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Feb. 8, 1938. w, |_, KEEPER 2,108,005 ABRADING APPARATUS Filed July 25, 1935 2 Sheéts-Sheet l i 3 W0 MM Millie/L. ffi’efer Feb. 8, 1938. _ w_ L KEEPER 2,108,005 ABRADING APPARATUS Filed July 25, 1935 2 Sheets-Sheet 2 27 Patented Feb. s, 1938 2,108,005 UNITED STATES2,108,0052' PATENT OFFICE ; ABRADING APPARATUS Walter L. Keefer, Hagerstown, Md., assignor to Pangborn Corporation, Hagerstown, Md., a cor poi-anon of Maryland Application July; 25, 1935, Serial No. 33,185 ‘ 6 Claims. The present invention relates to abrading ap paratus and it is more particularly concerned with mechanical abrasive projecting ‘or propelling ' 5 (Ol. 51-9) peller blade securing plates has been removed to show a part of the blade securing means. Figure 2 is a sectional view taken substantially , machines of the character wherein an‘ abrasive on line 2-2 of Figure 1, and it shows’ one of. the v is projected by centrifugal action against the propeller blades in section. _ Figure 3 is a transverse sectional view through - work operated upon. A primary object of. the present invention is to provide a machine having all of the desirable characteristics of the successful abrading ma 10 chine shown in copending application Serial No. the base of the impeller shown in Figure 1 and illustrates the parts as they appear when‘ viewed from the right-hand side of that ?gure. ‘726,188 together with further highly desirable structural and operating features that improve the wearing qualities, life and efficiency of the mechanism materially. to Figure 3 but the section is taken through the peripheral ?ange of the cage holder of Figure '1. Figure 4 is a right-hand end view (Figure l) of the feeding cage with its associated parts re It is a' major object of my invention to provide a novel centrifugal abrading machine that will ef?ciently utilize all of the abrasive supplied thereto, and have a long useful life in service, which issc- constructed as to provide ready dis assembly for servicing, and yet‘ which is low in moved therefrom. cost. . . It is a further object of. my invention to pro vide a centrifugal abrading machine having im peller and propeller blades which are properly correlated to produce a uniform flow of abrasive to the propeller blades and to reduce the initial impact of‘ the abrasive therewith and the abra sive wear thereon, while improving the abrasive curtain discharged therefrom by increasing its concentration and reducing the stray abrasive discharge. 31 ' It is another object of this invention to provide a novel abrasive feeding assembly for centrifugal abrading machines in which the need for com-' plicated and expensive air and abrasive seals is obviated. ' ' . A further object of this invention is to pro vide an abrasive feeding unit of novel design for abrading machines which may be readily re moved from the machine as a unit without dis turbing any of the parts thereof. My invention also aims to provide centrifugal abrading machines with an improved abrasive impeller assembly and generally to re?ne and im prove other features of such machines. Further objects of the present invention will become apparent as the detailed description thereof proceeds in connection with the annexed drawings, and from the appended claims. In the drawings: Figure 1 is a longitudinal sectional view of a centrifugal abrading machine embodying my in vention and it is taken approximately on the line l-l of Figure 2. In this view oneof-the pro Figure 3A is a sectional view somewhat similar '_ - 15 Figure 5 is a fragmental top plan view of the bracket which holds the feeding assembly in position in the device shown in Figure 1. Figure 6 is a fragmental sectional view some what similar to Figure 2, but illustrates a modi 20 ?ed form ofv cage and impeller assembly, also forming part of the invention. With continued reference to the drawings, wherein like reference characters are employed to designate like parts throughout the several 25 views thereof, the machine is supported upon a base designated generally at l0 and which pro vides an opening through which the blast wheel or runner assembly projects. ' Mounted upon base I0 is a runner wheel hous ing designated generally at H and which com prises end walls l2 and. I3, side walls l4 and I5, and a cover l6 which is hinged to the housing in a manner to be presently described. Abrasive guard plates l1 and I8 are secured to sidewalls l4 and I5 respectively, by means of nut and bolt assemblies I9. Base I0 is provided with a mem ber 2|] having an opening filled with lead 20’ or any other renewable material. A further re inforcing guard plate 2| is secured to plate H 40 by means of a nut and bolt assembly 22. An abrasive vguard plate 23 is also secured to the lower side of lid l5 by means of nut and bolt assemblies 24. Housing top or lid I6 is hingedly connected to 45 the housing for ready access to the interior by means of a hinge comprising a .pair of. lugs 25 secured to the lid, a pair of lugs 26 secured to the casing and a pivot pin assembly 21. The lid is releasably held in place by a plurality of bolts 50 28 having special dustproof or blind-ended nuts 29 threaded thereon. Bolts 28 ?t through slots 30 in a pair of cross pieces 3| secured to lid l6, and are received with considerable clearance in lugs 32' secured to housing H so that nuts 29 need 2 2,108,005 merely be loosened and bolts 29 rocked out of slots 38 in cross pieces 3| to permit the lid to be lifted into opened position. — view of the fact that the velocity of the abrasive increases as it-approaches the outer end of the blades and accordingly'narrows down to a thinner ' Secured to side wall I2 of housing H by‘means ' stream. Hence the’blade is wider at its inner of nut and bolt assemblies 33 and angle brackets - end in order to insure that the abrasive will not ' 34, is an abrasive rebound guard 35 whose func tion will be pointed out hereinafter. A wear plate 38 is secured in place below the base in any suitable manner and carries an abrasive re bound guard 31. All of the rotatable parts'of the machine are ' carried upon a shaft 38,'which maybe mounted. for rotation in any suitable manner, but which ‘ is supported in the present instance by means of 15 ‘a pair of axially spaced bearings 39 which are‘ provided with arms 4| for securing them to the base. As. the shaft and bearing arrangement forms no part of the present invention, only one bearing assembly has been shown in order to 20 simplify the disclosure. escape laterally from the blade as it is initially contacting therewith and is in a less contracted condition. - ‘The mechanism I preferably employ for feed ing abrasive into the space defined by the inner 10 ends of the propelling blades will now be de scribed. ' ~ - a - ’ Bridging a semi-circular recess 88 provided in base I8 is an arm or bracket 81 which is pro vided with a forwardly and downwardly curv ing portion 88. ' Portion .88 is reinforced by means of a plurality of webs 10 which join it to arm 81. Arm 8‘! may be secured to base “l in any suitable manner, but I preferably employ a r pair of studs 89 which are secured in base I8 and 20 Power may be applied to shaft 38 in any suit which ‘extend through open-ended slots ‘H in able manner and it extends into housing H arm 81. Nuts 12 are employed to hold-arm 81 through an opening defined by notches 42 and ~ in place on base l8, and as seen in Figure 1 they , 43 formed respectively in base l8 and housing are preferably provided with closed ends to ex side wall l2. Supported on the shouldered end clude dust from the threads. Slots ‘H are dis 25 of shaft 38 is a heavy disc 45 and it is preferably posed with their open ends facing toward the keyed thereto in any suitable )con'ventional man ner. Disc 45 is restrained against axial displace ment from shaft 38 by means of a plate 48 which bears against the end face of disc 45 and is 'se cured to shaft 38 by two machine screws 41. The abrasive propelling elements of my ma chine are carried by a rotatable runner head or rotor 48 which is secured to disc 45 by a plurality _»_ of counter-sunk screws 49. Runner 48 is pro vided with a peripheral ?ange 5| which operates to restrain the abrasive propelling blades against rotor, so that when nuts '12 are loosened, bracket 81- may be slid to the right and removed. ' ,In order toinsure that arm 81 will be posi tioned properly when put in place over studs 30 89, it is preferably provided with a pairof posi tioning set screws 14 for cooperation with studs. 89, each having a locknut ‘l5 turned thereon. To properly adjust positioning screws 14, arm or bracket 81 is put in place on base l8, nuts ‘II are taken up lightly, and arm 81 is then by experi ment or measurement brought into the proper , outward movement in response to centrifugal force. The abrasive propelling blades are pref 40 erably four in number and are designated gener ally at B. Blades B are secured in place in pref erably symmetrical relationship on runner 48 in a manner similar to that employed in the afore said copending application, and with reference position. Nuts 12 are then taken up tight. Po sitioning screws 14 are then screwed up to take up the lost motion between them and studs 89,vv 40 and locknuts 15 are‘ then screwed into place to maintain the positioning screws in the proper set to Figures 1 and 2, four sector-shaped guide plates tially loosened and arm 81 is, being maneuvered 45 53 are secured in place on head 48 by means of counter-sunk screws 54, and their edges are bev eled so that adjacent sides of each pair of guide plates will form a dove-tail groove. The side 50 edge of each blade B is provided with a corre spondingly beveled face 55, so that when blades - B are inserted in the center of the machine and slid outwardly into position between the guide plates they will be ?rmly held against movement. Annular ?ange 5| prevents the blades from mov ing outwardly in response to centrifugal force and a bowed leaf spring 58, ?tting in a groove 51 provided in each blade, frictionally restrains each blade against inward movement. As the 60 blade restraining means forms no part of the present invention it will not be further described. Referring to the con?guration of the blades, position.‘ If desired, however, positioning screws - 14 may be manipulated while nuts 12 are par into proper position. The forward face of the curved portion 88 of arm 81 is provided with a circumscribing ?ange 11 having vertical and horizontal portions. Se cured to the forward face of portion 88 by three 50 nut and bolt assemblies 19 and having a rab beted portion 18 conforming to the ?ange of por tion' 88, is a holder 8|. Holder 8| provides a combined'spout and cage or distributor support. Holder 8| is accordingly stationarily but re 55 movably secured to base l8, and it is provided‘ with a preferably integral spout portion 82 which has an overhanging lip 83 for cooperation with the impeller in a manner to be hereinafter pointed out. Spout portion 82 is provided with a funnel or spout extension 84, and although these parts may be integrally formed, I preferably form I and with reference to Figures 1 and 2, each blade‘ ' .them in two pieces to facilitate casting of the 65 B is provided with a substantially ?at abrasive parts. They are fastened together by pairs of propelling surface 59, which extends from _.the_ lugs 85 formed on the respective members and outer end of the blade to a region near the inner end thereof. The inner end of each blade is nut and bolt assemblies 88. ' preferably provided with a curved abrasive pick into a cage or receptacle which is carried by up surface 8| for a purpose that will presently holder 8|, and which is designated generally at C. Cage C is provided with a generally cylindrical portion 81, a deep, preferably imperforate ?ange 88 anda shallower ?ange 9| in which four notches 70 appear. With reference to Figure 1, each blade (in this instance upper blade B) is provided with a pair of abrasive guiding ?anges 82 and 83. Flange 82 is substantially parallel to runner head 48 whereas ?ange 83 inclines toward the runner 75 head at its outer end. Flange 83 is inclined in .85 Abrasive introduced into spout 84 is conveyed 89 are provided. Notches 89 correspond in num ber and spacing to the blades of the impeller, to be described hereinafter. Cage ?ange 9| is pl n 3 9,108,005 loted or centered upon a cylindrical hub or ?ange 92 provided on holder 8|. Cage-C is also pro vided with a recessed face 98, and an element 98 covers slots 98 in holder 8|. Cage C is-preferably abrupt changes in a substantially radial direction" until it reaches the tips of. the blades. Blades IOI are also distributor blades as they serve to break up the abrasive stream entering cage C into a adjustably supported for angular rocking move readily distributable form, and to impart an in ment about the axis of the machine upon holder itial velocity to the abrasive prior to its being 8i in the following manner: _ picked up by the propeller blades, and the latter Preferably a pair of diametrically opposite studs 91 are secured in ?ange SI of cage C and extend through apertures in slot cover 84. Studs 91 extend through arcuately-shaped slots 98 in holder 8|, as shown in Figure 3', and a pair of. nuts 99 are turned thereon to releasably clamp cage C to holder 8|. As seen in Figure 1, nuts 99 are of special form as their ends are closed 15 to exclude dust and abrasive from the threads, and they provide “hex"_manipulating heads which are disposed a considerable distance from cage C in order that the nuts may be readily loosened and. manipulated during the cage adjusting op 20 eration. Nuts 99 also provide convenient operat ing handles which may be grasped for rocking cage C into proper angular adjusted position after they are loosened. Cage C is also pro-_ vided with a discharge slot or opening I00, which inclines forwardly with respect to the direction . of rotation of the runner, as seen in Figure 2. function to impart the ?nal abrading velocity to the abrasive, I have employed. this ter minology to differentiate these functions of the 10 two sets of blades. The impeller is assembled with the runner assembly in a predetermined relationship to- es tablish a highly important cooperation between‘ the impeller blades and the propeller blades for 15 feeding and propelling the abrasive in a novel manner. Referring to Figure 2, the direction of rotation of the runner is'counter-clockwise and it is seen that each impeller blade IOI- is dis-‘ posed at a predetermined angle of advance in 20 the direction of rotation of the runher with re spect to its propelling blade B. This relation ship is established between the impeller and pro peller blades so that -~the abrasive .which is “churned” around in cage C will be discharged 25 through slot I00 a predetermined angle in ad Vance of each blade B. This synchronized or co I preferably employ an impeller or agitator , within cage C which rotates synchronously with runner £8; for insuring a proper feeding of the 30 abrasive to the propeller blades B. The impeller. ordinated action of 'the impeller and propeller blades insures that the abrasive will be positively thrown out into the path of the propeller blades, 30 and by reason of the angular velocity component or agitator is preferably equipped with the same - of the-abrasive, and the rearward inclination of number of blades as are present on runner 40, v the inner ends of the blades, the abrasive is 35 40 and in the present case they are four in number. Impeller blades IOI are joined at one end by. a picked up with a minimum impact. cone-shaped cylindrical portion I02 providing a truncated cone-shaped internal abrasive feeding face, and into which lip 83 of spout 82 projects. from the wheel. Impeller blades IOI are also provided with concave faces I08 which face for Blades I0l are joined at their other ends by'a of the runner assembly so that the abrasive im generally cup-shaped member preferably pro viding a circular abrasive ballling ?ange I03, and a deep cylindrical ?ange or hub I04 in which a pair ‘of diametrically opposed slots I05 are formed. ' _ The impeller is preferably secured to the run ner assembly by means of a long cap screw I 06 which passes through an aperture in the cen tral part of the impeller and plate 48, andis threaded into shaft 38. Cap screw I 06 pulls the impeller with its ?ange I04 into tight engagement 50 with plate 48 and with its slots I05 embracing ‘the heads of machine screws 41. By reason of slots I05 in the impeller ?ange ?tting over screws 41, it is impossible to improperly assemble the impeller with the runner assembly, as these parts This also re sults in a more restricted or contracted discharge ‘ wardly with respect to the direction of rotation pelled thereby will be con?ned to the width of 40 the blades, and Will accordingly be discharged through slot I00 onto blades B in a more con tracted form. ‘By con?ning outward ?ow of the abrasive over blades B to a narrower lateral area, less power is required to drive the wheel. and the 45 discharge from the runner is of a more concen trated character. Operation The work is placed under the machine oppo 50 site the discharge opcning and it is to be under stood that the work may assume. various forms and may be moved in various ways while it is treated. For instance. the work may be located in a tumbling device or may be mounted on a mustbe in alignment before cap screw I06 may truck to be moved about under the machine to expose various parts to the blast. Moreover, the reference to Figure 1, ?ange I03 of the impeller work may be passed through a cabinet, and the extends outwardly beyond ?ange 88 of cage C, > machine mounted for oscillation about different with the result that they are radially overlapped axes in order to subject the work to the blast at 60 and abrasive leakage is minimized, because the various angles. Also, the work may be passed abrasive in cage C would have to take a tortuous ’ through a suitable cabinet or housing in strip or path in order to escape therefrom. In order to sheet form and subjected to the action of one orv minimize abrasive leakage over ?ange 9|, one more of my machines. If desired, however, the wall I01 of each of slots 89 formed therein is machine may be mounted in inverted relation beveled, and as seen in Figure 4 they are beveled ship in a cabinet to be directed against the lower in a direction to assist in maintaining the ab side of the work passed therethrough or it may rasive in cage C. ‘ ' be mounted to discharge horizontally or at an Although I have termed blades B “propeller” oblique angle. The following discussion of the be brought into its ?nal tightened position. With blades, and blades IOI “impeller” blades, their action upon the abrasive is somewhat similar because in each instance the abrasive is picked up by the inner end of the blades and is impelled or propelled outwardly over the blade and is 75 smoothly and continuously accelerated without operation of the machine is therefore intended 70 to apply to my machine irrespective of the man ner in which the work is exposed to the blast stream. - _ ' Shaft 88 may be rotated at any-suitable speed, but with a machine constructed as shown in-the 75 4 2,100,006 drawings, I ?nd that a speed of approximately 2500 R. P. M., in the direction indicated in Fig ure 4 is suitable for satisfactory operation of the machine. Cage C is mounted on holder 8| in the position shown in, the drawings at the fac tory, and it has been found that. with the pro Y ‘portions of the various parts as shown, and with‘ the discharge opening I00 located as shown in Figure 2, the discharge from the machine will be properly located when the machine is rotated at the proper speed. However, if it is found upon operating the ma chine that the .discharge is not directed as de sired, nuts 99 may be loosened and manipulated 16 to rock cage C and thereby change the angular relationship of abrasive discharge slot I00. As the point at which the abrasive stream leaves the wheel is determined by the point at which the abrasive is admitted to the inner ends of the 20 propeller blades, and as the time it takes for an abrasive particle to traverse the blade depends upon the length of the blade and to some extent upon the nature of the abrasive, it is apparent that by rocking cage C so as to vary the angular 25 position of slot I00, the angular range over which the discharge from the machine will occur may be correspondingly varied. and as the tangential component of the velocity of an individual particle of abrasive is not great ly lower than the velocity of the inner ends of blades B, wear of the latter is minimized. ' As the abrasive is forwardly rotated in cage C under the in?uence of impeller blades l0l it is con?ned by ?anges 80 and 9| and it will be seen that if any stray abrasive should leak be tween cage C and holder 8| and the sides of spacer member 94, the abrasive so escaping can 10 do no harm as it is located within housing H and hence will merely gravitate or be impelled out of the discharge opening thereof. Moreover, as these parts merely function as a funnel or chute for introducing the abrasive into the im peller, there is no tendency for an air or abra sive leak to develop due to the arrangement and location of the parts. It is accordingly unneces sary to provide an air or abrasive tight joint be tween the cage and the holder. In view of the fact that disc 45 and runner head 48 ,are permanent parts, as distinguished from certain other parts of the device, which are frequently replaced and hence are replacement parts, it is desired to completely protect these permanent parts against abrasion. The end of disc 45 is protected by wear plate 46, which may ‘ Assuming that the machine is properly ad justed, and the rotor has been brought up to 30 speed, .an abrasive of any suitable form, (prefer be replaced in a manner to be hereinafter de scribed when it has become worn excessively by stray abrasive. The impeller and cage and blades . ably metal grit) is preferably allowed to drop by - B >may likewise be replaced and in connection ‘gravity into spout 84, and it is preferably me tered as by means of a screw or other conveyor operating at a predetermined constant speed. 35 Rotation of runner head 48 causes blades B and impeller blades i0l to establish‘ a partial vacuum in the axially extending passage de?ned by the inner ends of the impeller blades and in the lower end of spout 84, so that the abrasive en tering the spout is picked up by a rapidly moving 40 air stream and enters the impeller with a pre determined degree of initial velocity. The abra sive is then impelled outwardly over concave por tions of the impeller blades, and when it reaches ' the blade tips it is “churned” around or agitated 45 within cage C. A dispersion of' air and abrasive which rotatesforwardly with respect to the di rection of rotation of the runner assembly is thereby established, and also a stationary or slow ly moving ?lm of abrasive lodges on the interior 50 of cylindrical portion 81 of cage C, and thereby protects it from excessive wear. Cage flanges 88 and 9| serve to con?ne the abrasive within the cage as it is being agitated. , The forwardly rotating dispersion of sand and 55 air is of fairly uniform intensity but it is natural ly of somewhat more concentrated character im mediately in front of the leading face I 000i each impeller blade. By reason of the angular advance of each impeller blade with respect to its corre 60 sponding propeller blade, the concentrated streams of abrasive on the leading faces of the with blades B, it should be observed that as the abrasive travels outwardly over surfaces 59 of each blade, it is prevented from laterally escap ing from the free edge of the blade by ?ange ' 63, and it is prevented from abrading runner, head 48 or guide plates 53 by ?ange G2, which keeps the abrasive, spaced a considerable distance from these parts‘;v The abrasive is therefore supplied to the inner 40 ends of blades B in a predetermined limited an gular region, and as it travels outwardly, each particle de?nes a spiral path and is directed against the work over a definite region. There fore, none of the abrasive, properly discharged 45 from the opening I00, strikes any of the sta tionary parts of the device. However, a minute amount of “stray” abrasive is sometimes admit ted to the blades in a region other than that ad ,jacent discharge slot I00, and this abrasive, as it 50 is discharged from blades B (Figure 2), strikes‘ either guard plate II, II, IE or 23. As the amount of this stray abrasive is comparatively small, the wear plates accordingly have a long life before they must be renewed. When it does, 55 however, become necessary to renew any of the housing guards or rebound guards they may be mainly replaced by detaching their securing S- . Moreover, because of the large space provided 60 between the tips of blades B and the upper part of the cabinet, particularly the corners of hous impeller blades are thrown outwardly through ing H, the abrasive is given a chance to expand I slot I00 in such manner, and at such a time and is not confined adjacent the rotor. There fore wear of the rotor and the wear plates is mini that the inner curved end SI of blade B will 65 properly pick them up with a minimum of im pact and “splash”. As the abrasive is exhausted through slot I00, it possesses angular as well as radial velocity in view of the impelling action of blades IN. This feature, when taken in con 70 nection with the fact that the inner ends of blades B are curved, operates to minimize any abrading action that may take place as blades mized. Rebound guard 35 is provided in order 65 to prevent stray abrasive from being discharged upwardly and striking guard plate 23 and then rebounding back into contact with and abrading runner head 48, which, as previously mentioned, 70 is a permanent part of the machine. Lower rebound plate 3‘! is provided to prevent abrasive from rebounding from the work and striking run B initially pickup the abrasive. The abrasive _ner head 40. If it is desired to inspect the runner accordingly travels outwardly and angularly, blades or other parts of the device located in 75 76 2,108,005 the upper portion of housing H, nuts 28 ‘may be ' 5 loosened and lid l6 lifted to expose the interior unequal number of impeller and ‘propeller blades may be used without sacri?cing the advantages of the cabinet. of those features. ‘ _ ._ .1 _ .. .7- .l r When it becomes necessary to replace blades B . Although Ihave illustrated cage Gas-being it is merely necessary to loosen nuts ‘I2, remove ' adjustably mounted upon spout holder 8|, and I - nuts 99, so as to detach cage C, from the holder, prefer to employ this arrangement as it makes and pull the entire feeding assembly (with the it possible to maintain the spout in a ?xed posi exception of cage C) axially to the right, and tion irrespective of the adjusted position of the remove it from the machine. It is then possible cage, it is to be understood that if desired these to reach into the comparatively large opening parts may be permanently connected or'integral ‘and remove the single cap screw I86 which holds‘ ly formed, and arcuately-shaped slots provided, the impeller in place and remove the impeller in holder 8| or arm 68 ‘in the region where bolt and cage C as a unit from the machine. After and nut assemblies 19 cooperate with them, so the impeller and cage have been removed from as to mount the holder as well as the cage for the machine they may be disassembled by align angular adjustment upon arm 68. 15 ing impeller blades ml with notches 89 of Although I have illustrated an impeller assem ?ange 9|. \ bly that is disposed in a predetermined ?xed posi After cage C’ and the impeller have been re tion by machine screws 41, and I prefer to use moved in the manner just described, blades B this construction, because I have experimented 20 maythen be individuallyslid inwardly to the large central space and then withdrawn and replaced by new blades. At this time, wear plate 46 may also be renewed, if necessary, by removing ma chine screws 41. After the new blades are in 25 place and plate 46 is secured to shaft 38, the impeller (or a new one if it requires replacement) 30 86 40 .45 50 is then put in place with cage C and the impeller and aligned with screws 41 as previously de scribed. Although as illustrated I preferably em ploy a wear plate 46 which is separately formed from the impeller because these parts wear at different rates of speed, they may if desired be made integral without departing from the spirit of the present invention. In the event that plate 46 and the impeller are integrally formed, screws 41 are dispensed with and dowel pins or the like employed to cooperate with openings in member 45 for properly positioning the impeller in-the device, and also notches 89 will be formed in ?ange 88 instead of ?ange 9|, in order to facili tate assembly of the impeller with the parts. Moreover, in the two part construction shown, notches 89 may be provided in ?ange 88 instead of ?ange BI, and in such case the entire feeding assembly, including cage C may be removed by merely loosening nuts 12 and aligning the im peller with notches 89. After the parts just described have been put in place, the remaining parts of the feed assembly may be slid to the left toward the opening in the machine. The cage is then secured to the holder by nuts 99 and the holder assembly is slid over studs 69 until it is arrested by contact of posi tioning screws 14 with the'studs. 55 Nuts 12 are then tightened and the machine is ready for operation. In this connection it should be ob served that the horizontal contacting bearing faces provided on bracket 61 and base III are of considerable area, which forms an adequate sup 60 port for the feed assembly. Although I have illustrated and prefer to em ploy a runner assembly'embodying four impeller blades and four propeller blades, it is to be under stood that if desired the number of blades in 65 each set may be one or more blades, depending upon the'size of the wheel and the abrading characteristics desired. In any event, however, an equal number of ‘blades is employed in each set, in order that the impeller may discharge 70 the abrasive through slot Hill a predetermined angular degree in advance of the inner ends of the propeller blades and bring about the bene ?cial results previously discussed. It is to be understood, however, that insofar as the other 75 novel features of my machine are concerned, an and determined the proper angle of advance of 20 the impeller blades with respect to the propeller blades, and which remains ?xed throughout the life of the machine, it is to be understood that if it is‘desired to operate the machine in a manner that requires it, slots I85 in impeller ?ange I84 may be elongated so as'to provide a predeter mined range ofadiustability of the impeller with respect to the runner, and the appended claims are. intended to embrace my machine when it assumes this form. Moreover, I prefer to use the 30 positioning means shown as it is of simple form and does not entail the use of additional parts, but I may if desired, especially if an adjustable impeller is used, employ a dowel pin on one of the parts which may be selectively engaged with 35 one, or with one of a plurality of holes located in another of the parts for positively or selective ly adjusting the impeller respectively, without departing from the spirit of the present invention. In Figure cage C’ for ures 1 to 5, an abrasive 6 I have shown a modi?ed form of 40 use in the machine shown in Fig inclusive. Cage C’ is provided with discharge slot “10a, having a pref erably plane wall H0, which is substantially tangentially disposed with respect to the path of the tips of blades IN, and a preferably plane inclined wall Ill. ' This cage assembly has been found to have an extremely long life by reason of the abrasive striking the parts in such ‘manner as to avoid 50 recurrent rebounding of the abrasive on the inner surface of cylindrical portion 81a of cage 0', thereby avoiding the wearing of pits or other surface irregularities in the cage. Assuming that the machine is operating at the proper speed 55 and that abrasive is fed into the cage in the man ner described in connection with the ?rst form of my invention, the abrasive is churned around in the cage and when each blade reaches open ing I 00a it discharges a predetermined quantity of abrasive therethrough and onto the inner end of its corresponding propeller blade. A small quantity of abrasive however fails to be dis charged through opening lll?a and strikes wall 65 III of opening “18a, and this abrasive, by reason of the inclination of wall III, is ‘smoothly guided back into cage C’ and is carried around therein, without rebounding against wall 81a, until it is brought around into the proper position to be 70 discharged through opening l?iia. With this structure I have found that the cage, when it has worn sufficiently to require replacement, is uniformly worn throughout the extent of the inner surface of its cylindrical portion 81a of the 6 2,108,005 cage without the formation of pits or‘ other sur face irregularities. . The terms “runner” and “rotor" employed in the appended claims are intended to embrace the blade carrying member irrespective of whether it is made in one piece or is as a matter of fact integrally formed with shaft 38, or is made up of two members 45 and 48 and secured to shaft 38 vs shown in the drawings. Moreover, I prefer 10 to support the propelling blades at one edge only, but it is to be understood that the invention embraces runner assemblies having an apertured side plate secured to the other edges of the blades or other similar constructions. The invention may be embodied in other spe 15 ci?c forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the 20 scope of the invention being indicated by the ap radial direction and discharge it from the outer ends of said blades at an abrading velocity when said rotor is rotated, a rotatable impeller com prising a plurality of impeller vanes disposed within said feeding device, said vanes extending to a region closely adjacent the axis to de?ne a comparatiyely small axially extending passage, the forward face of each impeller vane being concave in transverse section, and means for introducing abrasive into said passage and over 10 the inner edges of said vanes, said vanes being operable to impel a contracted stream of abrasive through said discharge opening. - 3. In an abrading machine, a rotor having a plurality of blades terminating short of the axis 15 of said rotor to de?ne an abrasive admitting space, an abrasive feeding device of an external diameter less than the radius of the rotor ex tending into said space and having a discharge opening therein disposed to one side of the axis pended claims rather than by the foregoing de of said rotor and located between the planes of scription, and all changes which come within the ‘rotation de?ned by the sides of said blades for meaning and range of equivalency of the claims delivering abrasive to the inner ends of said are therefore intended to be embraced therein. blades, said blades terminating su?iciently close 25 What is claimed and desired to be secured by to said feeding device to pick up the abrasive 'United States Letters Patent is: with a minimum impact and being operable to 1. In an abrading machine, a rotor having a discharge it from the outer-ends of said blades plurality of blades terminating short of the axis at an abrading velocity when said rotor is rotated, of said rotor to de?ne an abrasive admitting a rotatable impeller comprising a plurality of space, an abrasive feeding device of an external impeller vanes disposed within said feeding de 80 diameter less than the radius of the rotor ex vice, said vanes being joined adjacent said rotor tending into said space and having a discharge by a generally circular ?ange, said vanes extend opening therein disposed to one side of the axis ing to a region closely adjacent the axis to of said rotor and located between the planes of de?ne a comparatively small axially extending rotation de?ned by the sides of said blades for passage, and means for introducing abrasive into delivering abrasive to the inner ends of said said passage and over the inner edges of said blades, said blades terminating sumciently close vanes, said vanes being operable to impel abra to said feeding device to pick up the abrasive with sive through said discharge opening, said feeding a minimum impact and said blades having sub device having an inwardly extending abrasive retaining ?ange disposed between said generally 10 stantially smooth and uninterrupted abrasive ' propelling surfaces of sui?cient length to accel erate the abrasive smoothly and continuously and without abrupt changes in a“ substantially radial direction and discharge it from the outer ends of said blades at an abrading velocity when said rotor is rotated, a rotatable impeller mounted for synchronous rotation with said rotor and com prising a plurality of impeller va'nes disposed within said feeding device, said' vanes being equal 50 in number to said blades and extending to a region closely adjacent the axis to de?ne a com paratively small axially extending passage, and means for introducing abrasive into said passage circular ?ange and said rotor and having an internal diameter which is less than the external diameter of the latter‘?ange, whereby they are radially overlapped to minimize abrasive leakage. 4. In an abrading machine, a housing, a rotor mounted for rotation in said housing and having a plurality of blades thereon, said blades ter minating short of the axis of rotation of said ‘ rotor to de?ne a central abrasive admitting space, an abrasive feeding device having an ex ternal diameter less than the radius of the rotor disposed in said space and having a discharge opening therein disposed toone side of the axis and over the inner edges of said vanes, said vanes , of said rotor and located wholly between the - being operable to impel predetermined quantities of abrasive through said discharge opening and into the path of the inner ends of said blades in timed relationship thereto. 2. In an abrading machine, a rotor having a‘ 60 plurality of blades terminating short of the axis ‘of said rotor to de?ne an abrasive admitting space, an abrasive feeding device of an external diameter less than the radius of the rotor extend ing into said space and having a discharge open ing therein disposed to one side of the axis of said rotor and located between the planes of rota _ tion de?ned by the sides of said blades for deliv ering abrasive to the inner ends of said blades,‘ planes of rotation de?ned by the sides of ‘said blades for delivering abrasive to the inner ends of said blades, said feeding device being located wholly within said housing and having an axial length which is only slightly greater than the width of said blades, said blades being operable to pick up said abrasive and discharge it from the outer ends of said blades at an abrading velocity'when said rotor is rotated at a predeter min'ed speed, a stationarily supported conduit extending into said housing for delivering abra sive to said feeding device, said conduit and feed ing device having a joint located wholly within said housing for placing them in ?uid communi said blades terminating sufficiently close to said 70 feeding device to pick up the abrasive with a minimum impact and said blades having sub feeding device for impelling abrasive through said discharge opening. stantially smooth and uninterrupted abrasive propelling. surfaces of su?icient length to accel erate the abrasive smoothly and continuously and without abrupt changes in a substantially mounted for rotation in said housing and having a plurality of blades terminating short of the axis of rotation of said rotorto define a central 15,, cation‘, and a rotatable means disposed in said 5. In an abrading machine, a housing, a rotor 70 2,108,006 7 tending into said space and having a discharge opening therein disposed to one side of the axis of said rotor and located between the planes of having a discharge opening therein disposed to rotation defined by the sides of said blades for one side of the axis of said rotor and located delivering abrasive to the inner ends of said wholly between the planes of rotation de?ned by blades, said blades terminating su?iciently close the sides of said blades for delivering abrasive to said feeding device to pick up the abrasive to the inner ends of said blades, said feeding with a minimum impact and arranged to dis device being located wholly within said housing charge it from the outer ends of said blades at 10 10 and having an axial length which is only slightly an abrading velocity when said rotor is rotated, greater than the width of said blades, said a rotatable impeller mounted for synchronous blades being operable to pick up said abrasive rotation with said rotor and comprising a plu and discharge it from the outer ends of said rality of impeller vanes disposed within said blades at an abrading velocity when said rotor feeding device, said vanes being equal in number to said blades and being so angularly positioned 15 is rotated at a predetermined speed, a station arily supported conduit extending into said with respect thereto as to impel abrasive through housing for delivering abrasive to said feeding said discharge opening onto the inner ends or device, said conduit and feeding device having a said blades in a predetermined timed relation ship thereto, a single centrally disposed fasten joint located wholly within said housing for plac 20 ing them in ?uid communication, and a rotatable ing device extending through said impeller and 20 secured to said rotor for ?rmly holding the said means disposed in said feeding device for im pelling abrasive through said discharge opening, impeller to the latter, and means for preventing said joint comprising means for securing said said impeller from being assembled in said rotor in any position other than its proper angular feeding device and said conduit together in an gularly arUustable relationship, whereby said position, comprising a projection provided on‘ said rotor and extending into a recess provided feeding device is supported upon said conduit. 6. In an abrading machine, a rotor having a in said impeller remote from said impeller secur plurality of blades terminating short of the ing means, and means for introducing abrasive axis 0! said rotor to de?ne an abrasive admitting into said feeding device. abrasive admitting space, an abrasive feeding device having an external diameter less than the radius of the rotor disposed in said space and 30 30 space, an abrasive feeding device of an external diameter less than the radius oi the rotor ex WALTER L. KEEFER.