Technical Field

The invention relates to the field of container lids, and more specifically, container lids comprising a seal.

Background of the Invention

Containers facilitate the transport of a variety of products and whilst they may vary somewhat in their specific dimensions and designs, the majority all comprise a number of key features. A container comprises a main hollow body, in which a product can be inserted. In addition, a container is generally accompanied by a lid, designed specifically to close the opening through which the product to be transported is inserted into the container body.

The container lid is required to ensure that the product cannot escape the container, and thus must be designed such that the lid sufficiently seals said container.

Whilst some containers may be permanently sealed, a desired function of most containers is that the lid can be removed by a user when access to the goods inside is desired. Therefore, the design of the lid and the method by which it is held to the container, whilst secure and with minimal possibility of the lid being removed accidentally, must facilitate access to the user when desired.

Many methods by which lids are secured to a container involve the use of a seal, for example an O-ring. Said seal is designed to form a contact point between the lid and the rim of the container. When a force is applied, forcing the lid and container towards each other, the seal is compressed and a sufficient surface contact between the seal and both the container and lid is established, thereby ensuring no gaps are present where the lid and container meet. Often, seals such as these are attached to the lid, such that an additional component is not required to be kept separately. This reduces the workload when sealing the container and ensures the seal is positioned correctly.

One field in which container lids are essential, is the field of industrial packaging. Containers are provided wherein they may be used for the transport of goods over a large distance. An example of these containers are the well recognized steel or plastic "drums", for example those sold by Greif. These drums tend to be categorized into two types, tight head drums, which feature a permanently secured lid, and open head drums, which feature a removable lid, and are better suited for situations in which easy access to the contents is required often, or when the contents are solid and thus cannot be poured through a small opening in the lid.

The standard open head drum and lid are held together via a ring that wraps around the circumference of the meeting point between the lid and the drum. The ring is then tightened, and the compressive force, usually aided by grooves in the lid and a pronounced rim of the container, holds the two components together.

A requirement for such a system to work is that the lid is formed with a lip, which can hold the solid seal, wherein the lip comprises an opening such that the container rim may slot inside, making contact with the seal. The lip therein generally forms an arch.

It is necessary to ensure the seal is securely held in the lip and may not fall out. As seen in the prior art solid seals are held inside the lip of these container lids by means of an adhesive material, which is preapplied to the seal prior to its insertion into the lid lip, as shown in Fig. la.

Problems to be Solved bv the Invention

The container lids as seen in the prior art, require an adhesive to be applied to the seal such that it may be held in position within the lid lip. The use of an adhesive has a number of significant drawbacks.

Firstly, often the adhesive used to hold the seal in place has harmful properties meaning that great care must be taken to ensure it is applied safely, usually requiring workers to wear protective equipment.

This may also require extra steps to be taken, including heating of the adhesive prior to application, which induces further safety risks whilst simultaneously increasing complexity and costs.

Another significant issue with the use of an adhesive to secure the seal is that the toxicity of the adhesive prevents the container from being used for the transportation of food. This therein significantly restricts the potential uses of the container, especially as open head drums are often used for the transportation of food, due to the requirement of a large opening through which to insert and remove solid food items.

The general shape of the lids currently seen in the prior art also leads to a further problem. When the seals are not present within the lip of the lid (either prior to insertion, or after removal), the arch shape allows for the lids to easily stack upon one another, as seen in Fig. lb. The upper side of one arch may fit neatly in the lower side of an arch of another lid, allowing for a large amount of surface contact between the two lids. This is generally not desirable as the lids easily become stuck to one another and are difficult to separate.

This may lead to users stacking lids in an alternating manner i.e. the first lid is face-up, the second lid is face-down etc... This deems the stack unstable, and can lead to the lids being damaged when not in use.

Thus, it is an object of the present invention to provide a container lid in which a seal may be held without the use of an adhesive, preferably in a manner that prevents the sticking of lids to one another during storage. In addition, another object of the present invention is to provide a method of manufacturing such a lid.

Summary of the Invention

A container lid according to the present invention comprises a central region bounded by a perimeter region, wherein the edge of the perimeter region has a curled lip defining a cavity extending around the perimeter of the lid. The opening giving access to this cavity has a width, which is equal to, or narrower than, the largest cross sectional width of the cavity.

The cavity of the lid lip may hold a seal. The seal may comprise a cross section diameter greater than the width of the cavity opening. Therefore, once inserted into the lip of the lid, the seal may be held in place simply by the structure of the lid lip, as the seal shall be wider than the opening. This may prevent the seal from being separated from the lid

unintentionally. The seal may have a substantially uniform cross section such that the cross section diameter is the same from a variety of different angles. For example, the seal may have a circular cross section. The shape of the lip may allow the seal to be held in the lip without the need for any additional fixing means. This means that the seal may not be "attached" to any surface of the lid. An adhesive may not be required for ensuring the seal is held in the lip.

Due to the narrow opening, the seal may not be removed by hand. The removal of the seal may thus require a specialized tool or apparatus, specifically designed for removal of the seal. This tool may force the seal towards the opening, and apply a force sufficient for compressing the seal such that the seal cross section diameter in one axis is reduced to the width of the opening or smaller.

The lid may also comprise a groove located closer to the centre of the lid than the lip. Said groove may allow the depth of the container lip to be accentuated, thus allowing easier positioning of the lid onto a container when in use. The groove may also provide a suitable well in which part of a ring clamp may rest when the ring clamp is used to secure the lid to the container. The groove may be a smooth "U" shape.

The cavity opening may be wide enough to receive the rim of a container. The majority of lids are designed with the dimensions of the container known. This allows the lid to be designed such that it fits on the container and performs its desired function. The lid of the present invention may be designed such that the cavity opening is as wide, or wider, than the thickness of the rim of the container the lid is designed to fit. The opening may allow for said container rim to make contact with the seal when the seal is positioned within the lip.

The lip may be rounded such that at least part of the lip forms an arc with an approximately circular cross section. The lip may be rounded such that at least part of the lip is curved to form at least that of a semi-circle. The curvature of the lip may be 180 degrees or more.

The lip may comprise a skirt portion. Said skirt portion may be defined as a part of the lip extending to the very edge of the lid. This skirt may comprise a substantially straight portion. Alternatively the skirt may be rounded.

In addition, the invention further comprises a method for producing said container lid, wherein the method includes a pressing step, wherein a workpiece is pressed between a plurality of dies to from a lip on the perimeter edge of the workpiece, and a deforming step wherein the lip of the workpiece is curled inwards to form a cavity such that it's opening has a width which is equal to, or narrower than, the largest cross sectional width of the cavity. The deforming step may comprise the workpiece being pressed between multiple dies. These dies may be shaped such that when they are brought together, a gap is present between them. Said gap may possess the shape of the desired lip cross section. Thereby when the workpiece is placed between the dies and the dies are pressed towards one another, the workpiece is deformed such that it forms the shape of the gap formed between the dies.

Said deforming step may comprise the workpiece being pressed radially between multiple dies as seen in Figs. 4 and 6. The radius of the lid may then be reduced. The outer edge of the lid may be compressed such that it no longer forms the part of the lid furthest from the centre.

The deforming step may also comprise subsequently pressing the workpiece axially between multiple dies, as seen in Fig. 5. Axially may describe the axis in which the lid would be placed atop a container i.e. perpendicular to both the radial and circumferential axis. Said pressing may allow the outer edge of the workpiece to be pressed inwards towards the cavity. This may provide the lip with a substantially rounded skirt.

The plurality of dies may be positioned such that the entire perimeter of the lid lip is pressed simultaneously, as seen in Fig. 8.

Alternatively the deforming step may comprise the rotation of the lid such that the perimeter edge is pressed gradually over one or more rotations, as shown in Fig. 7. The centre of the lid may be secured and the lid spun such that the circumference of the workpiece may be gradually deformed. The lid may be rotated multiple times such that the deformation at each part of the circumference is only minor, thereby preventing any unwanted deformation which may occur through pressing parts of the circumference piece by piece.

The pressing may be performed by a rolling member, which may rotate on a parallel axis to the lid's rotational axis. The rolling member may rotate whilst performing the pressing of the lid. The rolling member may aid in allowing the lid to continue rotating whilst the pressing is performed, further enabling the deforming step to be smooth. Should the workpiece be made of plastic the rolling member may be heated to facilitate bending of the lip. Alternatively, the workpiece may be heated prior to pressing by the rolling member.

Advantages of the present invention

In the present invention, as the seal is held in place by the shape of the lip, and thus is prevented from falling out of the lip, an adhesive is not needed. The absence of the adhesive thereby renders the container suitable for the transportation of food products.

In addition, removal and replacement of the seal can be performed without risk of damage to the seal or lip, as adhesive no longer sticks to the surfaces of the seal and lip.

Furthermore, the shape of the lid prevents lids from fitting into one another during storage. This results in far easier removal of the lids from one another when stacked as the only point of contact between stacked lids is at the outer rim, as seen in Fig. lc.

The lip shape of the present invention may lead to the lid having a smaller diameter than the lids seen in the prior art. This may allow for the length of seal material to be reduced, as the seal may not be required to extend around as large a perimeter as that of the prior art. A smaller closing ring may also be required. The present invention may therefore allow for a reduction in materials (and thus costs) for these additional components.

In addition, the present invention comprises a structure in which a seal can be secured in place without requiring any adhesive, which could comprise harmful chemicals, and may require further heating and applying steps. The invention therefore provides the opportunity for a simpler, safer, seal instillation.

Brief description of Drawings

Figure la shows a cross section of a lip of a lid with a seal held by an adhesive, as outlined in the prior art. Figure lb shows a cross section of multiple lids of the prior art stacked upon one another.

Figure lc shows a cross section of multiple lids according to the second embodiment of the present invention.

Figure 2 shows a cross section of a lip of the lid with a seal, according to the first embodiment of the present invention.

Figure 3 shows a cross section of a lip of the lid with a seal, according to the second embodiment of the present invention.

Figure 4 shows a radially pressing method step according to the present invention.

Figure 5 shows an axially pressing method step according to the present invention.

Figure 6 shows a radially pressing method step according to the present invention.

Figure 7 shows an overhead view of a pressing step according to the present invention wherein the lid is rotated.

Figure 8 shows an overhead view of a pressing step according to the present invention.

Modes for Carrying out the Invention

Embodiment 1

In Fig. 2, an example of a container lid according to Embodiment 1 of the invention is shown. Fig. 2 is a cross sectional diagram of the lip found in the perimeter region of the container lid. It clearly shows the shape of said lip, and the cavity which is defined by the shape of the lip. The container lid may be formed of a single shaped piece. The lid may be made, at least partly, of metal or plastic.

The lid comprises a central region 10 which extends radially outwards. Extending radially outwards, and surrounding the central region 10 a perimeter region is present. The central region 10 may be substantially flat, extending horizontally when viewed in a cross section. The perimeter region may comprise a groove 12 at a section of the perimeter region positioned closest to the central region 10. This groove 12 may extend below the central region 10, when viewed in a cross section. The groove 12 may be considered to comprise a curved "u-shaped" well. The groove 12 may be defined as starting at the point at which the lid begins to curve, and finishing at the point at which the lid becomes level with the central region 10 again.

This groove 12 may serve to allow for a securing means to grip the container lid to ensure the container lid is secured, when the lid is placed atop a container. It should be noted that the lid may not comprise a groove 12 one is not required for securing the lid to the container.

The perimeter region may further comprise a lip extending from the outer most point of the groove 12 and initially extending radially outward. The lip may be defined as starting at the point at which the groove 12 ends by becoming level with the central region 10, and may be defined as ending at the perimeter edge of the lid.

The lip may comprise a curl section and a skirt section, referred to as the curl 14 and skirt 16 herein. The curl 14 may be defined as the portion that connects to the end of the groove 12. The skirt 16 may be defined as the portion extending from the curl 14 to the outer edge.

The curl 14 may extend upwards above the central region 10, when viewed in a cross section, initially in a straight manner, before curving outwards such that it forms a substantially circular segment.

The skirt 16 may be bent such that the outermost edge of the lip points downwards, but also slightly inwards towards the central region 10. The skirt 16 may comprise a bent portion which serves to angle the skirt 16 inwards, and a straight end portion which extends in a substantially straight manner.

The straight end portion of the skirt 16 may run substantially parallel to, or angled towards the straight portion of the curl 14. The curvature of the lip may thus extend around 180 degrees or more, of a circle. The lip defines a cavity which may extend around the perimeter of the lid. The cavity may comprise an opening which may be equal to, or narrower than, the largest cross sectional width of the cavity. This ensures that any seal 18 which also comprises an equal, or larger, cross sectional width as the largest cross sectional width of the cavity, will be prevented from falling out as the opening will be narrower, or equal to said cross sectional width of the cavity.

The opening may be narrower than the largest cross sectional width of the cavity, and thus the seal 18 would be required to be compressed during removal and/or insertion. As it generally requires a large amount of force to compress a typical seal, the force of gravity will be insufficient to compress and pull the seal 18 out of the cavity. In addition, the opening may be equal to the largest cross sectional width of the cavity, and may keep the seal 18 in the cavity due to the frictional force between the seal 18 and the cavity being greater than the gravitational force acting upon the seal.

The seals may therefore be held in mechanically, and not via any additional fixing means.

The cross sectional shape of the seal 18 may be designed specifically to fit the dimensions of the lip cavity. Specifically, the seal 18 may be designed such that is has a cross sectional width greater than the width of the opening. The seal 18 may have a cross sectional width that it equal to, or greater than, the largest cross sectional width of the cavity.

When the seal 18 is positioned inside the cavity, a specialized tool is needed to facilitate removal of the seal. The specialized tool may allow the seal 18 to be compressed and removed from the cavity through the opening.

Method:

The production of a lid comprises a plurality of steps. Firstly a pressing step may be performed. The pressing step comprises the lid being held between an upper and lower die, whilst a compressive force is applied. The lid may be deformed such that the groove and a lip is formed.

The curling process is defined as a deforming step and may comprise one or more pressing steps; including a radially pressing step. The deforming step may be performed when the lid is positioned upside down, i.e. such that the surface intended to form the external top side of the lid is oriented on the bottom during the deforming step.

The radially pressing step comprises the lip being pressed radially inwards. The lid is positioned between a plurality of dies 40, 42, 48 which are pressed towards each other, as seen in Figs. 4 and 6. The radially pressing step may substantially curl part of the lid. The skirt portion may remain substantially straight.

The method steps above may describe the production of a lid made of metal; however, the skilled person would recognize that the production steps may be adapted for the production of a plastic lid. For the production of a plastic lid, the pressing steps may include one or more heating steps such that the workpiece is in a state suitable for bending without the workpiece breaking. Alternatively or additionally, pressing steps may involve production tools such as dies being heated.

Embodiment 2

In Fig. 3, an example of a container lid according to Embodiment 2 of the invention is shown. Fig. 3 is a cross sectional diagram of the lip found in the perimeter region of the container lid. It clearly shows the shape of said lid, and the cavity which is defined by the shape of the lip.

Unless otherwise described, the components of embodiment 2 may be considered identical to those of embodiment 1.

The skirt 16 of embodiment 2 differs from that of embodiment 1 in the following manner. The skirt 16 of embodiment 2 may be formed of a single bent portion. The skirt 16 may be bent such that it is substantially curved from the start of the skirt 16 to the outer edge. The skirt 16 may be bent such that the curl 14 and skirt 16 form a significantly circular shape. The lip of embodiment 2 may therein be formed such that when the seal 18 is inserted into the lip, the lip may thus be deemed to "wrap around" the cross section of the seal. Due to the circular shape of the lip, the lip may contact a greater surface area of the seal 18 than seal lids seen in the prior art. This allows the seal 18 to be held more securely and reduces the chance of any impact with the lid dislodging the seal 18 such that it becomes free from the lip lid.

Method:

Unless otherwise described, the method steps of embodiment 2 may be considered identical to those of embodiment 1.

The curling process is defined as a deforming step and may comprise two or more pressing steps; a first radially pressing step, as seen in Figs. 4 and 6, and an axially pressing step, as seen in Fig. 5. Alternatively, the deforming step may comprise only a single axially pressing step.

The axially pressing step may comprise the lip being pressed axially inwards. This may curl the skirt such that it is substantially curved, preferably circular. This may involve the lid being positioned between a plurality of dies, a lower die which the lid rests upon, and an upper die which may be brought downwards to provide a compressive force to the lid lip.

Possible modifications

The container lid may be formed of a single shaped piece, or alternatively, the lid may be formed of multiple sections joined together by a fixing means.

Whilst the lip has been described having a somewhat circular shape, any shape which may hold a seal 18 securely would be deemed suitable. For example the curl 14 and skirt 16 portion may form a substantially triangular shape.

Additionally, it is noted that the lid may comprise the lip as disclosed in embodiment 1 and embodiment 2, formed around the entire circumference of the lid. The cross sectional shape of the lid around the perimeter may thus be constant around the entire edge of the lid.

Alternatively, the lid may comprise the lip as disclosed in embodiment 1 and embodiment 2, formed around only parts of the circumference of the lid. There may be thus be portions of the lid that do not comprise these circumference of the embodiments 1 and 2 around the perimeter. Two or more segments of the lid lip which have been formed as embodiments 1 and 2 may be sufficient to ensure the seal is held in place securely. Whilst the method for forming the lip of lids of embodiments 1 and 2 have previously shown the lip being curved in the pressing step, prior to a deformation step. It should be noted that the lip may be substantially flat, preferably completely flat, after the pressing step. The deformation step may therein deform the lip from a flat shape to the finished curled or bent shape as seen in embodiments 1 and 2. This deformation may be performed by a profiled rolling member and deforms the lip whilst the lid is rotated.

In addition, whilst the method for forming the lids of embodiments 1 and 2 have been outlined in that the radial pressing step may comprise a rolling member, the axial pressing as seen in Fig. 5 may also comprise a rolling member. The lid may be supported underneath whilst being rotated, and a rolling member may be brought into contact with the lip from above, thereby steadily deforming the lip. The rolling member may have a shaped profile or alternatively the rolling member may have a flat inclined profile.

List of reference numerals

10 Central region

12 Groove

14 Curl

16 Skirt

18 Seal

20 Adhesive

40, 42, 44, 46, 48 Dies

50 Rolling member