HK1165366A - Method for closing a metallic container - Google Patents

Description

Method for closing a container formed from sheet metal

Technical Field

The present invention relates to a method for providing an upper closure of a container formed of sheet metal, such as a closed tub or other container, comprising a peripheral side wall having a cylindrical shape or an inverted and slightly frustoconical shape, and having an upper end portion and a lower end portion to which respective end walls are connected.

Background

The upper and lower end walls of the container of the type considered here are double-seamed, respectively and peripherally, in the upper and lower ends of the peripheral side wall, the upper end wall being provided with a substantially eccentric opening having a profile substantially smaller than that of the peripheral side wall, and with a gripping handle contained in the interior of the axial projection of the profile of the container, so as to allow the container to be lifted by the gripping handle connected only to the upper end wall. The opening arranged on the upper end wall is configured to define a seat to which a lid, substantially formed of plastic material, is applied.

These double seaming stages in the manufacture of the containers considered herein are rarely performed in product filling equipment due to the complexity of the double seaming process which requires the use of specialized and often expensive equipment.

Thus, the container is closed in the manufacturer's facility by double seaming the end walls to the peripheral side walls of the container and then transported to a facility for filling with the product to be commercialized. Since the containers are transported with the end walls already double-seamed to the peripheral side walls, they cannot be fitted one inside the other, need to be arranged side by side and stacked in transport vehicles and in storage sites, and, at the container manufacturer and at the filling plant, need physical spaces presenting undesirably large volumes with respect to the mass of the material, considerably increasing the transport and storage costs and requiring special care in transporting these containers.

Another drawback of these containers, brought about by the filling operation performed with the end walls already connected (usually by double seaming), arises from the fact that: filling can only be performed through a reduced size opening arranged in the upper end wall. Thus, as occurs in the case of filling containers closed above by a removable lid and provided with a suspension handle applied to the peripheral side wall but not to the lid, the time taken to fill the product is longer than that corresponding to performing the filling without the upper end wall.

In order to overcome the above inconvenience, the present applicant has proposed the constructive solution object of brazilian patent application PI 0804305-1, "contact IN METAL SHEET", filed on 9.10.2008. In this prior art solution, the upper end wall can be easily, quickly, reliably and hermetically fixed to the peripheral side wall of the container by the filling machine of the product, without the need for a double seaming operation.

According to said prior art constructive solution of the same applicant, the upper peripheral edge of the peripheral side wall and the outer peripheral edge of the upper wall are shaped so as to allow them to be reliably and hermetically fixed to each other by means of a simple and simultaneous deformation operation to be performed by the filling machine (generally by means of an elastic sealing element in the form of a gasket compressed between the deformed edges of the peripheral side wall and the upper wall).

In applications where a high degree of axial retention is required between the upper wall provided with the suspended handle and the peripheral side wall of the container, the upper end portion of the peripheral side wall and the peripheral upper skirt of the upper end wall are provided with one or more circumferential ribs and grooves which cooperate with each other in the condition of fitting the upper end wall in the interior of the upper end portion of the peripheral side wall.

Although the provision of circumferential ribs and grooves results in a significant improvement in the degree of axial retention of the upper end wall and in the degree of airtightness in said upper closure of the container, these ribs and grooves are provided separately in the skirt of the upper end wall and in the peripheral side wall of the container by the manufacturer of the container, with undesirable dimensional precision being required in the manufacture of these two parts in order to allow them to be fitted at the final closure of the container and to obtain the desired degree of axial retention and further sealing. Although this prior art solution provides the advantages mentioned in said prior art patent application of the same applicant, it has the inconvenience of requiring a costly manufacturing procedure.

Disclosure of Invention

Due to the above inconveniences with respect to the prior art solutions, the object of the present invention is to provide a method for closing a container formed of sheet metal, having a peripheral side wall, a lower end wall and an upper end wall provided with a small discharge opening and with a suspended handle, and which can be easily, quickly, reliably and hermetically fixed to the peripheral side wall by a filling machine of the product to be packaged, without requiring double seaming operations or costly operations for integrating the peripheral side wall and the upper end wall with reduced dimensional tolerances.

The method is suitable for closing a container formed of sheet metal of the type comprising a tubular body formed by a peripheral side wall having an upper end and a lower end to which respective upper and lower end walls are attached.

According to the invention, the closing method comprises the following steps: a tubular body of sheet metal material is formed, the upper and lower end portions of which are shaped so as to be provided with an upper retaining hook and a lower retaining hook, respectively, which are normally double-seamed to the lower end wall.

The upper end wall is conformed in sheet metal so as to provide a peripheral upper skirt, the end edge of which is bent to configure an upper closure hook when the container is closed on top, still empty or already filled with product.

The upper closure hook and the upper retaining hook and the peripheral upper skirt of the upper end wall and the upper end portion of the peripheral side wall are then deformed together so as to provide seaming of said hooks upon compression of the intermediate elastic sealing element, and the deformation of at least one of the peripheral upper skirt and the corresponding inner peripheral retaining groove in the upper end portion of the peripheral side wall causes the retaining rib to fit tightly.

The closing method proposed by the present invention allows the upper end wall to be hermetically and reliably seamed to the tubular body of the container without the need for costly and complex double seaming operations or the pre-formation of retaining ribs and grooves with costly dimensional tolerances that hamper the manufacture and increase the cost of these containers.

With the proposed method, the container can be manufactured without retaining ribs and grooves and transported to be filled with the upper end wall still acting as a separate piece but with the lower end wall already suitably double-seamed to the tubular body.

In the proposed solution, the entire cross section of the upper end portion, still open, can be used during filling, reducing the operating time before the operation of fitting and retaining the respective end wall in the interior of the peripheral side wall by means of simple and concomitant axial and radial compression operations, to provide the deformation of the closing hook and of the upper retaining hook and the concomitant deformation of the circumferential ribs and grooves.

In the case where the peripheral side walls are configured to taper in a continuous or stepped manner from one end to the other (typically from the upper end to the lower end), the containers can be stored and transported without the upper end wall and in a condition where they remain partially fitted one inside the other in a stacked manner, allowing significant storage and transport volume economy until they are closed at the filling device and preferably after the filling operation.

Drawings

The invention will be described below with reference to the accompanying drawings, given by way of example of one embodiment of the invention and in which:

FIG. 1 shows a top plan view of a container of the present invention having a peripheral sidewall with a circular profile;

FIG. 2 shows a partial diametrical section of the container showing the upper and lower end walls secured to the peripheral side wall, said section being taken according to line II-II in FIG. 1;

FIG. 3 shows an enlarged, exploded detail of the area of FIG. 2, showing the assembly of the upper end wall in the upper end portion of the peripheral side wall, showing the shape of the component parts prior to seating of the upper end wall onto the peripheral side wall;

FIG. 4 shows the same detail of FIG. 3, but showing the upper endwall already seated and only temporarily retained to the peripheral sidewall;

FIG. 5 shows a reduced side view of the container shown in FIG. 4 when a seaming assembly is applied thereto for compressing the closure hooks and the upper retention hooks to form the axial retention ribs and grooves;

FIG. 5A shows a view similar to FIG. 4 but showing the simultaneous deformation of the application of the seaming means to provide a closure hook and an upper retention hook and the simultaneous deformation of the peripheral upper skirt together with the upper end of the peripheral sidewall to form a circumferential rib and groove to be tightly fitted together;

FIG. 6 shows a view similar to FIG. 5, but only showing the container; and is

Figure 7 shows a partial diametrical section view of two containers constructed in accordance with the method of the invention with the upper end wall removed and one partially assembled into the other.

Detailed Description

The closing method of the invention is suitable for containers formed of sheet metal, typically tin plate, and which comprise a tubular body C formed by a peripheral side wall 10, having any polygonal cross section, typically circular, and having an upper end portion 10a and a lower end portion 10b, in which respective upper 20 and lower 30 end walls are fixed.

According to the invention, after the sheet metal part has been conformed to form the tubular body C, the latter is operated so as to reshape the upper end 10a and the lower end 10b of the peripheral side wall 10.

The shaping of the upper end portion 10a is carried out so as to provide therein an upper peripheral edge 10c which is bent outwards and downwards, defining an upper retaining hook 11 having an approximately inverted U-shaped profile.

In a preferred form of the invention, the upper retaining hook 11 is shaped to provide an inner leg 11a defined by a portion of the upper end 10a of the peripheral side wall 10, an arcuate base leg 11b and an outer leg 11c converging with respect to the inner leg 11 a. The reshaping of the lower end 10b of the peripheral side wall 10 is carried out to provide a lower peripheral edge 10d which is bent outwardly to define a lower retaining hook 12 which may have any known prior art configuration to allow the fixing (for example by double seaming) of the likewise reshaped peripheral edge of the lower end wall 30, also made of sheet metal and having any conventional configuration. The solution for reliably and hermetically fixing the lower end wall 30 to the tubular body C is not a particular aspect of the method, which fixing may be performed at the manufacturer's plant by any suitable method.

After reshaping the tubular body C and the upper and lower retaining hooks 11, 12, the peripheral edge of the lower end wall 30 is fixed to the tubular body C, typically by double seaming.

With the formation of the tubular body C and the closure of its lower end wall 30, the sheet metal portion is shaped to define an upper end wall 20 comprising an intermediate panel 21, which may optionally be provided with a reinforcing circumferential ridge of the well-known prior art, and with a peripheral upper skirt 22 projecting axially outwards, and which is configured to fit tightly, with interference, in the interior of the upper end 10a of the peripheral side wall 10.

The peripheral upper skirt 22 has an end edge 22c which is bent outwardly, downwardly and inwardly so as to define a closure hook 23 having an approximately inverted U-shaped profile.

In the preferred and illustrated form, the closure hook 23 is shaped to provide an inner portion 23a defined by the upper portion of the peripheral upper skirt 22 of the upper end wall 20, an arcuate base portion 23b and an outer portion 23c which converges with respect to the inner portion 23a and internally includes an upwardly projecting end flange 23 d.

According to the method of the invention, the peripheral upper skirt 22 of the upper end wall 20 can then be fitted and seated in the interior of the upper end 10a of the peripheral side wall 10, with the container empty or already filled with product, said fitting being carried out to seat the closing hook 23 on the upper retaining hook 11, sandwiching the previously provided elastic sealing element 40 between said hooks 23, 11. (see FIGS. 4, 5A and 6).

In the solution shown in the figures, the fitting of the closure hook 23 onto the upper retaining hook 11 is carried out such that the arcuate base portion 23b of the closure hook is seated on the arcuate base leg 11b of the upper retaining hook, an elastic sealing element 40, for example a plastisol film, being arranged between said arcuate base portion 23b and the arcuate base leg 11 b.

As shown, the elastic sealing element 40 is preferably applied under the arcuate base portion 23b of the closure hook 23 so as to be seated on the arcuate base leg 11b of the upper retaining hook 11 when the upper end wall 20 is fitted and seated in the interior of the upper end portion 10a of the peripheral side wall 10.

The exploded view of fig. 3 shows the shape imparted to the parts prior to closing the container. At this stage, the diameter of the free end edge of the outer leg 11c of the upper retaining hook 11 is slightly smaller than the diameter of the free upper edge of the end flange 23d projecting obliquely upwards and outwards. Thus, when the upper end wall 20 is seated in the condition shown in fig. 4, both said portions undergo elastic deformation to allow the end flange 23d to fit under the free end edge of the outer leg 11c of the upper retaining hook 11.

In preparation for closing the container, normally after having been filled with the product to be packaged, with the upper end wall 20 already fitted and seated in the interior of the upper end portion 10a of the peripheral side wall 10, the facing areas of the closure hook 23 and the upper retaining hook 11, and of a portion of the peripheral upper skirt 22 and of the upper end 10a, can be subjected to a joint deformation operation, so as to provide a seaming of the closure hook 23 onto the upper retaining hook 11, the elastic sealing element 40 is compressed therebetween, and further forms at least one outer circumferential retaining rib 24 in the peripheral upper skirt 22 and one inner circumferential retaining groove 14 in the upper end portion 10a of the peripheral side wall 10, the retaining hook 24 being tightly fitted in the interior of the retaining groove 14, a tight and reliable coupling is ensured between the parts of tubular body C and upper end wall 20, without particular manufacturing care being required, in order to allow retaining rib 24 to perfectly follow the internal contour of retaining groove 14.

The deformation of the closure hook 23 and the upper retention hook 11 is obtained by: an inward and upward radial force is applied to the peripheral upper skirt 22 and the upper end 10a of the peripheral side wall 10, as opposed to an outward radial force, so as to simultaneously form the retaining rib 24 and the retaining groove 14.

In the preferred and illustrated construction, the fitting of the closure hook 23 onto the upper retaining hook 11 is made such that the arcuate base portion 23b of the closure hook 23 rests on the arcuate base leg 11b of the upper retaining hook 11, and the crimp of the closure hook 23 onto the upper retaining hook 11 is also made such that the inner, arcuate base portions 23a, 23b and outer portions 23c of the closure hook 23 rest on the inner, arcuate base legs 11a, 11b and outer legs 11c, respectively, of the upper retaining hook 11, compressing the resilient sealing element 40 and causing the end flange 23d to project upwardly between the outer and inner legs 11b, 11a of the upper retaining hook into the interior of the upper retaining hook 11.

As shown in fig. 5 and 5A, the deformations for seaming the hooks and for forming the retaining ribs 24 and retaining grooves 14 can be easily performed after filling of the product by means of a seaming device 50 comprising a plurality of outer peripheral fingers 51 and a plurality of inner peripheral fingers 52, said outer peripheral fingers 51 and inner peripheral fingers 52 being configured to jointly define a circular alignment having a variable diameter depending on the operation of the seaming device 50 and to simultaneously act on the hooks from the outside of the container and on the peripheral upper skirt 22 so as to simultaneously produce seaming deformations of the upper closing hooks 23 and the upper retaining hooks 11 and deformations of the retaining ribs 24 and retaining grooves 14. As can be noted in fig. 5A, the outer peripheral fingers 51 and the inner peripheral fingers 52 are configured to exert the desired reshaping of the respective portions on which they are seated to obtain the seaming of said hooks and the fitting between the peripheral upper skirt 22 and the upper end 10a of the peripheral side wall 10, in addition to forming a sealing area other than that defined by the seaming of the closing hooks 23 and the upper retaining hooks 11, between which the elastic sealing element 40 is arranged, also ensuring a strong axial retention between the upper end wall 20 and the tubular body C of the container.

As also shown, after completing the deformation of the closing hook 23 and the upper retaining hook 11, the outer leg 11c of the upper retaining hook 11 and the outer portion 23c of the closing hook 23 present a substantially rectilinear and downwardly and radially inwardly inclined profile, ensuring a strong, reliable and tight fixation of the upper end wall 20 to the peripheral side wall 10.

To facilitate the adaptation of the two portions to be fixed to each other, and the operation of plastic deformation of the sheet metal at the initial and final formation of the two hooks, the inner leg 11a of the upper retaining hook 11 and the inner portion 23a of the closing hook 23 are initially shaped to present a profile that is substantially rectilinear and slightly inclined upwards and radially outwards.

According to the illustrated embodiment, the retaining rib 24 and the retaining groove 14 are configured to provide a cross-section having the approximate shape of a rounded V with a convex arc and a concave arc, respectively.

Depending on the nature of the application of the elastic sealing element 40, a portion of its extension may penetrate and be compressed between the inner leg 11a of the upper retaining hook 11 and the inner portion 23a of the closure hook 23, as shown in fig. 5.

Considering that the construction of the container of the invention aims to obtain a closure that is easy to implement but able to comply with the safety requirements of the containers applied to dangerous products, the peripheral side wall can be provided with energy absorption means that absorb energy by controlled plastic deformation. Thus, the peripheral side wall 10 may have two regions adjacent to the upper end 10a and the lower end 10b, respectively, each region occupying about 10% to 15% of the height of the peripheral side wall 10 and being shaped in a plurality of circumferential grooves 10e providing the profile of the shape of a lying V with rounded vertices. These regions have a pleated structure which tends to deform before excessive deformation of the container occurs in the region where the end walls 20, 30 are secured to the peripheral side wall 10.

As can be observed in fig. 1 and 2, considering that the two upper 20 and lower 30 end walls are fixed to the peripheral side wall 10 in a non-removable manner, the intermediate panel 21 of the upper end wall 20 is provided with a substantially eccentric opening 21a of smaller diameter, and with a grip handle 60 arranged substantially in the central region of said upper end wall 20, this grip handle 60 being integrally fixed in said upper end wall 20 so as to allow the container to be lifted by said grip handle 60 even in the event of filling. In this type of construction, the smaller diameter opening 21a is normally closed by a removable lid, preferably constructed of plastic material and not shown here since it does not form part of the invention.

As already mentioned before and further shown in fig. 7 of the drawings, the peripheral side wall 10 of the container may be configured to allow a partial telescopic fit between two stacked containers. In the illustrated embodiment, the peripheral side wall 10 has an inverted and slightly frustoconical shape, the smaller base coinciding with the lower end wall 30 and the larger base preferably lying in a plane axially spaced back with respect to the mounting plane of the upper end wall 20, and the peripheral side wall 10 being deformed in this plane to define the outer circumferential projection 19.

By this configuration, the container can be telescopically fitted inside another inferiorly disposed container, with the upper end wall removed, this fitting, as shown in fig. 7, being carried out until the outer circumferential projection 19 rests on the free edge of the upper end portion 10a of the peripheral side wall 10 of the inferiorly disposed container, allowing the total volume occupied by the containers thus stacked to be significantly less than the volume that would be occupied by the same number of inferiorly and superiorly closed containers stacked one on top of the other. By means of this partial assembly arrangement, the containers can be stored and transported in a voluminous and therefore cost-intensive manner.

Although only one embodiment of the invention has been illustrated herein, it should be understood that the present closing method can be subject to variations of the deformation characteristics of the parts involved, without departing from the constructive concept defined in the claims that accompany the present specification.

Claims (7)

1. A method for closing a container formed from sheet metal, said container comprising a tubular body (C) formed by a peripheral side wall (10) having an upper end portion (10a) and a lower end portion (10b), to which an upper end wall (20) and a lower end wall (30) are respectively fixed, characterized in that it comprises the steps of:

-partially reshaping a metal sheet to define a peripheral side wall (10) of said tubular body (C);

shaping said peripheral side wall (10) so as to provide, in its upper end (10a), an upper peripheral edge (10c) and, in its lower end (10b), a lower peripheral edge (10d), said upper peripheral edge being bent outwards and downwards defining an upper retaining hook (11) having an inverted U-shaped profile, said lower peripheral edge being bent so as to define a lower retaining hook (12);

-fixing the lower end wall (30) peripherally to the lower retaining hook (12) of the tubular body (C);

-shaping a metal sheet portion to define an upper end wall (20) having an intermediate panel (21) and a peripheral upper skirt (22) having an end edge (22c) bent outwards, downwards and inwards so as to define an upper closure hook (23) having an inverted U-shaped profile;

-fitting and seating the peripheral upper skirt (22) in the interior of the upper end (10a) in order to seat the upper closure hook (23) onto the upper retaining hook (11), sandwiching a pre-set elastic sealing element (40) between the upper closure hook and the upper retaining hook (23, 11), in the case where the container is empty or already filled with product; and is

-subjecting simultaneously the facing areas of the upper closure hook (23) and of the upper retaining hook (11) and of a portion of the peripheral upper skirt (22) and of the upper end (10a) to a deforming operation so as to crimp the upper closure hook (23) onto the upper retaining hook (11), compressing the elastic sealing element (40) and forming at least one outer circumferential retaining rib (24) in the peripheral upper skirt (22) and a corresponding inner circumferential retaining groove (14) in the upper end (10a) of the peripheral side wall (10), which inner circumferential retaining groove is tightly fitted with the retaining rib (24).

2. A method as claimed in claim 1, characterised in that said upper retaining hook (11) with inverted U-shaped profile is shaped to provide an inner leg (11a) defined by a portion of the upper end (10a), an arcuate base leg (11b) and an outer leg (11c) converging with respect to said inner leg (11a), said upper closing hook (23) with inverted U-shaped profile being shaped to provide an inner portion (23a) defined by the upper portion of the peripheral upper skirt (22), an arcuate base (23b) and an outer portion (23c) converging with respect to said inner portion (23a) and internally containing an upwardly projecting end flange (23d), the fitting of said upper closing hook (23) onto said upper retaining hook (11) being carried out so that the arcuate base (23b) of said upper closing hook is seated onto the arcuate base leg (11b) of said upper retaining hook (11), the elastic sealing element (40) is arranged between the arcuate base (23b) and the arcuate base leg (11b) and the seaming of the upper closure hook (23) onto the upper retaining hook (11) is carried out so as to place the inner side portion (23a), the arcuate base (23b) and the outer side portion (23c) of the upper closure hook (23) on the inner side leg (11a), the arcuate base leg (11b) and the outer side leg (11c) of the upper retaining hook (11), respectively, compressing the elastic sealing element (40) and causing the end flange (23) to protrude upwardly between the outer side leg (11b) and the inner side leg (11a) of the upper retaining hook into the interior of the upper retaining hook (11).

3. Method as in claim 2, characterized in that the deformation of the upper closing hook (23) and the upper retaining hook (11) is obtained by: -exerting an inward upward radial force on the peripheral upper skirt (22) and on the upper end (10a) of the peripheral side wall (10), in contrast to the application of an outward radial force, so as to form simultaneously the retaining rib (24) and the retaining groove (14).

4. A method as claimed in claim 2 or 3, wherein the outer leg (11c) of the upper retaining hook (11) and the outer portion (23c) of the upper closure hook (23) are each substantially rectilinear and inclined downwards and radially inwards.

5. The method according to claim 2, 3 or 4, characterized in that the inner leg (11a) of the upper retaining hook (11) and the inner side (23a) of the upper closing hook (23) are respectively substantially rectilinear and slightly inclined upwards and radially outwards.

6. Method as in claim 2, 3, 4, 5 or 6, characterized in that a portion of the extension of the elastic sealing element (40) is respectively pierced and compressed between the inner leg (11a) of the upper retaining hook (11) and the inner side (23a) of the upper closing hook (23).

7. The method according to claim 2, 3, 5 or 6, characterized in that the retaining rib (24) and the retaining groove (14) are formed by deforming the metal sheet of the respective portion and have a nearly rounded V-shaped cross-section in the form of a convex arc and a concave arc, respectively.