US2424955A - Tumbling mill - Google Patents

Description

Jul 29,1947. v P, J, P TTER 2,424,955

.TUMBLING MILL I Filed Sept. 26, 1944. 6 Shee"gs-Shet 1 RewcyJmW/a P. J. POTTER TUMBLING MILL July 29, 1947.

Filed Sept. 26, 1944 s Sheets-Sheet 2 R WW Ma A M a m @f "H m P a MW w a HW M 7%,.) w E m o m 7 H m 9 m 1 a v 1 6 V a .7 M a a I y 29, 1947- P. J. POTTER TUMBLING MILL Filed Sept. 26, 1944 6 Sheets-Sheet 3 P. J. POTTER July v29, 1947.

TUMBLING MILL Filed Sept. 26, 1944 s Sheets-Shet 4 W W R m y 9, 1947. P. J. POTTER I TUMBLING MILL Filed Sept. 26, 1944.

6 Sheets-Sheet 5 July 29, 1947.

P. J. POTTER TUMBLING MILL Filed Sept; 26 1944 6 Sheets-Sheet 6 k PERCY J PD77EA",

Patented July 29, 1947 UNITED STATES PAIENT OFFICE Pangbom Corporation, Hagerstown, Md., a corporation: oi? Maryland Application September 26, 1944;. Serial No. 555.341

12' Claims.

1 I The present invention relates to tumbling" mills and more specifically pertainsto apparatusof this type wherein articlesare: tumbled and subjected to the action of a forceful streamoiabrasive particles.

An object of the present invention resides in providing atumbling mill wherein-the disadvantages attendant the use of. an endless conveyor for moving. the articles to ositions for tumbling downwardly are completely avoided and toprovide apparatus for handling a group of articles to be blasted wherein the moving partsof the tumbling mill are reduced to a minimum.

Another object ofthe invention resides in.- providing a tumbling mill wherein a'blast stream is established and the articles tobe subjected to the blast stream are shifted and elevated. as a group to a position laterally .of the blast stream and permitted to cascade through the'blast stream whereby theabrasive particles movingsatblasting velocitiesefiiciently impinge on theisurfaces o l? the articles passing through the blaststream;

A more specific object of the inventior-rzresides inpro-Viding a tumbling mill whereinthe articles to be blasted are arranged within arigid-drum which is oscillated through a-limitedrarctotumble the articles therein, includingmeans'for'projecting a blast stream into the drumprovided with novel means for controlling the operative period of the blasting means. i

A more detailed object of the invention; reside in providing a tumbling mill formed: of alrigid drum for receiving and tumbling the articles therein, including an abrasive throwing wheel mounted on the drum so as to-move therewith during the oscillation of the drum, including means for controlling the feeding of abrasive to the throwing wheel and the quantity of abrasive supplied to the wheel to thereby control the initiationand interruption of the blast stream pro jected by the abrasive throwing wheel.- I

Other objects and features of the invention will be apparent as the present disclosure proceeds and upon consideration of the accompanying drawings and the following detaileddescription wherein .anexemplary embodiment of the invention-is disclosed.

In the drawings: a

Fig. 1 is a side elevational view of a tumbling mill embodying the invention and showing-means forreturning the spent abrasive to a position for re-use in the apparatus.

. Fig. 2 is an end elevational ratus shown-in Fig. 1.

Fig. 3 is a'sectionalview taken on view of the apps the line 39-3 of Fig. 1 showing the driving mechanism for the drum.

' Fig. 4 is a sectional view of the drum: taken on the line 4-4 of Fig. 1.

Fig, his asectional view in-side elevation taken along the axis of the drum and the supporting shaft therefor.

Fig. 6 is a sectional view of the valve mechani'sin for controlling the flow of abrasive from the storage hopperand taken on the line 66 of Fig. '7.

Fig; '7 a sectional view of the valve mechanism' taken on the line-T-l of Fig. 6.

Fig. 8 is a sectional view of the connection between the operating arm and the shaft of the valve mechanism.

Fig-9: isa diagrammatic sectional view of. the drum taken: approximately on the: line 9-.9 of Fig. 1 illustrating one operatingv position.

Fig. 1 0: is a similardiagrammatic sectional view of the drum showing an exemplary operating condition. when the blast stream is initiated.

Fig. 11 is another diagrammatic sectional view illustrating an operating characteristics when the articles cascade in the drum.

Fig. 12 is a diagrammatic sectionalview illustrating another position of the drum in an exemplary' operating cycle.

.Fig. 13' is ajsectional view taken on the line l3--l'3 oiFig. 1 showing a portion of the hopper for receiving the abrasive discharged from the drum.

A tumbling millexhibiting: the invention is so designed that the articles tobe blasted maybe introduced" into a drum through an opening. in the periphery thereofa-fter which the drum is oscillated about the axis thereof through a limited arc whereby the articles are moved with the drum to a position for cascading downwardly therein. In apparatus embodying the invention the oscillating movement is automatic and: the drum is reciprocated. until theblasting operation is: completed. In an exemplary operating cycle the drum. oscillates through an arc of approximately one hundred and forty degrees, but it will be appreciated that the extent of the oscillating movement may be adjusted without departing from the-,metes and bounds of the invention hereinafter-described. in detail and defined in the claims. In the exemplary operating cycle, the abrasive -pro'jecting device is operable during a portioniofthe oscillating movement of the drum, and the blast stream is-maintained during. ap:- proximately a ninety degree movement of the drum; but it will-be appreciated that this oper walls of the drum. The imperforate end walls 1 II and I2 of the drum are secured to the bylin drical portion in any well known manner so' as to completely close the drum. The drumv may be supported for rotation about its axis in any suitable manner and in the embodiment illus- 4 as to permit movement of the drum III to a loading station with the opening 22 in a generally upper position and arresting the drum in such a position to permit loading of the drum. After the articles to be blast treated are ready for re- 7 moval from the drum, the motor 24 may be rotated beyond the normal oscillating limits to move the jdrum l0 to=a position, with the opening 22 in adownward direction whereby the articles will drop therefrom. It will be observed that the drum I0 is mounted above the floor or supporting base indicated at 34, so that a tote box or other conveyance may be positioned under the drum 10 for receiving the articles discharged therefrom through the door opening 22.

The invention includes any means for projecttrated the drum I0 is provided with a hollow shaft I4 extending axially from the end wall l2.f'

The connection between the shaft l4 andith'ek end wall i2 is reinforced by means of brackets IT, as shown in Fig. 5. The shaft i4 is rotatably mounted in bearings l8 and 19. These bearings are suitably supported so as to sustain'the load of the drum I ll and the castings'therein. The bearings IQ, for example, may be supported by means of a transverse beam 2| extending through a housing enclosing the driving mechanism for the drum.

The drum I0 is provided with an opening 22 in the periphery thereof throughwhich the articles to be treated or blast cleaned are introduced into the drum. The opening'Z'Z is closed by means of a door or arcuate plate 23 which conforms to the curvature of the drum. The door 23 may be securely maintained in the closedposition in any conventional manner and the details of the clamping means are well knownin'the art..' The drum l0. may be rotated 'so as..t0 position the opening 22 in'a' generallyupper positionwhereby articles to be treated within the drum may be introduced downwardly through the opening 22'. Such a position of the drum lllis shown in Fig. 12 V I" The drum I I] is oscillated by rotating the shaft l4. Any suitable driving "arrangement maybe provided for rotating the shaft. l4 and oscillating the drum. In the embodiment illustrated} the shaft (4 is driven by meanslof an electric motor M mountcd within the' housing '20; {The motor 24 maybe provided with'a pulley or'tsheave 26 about'which' a plurality of V-belts ZI'aretraine'd, and which drive a suitable sheave or pulley? of a speed reducing mechanism 29. The'speed reducing mechanism is mounted in a lower portion of the housin'g '20 and maybe of any-con ventional type. The output shaft3| of tnesp ed reducing mechanism drives" a chain 32 which is trained about a sprocketwheel '33 secured'to the shaft Id. The motor 24 is mounted in the upper portion of the housing 2t] so as to be movedand tighten the belt or belts 21. In the arrangement illustrated the motor is secured to a base plate 3 II.' This plate is hingedto' the housing 20 and maybe caused to swingupwardly so as to tighten the belt or belts 21 by means of bolt arrangement bw tfi I f M The motor is of the reversible :type and may be controlled in a conventionalmannerso asfto rotateth drum l0 in'one directionthroughian arc of approximately one hundredand forty d'egrees-, whereupon the direction of rotation or the motor is reversed and the drum" l0 rbtates infan oppositei'direction through an arc of approxi-' mately ne hundred 'and forty degrees. The elcf triccontrol for the motor 24 may be so' designed ing a blast stream into the drum. In the embodimerit illustrated, the abrasive projecting means takes the form of an abrasive throwing wheel represented diagrammatically at 36 in Fig. 10. The abrasive throwing wheel may be of a conventional directional control type for projecting abrasive particles from the periphery thereof, and the details of such abrasive'throwing wheel are disclosed in the patent to Keefer, No. 2,320,364.

The abrasive throwing wheel is enclosed within a protecting housing '31. The wheel 36 is supported for rotation in any suitable manner. In the embodiment illustrated, an electric motor 38 is rigidly attached to the protecting housing 31 and drives the wheel. This housing 3'! is rigidly secured to the periphery of the drum Ill. The base portion of the housing 31 is accordingly provided with a flange assembly 39 which may be bolted or otherwise secured to the drum It. The periphery'of the drum is provided with an elongated slotor aperture 4!, as shown in Fig. 10, through which the abrasive projected by the throwing wheel 36 enters the drum Ill.

The wheel 36 is driven by the motor 38 and both bodily move with the drum Ill since the housing 37 encasing the wheel and supporting the motor, rigidly attached to the drum. The motor 38 may be supplied with electrical energy in any appropriate manner, and in the illustrated embodiment electrical conductors 40 extend through the'hollow shaft l4, and power is supplied to these conductors through slip rings 42 arranged at the free end of the shaft to rotate therewith. This arrangement simplifies the problem of supplying electrical energy to the moving motor 38, and in view of the fact that the motor 38 moves with the shaft I4, no problem of cable wear is encountered-sincethere is no flexing of the conductors 40 which extend through the hollow shaft 4. The drum It] is provided with a projection or lug extending'inwardly from the arcuate wall so as to positively move the entire load. or group of articles with the drum during rotation thereof. Such a projection is shown at 43 in the drawings and is preferably of an inverted V-shape and extends inwardly from the inner wall of the drum Ifl so that the apex thereof defines a lip positioned inwardly from the periphery of the drum at a point approximately one-half the radius of the drum. The projection 43 is accordingly formed with the flat sides which merge witht'ne inner wall of the drum and may be welded thereto, The log or projection 43 extends throughout the length of the drum I0 as will be apparent from a consideration of Fig. 5. The apex'portion of the projection terminates in a lip which defines the innermost edge of the projection. Thus all of the articles forming a normal load within the drum are positively movedwith the drum and the projection formsa part of the support for the articles when the drum moves into the position shown in Fig. 10. It will be observed'that all of the articles are moved and supported as a group in this elevated position. As' the drum continues to rotate, the angle of repose of the articles is exceeded for some. of the articles and these cascade downwardly in the drum to the opposite side of the projection 43 as shown in Fig. 11. Further rotation of the drum causes theprojection 43 to move therewith until eventually all of the articles are supported 0111211 incl-inedsu-rface provided by one of the flat sides of th projection 43 whereupon these articles cascade downwardlyto the opposite side of the projection as illustrated. in Fig. 12.

The projection 4-3115 hollow for the purpose of receiving the spent abrasive from the drum. The flat 'walls of the projection 43 are therefore-pro vided with openings 44 through which the spent abrasive particles move to a position within the hollow projection. A partition 46 is arranged within the projection 43 to limit circumferential shifting of the abrasive upon oscillation of the drum. The drum periphery is provided'with apertures 4! through which thezabrasive-within the hollow protuberance 43 may escape through'the periphery of the drum, The abrasive disposal arrangement includesa trough 49 attachedto-the drum outwardly of the apertures 41. This trough may be Welded to the outside of'the drum and extends from one end thereof to the other, as shown in Fig. 1. The trough 49 is provided with inclined end walls 5! and 52 which diverge away from each other in proceeding towards the end wall l2 which is adjacent the housing 20'. The trough 49 extends beyond the end wall I2 of -the drum H], as will be apparent from a consideration of Fig. 5, so as to convey the abrasive to a position within the housing '25. This end portion of the drum is also provided with an annular flange 53 of substantially the same circumference-as the periphery of the trough 49', so as to provide for a continuation of the drum beyond 'the end wall H2. The annular flange 55' is concentric with the axis of the shaft l5, and this portionextends through an opening in the housing 20'. The'housing is provided with an annular gasket assembly shown at 5A for sealing the periphery of the drum with respect to the stationary housing 20,

The abrasive projected into the drum escapes through the openings 44 to a position within the hollow projection 43'. The abrasive then moves through the apertures 41 into the trough 49'. As the drum is rotated, the abrasive shifts circumferentially within the trough 49 and engages one of the end walls 5! or 52 so as to be supported on one of these walls. The trough 49 when arranged laterally of the axis of the drum provides that one of the end walls 5| or 52' presents an inclined surface down which the abrasive moves so as to be conveyed axially of the drum and into the housing 20.

A hopper 55 for receiving the abrasive is provided within the housing '20-. Thishopper is formed by inclinedplates 54a and 56, as shown in Figs. 13 and 5. A further inclined side wall 51 may be provided within the housing 20-. The" abrasive deposited in the hopper 55 is isolatedfrom the driving mechanism by means of a .par-

extends. Theperiphery of the-shaft l4 may be sealed with respect to the partition 58 by means of a gasket assembly shown at 59. Thus the "abrasive and the dust escaping from the drum the elevator.

60 through the tr'oughlil'isconfined to that portion of the housing 20 encasing the hopper 55. The abrasive discharged over the end Bl of the trough 49 drops ontothe inclined side Wall 56 of the hopper 5:5 and moves downwardly therealong and downwardly along the inclined side wall 54a.

The apparatus includes means for returning the abrasive "within the hopper 55 to a position for flowing, to the abrasive projecting means or abrasive throwing wheel 35. An elevator is shown. generally at 62' and includes an endless band or 'belt 53* whichis trained; about a pulley 64 :mounted for rotation in the lower portion of the: hopper 55. The endless belt or band 63 is provided with buckets or cups 66 for carrying the; abrasive upwardly with the belt 63. This belt may be driven by v means of a motor 5'! which drives a pulley 68 rotatably mounted at the top portion of the elevator through a suitable transmission mechanism indicated generally at 69. The hopper '55 may be provided with a shield member 11' so as. to prevent the abrasivefrom obstructing movement of the endless belt 63 of The shield H terminates short of the bottom of the hopper as shown in Figs. 5 and 1'3-so' that the abrasive may pass thereunder to aposition fOr being scoopedup by the elevator buckets 5-5. The-abrasive is discharged from the buckets or cups 66 and passes downwardly into a'separ'ator 12 which functions to remove foreign matter from the abrasive, and the cleaned abrasive particles move downwardly from the separator T2 into astora e hopper I3. The storage hopper 13 may besupported in any uitabl a nor above the drum: 15, such as by means of standards M,

A tumbling mill "exhibiting the invention includes means for controlling the movement of abrasive from the hopper 'lii'to the abrasive projecting device. Any control arrangement may be provided for permitting the abrasive tomove from the hopper 13 to the wheel 3'5 in timed relationship with the oscillation of the drum. An efiici'en't mechanism requiresthat a minimum quantity of abrasive should beprojected onto the arti cles within the drum, and it has been found that the blast Stream need only be established immediately prior to the tllmlblin'g or cascading of the articles so that these articles fall through the blast stream to provide good blast cleaning. This limited projection of the abnasivereduces the quantity of abrasive projected and thereby reduces the power required to propel the abrasive and the power required to elevate the spent abrasive. An exemplary arrangement for controlling the initiation of the blast stream projected by the abrasive propelling device includes the feature of supplying a limited quantity of abrasive to the wheel 3550 that the blast stream projected thereby is interrupted when the'measured quantity of abrasivesupplied to thevvheel is exhausted. An arrangement embodying these features includes a unique feed spout I6 for the wheel for receiving a limited quantity of abrasive. It will be ob served that the 'feed' spout 16 is formed with a relatively large opening at the top so as to receive abrasive from the hopper 13 as the wheel assemlbly passes theoutlet for the abrasive. The feed spout- T6 is arranged'to supply abrasive at the axis of the wheel 365whereby the abrasiveis pro-,

jected from the periphery in a well known manner as is described in the patent to Keefer No. 2,320,364.

The abrasive control includes a valve assembly shown at 11 for permitting the escape of abrasive from the storage hopper 13 into the feed spout 16. This valve assembly comprises a sector shaped member 18 which is mounted for swinging movement by means of two axially aligned shafts wand 88 which are journalled in the side walls of the valve assembly. The sector shaped member I8 is so designed that the abrasive escaping downwardly from the hopper 13 through the outlet opening 8| will be interrupted when the sector shaped member 18 is in the position shown in Fig. 6. The shaft 80 is biased so as to move the sector shaped valve member 18 to the valve closing position by means of a spring 82 which is attached at one end to a fixed bracket 83 and attached at the other end to a lever 84 rigidly secured to the end of the shaft 80. The shaft 19 is provided with an arm 86 for the purpose of moving the valve to an open position against the action of the spring 82 and thereby permitting the abrasive to escape downwardly into the feed spout 16 when this feed spout is positioned under the discharge spout 81 of the valve assembly.

The invention includes means for actuating the arm 86 so as to open the valve when the feed spout 16 is in aposition to receive abrasive from the hopper 13. Such means may comprise a cam 88 mounted on the top portion of the wheel hous-- ing 31 so as to move therewith. The cam 88 is preferably provided with elongated slots 89 so that the position of the cam may be adjusted in relation to the wheel housing 31. The operative portion of the cam 88 may be adjusted in length by replacing the cam shown with one having a longer or shorter cam portion to thereby vary the period during which the valve is open. As the drum Ill rotates in .a counter-clockwise direction, the cam 88 will engage the lever arm 86 and turn the shaft 19 and the shaft 80 against the action of the spring 82, so as to move the sector shaped valve member 18 to an open position and thereby permit abrasive to flow from the funnel 81. The arm 86 is provided with a roller 85 for being engaged by the cam 88. In the embodiment illustrated, the wheel housing 31 is then in a substantially vertical position, as shown in Fig. 10, and the abrasive will drop into the feed spout .16. This flow of abrasive will continue as long as the cam 88 remains in engagement with the arm 86. After the terminal portion 9| of cam 88 passes beyond the arm 86, the spring 82 will return the sector shaped valve member 18 to the closed position and interrupt the flow of abrasive from the funnel 81. The cam 88 is therefore short enough to permit closure of the valve before the enlarged feed spout 16 passes to a position laterally of the funnel 81.

The wheel 36 is accordingly supplied with abrasive when the cam 88 opens the valve 18 and a blast stream 92 will-be initiated when the drum arrives approximately in the position shown in Fig. 10 in moving in a counter-clockwise direction. The abrasive throwing wheel 38 will propel the abrasive and maintain the blast stream 92 after the valve 18 is closed, since a quantity of abrasive will be stored in the enlarged feed spout E6. The drum ID in moving further in a counterclockwise direction to the position shown in Fig. 11 will cause the wheel 35 to move therewith and the abrasive within the feed spout 1'6 will be supplied to the wheel and the abrasive blast stream 92 will be maintained. The blast stream 92 will be interrupted when the abrasive within the feed spout 16 has all passed through the wheel 36. The point at which the blast stream 92 is interrupted in relation to the oscillated position of the drum l8 may be varied by adjusting the quantity of abrasive supplied to the feed spout 16. The quantity of abrasive supplied to the feed spout 16 may be altered by varying the area of the orifice 94 provided in the valve assembly H and other parts of the valve assembly. The length of the cam 88 may likewise be varied to control the quantity of abrasive supplied to the hopper l6 and accordingly the duration of the blast stream 92. It is desirable that this blast stream be interrupted at the earliest possible moment during the counter-clockwise rotation of the drum ID in order to reduce to a, minimum the quantity of abrasive projecting into the drum I8, and this blast stream may be interrupted when the batch of articles have all cascaded over the projection 43. Thus when the drum l0 arrives in the position shown in Fig. 12, the blast stream has been interrupted.

The tumbling mill herein disclosed provides but one abrasive projecting device in the form of abrasive throwing wheel 36 and during the clockwise rotation of the drum in no abrasive is projected into the drum. As the cam 88 passes the arm 86, the valve member 18 is not moved from the closed position and this operating condition is made possible by means of a one-way clutch arrangement between the shaft 19 and the arm 86. This one-way driving arrangement includes a pin 96 extending through the shaft 19 and extending through a slot 91 in the arm 88. This slot 91 is so shaped and dimensioned that when the arm 86 is turned in a counter-clockwise direction in Fig. 8, the shaft 19 is not rotated and the'valve 18 remains closed. Thus no abrasive is supplied into the feed spout N as the drum moves in a clockwise direction.

During this clockwise rotation of the drum in the articles or castings represented at l 98 in Fig. 12 are all positively moved in a clockwise direction with the drum, and the projection 43 then acts as a pushing member. The articles or castings. are eventually elevated so as to tumble or tocascade over the edge of the projection 43 and then assume the position shown in Fig. 9 where the drum ID has arrived in its extreme clockwise position. The drum I0 is then reversed and the projection 43 causes the articles I to be moved with the drum as shown in Fig. 10. In other Words, the projection 43 extends inwardly from the wall of the drum for a distance sufficient for forming a pusher member when the drum is in the; position shown in Fig. 9, and all of the articles must move with the drum. As the drum l0 moves in a counter-clockwise direction into the position shown in Fig. 10, the projection 43 and one of the fiat sides thereof still act as a pusher. member and partly supports the load represented by the articles.

The wheel 36 is continuously rotated during the treatment of the articles in the drum i9, and when the drum has rotated int the position shown in Fig. 10, the cam 88 engages the arm 86 and turns the shaft 19 so as to move the valve member 18 to an open position permitting the abrasive to fall downwardly into the enlarged feed spout '55. This operating condition is shown in Fig. 10, and the abrasive blast stream 92 is established. At this time the article have assumed the position'shown in Fig..l0, and it will be noted that the blast stream 92 passes approximately through the center of the drum and engages the surfaces of the articles. As the drum I continues to-move in a counter-clockwise direction the articles are further shifted as a group to a position laterally of the axis of the drum and then are supported principally by the flat side of the projection-4% The apex edge portion of the inverted. V-shap'e' projection 43 then defines the limits of the supporting base for the articles. The articles therefore remain supported laterally of the axisof the drum until "the angle of re'poseis exceeded and thereafter the castings lllfl fall or cascade through the blast stream 92, as shown in Fig; 1 1. It will be noted that when the drum is in position some of the articles have not yet exceeded their angle of repose andare therefore still supported by the side of the projection-'43. Additional counter-clockwise rotation of the drum will cause these articles to beiurther' elevated before cascading through the blast stream. The cascading operation is-thusprotracted and the articles pass through the blast stream in a separated relationship with respect to each other whereby the articlesare more efficiently exposed to the impingement of the abrasive particles thereon. a

During the oscillation of the drum the spent abrasive particles sift through the openings 44 and through the apertures 41 into the trough 49, and these abrasive particles are then conveyed into the hopper 55 by one of; the inclined side end walls 5| or 52 of the abrasive trough, The spent abrasive particles arriving in the hopper 55 aremoved upward-1y by the conveyor 62 and are returned to the hopper 13 for re-use.

The e ar f d spout is r y supported on the protective housing 31 of. the abrasive throwing device, and the feed spout ifiathus bodily moves with the drum 1-0, As hereinabove described the flow of abrasive from thestorage hopper '13 is interrupted before the outermost edge 10 of the feed spout passes beyond a vertical plane extending through the outlet in the funnel 81. Thus all of the abrasive escaping.

from the storage hopper when the valve assembly TI is open is supplied into the feed spout 16. The wheel 36 being thus supplied with abrasive continues to project the blast stream represented at 9.2 into the drum during counter-clockwise rotation thereof from the position shown in Fig. 10 until the measured or limited quantity of abrasive within the feed spout I6 is exhausted. In view of the fact that the feed spout 16 moves with the wheel 36 and with the drum [0, a partition 93 is arranged within the feed spout having an inclined side wall 80a so that all of the abrasive in the feed spout will be delivered to the center of the wheel as the drum moves into the position shown in Fig. 11. The partition 93 and the inclined side wall 80a thereof prevents abrasive from lying on the side wall 90 of the housing 31 and all of the abrasive is thus eihciently delivered to the abrasive throwing wheel 36.

While the invention has been shown and described in connection with specific structural details of the tumbling mill it will be appreciated that changes may be made in the apparatus such as alterations in the driving mechanism and variations in the operating cycle such as the arc of oscillation of the drum l0, and variations in the duration of the blast stream during rotation of the drum. Such modifications may be made without departing from th spirit and scope of the invention as set forth in the appended claims.

I to

'1. a tumbling mill, a substantially cyliridrical drum, means supporting said drum for rotation about the axis thereof. an abrasive throwing wheel, means carried by the periphery of'the drum supportingsaid abrasive throwing wheel for rotation; means supplying abrasive to said abrasive throwing wheel, said drum having a, an opening in the periphery thereof through 10- which the abrasive projected "by the wheel enters the drum and means controlled by the movemen-t of the drum for interrupting the supply of abrasive tosaidwheel.

"A tumbling -mill gomprising, a drum mounted for rotation about the axis thereof, an abrasive throwing- -wheel,' means supporting said abrasive throwing wheel on the periphery of the drum, means-rotating the abrasive throwing wheel, a stationary hopper fora supply of abrasive-particles, and meansfor admitting a limited quantity of abrasive-particles from saidsupply-hopper to the presence of the wheel during rotation. of the 3. A tumbling mill comprising, a drum, means for rotating said drum, an abrasive throwing wheel, means carried by the periphery of the drum supportingsaid wheel for rotation, means rotating :the abrasive throwing wheel a feed spout movable with the wheel, a hopper for stora supply of abrasive particles, valve. means normally obstructing the flow of abrasive from said hop per, and :means actuated by movement of the drum f r ope insf ai va ve me ns when. said feed-,spoutisfin a position to receive abrasive from said hoppe .4, A tumbl ng i l comp isi a means or rot ting'sa .clrum, an abrasive throwin h 1,.m ns carri d by t e eriphery of the u su po ting said heel. fo rot tion m ans r tating the; abra ive throwing wheel, a feed spout movable wi h the whe l, a hopper for sto ihsa supp ofabrasive parti le a valve normal y ebstrubtins h new of abrasiv from said hopper, a cam movable with the drum ior opening said valve when the feed spout is in a position .to receive abrasive from the hopper, and means returning said valve to a closed position before said feed spout moves beyond the path of the abrasive flowing from said hopper.

5. A tumbling mill comprising, a drum, means for rotating said drum, an abrasive projecting device mounted on the periphery of the drum so as to move therewith and direct a stream of abrasive substantially diametrically into the drum, means for supplying abrasive to said abrasive projecting device, and means for interrupting the supply of abrasive controlled in accordance with the position of the drum during the rotation thereof.

6. In a tumbling mill, a substantially cylindrical shaped drum, an abrasive projecting device mounted on the drum and movable therewith so as to direct a blast stream into the drum, a projection carried by the drum and extending inwardly from the peripheral wall thereof termimating in a lip located sufliciently inward from the peripheral wall to positively move a group of articles with the drum, means for rotating the drum, and means controlled in accordance with the position of the drum for initiating the blast stream projected by said abrasive projecting device.

7. In a tumbling mill, a substantially cylindrical shaped drum, an abrasive projecting device mounted on the drum and movable therewith so 11 as to direct a blast stream into the drum, a projection carried by the drum and extending inwardly from the peripheral wall thereof I termia nating in a lip located sufiiciently inward from the peripheral wall to positively move a group of articles'with the drum, and means rotating the drum whereby the projection in cooperation with the drum moves the articles as a group to an elevated position Where they cascade downwardly through the blast stream.

8. In a tumbling mill, a drum, means for projecting abrasive particles into the drum, said drum having apertures therein through which the spent abrasive particles may escape from the drum, a trough carried by the periphery of the drum receiving the abrasive particles passing through said apertures, end walls for said trough diverging from each other in proceeding towards one end of the drum for conveying the abrasive therein to one end of the drum, a housing, an annular flange around the drum intermediate the end walls of the trough, and agasket assembly sealing the housing with respect to the peripheral portion of the trough and with respect to said annular flange. v v t 9. A valve assembly for controlling the supply of abrasive to a projecting device of a tumbling mill comprising, a movable valve member, a shaft for moving the valve member, an operating arm,

and a one-way clutch between the operating army and said shaft.

10. A valve assembly for the storage hopper of' a tumbling mill comprising, a sector-shaped valve member for obstructing an outlet of said hopper, a shaft supportingsaid valve member for swinging movement to an open position, resilient means biasing said valve to a position obstructi said hopper outlet, an operating arm rotatable on said shaft, a pin carried by the shaft, and said operating arm having a. slot therein or limited circumferential extent whereby an end wall of the slot engages the pin upon swinging movement of the operating arm in one direction to rotate said shaft and swing th closure in the valve member to an open position. I

'11. In a, tumbling mill, a drum for receiving articles; means for rotating the drum, a proj'eca tion extending inwardly from the arcuate wall of the drum to, a position for positively moving substantially all of said articles with the drum, an abrasive projecting device carried by. the drum directing ablast stream in a chordal direction into the drum to one side of the p rojection where- 'by the blast stream moves with the drum and the articles cascade through the blast stream when they exceed their angle of repose with reference to the inner edge of said projection.

12. In a tumbling mill for blasting a batch of articles and in combination, an oscillating drum, an abutment projecting inwardly from the inner wall of the drum and extending from end to end thereofand of a width substantially the same as the depth of the batch of articles .placed in the drum for treatment, means movable in synchronism with the drum for propelling into the drum, in a chordal direction, a. blast stream having an oblong impingement pattern with its longer axis substantially parallel-to the axis of the drum, and means for moving the drum about its axis for causing theabutmentto move laterally and upwardly the batch of articles to successively bring portions thereof above the angle of repose and cause the same to progressively cascade through said stream.

. PERCY J. POTTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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