US1996227A - Tumbling mill - Google Patents

Description

pr'il 2, 1935. J, R ALLAN ET AL 1,996,227

TUMBLING MILL April 2, 1935. J. R, ALLAN Er AL TUMBLING MILL Filed April 5, 1934 2 SheeS-Sheeil 2 Patented Apr.' 2, 1935 TUMBLING MILL James R. Allan, Oak Park, and Frank H. Amos,

Chicago, Ill., assignors to International Harvester Company, a corporation of New Jersey Application April 5, 1934, serial No. 719,114

9 Claims.v

I This invention relates to tumbling'mills for smoothing and cleaning `rough castings and the like. Castingsy taken from vsand molds are usually placed in .tumbling mills along with irregular shaped elements to facilitate the tumbling operation for removing sand and metallic iinsfrom the castings. formed as a barrel-like drum or casing, `or of polygonal cross section journaled for rotation. A door is provided for insertion of `the castings,

which is then-securely closed and the casing,

is rotated until the `desired tumbling action has been accomplished. v

Ina tumbling mill, the sandv particles-being removed from the castings are ground toa dustlike material which ,escapes from themill and fills the air of the plant around the mill. Such dust formation is very injurious to the workers in a foundry and constitutes at the present time one of the greatest industrial hazards. To remove the dust from the mill it has been past practice to perforate the ends of -themill` and pass ablast of air through the tumbling drum during the tumbling operation. This method has been only partially successful, because the loadiof castings fills the cross section of themill and thereby oifers-asusbtantial reductionin mill cross, sectional area available for the proper volume and velocity of air to carry away the dust and dirt created by the tumbling action. Also, as a large percentage ofthesandfwhen removed from the castings is too yheavy to be carried by the available air blast through thecenter of the mill, it falls `by gravity to the lower edge and keeps sliding around with the rotation of the drum until it is ground into powder form and leaks through the mill joints. As the castings tend to mat together, in a sense, in thelower half of the casing, the air blastdoes notpenetratey these castings with sufcient velocity to pickup the dust particles.

The principal object of the present invention is to provide an'improved Ventilating means for a, tumbling mill. A more speciiic object is to devise a Ventilating system which can be4 readily applied to a conventional'millofthe type'now in use, as well as to a new mill.V v Another object is to shortenr up the tumbling operation by getting the sand and dirt out ofthe mill at the Vlocation at'which it tends to accumulatev in the present style of mills. Another object is to improve the mill operation, particularly. for small castings, byV using smooth, imperforate end Walls, thereby reducing breakage. These and other objects, whichv will be ,apparent in theV detailed descrip-v The tumbling mills are often tion'to follow, are attained by a construction such as illustrated in the drawings, in which:

Figure- 1 is a vertical cross section of a tum-v bling mill incorporating the improved ventilation system;` Y, ,H

Figure 21s a section taken ,on the line 2-2 of Figure jl; Y l Figure 3 is a Vertical cross sectionof a contemplated mill', showinga modified form of con.

struction; and, z

Figurefl is a. section taken onthe line 4 4 of Figure 3. s Y- As illustrated,A a long cylindrical drum I0, which maybe formed vof sheet steel welded or rivl eted togethenor by any other means, is provided with a removable door I I, through which castings U may be inserted and removed.` 'At diametrically opposite locations along the Wall of the drum I0,

a series of perforations I2 is formed. At each end of the cylindrical drum, circular head members I3 are also provided in a central area with Va series of perforations I4; A head retaining member I5 is secured at one end of the casing to the cylindrical `wall'of the drum It, forming'anabutment; for theiendmember ISat that end. The central portion of the member I5 is spaced axially away from the perforated portion vof the memberV I3 to form an air inlet chamber I6. -A series of circumferentially arranged openings I l formair in;

lets to the chamber I6. At its center -portion the v,

member I5 has a projecting portion I3, inwhich a bearingv sleeve I is mounted. The bearing sleeve forms a raceway forroller bearings 20. The inner raceway for said bearings is provided by the projecting end of ashort shaft 2| rigidlyY secured to a supporting standard 22.

A large ring gear 23 secured to the end member I5 providesmeans for'rotatingthe drum by means of a driving gear 24 mounted on a shaft 25, to which-power is supplied from any suitable source.

At the other endv of the drum I0; a head retaining member 26 is secured by a peripheral liange to the outerend of the drum forming an abutment for the member I3 at that end. The central portion of the memberl is formed With an axially directed extension v2l, iwhichjforms Van outlet chamber 28- for the ,perforations inV the member I3. Beyond'the extension 21, an additional, axially directed extension `29, somewhat smaller indiameter, forms anr extension ofthe chamber 28. I Axially beyond the extension 29, an axially directed 'extension Bl'l'forms a sleeve in which a bearin'gisleeve 3 I` is mounted; Said'sleeve same structure and supported in the` same manner as at the other end of the drum, and identiiied by the same numerals.

A partition 32 closes oi the chamber 28. In addition to the air inlet openings I4 to said chamber, two diametrically positioned openings 33 are formed in the periphery of the extension 27. Said openings are in radial alignment with the rows of openings I2 inthe drum. At the sides or" the openings 33, spaced, radially and axially directed walls 34 extend outwardly to the flanged portion of the member 26, the edges of said walls lying in a plane passing through the end of the drum I0. y Y f Conduits 35 formedby channel-shapedmembers 36 extending axially of the drum over the perforations I2 connect with radial conduits 3lflormed by radial extensions of the members 36, which radial portion is designated by a numeral 38. At the left end of the drum, as illustrated, the channel-shaped members 35 abut the peripheral portio'n of the ringfgear 23, the opening 353 being formed for inlets to the conduit formed by said member. The construction at each side of the casing is exactly the same, there being two diametrically positioned conduits 35 and corresponding radial conduits 31. The side walls ofthe channel-shaped members 38 abut the walls 3S andare secured thereto and also to the peripheral wall of the extension 2l, to formrdust tight seals. These channel-shaped members may be secured by arc-welding or by any other suitable method by which a dust tight joint may be obtained.

Acasing 43 is mounted aroundthe extension supported by the standard 22 atthat end. Said casing forms a dust and air receiving casing and is connected by a conduit 4I with suction producng means.` The outer wall oi'said conduit is fitted around the extension 30 by a suitable seal to prevent the escape of dust or inlet of air. The other side of the casing is fitted around the extension 29 by a seal T42, to prevent the escape of dust or the inlet of air. The chamber 28 communicates with the casing 43 by openings 43 formed in the member 2,6 between the extension `A29 and the extension 30 ofreduced diameter. A

Series of fins 44 are shown extending inwardly from the periphery of the extension 21. Said fins tend to distribute thel air blast and prevent the accumulation of foreign material in the chamber 2B.'

In the operation of a tumbling mill as above describedfthe articles and the elements used in the tumbling operation are placed inthe mill and it is rotated at the desired speed. Suction produced by a suitable source draws air through the conduits and through the openingsA V. A current of air is produced through the center of the drum, passing in through the openings I 4 at the leftend, as-illustrated, and out through the openings I4 at the right end. In addition to this current of air, air ows through the conduits 35 and 3.1 into the air inlet casing. As the particles of sand and'other foreign particles, such as metallic dust, fall by gravity to the outer edge of the drum during rotation, this material sifts through the openings I2 in metered amounts during each revolution of the drum and is'picked up by the relatively high velocity air blast in the through the mass of castings within the tumbling mill.

The modification shown in Figures 3 and 4 is somewhat different in that the air is supplied by a duct through the supporting trunnion, whereby it may be taken in from an outside unheated source. The volume of air used in an installation of this type is such that to take in air from the vicinity of the drum, heating of the building in which the machine is installed may be seriously interfered with. The modiiication of Figures 3 and 4 also diiers in entirely eliminating axial iiow of air through the drum and thereby making possible the provision of smooth end walls which do not engage and interfere with Ythe free tumbling of the castings.

In Figures 3 and 4, the cylindrical drum 45 is formed with a circular head 46 at each end, carrying integrally therewith a hollow trunnion 4l. Said trunnions are rotatably supported by standards 43. A gear 43 at one end of the drum provides means for rotation by the application of power from a driving gear 5I). At each end of the drum 45, a smooth circular end plate 5I is positioned in spaced relation to the head 46. Spaced radially extending walls 52 form a pair of automatically aligned air passages 53. Said passages communicate with the hollow trunnions 4l. Cone-shaped projections 54 from the end walls are provided to form a passage of substantially uniform velocity, the area of the passage l 55 inthe hollow trunnion being substantially the same as the Vsum of the cross sectional areas of the two passages 53. In alignment with the outer ends of the passages 53 and communicating therewith, channels 56 are arranged along the drum and secured thereto by welding or by other suitable means. Said channels are substantially the same in cross sectional area as the passages 53, whereby a substantially uniform velocity of air prevails throughout the entire system from the inlet end to the discharge end. The air passages 57 formed by the channels 56 communicate with the interior of the drum by a plurality of small orifices 578. These orices provide means as above set forth in describing the operation of the other form shown in Figures l and 2 to receive sand and metallic particles loosened from the castings. As the drum rotates, a certain amount of sand'collected is delivered to each passage 51 by gravity as the channel 56 passes the bottom position. By a construction of this type a high uniform air velocity is prevalent at all times in the Ventilating system, whereby the material dropped into the system is completely carried away without any tendency to accumulate at various points. Moreover, as there is noarea restricted or of large cross section, there is no reduction of velocity at any time or at any location.

' As previously stated, the modification of Figures 3 and 4 diners from the form of Figures 1 and 2 Vin not having perforations in the end walls 5 I. In practice, it has been found that the changes in airY velocity broughtabout by either lowering the cross sectional area or by increasing the restriction when end` openings are'utilized` is a serious problem. Also it has been found that a smooth end wall is preferable to obtain satisfactory tumblingoperations, as even small perforations sometimes prevent free tumbling action adjacent the end walls.

It is to be understood that applicants have shown their improved tumbling mill as a particular type to be built up originally with the Ventilationsystem incorporated'.V It to be un- Cil derstood, however, that thek ventilation system of the invention may be incorporated in various types of mills and may be added to conventional All such modifications and.A

mills now in use. uses as are covered by the following claims are considered as part of the present invention. What is claimed is: 1. A ventilated tumbling mill comprising a supporting structure, a tumbling drum rotatably mounted on said structure, a Ventilating conduit extending along ,said drum and carriedA mounted on said structure, a conduit mountedk on said drum, openings formed in the conduit and communicating with the interior of the drum, means for admitting air exteriorly of the drum to one end of said conduit, and means for withdrawing dust and air from the other end of the conduit. Y

3. A Ventilated tumbling mill comprising ar supporting structure, a tumbling drum rotatably mounted on said structure, means for driving said drum, a plurality of Ventilating conduits extending lengthwise of the drum, means for admitting air to said conduits at one end of the drum, and means for removing air and dust from the conduits at the other end of the drum, said conduits being in communication with the interior of the drum by a plurality of openings formed along the conduits and extending through the tumbling drum.

4. A Ventilated tumbling mill comprising a supporting structure, a tumbling drum rotatably mounted on said structure, a plurality of ventilating conduits extending'lengthwise of the` drum and carried thereby, said conduits being separated rfrom the interior of thedrum by perforated walls, means for admitting air to the conduits at one endof the drum, andl means for removing air and dust from the conduits at the other end. Y

5. A ventilated tumbling mill comprising a supporting structure, a cylindrical tumbling drum rotatably mounted on a horizontal axis on said structure, means for driving said drum, a plurality of Ventilating conduits extending lengthwise of the drum, means for admitting air to said conduits at one end of the drum, a plurality of openings formed in the conduits providing communication between the interior of the drum and the conduits, means opposite the inlet'ends ofy said conduits forming a common dischargechamber, a discharging conduit mounted on the sup- ,thereto through the perforated wall.

rality of channel-shaped members extending s lengthwise of the drum and secured to the outer surface thereof, perforations being formed in the wall sections of the drum covered by said members, means for admitting air at one end of the drum to the conduits formed by said members and the enclosed perforated portions of the drum, and means for removing air and dust Afrom the conduits at the other end ofthe drum.

Y 7. A ventilated tumbling mill comprisinga supporting structure, a cylindrcaltumbling drum rotatably mounted on a horizontal axis on said structure, means fordriving said drum, a plurality of channel-shaped members extending lengthwise of the drum and secured to the outer surface thereof, perforations being formed in the wall sections of the drum covered by said members, means for admitting air at one end of the drum to the conduits formed by said members and the enclosed perforated portions of the drum, and means for removing air and dust from the conduits at the other end of the drum, said means including a stationary casing mounted on the supporting structure, a common discharge means carried by the drum and communicating with said sok casing, and means for connecting the Ventilating l conduits with said discharge chamber.

8. In a Ventilated tumbling mill having arotatable tumbling drum and in combination theretending along said drum and carried thereby, a perforated wall between the conduit and the drum forming communication therebetween, means for freely admitting air to one end of the conduit,v and means for withdrawing air from the other end of the conduit effective to produce an air stream of substantialvelocity through the conduit.-

9. In a Ventilating tumbling mill having a rotatable tumbling drum andin combination therewith, a Ventilating conduit extending alongV said drum and carried thereby, a perforated wall between the conduit and the drum forming a restricted communication therebetween whereby a metered amount of dust and other material may be delivered from the drum to the conduit with a minimum amount of air, means for freely admitvting air to one end of the conduit, and means stantial velocity through the conduit eifective to `pick up and carry away material delivered JAMES R. ALLAN. FRANK I-I. AMOS-,

with, a Ventilating and dust removing conduit ex-

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