US2902802A - Encapsulating die roll system - Google Patents

Description

Sept. 8, 1959 sTlRN ETAL 2,902,802

ENCAPSULATING DIE ROLL SYSTEM Filed Dec. 24, 1956 1 2 Sheets-Sheet 1 INVENTOR. FRANK E. STI RN BY ARTHUR S. TAYLOR Sept. 8, 1959 F. E. STIRN ETAL ENCAPSULATING DIE ROLL SYSTEM 2 Sheets-Sheet 2 Filed Dec. 24, 1956 INVENTOR.

FRANK E. STIRN ARTHUR S. TAYLOR United States Patent" (3 ENCAPSULATING 'DIEROLL 'SYSTEM Frank Stirn,-Mnsey, and-Arthur S.'"Ta"ylor, Spring Valley, 'N.'Y.', assignors rtoiAmericane 1Cyanamid Company, New York, N .Y.', a corporationof Maine ApplieationiDecember 24; 1956, Serial No. 630,345

6 Claims. ..(Cl.. 53-1-28)? Thi's inventionrelates to a sealing roll system for use in forming and fillingsoft plastic capsules fromi'a plastic" strip,"and more particularly'to (l)'a die roll in which 'the cutting out' rims reciprocate'in. the die-roll, so as'to be flush during the filling step, and which rise to cut through: the plastic strips in the cutting out step, and (2) a flexible metal belt serving as the sealing member acting against cutting out rims on a die roll."

It is an object of this invention to'providea method,

and a machinefor practicing the method, whereby "a ma terial. to be encapsulated, which "may be a powder, a liquid, or a paste, is filled into cavities formed in a de formable' plastic strip,fwhi'ch strip is prevented 'from slidingover cutting out rims .during the forming, fi1l'ing,'.

and cutting out and sealing operations.

It is another object of this invention to provide" a cavity die roll iniwhich the vacuum under a plastic strip is maintained without excessive leakage.

It is a further. object of. this inventionuto provide a dieiroll which :gives uniform support to a plasticstrip between capsule forming cavitiesdui-ing the fillingopera tion'.

It is :a yetfurther object of .thi'sinventiontoprovide a cavity die roll which prevents theplastic "stripjfrom'walk-f ing on thesurfa'ce "of said "roll? It is an additional object of this inventionto provide a cavity die roll of'simplified'constructioni It is -a particular'objectof'thisiinvention to providea very*low a n gleof convergence betweenthe"cover'plastic strip and thelower cavitied plasticstripin'a capsule form ingoperation':

n isa specificobject'of'this inventiontwprovide a sea roll----system-*which eliminates-the necessity for accurate mating of cooperating sealing membersjand inwhich'the inherent flexibility of'tdesign expeditiously compensates for-"minon'dimensional errors in construction andflnis eliminates the necessityforhighprecision machine W 0I'k.'

Tlieart-has' long'used cooperatingmatingseal rolls in symmetricsystems for the manufacture of' capsules? Re cently asymn'ictri'c 'die' "roll' jsystems-have beenintroduced i in which a smooth'surface sealroll-eontactsa cavity die f roll-such as,"for example-, shownin'UESQPa'tent 2,663,128,

Stirn' and Taylor; -Metho'd"and'-'Machine'for Making Cap sules'; December-22; In such systemsnheangleof convergence between' 'the upper *and lower plastic strips;

has-been deterinine d 'by the diameters of the cavity die" roll-and theseal roll? A reduction in'this angle has re convergeneeris too'great,*the strip" tends-'towalkor weave" on the" surface'of the" cavity die *rol1;and the'seal "ofthe strips to each 'bther is impaired because the leading "edge and '--the? -trailing"edge of" the cutting-out rims. operateiat" a different"angle ofzittackthahth side edges? Obviously if the cutting --out rirn'- comes down symmetric and'p'erpen dic'ulai to' the fil'rii's -atzthe 'tinie 'of' sealingyand advan tageous seal is accomplishedr-With fixed edgesand r'ol'ls' this is not'possiblei Bu't largersizes of *rollshave been used: tonminimizer the anglemf -eonvergencei For con- 2,902,802 Patented. Sept. :8, 1959 ICC venience-in operatiomandto reduce the size ofthe maobtainedvwithsmaller rolls is desirable.

chine a system inwhich a smaller convergence angle is- Further the plastic w strip slides overthe surface of the cavity die. rolland over'the cutting outrims on that-- This problem has been common to all die rolls die roll. in which outstanding. cutting out rims are necessary for the cutting out andsealing operations.

These difiicultiesare largely obviated by the present machinein LWhich-theproblems introduced by the-out-- standing cutting out rims are obviated by using a hollow die roll havingin its surface a plurality of cavity slides:

havingcutting out rims thereon, which-rims are retracted so as to be flush with the surface of: the die'roll during-m;

the initial :plastic strip-positioning, cap'sule cavity forming,.and.capsule cavity filling operations, and in which" cutting :outrims. on the cavityslides 'areforced up through,

the plastic strips after the upperstrip" which covers the." capsule cavitiesis inplace. Such a die 'roll maybe 'useda in the present novelnmachine orusubstituted in conven--- tional encapsulation machines.

The. sealing member is a flexible belt, preferably of' metal. The belt is supported-on pulleys and is forced against-the seal roll by tension iii-the belt. Belt tension is used to hold the belt against the 'cutting=out'rims,'.-but yet not deform these cutting out n'ms or squash the plastic strips. One. of the support rollsrnay be positioned in rolling contact, throughthe belt, with the cutting out-rims? to give increased sealing-pressure at the point of final seal.

Because of the inherent flexibility of a belt, any minor variations in theworking surface of the cutting-out rims: due towear of these'rims and anyminordeviations from strict parallelism of: the-die roll and the belt support rolls as'well as any play in the cavity slides are inherently com--- be referredto as the upper and lower: plastic strip -with--- out further specifying its characteristics as such strips are" Well-known in the art. Substitutes may, of course, 'be used. fo'r gelatinand for the plasticizer, depending upon tern-=- p latu'le stabilityrequirements, edibility, costs, etc.-

The plastic strip maybe cast by a machine such as de k:

scribed in US. Patent 2,663,128, aforementioned, and the filliiig' of the formed capsule forming cavities may be as:

described in saidpatent or as described in U.S. Patent. 2,775,080, FJEfStirn et al.-, Method of Forming PoWder-. I

and-Liquid-Fille'd Capsules, dated December 25, l9S6,-or-

U.S'..".'Pa"tent 2,690,038fFJ'E. Stirn et al., Liquid-Filled Capsule "FormingMethod and Apparatus, September 28,

1954", "oras otherwise known to those skilled in theart.

The formation of the strip, filling of the formed capsule formingcavities, and.the pre-treatment of the strip, and

the"disposition of the'capsules after they are formed and'cut out are not here described as these steps are known to those skilled in the art and donot form novel elements of the'present invention.

Other-objects and" advantages ofthis invention will appear'from a description of certain specific embodiments thereof 'and' asshown in the accompanying drawings:.

Figure l is an elevation, in section, of the seal roll sys,-.

tem" showing the dieroll and seal belt. 7

Figure 2 is a section on line 22 of Figurel showing a cross section 'of the die roll system.

Figure'3 is a view'of a portion of the face of the die...

Figure 4 is a face view of the valve plate.

Figure 5 is a view of a modified construction, with a conventional cavity die roll, cooperating with a long sealing belt.

The size and shape of the desired capsule determine the size and shape of the capsule forming cavity and the cavity slide. The capsules may be round, elliptical, or long oval or other desired size and shape. The figures show a long oval form, which is particularly popular with the medical profession.

The plastic strips may be interiorly coated with a protective material to prevent the contents of the capsules from deleteriously aifecting the plastic strip. The die roll and seal belt contacting sides of the plastic strips may be coated with a thin layer of a lubricant such as deodorizedv kerosene, such as described in US. Patent 2,674,073, Taylor et al., Relieved Nonskid Seal Roll and Method of Use, April 6, 1954.

Lower plastic strip 11, supplied from a suitable source, is fed onto the surface of a hollow die roll 12, mounted on a support shaft 13, journalled in a main frame 14, by shaft bearings 15. The support shaft and hollow die roll are driven by the die roll drive gear 16 driven by suitable conventional means, which are not shown.

In the hollow die roll are a plurality of radial apertures 17 in each of which is a cavity slide 18 having at its outer end a capsule forming cavity surrounded by a cutting out rim 19. At the other end of the cavity slide is a cam surface 20 which slides on the cam 21 and is held against the cam by the slide return springs 22. A small toe on the front and rear of the slide near the cam surface furnishes a bearing area for this spring.

The cavity slide is supported by the cam so that the cutting out rim is flush with the outer cylindrical surface of the hollow die roll as the lower strip is fed onto that surface, and as the strip is drawn into the capsule forming cavity in the end of the cavity slide by vacuum acting through the slide gas orifice 23, and the slide gas passage 24, which in turn are connected to the die roll manifold 25, which extends to the valve plate face 26 of the die roll.

Resting against the valve plate face of the die roll, and held in position thereagainst by vacuum is the valve plate 27. In this valve plate is a vacuum chest 28, the lower portion of which forms a balancing chest to aid in holding the valve plate against the valve plate face of the die roll, in which valve chest the vacuum is introduced by a vacuum lead 29, leading to a conventional vacuum source. Also in this valve plate is an atmospheric chest 30 vented to the atmosphere by an atmospheric vent 31,

to permit atmospheric pressure to act in the capsule forming cavity in the cavity slide at the time of seal as is later described. Also in the valve plate is a gas pressure chest 32 in which pressure is maintained by a gas pressure lead 33 leading to an external gas pressure source, not shown, which gas pressure is used for ejecting the capsule as is later described. The gas supplied to the gas pressure chest may be heated, as described in US. Patent 2,697,314 Stirn et al., Heating Die Roll, December 21, 1954, to maintain the die roll and cavity slides at a desired temperature.

As the die roll rotates, vacuum acting through the vacuum chest, die roll manifold, slide gas passage, and slide gas orifice reduces the pressure under the lower plastic strip 11 and draws the plastic strip down into the cavity slides, as shown at cavity slides U, V, W, and X, thus forming strip-lined cavities. The strip lies flat on the face of the seal roll. With raised cutting out rims, air can leak into the system adjacent to the rims, and greater vacuum capacity is required to allow for such leakage. With the present system there are no raised rims and leakage is minimized.

The strip-lined cavities are filled with the material to be encapsulated by a filling head 34. This filling head may be one of those described in the aforesaid US. Patbelt 39, which seal belt runs over an upper seal belt support roll 40, which in turn is journalled in the upper support roll bearings 41 and positioned in the frame by the upper bearing positioning screws 42. The tension in the seal belt is controlled by adjusting the roll position by these screws. The belt supported upper plastic strip is brought down to and in contact with the lower plastic strip containing the filled capsule forming cavities.

In as much as this belt is fiat before it reaches the point of tangency, the upper plastic strip is a plane, and the angle of convergence of the two strips is determined solely by the single die roll. Thus the angle of convergence is markedly less than would be the case with two rolls, all convergence problems are associated with only the one lower strip. Additionally, there are no raised cutting out. rims at the time of convergence, and problems associated therewith are deferred until the strips are more firmly positioned between the seal belt and the die roll.

Just before the upper plastic strip covers the capsule forming cavities in the lower plastic strip, the die roll manifold passes from contact with the vacuum chest to contact with the atmospheric chest in the valve plate, which permits the natural elasticity of the lower plastic strip to cause the strip to start to rise and thus diminish the volume in the capsule forming cavity in the lower plastic striy. The angular position of the valve plate is such that all excess air in each capsule forming cavity escapes just as the upper plastic strip comes in contact with the lower plastic strip and closes 01f communication with the outside air. Any minor variations in quantity of fill caused by mechanical variations in the sizes of the various parts is compensated at this point, as the capsule contents are so much more viscous than air that the contents will not escape at the bite of the roll, but only the air will escape, thus giving completely filled capsules without trapped air bubbles.

The two plastic strips are firmly held between the face of the die roll and the seal belt. This prevents loss of capsule contents, or sliding of the strips during the sealing and cutting out steps. Moreover, the strips are in contact and well supported at the time of cut out and seal, so that the entire periphery is sealed and cut out simultaneously so there is no leading or trailing edge, with associated problems.

As the die roll rotates the cam surface of the cavity slide slides on the cam 21 which is held against rotation by the cam holding plate 35 which in turn is positioned by the cam plate positioning shaft 36 which causes the cam to remain stationary on the cam bearings 37 as the support shaft 13 rotates. The cavity slides are raised by the cam as they pass through positions D, E, and F to a final height at position G so that the cutting out rim is forced up through the lower and upper plastic strips. As the cutting out rim passes through the two plastic strips, that portion of each of the plastic strips which surround the material being encapsulated are cut out and sealed to each other. Because of the plastic flow and sealing characteristics of the plastic strip the separate cut outs are joined thus forming the capsules, and leaving behind the perforated strips or web. The lower seal belt support roll 43 journalled in the lower support roll bearings 44 is positioned by the lower bearing positioning screws 45 so as to hold the seal belt against the cutting out rims and thus insure perfect cutting out.

This causes not only the flexible pressure from tension in the belt but positive positioned pressure from the lower support roll to function to insure the cut out.

.The cut out plastic; s tripsare then separated from thus formed capsules, which capsules are still retained in the cavity slides. "Conveniently the cutting outstrip may be held against the die roll during the removal of the capsules.

The upper plastic strip is advantageously at a slightly warmer temperature than the lower plastic strip so that the seal line between the two portions of each capsule is caused to become equatorially adjusted, by the warm portion from the upper strip stretching, and the cooler portion from the lower strip shrinking, such as is described inlthe aforesaid Patent 2,663,128.

The temperature adjustment is conveniently obtained by positioning an upper seal roll heating plate 46 against the upper seal belt support roll 40. A heating plate heating element 47 is incorporated in the upper seal roll heating :plate, which may conveniently be an electric resistance element, and the energy input is controlled by a :heating' .plate thermostat 48; The heater leads 49 and the thermostat leads 50 are fastened to a conventional control system, and energy source.

As the die roll rotates the capsules are ejected into the capsule receiving shield 51. The ejection is' in part caused by gas pressure through the pressure chest 32, acting through'the die roll manifold 25, slide gas passage .24 and slide gas orifice 23. The ejection is aided by a rotating stripper 52 which is a flexible bladed element h'aving blades of soft rubber or flexible cloth, or brush :bristles,'wh:ich aids in picking up the capsules and knocking them out of the capsule forming cavity in the cavity slide into the capsule receiving shield. As the capsules fall :to the lower portion of the shield, they are picked up by conveyor air blastj53 and blown through a capsule conveyor 54 for further processing. The residual web 'is pulled off by conventional means at the web take off 55, and recovered for reuse, or otherwise disposed of. i Modifications As will be obvious many variations can be made in the machine within the scope of the present invention. For example, the die rolls and the support rolls are conveniently of brass to insure high heat conductivity and ease of manufacture, and the cutting out slides are conveniently of steel for hardness, while the sealing belt itself is conveniently of stainless steel for both corrosion resistance and strength although other flexible durable materials may he used. Other materials of construction may be used. The bearing journals and support systems may be modified within wide limits. For instance the die roll may be journalled on a fixed shaft. Preferably the cam and die roll are supported and positioned by cantilever shafts, so that the front surface of the roll is open to the operator for ease in inspection and in threading during starting up and shutting down operations.

As shown in Figure 3 the die roll may contain four rows of cavity slides but, of course, any convenient number may be used. Similarly, the die roll is shown with 24 cavity slides in a peripheral row. A larger number is conveniently used as a larger number renders the sides of adjacent slides more nearly parallel, and reduces web losses. Less than 24 would be more convenient for small runs, or experimental use.

As shown in Figure 5 a conventional raised rim cavity die roll 56 may be used in conjunction with a seal belt 60 with the many advantages accruing from the reduced angle of convergency, and the flexibility of a seal belt as contrasted 'With a solid seal roll. As shown in Figure 5, the upper belt support roll 57 may be fixed in position, with an adjustable lower support roll 58, the position of which is controlled by positioning screws 59. This relationship with the seal roll permits additional flexibility of the seal belt. Because the lower support roll is not in contact through the belt with the cutting out rims on the die roll, the problems of uneven wear, or minor mechanical variations in construction are well tolerated.

6 The tension in the seal belt is adequate to insure adequate out out.

Theoretically, only the cutting out rim need rise during the cutting out and sealing step. Using a die roll in which only the rim raises has the theoretical advantage of leaving the capsule forming cavity volume constant, but introduces complications in design because of a fixed plug in a moving cylinder, which in the space available causes construction problems. Also important'is the desirability of reducing interior moving parts which can become clogged up with strip fragments. The use of solid slide inserts simplifies such construction.

Whereas air pressure is normally adequate for ejection of the capsule, positive piston action of the type shown in Patent 2,775,080 may be used in each slide. With thin plastic strip, the strip may tend to be drawn into the slide gas orifice. The use of felt inserts, such as described in our copending application Serial No. 474,801, Die Roll for Encapsulating Machine filed December 13, 1954, now US. Patent No. 2,799,048, in the gas orifice controls the plastic strip, even if very thin.

The retraction of the slides in the die roll may be accomplished by'cam action instead of springs, or the cavity slides may be retracted by a magnetizedcam, such as described in US. Patent 2,775,084, 'Stirn et al., Apparatus for FillingPowder in Capsules, December 25, 1956. Similarly the valve plate may use springs or magnetic inserts to aid in holding it against the valve face of the die roll, or other shapes of valve surfaces may be used.

Other modifications of the present novel die roll and seal belt system are within the scope of the following claims.

We claim:

*1. A cavity die roll for forming soft plastic capsules from plastic strip which comprises: a hollow die roll having a series of apertures extending from the Working face into the hollow interior thereof, means for rotating said die roll, a cavity slide having a capsule forming cavity and (a cutting out rim .at the outer end and a cam means at the inner end in each aperture, and a stationary cam, acting on the cam means of said cavity slide, of such configuration that the slides are positioned with the cutting out rim about even with the surface of the die roll during a loading portion of a capsule forming cycle, and with the cutting out rims raised against a sealin means during a cutting out portion of capsule forming cycle.

2. A cavity die roll for forming soft plastic capsules from plastic strip which comprises: a hollow die roll having a series of apertures extending from the working face into the hollow interior thereof, a valve plate face on said die roll, a die roll manifold from the valve plate face to said apertures, means for rotating said die roll, a cavity slide having a capsule forming cavity and a cutting out rim at the outer end and a cam means at the inner end in each aperture, said slide also having a slide gas passage in cooperating relationship with said die roll manifold, and a slide gas orifice opening into the capsule fonning cavity in said cavity slide, a stationary cam, acting on the cam means of said cavity slide, of such c0nfiguration that the slides are positioned with the cutting out rim about even with the surface of the die roll during a loading portion of a capsule forming cycle, and with the cutting out rims raised against a sealing means during a cutting out portion of capsule forming cycle, a valve plate positioned against the valve plate surface of said die roll having therein a vacuum chest, tan atmospheric pressure chest, and a pressure chest, in such angular position as to draw a plastic strip into the capsule forming cavity and hold the strip in the cavity during a loading cycle, release the strip in time to eject surplus air before a cover strip is juxtapositioned, and eject the capsule after its formation, and a vacuum lead, an atmospheric vent, and a pressure lead, respectively, to said chests.

3. A sealing roll system for forming soft plastic capsules from plastic strip which comprises: a hollow die roll having a series of apertures extending from the working face into the hollow interior thereof, means for rotating said die roll, a cavity slide having a capsule forming cavity and a cutting out rim at the outer end and a cam means at the inner end in each aperture, a stationary cam, acting on the cam means of said cavity slide, of such configuration that the slides are positioned with the cutting out rim about even with the surface of the die roll during a loading portion of a capsule forming cycle, and with the cutting out rims raised during a cutting out portion of capsule forming cycle, supporting rolls for a flexible belt, and a flexible belt on said pulleys, in cooperative relationship with said die roll, so as to retain two plastic strips therebetween, and cooperate with said cutting out rims to cut out capsules from the plastic strips.

4. A sealing roll system for forming soft plastic capsules from plastic strip which comprises: a hollow die roll having a series of apertures extending from the working face into the hollow interior thereof, a valve plate face on said die roll, a die roll manifold from the valve plate face to said apertures, means for rotating said die roll, a cavity slide having a capsule formin cavity and a cutting out rim at the outer end and a cam means at the inner end in each aperture, said slide also having a slide gas passage in cooperating relationship with said die roll manifold, and a slide gas orifice opening into the capsule forming cavity in said cavity slide, a stationary cam acting on the cam means of said cavity slide of such configuration that the slides are positioned with the cutting out n'm about even with the surface of the die roll during a loading portion of a capsule forming cycle, and with the cutting out rims raised during a cutting out portion of a capsule forming cycle, a valve plate positioned against the valve plate surface of said die roll having therein a vacuum chest, an atmospheric pressure chest, and a pressure chest, in such angular position as to draw a plastic strip into the capsule forming cavity and hold the strip in the cavity during a loadin cycle, release the strip in time to eject surplus air before a cover strip is juxtapositioned, and eject the capsule after its formation, a vacuum lead, an atmospheric vent, and a pressure lead, respectively, to said chests.

5. A sealing roll system for forming soft plastic capsules from plastic strip which comprises: a cavity die roll, having capsule forming cavities therein, radially movable cutting out rims around said capsule forming cavities, cam means to position the cutting out rims about even with the surface of the cavity die roll when the plastic strip is supplied to the face of the cavity die roll and to force said rims through plastic strip layers during cut out and sealing, a flexible metal belt positioned upon and in cutting out relationship with said rims during a cutting out and sealing portion of the travel of said die roll, and support rolls for said belt, at least one of which is adjustable to maintain tension in said belt.

6. The method of forming soft gelatin capsules which comprises: supplying a soft gelatin strip to the face of a die roll, forming capsule forming cavities by localized application of subatrnospheric pressure to areas on one side of said strip, filling the thus formed cavities with the material being encapsulated, tangentially feeding a second soft gelatin strip into contact with the first strip, retaining the two strips together by pressure applied over the entire contacting areas of said strips, applying a cutting out and sealing pressure around the peripheries of the filled cavities, while maintaining the holding pressure over the remainder of the contacting areas, to retain the strips in position during the application of cutting out and sealing pressure, and separating the thus formed capsules from the remainder of the strips.

References Cited in the file of this patent UNITED STATES PATENTS 1,970,396 Scherer Aug. 14, 1934 2,387,747 Cowley Oct. 30, 1945 2,546,059 Cloud Mar. 20, 1951 2,621,740 Shanley Dec. 16, 1952

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