US2775081A - High density encapsulation - Google Patents

Description

Dec. 25, 1956 Filed June 19, 1953 F. E. STIRN ET AL 2,775,081

HIGH DENSITY ENCAPSULATION 6 Sheets-Sheet l MIL Wm ATTO R N EY 1956 F. E. STIRN ET AL 2,775,081

HIGH DENSITY ENCAPSULATION Filed June 19, 1953 6 Sheets-Sheet 2 M WWW Dec. 25, 1956 F. E. STIRN ET AL 2,775,081

HIGH DENSITY ENCAPSULATION Filed Junel9, 1953 6 Sheets-Sheet 3 INVENTORS FiAW/r f. JT/AN,

ATTO R N EY Dec. 25, 1956 F. E. STl RN ET AL 2,775,081

HIAGH DENSITY EINCAPSULATION 6 Sheets-Sheet 4 Filed June 19, 1955 63% RR 1 n o r N T 4 R ma? #0 m w [KP A 3 P7 1956 F. E. STIRN ET AL 2,775,031

HIGH DENSITY ENCAPSULATION Filed June 19, 19.53 6 Sheets-Sheet 5 INVENTORS F/Pfl/VK E. sr/A /v AZTOANEY HI GH DENSITY ENCAP ULATION Filed June 19, 1953 6 Sheets-Sheet 6 United States Patent HIGH DENSITY ENCAPSULATION Frank Edwin Stim, Pearl River, and Arthur Sinclair Taylor, Spring Valley, N. Y., assignors to American (lg/air amid Company, New York, N. Y., a corporation of Maine Application June 19, 1953, Serial No. 362,926

20 Claims. (Cl. Sit-650) This invention relates to improvements in a method and an apparatus for forming and filling capsules from a strip of plastic sheet material, such as soft gelatin, with a pro-compacted high density powder substance.

In the past, it has been customary when administering a powder medication to patients to fill the powder loosely into a two-piece telescopic hard gelatin capsule. Such a capsule necessarily has a comparatively low density of powder. These hard shell capsules frequently come apart, and are not tamper-proof. It has also been customary to package liquids in soft gelatin capsules formed from strips of soft gelatin. Our earlier patents disclose methods of filling such soft gelatin capsules with a loose powder.

In many instances, it is desirable to be able to ,ad minister comparatively large dosages of powder to a patient and, particularly, if the powder has a disagreeable taste or if it is deleterious to the tissues of the mouth, it is desirable that the powder be placed in a capsule, so that the capsule releases the powder after passing the mouth. For such powders it may be desirable to be able to compact as much powder as possible into a minimum size of dosage unit for convenience in administration. While it is known to the medical profession that comparatively large objects may be readily swallowed, the average patient has a psychological block against trying to swallow large capsules.

Hexylresorcinol capsules have been made by sealing hexylresorcinol pills between gelatin sheets in a batchwise essentially symmetrical operation as is disclosed by patents to P-ittinger, Nos. 2,155,444 and 2,155,445 Such a batchwise process involving, as it does, the distribution of the hexylresorcinol pills between preformed sheets of gelatin is a slow, tedious labor-consuming operation.

It is possible by the use of the apparatus and methods of this invention to continuously produce solid filled, soft gelatin capsules of not only round but also elliptical or long oval configuration at a high rate of speed without the necessity for hand labor.

The machine of our invention makes practical the method of filling the capsules by compacting a powder into a tablet or slug. The slugs are preferably approximately rounded, and may be either circular or elliptical. They are fed through a magazine into cavities lined with a strip of plastic sheet material in a rotating die roll. After the deposition of the slug in the plastic strip-lined cavity, a second plastic strip is placed in juxtaposition to the first, covering the slug, after which cutting edges penetrate the two strips, simultaneously sealing and cutting out the portions of the strips surrounding the slugs, thereby giving uniform symmetrical high density powder-filled capsules.

The slugs themselves may be formed by using standard tableting machines with dies for forming slugs of the desired shape. While other shapes may be used, ranging from spheres to lens-shaped tablets or football-shaped tablets, i. e., both oblete and prolete spheroids, what is known in the trade as long ovals, namely, a cylindrical portion with two hemispherical ends is generally preice ferred as giving a maximum volume with a minimum diameter. By appropriate dies fora tableting machine, the appropriatesized and shaped slugs are easily formed. Slightly flat sides may be formed on the slugs due to the characteristics of the tableting machine, and such slugs are easily encapsulated by the machine of this invention. We find it convenient to store the slugs, without regard for orientation, in containers until ready for use.

In feeding our machine, we use a vibratory bowl feeder which consists of a bowl into which the slugs are poured with peripheral channels around the bowl, and because of the rotary vibratory motion of the bowl, the slugs travel to the rim of the bowl and around the bowl in the peripheral channels, and from them, in turn, to feed tubes which may be eithersolid tubes or spiral springs, and thence into the slug-feeding magazines. The tubes must be of slightly greater diameter than the maximum crosssection diameter of the slugs, but should be small enough so that the slugs cannot start to pass each other and jam. Slugs with pointed ends may lodge obliquely in the tube and impair the feeding if too large a tube is used.

Such vibratory feeders are disclosed in U. S. patents to Weyandt, Nos. 2,187,717; 2,305,943; and to Devol, No. 2,464,216, and are sold commercially. Other forms of feeders which deliver oriented slugs at a uniform rate may be used. The slugs are fed through the feed tubes into the top of the magazines, where they orient themselves. For the elliptical and long oval slugs, the magazine is long enough that the major axis tends to assume the horizontal. For lens-shaped slugs, the slugs tend to become horizontal. In each instance, the center of gravity tends to assume the lowest position. The vibration which is conducted from the vibratory feeder to the slug-feeding magazines through the tubes aids in the orientation of the slugs. An additional vibrator may be used. Care must be taken if two vibratory sources are used that the vibratory motions are not permitted to oppose each other and form standing waves .01 nodes at such points as would hamper the uniform feeding of the slugs.

The die roll beneath the slug-feeding magazine may be constructed from one piece or built up and is preferably a cylindrical die with plurality of uniformly spaced, uniformly shaped cavities, each with a. positive ejection means and a raised cutting-out rim and of such size that a plastic strip when placed on the surface of the die roll may be drawn into and caused to line the cavity with an interior size which is slightly larger than the slug, so that the slugs may uniformly drop by gravity into the striplined cavity.

The strip material is conveniently of a gelatin composition consisting of gelatin, glycerin, and water, together with such pigments, dyes and perfumes as may be aesthetically desirable with preservatives and hardening agents as desired. Gelatin substitutes, such as edible plastics, may be used when available and economically practical. Strips of such compositions are well known to those skilled in the art, as are the machines for easting and forming the strips. The strips may be coated on the outside with a lubricant, such as a mineral oil or kerosene, preferably deodorized, or a mixture thereof, so that the strips will not adhere to the die roll or the seal roll or yet will not slide unduly thereon. The side of the strip which forms the interior of the capsule may be coated with gum benzoin, or shellac, gum sandarac, or other material to assist in preventing the materials of the slug from inter-acting with the material forming the strip. Some vitaminaceous fillingmaterials have a tendency to discolor the strip material or inter-act with the moisture of the strip material.

The strip is fed over the cavity die roll and by. suction drawn down into the cavities therein. As the strip material-lined cavities pass beneath the slug-feeding magazine, a single slug drops from the magazine into each cavity, thereby, substantially filling the cavity and retaining the remaining slugs in the magazine until the next empty cavity in turn passes beneath the magazine. As the slug-containing cavities rotate,'a covering strip is placed thereover. A separate roll may be used to place the covering strip over the filled cavities, but we find it particularly convenient to use a sealing roll both to feed the covering strip and to seal and cut out the capsules. The temperature of the seal roll is normally slightly higher than the die roll which causes the sealing portion of the strip to be somewhat more tender than the stretched portion lining the cavity. Thereby, when the film-covered slug is released from confinement, the warmed portion is stretched, as the pocketed portion shrinks so that the sealing line is drawn down to the center line of the slug and a symmetrical covering is produced. By adjusting the temperature of the seal roll slightly, the position of the seal line may be adjusted so as to obtain an equatorial seal.

The seal roll may have recesses, so that the cavities in the cavity die roll need not be so deep, as the slugs extend partially up into these recesses. be drawn into thermal contact with the sealing roll for a sufiicient time that it is uniformly warmed so that in the relief of stresses, it is uniformly stretched.

If the depressions in the seal roll are somewhat smaller than the area of the cavities, as for example when the depressions are adapted to contain only a small portion of the slug during sealing, it is unnecessary to draw the strip into the depression. If the Width of the film contacting portion of the seal roll inside of the die rim contacting portion exceeds about inch (0.8 millimeter), adequate thermal contact is obtained. With less than this, a thin heated line is obtained, which stretches unduly and shows thin spots in the slug covering film.

The amount of air trapped with the slug varies with the size and the shape of the cavity. If the holding vacuum, which retains the cavity lining strip in position is released just prior to the sealing operation, a minimum of air is trapped with the slug in the finished capsule. A small amount of air usually gives a more resilient and less easily damaged finished product. By adjusting the point at which the vacuum is released in the sealing operation, the amount of trapped air may be very easily controlled. The film should preferably appear firmly but not tightly stretched around the slug.

Previously, designers of capsule-forming machines have found it difficult to remove the finished capsules from the cut-out residual web, or net. In the present machine because the cavity die rolls have cavities which are comparatively deep as compared with prior art machines, it is possible to hold the residual strips, now forming a perforated web or net, against the surface of the cavity die roll and eject the capsules and brush them off from the surface of the die roll before the web is released. It is preferred, however, to retain the capsules in the cavities by the application of a holding vacuum, and stripping the web oif by a slight tension, so that the residual net remains on the sealing roll until separated from the capsules and is drawn E to be re-processed. The capsules remaining in the cavities may then be ejected at a convenient portion of their travel around the periphery of the cavity die rolls, conveniently by the positive action of plugs within the cavities. With round or elliptical capsules, there is little danger of the capsules sticking in the cavities, but with long oval capsules in particular, it is desirable to have a positive acting ejector plug at each end to ensure that neither end of the capsule remains stuck in the die roll. Air-operated plungers are particularly convenient for this purpose, and uniform, reliable, and effective ejection may be thus obtained.

Conveniently, the capsules may be ejected into a capsule receiving housing which at its lower portion has a pneumatic conveyor which picks up and carries the The covering strip may 4 capsules to a tumbling drum or receiving tray or other desired location.

The invention is further described in connection with particular embodiments thereof in the accompanying drawings.

Figure 1 is a side elevation.

Figure 2 is a pictorial representation, showing how the strip material is drawn into the cavities and the slugs are fed thereinto.

Figure 3 is a sectional view through a portion of the cavity die roll showing how the slugs feed from the slugfeeding magazine into the strip-lined cavities.

Figure 4 is a detailed view showing a slug directly beneath the magazine.

Figure 5 shows the slugs as the die roll rotates past the magazine.

Figure 6 shows a later stage in rotation in which a slug rests on the surface of the strip during a dwell period.

Figure 7 shows how at the end of the dwell period the next slug slips into the next cavity.

Figure 8 shows a second embodiment with deeper cavities in the die roll, wherein the entire slug is received within the cavity.

Figure 9 is a partial view of the embodiment of Figure 8 showing a cavity directly beneath a magazine.

Figure 10, at a slightly later time, shows the magazine over an interval between cavities.

Figure 11, still later, shows an approaching strip-lined cavity as it receives its slug.

Figure 12 shows a particular magazine having access slots in its face, so that improperly oriented slugs fall out.

Figure 13 shows the sealing action of a recessed seal roll of the first embodiment of the invention.

Figure 14 shows a smooth seal roll in sealing relationship with the deeper cavities of the second embodiment.

Figure 15 is a view of the manifolding plate for a die roll.

Figure 16 is a sectional view along lines 16-16 of Figure 15.

The machine may be designed for any size and shape of the completed capsule. The die roll and seal roll may be changed for various sizes of capsules. The machine will be described in connection with the filling of a particular long oval capsule in which the length of the slug is over twice its diameter. The slugs need not be completely round, and in tableting presses, it is frequently found convenient to have slightly fiat sides as the forming dies are more easily manufactured for this shape. However, for purposes of illustration, the slugs are shown as round and symmetrical.

In Figure 1 a lower plastic strip 21 is supplied from a suitable casting source and is a fresh, soft, thin gelatin film. The strip passes over an oil roll 22. The oil roll is in turn kept oiled by contact with the oil feed roll 23 which rotates partially submerged in an oil bath 24. A suitable oil supply system may be attached to the oil bath to maintain the oil at a constant level therein. A thin mineral oil or a mineral oil thinned with a deodorized kerosene may be used. After passing over the oil roll, the film passes under a positioning roll 25 into contact with an inside coating roll 26, which roll is in turn fed by an inside coating feed roll 27 which rotates in a coating trough 28. It is preferred that the rolls contacting the strip be driven by a suitable drive means so that all stresses in the strip are kept at a minimum. The plastic strip next contacts the cavity die roll 29. The cavity die roll is shown in Figures 1 and 2 and in partial section in Figures 3 and 13. The die roll may be engraved from a single metal blank but is more conveniently built up in structure as is shown in Figure 3. It consists of a die roll blank 30, which has around its periphery a series of slots which contain the capsule cavity inserts 31. Underneath the capsule cavity inserts are the capsule ejector plugs 32, which fit into holes in the bottom of the capsule cavity inserts and extend down into ejector piston cylinders 33. On the bottom .of each of the plugs is a capsule ejector piston 34. One end of the piston cylinder is connected by a manifold 36 to a source of pressure or vacuum which is applied through the valve plate 35. The ejector piston has a small piston slot .37 in it so that the piston head cannot form an air tight seal against the bottom of the cylinder.

The pistons and plugs are fitted with sufficient clearance that a vacuum applied beneath the piston will hold the piston and plug in the withdrawn position, and also draw the strip laid over the surface of the die roll down into the cavities. A clearance of .008 inch (0.2 millimeter) gives excellent results, and also prevents binding of the plug and cylinder. The length of the plug in the cylinder is such that in raised position the top of the plug is approximately even with the top surface of the capsule cavity insert. The length is not critical. The capsule cavity inserts for the long oval capsules are something like a bath tub in configuration having a cutting rim 38 extending above the level of the die roll blank. The top surface of these cutting rims form the cylindrical periphery of the cavity die roll. The rim has semi-circular ends and a straight connecting portion on each side between these ends. The capsule cavity inserts are made of hardened steel in order that a maximum of wear may be obtained before it is necessary to grind the rims. The rims are under considerable pressure and gradually wear out. Small nicks in the rims cause defects in the cutting out operations. The capsule cavity inserts are vshown retained in the die roll by a pressure fit. Mechanical fasteners may be used.

Above the cavity die roll is a slug feeding magazine 39. As shown in Figure 2, this has two slug channels 40, each of which is slightly wider than the length of the slug 93 and each of which has a depth slightly greater than the diameter of the slug. The magazine has a transparent slug retaining magazine cover 41, preferably of a transparent plastic so that the passage of the slugs through the magazine may be observed. The magazine is held in place by a magazine support 42, to which a retaining lug 43 of the magazine is fastened. Retaining bolts 44 are used which are drawn up tight and then backed off enough that the magazine is loosely held in place, so that it may vibrate without being displaced. The vibration induced in the magazine from the bowlfeeder, which is later described, aids in causing the slugs 93 to attain a uniform, ordered, parallel orientation within the slug channels.

Each of the slug channels 40 has leading thereto aslug feeding tube 45 which is a tube of slightly. greater diameter than the slugs through which the slugs are fed axially from a bowl feeder 4-6. The bowl feeder, a commercially available item, as before mentioned, has a bowl in which the slugs are dumped, which is vibrated by an electromagnetic vibrator 47, so that the slugs in the bowl are shaken thus causing them to orient themselves upon peripheral ledges in the bowl and travel along these. ledges to the slug feeding tubes and through the slug feeding tubes to the magazine. The vibration induced through the tubes from the vibration of the bowl causes the slugs to feed smoothly through the tubes and also causes the slugs to feed uniformly through the magazine.

In the face of the transparent slug retaining magazine cover 41 are apertures 48 which permit the operator to orient the slugs in the magazine should they become disarranged. Usually, it is necessary to orient the slugs in starting up the machine, but once the magazines have been filled with oriented slugs, they retain that orientation, subsequentslugs orient themselves, and no difliculty is found in the continuing operation.

The lower plastic strip is drawn into the individual capsule cavity inserts by reducing the pressure inside the cavities. As shown in Figure 3, the strip may be drawn down into the inserts just before the inserts pass under the magazine. As shown in Figures 3 and 4, the bottom slug from the magazine drops into the strip lined insert and remains at such .a height as to prevent additional slugs from escaping from the magazine. As the die roll rotates in the direction shown by the arrows, the slug in the strip lined cavity passes out from under the magazine, and the group of slugs in the magazine are permitted todescend as shown in Figure 5. As a preceding slug containing cavity continues to rotate, Figure 6, the bottom slug then comes in contact with the strip between cavities and slides along this surface until the suc ceeding cavity passes under the magazine. As shown in Figure 7, the following slug starts to drop into the following cavity as the following cavity passes under the magazine. When the slug has fallen completely into the cavity, it is retained therein as shown in Figure 4 and the process repeated. Conveniently, two rows of cavities are contained in the die roll, although any number may be used, and are in staggered relationship, so that they may be more closely placed, and the loss of strip material in the residual net is minimized.

As the slug-containing, strip :lined cavities rotate, an upper plastic strip or second strip of plastic sheet material 49 .is fed wunder an inside coating roll 5t), which in turn contacts a coating feed roll El, which contacts a transfer roll 52, which contacts a partially submerged roll 53, which. rotates in a coating trough 54. The strip then contacts a release coating roll 55, which coats the outer surface of 'the upper strip with a thin coating of a releasing agent, such as a deodorized kerosene, as is more fully described and claimed in our copending Patent 2,674,073, Relieved Non-skid Seal Roll and Method of Use, April 6, 1954. If mineral oil is used at this point, the upper strip may skid on the surface of the seal roll and slide, thereby giving distorted shapes to the capsules. This coating may be applied directly to the surface of the seal roll. The strip is then laid on the surface of the seal roll 56. The seal roll 56 has sealing depressions 57 in its surface and so spaced as to cooperate with the cavities in the face of the cavity die roll. in the modification shown in Figure 13, the slugs extend above the surface of the die roll, so that in sealing it is necessary to have the depressions inthe sealing roll to permit the slugs to partially extend thereinto.

The depressions must be at least deep enough so that the combined depth of the depression and the cavity is at least equal to the maximum slug diameter plus the thicknesses of both strips.

Vacuum manifold passages 58 extend from the bottoms of these recesses to a face of the die roll, so that a vacuum may be drawn in the individual recesses to cause the second strip to smoothly contact not only the outer face of the die roll but also the surface in the recesses. For best results, the die roll is at a slightly warmer temperature than the cavity roll, and thereby, the upper strip is warmed. For uniform Warming of the strip, the strip must contact the seal roll at all portions, and therefore, sufiicient vacuum must be used to draw the upper plastic stripintouniform contact with the seal roll.

A thermostatically controlled electric heating element 94 is used to keep the seal roll at a desired temperature. The temperature may be raised or lowered to adjust the degree of stretching of the portion of the second strip forming part of the capsule, and hence control the symmetry of seal.

The seal roll and the cavity die roll approach and contact .each other, the raised rims of the cavities of the cavity die roll coming into contact with the surface of the seal -roll. The strips on the surface of the two rolls are thus brought into contact with each other, and then the cutting rims 38 of the cavities cut through the two strips, thereby causing them to seal to each other. The operation also severs the thus cut'out portions, which then cover the slug, from the remainder of the strips. As showniin Figure 13, the lower plastic strip is drawn down into the cavity die roll as it approaches the sealing roll position; at position A, the vacuum is broken slightly before the rolls come in contact, which permits the elasticity of the strip to cause the strip to attempt to rise, and thereby, hug against the slug as is shown at position B. The vacuum release point is adjusted so that the slugs are not thrown out of the cavities before the upper strip comes in contact with them. The amount of air trapped with the slug can be varied by changing the vacuum release location. As shown in the next position, the slug at C has both the upper and the lower strips firmly placed about it, and the rim has cut uniformly through the strips at the front of the capsule, but the cutting-out rim has not yet completely severed the strips at the rear of the capsule. In the next position at D, it is seen that the capsule has been completely out out, and the residual Web now forming a net is held against the seal roll and withdrawn from the capsules which are then held in the cavities by a holding vacuum at approximately the point D.

It may be seen that because the seal roll is above the equatorial diameter of the slug, the recess may be a little smaller than the opening in the capsule cavity inserts, and accordingly, any minor errors in positioning between the seal roll and the cavity die roll does not deleteriously affect the seal. Preferably this overlap is wide enough to assist in heat transfer to the second strip.

The finished capsules are retained in the cavities as they rotate around to a capsule receiving housing 59. As the cavity in the die roll passes into the receiving housing pressure is applied within the cylinder under the cavity causing the pistons and the attached plugs to rise, forcing the capsule out of the cavity and into the housing. As the capsules fall into the housing, a pneumatic conveyor 60, which consists of a traveling air jet as reduced pressure picks up the falling capsules and tumbles them through a discharge tube 61. The discharge tube may be adjusted to feed into any desired receiver. The residual strips now form a net 62. The net passes over an idler roll 63 to the net draw otf rolls 64 which are driven at a slightly faster surface speed than the surface speed of the die roll. The net as it feeds from these rolls may be fed to a take-up reel or a container for storage or re-use. It is convenient to remelt the net and use the material subsequently in forming capsules.

The various rolls may be support for a frame 65, which is diagrammatically shown as having the proper supports at the desired locations for the various elements previously mentioned. It is convenient to have the seal roll pressed against the surface of the die roll by hold down pins 66, which are urged by a spring 67 against bearings 68 on the seal roll shaft 69. The pressure between the rolls may be thus easily adjusted, and the springs permit any slight variations in the surfaces of the rolls to even out without unduly heavy pressure being exerted at a particular point.

The die roll 29 has on its face the valve plate 35. As shown in Figure 15, for the plate on the back side of the machine, a vacuum chest 70 is arranged to contact the ends of the manifold connected to the ejector pistons and hold down the plastic strip from the time shortly after it first contacts the cavity die roll until just before the sealing position. A vacuum connection 71 leads to a suitable vacuum source. A second vacuum chest 72 again applies a vacuum to hold the capsules in the cavities as the Web is removed. A second vacuum connection 73 connects this vacuum chest to the vacuum source. A pressure chest 74 with a pressure connection 75 is in such a location as to connect to the manifold passages and in turn the pistons so that the plugs are raised and the capsules ejected as the cavities pass the capsule receiving housing 59. A balancing chest 76 extends around the periphery of the valve plate and has therein a vacuum connection 77. The vacuum in this balancing chest is used to maintain a balance on the plate and keep the pressure in the pressure chest and the otherwise unbalanced vacuum acting on the other side of the plate from lifting or turning the plate. A valve plate positioning bracket 78 extends from the edge of the plate, so that the plate may be angularly positioned by the positioning screws 79; the adjustment of these screws controls the point at which the vacuum is released during the sealing step and thus controls the amount of air which is trapped in the capsule.

Smooth seal roll die syst m Figures 8 to 12 and 14 show a modification of the die roll system in which the individual capsule cavity inserts are sufiiciently deep that a smooth seal roll rotates in contact with the surface of the die roll and the entire plastic strip covered slug is beneath the top surface of the capsule cavity inserts. This modification permits the use of smooth seal rolls. The heat transfer to the seal roll is more convenient, and the problems in timing are markedly reduced. The shallow seal rolls are particularly convenient in slug encapsulation in that the same capsule cavity seal roll which is used for filling liquids or powders. The deeper cavity die rolls, which are deep enough to completely contain the strip covered slugs, are deeper than is normally desired with a liquid or straight powder fill.

As shown in Figure 8, capsule cavity inserts 8t) fit into the cavity die roll blank 81. Restricted orifices 82 extend from the bottom of the capsule cavity inserts and are of such size that jets of air through them may be used for ejection without a complete loss of pressure being permitted through one open orifice. Inasmuch as there are no moving parts, there is nothing to stick. This form of ejection is particularly convenient with spherical or elliptical capsules. The depth of the cavity in the insert is deep enough so as to completely contain the stripcovering slug. As shown in Figure 8, the strip is sucked partially into these cavities as the slugs are fed down thereinto. By using a reduced vacuum and adjusting it properly, the strip is only partially sucked into the insert, and the strip itself acts to seal off the orifice before the strip is pulled into the corners of the insert. If the strip is not drawn down deep enough, the action of the sealing roll will press the slug down into the cavity, and smooth operation is thereby obtained.

As shown in Figure 8, the magazine 83 has a slug retainer 84 in a slot 85. A limiting screw 36 fits in a limiting slot 87 in the retainer, so that the retainer can neither be pressed in too far nor drawn out too far. The retainer may be pressed forward to restrain the supply of slugs during starting and stopping of the machine or if for any reason it is desired to operate the machine in manufacturing empty capsules. In starting operation it is particularly convenient to manufacture empty capsule shells until the temperature conditions and the sealing conditions are adjusted to give proper seals and thus avoid wasting of the slugs in defective capsules. The use of the slug retainers permit independent adjustment of the slug feeding and the strip feeding mechanisms.

As more clearly shown in Figure 12, the magazine 83 has a transparent cover 88, through which the slugs may be seen. Rejection slots 89 are cut in this transparent cover so that any slugs which are non-parallel and which would, otherwise, tend to jam the feed may fall through these rejection slots to a return chute 90, which throws them off to the side of the machine from which they can again be recycled to the bowl feeder. Figures 9, l0 and 11 illustrate the feeding of slugs from this particular magazine into the full depth capsule cavity inserts, showing in Figure 10 how the slugs ride along the surface of the strip on the face of the cavity die roll until as shown in Figure 11 the bottom slug drops into the subsequent strip-lined cavity.

It is preferred that the strip not be drawn completely into the cavity, so that as shown in Figure 9 the falling slug does not drop below the level of the top of the strip on the face of the cavity die roll as, otherwise, the trailing edge of the capsule cavity would have to lift the slugs in the magazine by a camming action as the cavity die roll rotates. In many instances, this type of action may occur to some extent without damage, but particularly with soft slugs, there is always a danger of breakage. Figure 14 shows the sealing action on the full depth cavity. The smooth surface seal roll 91 brings the upper plastic strip 92. down against the cutting out faces of the capsule cavity inserts and smoothly and uniformly cuts out the strips around the slugs. As shown in Figure 14, cavity A has the strip drawn down until it contacts the orifice 82 the bottom of the insert. In position B the the vacuum is released and the strip is permitted to draw up against the slug. In position C the sealing strip is pressed down against and sealed to the lower strip. A certain amount of air is usually trapped with the slug. The amount of air can be varied by changing the release point of the vacuum, but usually enough air is trapped so that the plastic strip lies loosely against the slug giving a smoother and evenly wrapped configuration to the capsule and preventing the appearance of a skin-tight, stretched appearance.

It tight wraps are desired, a small nick may be cut in one edge of the capsule-cavity inserts, so that a small hole is left in the seal line, which permits any trapped air to escape as the plastic strip draws itself against the slug and hardens.

The ejection and discharge of the finished capsules may be the same as in the previously described modification.

T-he piston and plug or the orifice ejection system may be used with either type of die roll-sealing roll system. Similarly, the details of the slug magazine for either modification may be interchanged.

Other modifications and minor changes in apparatus will suggest themselves to those skilled in the capsuletorming art. Such minor modifications and changes are part of our invention as set forth in the following claims.

We claim:

1. A method of forming plastic film covered precompacted powder-filled capsules which comprises, compacting a powder into long oval slugs, placing a plurality of said slugs in a vibratory feeder bowl, vibrating said bowl, thereby causing said slugs to feed serially axially, passing the slugs serially axially through a vibrating feed tube, feeding the slugs end-wise into a magazine, vibrating said magazine, by dropping gravity to a predominantly horizontally aligned position with a plurality of the sings in parallel oriented stacked relationship, dropping past clongated apertures permitting selective hand elignhig oi slugs, shaking out by vibration through said apertures misaligned slugs, collecting and re-using the shaken out slugs, and continuing to drop the stack of slugs until adjacent to the hereinafter reciter recesses, laying a first continuous strip of plastic sheet material over a plurality of capsule forming cavities in a cavity die roll, reducing the pressure within the cavities, thereby drawing the first strip down into the cavities to form a series of recesses, continuously passing said series of such recesses under the stack of slugs, dropping a slug at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving the slug in its associated recess from under the stack of slugs, warming a second continuous strip of plastic sheet material, placing said second strip in juxtaposition to said slug-containing recessed first strip, maintaining the reduced pressure within the cavities until just prior to the emplacement of the second strip, raising the pressure in the cavities, thereby releasing the first strip and permitting it to shrink against the slugs as the cavities approach a sealing position, sealing together and cutting out the portions of said strips surrounding each slug, re-applying a reduced pressure within the cavities to retain the capsules therein, pulling the net, consisting of the residual portions of the two strips, away from the capsules retained in the cavity die roll, ejecting the capsules from the cavities, and permitting the cut-out portions of the strips by the release of differential strains induced by the heating of the second strip, to adjust the capsules to a symmetrical final form.

2. A method for forming plastic film covered preconipacted powder-filled capsules which comprises, compacting a powder into slugs, pie-forming a series of recesses in a first continuous strip of plastic sheet material, stacking said slugs in contacting, oriented relationship, with the bottom slug supported on said strip, continuously passing said series of such recesses under said stack of said slugs, dropping a sing at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving the slug in its associated recess from under the stack of slugs, placing a second continuous strip of plastic sheet material in juxtaposition to said slug-containing recessed first strip, and sealing together and cutting out the portions of said strips surrounding each slug.

3. The method of claim 2 which comprises coating the sides of both the first and second continuousstrips of plastic sheet material which are to contact the slug and form the interior of the capsule with an inside coating material.

4. A method for forming plastic film covered precompacted powder-filled capsules which comprises, compacting a powder into long oval slugs, placing a plurality of said slugs in a vibratory feeder bowl, vibrating said bowl, thereby causing said slugs to feed serially axially, passing the slugs serially axially through a vibrating feed tube, feeding the slugs end-wise into a magazine, vibrating said magazine, dropping by gravity to a predominantly horizontally aligned position with a plurality of the slugs in parallel oriented stacked relationship, dropping past elongated apertures permitting selective hand aligning of the slugs, shaking out by vibration through said apertures this-aligned slugs, collecting and re-using the shaken out slugs, and continuing to drop the stack of slugs until adjacent to the hereinafter recited recesses, pre-forming a series of recesses in a first continuous strip of plastic sheet material, continuously passing said series of such recesses under a stack of said slugs, dropping a slug at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving the slug in its associated recess from under the stack of slugs placing a second continuous strip of plastic sheet material in juxtaposition to said slug-containing recessed first strip, and sealing together and cutting out the portions of said strips surrounding each slug.

5. A method for forming plastic film covered precompacted powder-filled capsules which comprises, compacting a powder into long oval slugs, placing a plurality of said slugs in a vibratory feeder bowl, vibrating said bowl, thereby causing said slugs to feed serially axially, passing the slugs serially axially through a vibrating feed tube, feeding the slugs end-wise into a magazine, vibrating said magazine, dropping by gravity to a predominantly horizontally aligned position with a plurality of the slugs in parallel oriented stacked relationship, dropping past elongated apertures permitting selective hand aligning of the slugs, shaking out by vibration through said apertures mis-aligned slugs, collecting and re-using the shaken out slugs, and continuing to drop the stack of slugs until adjacent to the hereinafter recited recesses, laying a first continuous strip of plastic sheet material over a plurality of capsule forming cavities in a cavity die roll, reducing the pressure within the cavities, thereby drawing the first strip down into the cavities to form a series of recesses, continuously passing said series of such recesses under a stack of said slugs, dropping a slug at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving the slug in its associated recess from under the stack of slugs, placing a second continuous strip of plastic sheet material in juxtaposition to said slug-containing recessed first strip, and sealing together and cutting out the portions of said strips surrounding each slug.

6. A method for forming plastic film covered precompacted powder-filled capsules which comprises, compacting a powder into slugs, laying a first continuous strip of plastic sheet material over a plurality of capsule forming cavities in a cavity die roll, reducing the pressure within the cavities, thereby drawing the first strip down into the cavities to form a series of recesses, stacking said slugs in contacting, oriented relationship, with the bottom slug supported on said strip, continuously passing said series of such recesses under said stack of said slugs, dropping a slug at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving the slug in its associated recess from under the stack of slugs, placing a second continuous strip of plastic sheet material in juxtaposition to said slugcontaining recessed first strip, maintaining the reduced pressure within the cavities until just prior to the emplacement of the second strip, raising the pressure in the cavities, thereby releasing the first strip and permitting it to shrink against the slugs as the cavities approach a sealing position, and sealing together and cutting out the portions of said strips surrounding each slug.

7. A method for forming plastic film covered precompacted powder-filled capsules which comprises, compacting a powder into slugs, laying a first continuous strip of plastic sheet material over a plurality of capsule forming cavities in a cavity die roll, reducing the pressure within the cavities, thereby drawing the first strip down into the cavities to form a series of recesses, continuously passing said series of such recesses under a stack of said slugs, dropping a slug at least partially into each recess as said recess passes under the stack of slugs, thereby positioning a slug in each recess, moving .the slug in its associated recess from under the stack of slugs, placing a second continuous strip of plastic sheet material in juxtaposition to said slug-containing recessed first strip, maintaining the reduced pressure within the cavities until just prior to the emplacement of the second strip, raising the pressure in the cavities, thereby releasing the first strip and permitting it to shrink against the slugs as the cavities approach a sealing position, sealing together and cutting out the portions of said strips surrounding each slug, reapplying a reduced pressure within the cavities to retain the capsules therein, pulling the net, consisting of the residual portions of the two strips, away from the capsules retained in the cavity die roll, and ejecting the capsules from the cavities.

8. The method of claim 7 in Which the capsules are ejected from the cavities by applying air pressure to cap sule ejector pistons, raising the pistons and plugs attached thereto and forcing the capsules out of the cavities by these plugs.

9. The method of claim 7 in which the ejected capsules are ejected into a moving stream of air and carried and tumbled by the moving stream of air.

10. An apparatus for forming plastic film covered circular cross-section pre-compacted powder-filled capsules which comprises a rotating die roll, a series or" cutting out rim surrounded capsule forming cavities in said die roll, means for supplying a first continuous strip of plastic sheet material and feeding said strip onto the surface of said die roll, means for coating the slug contacting side of the strip with an inert innocuous coating substance, a slug magazine above the die roll for feeding compacted powder slugs of approximately circular cross-section into strip-lined cavities in said die roll, a positionable slug retainer insertable into the channel in the magazine whereby the feeding of slugs through the magazine may be interrupted, apertures in the cover of said magazine to permit mis-aligned slugs to fall therethrough under the influence of vibration, means for collecting the fallen slugs for re-use, means for feeding slugs into the magazine comprising a bowl feeder, a vibrator for vibrating said feeder,

a loose mounting for the slug magazine, and a slug feeding tube slightly larger than the diameter of the slugs from said feeder to said magazine, means comprising a seal roll for supplying a second continuous strip of plastic sheet material and placing said second strip in juxtaposition to the slug containing first strip, means integral with said seal roll for maintaining the seal roll at temperature slightly elevated above the die roll temperature, means for coating the slug contacting side of second strip with an inert innocuous coating substance, means for rotating said rolls at the same'surface speed in contact with each other thereby sealing together and cutting out the portions of the two strips adjacent the slugs, a suction passage connected to the interior of each cavity in the die roll, a source of vacuum, valve means for connecting said passage to said source prior to the passage of the cavity under the slug magazine and maintaining said connection until just prior to the time at which the sealing together and cutting out occurs and releasing the vacuum during the sealing together and cutting out, thereby permitting the strips to more closely contact the strip, means for adjusting the vacuum release point, means for re-applying the vacuum in the cavities after the sealing and cutting out operation, thereby retaining the capsules in the cavities, means for stripping the residual net from the capsule containing die roll, means for ejecting the capsules from the die roll into a capsule receiving housing, and an air blast to pick up and convey the capsules to a desired location.

11. An apparatus for forming plastic film covered precompacted powder-filled capsules which comprises a retating die roll, a series of capsule forming cavities in said die roll, means for supplying a first continuous strip of plastic sheet material and feeding said strip onto the surface of said die roll, means for depressing said strip into said cavities, a slug magazine to support a stack of slugs in contacting, oriented relationship above the die roll with the bot-tom slug in contact with said strip for feeding compacted powder slugs into strip-lined cavities in said die roll, means for feeding slugs into said magazine and for vibrating said magazine, means comprising a seal roll for supplying a second continuous strip of plastic sheet material and placing said second strip in juxtaposition to the slug containing first strip, means for rotating said rolls at the same surface speed in contact with each other and means on the rolling surfaces of said rolls to seal together around the slugs and cut out from the strips the portions of the strips adjacent the slugs, thereby forming film covered pre-compacted powder filled capsules.

12. The apparatus of claim 11 in which the means for feeding the slugs into the magazine comprises a bowl feeder, a vibrator for vibrating said feeder, and a slug feeding tube slightly larger than the diameter of the slugs from said feeder to said magazine.

13. The apparatus of claim 12 which comprises a loose mounting for the slug magazine so that the magazine is vibrated by the bowl feeder acting through the slug feeding tube.

14. The apparatus of claim 11 in which the means for depressing the strip comprises a suction passage connected to the interior of the cavity, a source of vacuum, and valve means for connecting said passage to said source prior to the passage of the cavity under the slug magazine, said valve means including means for maintaining said connection until just prior to the time at which the sealing together and cutting out occurs, and releasing the vacuum during the sealing together and cutting out, thereby permitting the strips to more closely contact the slug.

15. The apparatus of claim 14 comprising means for adjusting the vacuum release point, whereby the degree of contact of the strips with the slug may be varied.

16. The apparatus of claim 14 comprising means for reapplying the vacuum in the cavities after the sealing and cutting out operation, thereby retaining the capsules in the cavities, and means for stripping the residual net from the capsule containing die roll.

17. The apparatus of claim 16 which comprises means.

for ejecting the capsules from the die roll into a capsule receiving housing, and an air blast to pick up and convey the capsules to a selected location.

18. An apparatus for forming plastic film covered circular cross-section pre-compacted powder-filled capsules which comprises a rotating die roll, in said die roll a series of capsule forming cavities of a depth less than the diameter of a slug plus twice the film thickness, a cutting out rim surrounding each cavity, means for supplying a first continuous strip of plastic sheet material and feeding said strip onto the surface of said die roll, means for depressing said strip into said cavities, a slug magazine to support a stack of slugs in contacting, oriented relationship above the die roll with the bottom slug in contact with said strip for feeding compacted powder slugs of approximately circular cross-section into strip-lined cavities in said die roll, means for feeding slugs into said magazine and for vibrating said magazine, means comprising a seal roll for supplying a second continuous strip of plastic sheet material and placing said second strip in juxtaposition to the slug containing first strip depressions in said seal roll, below the generally circular cylindrical surface of the roll, of a pattern to match the cavities in the die roll, and of a depth equal to at least that amount by which the maximum diameter of the slugs plus twice the film thickness exceeds the cavity depth, and means for rotating said rolls at the same surface speed in contact with each other thereby sealing together and cutting out the portions of the two strips adjacent the slugs.

19. The apparatus of claim 18 comprising a vacuum passage to each depression in the seal roll, and vacuum means, connectable to said passage, to draw the said second strip into said depression and into heat transfer relationship with that portion of the seal roll in the de pression.

20. An apparatus for forming plastic film covered circular cross-section pre-compacted powder-filled capsules which comprises a rotating die roll, in said die roll a series of capsule forming cavities of a depth equal to at least the maximum diameter of the slugs plus twice the film thickness, a cutting out rim surrounding each cavity, means for supplying a first continuous strip of plastic sheet material and feeding said strip onto the surface of said die roll, means for depressing said strip into said cavities, a slug magazine to support a stack of slugs in contacting, oriented relationship above the die roll with the bottom slug in con tact with said strip for feeding compacted powder slugs of approximately circular cross-section into strip-lined cavities in said die roll, means for feeding slugs into said magazine and for vibrating said magazine, means comprising a smooth cylindrical surface seal roll for supplying a second continuous strip of plastic sheet material and placing said second strip in juxtaposition to the slug-containing first strip and means for rotating said rolls at the same surface speed in contact with each other thereby sealing together and cutting out the portions of the two strips adjacent the slugs.

References Cited in the file of this patent UNITED STATES PATENTS 1,481,866 Heist Jan. 29, 1924 1,883,449 Andrews Oct. 18, 1932 1,895,899 Schaub Jan. 31, 1933 1,970,396 Scherer Aug. 14, 1934 2,083,617 Salfisberg June 15, 1937 2,180,966 Salfisberg Nov. 21, 1939 2,208,951 Tamassy July 23, 1940 2,420,983 Salfisberg May 20, 1947 2,513,852 Donofrio July 4, 1950 2,541,387 Salfisberg Feb. 13, 1951 2,546,059 Cloud Mar. 20, 1951 2,579,415 Carson Dec. 18, 1 951 2,597,986 Halstead May 27, 1952 2,602,942 Otto July 15, 1952 2,619,869 Stewart Dec. 2, 1952

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