US 3508678 A
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April 28, 1970 R J, GRAHAM ETAL 3,508,678
LOCKING CAPSULE Filed April 29, 1968 www wmw vh m mw T w45 T ID d A Mg n mi.. LW
United States Patent O ABSTRACT OF THE DISCLOSURE An economical locking capsule is provided having telescopically joinable cap and body parts adapted to be .joined together in a mechanical part-lock position and also, when more fully joined, in a fully locked position. The capsule, for packaging of medicaments and the like, is produced by the dip-molding technic on conventional automatic machinery and can be printed, filled, etc., using standard equipment.
SUMMARY AND DETAILED DESCRIPTION This invention relates to hard shell locking capsules of the type having a cap part and a body part adapted to be telescopically joined together to provide a container for substances such as pharmaceutical preparations intended for oral administration. More particularly, the invention relates to capsules of the kind described which can be manufactured, printed, filled and joined on modern high-production machinery and can be locked in the closed position, as desired, in a partial mechanical lock or in a more completely joined solid mechanical lock.
The conventional locking pharmaceutical capsules consist of a tubular or cylindrical cap part closed at one end with the opposite end open to telescopically receive a closely tting body part of like conformation having contacting inner surfaces which provide a locking action to prevent separation of the cap and body parts. In general, the known types of locking capsules are constructed to provide both a temporary lock (sometimes referred to as a semi-lock or pre-lock) when partly joined and a more secure lock when more fully joined. One such type of capsule, for example, is known from British patent specification No. 1,108,629 and Italian Patent No. 789,324. The prior art locking capsules have in general been satisfactory but some types have occasionally malfunctioned or failed from time to time in finishing, distribution, etc. In particular, the cap and body parts have sometimes tended to pop apart when joined on the production line; also, empty capsules in the pre-lock position prior to filling or subsequently, as in shipment to the customer, have sometimes pulled apart especially in a case where the cap has been insufficiently advanced onto the body. Also, capsules in the fully locked position have sometimes been known to pull apart and become separated due to severe vibration. Capsules of the friction lock type, that is capsules locked with the capsule walls under distortion, have been known to crack and fail, especially under excessive drying conditions as when filled with hygroscopic powders or other desiccating substances. The failures are not uncommon, especially during the printing operation using equipment which calls for precise length control of the pre-lock caspule. Separation failures are also likely to occur during the iilling steps, particularly where, as in standard machinery, the capsules are delivered from the supply hopper by oscillatory movements tending to cause the capsule parts to separate. A separated part undesirably can cause the magazine tube to be blocked, or a free cap, for instance,
can seat on a joined capsule body and form a doublecap which may jam the rectifying mechanism. Also, the loose part can crowd the filling ring chamber so that the intended body part does not seat properly in the lilling ring. As will be appreciated, each malfunction constitutes an economic loss whether of production time, during finishing, distribution, etc.
It is therefore an object of the present invention to provide a locking capsule of a novel type having an improved pre-lock construction for optimum performance during finishing, distribution, etc.
It is also an object of the invention to provide an improved capsule having cooperating elements for the partial and complete locking of the body and cap parts.
Still another object of the invention is to provide an improved capsule having pre-lock means assuring the partial joining of the capsule parts in a constant pre-determined len-gth.
Yet another object of the invention is to provide prelock means for capsules which prevents or minimizes the occurrence of popping apart of the capsule parts as they are being assembled.
Other objects, features and advantages of the invention will be seen in the following specification with reference to the accompanying drawings in which:
FIGURE l is a side view of an assembled capsule according to the invention;
FIGURE 2 is a section taken on axis line 2-2 of FIG- URE 1, of the upper part of a capsule of the invention in a full lock position;
FIGURE 3 is a similar view in the pre-locked or partly closed position;
FIGURE 4 is a transverse section of a capsule taken on line 4 4 of FIGURE l;
FIGURE 5 is a plan view in section of the indented pre-lock contour of the cap mold pin, the pin contour being covered over with a capsule shell coating;
FIGURE 5a is a section of the pre-lock position of a capsule shown in matching contact according to the invention with the groove of a capsule body;
FIGURE 6 is an elevational view of the cap pin contour represented in FIGURE 5; and
FIGURES 7a, 7b and 7c are sectional views illustrating the stepwise migration of the capsule liquid onto the shaped contours of a capsule mold pin as the pin is dipped increasingly deeper into the capsule liquid.
Referring to FIGURE l, the capsule of the invention 10 includes a cap 11 and a body 12 with closed ends 13 and 14, the parts being readily molded, stripped, etc., on standard capsule-making machinery and assembled easily, as desired, in either locked or semi-locked position. The cap 11 in a prefered form has a circumferential groove 15 or constriction, in a plane normal to the axis of the cap and body. The cap includes a cap end 18 with a suitable opening and a capsule indent 24.
The cap 11, in greater detail as seen in FIGURES 2 and 3, has an inner wall 16 and an outer wall 17. On the inner wall 16, opposite the groove 15 on the outer wall 17, is a circumferential ridge 19. The ridge 19 has a generally triangular cross-section defined on the inner surface by bevels 20 and 21 meeting at the apex 22. The closed end 13 is preferably rounded or hemispherical but the shape is not critical. It desired, the cap end can have other shapes. The inner cap wall 16 proceeding from the open end 18 to the line 23, which is the shoulder line, has a slight narrowing diametral taper of the order of 0.010 inch per inch exclusive of ridge 19 and indent means 24. In 'FIGURE 2 the cap and body parts are shown in the fully locked position Whereas in FIGURE 3 the cap and body parts are shown in partly closed or pre-locked position with the open end of the body advanced towards the leading bevel 20 of ridge 19. The body has a groove 19a which matches the ridge 19. Groove 19a has a leading bevel 20a and a trailing bevel 21a which join at apex 22a. In FIGURE 2, as indicated, the cap and body have been pressed together from the partly closed pre-locked or semi-locked position into the fully closed, locked position` In the latter position ridge 19 and body groove 19a are in a matching lit or mechanical it as distinguished from a friction iit, with their respective bevels and apexes in close conformity. In this position the open body end has advanced into the cap to a point near or preferably just beyond the shoulder line 23. The body like the cap is tapered in the same degree and in the direction from its open end to its closed end. The body taper and the body dimensions are such as to provide an ample entrance of the body into the cap. The body taper and the body dimensions in relation to the taper and dimensions of the cap also are such as to provide a relatively distortion-free fit in the pre-locked position shown in FIGURE 3; the fit between adjacent Wall surfaces of the cap and body advantageously permits the passage of air. Also, in this position the bevels 20a and 21a and the apex 22a are in close conformity with the indent flat 24a (FIGURES 5a and 6) and the respective indent slopes 24h. The pre-locked lit in the area of the indent 24 is a mechanical tit as distinguished from a friction lit. It is substantially distortion-free; the principal points of contact of the capsule indent 24 with the body groove 19a are at the edges 24d between the indent at 24a and indent slopes 24h. This construction being other than a compression lit, makes for increased passage means or air vent means 24e so as to permit the escape of compressed air contained within the capsule occasioned, for example, by the sudden joining of the body and cap parts into locked position. Thus, the release of air advantageously avoids any tendency of the cap and body to pop apart. Also, the particular constmction of the body groove bevels in relation to the at and slopes of the capsule indent 24 desirably provides a useful centering action so that the axial engagement of the body part with respect to the cap (i.e., the assembled capsule length) is at all times constant. The mentioned construction unexpectedly provides performance characteristics (in joining, separation, printing, filling, etc.) which are unexcelled by comparison with any prior art capsule heretofore produced. Thus, there is almost no tendency under the conditions obtaining in capsule manufacture for the pre-locked capsule parts in accordance with the invention to become separated inadvertently or to become joined together farther than intended. While the lit between the body groove and the capsule indent is substantially distortion-free, nevertheless there preferably should be a slight pressure generated at the points of contact sufcient to prevent any substantial or excessive rotatioinal movement of the cap and body parts with respect to each other.
It has been found according to the invention that the dimensions and contour of the capsule indent are a critical feature. In particular, the indent slopes 24b must for purposes of the invention be at a relatively low angle. This is required, in respect to the dip-molding method, in order to avoid the excessive formation of air bubbles in the freshly formed capsule wall. Thus, the slopes 24b in relation to the flat 24a (shown in FIGURE 5 as angle A and angle B) should form an angle of about 8-12". An angle of about 10 is preferred whereas slope angles substantially more than 12 are associated with the formation of excessive numbers of bubbles in the capsule wall portion adhering to the surfaces of the indent slopes and adjacent portions of the indent at 24a. FIGURES 7a, 7b and 7c illustrate how the capsule making fluid moves in relation to an excessively angular pin contour as the pin 25 is being dipped into the capsule liquid. In FIGURE 7a the capsule liquid 26 is rising upward along the pin and is entering the concavity of the pin mold indent. In FIGURE 7b the liquid has moved farther past the corner formed by the indent slope and the indent flat without actually wetting the corner so that the air bubble 27 is formed, In FIGURE '7c the capsule liquid 26 has moved higher across the capsule indent contour Without contacting the innermost corner portions of the contour thereby causing air bubbles 27 in these portions. Subsequently in the molding process while the pin bars are being transported, rotated, subjected to the drying cycle, etc., the air bubbles formed are believed to merge with the liquid film 26 and to migrate in the film until the film sets up and solidilies, whereupon the air bubbles 27 are physically trapped within the capsule wall and particularly with the wall of the capsule indent 24. Such air bubbles tend to cause an undesirable weakness of the capsule. In extreme cases, bubble formation results in formation of holes in the capsule.
The capsule indent 24 of the capsules of the invention must also have a relatively long iiat 24a between the indent slopes 24h. In general, a longer flat is associated with fewer, or smaller, air bubbles. It is found that in this regard the length of the indent flat separating slopes 2411 should be greater than about .010 inch and preferably about .020 inch; the width is of the same order and is not particularly critical, The depth of the capsule indent should be about .004 to .005 inch. Shallower capsule indents are less desirable since they give a relatively weak pre-lock, that is, they sometimes fail to properly locate the body groove for the pre-locked position. On the other hand, where this dimension is deeper the pre-lock tends to be excessive. The number of indents 24 in the capsule is not critical. Two or more indents with maximum circumferential spacing are preferred, as shown in the drawing. In general, the ridge and groove dimensions for the cap and body part, in particular for No. l capsules, are like those specified in the above-mentioned British and Italian patent specifications.
While gelatin of pharmaceutical grade is a preferred material for the manufacture of the capsules of the invention, other materials having like properties can be substituted in whole or in part for gelatin. It is conventional for capsule mold pins to be made of high-grade stainless steel, and it will be understood that the contour of the mold pins used for making the capsule parts of the invention can be suitably formed by any conventional means such as milling, grinding or the like. It will also be understood that the dip-molding process confers the contour of the pin precisely to the inner surface of the molded capsule part. In this respect the capsule cap parts of the invention which include the ridge 19 and the capsule indent 24 can be readily stripped from the `mold pins without difficulty or damage to the capsule part. In the preferred embodiments shown in the drawing the capsule ridge 19 is shown as a continuous circumferential ridge. Other equivalent ridge shapes can also be used. For example, the ridge 19 does not need to be continuous but can comprise spaced discontinuous ridge portions, if desired, separated by wall Iportions having the same circumferential contour or taper as the greater part of the cap.
While the invention in locking capsules has been described in detail in the foregoing specification, considerable variation in such detail can be made, as will be appreciated by those skilled in the art, without departing from the spirit of the invention.
1. A hard shell gelatin pharmaceutical capsule having a cylindrical, telescopically joinable, coaxial cap and body each having a side Wall, an open end and a closed end,
the cap side wall having an inner surface and an outer surface, and also having an axially elongated indent means and a circumferentially extending ridge means extending radially inwardly from the inner surface of the cap wall,
the body side wall having a circumferentially extending groove matching the ridge,
the indent means including two indent slopes separated by an indent at, the slopes in relation to the flat being at an angle of about 8-12" and the at separating the slopes by a distance greater than about .010 inch,
the capsule cap and body being adapted to be controllably joined together in a semi-lock and also being adapted to be joined together in a full lock located at a pre-determined position of more complete joining beyond the position of semi-lock,
the said full lock being provided by matching contact of the body groove with the cap ridge means,
the said semi-lock being provided by matching contact of the body groove with the cap wall indent means, said indent means being axially spaced apart from the ridge means at a suicient distance to accommodate entry of the body into the cap to the semi-lock.
2. A capsule according to claim 1 wherein the semilock is a mechanical lock.
3. A capsule according to claim 1 wherein the body groove and the indent means in the semi-lock position are substantially distortion-free and the matching contact is sutiicient to prevent random change of position with respect to relative rotation of the cap and body parts.
`4. A capsule according to claim 1 wherein the matching contact between the body groove and indent means in the semi-lock position defines air vent means for release of compression generated by joining of the cap and body parts.
5. A capsule according to claim 1 wherein the indent means comprises a plurality`of indents spaced substantially at equal distance on the cap wall circumference.
6. A capsule according to claim 1 wherein the indent means comprises two diametrically opposed indents.
7. A capsule according to claim 1 wherein the indent means includes indent slopes merging with an indent tiat, the slopes and at extending inward from the cap wall for a distance suicient to bear upon the body groove in the semi-lock position.
8. A capsule according to claim 7 wherein the depth of the indent means is about .004-.005 inch.
9. A capsule according to claim 7 wherein the angle between the indent slopes and the at is about 10, and the length of the indent flat is about .020 inch.
10. A capsule according to claim 9 wherein the depth of the indent means is about .004-.005 inch.
11. A hard shell gelatin pharmaceutical capsule having a cylindrical, telescopically joinable, coaxial cap and body each having a side wall, an open end and a closed end,
the cap side wall having an inner surface and an outer surface, and also having two opposing axially elongated indent means and a circumferentially extending ridge means extending radially inwardly from the inner surface of the cap wall,
the body side wall having a circumferentially extending groove matching the ridge, each indent means including two indent slopes separated by an indent flat, the slopes in relation to the at being at an angle of about 8-12" and the ilat separating the slopes by a distance greater than about .010 inch, the capsule cap and body being adapted to be controllably joined together in a partial lock and also being adapted to be joined together to provide a full lock located at a position of more complete joining beyond the position of partial lock, the said full lock being provided by matching contact of the body groove with the cap ridge means,
the said partial lock being provided by matching contact of the body groove with the two opposing cap wall indent means, said indent means being axially spaced apart from the ridge means at a predetermined distance to accommodate partial entry of the body into the cap as a partial lock when the body groove is in contact with the indent means.
References Cited UNITED STATES PATENTS 643,005 2/1900 Record 220-60 1,134,427 4/1915 Ullrich 220-60 2,104,540 1/1938 Hoffman 220-60 X 2,718,980 9/1955 Strom 220-60 2,950,813 8/1960 Koones 220--44 X 3,399,803 9/1968 Oglevee et al. 220-60 JOSEPH R. LECLAIR, Primary Examiner I. R. GARRETT, Assistant Examiner #(ggf UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3.508.678 Dated April 28, 1970 Inventor(s) Richard J. Graham, Oscar B. Noren and Ralph E. Mottin It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 2, line 7, correct "during finishing, distribution, etc." to read "capsule material, medicament, etc."
Column 2, line 52, correct the spelling of "preferred".
Column 4, line l2, correct "with" to read "within".
SIGNEII AN; HEME!) SEP 8 19m ISEAL) Attest:
Edward Ma metall. Irl
nesting Officer WLLLIAM E. SGHUYLER, Ja.
Commissioner ot Patents 1