US2039757A - Molded cap - Google Patents

Description

May 5, 1936- A. VON TILL 2,039,757

MOLDED CAP Filed Dec. 12, 1930 2 Sheets-Sheet 1 Z! .3 v INVEQTOR A0 11A. V0 2T2?! M ATTORNEY y 1936- 1.. A. VON nu.

MOLDED CAP Filed Dec. 12, 1930 2 Sheets-Sheet 2 INVENTOR lazzzlrA. V021 Tzll ATTORNEY Patented May 5, 1936 MOLDED CAP Louis A. Von Till, Brooklyn, N. Y., asslg'nor to Anchor Cap & Closure Corporation, Long Island City, N. Y., a corporation of New York Application December 12, 1930, Serial No. 501,803

14 Claims.

The present invention relates to the sealing art and more particularly to a molded closure cap for application to containers, preferably glass containers.

The material in molded closure caps represents a substantial part of the cost thereof. For this reason, it is desirable to decrease, as far as possible, the weight of such caps which can be done by decreasing the thickness of the walls thereof or by decreasing the length of the skirt. The thickness of the walls must be suflicient to make the cap rugged and strong enough to withstand the strains occasioned in application to a container. The length of the skirt is governed, to a substantial extent, by the pitch of the thread,

which is standardized by reason of the fact that the containers to which they are applied are standardized. Considerable difliculty has been occasioned with such caps due to the fact that, in an effort to shorten the skirt of the cap, the length of the thread therein has not been sufficient to extend completely about the container thread. Improper fits also cause defective seals and substantial cap breakage during application thereof. Other difliculties have been occasioned due to the fact that the liners which are necessary to engage the mouth of the container to form the seal, tend to fall out of the caps. Attempts have been made to remedy these and other objections, but such attempts havenot been successful.

In the manufacture of molded closure caps, the customary method is to utilize a die or pin with screw threads thereon to fit into the cap, and a mold enveloping said cap to form the exterior of the cap, these two being pressed together to form the cap. Unscrewing the caps from the pin is tedious and expensive. It has been found that caps having proper shapes of thread may be removed from the pins by pressure applied axially thereof; in other words, the cap is stretched sufficiently to strip over the threads on the pin. This is possible because of the resiliency of the caps while in their heated state. The operation, however, is a difilcult one with present types of caps. Attempts, heretofore; to facilitate the operation have impaired the efficiency of the seal made when applied to a container.

The present invention aims to eliminate the above difilculties by providing an inexpensive closure cap with a skirt of minimum length adapted to properly fit and grip the container thread throughout the circumference of the container to apply a uniform sealing pressure throughout the periphery of the cap and also adapted to seat and retain the liners in position without interfering with the application of the cap and without increasing the cost thereof. The invention also aims to provide a cap which may be readily stripped from the threads on the pins upon which they are made and, atthe same time, provide a secure seal on containers.

' An object of the present invention is to provide an inexpensive molded closure cap adapted to form a secure seal on containers.

Another object of the invention is to provide a molded cap which can be easily manufactured at low cost.

Another object of the invention is to provide an improved molded closure cap adapted to prevent the loss of liners without interfering with the application of the caps.

Another object of the invention is to minimize breakage of caps and imperfect seals by providing an accurate fit betweenthe cap and con tainer.

Another object of the invention is to increase the length of the thread in a cap having a skirt of given length.

Another object of the invention is to improve the sealing qualities of the cap by producing a thread adapted to engage the container thread throughout the circumference of the container and thereby draw the cap downwardly throughout its periphery.

Another object of the invention is to provide a ledge adapted to seat a liner without interfering with the application of the cap.

Another object of the invention is to provide means in the upper part of a closure cap adapted to co-operate with the upper end of the thread therein to prevent loss of liners.

A further object of the invention is to facilitate the manufacture of molded caps by providing a construction which may be readily stripped from the threaded pins upon which they are formed.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings, forming a part of the specification, wherein Fig. 1 is a sectional view of a cap illustrating the present invention;

Fig. 2 is a sectional view of the cap shown in Fig. 1 applied to a container;

Fig. 3 is a flattened view of the interior of the skirt of the cap, showing the construction of the thread therein;

Fig. 4 is a horizontal sectional view through the cap taken on the line 4-4 of Fig. 1, illustrating details thereof;

Fig. 5 is a sectional view of a modified form of cap, illustrating the invention;

Fig. 6 is a flattened view of the interior of the skirt of the cap shown in Fig. 5;

Fig. 7 is a detailed view illustrating a modified construction applicable to the preceding illustrations;

Fig. 8 is a sectional view along the line 8--8 of Fig. '7; and

Fig. 9 is a fragmentary sectional view illustrating a slightly different construction.

Referring again to the drawings; and more particularly to Figs. 1 to 4 thereof, there is shown a closure cap having a cover part I and a depending skirt 2, with a thread 4 molded on the interior of the skirt. The thread'of this cap differs from those previously utilized in structures of this character in several particulars. The lower end 5 of the thread, beginning a substantial distance from the end thereof, decreases in width without decreasing the distance that it projects inwardly. The advantage of this construction is that the thread at its lower end is increased in length without a corresponding increase in the length of the skirt of the cap and without change in the pitch of the thread. The upper side 6 of the lower end of the thread has the same inclination as the other portions of the thread but the lower side I of this part of the thread is substantially parallel to the bottom of the skirt of the cap. The increase in the length of the thread occasioned by the shape of the lower end thereof, causes the cap to grip the container thread throughout a greater angle without increasing the length of the skirt of the cap. The upper end 8 of the thread of the cap terminates a substantial distance below the cover part of the cap to provide ample clearance for a liner which is adapted to be inserted within the skirt of the cap adjacent the cover portion thereof.

In Fig. 2, the cap is shown applied to a container 9 having the customary screw thread l0 thereon. In constructions heretofore, the groove II in the cap is provided to envelop the thread on the container and this groove extends substantially beyond the termination of the upper end of the thread of a container, on normal sizes thereof. The reason the thread on the cap extends beyond the thread on the container is that the dimensions in both the cap and container vary within predetermined limits. Therefore, in some cases, the thread on the container will extend further up on the cap than in other cases. Hence, the thread on the cap must extend sufficiently far to accommodate the smallest containers permissible. The upper end 8 of the thread on the present closure differs from these prior structures in that the groove II, at the upper end of the thread, terminates a substantial distance short of the end of the thread on the container. The inwardly projecting part 8 of the thread, however, extends sufliciently far to be completely effective on all ranges of sizes of containers. The upper end of the thread, however, engages only the lower side of the thread on a container. This is the effective part of the thread in applying the sealing pressure to the container. In this way, the length of the thread in the cap is actually decreased at the upper end thereof very substantially, without impairing in any way the sealing qualities of the cap. An advantage of the construction is that the shorter length of thread in the cap facilitates stripping the cap from the threaded molding pins in the process of manufacture.

It is customary to provide liners of cardboard, cork, felt or other suitable material for molded caps, which are inserted in the caps and seated against the cover portions thereof. The purpose of the liner is to engage the rim of the container when the cap is applied, to form a seal thereon. In addition, the liner tends to take up variations in sizes of containers and to minimize the efiect of slight imperfections at the sealing surfaces of the containers. Considerable difliculty is occasioned due to the fact that the liners tend to-fall out of the caps during shipmentand handling, after being placed therein by manufacturers.

The present invention contemplates the provision of a circumferential ledge 12 adapted to seat and hold the liners in position against the cover portion of the cap. The ledge I2 is not continuous about the skirt of the cap but extends for a major part of the circumference of the cap. Good results have been obtained with a ledge 250 in length. The discontinued portion of the ledge serves a two-fold purpose. In the first place, a discontinuous ledge is more easily stripped from the pins used in manufacture than one which extends completely around the cap. In the second place, the discontinued part of the ledge, in the present cap, is located above the upper end 8 of the thread on the cap so that ample clearance is provided for the thread on the container. In other words, the upper end l4 of the thread on the container, as it passes along the upper end 8 of the thread of the cap, is not obstructed by the ledge l2 because the ledge is discontinued at this point above the upper end of the thread 8 of the cap. In addition, the upper end 8 of the thread co-operates with the ledge l2 to retain the liner in position.

Referring more particularly to Figs. 5 and 6, the cap shown therein diflers from the one described above in that the thread l5, corresponding to the thread 4 in the cap described above, has its upper end extending the usual length. In other words, the groove H therein is adapted to envelop the upper end of the thread of the container on both sides of the thread. The ledge I2 for seating and holding the gasket in position, is substantially similar to the ledge in Figs. 1 and 2, except that certain portions of the ledge, as shown at I 6, merge with the thread on the cap. The ledge is discontinued along the portion of the skirt which is adapted to receive the upper end of the thread on the container. This provides ample clearance for the upper end of the thread on the container and, at the same time, facilitates the stripping operation necessary to remove the cap from the pins on which they are formed. It will be understood that, so long as the ledge extends more than half way about the circumference of the cap, the liners will be held in proper position. In the present embodiment, the ledge extends throughout substantially twothirds of the periphery of the cap. In addition, the upper end of the thread of the cap ends below the discontinued part of the ledge and, therefore, supplements the action of the ledge to hold the liners in position.

A slightly different construction, applicable to the lower ends of the threads in each of the caps described above, is shown in Figs. 7 and 8. In these constructions, the lower end I! of the thread decreases in width without decreasing the depth of the inwardly projecting part. The bottom of the skirt extends into and cuts through the thread to eliminate the lower part thereof. This construction, if desired, may be applicable to either of the caps described above.

In applyingclosure caps, there is a tendency for the cap to be screwed on too tight, sometimes resulting in breaking the cap. Suflicient pressure should -be applied to the liner to provide a good seal, additional pressure does not materially increase the security of the seal. In Fig. 9, a portion of a cap is shown which, for illustrative purposes, is similar to the cap of Fig. 1, with a vertical rib or projection l9 extending from the end of the ledge l2to the upper end 8 of the thread 4. This projection I9 is in the path of the upper end of the thread on the container and serves as a stop to prevent further rotation of the cap. The position of the stop is preferably such that it does not engage the end of the thread on the container unless and until the cap is applied with excessive force.

Preferably, the caps are formed with the threads and ledges, as described above, by utilizing a pin which fits into the cap and by utilizing a mold which telescopes about the pin to provide a matrix for the molding composition. The mold is removed and the cap stripped from the threads; thereafter, a liner I3 is inserted into the cap and caused to seat between the ledge l2 and the cover part of the cap. The caps are then applied to suitable containers as ordinary screw caps are usually applied. The upper end of the thread on the container comes to rest adjacent the upper end of the thread on the cap at that portion of the cap where the ledge is discontinued. The path of the upper end of the threadon the container is, therefore, unobstructed. The lower end of the thread on the cap extends sumciently far to permit the thread to grip the thread on the container throughout at least 360 so that the cap may be pulled down evenly on the container at all points. If the thread engages the thread on the container for a less extent, the pressure will be concentrated at certain points and the cap may break.

It will be seen that the present invention provides a molded closure cap adapted to effect a very secure seal, thereby minimizing breakage of caps. The cap may be readily manufactured at a low cost. Provision is made for securing the liners in position without increasing the cost of the cap or complicating the manufacture thereof. The operation of stripping the caps from the pins, in the manufacture thereof, is greatly facilitated. Further, the caps are rugged in construction and fully capable of withstanding the rough usage to which they may be subjected.

As various changes may be made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in a limiting sense. I

Having thus described my invention, I claim:

1. As an article of manufacture, a molded screw closure cap having a cover portion and a depending skirt, a substantially horizontal ledge on the interior of said skirt adjacent the cover part of the cap adapted to seat and hold a liner in position, said ledge being independent of the screw thread in the cap and being discontinued for a substantial part of its length.

2. As an article of manufacture, a molded closure cap comprising the combination of a. cover part, a depending skirt, a screw thread on the interior of said skirt, and a discontinuous ledge abovev said screw thread extending about the circumference of the cap and adapted to hold a liner in position therein, said ledge being discontinued for substantially one-third of the circumference of the cap.

3. As an article of manufacture, a molded cap comprising a cover portion, a depending skirt, a screw thread on the interior of said skirt, and a horizontal ledge extending only partially around the skirt of the cap to seat a. liner therein, the discontinued portion of the ledge being in position to receive the upper end of the thread of a container when the cap is applied to a container.

4. As an article of manufacture, a molded cap comprising a cover portion, a depending skirt, a screw thread in said skirt, a horizontal ledge extending part of the way about the periphery of the cap to seat a liner, said ledge merging at one end with the upper end of the thread of the cap. 1

5. As an article of manufacture, a molded closure cap having a circumferentially extending horizontal ledge adjacent the cover portion thereof, said ledge being discontinued at least at one part thereof to receive the upper end of the container thread when the cap is applied to a container, thereby to prevent interference with the upper end of the screw thread on a container when the cap is applied to a container.

6. As an article of manufacture, a molded closure cap having a screw thread on the interior of the skirt thereof, a horizontal ledge extending part of the way about the skirt of the cap to seat a liner, one end of said ledge merging into the upper end of the thread of the cap and the other end of said ledge terminating a substantial distance from the upper end of the thread of said cap and substantially in line with it.

7. As an article of manufacture, a closure cap having a depending skirt, a screw thread on the interior of said skirt, and a projection adjacent the upper end of the thread adapted to engage the upper end of the thread on a container and to stop the rotation of the cap.

8. As an article of manufacture, a molded closure cap having a depending skirt, a screw thread on the interior of said skirt, and a projection adjacent the upper end of the thread extending vertically of the skirt of the cap in the path of the upper end of the thread on a container to stop the rotation of the cap at a predetermined point in the application thereof.

9. As an article of manufacture, a molded closure cap comprising a cover portion, a depending skirt, and a screw thread on the interior of said skirt, the central portion of said thread being of one width and the lower portion of said thread being of less width, the lower side of the lower end of the thread being substantially parallel to the bottom edge for a substantial part of the circumference of the skirt to increase substantially the length of the thread with a given length of skirt and being spaced upwardly from the bottom of the skirt to prevent breakage of the cap in stripping it from a molding pin.

10. As an article of manufacture, a molded closure cap comprising a cover portion, 3. depending skirt, a liner retaining ledge in the upper part of the skirt, said ledge being discontinued for a sub stantial part of the circumference of the cap, and a screw thread on the interior of said cap below said liner retaining ledge, the central portion of said thread being of one width and the upper and lower ends of said thread being of less width, to increase the length of the thread with a given length of skirt, the upper end of said thread terminating adjacent the discontinued portion of said ledge.

11. A molded closure cap for a container having a threaded neck or opening, said cap having a threaded inner surface for mating with the thread on the aforesaid container, and a circumferentially extending liner retaining ledge located at the upper end of the thread of the cap, said liner retaining ledge being interrupted to form a breach at a point so related to the thread of the cap that the upper end of the mating container thread may pass through and into the liner receiving space above said ledge.

12. A liner recess closure cap for a container having a threaded neck or opening, said cap being made directly in finished form by a single molding operation out of a synthetic resin composition which during the final stages of the molding operation is somewhat elastic and thereby adapted to be removed from a molding pin despite interlocking of the molding pin with the liner recess, said cap having an inner surface molded to provide a thread mating with the thread on the aforesaid container and a vacant liner recess defined by a liner retaining ledge located at the upper end of said thread of the cap, said recess serving to receive and retain a separate sealing liner in place within-the cap, said liner retaining ledge being interrupted to form a breach at a point so related to the thread of the cap that the upper end of the mating container thread may pass through the liner retaining ledge.

13. A liner recess closure cap for a container having a threaded neck or opening, said cap being made directly in finished form by a simple molding operation out of a phenolic condensation product which during the final stages of the molding operation is somewhat elastic and thereby adapted to be removed from a molding pin despite interlocking of the molding pin with the liner recess, said cap having an inner surface molded to provide a thread mating with the thread on the aforesaid container, a liner recess defined by an interrupted liner retaining ledge located at the upper end of said thread of the cap, and a yieldable lin'er held in place by said retaining ledge, said retaining ledge having a breach at a point so related to the thread of the cap that the upper end of the mating container thread may pass through the ledge and into contact with the liner above the ledge.

14. As an article of manufacture, a closure cap comprising the combination of a cover part, an

vintegral depending skirt, a screw thread in said skirt, and a liner retaining ledge above said screw thread extending partially about the circumference of the cap, said' ledge being discontinued for a part of its length adjacent the upper end of the thread to receive the upper end of a thread on a container.

I LOUIS A. VON TILL.

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