US2933861A

US2933861A - Continuous feed tumbling apparatus

Info

Publication number: US2933861A
Application number: US734024A
Authority: US
Inventors: Robert R Bintzler
Original assignee: Ransohoff Inc
Current assignee: Ransohoff Inc
Priority date: 1958-05-08
Filing date: 1958-05-08
Publication date: 1960-04-26
Anticipated expiration: 1977-04-26

Description

April 26, 1960 R. R. BINTZLER CONTINUOUS FEED TUMBLING APPARATUS 3 Sheets-Sheet `1 Filed May 8, 1958 FAU! April 26, 1960 R. R. BINTZLER CONTINUOUS FEED TUMBLING APPARATUS 3 Sheets-Sheet 2 Filed May 8. 1958 ATTORNEYS.

April 26, 1960 R. R. BINTZLER coNTINuous FEED TUMBLING APPARATUS 5 Sheets-Sheet 3 Filed May 8. 1958 IN VENTOR.

nited States Patent@ CONTINUOUS FEED TUMBLING APPARATUS Robert R. Bintzler, Cincinnati, Ohio, assignor, by mesne assignments, to Ransoholf Company, Hamilton, Ohio, a corporation of Ohio Application May 8, 1958, Serial No. 734,024

9 Claims. (Cl. 51-164) This invention relates to industrial treating machines in'which metal workpieces are subjected to a surface treatment, such as cleaning, polishing or de-burring, by agitation in the presence of a mass of treating material.

In general, a typical tumbling mill comprises a cylindrical tumbling barrel or drum mounted for rotation about a horizontal axis and arranged to confine the mass of treating material and workpieces, such as metal parts. During rotation of the drum, the parts and treating material are agitated together as a commingled mass, causing the treating material to effect a scrubbing actionV with respect to the various surfaces of-the metal parts. A machine of this genera-1 character is disclosedl in the patent to Nathan Ransohoff, No.` 2,999,832, issued on October 13, 1942. The machine of the prior patent is of the intermittent or batch treatment type, that is, a mass of loose treating material and a batch of metal parts are tumbled in the drum for a predetermined period of time, then the batch of parts is discharged from the machine in iinished condition. In order to bring about the batch operation, the machine is reversible, being arranged to retain the parts in the tumbling barrel during rotation in a tumbling direction and to discharge them only during rotation in a reverse or discharge direction. During discharge rotation,'the treating material is separated from the discharging parts to be returned to the tumbling barrel for treating a subsequent batch of parts.

It has been one of the primary objectives of the present invention to provide a tumbling machine for the con-- tinuous advancement of the work through aV tumbling chamber for treatment, and through a separator for dis' charge as a continuous stream in finished condition, while the mass of loose treating material concurrently is screened from the discharging parts and recirculated back to the tumbling chamber for reuse. In other words, the

present apparatus is arranged to provide a continuous unidirectional ow of work parts through the machine, accompanied with continuous screening and recycling of the treating material in a closed circuit, as distinguishedl from the prior batch-type operation.

The present apparatus is intended for subjecting metal parts to several diiferent kinds of treatment, depending upon the nature of the work. For example, certain classes of work, such as castings or machined parts, may require an abrasive treatment in which burs or roughness are removed by abrasive action from the work surface; other classes of work may require a cleaning or polishing treatment. In tumbling work requiring an abrasive action, such as de-burring, the machine is charged with an appropriatehard abrading material, which may consist of metal slugs, stars, or fragments of stone. On the other hand, where a cleaning or polishing action is required, the machine may be charged with a non-abrasive material, such as wood, saw dust, or similar material suited to the type of work being treated.

In treating the parts with heavy abrasives, the abrasive particles are readily separated from the workpieces and recirculated through the machine; however, saw dust and amasar Patented Apr. 26, 1960 ice similar light-Weight materials are more difficult to handle.

By way of example, when the parts are charged into the machine in wet condition for polishing or cleansing with saw dust, the moisture is absorbed by the saw dust; consequently, the moist particles have a tendency to adhere to one another and to form lumps or cakes. The moist particles also adhere to the machine surfaces and to the treated parts so as to interfere with the screening process.

It is therefore another objective of the invention to provide a tumbling apparatus arranged to advance the metal parts and treating material, particularly saw dust or the like, in a positive manner through the apparatus, combined with a separator arranged to eiciently separate al1 of the treating material from the workpieces as they ow toward the discharge end of the apparatus.

A further objective has been .to provide an apparatus in which the separator structure has the double function of screening the saw dust from the polished parts, and also of driving absorbed moisture from the saw dust in a rapid efficient manner by heating the material during recycling, thereby to improve the overall eiciency of the machine.

Briefly, an apparatus constructed according to the present invention comprises a barrel or drum having a tumbling compartment at one end, in which the tumbling operation is carried out, and a separating section in which the treating material is separated from the treated parts, collected and recirculated back to the tumbling compartment. The separating section comprises a cylindrical screen or perforated cylinder having a diameter substantially smaller than the tumbling chamber and surrounded by a cone-shaped collector chamber providing a surface which slopes downwardly toward the end of thev conveying the metal parts and treating material longitudi' nally through the machine.

- In order to elevate the treated workpieces from' the.

periphery of the tumbling chamber to the separator cylinder, which is substantially smaller in diameter, a generally convolute discharge scoop extends from the trailing end of the helix and communicates with the end of the separator cylinder. During rotation of the unit, the scoop, upon-each revolution, elevates a quantity of the treated parts and the material from the tumbling chamber to the separator cylinder. A return scoop communicates with the lower end of the cone-shaped collector chamber, and in a similar manner, periodically elevates the screened material from the collector to a conical return tube which advances the treating material back to the charging end of the tumbling chamber for reuse. These components advance the parts and material in a substantially positive manner through the apparatus as a consequence of its rotation.

During rotation, the parts to be treated are introduced continuously into the charging end of the tumbling chamber to be agitated and advanced with the mass of treating material-which is maintained at a predetermined level within the chamber; the parts, together with the surroundi ing material are then elevated to the separator cylinder for advancement of the parts in the same direction to the discharge end of the separator cylinder while the separated treating material is separated and recycled in the opposite direction back to the charging end of the turn-v ber is heated by an external heat source to artemperature suiciently high to dehydrate the moist saw dust. The particles of moist saw dust screened from the parts .thus drop from the separator cylinder into contact with the heated, sloping surface of the .collector chamber. It has been found that the particles readily flow down the heated surface by reason of its combined slope and rotary motion, the material being thoroughly dried before it is elevated by the return scoop and conveyed by the conical return tube back to the charging end of the tumbling chamber. The parts advancing through the separator cylinder are also exposed to the heat within the collector chamber to aid in drying and dislodging the adhering particles. hydration of the saw dust and positive feeding action provided by the apparatus, the surfaces of the entire machine are kept free of adhering saw dust, while the treated parts are discharged with the saw dust completely separated from them.

The various features and advantages of the invention will be more clearly apparent to those skilled in the art from the following description taken in conjunction with the drawings.

-ln the drawings: f

Figure l is a side elevation of a tumbling mill embodying the invention, the machine being partially broken away to show the arrangement of certain internal parts.

Figure 2 is a longitudinal sectional view of the machine.

Figure 3 vis a cross sectional view taken along line 3-3 of Figure '2, illustrating the arrangement of the discharge scoop which leads from the tumbling chamber to the screening cylinder.

Figure r4 is a sectional view taken along line 4.4 of Figure 2, illustrating the return scoop 'leading from the collector chamber for recirculating the screened treating material back to the tumbling chamber.

Figure 5 is an exploded view looking toward the discharge end of the machine, further illustrating the relationship of the collector chamber, separator cylinder and return scoop.

Figure 6 is an exploded view looking toward the charging end of the machine, further illustrating the relationship of the tumbling chamber and discharge scoop.

Figure 7 isa 'ow diagram'illustrating the direction of advancement of the workpieces and related circuit of loose treating material-during operation ofthe machine.

General arrangement The structure selected to illustrate the principles of this invention, as shown generally in Figure 1, comprises a tumbling barrel or drum, indicated generally at 1, which is rotated as a unit about a horizontal axis ata relatively slow speed to provide the tumbling action.V The workpieces to be treated are fed into -the charging end 2, then the pieces advance longitudinallyv through the machine and flow from the discharge end 3 in linished condition. In the example illustrated, the parts are introduced into the charging end by way of a stationary charging chute .4; the finished parts, which ow vfrom the discharge end, are carried olf by a discharge c hute 5.

The tumbling barrel 1 preferablyvis of welded construction and its opposite ends are supported for rota'- tion above a frame-work 6 lfabricatedfrolfn structural iron. The opposite end portions of the tumbling barrel 1 are provided with tracking rings 7 and 8, riding upon respective sets of flanged rollers lll-f1() and 114-11 which are journalled in bearing brackets 12 carried by the Vframe-work 6. The trackingrings 7 andivS preferably are welded to the external surface of thetumbling barrel; the respective lrollers of each set are spacedapart transversely to stabilize the tumbling barrel with respect to the frame-work 6.

The tumbling barrelis rotated by amotor d'13 mounted By virtue of the thorough de- Y `upon a support frame 14 rising from the frame-workp. The motor 13 preferably is of the gear head type, having a gear reduction unit 1S to provide the desired speed of barrel rotation. The motor drive comprises a motor sprocket 16 meshing with a sprocket chain 17 passing around a large sprocket 18, which is wel-ded to the turnbling'barrel adjacent the tracking ring 7. The motor driving system rotates the barrel as a unit in the direction indicated by the arrow during operation of the machine.

Described generally with reference to Figure 2, the tumbling barrel 1 comprises a tumbling chamber 2t), an intermediate baie or partition 21, a separator cylinder 22 projecting end-wisely from the tumbling chamber, and a cone-shaped collector chamber 23 surrounding the separator cylinder. These components are all joined together in coaxial relationship for rotation as a unit. In order to utilize the collector chamber as a saw dust dehydrator, an elongated heating element 24, preferably comprising a lineal gas burner, is mounted beneath the collector chamber and arranged to project blast dames upon the external surface of the chamber. The burner is supported -by one or more brackets 25 and includes a suitable control valve and mixing chamber 26 of conventional design for regulating the dehydration temperature. When the parts are treated with non-absorbent material, such as Vhard abrasives which do not require drying, the burner is shutdown during operation of the machine.

T umbling section the opening contines the mass of treating material at ay predetermined level as indicated at 30. The barrel is provided with a conveyor vane or helix 31 which spirals from the end wall 27 to a discharge scoop, indicated generally at 32, mounted upon the intermediate wall 2l. The spiral vane comprises metal plates welded as at 33 to the internal surface ofthe tumbling chamber; the lead of the vane, during rotation of the tumbling barrel in the direction indicated, provides advancement of the parts from the forward wall 27 to the scoop 3 2, which elevates and transfers the parts and treating lmaterial to the separator cylinder 22.

As described later in detail, the treating material vis returned continuously to the charging end of the tumbling chamber by a lconical return tube indicated generally `at 34. T Ihe internal surface of the return tube slopes downwardly .toward the charging end of the machine, such that the material vflows from the end -of the cone tothe space 35 delineated by theleading end of the Aspiral vane and theend wall 27. Itwill be noted that-itheend of the charging chute 4 also `communicates with the `chargingspace V35, such that a continuousstream of treating material and a continuous supply of metal parts concurrently are fed by the cone and chute to the chargingend of therotating vbarrel for advancement longitudinally by the helix.

As the parts and treatingmaterial approach the intermediate -wall 21, they are advanced Ain a positive manner bythespiral vane into the discharge yscoop 32., As best shown in Figure 3, scoop 32 is of a;convolut,e shape, providing lanenclosed ramp having-a receiving end cornmunicating with the vtrailing end `of the yspiral ,vane as at36. `The delivery end of the scoop leads Vto an opening 37 in theintermediate wall (Figures 2 and `5) which communicates with. the end of the l separator cylinder 22.

In the exampleillustrated, thefscoop comprises.V spaced -sidewwalls 3%?38 welded .as at :4G tothe intermediate wall 21, the outer ends oftheside vwalls'being joined-by a -top wall y41. The -top wall preferably is inclined as spesse;

the separator screen.` Upon each rotation of the turnbling barrel, as indicated in Figure 3, the quantity of parts and material at the trailing endof the vane passes into the receiving end of the scoop; during continued rotation from the position shown, the parts and material are skidded along the curved surface of the scoop, elevated to the opening 37, andnally delivered in to the end of the separator cylinder 22.

Separating section In the example illustrated, the separator cylinder 22 is fabricated from sheet metal, which is perforated as at 43 to allow the treating material to pass to the coneshaped collector chamber 23 as it is separated fromA the metal parts. The perforations preferably extend for the full length of the collector chamber and terminate as at 44 (Figure 2) adjacent the end Wall 45 of the collector chamber. The respective opposite ends of the separator cylinder are welded as at'46 to the intermediate wall 21 and end wall 45.

In order to advance the parts and treating material,

,the separator cylinder includes a spiral vane 47, similar t0 the vane 31, of the tumbling chamber and leading in the same direction. The parts and material are thus advanced continuously from the intermediate Wall toward the discharge end 3 of the machine during rotation of the tumbling barrel. The treating material is progressively screened from the parts during advancement along the separator cylinder and drops by gravity to the sloping surface of the collector chamber 23. By reason ofthe rotation of the chamber and its sloping surface, the sep# arated material gravitates toward the intermediate wall 21, where it is picked up by the return scoop indicated at 48.

As best shown in Figure 4, return scoop `4S is generally similar to the discharge scoop 32, having a receiving end 50 residing adjacent the periphery of chamber 22, and having a delivery end 51 communicating with the conical return tube 34. It will be noted in Figure 4, that the scoop 48 is welded directly to the ,intermediate wall 21 and that its upper delivery end 51 passes through an opening 52 of the separator cylinder 22 for direct communication with the return tube 34. During each rotation of the barrel, the receiving end 51 of the scoop passes through the mass of material accumulated adjacent the intermediate wall; during continued rotation, the scoop elevates the material and finally delivers it to the return tube 34 for advancement to the receiving end of the barrel, as previously indicated at 35.

As shown in Figure 2, the adjacent ends of the sep` arator cylinder 22 and return tube 34 are telescopically intertted, the end of tube Y34 being closed oi by a wall 53 to prevent intermingling of the workpieces and treating material. The related diameters of the two tubes delineate an annular space 54 (Figure 4) providing clearance for the parts passing from the discharge scoop 32 into the separator cylinder. The rearward end of the return tube 34, which passes into the separator cylinder, is supported by the intermediate wall 21, the tube being welded as atv 55 to the wall opening through which it passes'. The forward end of the return tube 34 is supported by a spider 56 having radial armsV secured as at 57 to the periphery of the tumbling chamber.

Operation When the machine is set up for treating a given type of work, a suitable quantity of saw dust or other treating f material is introduced into the tumbling chamber to p rovide an operating level, previously indicated at 39. The stream of parts as indicated in Figure 2, is charged into the chamber by way of the chute 4 either manually or by conveyor equipment. The ow of parts and treating material through the tumbling chamber is indicatedby the arrow A in Figure 7, while the corresponding ow of treating: material is indicated bythe arrow B in broken lines. Atthe trailingend of the spiral vane, treated parts and treating material are elevated to the separator cylinder 22 as shown by the vertical arrows VA1 and B1 (discharge scoop 32). This action is illustrated in Figure 3 in which the quantity of parts and material are indicated at 58.

During advancement along the separator cylinder 22, the screened particles of treating material drop by gravity as indicated, flow downwardly along the sloping surface of the cone-shaped collector chamber 23 as indicated by the arrow B2; the screened material then is elevated to the return tube 34 (return scoop 48) as indicated by the arrow B3. This action is shown in Figure 4, in which the screened material (or dehydrated saw clust)l is indicated at 60. Thereafter, the material gravitates longitudinally along the return tube as indicated by the arrow B4 in its recycling circuit back to the charging end of the tumbling chamber, while the finished parts advance in the opposite direction to the discharge end, as indicated by the arrow A2. v

When saw dust is used in treating the workpieces, the gas burner 24 is placed in operation and the moist saw dust is dehydrated as it gravitates along the collector chamber, as indicated by the arrow B2. As noted earlier, the heat which is confined in the collector drum, also acts upon the parts which are advancing along the separator cylinder 2.2., Any moist sawdust particles which may adhere to the parts or to the separator'cylinder are dehydrated, at least partially, and dislodged during longitudinal motion of the parts along the separator;l consequently, there is no opportunity for moist particles to build up and clog the apertures of the separator during continued operation. It has been found that the combined separating and dehydration action also prevents the saw dust from adhering to the collector chamber with attendant scorching or overheating of the material. Since the dehydrated saw dust retains a certain amount of the absorbed heat upon being returned to the tumbling chamber, the cleaning and drying action is accelerated and the efficiency of the machine is therefore improved.

It will be noted that the discharge scoop 32 and return out any structural changes, other than to equip the apparatus with a reversible motor 13 for driving the machine in a direction opposite to that indicated. Since the scoops are ineffective during reverse rotation, the parts and material maybe agitated for a predetermined time period in the tumbling chamber.V Thereafter, the motor is reversed after a treatment period, causing normal operation to be resumed.

Having described my invention, I claim:

l. A treating apparatus for tumbling a stream of workpieces with loose recycled treating material comprising,l a tumbling drummounted for rotation about a generallyV horizontal axis and having a charging end, separator means projecting outwardly from the opposite-end of said drum along said axis, discharge means interconnecting the tumbling drum and separator means for transferring workpieces and treating material from the', tumbling drum to the separator meansduring rotation thereof, said separator means having a discharge opening and having means for screening the treating material from the workpieces while advancing the workpieces to# ward said discharge opening, a return device adapted to advance the screened treating material toward the charg ing end-of the tumbling drum, and return means inter` connecting the separator means and return device for transferring the screened treating` material to the return bling drum, tumbled, then transferred to said separator means and discharged therefrom while the treating inaterialis screened and recycled in a closed circuit between the ,tumbling drum ,and separator means.

2l A treating apparatus for tumbling a stream of workpieces with loose recycled treating material, comprising a `tumbling drum mounted for rotation abouta generally horizontal axis and having'a charging end, separator means projecting outwardly from the opposite end of said drum along saidaxis, discharge means interconnecting the tumbling drum and separator means for transferring workpieces and treating material from the turnbling drum to the separator means during rotation thereof, said separator means having a discharge opening and having means for screening the treating material from the workpieces while advancing the workpieces toward said discharge opening, a return tube mounted within the tumbling drum along said axis, said tube having ,a discharge end adjacent the charging end of the tumbling drum, and return means interconnecting theseparator means and return tube for transferring the screened 'treating material to the return tube during rotation thereof, whereby workpieces are fed into the charging end of the tumbling drum, tumbled in the presence of the treating material and discharged while the treating material is screened, transferred to the return tube and recycled to the charging end of the tumbling drum in a closed circuit.

3. A treating apparatus `for tumbling a stream of workpieces with loose recycled treating material comprising, a tumbling drum mounted for rotation about a generally horizontal axis and having a charging end, a separator projecting outwardly from said drum along said axis, discharge means interconnecting the tumbling drum and separator for transferring workpieces and treating material from the tumbling drum to the separator during rotation thereof, said separator having a discharge end and having means for screening the treating material from the workpieces while advancing the workpieces toward said discharge end, a collector chamber surrounding the separator for collecting the screened treating material, a heating element associated with the collector chamber for heating the same to a dehydration temperature, a return device adapted to advance treating material toward the charging end of the tumbling drum, and return means interconnecting the collector chamber andY return device for transferring the screened treating material to the return device for advancement toward the charging end of the tumbling drum during rotation thereof, whereby workpieces are fed into the charging end of the tumbling drum, tumbled in the presence of the treating material and discharged while the treating material is screened therefrom, dehydrated in said coll lector chamber and recycled to the charging end of the tumbling drum.

4. A treating apparatus for tumbling a stream of workpieces with loose recycled treating material comprising, a tumbling drum mounted for rotation about a generally horizontal axis and'having a charging end, a separator projecting outwardly from said drum, discharge means interconnecting Ythe tumbling drum and separator for transferring workpieces and treating material from the tumbling drum to the separator during rotation thereof, s aid separator having a discharge end and having means for 4screening the treating material from the workpieces while advancing the workpieces toward said discharge end, a collector chamber surrounding the separator for collecting the screened treating material, a return tube mounted within the tumbling drum and having a discharge opening adjacent the charging end of the tumbling drum, a "heating element associated withthe collector chamber for heating the/same to adehydration temperature, and return means interconnecting the collector chamber and return. tube for .transferring the lscreened treating material .to the return tube during rotation thereof, whereby workpieces are fred into the charging end vof the' tumbling drum, tumbled in the lpresence of the treating material and discharge, while the treating material is screened therefrom, dehydrated in .said .eollector chamber and recycled to the charging end of the tumbling drum. v Y

i5. A treating apparatusfor tumbling a stream of workpieces with loose recycled treating material comprising, a tumbling drum mounted for yrotation about a generally horizontal axis and having a charging end, separator means projecting outwardly from the opposite end of said drinn along said axis, discharge means interconnecting the tumbling drum and separator means for transferring workpieces and treating material from the tumbling druni to the separator means during rotation thereof, said separator means having a discharge opening and having means for screening the treating material from the workpieces while advancing the workpieces toward said discharge opening, a collector chamber extending along said axis and surrounding the separator means for 4collectingthe screened treating material and having an internal Asurface sloping downwardly toward the end of the tumbling drum, a return tube mounted within the tumbling drum along said axis, said tube having a discharge opening adjacent the charging end of the tumbling drum and having an internal surface sloping downwardly Ytoward Vthe said discharge opening, and return means interconnecting the collector chamber and return tube for transferring `the screened treating material to the return tube during rotation thereof, whereby workpieces are fed into the charging end of the tumbling drum, tumbled in the presence of the treating material and discharged, while the treating material is screened therefrom and recycled to the charging end of the tumbling drum.

Y 6. Aitreating apparatus for tumbling a stream of workpieces in the presence of loose, recycled treating material comprising, a tumbling drum mounted for rotation about a substantially horizontal axis, said drum having a charging end for receiving the stream of workpieces and having an internal helix arranged to ladvance the workpieces longitudinally during rotation of said drum, screening means extending outwardly from said drum substantially along said axis and having a discharge end, discharge means for transferring workpieces and treating material from the tumbling chamber to the screening means during rotation of said drum, vsaid screening means having an internal helix for advancing the workpieces toward said discharge end and separating the treating material therefrom during rotation of the screening means, collector means surrounding the screening means and collecting said separated treating material, and return means transferring the separated material from the collector means, said return means adapted to advance the separated material toward the charging end of the tumbling chamber during rotation of the drum, whereby a continuous stream of workpieces is fed into the charging end of the tumbling chamber, tumbled in the presence of the treating material and discharged while the treating material is recycled vfrom the collector chamber back to the tumbling chamber.

7. A treating apparatusfor tumbling a stream of workpieces with looserecycled treating material comprising, a tumbling drum mounted for rotation about a generally horizontal axis and havinga charging end, said drum having a partition delineating the opposite end thereof, an

i internal helix disposedrwithin the tumbling drumfor advancing workpieces and treating material from said charging end toward said partition during rotation of the vtumbling drum, a discharge scoop mounten1 adjacent said partition and having a'receiving end kdisposed adjacent the internalsurface of the'tumbling drum, said internal helix having ,a trailing end communicating with said receiving end for `advancing the workpieces and treating-material thereto, a screening cylinder extendingoutwardlyfrom said partition along said axis, said discharge scoop having a delivery end communicating with said screening cylinder for delivering the treating material and workpieces thereto during rotation of the apparatus, said screening cylinder advancing the workpieces while screening the treating material thererom, a collector chamber surrounding the screening cylinder for collecting the screened treating material, a return tube extending from said partition toward the charging end of the tumbling drum along saidaxis, said tube having a discharge end adjacent the charging end of the tumbling drum, and a return scoop interconnecting the collector chamber and return tube for transferring the screened material to said return tube, said return tube conveying the screened treating material to the charging end of the tumbling drumduring rotation thereof to be recycled with a stream of parts fed into the charging end of the tumbling drum. e

8. In a rotatable tumbling machine for treating a continuous stream of workpieces in the presence of loose .treating material, said tumbling machine having a charging end, an apparatus for separating the treating material from the workpieces and recycling the same back to the tumbling machine, said apparatus comprising, a separator cylinder extending outwardly from said tumbling machine substantially along the axis of rotation thereof and having a discharge end, an internal helix in said separator cylinder leading to said discharge end, discharge means interconnecting the separator cylinder and tumbling machine for transferring workpieces and treating material to the separator cylinder for advancement by said internal helix to the discharge end of the separator cylinder, said separator cylinder having apertures for screening the treating material from the workpieces while advancing the same, a collector chamber extending outwardly from the tumbling machine and surrounding the separator cylinder for collecting said screened treating material, said collector chamber having an internal wall which slopes downwardly toward the tumbling machine for advancing the screened treating material back to the tumbling machine, a return tube extending along said axis of rotation from the collector chamber toward the charging end of the tumbling machine, and a return scoop interconnecting the collector chamber and return tube for transferring the screened treating material to the return tube, said return tube having an internal surface which slopes Y downwardly toward the discharge end of said tube, whereby the treating material is 'recycled continuously from the collector chamber back to the charging end of the tumbling machine during rotation thereof.

9. In a rotatable tumbling machine for treating a continuous stream or" workpieces in the presence of loose treating material, said tumbling chamber having a charging end, an apparatus for separating the treating material from the workpieces and recycling the same back to the tumbling machine, said apparatus comprising, a separator cylinder extending outwardly from said tumbling machine substantially along the axis o rotation thereof and having a discharge end, an internal helix in said separator cylinder leading to said discharge end, a discharge scoop interconnecting the separator cylinder with the tumbling machine for transferring workpieces and treating material from the tumbling machine to the separator cylinder for advancement by said internal helix to the discharge end of the separator cylinder, said separator cylinder having apertures for screening thetreating material from the workpieces while advancing the same, a collector chamber extending outwardly from the tumbling machine and surrounding the separator cylinder for collecting said screened treating material, said collector chamber having an internal wall which slopes downwardly toward the tumbling machine for advancing the screened treating material back to the tumbling machine, a heating element associated with the collector chamber for heating the surface thereof to a dehydration temperature, whereby the screened treating material is dehydrated during advancement toward the tumbling machine, a return tube extending along said axis of rotation from the collector chamber toward the charging end of the tumbling machine, and a return scoop interconnecting the Vcollector chamber and return tube for transferring the dehydrated treating material to the return tube, whereby the dehydrated treating material is recycled continuously from the collector chamber to thecharging end of the tumbling machine during rotation thereof.

References Cited in the lile of this patent UNITED STATES PATENTS