US2416746A - Tube mill and method of operating same, including discharging - Google Patents

Description

March 4, 1947. F. J. GAVIN 2,416,746

TUBE MILL AND METHOD OPERATING SAME INCLUDING DISCHARGING Filed Aug. .4,- 1943 Iooooo l 2 Inveni'or':

" attorney-r.

Rank J. 14in,

Patented Mar. 4, 1947 UNITED. STATES P TENT. oFFicE;

TUBE MILL'AND METHOD. OF OPERATING SAME, INCLUDING DISCHARGING' Frank J..Gavin, Baltimore, Md.',.assignor toICroWn 'ori-:,& Seal Conripany,Linc. Baltimore, Md:-, 2:.

corporation of New York Application august-4, 1942, serial No. 497,370

(Cl. 241F301 5 Claims. '1

The present invention relates to improvements in method and apparatus, for reducing materials in mills. of the. ball type and for effecting the discharge of the reduced material from such mills. As for the reducing operation, it. is an object of the invention to enhance the effectiveness of the disintegrating action by causing the disintegrating media to move in a path or circuit 1 which increases their impact, as opposed to attritive, action. As for the discharge operation, it is an object of the invention to enable thereduced material to be discharged alone by main .taining the charge of disintegrating media stable in the mill. How these objects may be accomplished will be described with reference to the accompanying drawings wherein:

Figure l is a side elevation of 'a mill inaccordance with the inventiomf Figure 2 is a section on line 2-2 of Figure 1;

Figure 3 is a section on line 3-3 of Figure 1; j

Figure 4 is a section online 4-4 of Figure 1 with certain elements removed; V

Figure 5 is an elevation of a detail; and

Figure 6 is a transverse section of the detail appearing in Figure 5'. i

In my application Serial No. 346,452, new Patent No. 2,334,258, granted November 16, 1943, of which the present application is' a continuation-in-part, the herein-disclosed mill was disclosed as an adjunct toaprocess of making-finely divided metal, particularly aluminum powder, useful in the coating arts. It will be understood, however, that; the improvements which constitute the present invention are useful in mills of the ball type regardless of the nature of thematerial to be reduced.

Referring to Figures 1, 2 and 3 ofthedrawings, reference numeral l designates generally a drum which comprises'a cylindrical shell II which is bolted to axially extending lifters l2 througha cylindrical liner l3. The endsof the drum are closed by circular plates as at I4, Figures 2 and 3, and secured to these end members centrally thereof are hollow trunnions which are journalled in bearings at the upper ends of pedestals l and i6 on an axis which is horizontal, or generally so. Midway between its ends the drum is provided with a charging opening closed by a removable cover I! and opposite the charging opening is a discharge opening which is: closed 2 ported by this shaft within the drum in generally radial relation and in the same plane are a number of arms 2l' which are longitudinally slotted to receive bolts 22 which securea plate or apron '23 against one side of the arms with the capability of radial adjustment. The plate 23' extends from end to end ofthe drum with slight end clearances and projects radially into-adjacency with the circle described by the inner extremities of the lifters l2. The width of the plate 23 is such that a space 2% exists between its inner edge and the shaft 211. The shaft 20 projects outwardly of the left-hand. trunnion, Figure 1, and-has fixed thereto a worm wheel 25 which is engaged bya worm-26 whereby shaft 20. may be rotated to adjust plate 23'to various positions for the purposes which will be hereinafter. ex-

plained; the worm automatically locking the shaft in adjusted position. The drum contains a charge 2 1 of disintegratingmedia, here shown as steel balls, the proportion .of material to. be reduced to. the balls being generally maintained, for example, ataboutl to 15 to 1 to 20 by weight. When. the mill. is to be placed in operation the shelf 23f is preferably adjusted to the up wa'rdly extending:positionv shown in dot and dash lines in. Figure. 2 unti1'the,.-mi1l has attained its operating speed. and this, speed is less than critical, i. e., insufiicientto cause the balls to be carried around by, centrifugal force in. the pockets between the lifters"; This means that the balls will be carried upwardly adistance on the, ascending, inner wall of the drum and. then will tend to tumble or cascade downwardly with a. largely attritive effect on the material to be reduced. However, in' accordance with the invention, after. the operating speed of the drum has been attained the plate 23 is adjusted, by clockwise rotation of the shaft 20, to a position like that shown in Figure 2 wherein it extends toward the ascending wall of. the drum so as to be. able to catch the media tumbling from the top of the-ascending layer and direct them toward the center of the drum to dropthrough the opening-24 on tothe material to be reduced so that a predominantly impact action is afforded. In other words, at-least a large portion of the charge is caused to follow a loop-like path between the ascending and descending sides of the drum in contact with the former and clear of the latter. Preferably, the clearance between the outer edge of apronZB and the circlelo'f the innerextremities of the lifters. is less than the diameter of the minimum ball sizeso. thatall ballsawhichare lifted-above the apron. will have v the discharge opening.

the time required to effect reduction.

Whenthe reducing operation has been-completed, shaft is rotated to bring plate 23 into a downwardly extending position and continued extending coaxially into said drum and supporting said plate for adjustment edgewise into fixed positions toward and away from the inner periphery of the drum, means for rocking said shaft to bring said plate to a position wherein it projects toward the bottom of the drum to serve as a barrier. for holding a charge of disintegrating media away from said discharge opening when the latter is in discharging position at the bottom rotation of the drum causes the ball charge to be 7 localized between the plate and the ascending side of the drum. After this has occurred, rota tion of the drum is arrested with the, discharge opening at the bottom and atthe opposite side Bolts 22 are,-

of plate 23 from the ball charge. loosened and plate -23 is lowered close to the liner so as to serve as a complete barrier for the charge,

as shown in Figure 3. If the drum is stopped with the lifter which is directly at the right hand side of the discharge pening, Figure 3, in register with the barrier 23, the balls will be completely maintained away from the discharge opening without downward adjustment of the barrier being necessary. Where, as described in the parent application, the material is finely reduced in the presence of considerable liquid, the slurry can now be drained off while the balls are maintained in stable condition against escape through The lifters should be notched immediately adjacent the liner [3, or

their ends should be spaced somewhat from the end walls, or both, so that-the pockets will drain as completelyas possible, but many case the drain openings should not be of suflicient size to pass whichis at or adjacent the top of the drum, or

they may be inserted also through the hollow of the drum.

2. The method of discharging reduced nonmagnetic'material in slurry form from a millof the type comprisinga drum rotatable on a horizontal axis, saiddrum containing a charge of magnetically "attractable disintegrating media and havinga peripheral discharge opening and a cover therefor, said method comprising rotat' ing the drum to position said opening at the bottom of the drum, holding the drum stationary,

exerting lateral force on the charge to holdthe' charge at one side of saidopening and simultaneouslyapplying magnetic force to the charge to lock'the charge together, and removlng the cover and allowing the slurry-to drain through said opening. v 3. "1118 method the type comprising a drum rotatable on a horizontai axis, said drurn contaimng a charge of V magnetically 'attractaole disintegrating media and having a peripheral discharge opening and a cover therefor, said method comprising rotating the drum'to position said opening at the bottomof thedrum, holding the drum stationary, heaping tne charge on a bottom portion of the drum 7 through said opening.

4. The method of discharging reducedj non- I magnetic material in slurry form from a mi'llof trunnions where these are large enough, for

through doors providedin the endwalls. The magnets serve to lock the mass of balls together so thatthe mass is completely stabilized; 1

In Figure 4, the charge is shown as being stabilized by the magnets 28 alone, the magnets being successively placed in position and the balls heaped thereon. Obviously, the magnet system can be used only when the material to be reduced is not subject tomagnetic attraction and with them, when removed from the media, any

foreign matter which is magnetically attractablea Instead of the simple bar magnets shown in Figures 3 and 4, I may utilize a magnet arrangement such as is shown in Figures 5 and 6 wherein reference numeral 29 designates a non-mag netable bar which carries, through clamps 30, a number of aligned permanent magnets 3i in the form of short rod lengths.

It will be understood that the showing'herein is for the purpose of illustration and is not intended to be restrictive of the invention which extends-to all variations in apparatus and procedure coming under the terms of the following claims;

I claim: 7 i

1. The combination with a mill'having a drum rotatable on ahorizontalaxis and provided with a peripheral discharge opening, of a'longitudinally extending plate in the drum,and a'shaft thetype comprising a drumrotatable on a horizontal axis, said drum containing a charge of magnetically attractable disintegrating media and having a peripheral discharge opening and a cover therefor, which comprises rotating the drum to position said opening at the bottom of the drum, holding the drum stationary, heaping the charge on a bottom portion of the drum at one side-of the opening, and embedding magnetic means in the heaped charge to maintain it in position at said one side of the opening, and removing the cover and allowing the slurry to drain through said opening. I g r 5. A mill comprising a drum mounted for rotation on a horizontal axis and provided with a peripheral discharge opening, a shaft extending into the drum coaxially therewith, and an apron in the drum extending lengthwise of said shaft and supported thereby in generally radially extending relation, and means forfixing said apron in a position wherein it projects into adjacency with a layer of grinding media in the drum which is carried upwardly a distance on the ascending inner side of the drum when the drum is rotated at less than critical speed so that the apron re-' ceives the media as they tumble and directs them toward the drum center to drop fromadjacent said shaft onto the material to be reduced, said means being adjustable forfixing said apron in a downwardly projectingrposition so that it can serve to Iretain the grinding medialat' oneside thereof when said discharge opening is at the bot of discharging reduced nona V 7 magnetic material in slurry lorm from a min 'of tom of the drum and at the other side of said Number apron. 1,315,770 FRANK J. GAVIN. 1,583,644

REFERENCES CITED 5 Number 'lne followmg references are of record 1n the 200 280 file of thxs patent: 336:021 UNITED STATES PATENTS 403,820 Number Name Date 10 421,054 1,043,349 Ostwald Nov. 5, 1912 3, 1,242,423 Cover Oct. 9, 1917 1,279 926,441 Shafter June 29, 1909 402,650 1,164,264 Davidsen Dec. 14, 1915 Name Date Hall Sept. 9, 1919 Balletto May 4, 1926 FOREIGN PATENTS Country Date German July 13, 1908 British Oct. 9, 1930 German Oct. 8, 1924 German Nov. 5, 1925 German Apr. 20, 1932 Australian 1931 French Sept. 3, 1909

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