Locking Capsule

Abstract

A locking capsule is provided for packaging unit doses of physiologically active agents, said capsule having a body portion and a cap portion which are adapted to be telescopically joined together in a frictionally engaged pre-locking position prior to the filling thereof and to be fully telescopically joined together in a mechanically locked position when filled.

Description

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to two-piece hard shell capsules one piece thereof comprising the body portion and the other piece the cap portion, said two pieces being telescopically joined together. More particularly this invention relates to a two-piece hard shell locking capsule in which the body portion can be partially telescoped into the cap portion at which point a friction pre-lock is established, or alternatively fully telescoped into a completely closed position wherein a mechanical lock is effected.

2. Description of Prior Art

Two-piece hard shell cpasules have been utilized since before the turn of the century for holding unit doses of physiologically active agents. Two U.S. Pat. Nos. 525,844 and 525,845 were issued to one R. P. Hobbs on Sept. 11, 1894 claiming a two-piece hard shell capsule having "a cap contracted between its ends, and a body which is straight for some distance from its mouth." Hobbs described his capsule as having a lock fit between the cap and the body of the capsule.

The reasons are not clear, but Hobbs' invention appears never to have been commercially developed, albeit literally hundreds of billions of two-piece hard shell capsules have been manufactured and sold since 1894.

Until sometime in the mid 1960's, the conventional commercial capsule comprised a body portion and a cap portion each of which had essentially straight sides with a diverging taper extending from the point of intersection of the radius of the closed end with the cylinder wall to the open end of the body and cap respectively. The inside diameter of the cap at its open end was greater than the outside diameter of the body at its open end. The inside diameter of the cap diminished progressively from the open end to the closed end, and eventually reached a dimension that was less than the outside diameter of the body at the latter's open end. The capsules were designed so that the point where the inside diameter of the cap and the outside diameter of the body, at the latter's open end, coincided would be at some distance from the beginning of the radius of the closed end of the cap. Friction was depending upon to maintain a tight fit between the body and cap when the capsule was closed by fully telescoping the body into the cap.

However, vagaries in the diameters of pins on which the body and cap portions of the capsule were molded, and in the thickness of the body portion wall at the body's open end resulted in many capsules which had little or no frictional engagement on being fully closed. The lack of a dependable friction engagement in many capsules led to a variety of problems in the handling and shipping of both unfilled and filled capsules. An unfilled capsule which separates before it is fed into the high speed filling equipment in use today causes interruptions in the filling operation with an accompanying reduced productivity. A filled capsule which separates after it has been packaged results in powder or pellets being released into the package with a consequent soiling of good merchandise.

Hostetler, et al., approached this problem, U.S. Pat. No. 3,173,840, Mar. 16, 1965, by horizontally constricting the inside diameter of the cap portion both above and below the point of convergence of the radius of the closed end with the cylinder wall. This was accomplished by a plurality of circumferentially separated lands standing inwardly from the inner surface of the cap cylinder wall. This design provided an area of greater frictional engagement than had theretofore been possible because it allowed the air which is compressed when the body is telescoped into the cap to escape between the separated inwardly standing lands as the capsule is closed completely. The Hostetler, et al., improvement continued to depend wholly on a frictional engagement for the locking of the capsule.

In another patent issued in 1966, U.S. Pat. No. 3,258,115, a substantial modification of the conventional two-piece hard shell capsule was claimed. Basically the cap was telescoped into a redesigned body instead of the usual body into cap closure. Moreover, a redesign of the mid-section of the body and an elongation thereof was disclosed as having provided a superior locking fit. However, the locking still depended on a frictional engagement.

Still another U.S. Pat. issued in 1966, No. 3,285,408, approached the problem of providing a more dependable locking fit utilizing a frictional engagement. In this patent the horizontal constriction of Hostetler was moved completely out of the radius of the closed end and confined entirely to the cylindrical wall of the cap. Moreover the constriction was positioned completely around the circumference of the cap with no separations therein.

U.S. Pat. No. 3,399,803 claimed a locking capsule which shifted the emphasis from a frictional engagement to the mating of an inwardly extending annular ring appropriately positioned in each of the cap and body portions. This in effect accomplished a mechanical locking of the cap and body when the body was fully telescoped into the cap in a fully closed position.

The mechanical locking capsule of U.S. Pat. No. 3,399,803 was elaborated upon in U.S. Pat. No. 3,508,678 in which two inwardly extending indents were provided in the cap between the open end and the inwardly extending annular ring claimed in said U.S. Pat. No. 3,399,803. A pre-locking feature was claimed which aided in preventing the separation of partially closed unfilled capsules.

U.S. Pat. No. 3,584,759 marked a return to a frictional engagement for achieving a locking fit between the cap and body portions of the capsule when the body was fully telescoped into the cap in a completely closed position.

U.S. Pat. No. 3,664,495, issued May 23, 1972, continued the feature of obtaining a locking fit between the body and cap portions of a capsule by a frictional engagement. To accomplish this feature, a pair of diametrically opposed indents were extended radially inwardly from the sides of the wall of the cap. These indents were of sufficient depth to effect a significant reduction in the inside diameter of the cap at the lateral plane in which said indents were positioned, and of a sufficient area to provide a substantial frictional area. Telescoping a conventional tapered body into such a cap results in an immediate contact between the outside diameter of the body and the inside surface of the indents establishing a frictional engagement. A frictional pre-locking feature is thus provided, and when the body is fully telescoped into the cap in a completely closed position the frictional engagement is maintained and stabilized.

In all of the frictional locking capsules described above there is a permanent deformation of either or both the body and cap. In some instances the open end of the body is wedged into the closed end of the cap. In other cases the side walls are distorted into an out of round configuration at the position of the frictional engagement. In all events strains are produced in the capsule walls and the resultant stresses have been known to cause failure of the capsule walls with a concurrent spillage of powder or pellets.

In the capsules which are both pre-locked and locked by mechanical means, there is a point where the open end of the body becomes temporarily circumferentially frictionally engaged with the cap as the body is being telescoped from a partially closed to a fully closed position. And this circumferential frictional engagement continues until the capsule is fully telescoped. When the locking feature depends on a completely circumferential annular indent in the cap, there is no opportunity for the air that is being compressed into the closed end of the cap during the telescoping operation to escape. Consequently, such capsules resist closure and when modern high speed filling machines handling up to 1,000 capsules per minute are utilized, many damaged capsules result from the difficulty encountered in telescoping the body, which is filled with powder or pellets, into a completely closed and locked position in the cap.

The manufacture of two-piece hard capsules is conventionally carried out by independently molding the cap and body portions on corrosion resistant pins. When such two-piece hard capsules are made of gelatin the pins are dipped into a highly viscous gelatin disprsion and slowly withdrawn. By adjusting the viscosity, temperature, rate of withdrawal, etc., the amount of gelatin adhering to the pin can be controlled. The gelatin forms a film which takes on the contour of the pin as the surface tension of the gelatin keeps the file thickness essentially uniform. Hence, the outside surface of the gelatin film has the same general contour as the pin employed as a mold.

The mold pins are lubricated with a special soap-type grease before being dipped into the gelatin. Consequently the molded cap or body portion can be easily removed from the mold pin after the gelatin film has been dried to an appropriate moisture content, generally 14 to 16 percent water.

The cap and body portions of the capsule are mechanically stripped from the mold pins and trimmed to an established length with a rotary knife or by rotating the molded piece against a stationary knife. The trimmed body portion is then mechanically telescoped into the trimmed cap portion to form the two-piece hard capsule.

The empty two-piece hard capsules are collected in a random pack and introduced into the feeding hopper on a capsule filling machine in that form. The feeding hopper rectifies the empty capsules into a position where the body portion is always oriented in the same direction. The rectified capsules are fed into a capsule holding device and the body is separated from the cap, usually by applying vacuum to the body portion while the cap portion is held stationary. The body portion is then filled with powder, granules, pellets, or the like, and rejoined with the cap portion by mechanically telescoping the body into the cap as the latter is held in a stationary position.

Gelatin, the preferred material of which capsules are made, is a hydrophilic colloid which has the capacity to take up and lose water as the humidity varies in the environment to which the gelatin is exposed. As the water content of the gelatin varies there are changes in the dimensions of the capsules formed from the colloid. Consequently it is extremely difficult to design the dimensions of a capsule cap and the capsule body which is telescoped thereinto with sufficient precision as to always maintain a close and sufficient fit to assure that the capsules will not come apart under the conditions of humidity and handling to which they are subjected.

It is important that the fit between the outside surface of the cylinder wall of the body portion and the inside surface of the cylinder wall of the cap of the empty capsule should be snug to hold the capsule together, but not locked to the extent that the separation of the body from the cap is difficult in the filling operation. It is also important that the two-pieces of the capsule should be held together after being rejoined as filled capsules, with as strong a lock as is possible. Yet the lock effected in a completely telescoped filled capsule should not be one that is accomplished with great difficulty. The rejoining operation taking place on modern high speed filling equipment is accomplished in a fraction of a second. And this doesn't provide much time for the air, which is trapped in the closed end of the cap portion when the body portion is telescoped thereinto, to escape and the internal pressure to equalize with the atmospheric pressure on the outside.

Accordingly, it is an object of this invention to provide a two-piece hard capsule which can be pre-locked as an empty capsule to resist separation during handling.

It is yet another object to provide a pre-locked capsule which can be separated easily by the vacuum operation conventionally performed on modern high speed capsule filling machines.

A further object of this invention is to provide a locking capsule which will require only a momentary deformation of the capsue structure in effecting a locked capsule after the capsule has been filled and telescopically rejoined into a fully closed condition.

Another object of this invention is to provide a mechanical lock between the capsule cap and body portions when the two are completely telescoped together that can be effected on high speed filling equipment.

SUMMARY

It has now been discovered that a two-piece hard capsule can be produced which provides the benefits of the frictional contact between the outside surface of the body portion and the inside surface of the cap portion to effect a pre-lock of the empty capsule, and which has the beneficial advantages of a mechanical lock when the capsule is completely telescoped together, without the attendant disadvantage of a slow pressure equilization period during the telescoping operation. This is accomplished by providing raised areas around the circumference on the inside surface of the cap cylinder wall which frictionally engage the outside surface of the body cylinder wall as the body is partially telescoped into the cap to a pre-locked position. A mechanical lock is effected in the fully telescoped capsule by providing a plurality of lateral ridges extending radially inwardly in the same circumferential plane in the cylinder wall of the cap separated by lateral areas which do not extend radially inwardly, and a circumferential constriction in the body between the open and closed end thereof which slips over the lateral ridges in the cap when the two pieces are telescoped together. The lateral areas, between the lateral ridges, which do not extend radially inward provide a conduit through which the air can escape as the body is telescoped into the cap permitting high speed rejoining without an attendant pressure build-up in the closed end of the cap portion of the capsule.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a capsule cap pin.

FIG. 2 is a side view of a capsule body pin.

FIG. 3 is a partial section of the side of a capsule cap pin showing the contour of the location where indents are present on the pin.

FIG. 4 is a partial section of the side of a capsule body pin showing the contour of the location on the pin where a constriction approximating an ogee curve is present on the pin.

FIG. 5 is a cross-sectional view of closed end and part of the cylinder of a capsule cap.

FIG. 6 is a cross-sectional view of the open end and part of the cylinder of a capsule body.

FIG. 7 is a bottom view of the open end of a capsule cap.

FIG. 8 is a top view of the open end of a capsule body.

FIG. 9 is a side view of a completely telescoped locking two-piece hard capsule in the locked position.

FIG. 10 is a cross-sectional view of a completely telescoped locking capsule in the locked position.

FIG. 11 is a cross-sectional view of a locking capsule partially telescoped into the pre-lock position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The novel locking two-piece hard capsule of the instant invention, and the molding pins on which each of the cap and body portions of said capsule are formed are illustrated in the accompanying drawings.

FIGS. 1 and 2 show the contour of the mold pins on which the cap and body portions of the useful locking two-piece capsule of this invention are formed. FIGS. 3 and 4 are blown-up profile views of the surface of the body and cap molding pins respectively at the location on the pin where the elements which effect the locking capsule of the present invention are formed in the cylinder wall of the body and cap portions, respectively.

Referring to FIG. 1, the salient features of the cap molding pin 1, on which the cap portion of the locking capsule of this invention is molded, are shown. The surface of the cylinder wall 2 tapers outwardly, in relation to the axial center-line of the pin, away from the end 5 of the pin 1 whereon the closed end of the cap is formed. In the design of a two-piece hard capsule it is beneficial to have the cap portion tapering outwardly from the closed end to the open end thereof as this allows for a greater clearance between the outside diameter of the body portion and the inside diameter of the cap at the open end. This makes the rejoining operation easier as it is not required that the centering of the body with the cap should be extremely precise. Once the body has been started into the cap it is a benefit to have the clearance between the two dimensions described above decrease so that a close fit is accomplished when the body is completely telescoped into the cap. A plurality of independent lateral indentations 3 are formed in the cap pin which result in radial inwardly extending lateral ridges in the inside surface of the cap. There is an area between each of the indentations that is not indented so that the ridges are laterally separated. Disposed between the ends of the lateral indentations 3 are a plurality of longitudinal indentations 4 which originate in said lateral indentations 3 distant from the end 5 of the pin and progress away from the end 5. The longitudinal indentations 4 blend into the lateral indentations 3, and there is generally one longitudinal indentation 4 associated with each lateral indentation 3. This, however, is not a requirement, and as long as longitudinal indentations are disposed at approximately equal distances around the circumference of the pin, raised areas extending radially inwardly are formed in the cap which effect a frictional contact between the inside surface of the cap and the outside surface of the body. Generally three lateral indentations are sufficient to provide an effective number of lateral ridges extending radially inwardly in the cap and three raised areas disposed between the ends thereof suffice. The total length of the lateral indentations should not, as a rule, exceed about 300.degree. of the circumference of the pin.

A profile of the lateral indentation 3 and the longitudinal indentation 4 is shown in FIG. 3. The longitudinal indentation 4 originates in the slope of the side of lateral indentation 3 and progresses away from the latter. The longitudinal indentation 4 is generally about two-thirds the depth of the lateral indentations 3, but can be of equal depth. It is imperative that the longitudinal indentation 4 originate in the lateral indentation 3 as it is essential that the two indentations blend together so that there will be no area in the inside surface of the cylinder wall of the cap between the lateral ridges and the longitudinal raised areas that extends radially inwardly by a lesser amount than said raised areas.

Referring to FIG. 2, a body mold pin 6 is shown from a side view. The pin has a general taper inwardly toward the end 12 of the pin on which the closed end of the body is formed. There is a constriction 7 in the pin which is in the geometric form of a longitudinally extending ogee curve. The ogee curve provides the benefit over a chamfer of a smoother leading and trailing edge which reduces the opportunity for the formation of bubbles in the gelatin film at the point of change in the line of the cylinder wall of the mold pin. The longitudinally extending ogee curve is disposed laterally around the circumference of the pin, and effects a uniform reduction in the diameter of the pin. The cylinder wall 8 of the pin immediately adjacent to the ogee curve 9 tapers outwardly away from said curve. The cylinder wall 10 immediately adjacent to the ogee curve 9 is essentially parallel to the axial center-line of the pin for a distance toward the end 12 of the pin to the point where the essentially parallel wall intersects a line projected from the intersection of the tapered wall 8 with the ogee curve 9 toward the end 12 of the pin at the same degree of taper as is present in the tapered wall 8. From this point until the cylinder wall 11 intersects with the beginning of the radius of the end 12 of the pin, the taper of the cylinder wall progresses at about the same degree as is present in the cylinder wall 8.

The profile of the body pin 6 at the position of the constriction effected by the longitudinally extending ogee curve 9 in said pin 6 is blown up in FIG. 4. The cylinder wall 8 tapers inwardly to the point of intersection with the leading edge of ogee curve 9. Ogee curve 9 progresses away from cylinder wall 8 toward cylinder wall 10. Cylinder wall 10 progresses away from ogee curve 9 essentially parallel to the axial center line of pin 6. The distance covered by ogee curve 9 occupies from about one-twentieth to about one-tenth of the total distance from the end of the pin to the far edge of the ogee curve 9, and provides for a constriction of from about 0.004 to about 0.008 inches in the diameter of the pin from the beginning to the end of said ogee curve 9.

In practice, the capsule body is trimmed to provide a section between the open end of said body and the beginning of the ogee curve 9 which occupies from about one-thirtieth to about one-tenth of the total length of said body after trimming.

The cap portion 13 of the novel locking capsule of this invention is shown in cross-section in FIG. 5. The cap 13 has a cylinder wall 14 which is of essentially the same thickness throughout. The inside surface 15 of said cylinder wall 14 conforms to the outside surface of the molding pin, such as that shown in FIG. 1, on which the cap 13 is formed. And because the thickness of the cylinder wall 14 is essentially uniform regardless of the contour, the outside surface 16 generally follows the inside contour. For that reason the outside surface is depressed where the indentations 3 and 4 were present in the mold pins on which said cap was formed.

The raised area 17 is shown in FIG. 5 extending radially inwardly and the lateral ridges 19 also extend radially inwardly. The indentations 18 and 20, which are observed in the outside surface 16 are opposite said raised areas 17 and said lateral ridges 19, respectively. The raised areas 17 originate at the lateral ridges 19 and are disposed between the ends thereof. The raised areas 17 progress away from the lateral ridges 19 toward the open end of said cap portion 13.

There is a plurality of lateral ridges 19 disposed in the same circumferential plane with the apex thereof at a distance of from about one-tenth to about one-thirtieth of the total length of the cylinder wall 14 from the point of the intersection of the latter with the closed end 21 of said cap 13. Preferably the apex of the lateral ridges 20 is about one-twentieth of the cap length as described above.

While there may be any number of independent lateral ridges 19 from two to infinity, the maximum feasible number would be about 12. Preferably there are three independent lateral ridges 19. Each of the independent lateral ridges 19 is separated from the next lateral ridge around the circumference by a section of the inside surface 15 of said cap which is a lateral and longitudinal continuation of said inside surface 15 of said cylindrical wall 14. The lateral ridges 19 are extended radially inwardly from about 0.002 to about 0.005 inches from the inside surface 15. Preferably the inward radial extension is about 0.003 inch at the apex of said lateral ridges 19.

The raised areas 17 disposed between the ends of said lateral ridges 19 are extended radially inwardly from about 0.0015 to about 0.0035 inch, preferably about 0.002 inch.

The plurality of lateral ridges 19 have a total length of from about 180.degree. to about 300.degree., preferably about 300.degree.. And the separations between said lateral ridges 19 have a total length of about 60.degree. to about 180.degree., preferably about 60.degree..

The separation areas between said lateral ridges 19 serve the purpose of providing a conduit for the rapid escape of the air from the closed end 21 of said cap 13 when the body portion 22 of said capsule shown in FIG. 6 is fully telescoped into said cap 13.

The raised areas 17 blending into the lateral ridges 19 have a total lateral distance of from about 90.degree. to about 180.degree., preferably about 90.degree. and occupy a longitudinal distance of from about one-tenth to about one-fourth of the total length of said cap 13, preferably about one-sixth.

The closed end 21 of said cap 13 is shown in FIG. 5 as a hemisphere. While this is the preferred geometric form of said closed end 21, such is not a requirement, and said closed end 21 can be in any reasonable combination of radii that avoids sharp angles.

A bottom plan view of said cap portion 13 is show from the open end in FIG. 7. The raised areas 17 are shown as located in essentially the center of each of the lateral ridges 19, such a positioning is not required as said raised areas can be located at any point between the ends of the lateral ridges 19. Geometric symmetry suggests the centerline position and such is preferred. Moreover, the separations between the lateral ridges are shown as being essentially uniform, such geometric exactness is not required, but some reasonable symmetry is indicated to aid in the uniform escape of the air being compressed in the closed end 21 of the cap as the body portion is being fully telescoped thereinto.

The pin on which the cap 13 is molded is designed to provide an inside diameter in the section of the cap 13 between the near edge of said lateral ridges 19 and the point of intersection of the cylinder wall 14 and the beginning of the closed end 21 that is about the same as the outside diameter of the body 22 at the open end 33 of the latter.

The body portion 22 of the useful locking capsule of the present invention is shown in FIG. 6. The body 22 has a cylindrical wall 23 that is of about the same thickness as the cylinder wall 14 of the cap 13. The inside surface 24 of said body 22 follows the contour of the pin 6 on which said body 22 is molded. And the outside surface 25 follows generally the contour of said inside surface 24, as was discussed hereinbefore in connection with said cap 13. It is the outside surface 25 of said body 22 which provides, in combination with the inside surface 15 of said cap 13 the elements which constitute this invention. The elements of the two portions cooperate to effect the novel locking capsule disclosed herein.

The heart of the body 22 elements cooperating with the cap 13 elements is the construction 27 in the body 22 in the geometric form of a longitudinally extending ogee curve beginning at the intersection of said ogee curve and a tapered section 26 and ending at the intersection of the opposite end of said ogee curve and a section of said body 22 wherein said cylinder wall is essentially parallel with the axial centerline of said body 22.

The capsule body portion 22 is comprised of five longitudinally integrally molded sections, each intersecting with the next to effect a continuous cylinder wall from an open end to a closed end.

The first section 26, shown in FIG. 6, extends from the open end 33 toward said closed end of said body 22, said first section 26 occupying from about one-thirtieth to about one-tenth of the total length of said body 22, preferably about one-twentieth, and tapers progressively inwardly in relation to the axial center line of said body 22. Said taper progresses at from about 0.005 to about 0.020, preferably about 0.012 inch per linear inch. Said first section 26 has an outside surface diameter at the open end 33 of about the same diameter as the inside of the cap surface at the point in the cap portion 13 where the cylinder wall and closed end intersect.

The second section 27 of said body 22 is a constriction which reduces the diameter of the outside surface 25 of said body 22 by from about 0.004 to about 0.008 inches over a span of from about one-twelfth to about one-twenty-fourth of the total length of said body 22. Preferably, said diameter is reduced by about 0.004 inch over a span of about one-twentieth of the total length of said body 22. The constriction progresses in the geometric form of a longitudinally extended ogee curve having two inverted radii of about 0.050 and 0.120 inches, respectively. The ogee curve is laterally continuous around the circumference of said body 22. The second section 27 is integrally molded with said first section 26.

The third section 28 of said body 22 occupies from about one-fifth to three-fifths of the total length of said body 22, preferably about two-fifths, and has a cylinder wall that is essentially parallel to the axial center line of said body from the point of intersection with the trailing edge of the ogee curve of said second section 27 to the point of intersection with a projected line, having the same taper as said first section 26, from said first section 26 with the parallel walls of said third section 28. Said third section 28 is integrally molded with said second section.

The fourth section 29 continues with the same taper as said first section 26 from the intersection of said third section 28 with said fourth section 29 to the intersection of the latter with the fifth section 30 which constitutes the closed end 30 of said body portion 22. Said fourth section, integrally molded with said third section, occupies from about one-eighth to two-fifths of the total length of said body 22, preferably about one-fourth of said length.

The fifth section 30 of said body 22 constitutes the closed end of said body 22 and is integrally molded with said fourth section 29. Said fifth section occupies from about one-eighth to about two-fifths of the total length of said body 22, preferably about one-fourth, and can have any geometric form that avoids sharp angles, preferably either a hemisphere or a parabola.

A top plan view from the open end of said body 22 is shown in FIG. 8. The inside and outside walls are laterally symmetrical as illustrated.

A completely closed capsule is shown in FIG. 9 with the indentations in the outside surface 16 of the cap where the lateral ridges 19 and raised areas 17 appear on the inside of the cap positioned to serve as a reference for the cross-sectional views of a completely telescoped capsule shown in FIG. 10 and the partially telescoped capsule detailed in FIG. 11.

In FIG. 10 the first section 26 of the body 22 is shown telescoped into a position between the lateral ridges 19 and the closed end 21 of the cap. The second section 27 of said body 22 is located adjacent to the lateral ridges in the same circumferential plane. As said body 22 is telescoped to a point where the open end 33 of said body 22 contacts the first edge of said lateral ridges 19, a frictional grip is effected and the air in the closed end 21 of said cap 13 comes under compression. As the telescoping continues the air escapes between the ends of the lateral ridges 19 and the first section 26 of the body 22 is compressed and deforms as it slides up on the lateral ridges 19, and returns to its original configuration as it slides down the back side of said lateral ridges 19. As said first section 26 slides completely behind said lateral ridges 19, said first section has an outside surface diameter greater than the inside diameter of the lateral ridges 19 and consequently a mechanical grip is established between the cap portion 13 and the body portion 22 of the novel locking capsule of this invention. The cylinder wall of the third section 28, being parallel to the axial center-line of the body 22 clears the raised areas 17, but remains close the latter. Moreover, inasmuch as the cap portion 13 is tapering outwardly from the closed end to the open end thereof, the parallel cylinder wall of the third section 28 of the body portion 22 establishes a smaller clearance between the outside surface 25 of the cylinder wall 23 of the body 22 and the inside surface 15 of the cap 13 than that which would be present if the taper of the body 22 were resumed immediately after the termination of the second section 27, and aids in the release of air from the completely telescoped capsule. The mechanical lock thus effected provides a superior resistance to the separation of a filled capsule when the latter is subjected to severe punishment in handling and packaging.

A partially telescoped capsule is illustrated in FIG. 11. The first section 26 of the body 22 is shown in frictional contact with the raised areas 17 which extend radially inwardly from the inside surface of the cap 13. In this position there is sufficient frictional contact to hold the partially telescoped capsule together under most conditions encountered in handling and shipping empty capsules and in the feeding mechanisms on high speed filling machines. And yet the frictional pressure is not so great that an easy separation of the cap can not be achieved in the conventional filling operation.

Moreover, the positioning of the said areas 17 between the ends of lateral ridges 19, and the blending of longitudinal ends of the former into the sloping side of the latter provides a clear and continuous open channel for the escape of air from the closed end of the cap 13 as the body 22 is telescoped thereinto, and assures that first section 26 of the body 22 will not become mechanically locked when the body 22 is partially telescoped into the cap 13 in a prelocked position.

Claims

What is claimed is:

1. A locking two-piece hard capsule comprising a cap portion and a body portion, said body portion telescoping into said cap portion effecting a frictional pre-lock when said body is partially telescoped into said cap and a mechanical lock when said body is completely telescoped into said cap, said capsule comprising:

1. an essentially cylindrical cap portion having a closed end and an open end with the cylinder wall tapering generally outwardly from said closed end to said open end, said cylinder having an inside diameter at the intersection of said cylinder wall and said closed end about the same as the maximum outside diameter of the cylinder wall of the body portion which telescopes into said cap, said cap having a plurality of individual lateral ridges disposed in the same circumferential plane and extending radially inwardly from the inner surface of said cylinder wall of said cap, each lateral ridge separated from the next lateral ridge around said circumference of said cap by an area that is a lateral and longitudinal continuation of said inner surface of said wall, and a plurality of raised areas extending radially inwardly from the inner surface of the cylindrical wall of said cap, each of said raised areas disposed between the ends of a lateral ridge and extending from said lateral ridge toward said open end of said cap; and

2. an essentially cylindrical body portion having a closed end and an open end, said cylinder having an outside diameter at the open end about the same as the inside diameter of said cap, into which said body telescopes, at the intersection of the cylinder wall of said cap with the closed end thereof, and comprising:

a. a first section extending from said open end toward said closed end with the cylinder wall tapering generally inwardly in relation to the axial centerline of said body,

b. a second section, integrally molded with said first section, extending from said first section toward said closed end in which the surface of the cylinder wall is progressively constricted inwardly in the shape of a geometric form characterized as an ogee curve,

c. a third section, integrally molded with said second section, extending from a point tangent to the trailing radius of said ogee curve toward said closed end, the cylinder wall of said third section being essentially parallel to the axial center line of said body,

d. a fourth section, integrally molded with said third section, extending toward said closed end from the point where a projection of the inwardly tapering cylinder wall of said first section intersects the surface of said essentially parallel cylinder wall, said fourth section tapering inwardly at essentially the same rate as said first section, and

e. a fifth section, integrally molded with said fourth section, said fifth section constituting the closed end of said body.

2. A locking capsule as defined in claim 1 wherein the plurality of lateral ridges occupy a total of from about 180.degree. to 300.degree. of the circumference of said cap, and the lateral continuations of the inner surface of the cylinder wall between said lateral ridges occupy a total of from about 60.degree. to about 180.degree. of the circumference of said cap.

3. A locking capsule as defined in claim 1 wherein there are three lateral ridges in the same circumferential plane of said cap, each ridge approximately equidistant from the next and extending through an arc of from about 60.degree. to about 100.degree..

4. A locking capsule as defined in claim 3 wherein each lateral ridge extends through an arc of about 100.degree..

5. A locking capsule as defined in claim 1 wherein the plurality of said raised areas disposed between the ends of said lateral ridges occupy a total lateral surface of from about 90.degree. to about 180.degree. of the circumference of said cap, and the longitudinal dimension of each of said raised areas is from about one-tenth to about one-fourth of the total length of said cap.

6. A locking capsule as defined in claim 1 wherein there are three raised areas each of which is disposed between the ends of each of three lateral ridges, each raised area having a lateral dimension of from about 30.degree. to about 90.degree. and a longitudinal dimension of about one-tenth to about one-fourth of the total length of said cap.

7. A locking capsule as defined in claim 6 wherein each raised area has a lateral dimension of about 30.degree. and a longitudinal dimension of about one-sixth the total length of said cap.

8. A locking capsule of claim 1 wherein said raised areas extend radially inwardly from about 0.0015 to about 0.0035 inches from the inner surface of the wall of said cap.

9. A locking capsule of claim 1 wherein said lateral ridges extend radially inwardly at the apex from about 0.002 to about 0.005 inches from the inner surface of the wall of said cap.

10. A locking capsule of claim 1 wherein said cap has three lateral ridges in the same circumferential plane extending radially inwardly at the apex about 0.003 inches and occupying about 300.degree. of the circumference of said cap, said lateral ridges disposed about one-tenth of the distance from the intersection of the cylindrical wall of said cap with said closed end and said open end and three raised areas, each extending radially inwardly about 0.002 inches, each disposed between the ends of one of said lateral ridges and extending laterally through about 30.degree. and longitudinally about one-sixth the total length of said cap.

11. A locking capsule according to claim 1 wherein said first section of said body is from about one-thirtieth to about one-twelfth of the total length of said body, and the cylinder wall of said first section tapers inwardly from said open end toward said closed end at a rate of from about 0.005 to about 0.020 inch per linear inch.

12. A locking capsule according to claim 1 wherein said second section of said body is a constriction progressing from the point of departure from the tapered cylinder wall of said first section toward said closed end and occupying from about one-thirtieth to about one-twelfth of the total length of said body, said constriction being characterized by an ogee curve having inverted radii of about 0.050 and 0.120 inches, respectively.

13. A locking capsule according to claim 1 wherein the inside diameter of said body is reduced by from about 0.004 to about 0.008 inches from the intersection of said ogee curve and the trailing edge of said first section to the intersection of the trailing edge of said ogee curve and said third section.

14. A locking capsule according to claim 1 wherein said third section of said body occupies from about one-fifth to about three-fifths of the total length of said body, and the cylinder wall of said third section is essentially parallel with the axial center-line of said body from the intersection of said third section with the trailing edge of said ogee curve of said second section to the intersection of said third section with the leading edge of said fourth section.

15. A locking capsule according to claim 1 wherein said fourth section of said body comprises from about one-eighth to about two-fifths the total length of said body, and the cylinder wall tapers inwardly from the intersection of said fourth section with said third section at a rate of from about 0.005 to about 0.020 inch per linear inch.

16. A locking capsule according to claim 1 wherein said fifth section of said body comprises said closed end of said body and occupies from about one-eighth to about two-fifths of the total length of said body.

17. A locking capsule according to claim 1 wherein said body comprises:

a. a first section beginning at said open end of said body and extending toward said closed end of said body with the cylinder wall tapering inwardly toward the axial center-line of said body at a rate of about 0.012 inch per linear inch, said first section having an outside diameter at said open end about the same as the inside diameter of said cap at the point of intersection of the cylinder wall and the closed end of said cap and occupying about one-thirtieth of the total length of said body;

b. a second section integrally molded with said first section constricting the outside diameter of said body by about 0.004 inch from the trailing edge of said first section to the leading edge of said third section, said second section having the geometric form of a longitudinally extending ogee curve and occupying about one-twentieth of the total length of said body;

c. a third section integrally molded with said second section, said third section occupying about two-fifths of the total length of said body and having a cylinder wall essentially parallel to the axial center-line of said body;

d. a fourth section integrally molded with said third section, said fourth section occupying about one-fourth of the total length of said body and having a cylinder wall tapering at the rate of about 0.012 inch per linear inch from the intersection of said fourth section with said third section to the intersection of said fourth section with said fifth section; and

e. a fifth section integrally molded with said fourth section, said fifth section occupying about one-fourth of the total length of said body and constituting the closed end of said body, said closed end being rounded.

18. A locking capsule according to claim 17 wherein said closed end of said body is in the geometric form of a parabola.

19. A locking two-piece hard capsule comprising a cap portion and a body portion, said body portion telescoping into said cap portion effecting a frictional pre-lock when said body is partially telescoped into said cap and a mechanical lock when said body is completely telescoped into said cap, said capsule comprising:

1. an essentially cylindrical cap portion having a closed end and an open end with the cylinder wall tapering generally outwardly at the rate of about 0.012 inch per linear inch from said closed end to said open end, said cylinder having an inside diameter of about the same at the intersection of said cylinder wall and said closed end as the maximum outside diameter of the cylinder wall of the body portion which telescopes into said cap, further said cap having three lateral ridges disposed about one-tenth of the distance from the intersection of the cylinder wall with the closed end of said cap and said open end of said cap, said lateral ridges being in the same circumferential plane and extending radially inwardly at the apex about 0.003 inches and occupying about 300.degree. of the circumference of said cap, said cap also having three raised areas each extending radially inwardly about 0.002 inches and each disposed between the ends of one of said three lateral ridges, each of said raised areas extending longitudinally from said lateral ridges toward said open end about one-sixth of the total length of said cap and extending laterally through about 30.degree. of the circumference of said cap; and

2. an essentially cylindrical body having a closed end and an open end, said cylinder having an outside diameter at the open end thereof about the same as the inside diameter of the cap, into which said body telescopes, at the intersection of the cylinder wall of said cap with the closed end thereof, and comprising:

a. a first section beginning at said open end of said body and extending toward said closed end of said body with the cylinder wall tapering inwardly toward the axial center of said body at a rate of about 0.012 inch per linear inch, said first section occupying about one-thirtieth of the total length of said body;

b. a second section, integrally molded with said first section, constricting the outside diameter of said body by about 0.004 inch from the trailing edge of said first section to the leading edge of said third section, said second section having the geometric form of an ogee curve and occupying about one-twentieth of the total length of said body;

c. a third section, integrally molded with said second section, said third section occupying about two-fifths of the total length of said body and having a cylindrical wall essentially parallel to the axial center-line of said body;

d. a fourth section, integrally molded with said third section, said fourth section occupying about one-fourth of the total length of said body and having a cylindrical wall tapering inwardly toward the axial center-line of said body at the rate of about 0.012 inch per linear inch from the intersection of said fourth section with said third section to the intersection of said fourth section with said fifth section; and

e. a fifth section integrally molded with said fourth section, said fifth section occupying about one-fourth of the total length of said body and constituting the closed end of said body, said closed end being rounded.

20. A locking capsule according to claim 19 wherein said closed end of said body has the geometric form of a parabola.