US2420748A - Tumbling mill - Google Patents

Description

May 20, 1947. G, M, HOWARD 2,420,748

TUMBLING MILL Filed July 21, 1944 2 sheets-sheet 1 May 20, 1947. G. M. HOWARD A TUMBLING MILL Filed July 2l, 1944 2 Sheets-Sheet 2 DISCHARGE INVENTOR 660i e /W/ioward Patented May 20, 1947' UNITED ys'frlrrEs PATENT OFFICE TUMBLING MILL George M. Howard, Cincinnati, ohio Application July 21, 1944, Serial No. 545,892

4` Claims. l

This invention relates to la tumbling mill of the type used for finishing the Vsurfaces of metal articles and parts to remove spurs, `and similar surface roughness and projections vthat result, for example, after casting or molding of such articles. This ii-nishing is accomplished by the use -of suitable abrading elements commonly known as stars, but which are Afrequently Voi spherical form,.such as ball bearings,

.An `object of the invention iis -to provide a tumbling mill of character in which the articles to be. inished or polished are placed in the tumbling drum througha :side opening therein ,and similarly `removed therefrom, whilet'he abradingelements require no handling whatever, being injected into or emptied .from the tumbling drum by rotation -of :the latter in one direction or the other.

Another object of the invention is the provision of an end compartment associated vwith the tumbling vdrum into and from which the abrading elements may be passed through .a conduit exteriorly of the tumbling drum and communicating with the side of the drum and with said compartment.

Another object is the .provision ofnovel means for mechanical handling of the abrading elements whereby the tumbling drum may be emptied of or replenished with' the elements in a few revolutions of the drum.

Another .object is the provision in a mill of the kind described, of novel means for passing air currents through the drum and the associated compartment means whereby dust and particles are carried oil' during all movements of the abrading elements and operated in the tumbling mill.

Another object `is to provide cross-currents of air passing through the tumbling mill for effectively contacting all parts of and materials in the mill.

Another object is the provision of a mill incorporating the features mentioned and constructed in a simple and eiicient manner.

'I'hese and other objects are attained by the means `described herein and illustrated in the accompanying drawings in which:

Fig. l is a side elevational view of a tumbling mill of this invention with the tumbling drum door vin open position, and with parts of the mil-1 broken away for the sake lof disclosure.

Figs. 2, 3, 4 and v5 are cross-sectional views on the ' lines 2, 3, 4 and 5 respectively of Fig. 1.'

6 is a detailed vcross-sectional view showing the connection between the tramp iron trap 2 and the associated sleeve-forming parts of 'the tumbling mill.

One of the chief disadvantages of Vtumbling mills as now known is the length of time required to empty and replenish the mill, not only as to the articles operated upon but likewise as to the abrading elements utilized. The present invention greatly Aexpedites these operations by providing a side opening tum-bling drum into which the articles operated upon may be inserted and removed instantly and by providing, in addition, lateral openings in the tumbling drum Aand means associated therewith for excluding the operated articles but receiving the abrading elements and passing the latter exteriorly of the drum, upon rotation of the latter in one direction into a compartment, the same conduit means being operative upon reverserotation of `the drum, for returning the abrading elements to the latter, these emptying and replenishing operations being accomplished within a few rotational movements of the drum.

Another Vdifficulty heretofore in devices of the kind here under consideration, has been the carrying oli of dust and `minute particles, an operation essential for the provision of a proper working environment. The lpassage of an air current through a tumbling mill has been previously `utilized but the eifect has been only partially satisfactory since the current of air cuts a more or less direct path through the drum and contacts only a portion of the parts and materials in the mill. The present invention eliminates this disadvantage by providing means to create irregular, divergent and cross-currents of air through the mill so that the dust and particles are effectively carried off.

Other advantages ofthe invention will become apparent 'upon consideration of the details of disclosure that follow.

With reference to the several iigures, the tumbling mill of this invention is mounted for horizontal rotation and comprises a tumbling drum I`2 which may be generally octagonal in cross-section as shown in Fig. 2 which shape has been found to produce an eiective tumbling action. One of the surfaces thus provided may be substantially cut away as at I3 to provide an opening through which operated articles are inserted into `and removed from the drum, this opening being suitably closed by a door I4 conforming in shape to the contour of the associated drum part, the door being suitably held in its closed position by convenient closure means as indicated at I5.

At opposite sides of the drum, the contour of the latter is interrupted to provide a pair of longitudinally-extending openings I6 and I1, Figs. 2 and 3, which are employed for removing from and restoring to the drum, the abrading elements utilized therein. Each opening I6 and I1 has associated therewith a pair of shallow walls I8 and I9 projecting angularly of the surface of the drum and extending divergently from the center of the respective openings I6 and I1, to the ends of the drum, and forming guides for the abrading elements entering or leaving the openings I6 and I1, as will be further described. As seen in Fig. 2, the inner end edges of these shallow walls I8 and I9 connect with the respective edge portions of the interrupted drum sections which form the openings I6 and I1. At each end of the drum I2, a compartment 20 and 2| is secured, the compartments being thus rotatable with the drum, and the inner end walls of the compartments closing the ends of the drum, as indicated at 22 and 23, Fig. 1. The two compartments, as seen in Figs. 2 and 3, are of somewhat larger cross-sectional outline than that of the drum I2 and they are preferably of circular form. The said inner end walls 22 and 23 of the two compartments are each provided, at a point exteriorly of theY drum I2, and substantially midway between the openings I6 and I1, with a pair of ports 24 and 25, one of the ports being provided at each outer end of the respective guide walls I8 and I9.

The mill is mounted for horizontal rotation between standards 26 and 21, Fig. 1, through the medium of shafts 28 and 29 which extend respectively through the compartments 20 and 2l and which have their inner ends secured as at 30 to the inner end walls 22 and 23 of said compartments. The outer` ends of shafts 28 and 29 are suitably retained in roller mountings as at 3| and 32.

At one end of the mill, as on the standard 21, Fig. 1, drive means, such as the reversible motor 33 are provided, movement therefrom being transmitted to the mill by a chain and sprocket unit 34, or other suitable connection, operating on the shaft 23.

Each of the compartments 20 and 2| is provided interiorly with a spiral guide or rib 35 and 36, the ends of which are secured adjacent and diverge away from the respective ports 24 and 25 as indicated at 31, Fig. l, so as to carry abrading elements away from or toward the said ports, depending upon the direction of rotation of the mill, as will be further described.

'I'he present invention involves the use of air currents passed through the tumbling mill for removing dust and particles therefrom. For this purpose a suitable source of air under pressure is provided exteriorly of the mill and is transmitted thereto through a suitable duct 38, Fig. l, this duct likewise serving to carry off the removed dust particles. It is contemplated herein that suction be applied to the mill through this duct. That is to say, air is drawn into the mill at the end opposite the one where the suction is applied. I n the present embodiment of the invention, the said opposite end is represented by the outer` or end wall cf the compartment 2l, which as seen in Fig. 4, may be provided with openings 38 which, interiorly of the compartment, are covered by perforate plates 40. Air may thus be drawn through the compartment 2|, into the drum through the adjacent diagonal conduits and the openings I6 and I 1, thence outwardly of the drum 4 through the conduits and ports at the otheuand of the drum, after which the current of air is drawn outwardly through the compartment 20 and into the duct 38. Within the compartment 20, the shaft 28, is surrounded by a perforated sleeve 4I which extends outwardly beyond the outer end of said compartment, the extreme outer end 42 of the sleeve being sealed about the shaft 28.

The outer end portion of the sleeve 4I is shown as associated with a tramp iron trap 43 which is in eiTect merely a box member embracing the sleeve 4I and provided with openings through which the sleeve passes. The edges of these openings, as indicated at 44, Fig. 6, are in sealed but slidable relation with the sleeve 4I. As shown, the sleeve for this purpose may have a pair of slightly spaced annular angular strips 45 between which the edge portions 44 of the box apertures are slidably retained.

The bottom of the trap 43 may have a hinged door 46, Fig. 1, associated therewith, this door being provided with suitable means for automatic opening thereof when a predetermined amount of weight has been deposited on the interior face of the door. At the upper end of the trap 43, the latter is placed suitably in communication with the duct 38, as shown in Fig. 5.

In operation, the articles to be finished or abraded, such as castings, are placed in the tumbling drum through the opening I3 and thereafter the door I4 is closed and secured. It is to be understood that the drum has already been provided with a charge of suitable abrading elements, such as ball bearings or stars. It should be further explained that the present mill in accordance with common practice, is intended for operation upon articles or objects larger than the abrading elements utilized in the mill. The driving motor 33 is now started for turning the mill in the tumbling direction, as indicated by the arrow at the right-hand side of Fig. 1 and at the left-hand side of Fig. 2. After the tumbling operation is completed, the driving motor is reversed for rotating the mill in the discharge direction indicated by the arrow at the left-hand side of Fig. l and at the right hand side of Fig. 2. At this time, the abrading elements, which are of such size as to be received in the lateral openings Ii and I1 in the drum, are caused to enter the said openings and are then directed by the shallow guide walls I8 and I9 to the ports 24 and 25 at each end of the drum, the abrading elements being thus carried exteriorly of the drum into the end compartments 20 and 2|. Here the spiral guides 35 and 36 further direct movement of the abrading elements to the interior of the associated compartments. The door I4 on the side of the tumbling drum may now be opened for the removal of the nished castings or other articles and another batch of unnished articles may be placed in the drum, the door being again closed thereafter. The mill is now rotated in the opposite direction at which time the spiral guides 35 and 36 in the compartments 20 and 2 I, become operative for directing the abrading elements outwardly through the associated ports 24 and 25 and through the diagonal guides associated with the drum, to the interior of the latter, through the openings I6 and I1. The back and forth motion of the abrading elements as just described is unrestricted and as it takes place simultaneously at both ends of the drum, the emptying and replenishing Operations are accomplished in a minimum of time, normally requiring only a few turns of the mill.

Simultaneously with the abrading operations just described, currents of air are passed through the mill, including the drum and the end compartments, in the manner already indicated. In as much as the currents of air induced into the right-hand end of the mill, Fig. 1, must traverse diagonal paths in entering the drum through the slanting star conduits, and must likewise follow similar diagonal paths in leaving the drum, the air is given a swirling motion and likewise a cross-current action, in as much as the ports 24 and 25 are oppositely disposed. In other words, the mass of air drawn in at one end of the drum, passes outwardly therefrom not only through the opposite end of the opening Il through which the air may have entered, but likewise passes outwardly through the ports 24 and 25 at the opposite end of the drum. The result of such air action is that a thorough scouring of all the interior of the drum, the compartments, and their contents is effected.

With regard to the tramp iron trap it may be urther explained that some relatively large particles of metal may be carried outwardly by the current of air. The drop in air pressure occurring within the trap 43 is sufficient to cause such particles to drop outwardly of the sleeve 4l onto the inner face of the door 45, which, after it has accumulated a predetermined weight of such particles, swings open to release the same and then automatically closes.

Variations will suggest themselves upon consideration of the means herein described by these, are believed to be comprised within the spirit and scope of the invention.

What is claimed is:

1. A tumbling mill comprising a tumbling drum formed with a diagonal conduit leading into a side of the drum and with an outlet, and means for inducing a current of air into the drum through said conduit and out of said outlet whereby a swirling air current is passed through the drum.

2. A tumbling mill comprising a tumbling drum formed with oppositely-disposed conduits leading into and out of the drum, and means for inducing air through said conduits to produce swirling and cross-currents of air through the drum.

3. A tumbling mill comprising a tumbling drum formed with a diagonal conduit leading into a side of the drum and with an outlet, and means for inducing a current' of iluid into the drum through said conduit and out of said outlet whereby a swirling fluid current is passed through the drum.

4. A tumbling mill comprising a drum for receving articles to be abraded and abrading elements smaller than said articles, said drum having a peripheral outlet formed to permit passage of the abrading elements only, a compartment at each end of the drum, and each compartment having a port formed therein, divergent, abrading element guideways disposed exteriorly of the drum and extending between said outlet and the ports, an air opening formed in one compartment, a source of air under pressure, and means for connecting the air source with the other compartment whereby the divergent guideways create a swirling air current within the drum to carry orf dust and dirt particles therefrom.

GEORGE M HOWARD.

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

UNITED STATES PATENTS Number Name Date 726,511 Curtis Apr. 28, 1903 1,549,943 Whiting Aug. 18, 1925 1,642,632 Titgen Sept. 13, 1927 1,765,291 Titgen June 17, 1930 1,996,227 Allan et al Apr. 2, 1935 2,209,080 Gurtelmeier July 23, 1940 2,359,944 Schummer Oct. 10, 1944 2,101,196 Ransohoi Dec. 7, 1937

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