US3430532A - Means for making pellets,particularly explosive pellets - Google Patents

Description

March 4. 969 J. K. AMPBELL 3,430,532

MEANS FOR MAKING PELLETS, PARTICULARLY EXPLOSIVE PELLETS Filed July 13, '19s? Sheet 2 or e r F g? 40 March 4, 1969 J. K. CAMPBELL 3,430,532

MEANS FOR MAKING PELLETS, PARTICULARLY EXPLOSIVE PELLETS Sheet Filed July 13, 1967 Inventor Lfean, K Campbell By his Attorney March 4, 1969 J. K. CAMPBELL 3,430,532

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MEANS FOR MAKING PELLETS, PARTICULARLY EXPLOSIVE PELLE'I'S Filed July 13. 1967 Sheet 4 of e March 4', 1969 J. K. cAmmaeu. 3,430,532

MEANS FOR MAKING PELLETS, PARTICULARLY EXPLOSIVE PELLETS Sheet Filed July 15, 1967 M 4 @Q q @RM Nb m \S v E %w .sw w j w wk m A 3 EE 5 J. K. CAMPBELL March 4, 1969 Sheet Filed July 13. 1967 3,430,532 MEANS FOR MAKING PELLETS, PARTICULARLY EXPLOSIVE PELLETS Jean K. Campbell, Portland, Oreg., assignor to USM Corporation, Boston, Mass., a corporation of New Jersey Filed July 13, 1967, Ser. No. 653,136

US. Cl. 86-1 14 Claims Int. Cl. G09b 15/02 ABSTRACT OF THE DISCLOSURE Apparatus and process for continuously making fibrous articles, especially explosive pellets, of precisely uniform size and Weight. A nonexplosive slurry carrying the explosive material is vacuum fed into die cavities, the solid material in the slurry is entrapped therein by being caused to do its own filtering, next trimmed to form intermediate slugs of predetermined size and weight, then further compressed gradually to substantially final form, and lastly ejected from the respective dies.

Background of the invention This invention relates to mechanism and a method for accurately producing fibrous articles with uniform shape and weight, and by way of illustration is particularly directed to precision forming of explosive pellets, for instance those of the cartridgeless, fibrous nitrocellulose type disclosed in a copending application Ser. No. 524,- 168, filed Feb. 1, 1966 in the name of Robert C. Kvavle, now issued as United States Patent No. 3,372,643.

Pelleting presses and pill or tablet making apparatus have long been commercially available. It is acknowledged that it is Well known to use fibrous nitrocellulose in the manufacture of various propellants. Safe production of explosive pellets in quantity and with a high degree of uniformity in size and density, an important goal as regards the unique cartridgeless charge referred to, cannot be accomplished by techniques heretofore practiced or with any material forming machines presently known. Problems and hazards incidental to the handling and treatment of nitrocellulose in or out of a slurry are many, a few being indicated for example in such US. patents as Nos. 3,139,355, 3,037,417, 3,260,203 and 2,967,098. Sensitivity of the explosive material to molding pressure and to heat is Widely known, as is the danger inherent in a production system conducive to a working atmosphere wherein dust of the material may exist. Also, where fluid has hitherto been employed as a medium for the fibrous material, which by itself quickly mats and resists flow, it has been customary, and indeed considered invariably essential, to provide an aqueous substance or emulsion with a resin binder, a plasticizer, or a casting solvent. The simpler technique herein disclosed not only overcomes problems previously encountered but insures reliably consistent energy levels in the output which are essential to power graded propellants.

Summary of the invention In the light of the foregoing, a general object of the invention is the provision of an efficient and safe process and apparatus for manufacturing fibrous articles with precision in weight and form. A more specific object is to provide such a method and means advantageous in the commercial production of explosive nitrocellulose pellets nited States Patent 0 which are reliably uniform in character and hence in potential energy.

The present invention features in this instance a slurry consisting solely of water and fibrous nitrocellulose in a ratio on an order ranging from 5:1 to about 12:1, and a stabilizer such as diphenyl amine, the slurry being continuously delivered to apparatus including vented pockets in the form of die cavities wherein excesses of fluid and fibre beyond what is desired are eliminated systematically in sequential steps to produce homogeneous, uniformly shaped and sized charges. To insure that successive die cavities receive at least a minimum initial quantity of slurry at a loading zone, each die cavity is connected to a source of reduced air pressure, the venting holes also being used to withdraw and exhaust excess moisture from the slugs subsequent to loading the cavities and prior to forming by cooperation of a pair of upper and lower forming punches working in each die cavity. Especially important to quickly charging each cavity with its complete load of fibres, while making certain that no air pocket or bubble forms to prevent this objective, are the purging by suction of the cavity as it is loaded and the fact that the fibres retained are thus caused to do their own filtering. Preferably, unused slurry being circulated, as well as the purged slurry and excess nitrocellulose removed prior to final pressure-forming in the dies, are recirculated so that there is no wastage of materials, solid or liquid.

The fibrous materials entrapped as indicated is subjected to vacuum drying beyond the cavity loading zone, air being drawn through the slugs, and next undergoes a novel series of sizing and shaping operations effected by cams controlling relative forming movements of the forming punches with respect to one another, and with respect to the mentioned vents, and a unique material cut-off mechanism. The latter, as herein shown is arranged to operate at a work station following the cavity loading zone and preceding the work forming stations. The lower forming punch is raised to an accurately adjustable, predetermined distance from the top of the die cavity thus to close the vacuum exhaust vents and cause projection of an unwanted portion of the moist fibrous slug material into the severance area of a fluid cut-off jet, preferably of water, the jet and the slug relatively moving to define a precise cutting line. Thereafter the upper punch cooperates in the die cavity with the lower punch progressively to form an exact remaining mass of the explosive fibers into the precise shape and density desired.

At an eject station following a final work compressing zone, the upper punch is retracted from its die cavity, and the cooperating lower punch urges the formed fibrous article out of the cavity whereupon fluid pressure, preferably both air and water, ejects the article from the machine. In the illustrative machine the emptied cavity may now recirculate through the loading zone.

Brief description of the drawings While the invention will herein be described with reference to a rotary press type pelleting machine and with regard to making explosive pellets of the low explosive type set forth in the Kvavle application mentioned above, it will be understood that the invention is not limited in its machine aspects to the particular organization herein shown, nor is it necessarily restricted in process or structural aspects to the manufacture of any particular article or shape, explosive or otherwise.

The foregoing and other features of the invention, including novel details in construction and method, will now be more particularly described in connection with an illustrative embodiment thereof, and with reference to the accompanying drawings, in which:

FIG. 1 is a view in front elevation of a rotary press type pelleting machine for producing explosive pellets of fibrous nitrocellulose according to my novel method;

FIG. 2 is a vertical section of the machine shown in FIG. 1, and taken along the line IIII therein;

FIG. 3 is a perspective view of an upper portion of the forming head of the machine, covers and guards being removed to reveal working structure such as a fluid jet trimming and a loading head;

FIG. 4 is a section, somewhat schematic, showing a die cavity being loaded beneath the head shown in FIG. 3;

FIG. 5 is a section, also somewhat schematic, showing the fluid jet trimmer of FIG. 3 and associated exhaust mechanism;

FIG. 6 is an axial section showing a pair of formers at one stage of compacting a slug;

FIG. 7 is a perspective view of a pellet formed in the machine;

FIG. 8 is a linear projection showing relative heightwise positions of the upper and lower formers throughout a cycle of operation as reflected by operating cams indicated;

FIG. 9 is a schematic view corresponding to FIG. 8, and indicating the sequence of functions in each cycle;

FIG. 10 is a plan view of cams controlling the lower formers; and

FIG. 11 is a horizontal section, with portions broken away, showing some of the dies in relation to loading, trimming, and pellet ejecting means.

Referring to FIGS. 1 and 2, the illustrative machine comprises a fixed cast frame having a lower base portion 10 and an integral upper bearing column 12. This column carries a rotary forming head 14 supported on a thrust bearing 16 (FIG. 2). For receiving and segregating particulate material in the form of fibres, in this instance nitrocellulose circulated in a slurry consisting only of water and a stabilizer, the head 14 in this instance is formed with cylindrical bores 17 (FIGS. 4-6) respectively disposed to receive a plurality of circularly arranged, equispaced tubular dies 18; a total of 24 dies being used in the exemplary machine. As will be explained, the segregated fibrous material is to be partly dried, made uniform as to volume, and then progressively compressed into discrete, precise shapes, in this instance low explosive pellets P as shown in FIGS. 7 and 9. Accordingly 24 pellets per complete cycle of the head 14 are produced. In a manner somewhat resembling known ordinary tablet making presses, the respective dies 18 in the course of their revolution receive in their cylindrical cavities 19 (FIGS. 3-6) cooperative, vertically alined, upper and lower formers 20, 22, respectively, important distinctions in structure and method being hereinafter noted.

For driving the head 14, a variable speed motor-reducer 24 (FIGS. 1 and 2) is connected by an endless belt 26 to a pulley 28 (FIG. 2) on one end of a cross shaft 30 the other end of which drives meshing bevel gears 31, 32 (FIG. 1). The gear 32 is rotatably connected to the head 14 by means including a stub shaft 34, and a pinion 36 thereon meshing with a ring gear 38 affixed to the head.

Vertical positioning of the upper formers is controlled by an upper pressure roll 40 (at the zero degree position in the diagram of FIG. 8 and in FIG. 9) and a cam 42 having a circular cam track formed to receive followers 44 on the respective upper ends of the formers 20. Similarly, the lower formers 22 are respectively provided at their lower ends with followers 46 (FIG- 2) arranged to cooperate in succession for purposes later to be explained, with a circular series of cams, namely, a lower pressure roll 48 (FIGS. 1 and 2) cooperative with the roll 40 for effecting maximum compression of the pellets P, a pellet eject jam 50 (FIG. 10), a former retract cam 52, a holddown cam 53, a cut-off adjust cam 54, and a preeompression cam 56. It will be understood that, except for the roll 48 these lower cams are here shown as fixedly secured to the frame 10, but that the invention contemplates that the cams, or their equivalent, need not be circularly disposed and that, in fact, they may in alternate arrangement (not shown) he in motion relative to formers operative in fixed vertical or other paths. The upper cam 42 is secured to a bracket 58 bolted onto the column 12, the bracket serving with an upstanding rear portion 60 (FIG. 2) of the frame 10 rotatably to support a bearing shaft 62 for the upper pressure roll 40.

For adjusting and precisely determining final forming compression effected by the rolls 40, 48 and hence creating the desired porosity of the pellets P, the lower roll 48 is floatingly carried by linkage including a lever 64 (FIGS. 1 and 2) one end of which is pivoted to the frame 10 and the other end of which is pivotally connected to a link 66 (FIG. 1). The latter is itself carried by a lever 68 one end of which is pivoted to the frame 10 at 70, and the other end of which is yieldingly supported on a plunger 72 urged upwardly by resilient means such as a compression spring 74 (or an air actuated diaphragm is preferred) carried in a cylindrical housing 76 secured at its lower end to the frame 10. The plunger threadedly carries a hand wheel 78 by means of which the plunger can be moved accurately heightwise, and hence the degree of resistance to final compression of a pellet by the roll 48 selectively adjusted to determine pellet density.

Description of additional structure will now continue in the order of its function in a cycle of operation of the machine, considering this cycle to commence at a zone generally designated 80 (FIGS. 2, 3, 9, 11) wherein the dies 18 are to be loaded.

The slurry is preferably constantly stirred in a storage vat and continuously recirculated in a supply and return system including a delivery pipe 82 (FIGS. 1-3) connected to a feed head 84 over-lying the loading portion of a fiat table 86 (FIGS. 2, 3, 9) constituting an annular portion of the head 14. The tops of the dies 18 preferably are secured even with the surface of the table 86 as by means of die locks 88 (FIGS. 3 and 11) respectively inserted radially in the table 86. Preferably pumping means, not herein shown in detail, is provided for maintaining the circulation of slurry under an adjustable, selected pressure. The feed head 84 is formed with a cavity 90 (FIGS. 2, 4, 9, 11) preferably of a configuration to overlie more than one of the die cavities 19, in this case up to three consecutive cavities 19, as shown in FIG. 11. The feed head 84 also has communicating with it an outlet pipe 92 for returning unused slurry to be recirculated. In the loading zone 80 the upper formers 20 are retracted out of the dies to positions above the feed head 84, and the lower formers 22 are caused to descend in the loading cavities to a level determined by the retracting cam 52.

An important feature of the loading zone 80, and in subsequent operating stations as will be noted, is the provision of a multipurpose suction means communicating with the cavities 19. Before describing this suction means, it should be noted that the formers 20, 22 preferably have a stem diameter, adjacent to their respective forming ends, which is just enough smaller than that of the cavities 19 to afford a radial clearance allowing the passage of excess water to be exuded yet tending to obstruct the passage of solid materials such as nitrocellulose fibres. In order ultimately to produce finished pellets P of uniform density and size, it is essential to retain for processing in the cavities 19 and adjustable, precisely selected volume of the fibrous material. To this end, the fibres are accumulated in the form of a wet slug S (FIG. 5) on the lower former 22 as exactly positioned in the die cavity 19 by the cam 53, their matting and the initial cavity purging to insure rapid, complete charging being induced by a suction means in the form of an evacuable chamber or conduit 94 (FIGS. 1-3, 11) communicating with the cavities 19 being loaded. By placing more than one die cavity under the feed head 84 and subjecting these to vacuum exhaust simultaneously, uniform loading is attained since surging peak demands on the vacuum pump are lessened. Preferably, for drying purposes, a right-hand section of the chamber 94 as shown in FIGS. 3 and 11 also communicates with at least one previously fully loaded cavity 19. It has been found that without the aid of this suction means the cavities 19 are not reliably loaded to the level required; moreover, the cavities 19 preferably communicate with the conduit 94 through radial table vents 96 and a plurality of radial die bores 98 (FIGS. 4 and 5) of a reduced diameter on the order of .040" for passing water and obstructing the fibres to facilitate their matting and slug build-up.

In FIGS. 4, 5 the die bores 98 are inclined downward toward the die cavity 19 thus affording a longer slug S than when, alternatively, horizontal or upwardly inclined die bores 98 are employed as illustrated in FIG. 6. As best seen in FIGS. 4, 5 and 11, outer ends of the vents 96 extend into a circular groove 100 in the table 86, the conduit 94 having spaced sealing means engaging the groove for maintaining effective exhaust condition. The conduit 94 has exhaust outlets 104, 104 which are in communication with a manifold 106 (FIG. 2) secured to the frame portion 60.

On emerging from the feed head 84 the successive dies 18 will have been loaded with wet fibres matted to form the slugs S (FIGS. 5, 9) bottomed on the lower former 22 and having a rough irregular upper surface. It is in this condition that the exhaust conduit 94- performs its final drying treatment. The slugs next progress through a cut-off station generally designated 108 (FIGS. 1, 3, 5, 9, 11) where each successive lower former is caused by the cam 54 to move upwardly to block the vents 98 and then project the irregular unwanted upper portion of the slug above the table 86 and into the operating path of slug trimming means now to be described, thus leaving an exact predetermined mass of pellet material to be formed.

As shown in FIGS. 3 and 5, the slug trimming means preferably comprises a block 110 having a passage 112 for supplying water under pressure in a continuous fine jet from an orifice 114 (FIG. 5) arranged to emit its jet in a cutting path substantially parallel to the upper surface of the table 86. No mechanical trimming or wiping means appears to safely or precisely excise the surplus nitrocellulose in the effective manner of the jet. The feeding head 84 and the block 110 are mounted on the conduit 94, and the latter is secured on a support plate 116 secured to the base 10. For recirculating the waste jet water and the removed excess slug material, an exhaust passageway 118 in the block 110 communicates with the manifold 106. All recirculated fluid may pass through a precipitating zone (not shown) wherein waste nitrocellulose is recaptured for reuse.

Referring to FIG. 8, after slugs S are trimmed, both upper and lower formers 20, 22 descend in their dies 18, and then, while the bores 98 remain blocked by the formers 22, commence relative vertical movement together as they pass through a precompression zone as shown in FIGS. 6, 8 to effect gradual compression and forming of the slug. Too rapid compression, even though the fibres are still moist, can effect an explosion since the compacted fibres are now pressed against and confined within the substantially closed cavity defined by the circumferential wall of the cavity 19 and the adjacent ends of the formers 20, 22. The forming punches are in this instance preferably provided with web forming annular projections 120, respectively, to produce a symmetric pellet P (FIG. 7) having an internal web 122 which is thinner than other portions of the pellet. Porosity of the web 122 usually does not significantly differ from the remainder of its pellet and is usually uniform to serve ultimately as a bridge in transmitting burning from a central impact ignition locality 124 to the thicker outer pellet walls. Final compression of the pellets may be effected in the apparatus described, between the rolls 40, 48, which apply pressure only slightly greater than the maximum of the precompression zone, or if desired, such final compression can be effected in a separate press adapted for the purpose. By way of example only, nitrocellulosic pellets P having a diameter on the order of .340" are subjected to a final compression of about 5000 lbs.

After progressing through the rolls 40, 48, the upper formers 20 are reelevated to out-of-the-way positions above the dies 18, and the lower formers 22 are successively raised by the eject cam 50 to thrust the formed pellets P axially from the cavities 19. As soon as the formers 22 have effected pellet ejection, they are retraced within the die cavities 19 by the cam 52 to reopen the radial bores 98 thus to enable air under pressure to be admitted thereto from a tube 126 (FIG. 11) having communication with groove and the bore 96. This scavenging air blast lifts the ejected pellet, which is still slightly soft but stable enough to be handled, from the mouth of the die bore sufficiently to be carried by a water jet from a supply pipe 128 directly into an exit tube 130. The latter is normally inclined downwardly and away from the apparatus to deliver the pellets P into a wire mesh container, for example, or onto a suitable conveyor (not shown) Where the carrying water is collected and recirculated. The cycle is now completed and the dies 18 are ready to start once again through the loading zone 80.

The described apparatus has been found effective, safe and efficient in the production of fibrous articles of selected uniform Weight and size. Thus, for instance, uniform propellant charges of nitrocellulose fibre have been produced in lots having, respectively, selected net weights varying from about milligrams to roughly twice as much, with a tolerance range of only about plus or minus 5-10 milligrams per charge. Experience indicates that density of propellant charges may advantageously be slightly varied as. desired for different production batches by pursuing one or more of the following steps:

(a) Changing the proportion of water to nitrocellulose in the slurry,

(b) Changing the pressure under which the slurry is circulated,

(c) Changing the duration or strength of the drying suction,

(d) Changing the mass of slug material retained for compression forming, and

(e) Changing the degree of compression applied to the moist slug.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. Apparatus for continuously making articles of predetermined shape from fibrous material comprising:

(a) a table,

(b) a plurality of spaced, tubular dies carried thereby,

(c) a pair of reciprocable formers cooperative in the respective dies,

(d) means for flowing a liquid fibre-containing slurry onto a loading zone of the table and into each die when one of its associated formers is retracted,

(e) exhaust means effectively connected radially to said dies for complete rapid filling of the die cavities in said zone with slurry by purging fluid slurry therefrom, the locality of the die and exhaust connection being disposed to be substantially interrupted by advancement of said one former,

( f) cam means for controlling relative movement of the formers in said loading zone and throughout their subsequent working engagement with the entrapped fibre and final ejection thereof, and

(g) means for relatively moving the table and the cam means cyclically to operate the formers.

2. In a machine for making articles of predetermined size and weight from particulate material flowable in a slurry, a plurality of dies successively disposed to have their respective cavities receive a portion of the slurry, pairs of relatively movable formers cooperative in the respective die cavities, suction means for causing the solid slurry material to accumulate in a slug of a predetermined depth in successive die cavities on one of the formers of each pair and then be subjected to exhaust drying for a predetermined time, said suction means being effectively connected radially to each cavity at a locality to be substantially interrupted by advancement of said one former to purge the cavity of fluid slurry and thereby accelerate the accumulation of slug material, a slug trimming means operable adjacent to a die which has had its slug thus partially dried, and means for relatively positioning said one former and the trimming means to position the slugs relative to the operating path of said trimming means whereby the slug material remaining with said one former is selectively sized for subsequent processing by the respective pairs of formers.

3. A machine as set forth in claim 2 wherein means is provided for conveying the dies in succession along a path for cooperation with the suction means and the slug trimming means.

4. A machine as set forth in claim 3 wherein said trimming means consists of a device for emitting a jet of Water transversely of the successive slugs.

5. Apparatus for making explosive charges including fibrous nitrocellulose of uniform size and weight, comprising a plurality of dies each formed with a bore, means for supporting said dies in spaced arrangement with the axes of their bores parallel, a plurality of pairs of cooperative formers respectively operable along said axes of the die bores, cam means for moving the formers axially of their respective bores, mechanism for relatively moving said die supporting means and the cam means sequentially to control the relative axial movement of the successive pairs of formers, a fluid recirculating system for delivering to a loading zone of the die supporting means including at least one of the dies a slurry wherein nitrocellulosic fibers are entrained, exhaust means communicating with the bores of successive dies in said loading zone, said exhaust means being adapted to accumulate the slurry fibers in a die bore to provide a slug on one of the formers and partly eliminate fluid from the slug, and fluid jet means mounted external to the loading zone for trimming successive slugs a predetermined distance from the respective formers on which they are accumulated, said cam means being operable external to said loading zone for causing one former of each coacting pair to eject from its die the trimmed slug which has been compressibly formed therein by said pair.

6. Apparatus as set forth in claim 5 wherein said dies are respectively formed with a plurality of passages extending radially outward from said bores for communication with said exhaust means, at least one of the passages having a portion of a cross section formed to impede the flow of said fibers while allowing the drainage of fluid therefrom.

7. Apparatus as set forth in claim 6 wherein said cam means is adapted to cause said slug supporting formers axially to position the successive fibrous slugs predeterminedly for intersection with the operating path of said fluid jet means to effect removal of a waste end portion of each of the slugs.

8. Apparatus as set forth in claim 6 wherein the cam means includes a pair of pressure rolls for causing the pairs of formers cooperatively and adjustably to determine the density of the explosive charges to be ejected from the dies, one of said rolls being mounted for rotation about a fixed axis, and means mounting the other of said rolls for rotation on an axis yieldably and adjustably spaced from said fixed axis, the last-mentioned mounting means including a linkage floatingly supporting said other roll and a resilient means connected to said linkage for resisting separation of the rolls.

9. Apparatus as set forth in claim 5 wherein the formers of each pair have their adjacent ends provided with cor responding web-shaping projections, and said cam means is formed in part with straight, converging cam surfaces cooperative to cause said adjacent former ends progressively to exude liquid from the trimmed slug and compact it to a pellet of predetermined overall thickness having a web of substantially uniform relative thinness.

10. In apparatus for precisely molding explosive pellets from wet nitrocellulose, a die having a bore, a reciprocable former operable in the bore and having substantially the same diameter, as said bore, loading means including an exhaust vent communicating with the bore to accumulate and segregate from a slurry introduced therein the fibres of nitrocellulose to be molded, a nozzle mounted for directing a liquid jet under pressure transversely of one end of the bore, and power actuated means sequentially controlling the movement of the former to cause it to move a slug of the segregated wet fibres into predetermined posi tion to be trimmed by the jet, then gradually to apply compacting pressure up to a predetermined maximum to the trimmed slug to be molded in the die, and finally to eject from the die a moist pellet of selected density formed from the compacted slug.

11. In apparatus as set forth in claim 10, mechanism for moving the die relatively transversely of said loading means when the die is full of the segregated wet nitrocellulose fibres, and means for reducing the wetness of said fibres during their loading and for an interval prior to operation thereon of said liquid jet.

12. Apparatus as set forth in claim 10 and further characterized in that, immediately following the pellet ejecting operation of said one die, fluid pressure means is operatively connected to said vent to direct fluid through she die bore for aiding in removal of the pellet from its 13. In apparatus for automatically and continuously producing explosive nitrocellulosic articles of precise shape and weight,

a table disposed in a plane,

a plurality of dies formed with central bores respectively corresponding to the peripheral surface of the articles to be formed, respectively, therein,

means for detachably securing the dies individually in the table with one end of each of the bores lying substantially parallel to said plane and their axes extending normal thereto,

a plurality of pairs of upper and lower formers respectively mounted for cooperative movement along said axes,

cam means for controlling the axial movement of said formers sequentially in the course of relative normal movement of the table in said plane,

feed means for gravity loading successive die bores with a watery slurry of fibrous nitrocellulose,

purging exhaust means communicating radially with the successive bores being loaded for rapidly and completely filling them with slurry initially and then partially solidifying therein slugs having at least a predetermined volume of the fibrous nitrocellulose,

the locality of communication of said purging exhaust means with the die bores being arranged to be substantially closed by movement of the lower former,

means for removing any portion of a slug in excess of said predetermined volume, and

9 means for causing one of the formers of a pair to eject a pellet formed therebetween in their die when they have compacted the slugs of predetermined volume to a final volume of selected density.

14. Apparatus as set forth in claim 13 wherein means is provided for collecting for reuse slurry from the purging exhaust means and the waste portions removed from the slugs.

References Cited UNITED STATES PATENTS 901,937 10/1908 Scott 10717 2,043,086 6/1936 Westin et al 10717 Tochner et a1 1820 X De Boer 1820 X Besser et al 861 X Quinn 18-16 Royer et a1. 1820 Rayburn 18-16 BENJAMIN A. BORCHELT, Primary Examiner. G. H. GLANZMAN, Assistant Examiner.

US. Cl. X.R.

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