US2799048A - Die roll for encapsulating machine - Google Patents

Description

3 Sheets-Sheet l ATTORNEY July 16, 1957 F. E. STIRN ETAL DIE ROLL FOR ENCAPSULATING MACHINE Filed Dec. 15, 1954 F|g.l.

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DIE ROLL FOR ENCAPSULATING MACHINE Filed Dec. 13., 1954 v 3 Sheets-Sheet 2 INVENTORS FRANK E. 5T/R/V ARTHUR .S. TAYLOR A TTOR/VEX July Filed Dec. 13, 1954 a H R a "a N {In 3 |.1

F. E. STIRN ETAL DIE ROLL FOR ENCAPSULATING MACHINE 3 Sheets-Sheet 3 INVENTORS Frank E. Stirn Arthur S. Tqylor ATTORNEY United States Patent DIE R'ULL FOR ENCAPSULATING MACHINE Frank E. Stirn, Monsey, and Arthur S. Taylor, Spring Valley, N. Y., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine Application December 13, 1954, Serial No. 474,801

4 Claims. (CI. 18-21) This invention relates to an improvement in a die roll for an encapsulating machine for the formation of soft plastic capsules from plastic stripmaterial, such as soft gelatin. The capsules may be filled withpowder or liquid or powder and liquid.

The present invention relates more particularly to a die roll in which a flexible foraminous material provides a portion of the bottom of the capsule forming cavity.

This application isa continuation-in-part ofour copending application Serial Number 399,130, filed Decemher 18, 1953, entitled Capsule Forming Die Roll, now Patent Number 2,697,317.

Methods of filling capsules are disclosed in said appli cation Serial Number 399,130 and in U. S. patents such as Patent 2,663,128, December 22, 1953', Frank E. Stirn and Arthur S. Taylor, Method and Machine for Making Capsules; and in our copending application Serial Number 164,426, filed May 26, 1950, entitled Method and Apparatus for Forming Combination-Filled Capsules. Other methods for filling the capsule shell may be used with the present die roll.

In the past, die rolls have usually been made: from a single engraved blank and as shown in patents to Cowley, 2,387,747 or Weckesser, 2,323,581, have frequently used holes in the bottom which were sealed by the plastic strip to control the application of the vacuum tothe interior of the capsule fonning cavity. As set forth and claimed inour copending application Serial Number 399,130, now Patent Number 2,697,317, air operated pistons and plugs fitting sufficiently loosely for air to pass between the plug and its retainer have also been used.

We have now found that particularly in small capsules, especially circular or elliptical capsules, it is convenient to have no moving parts and to have no openings of appreciable size in the interior of the capsule forming cavity. With the use of moving plugs there isalways the possibility of the capsule contents or plastic strip material getting between the plug and the plug retainer from which it must be removed to insure easy action. With orifices, such as shown in Cowley or Weckesser, the plastic strip material may, if thin, be partially drawn into the passages connecting with the bottom of the capsule forming cavities from which it can again be removedonly with difficulty. The use of such orifices causes trouble particularly in starting and stopping the machines, when the plastic strip material may be thinner than normal so that feather edges or threads of the strip material may be drawn into and clog the air passages. It has now been discovered that the cavity die roll may be assembled by using a flexible foraminous material such as felt in the bottom of the capsule forming cavities and thereby the use of moving mechanical parts or orifices in the bottom of the cavities is avoided. Further, by using a threaded hole the felt insert may be firmly retained and adjustably positioned so that the effective size of the capsule forming cavity may be adjusted by raising or lowering the height of the top of the felt insert.

Adjustment of the size of the capsule forming cavity by moving the flexible foraminous material permits less accurate machine work in manufacturing die rolls and markedly reduces their initial cost. Further, there. is more active surface through which air or an inert gas may pass to control the pressure within the capsule forming cavities and there are no passages of a size which are apt to be clogged by the capsule contents, be it liquid or powder. Furthermore, the flexible foraminous, material may be easily replaced or cleaned should it become necessary. The flexibility of the flexible foraminous material tends to prevent bridging of various materials which otherwise would tend to inhibit the passage of air therethrough. The machines are easier to start and stop and there is less trouble if, through an accident in technique, a capsule charge is inadvertently dropped into a capsule forming cavity which does not have a lining of plastic strip material.

Thinner and more delicate strips may be used with a flexible foraminous material forming the bottom of the capsule forming cavity. With the use of passages such as is shown by Cowley or Weckesser, a thin and delicate strip may be drawn into and clog the passages. With very small capsulestwhich desirably have a very thin wall of plastic strip material, the use of flexible foraminous material markedly facilitates commercial operation. Less maintenance is required and a unitary one-piece die roll may be constructed. The flexible foraminous material diffuses the vacuum over a greater-area and gives smoother and more effective gas flow control than would an open passage of equivalent gas passing capacity. These and other objects and advantages of our invention, appear in more detail in the following description of an embodiment thereof, and the accompanying drawings, which set forth by way of example certain embodiments of the invention covered by the appended claims:

Figure 1 is a capsule cavity insert for forming spherical capsules showing a hollow cavity insert retaining screw, with a flexible foraminous insert therein.

Figure 2 is a capsule cavity insert for spherical capsules showing a flexible foraminous bottom plug even with the bottom of the capsule forming cavity.

Figure 3 shows a capsule cavity insert for spherical capsules with a foraminous insert with said plug in a lower. position.

Figure 4 shows a sectional view through a capsule cavity insert similar to that shown in Figure 2.

Figure 5 shows a sectional view through a similar cavity in whichv the. flexible foraminous material is partially depressed in the tapped hole.

Figure 6 is. a sectional view of a capsule cavity insert retained in position by a hollow screw similar to that shown in Figure 1.

Figure 7 is a view of a capsule. forming cavity in which the upper surface of the flexible foraminous material is above the bottom of the capsule forming cavity and in which the die roll is of one-piece construction.

Figure 8 is a plan view of a round capsule forming cavity.

Figure 9 is a plan view of an elliptical capsule forming cavity, on a long, oval insert base.

Figure-10 is an elevation view in detail of a cavity die roll, showing the valve plates in connection therewith.

Figure 11" is a sectional view through the cavity die roll, showing certain features of its construction, and its relationship with the valve plates.

Whereas our die rolls may be used with any plastic material the strips-of which will seal to each other when out with a bluntedged cutter, our die rolls are particularly useful in conjuntion with a soft gelatin composition, such as is currently used in therapeutic capsules.

As shown in Figure 1, the capsule cavity insert'll is retained in position by an interiorly threaded hollow screw 12. The interior of this screw has therein a felt insert 13. The threaded hollow screw fastens into threads at the bottom of a slot 14 in the cavity die roll 15. The felt itself may be conveniently a wool felt such as is sold as S. A. E. #l and may be cut to a size to fit the threaded opening by a hollow tube such as a cork borer. When using capsule cavity inserts for built up die rolls, the capsule cavity inserts are individually formed. The rim thickness may be approximately that of the film upon which they work. From /2 to 1 /2 times the film thick ness is a useful operating range. The thickness of the bottom is preferably considerably greater for rigidity, but may be varied depending upon the materials of construction. The dimensions are not critical, and may vary over wide limits, depending upon the size and shape of capsules desired. The inserts may be of tool steel, or other hard material, so as to give a superior life to the finished cavity die roll. The insert receiving slots 14 may be slightly smaller than the size of the outside of the capsule cavity inserts, so that the capsule cavity inserts may be pressed therein and retained through the life of the cavity die roll. After the complete die roll is as semblcd, the top surface of the capsule cavity inserts may be ground so that each cutting out rim 16 is the same height, and a part of the cylinder surface of the roll. Accuracy is required in the construction as this rim cuts out the individual capsules by being forced against the seal roll, and variations or defects may give a defective cut-out.

As shown in Figure 2, instead of retaining the capsule cavity insert in the cavity die roll by a threaded hollow screw, it may be convenient to form a slot 14 in the cavity die roll slightly smaller than the capsule cavity insert 11 and seat the capsule cavity insert in the slot under pressure so that it is firmly retained as a press fit. The felt insert 13 is threaded into the tapped hole 24.

in Figure 3 is shown a capsule cavity insert which is similar to Figure 2, except that the felt insert 13 is lower in the tapped hole 24, to increase the capacity of the capsule forming cavity 20.

Figures 4, 5 and 7 are sectional views of the capsule cavity insert assemblies in which the felt insert is level with the bottom, below the bottom, and above the bottom of the interior of the capsule cavity insert, which thereby provides for adjustment in the volume of the capsule forming cavity, and thereby, in the capacity of the completed capsules.

Figures 4 to 7 show the plastic strip material 17 in place in the capsule cavity inserts as the strip is drawn down by vacuum during the filling operation.

Figure 6 shows a sectional view of the construction of the die roll shown in Figure l, with the plastic strip material drawn into the capsule forming cavity, ready to be filled with the capsule contents.

As is shown in Figure 7, the capsule forming cavity may be formed from a solid blank in which the surface of the cavity die roll 18 is cut down both interiorly and exteriorly of the cutting-out rim 19. In this construction the capsule forming cavity 20 is engraved into the face of the die roll. In a part of the bottom of the capsule forming cavity is a tapped hole 21 into which the felt plug 22 is screwed. From the bottom of the tapped hole the manifold passage 23 passes to suitable valving mechanisms to control the gaseous pressure within the capsule forming cavity in accordance with conventional practice.

The capsule cavity inserts may be either circular or elliptical. The ellipse may be cut on the capsule cavity insert with an ellipse cutting chuck. The hollow screws are particularly conveniently used in retaining elliptical inserts.

The, ratio of eccentricity, and the configuration may vary. Figure 8 shows a round capsule cavity insert 11, for spherical capsules. As shown in Figure 9, the capsule cavity insert 25 is long oval in shape, and has an elliptical cavity 26. The construction is otherwise the same.

The complete die roll itself may be of integral or builtup construction. In the particular modification shown in Figures 10 and 11, the cavity die roll consists of a cavity die roll blank 27, which is machined from a single piece of material. This'blank has a hub with an opening for an axle with a suitable means such as a keyway 28 for fastening the cavity die roll itself upon a shaft. Set screws or other fastening means may be used; or the wheel may be permitted to turn .upon this shaft if driven by a suitable means. The cavity die roll has, around its periphery, a series of capsule cavity inserts 11 which fit into insert slots 14 cut in the surface of the cavity die roll blank. The inserts may be any of the forms shown in the preceding figures, or engraved cavities as shown in Figure 7 may be used. The manifold passage 23 from the under side of the felt inserts connects to a valve seat surface 29 of the cavity die roll blank. Adjacent to this valve seat surface is the valve plate 30.

The valve plate 30 slides upon the valve seat surface of the cavity die roll. As shown in Figure 11, there is a valve plate on each side of the particular rolls here shown. These are symmetrical and their function the same. All cavities could be manifolded to a single side, if desired. The valve plates slide on the hub of the cavity die roll blank and against the face of the cavity die roll valve surface. Springs may be used to aid in positioning these plates, but normally the vacuum used during the operation of the machine is sufficient to hold these plates tightly against the surface of the cavity die roll valve seat surfaces.

As shown in Figure 10, two vacuum leads connect with the two vacuum chest portions of this plate. The vacuum connections are shown at 31 and 32, and the vacuum chests at 33 and 34, respectively. The vacuum chest 33 connects to a balancing chamber 35 so as to give a balanced action of the vacuum and to hold the plate smoothly against the surface of the cavity die roll throughout its entire periphery.

The first chest 33 draws a plastic strip material 17 into the capsule forming cavity 20 throughout the top of the arc of the cavity die roll. There is a gap 36 between the two vacuum chests, so that there is no vacuum acting on the strip at the time of formation of the seal. At the ejector point there is a pressure chest 37 connected to a pressure line 38. Air pressure acting through the felt insert ejects the formed capsules from the cavity die roll. In operation, the valve plate is prevented from rotating by a valve plate positioning bracket 39.

As will be obvious, the relative proportions of the capsule forming cavities may vary over a considerable range, depending upon the size of capsules which are to be produced. Whereas the present die roll is particularly adapted to an asymmetrical formation such as is described in the previously mentioned Stirn and Taylor patents, they may be used for the formation of capsules by symmetrical procedure such as illustrated in the Cowley or Weckesser patents previously mentioned.

Having described certain embodiments thereof, as our invention we claim:

1. A cavity die roll for forming soft plastic capsules from plastic strips which comprises a substantially cylindrical die roll blank having a plurality of slots in the periphery thereof, in each of said slots a capsule cavity insert having a serrated hole therethrough, a foraminous insert in said serratedhole, and air duct means extending from the lower side of said foraminous material to a valve face of said die roll.

2. A cavity die roll for forming soft plastic capsules from plastic strips which comprises a substantially cylindrical die roll having in its periphery a plurality of capsule forming cavities, and at least one serrated hole in the bottom of each of said cavities, a flexible foraminous insert adjustably positioned in each of said serrated holes,

and air duct means in said die roll from the lower side of said foraminous material to a valve face of said die roll.

3. A cavity die roll for forming soft plastic capsules from plastic strips which comprises a substantially cylindrical die roll having a plurality of slots in the periphery thereof, a capsule cavity insert having a tapped hole in each of said slots, and an adjustable flexible foraminous plug in each tapped hole whereby the volume of the capsule cavity insert may be varied, said die roll having air duct means extending from the lower side of said foraminous material to a valve face of said die roll.

4. A cavity die roll for forming soft plastic capsules from plastic strips which comprises a substantially cylindrical die roll having in its periphery a plurality of slots including a tapped hole at the bottom of each of said slots, a capsule cavity insert in each slot, an interiorly threaded hollow capsule cavity insert retaining screw passing through the bottom of said capsule cavity insert into the tapped hole in said die roll, said screws serving to retain said capsule cavity insert in said slot, and a flexible foraminous plug in the interiorly threaded hollow screw.

References Cited in the file of this patent UNITED STATES PATENTS 1,983,976 Garvey Dec. 11, l934 2,513,852 Donofn'o July 4, 1950 FOREIGN PATENTS 921,354 France Jan. 10, 1947

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