US1239368A - Process of and apparatus for polishing explosive powder. - Google Patents

Description

I F. 1.- nu FONT. PROCESS OF AND APPARATUS FOR POLISHING EXPLOSIVE POWDER.

APPLICATION FILED JULY 28,1915.

Patented Sept. 4, 1 917.

4 of the powder,

orrrcn IEEi-ANSIS I. no POINT, OF WILMENG-TDN, IDELAVTARE, ASSIGNOR, BY DIRECT AND MESNE HTS, T9 BALL GRAIN EXELQSZVES COMPAQ (Y,

EATIQN OE KYEL' WARE.

GE 'WILMINGTON, DELA- Pa tentcd'Sept, 4:, 1 391? Application filed July 23, 1915. Eerie Ho, $2,266.

To aZZ whom it may concern:

Be it known that l, l ner-tors l. DU Pour, a "zen 0r United States, residing iington, county of cw Castle, and of Delaware, have invented a new and improvement in Processes of and atus 0: Polishing Explosive Powder, hich the following is a lull, clear, and exact description, reference being had to the adrzompanying drawings, which form a part of. this specification.

The object of my invention is to polish or use explosive granular powder. In the finer-y process or" glazing powder, a large yabout one to two tonsis placed arr-cl three to four feet in diter and from six to eight feet in length barrel is filled from one-half to tworzs full and is rotated on its axis at such L ced that the grains of powder slide over nether until they are sutliciently ieced and. polished. The operation is the powder is glazed,

d until at.

' operation is attended with "ger and not infrequently c. plosions occur, Such explosions invariioly result in the total destruction of the mill mdin the loss of the lives of any w orlo men r 0 may be on the premises at the time oi the explosion. No matter how carefully the operation is conducted, the danger of. era plosion remains. Y Instead of attempting primarily to remove or diminish the danger of the ignition.

to which efforts have hitherto been directed, my invention contemplates diminishing the destructive effects of the em plosion to such an extent that, in the event or explosion, there will be practically no 1.3 anger of injury either to the operatives or to the machinery. My invention also conplatcs effecting this result while at the same time rendering the operation continuous and more nearly completely automatic and without reduction or output or sacrifice of efiiciency but on the contrary with an actual increase in both these factors.

it is apparent that when a large amount oi powder is in the form of a compact and confined In its ignition necessarily producs as vi nt explosion, whereas if the same quantity of powder were spread out over great area or strung out in a long line, ignition would cause to burn rather than to explode with force, thereby immensely reducing its destructive effects. However, it is impracticable to thus distribute and mechanically handle, at any given time, a volume of powder that would be contained in a barrel six to eight feet long and three to four feet in diameter, while if a substantially smaller quantity were handled, the operation would not be feasible commercially.

in my invention 1 accomplish the results sought, without sacrifice of any essential factor, by so distributing and handling the powder that at any given time only a comparatively small quantity or": powder is undereoing the polishing operation, while this smaller quantity of powder is so widely distributed that in the event of explosion no damage will result except practically negligible damage to the powder container, At the same time the speed of the operation is in inverse proportion to the quantity of powder at any given time undergoing treat:

inent, thereby causing no decrease in output. Additionally, provision is made so that the operation may be conducted continuously instead of intermittently, thereby increasing the output, reducing labor, and diminishing the chances of accidental ignition.

The invention may be best explained by first referring to the accompanying drawings, in which Figure l is a cross-sectional diagrammatie view of my improved apparatus for carrying out my improved process Fig. 2 isa longitudinal sectional view of the same.

In place of the usual barrel l provide a tube which, :t'or example, may be eight inches in diameter and thirty-two feet long. The iube is revolved as on rolls n. A feed chute 0 delivers into an opening in one end of the tube and at this end there is a short section oi a spiral f, fixed in the-tube and flaring in the direction to start the material moving toward the other end of the tube. A free space at s 's left between the spiral and the flange at the end of tlic'tube, into which space the material is fed, and even though the level at this point is low, the efiect of the spiral is to fill the tube continuously to as much higher level as may be desired. This level is regulated by the diameter of the hole 6 at the delivery end of the tube. Thus hycontinuously supplying explosive powder through the feed chute o and revolving tube m at a certain speechtlie niaterial gradually fed along throughout the length of the tube and overflows out of the opening a, maintaining; an active polishing or glazing zone the full length'olthe tube.

1 hove discovered that, in any polishing barrel, the powder actually being upon given time is not "he'entire mass of \vder in the barrel but onlyla comparatively thin Thus, Fig. 1 represents the actior the material in polishing is rotating; in the direction of the arrow. he material climbs up the side of e barrel and when the particles have reached a point well up toward the top, they tumble down the exposed face. it is only in this tumbling down operation that the .ins rub or slide upon one another and lQCQll a po h, and it is only in the c inparat vel y thin zone represented at that this operation occurs. Thus the amount of powder being glazed at any given time depends upon the area of the active zone {assuming a given speed of movement of the grains} and not upon the hull; of powder in the container.

For example, it may readily be calculated that barrel 6 feet long and l feet in diameter will contain six times as much powder a tube 8 inches in diameter and 361i'eet long, bu the area of the active zone, assum ing that botn containers are half full, will be as great in the tube of small capacity as in the barrel of large capacity. if, therefore, the tube is rotated at such greater angular speed than the barrel as to impart to the individual grains the same desirable speed of travel as in the barrel, it is clear that, at a given time, much powder is being glazed in the tube as in the barrel and that the entire contents of the tube will be glazed in one-sixth the time required to glaze the entire contents of he barrel.

It will thus be seen that within any given time the output of my improved polishing apparatus will be as great as the output of the ordinary glazing barrel, assuming no loss of time in filling and discharging the barrel. in fact, liowe xer, this loss of time is not a negligible factor and therefore the output of my improved apparatus may actually be increased, if desired, over that of the ordinary polishing barrel, while at any given 55 time a very much smaller quantity of powder is being glazed nd the same is so widely distributed that, in the event of ignition, it will burn like a fuse rather than explode like a confined charge. Indeed, actual experience shows that the only efiect is to spread apart the staves oi'the tube to allow the flame to escape, and, aside from the charring of the wood were by the burning powder, the machinery "of the mill is not injured barrel, which l hile, therefore, it is essential to invention that the long h of the powder mass be great role vely to its depth, while it is the tube is half filled, such tial factor is, therefore, the relation between length and depth of powder niass. Experiment has shown that, in the event of ignition oi? the powder, burning with flame, as disiguished from explosionwith destructive force, cannot be assured, in a commercial plant, unless the ratio between length and deph of powder mass is at least ll to l, with a maximum depth of eight inches of powder mass; or, in the event that the tube is about half -filled, its diameter must not exceed 16 inches, while the ratio between its length and radius should be at least will b understood that the substitution e of te elo. gated tube of relatively small capacity having comparatively rapid an, ;u-

of rotation for the compact bar will be understood that the invention is applicable either to the smoot iening' of powder preparatory to final glazing with graphite or other polishing material, or to the final glazing; after the smoothening operation.

Having now fully described my invention, what I claim-and desire to protect by Letters Patent is:

1. The process of polishing explosive granular powder which consists in distributing the powder longitudinally to form an elongated. string, iinpartirg to'the powder a movement of rotation on an axis parallel to its forward progressing movement, applying a forward propulsion force directly to the powder throughout only a relatively small part of itslength and restricting the advance of the powder at the far end of the string to regulate and maintain its depth.

'2. The process of polishing explosive granular powder which consists in distribthe str' and. throughout a relatively short messes length of the string, impar ing to the powder a movement of rotat on on an axis parallel to its forward progressive movement while eliminating all chstruction to the free rolling of the grains one upon another, and

regulating the depth of the string indestring, imparting to the powder a move ment of rotation on an axis parallel to its forward progressive movement while elnninating all obstruction to the free rolling of the grams oneupon another, and restricting the advance of the powder at the other end of the string to regulate its depth.

4. The process of polishing explosive granular powder which consists in distributing the powder longitudinally to form a string having a length not less than approximately fourteen times its maximum depth, imparting to the powder a turning move-- ment on an axis parallel to its longitudinal y direction of extension, and controlling the desired depth by restricting its longitudinal flow.

5. In an apparatus for polishing explosive powder, the combination with a tube of comparatively great length and small diameter,

its interior, throughout the greater part of its length, being open and free of obstruction to tumbling of the powder, of means to feed the powder into one end of the tube, and means occupying a relatively short part of the length of the tube to insure the forward travel of the powder within the tube.

6. In an apparatus for polishing explosive powder, the combination with a tube of comparatively great length and small diameter, of means to rotate the tube, feeding means to introduce the powder at one end thereof, and means within the tube and occupying a relatively short part of its length and positioned at the inlet end thereof to start the powder through the tube. a

7 In an apparatus for polishing explosive powder, the combination with an elongated rotary tube, of feeding meanr to introduce the powder at one end, propulsion means occupying only a relatively short part of the length of the tube to effect the propulsic-'11 of the powder toward the discharge end, and means controlling the discharge and determining the depth of the material in the tube.

8. In an apparatus for polishing explosive powder, the combination with a tube of cone paratively great length and small diameter, of means to rotate'the tube, feeding means to introduce the powder at one end thereof,

propulsion means occupying a relatively short part of the length of the tube-and pesitioned at the inlet end thereof, and means at the discharge end of the tuloe to regulate the depth of powder therein 9. In an apparatus for polishing explosive powder, the combination with an elongated rotary tube, of means to introduce the powder at one end thereof, a section of a spiral at the inlet end portion of the tube and turning therewith, the discharge end of the tube having a central hole whose diameter regulates the depth of powdr in he tube.

10. In an apparatus for polishing explosive owder, the combination with an elongated at its inlet end, of a hopper feeding into the inlet end thereof, and a section of a spiral fixed to the tube at its inlet end portion but spaced from the extreme inlet end, the dis charge end of the being conical and provided with a central. open FRANCES I. on FONT,

rotary tube, having a central opening

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