FOOD OR BEVERAGES CONTAINER BODY AND FORMING METHOD

Abstract: A container body (10) for food or beverages has a peripheral wall (12), a top opening (14), and a re-entrant shaped base member (16). The base member (16) defines external cavity (20) which extends within the peripheral wall (12). The container body (10) is made from a sheet of metal by appropriate drawing, redrawing, wall lining and rolling processes such that it has a unitary construction. The container body (10) has the same external dimensions as conventional beverage or food cans so that it can be filled and processed on conventional filling lines. The provision of a container body (10) of unitary construction reduces the number of operations in the manufacturing process whereby the cost of manufacture of the container is reduced. The external cavity within the container can be used to enable a self-heating or self-cooling container to be produced.

Description: FOOD OR BEVERAGES CONTAINER BODY AND FORMING METHOD The present invention relates to a container for food or beverages, to a container body for such a container, and to a method of forming such a container body. WO96/29255 describes self-heating and self-cooling containers for beverages. The container described has the same external dimensions and shape as a conventional beverage can, but the base is shaped to define an external cavity extending along a major part of the length of the container, within its peripheral wall, for the receipt of cooling or heating means. The large surface area of this external cavity enables efficient cooling or heating of the contents of the container, and providing that the container is of the size and external dimensions of a conventional beverage can enables the container to be filled and treated on existing filling lines. However, the container disclosed in WO96/29255 can be expensive to produce as it has to be made from at least three components which are then appropriately fixed together. This increases the unit cost of each container. It is an object of the present invention to provide a container body for a beverage or food container which can be manufactured most cost effectively. According to a first aspect of the present invention there is provided a container body for a beverage or food container, the container body having a tubular peripheral wall, a closed base at one end of the peripheral wall, and a top opening at the other end of the peripheral wall, wherein the base has a reentrant shape and defines an external cavity which extends within the peripheral wall, and wherein the container body has been formed by drawing a single sheet of metal. The container body of an embodiment of the invention has been formed to have a unitary construction by drawing a single sheet of metal to produce both the peripheral wall and the re-entrant shaped base. This means that after filling of the container it is necessary only to seam on a can end. As the finished can, therefore, is made of two components only, the manufacturing process is simplified and the cost of manufacturing is thereby reduced. In an embodiment, the ratio of the volume within the container body to the volume of said external cavity is in the range 4:1 to 1 :1. The ratio is chosen to provide a sufficient volume for contents within the container body, and yet enable efficient heating or cooling thereof by appropriate means within the external cavity as described in WO96/29255. Preferably, the external dimensions of at least the peripheral wall of the container body are the same as those of a conventional beverage or food can. For example, where the container body is substantially cylindrical and has a maximum diameter of 53mm, its height is substantially 88mm, 111mm or 134mm. Similarly, where the container body is substantially cylindrical and has a maximum diameter of 66mm, its height is substantially, 99mm, 115mm, 130mm, 150mm , or 168mm. The dimensions and shape of the container body are preferably arranged to enable the container body to be filled on conventional filling lines. In an embodiment, the metal from which the container body has been formed was coated or lacquered prior to the formation of the container body. Alternatively, the metal of the container body was coated or lacquered after the formation of the container body. For example, the metal is coated with a plastics material. The metal of the container body may be aluminium or steel. For example, the steel may be black plate steel, tin plate steel, tin free steel, or ECC steel. In an embodiment, the external cavity defined by the base is substantially cylindrical. In an alternative embodiment, the external cavity defined by the base has a surface which is fluted, corrugated or otherwise shaped to increase the surface area thereof. Preferably, the peripheral wall is necked and flanged adjacent the top opening thereof to accept a substantially conventional beverage or food can end. The invention also extends to a food or beverage can comprising a metal container body as defined above, the peripheral wall of the container body having been necked and flanged adjacent the top opening thereof, and a substantially conventional metal can end seamed on to the peripheral wall to close the top opening. According to a further aspect of the present invention there is provided a method of forming a container body for food or beverages, the method comprising the steps of drawing a single sheet of metal into a container body having a tubular peripheral wall, a closed base at one end of the peripheral wall, and a top opening at the other end of the peripheral wall, and forming the base into a re-entrant shape which defines an external cavity which extends within the peripheral wall. In an embodiment, the body is formed to be substantially cylindrical and to have external dimensions which are the same as those of a conventional beverage or food can. Preferably, the method further comprises the step of deep drawing the sheet of metal to form the container body. The method may additionally comprise the step of wall ironing at least part of the container body after its formation by deep drawing. Alternatively, the method may also comprise the step of wall ironing at least part of the metal of the container body before and/or during the deep drawing process. In one embodiment, the method further comprises the step of redrawing the metal. The method may also further comprise the step of rolling the metal of the container body outside in. Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal section of a preform used in forming an embodiment of a container of the present invention, Figure 2 shows an embodiment of a container body of the invention formed from the preform of Figure 1 , Figures 3 and 4 show longitudinal sections through successive preforms used to produce an alternative embodiment of a container body of the invention, Figure 5 shows a longitudinal section of a container body of an alternative embodiment of the invention formed from the successive preforms of Figures 3 and 4, Figure 6 shows a longitudinal section through a preform of a container body of a still further embodiment of the invention, Figure 7 shows a container body formed from the preform of Figure 6, Figure 8 shows a plan view of the base of the container body of Figure 7, Figure 9 shows a cross-section of an alternative, fluted, embodiment of a container body of the invention, Figures 10, 11 and 12 show longitudinal sections through container bodies of alternative embodiments of the invention, Figure 13 shows a plan view of the base of the container body of Figure 12, Figures 14 and 15 show longitudinal sections through still further embodiments of container bodies of the invention, Figures 16, 17 and 18 show longitudinal sections through successive preforms for forming a container body of a still further embodiment of the present invention, Figure 19 shows an embodiment of a container body formed from the successive preforms illustrated in Figures 16, 17 and 18, Figures 20 and 21 show longitudinal sections of further embodiments of a container body of the invention, and Figure 22 shows a longitudinal section of a conventional beverage can showing how the various dimensions thereof are measured. Figure 2 shows a longitudinal section of one embodiment of a container body 10 of the present invention. This container body is, as described in W096/29255, to be used to provide a can for beverages or food, which can may be self-cooling, self-heating, or provided with means to keep the contents warm or cold. The container body 10 has a substantially cylindrical peripheral wall 12 which has an opening, indicated at 14, at its top end. At its base end, the container body 12 has a base member 16 having a re-entrant shape such that it defines an elongate, external cavity 20 which extends within the peripheral wall 12 substantially along the longitudinal axis of the container body 10. It will be appreciated that the peripheral wall 12 and the base member 16 of the container body together define an internal cavity 22 in which the food or beverage is received. Whilst the external cavity 20 extends within the internal cavity 22, it is separated therefrom by the wall of the base member 16. Preferably, the ratio of the volume within the container body, that is the volume of the internal cavity 22, to the volume of the external cavity 20 is in the range 4:1 to 1 :1. Presently, a container body 10 as shown in Figure 2 will be formed in two, or more, parts. Thus, typically, a sheet of metal is formed and seamed to provide the cylindrical, peripheral, wall 12. A second sheet of metal is formed into the re-entrant shaped base member 16. Then, the two formed components are seamed together. However, the sealing compound used in the manufacture of conventional cans generally takes of the order of 24 hours to set, introducing a delay, and hence an expense, into the manufacturing process. Furthermore, the seams which are produced are always weak points in the can construction. For economy in the manufacturing process the present invention proposes that the container body should have a unitary construction. Such a unitary construction can reduce the number of operations in the manufacturing thereof and reduce the handling necessary of the container body. In addition, weak points such as a conventional seam are avoided. Figures 1 and 2 illustrate one method of forming a container body 10 to have a unitary construction. As indicated in Figure 1 , a sheet of metal is deep drawn to define a cylindrical preform having a cylindrical wall 12 joined by a stepped portion 24, to a further cylindrical section 26 which is closed by a concave base 28. The diameter of the cylindrical section 26 is less than the diameter of the cylindrical wall 12. The preform shown in Figure 1 may be made simply by deep drawing or by deep drawing together with wail ironing. In this respect, wall ironing may be used to reduce the wall thickness, whereby the amount of material in the final container body is reduced. Alternatively, the wall ironing may be used to provide the required shapes to the preform. The smaller diameter cylindrical section 26 of the preform of Figure 1 is then reverse drawn to define the re-entrant shaped base 16 of the container body 10 as shown in Figure 2. Once the container body 10 has the required shape, the peripheral wall 12 is necked as indicated at 30 and provided with a flange 32 around the top opening thereof. This configuration enables a substantially conventional can end (not shown) to be seamed onto the container body 10 after filling. In this respect, and as described further below, the container body 10 is formed to have the height and external diameter of a conventional beverage or food can. This means that the container body 10 can be filled and treated on conventional filling lines. It will be appreciated that before the can end is seamed onto the container body 10, the can has to be filled with the food or beverage. Furthermore, during the filling and end capping process, pasteurisation and other treatments on the can contents can be undertaken. Any treatments which involve heating or cooling the contents of the finished can are enhanced by the existence of the re-entrant shaped base which enhances the transfer of a heating or cooling effect to the can contents. The container body 10 of Figure 2 may be formed from a sheet of any appropriate metal. However, and as is conventional, it is preferred that the metal be either aluminium or steel. The metal may be coated or lacquered before or after the formation of the container body 10. For example, the metal may be pre- coated with a plastics material. Figure 5 shows a further embodiment of a container body 10 of the present invention. In this respect, in the drawings, similar features of the container body have been given the same reference numerals. It will be seen from Figure 5 that the embodiment of the container body 10 illustrated therein has the same features as described above with reference to Figure 2 although the shaping thereof is slightly different. However, the ratio of the volumes, for example, of the internal cavity 22 to the external cavity 20, remains within the range described. Figures 3 and 4 show steps in the formation of the container body 10 of Figure 5 from a sheet of steel or aluminium. In this embodiment, the sheet of metal is deep drawn to form the preform of Figure 3 which has first and second cylindrical sections 42 and 26 separated by a stepped portion 24. Thereafter, the larger diameter cylindrical section 42 is wall ironed to reduce its thickness and thereby produce the successive preform shown in Figure 4. The smaller diameter cylindrical section 26 of this second preform is then reverse drawn to produce the container body 10 of Figure 5. Figures 6 to 8 show the formation of a container body 10 having a base member 16 with a fluted surface. Thus, and as is shown in Figure 6, a cyiindrical body 44 is formed by deep drawing a sheet of metal and then wall ironing the cylindrical preform as required to produce a can with a substantial height and of substantially constant diameter. The base 46 of the preform so formed is drawn into a small re-entrant shape. The re-entrant base 46 is then turned partially outside in by a reverse or redrawing process or by a roll back process to define the base member 16 with its re-entrant shape. If the diameter of the external cavity 20 is kept the same as, or smaller than, the diameter of the cavity in the base 46 of the preform, the surface of the base member 16 becomes fluted as shown in the cross-section of Figure 8. This, of course, increases the surface area of the base member 16 and hence enhances the efficiency of the cooling or heating effect of the final can. The container body 10 of Figure 7 also has a petaloid base as indicated at 50. This petaloid base enables metal to be roiled around a moving radius to form the shapes illustrated. Whilst the fluted surface area of the external cavity 20 arises out of the manufacturing process of the can body 10 of Figure 7, it is possible to give the external cavity of a can body formed from any of these manufacturing techniques an increased surface area. For example, the surface of the external cavity 20 may be fluted, corrugated, or otherwise shaped as required. Figure 9 shows a plan view from below of an alternative embodiment of a container body 10 of the invention in which the external surface of the peripheral wall 12 has been given a fluted shape. However, so that this embodiment of the container body can be used on conventional filling lines, it is ensured that the maximum diameter of the peripheral wall 12 does not exceed that of the corresponding conventional can. Figures 10 to 15 show various embodiments of container bodies 10 of the present invention where the external cavity 20 has been shaped to meet further requirements. For example, in the embodiment of the container body 10 shown in Figure 10, the base 16 has been stepped at 52. The provision of such a step 52 gives strength to the base member 16 and thus enables the container body 10 to be formed from a thinner gauge material. In this embodiment also, a lower step 54 is also provided on the base member 16. This lower step 54 may be provided, for example, to act as a stop for components being fitted into the external cavity 20. In the embodiment shown in Figure 1 1. the base member 16 is beaded as shown at 56. This, again, is a strengthening measure enabling thinner gauge materials to be used in the manufacture of the container body 10. The beaded construction 56, of course, has the added advantage that it adds surface area as well as strength to the base member 16. The embodiment of the container body 10 shown in Figure 12 has an external cavity 20 with a reduced diameter, at least in its upper section 58. This reduction in the diameter of the external cavity 20 means that any heating or cooling effect in the smaller diameter section 58 of the cavity 20 has a reduced distance to travel in order to begin heating or cooling the contents of the container body. The reduced diameter section 58 of the external cavity 20 may remain cylindrical. Alternatively, and as shown in Figure 13, the section 58 of the external cavity 20 may be formed to have a substantially flattened or elliptical cross-section. The container body 10 shown in Figure 14 is formed to have an annular groove 60 extending around the external cavity 20. Such a groove 60 may be provided to receive or locate parts of a self-heating or self-cooling component (not shown) to be received within the external cavity 20. Similarly, the embodiment of the container body 10 shown in Figure 15 is formed to have an annular groove 62 extending around the exterior of the peripheral wall 12 adjacent to the base of the container body. Figure 19 shows a further embodiment of a container body 10 of the invention which has been made from a succession of preforms, three of which are shown in Figures 16, 17 and 18. The sheet of metal is drawn and redrawn to form the successive preforms of Figures 16, 17 and 18 and hence to form the container body 10. The base of the container body 10 is profiled as indicated at 64 to facilitate stacking of the filled and sealed cans. The container body 10 of Figure 20 has been provided with beading 66 on the exterior surface of the peripheral wall 12. As described earlier, beading can be used to increase the strength of the construction and to enable the use of metal which is either of a thinner gauge or is wall ironed to be thinner. The container body 10 shown in Figure 21 has had its outer peripheral wall 12 shaped for aesthetic reasons. Any of the embodiments of the container body illustrated may be embossed or otherwise patterned to enhance the appearance thereof. It will be appreciated from the above that the details of the manufacturing method for a container body of the invention can be chosen as required. Thus, the container body is given its unitary construction by drawing a single sheet of metal and, in general, the overall shape is given to the container body by drawing. However, ail or parts of the container body may be shaped or thinned by wall ironing. Embodiments including wall ironing have been described, but it is to be understood that any part of the container body may be appropriately wall ironed either alone or in conjunction with other parts thereof. For example, the re-entrant base, or parts thereof may be subject to wall ironing. Figure 22 shows a longitudinal section of a conventional can body for beer and carbonated drinks. In this respect, a can body 10 as shown in Figure 22 has a number of dimensions as marked. "A" is the open can height, "B" is the outside diameter, "C" is the neck diameter, "D" is the flange radius, "E" is the flange width, and "F" is the neck seaming clearance. The standard cans of the beverage industry have specified nominal contents which ranges from 150 millilitres to 500 millilitres. A table showing the maximum outside diameter "B", the neck diameter "C" and, the open can height "A" for each of the standard cans is given below: Nominal Content Diameter Height (ml) B/C (mm) A (mm) 150 53/50 88 200 53/50 111 250 53/50 134 275 66/57 99 330 66/57 115 330 66/52 115 375 66/57 130 440 66/57 150 500 66/57 168 500 66/52 168 The container bodies of the present invention are manufactured to have the maximum outside diameter "B" and the standard height "A" of a can having a specified content. However, because of the re-entrant shape of the base, although a container of the invention may initially appear to be exactly the same size as a standard can of nominal contents, it will be appreciated that the actual contents of a can body of an embodiment of the invention will be less than the contents of the corresponding standard can. However, the provision of can bodies 10 which meet the diameter and height standards ensures that container bodies of the invention can pass down standard filling and treatment lines. It will be appreciated that variations in and modifications to the embodiments of the invention as described and illustrated may be made within the scope of the appended claims.

Claims: CLAIMS 1. A container body for a beverage or food container, the container body having a tubular peripheral wall, a closed base at one end of the peripheral wall, and a top opening at the other end of the peripheral wall, wherein the base has a re-entrant shape and defines an external cavity which extends within the peripheral wall, and wherein the container body has been formed by drawing a single sheet of metal. 2. A container body as claimed in Claim 1 , wherein the ratio of the volume within the container body to the volume of said external cavity is in the range 4:1 to 1 :1. 3. A container body as claimed in Claim 1 or Claim 2, wherein the external dimensions of at least the peripheral wall of the container body are the same as those of a conventional beverage or food can. 4. A container body as claimed in Claim 3, wherein the container body is substantially cylindrical, has a maximum diameter of 53mm, and a height of o substantially 88mm, 111 mm or 134mm. 5. A container body as claimed in Claim 3, wherein the container body is substantially cylindrical, has a maximum diameter of 66mm, and a height of substantially 99mm, 115mm, 130mm, 150mm, or 168mm. 5 6. A container body as claimed in any preceding claim, wherein the dimensions and shape of the container body are arranged to enable the container body to be filled on conventional filling lines. o 7. A container body contained in any preceding claim, wherein the metal from which the container body has been formed was coated or lacquered prior to the formation of the container body. 8. A container body as claimed in any of Claims 1 to 6, wherein the metal of 5 the container body was coated or lacquered after the formation of the container body. 9. A container body as claimed in Claim 7 or Claim 8, wherein the metal is coated with a plastics material. 10. A container body as claimed in any preceding claim, wherein the metal of the container body is aluminium. 11. A container body as claimed in any of Claims 1 to 9, wherein the metal of the container body is steel. 12. A container body as claimed in Claim 11 , wherein the steel is black plate steel, tin plate steel, tin free steel, or ECC steel. 13. A container body as claimed in Claim 11 or Claim 12, wherein the steel is coil fed. 14. A container body as claimed in any preceding claim, wherein the container body has been formed by a deep drawing process. 15. A container body as claimed in Claim 14, wherein the forming process also included wall ironing at least part of the metal forming the container body. 16. A container body as claimed in Claim 14 or Claim 15, wherein the forming process additionally included redrawing the metal. 17. A container body as claimed in any of Claims 14 to 16, wherein the forming process also included the rolling of the metal outside in. 18. A container body as claimed in any preceding claim, wherein the external cavity defined by the base is substantially cylindrical. 19. A container body as claimed in any of Claims 1 to 17, wherein the external cavity defined by the base has a surface which is fluted, corrugated or otherwise shaped to increase the surface area thereof. 20. A container body as claimed in any preceding claim, wherein beading is formed on the surface of the external cavity defined by the base. 21. A container body as claimed in any preceding claim, wherein the peripheral wall is necked and flanged adjacent the top opening thereof to accept a substantially conventional beverage can end. 22. A container body as claimed in any of Claims 1 to 20 wherein the peripheral wall is necked and flanged adjacent the top opening thereof to accept a substantially conventional food can end. 23. A food or beverage can comprising a metal container body as claimed in any of Claims 1 to 22, the peripheral wall of the container body having been necked and flanged adjacent the top opening thereof, and a substantially conventional metal can end seamed onto the peripheral wall to close the top opening. 24. A method of forming a container body for food or beverages, the method comprising the steps of drawing a single sheet of metal into a container body having a tubular peripheral wall, a closed base at one end of the peripheral wall, and a top opening at the other end of the peripheral wall, and forming the base into a re-entrant shape which defines an external cavity which extends within the peripheral wall. 25. A method of forming a container body as claimed in Claim 24, wherein the body is formed to be substantially cylindrical and to have external dimensions which are the same as those of a conventional beverage or food can. 5 26. A method of forming a container body as claimed in Claim 25, wherein the container body is formed to have a maximum diameter of 53mm and a height of substantially 88mm, 111 mm, or 134mm. o 27. A method of forming a container body as claimed in Claim 25, wherein the container body has a maximum diameter of 66mm and a height of substantially 99mm, 115mm, 130mm, 150mm, or 168mm. 28. A method of forming a container body as claimed in any of Claims 24 to 5 27, further comprising the step of deep drawing the sheet of metal to form the container body. 29. A method of forming a container body as claimed in Claim 28, further comprising the step of wall ironing at least part of the container body after its formation by deep drawing. 30 .A method of forming a container body as claimed in Claim 28, further comprising the step of wall ironing at least part of the container body before and/or during the deep drawing process. 31. A method of forming a container body, further comprising the step of redrawing the metal. 32. A method of forming a container body as claimed in any of Claims 28 to 31 , further comprising the step of rolling the metal of the container body outside in. 33. A container body for food or beverages substantially as hereinbefore described with reference to the accompanying drawings. 34. A beverage or food can substantially as hereinbefore described with reference to the accompanying drawings. 35. A method of forming a container body for food or beverages substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: SEARLE MATTHEW JOHN, SEARLE, MATTHEW, JOHN
Applicants: SEARLE MATTHEW JOHN, THERMOTIC DEV LTD, SEARLE, MATTHEW, JOHN, THERMOTIC DEVELOPMENTS LTD.
Application year: 1999
Main classification: B65D1
IPC codes: B21D51, B65D1, B65D21, B65D81