm-and-worm-wheel arrangement I'I, through subsidiary pulley I8 and belt I9.
- It is desirable, for different grinding actions or for grinding diiferent materials, to be able to arrangedradially of said pulley. By pinning link I6 to pulley I5 at any desired hole 81, it is possible to vary the stroke amplitude or the amplitude of vibration or horizontal motion of the container 8.
In the embodiment of Fig. 1, the container 8 is rotated about an axis passing therethrough, due
to the rotation of both frameworks 4 and 6 about a horizontal axis by pulley II. Since the inner framework 6 is capable of sliding movement on the surfaces or guideways 5 in a direction parallel to the axis of rotation, and since link I6 is reciprocated in the direction of the arrows by pulley I5, it will be seen that vibratory motion parallel to the axis of rotation, in the direction of the arrows, will be imparted to the container 8 simultaneously with the rotary motion thereof.
The mass of the vibrating system including the inner framework 6, the container Ii with its charge, the shaft I0 and the link I6, together with the stiffness of the spring 1, predetermine a resonant vibratory frequency for said system if the mass of frame 4 and its supports is large compared to that of jar 3 and frame 6. The mass of the material being ground in any'ball mill is .usually small compared to the mass of the balls,
of the jar 8 and vibrating frame 6 is sufiiciently small to consider the external frame 4 rigid. Here, then, we have a vibratory system, which has a predetermined resonant vibratory frequency, resiliently attached to a rigid support.
It has been found that, when such a vibratory system is vibrated at a frequency which is equal to its natural resonant vibratory frequency, the
- amount of power which must be expended to maintain the vibration is a minimum. In fact, the only input energy required is that necessary to overcome frictional losses and to supply the losses of the spring. By proper design, these can both be made extremely small. The losses are almost entirely in friction in the guides, there being almost no loss in the spring itself.
In this invention, the gear ratio at I! and the ratio of diameters of pulleys I5 and I8 are made such that, in connection with the speed of rotation of motor It, the vibratory system will be vibrated at its natural resonant vibratory frequency.
Now referring to Figs. 2 and 3, these figures show a means of vibrating a jar mill in a direction normal to the axis of rotation. In this case the fixed support I includes a pair of spaced upright members similar to those of Fig. 1. However, here the bearings 2 for the shafts 3 of the rotating frame 26 are mounted in opposite support members 2| which are slidably mounted in vertical guideways 22 provided in the upright members of support I, so that said bearings are free to slide in a vertical direction. A coiled or helical spring 23 is positioned between each of the support members 2I and a corresponding abutment on the fixed support I, in order to resiliently support the vertically movable parts. By means of these springs, the vertically-vibratile system is resiliently mounted in the fixedframework or rigid support I.
The jar 8 is firmly but removably mounted in frame 20, so that it follows or partakes of the movements of said frame; as a result of the operationof the driving means to be described below,;jar 8 with its charge has rotary motion imparted to it simultaneously with vertical vibratory motion.
The members 2| are attached to opposite ends of a horizontally-extending yoke 24 which in turn is attached to a means for vibrating the yoke in simple harmonic motion. This latter means comprises a disk 25 which is rotated by the drive shaft of motor I4, a pivoted link or arm 26 being fixed eccentrically to disk 25 at one end and to a downwardly-extending portion of yoke 24 at its oppositeend. Thus, when disk 25 rotates, the yoke 24, members 2I, frame 20.v and jar 8 are reciprocated vertically. The eccentricity of link 26 with respect to disk 25 is made capable of being adjusted, as in the mbodiment of Fig. I, in order to vary the amplitude of the stroke or of the vertical reciprocation of frame 20. This adjustability feature is not shown, in order not to unduly complicate the drawing.
Frame 20 and jar 8 are also rotated about a horizontal axis simultaneously with this vertical vibration. A shaft 3, which extends through the bearing 2 in member 2 I, has fastened to the end thereof a pulley 21. A pulley 28, fastened to and driven by the output shaft of motor I4, drives pulley 2! by means of a belt 29, thus impartingrotary motion to the frame 20, jar 8 and its contents, about a horizontal axis through said jar, said axis being provided by shafts 3 and bearings 2. In order to allow for vertical motion of shaft Band thereby also pulley 21 during r0- and the containers.
tation thereof, a resilient belt-tightening pulley 30, which is pivotally mounted on a fixed support, may be used on belt 29. Pulley 30 is spring-biased or weight-biased to maintain belt vibratory system and the stiffness of springs 23 determine the natural resonant vibratory frequencyof said system if the mass of support is largecompared to that of parts 8, 20, and 2 I, and the oscillatory driving means 25, 26, etc. 'is'designed to vibrate said system at a frequency equal to said resonant frequency. Therefore, the power needed to maintain the vibratory system in vibration is a minimum, while at thesame time the grinding or pulverizing advantages of vibration along with rotary motion are obtained. Nowwith reference to Fig. 4, this figure shows a system somewhat similar to Fig. l, but utilizing a resonant vibratory system with two jars. The supporting frame I has been omitted from the drawing. The outer framework 4 is like that of Fig. 1 except that it is somewhat longer and has longer slots or guideways-3 therein. Mounted in these guideways for vibratory or sliding movement with respect to the outer framework, are a pair of spaced inner frames 3| and 32 which are substantially similar to each other and to the inner frame 6 of Fig. 1.
,Firmly mounted in each of these frames is a jar or container .8 in which is placed the material to be comminuted or pulverized, these jars being mounted removably yet tightly in their respective frames so as to follow the respective tends through the stub shaft 3 to the exterior:
of the machine.
, Shaft I0 is adapted to be horizontally reciprocated, through an adjustable clutch mechanism 88 to be described hereinafter, by a driving shaft 89, which is horizontally reciprocated, oscillated, or vibrated by means of an eccentric and link arrangement. as in Fig- 1. As in Fig. 1, the
"eccentricity of the link is made capable of adjustment with respect to the rotating, drive pulley, in order to vary the amplitude of horizontal vibration of the inner frames 3| 1 and 32 Frame 32 is coupled to frame 3|, and thereby alsoto the vibratory driving means, only by means of a helical spring 33 the opposite ends of which contact, respectively, the adjacent ends of frames 3| and 32 and which forcefully surrounds and engages, near each end of said spring, provjecting bosses integral with the adjacent ends of the respective frames; spring 33 engages frame 3| at theend thereof opposite from bearing 9. The natural resonant vibratory frequency of a vibratile system comprising. two,,bodies con- 'nected together by a spring is r dissimilar inmagnitude. It is only necessary that the momenta. (mass times velocity) on both sides of the nodal point be equal.
If the masses are equal to eachother, of course, the nodal point will be at the midpoint ofthe length of the The vibrating system of Fig. 4 is meantto be a resonant system, with the frame 32 and'its jar acting as a compensating mass for the frame 3| and'its jar. Each of thevibrating frames has amass, which masses, together with the stiffness of the spring 33, determine the natural resonant vibratory frequency of the vibratile systemasa whole, and the vibratory driving means 1,88, etc. is arranged to oscillate or vibrate the frame 3| at this frequency. Where less than a fullload charge is to be treated 'in the mill, the resonant frequency as defined in Equation 1 may vary, since the masses m1 and me will then have values different from their original ones. Since the driving motor has a substantially fixed speed, it may no longer be vibrating the masses .at'the resonant frequency of the system, which is an optimum condition. In this event, separate ex.- ternal masses may be addedto both sides of the system to bring the resonant frequency of the system back to the proper value. One such ex,-
ternal mass is shown at 34, in the form of an adjustable counterbalancing means attached to the end of frame 32' opposite from spring 33; asimilar mass. (not shown) may be attached to frame 3|. Such amass could also be utilized on one side of the system when only a singlejar is used in the system, to make up for the mass of the missing jar, or whenever, for any reason, there is inadequate mass on either side of th system.
It will be seen that the frames 31 and 32 constitute two vibratile masses connected by the spring 33, frame 3| being adapted to. be positively vibrated by the external vibrating means. When two masses are connected by a spring andone of the masses is set into vibration by an external means, it iswell-known that the other masswill beset into vibration also by forces transmitted through the spring. Therefore, in the Fig. 4 embodiment, frame 32 will be vibrated by such forces, and,.since the frames 3| and 32 are meant to be vibrated at their naturalresonant vibratory frequencies, the vibrations of frame 32 will be always out of phase with those of frame 31 (that is, when frame 3| moves to the left, frame 32 moves to the right, and vice versa).
In Fig. 4, the only power necessary to maintain the frames in vibration, at resonance, is-that necessary to supply the elastic losses in the spring 33 and frictional losses, which losses can be made very small. -As before, the power losses at the spring itself are very small, and most of the total loss is in the form of friction in the guides. It has been found, however, that substantially greater power is required to bring the vibrating system up to speed and the proper mode of vibration, from astandstill; On a small scale model,
which the embodiments of Figs. land 2 are intended to be, it is possible to throw the driving motor on the line, thereby bringing the vibrating system up to speed and the proper mode-of vibrasynchronous 1 .An adjustable or variable clutch mechanism 88 is connected between driven shaft I and driving shaft 89. Mechanism 88 may be, for example, of the type described in Smith Patent 2,303,407, dated December 1, 1942, which is a mechanism for coupling a vibratory driving means to a vibratory system after the driving means has reached resonant speed. By operationof handwheel 88a, the vibrational amplitude transmitted from the source 89 to the vibratory system H), etc. may be varied. In the procedure known as synchronous starting, thehandwheel 88a is adjusted to the position corresponding to zero vibrational amplitude of the driven system I0, etc. Then the driving motor (not shown in Fig. 4) is thrown on the line and allowed to come .up to-resonant speed, thus rotating the outer framework 4. When the motor has reached resonantspeed, handwheel 88a is operated to gradually increase the vibrational amplitude, of shaft and the resonant vibratory system, from zero.
Inthis way, the vibratory system is started into vibration at its resonant frequency; the'driving motor does not have to pick up speed before reaching resonance, so that the load thereon reinainssmall and a small motor may be utilized. Alternatively, the clutch mechanism may be a similar arrangement whereby the vibratory stroke can be varied while the drive motor is running.
In the two-vibrating-bodies machine of Fig. 4, there will be less vibration of the external fixed .support means than in Fig. 1, due to the presence of the second vibrating system or compensating mass 32 Whichtends to exert a force on the support which is equal and opposite to that exerted by the system 3|.
The pulverizing advantages of vibration of the mill along or parallel to the axis of rotation thereof are obtained with the Fig. 4 machine, as well as with the Fig. 1 machine, but in Fig. 4 twice as much material can be comminuted or pulverized as in Fig. 1, because there are two jars.
The machine of Fig. 4 could be coupled with the system of Fig. 2 togive both horizontal and vertical vibration, similarly to the combining of the apparatus of Fig. 1 with that of Fig. 2 to provide both vertical and horizontal vibration simultaneously with rotation, said combining being set out more fully hereinafter.
Now with reference to Figs. 5-7, this system illustrates a mill in which rotary motion is imparted to the mill back-and-forth through an angle of less than 360, in the manner of torsional vibration, simultaneously with vertical vibration of the mill. As in Fig. 2, an outer frame 35 is journaled for rotary movement in bearings 2 which are mounted in opposite support members 2| which are slidably mounted in vertical guideways 22 provided in the upright members of fixed support By means of springs 23, the vertically-vibratile system is resiliently mounted in the fixed framework or rigid support The yoke 24 and means I4, 25, 26, etc. for vibrating the yoke 24 and frame 35 vertically are the same as described above in connection with Fig. 2. The
tioned in frame 35 by firmly engaging an inner frame 44, frame 44 being journaled for free rotation with respect to frame 35, by means of pins 31 which are fixedly attached ,to opposite ends of the inner frame 44 and which are journaled in stub shafts 3 which are integral with frame 35. Frame 44 is sufficiently smaller in area than is frame 35, to provide proper clearances for unimpeded movement of the inner frame relativeto the outer frame. Frame 44 is coupled toframe 35 mechanically by means of a helical spring 38 the opposite ends of which contact, respectively, one end of frame 44 and the adjacent end of frame 35, and which forcefully surrounds and engages, near each end of said spring, projecting bosses integral with said one end of frame 44 and said adjacent end of frame 35. The inner frame 44 is oscillated rotatively by the torsion applied through the spring 38 that is rigidly connected at its ends to the two frames 35 and 44.
There is a stub shaft similar to shaft 3 at the end of frame 35 adjacent spring 38, and this shaft extends outwardly beyond the space between the fixed upright members; at thegend of this shaft there is attached an adjustable counterbalancing means 39 similar to that of Fig.4.
Stub shaft 3 at the end of frame 35 opposite spring 38 also extends outwardly beyond the space between the fixed upright members, and at its outer end has fixed thereto a radiallyextending plate 40. One end of a link or arm 4| is pivotally attached to the outer end of plate 40 (therefore, link 4| is eccentric with respect to shaft 3). A rigid bracket or support-42 is fixedly attached to the outer surface of the support member 2| which is remote from spring 38. Said bracket extending outwardly and downwardlyfrom member 2| and carryingv a bearing at its lower end in which is journaled for rotation a pulley 43. r
The end of link 4| opposite from plate 40 is pivotally attached to pulley 43 eccentrically thereof; the eccentricity of link 4| with respect to shaft 3 is substantially greater than the eccentricity of said link with respectto pulley 43, so that continuous complete rotation of pulley, 43 produces rotary motion of shaft 3 and frame 35 in an oscillatory, back-and-forth manner through an angle of less than 360, which might be termed torsional vibration.
Pulley 43 is continuously rotated, by means of a belt 29, from a drive pulley 28 on the shaft of motor M. In order to allow for vertical movement of yoke 24, members 2|, frame 35,'frame 44, trough 3B, and the consequent vertical movement of pulley 43, by the vertical driving means I4, 25, 26, etc. aforesaid, while enabling torsional vibration or rotary motion of frame 35 to be simultaneously eifectuated, a resilient belttightening pulley 30 is used on belt 29, "similarly to Fig. 2.
By the operation of the above-described driving means, vertical motion (or vibratory motion normal to the axis of rotation) of frame 35 (and therefore also of frame 44 and trough 36, because of pins 31) is eifectuated, simultaneously with rotary motion, or torsional vibration, of frame 35, about an axis through trough or container 36.
It will be noted that the external frame 35 plus whatever counterbalance 39 is necessary provides the resonant compensating mass for the mill. The rotary motion or torsional vibration is applied to this compensating mass and is transmitted, through torsional spring 38, to'the inner frame 44 and trough 36, to cause said'inner frame and trough to execute torsional vibrations along with its vertical movements, these torsional vibrations being in effect 180' out of phase with those of external frame 35. In this way,
the grinding or pulverizing advantages due to vibration of the mill simultaneously with rotary motion thereof are achieved;
It will be noted that two resonant vibratory systems are provided, one being the vertical system including springs 23 and the other being the torsional system including spring .38. The masses of each of these systems, together with the stiifnesses of the respective springs, predetermine a natural resonant vibratory frequency for each system. The respective driving or vibrating means are designed to vibrate each of these systems at a frequency equal to its resonant vibratory frequency, the amplitude of the torsional vibration being substantially larger than the amplitude of the vertical vibration. Thus, the power required to maintain each of these systems in vibration is aminimum. I l
The modification shown in this figure is intended to be a small mill, so that a variable clutch mechanism for the vibratory system need not be used; motor 14 is thrown'directly on the line to bring the vibrating "system up to speed and the proper mode of vibration. synchro nous starting need not be utilized on this machine. M v
Due to the fact that the rotary motion of this mill is through an angle of less than 360", the container 36 can be a trough, since a cover is not necessary. Also, the mill could be made continuous with either balls or rods. desired, another container and balls could be used in this machine, making the apparatus analogous to that of Fig. 4. Such a modification could be made in a manner obvious to those skilled in the art.
Fig. 8 illustrates a an apparatus in which a resonant mass is utilized in connection with a horizontally-vibrating continuous ball or rod mill. A cylindrical container 45, which may be made of metal such as steel for example, is jourw naled for rotation about a horizontal axis passing through said container, by means of a pair ofhollow shafts 49, in and between a pair of fixed bearings 46 which are mounted near the respective upper ends of two spaced fixed upright members 55. The outer raceway of each of these bearings 45. is mounted with some degree of looseness in its respective upright member, while rotation of said raceway with respect to saidmember is prevented by any suitable means, such as a key-and-keyway arrangement for eX- ample. Therefore, the container 45, together with its bearings 46, is free tomove'horizontally with respect to the fixed supports 55, in addition to its being free to rotate about a horizontal axis. Container 45 is rotated continuously about a horizontal axis by means of: motor 24, a driving gear 4! on the drive shaft of which engages a horizontally oscillated, vibrated or reciprocated,
through adjustable clutch mechanism 88, by a driving means which may comprise a. pulley 53 having aim or arm 54 pinned eccentrically saids rin s. p g
thereto and which in turn is pivotally connected to the, drive shaft 52' of the clutch mechanism 88.. As in Fig. 1, the eccentricity of the link54 is made capable of adjustment with respect to the pulley 53, in order to vary the amplitude of horizontal vibration of container 45.
Pulley 53 is adapted to be continuously rotated by any suitable driving means (not shown, but which may conveniently be motor l4), to thereby cause horizontal vibration or reciprocation of shaft 52', shaft 52. (when handwheel 88a is properly adjusted) plate 156, bearing 5|, yoke 50, shafts 49, bearings 46, container 45, and! gear 48, simultaneously with the rotation of container 45, shafts49, and yoke structure 50. In order to put the vibrating system into operation from a stand, still, synchronous starting is used for the vibrating movements of the container, the hand wheel 88a being operated. accordingly. This synchronous starting procedure has been explained indetail above, in connection with Fig. 4, and briefly consists in bringing the driving motor up to a speed corresponding to resonance of the vibrating system before providing any amplitude of vibration, and then gradually increasing the amplitude of vibration from zero to the desired value, this being possible through clutch mechanism 88. i a i A suitable weight or mass 58 is positioned concentrically with shaft 52 and is resiliently mounted, for example by means of a plurality of flat leaf springs 59, on a fixed support 6 0. Mass 58 has an aperturefil extending therethrough, concentric with shaft 52, of sufficient size to allow forfree longitudinal movement of said shaft therein with respect to said mass. Mass 58, for example, may be of the same diameter as plate 55. Due to the above-described mounting, mass 58 is capable of executing horizontal vibrations. A plurality of bosses 51 are fixed to plate 56, having their centers arranged, for example, on the circumference of, a circle concentric with said plate. A plurality of bosses 82 aligned with bosses 51 are fixed to the end surface of mass 58 which is adjacentplate 56. A plurality of coil springs 63 are positioned between plate 56 and. :mass'5B, each of these springs having its axis horizontal and each spring firmly and tightly surrounding, at its opposite ends, a pair of aligned bosses 51,
62. e i l Mass-58 is arranged to act as a resonant or compensating mass for the mass comprising container 45 and its contents. When plate 56 is vibrated, horizontally, by means of shaft 52, at its resonant frequency determined by the mass of the containerand the stifinessof spring 63, mass 53wil1 be set into vibration at the same frequency, but out of phase with the vibrations of said plate, by means of forces transmitted through Due to the provision of a resonant compensating mass, the amplitude of the vibrations transmitted to supports 55 is reduced, while at the same timethe advantages of reduced input power for-"vibrating purposes are obtained. The pulverizingadvantages described in detail above are obtained with this apparatus, since in this mill vibratory motion is imparted to the container 45, containing the balls or rods and-the charge, simultaneously with the rotary motion thereof.
In order to make this mill continuous, shafts 49 at each end of container 45 are hollow, the container itself being provided with internal weirs and screens in the usual way, with balls of different sizes being placedin the separate chambers thus provided. A feed spout 54, which connects with the hole in the left-hand shaft 49, enables the charge of unpulverized material to be fed into container 45. The hole in right-hand shaft 49 connects with the yoke structure 50, which is an open framework, so that the pulverized material discharges through the openings in said yoke into discharge spout or trough 65 placed therebeneath.
Now referring to Figs. 9-10, an apparatus combining that of Fig. 1 with that of Fig. 2 is shown, whereby both vertical and horizontal vibration of the mill is provided, simultaneoush with rotation thereof. These figures show a small mill, analogous to those of Figs. 1 and 2, which is capable of being started by throwing the driving motor on the line to bring the entire vibrating system up to speed and the proper mode of operation; synchronous starting is not necessary with such a mill.
An outer'framework 4, similar to that of Fig. 1, is mounted for rotation about a horizontal axis by means of a pair of shafts 3 and a pair of horizontally-disposed aligned bearings 2 at opposite ends of said framework. Bearings 2 are fixed in corresponding vertically slidable members 2| which are adapted to slide in vertical guideways 22 provided in a pair of upstanding fixed spaced supporting members or standards fastened to a fixed support or base I. Framework 4 is provided with horizontal guideways 5 similar to those of Fig. 1.
Mounted for sliding or reciprocating movement in guideways 5 is an inner frame 6, inside which is firmly fastened a jar or container 8 which contains the balls and the charge. J ar8 partakes of the movements of frame 6. A helical spring I couples one end of frame 6 to framework 4. Frame 6'is mounted sufficiently rigidly in framework 4 to follow the rotary and vertically-reciproca'ting movements of said framework. A bearing 9, similar to that of Fig. 1, is fixed to the end of frame 6 opposite from spring I and permits rotation of frame 6 with respect to shaft I0, while at the'same time coupling frame'fi to shaft III for horizontal vibration or reciprocation. I As in'Fig. 2, a coil spring 23 is positioned between each of the sliding members 2| and a fixed abutment of support I. In order to vibrate members 2I, framework 4, and frame 6 vertically, a yoke 24 is provided, as in Fig. 2, the opposite ends of said yoke being attached to the respective members 2 I; yoke 24 is driven in simple harmonic motion by a linkage arrangement 25, 26 as in Fig. 2. The eccentricity of link 26 with respect to disk is made capable of variation as in Fig. 2, in order to vary the amplitude of the stroke or vertical reciprocation of framework 4. In this case, pulley ordisk 25 is fixed to a countershaft 66 which is horizontally positioned and is supported from support I. Motor I4 drives shaft 66 at'a suitable speed by means of a drive belt 68 which engages a pulley 6! attached to said shaft, a suitable speed-reducing mechanism 69 being interpositioned between motor I4 and belt 68.
f Outer framework 4, and therefore also inner frame 6 and jar 8, are rotated about a horizontal axis by means of a drive belt III, which drivinglyconnects' a pulley II keyed to countershaft 66'with a pulley I2 keyed to shaft 3 which is integral with outer framework 4. In order to allowfor vertical movement of members 2 I, and therefore also of shafts 3 and pulley I2, a belttightening pulley I3 is used on belt III.
- Innner frame 6 and jar. 8 are horizontally vibrated or reciprocated by means of actuating shaft III which extends through a hollow shaft 3 and the'inner end of which is attached to frame 6 by means of bearing 9. The shaft I0 is horizontally vibrated or reciprocated by a mechanism to be described below. A worm 'gear I4 is keyed to countershaft 66 near the outer end thereof, said worm engaging and driving a worm wheel I5 keyed to a suitably-supported and journaled stub shaft I6 whose axis is at right angles to that of shaft 66, shaft I6 also having keyed thereto a pulley II. A pulley 18 is journaled in a bearing which is attached by a suitable bracket I9 to one of the sliding members 2I. A belt drives pulley I8 from pulley II. In order to allow for vertical movement of pulley I8 as-a result of vertical movement of member 2I to which said pulley is fixed, a belt-tightening-pulley8I is used on belt 80.
A rigid link or crank member 82 having an elongated longitudinal slot 83 therein is pivotally fastened eccentrically to pulley I8 by means of .a pin 84. The eccentricity of pin 64 with respect to pulley I8 is made capable of variation, as in Fig. 1, in order to vary the amplitude of horizontal vibration of frame 6. A pin 85 is fastened to bracket I9. above and vertically aligned with the axis of rotation of pulley 18, said pin being engaged in slot 83. A pin 86 is fastened to the outer end of shaft I6, thispin also being engaged in slot 83. As will be apparentto those skilled in the art, the linkage mechanism 82-86 above described produces horizontal reciprocating motion of shaft III (and also of frame 6 and jar 8) when pulley I8 is rotated. 'It will be apparent, from the above description of the structure of Figs. 9-10, that horizontal reciprocatory, vertical reciprocatory, and rotary motions are simultaneously imparted to jar 8. By this apparatus, an extremely'efiective pulverizing action is produced, and the above-described advantages of simultaneous vibration and rotation of a ball mill are obtained to a greatly enhanced degree;
In the apparatus of Figs. 9-10, as in other figures, the mechanically vibrating systems are driven at their resonant frequencies, these frequencies being determined by the masses of the respective systems and the stiifnesses of their respective mountings, so that the desired minimum amount of power is all which must be utilized to maintain the vibrating systems in vibration.
Of course, it is to be understood that this invention is not limited to the particular details as described above, as many equivalents will suggest themselves to those skilled in the art. It is accordingly desired that the appended claims be given a broad interpretation commensurate with the scope of this invention within the art.
What is claimed is:
1. In a comminuting machine of the class described, a container for the material to be comminuted and loose pulverizing elements, said container being supported for rotary and vibratory movement, a vibratile body supported for compensatory vibratory movement with the container, resilient means mediate said container and said body, said means being disposed in the plane of the axis of rotation of the containerand the axis of the body, means for rotating saidcontainer and means'for inducing vibratory movement of said container and said body in said plane at natural resonant vibratory frequency.
2. In a comminuting machine of the class described, a pair of containers for the material to be comminuted and loose pulverizing elements, said containers being supported for rotary and vibratory movement, resilient means mediate the vibratory movement thereof in said plane at natural resonant vibratory frequency.
3. In a comminuting machine of the class described, a container for material to be comminuted and loose pulverizing elements, said container being supported for rotary movement and forvibratory movement along the axis of the rotary movement, a body of a mass substantially corresponding to the total mass of the container and its contents supported for compensatory vi bratory movement along the axi of rotation of the container, resilient means mediate said body and said container and forming therewith a vibratory system, means for rotating said container and means at one end of the system for inducing vibratory movement of said container and said body along their common axis at natural resonant vibratory frequency.
4. In a comminuting machine of the class described, a pair of containers for the material to be comminuted and loose pulverizing elements, said containers being supported for rotary movement along a common axis and for vibratory movement along said axis, resilient means mediate the containers and forming therewith a vibratory system, said resilient means being disposed on the line of said common axis, means for Totating the container and means at one end of the system for inducing vibratory movement thereof along said axis at natural resonant vibratory frequency.
RICHARD S. ROBINSON.
REFERENCES CITED The following references are of record in the file of this patent;
UNITED STATES PATENTS Number Name Date 195,120 Golding Sept. 11, 1877 395,680 Summerton Jan. 1, 1889 1,148,651 Beaumont Aug. 3, 1914 1,115,531 Hardinge Nov. 3, 1914 1,997,499 Shieferstein et a1. Apr. 9, 1935 FOREIGN PATENTS Number Country Date 347,413 Great Britain .Apr. 30, 1931 180,743 Switzerland Feb. 1, 1936 708,694 Germany July 26, 1941 870,798 France Dec. 22, 1941 251,491 Switzerland Sept. 16, 1948 OTHER REFERENCES Die Chemische Technik 15 Jahrgang, No. 18, Seiten -204, September 5, 1942, pages 195-198.
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|U.S. Classification||241/175, 451/328|
|International Classification||B02C17/14, B02C17/00|