GB2246551A

GB2246551A - Can manufacture

Info

Publication number: GB2246551A
Application number: GB9115195A
Authority: GB
Inventors: Antonio Henrique Kramer
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-07-13
Filing date: 1991-07-12
Publication date: 1992-02-05
Anticipated expiration: 2011-07-12
Also published as: DE4123170A1; NL9101220A; BR9003371A; ITMI911939A0; PE32491A1; GB2246551B; CH685192A5; ITMI911939A1; FR2664512A1; FR2664512B1; IT1251786B; DE4123170C2; JPH04231126A; GB9115195D0

Description

CAN MANUFACTURE This invention relates to the manufacture of cans, i.e.

containers made of sheet metal, in particular tin cans.

The invention provides a can in which at least one end wall is made from sheet metal which is thinner and harder than the sheet metal currently used in making end walls of cans.

In one aspect the invention provides a can comprising at least one sheet metal end wall fixed to a sheet metal peripheral wall by a structure comprising interlocking folds at the edge portions of the end wall and the peripheral wall, the sheet metal of the end wall having a thickness of less than 0.22 mm and a hardness greater than that produced by T4 heat treatment.

In another aspect the invention provides a can comprising at least one sheet metal end wall fixed to a sheet metal peripheral wall by a structure comprising interlocking folds at the edge portions of the end wall and the peripheral wall, the sheet metal of the end wall being C.16 mm thick and having been subjected to DR8 heat treatment.

The invention also provides a can manufacturing process, by which the tin cans will be formed by micro-fixing, wherein for the manufacture of the can is employed a relatively thinner and harder sheet metal, with 0.16 mm thickness and DR8 heat treatment for the top and the bottom, providing a sensible reduction of the hooks and other dimensions of the fixing folds, both for the top as well as for the bottom of the can, as well as for the hooks and extremities of the can body, without changing its holding capacity.

The invention enables one to reduce the dimensions of the fixing folds at the top and/or the bottom of a cylindrical can, for example, reducing the diameters of the cut-outs employed for the manufacture of the top and/or the bottom of the can, as well as, consequently, significantly reducing the height of the can, this without change of the capacity of the can. Substantial savings of sheet metal may result, both in quantity as well as cost, by employing a thinner and harder sheet metal, in particular of 0.16 mm thickness and DR8 heat treatment, the price of which is 21.2 to 28.3% lower than that of the conventionally used sheet metal, i.e. of 0.22 to 0.24 mm thickness and T14 heat treatment.

As is known to those skilled in the art, the currently used conventional cans destined to serve as packaging for the most divers products, particularly for food products and the so-called sanitary cans, are normally obtained by using tin-plated sheet metal (steel) of 0.22 to 0.24 mm thickness with T4 heat treatment for the top and the bottom, features which would also allow the employment of this sheet metal for micro-folding, however, without the advantages of the large savings obtained as a result' of the use of a sheet metal of 0.16 mm thickness and DR8 heat treatment.

The invention is applicable to tin cans with an electrically welded or deep drawn body, i.e., those bodies with no overlap or two thicknesses where the joint is obtained by folds soldered with tin or lead or thermoplastics.

The invention will be described further, by way of example, with reference to the accompanying diagrammatic drawings which show, for comparison purposes, both the cut-out discs of the top and bottom, as well as the fixed parts and the can body, with their respective dimensions, of a conventional can and of a new can according to the invention. In the drawings, the dimensions indicated are in millimetres.

Figure 1 is a sectional view, showing the fixing structure obtained by the conventional process, i.e. by employing a sheet metal of 0.22 mm thickness and T4 heat treatment, with relatively large fixing dimensions (detail I in Figure 3); Figure 2 is a sectional view, showing the fixing structure obtained in the new can, i.e. by employing a sheet metal of lesser thickness, i.e. 0.16 mm, and greater hardness, i.e. with DR8 heat treatment, of which the fixing dimensions are perceptibly reduced in comparison with the conventional can (detail II in Figure 4); Figure 3 is a side view of a ready or finished conventional can, the height of its body being appreciably greater than that of the new can; Figure 14 is a side view of a ready or finished new can, the height of its body being appreciably lower, without changing its holding capacity;; Figure 5 is a top view of the disc destined for the top or bottom of the conventional can, cut with the normally used diameter employed in the conventional fixing processes; Figure 6 is a top view of a disc destined for the top or bottom of the new can, cut with a perceptibly smaller diameter; Figure 7 is a top view of an already stamped top or bottom for the conventional can; Figure 8 is a top view of an already stamped top or bottom of the new can; Figure 9 is a sectional view, with an enlarged detail, of an already stamped top or bottom for the conventional can; Figure 10 is a sectional view, with an enlarged detail, of an already stamped top or bottom of the new can, showing the appreciable measurement reductions of the fixing hook section; Figure 11 is a side view of a cylindrical body destined for the conventional can;; Figure 12 is a side view of a cylindrical body, with an appreciably reduced height, destined for the new can; Figure 13 is a side view of a can body, already provided with fixing flanges, for the conventional can; and Figure 14 is a side view of a can body, with its already made flanges, showing perceptibly reduced dimensions, for the new can.

It will be seen that Figures 1, 3, 5, 7, 9, 11, and 13 illustrate a conventional can and the parts from which it is made. In particular it has top and bottom end walls 1 of sheet metal having a thickness of 0.22 mm (or up to 0.24 mm) and a hardness produced by T4 heat treatment, and a body with a peripheral wall 2 of sheet metal having a thickness of 0.16 mm.

As can be seen in Figure 1, the conventional can is manufactured by a process which includes forming a structure 3 comprising interlocking folds at the edge portions of the end wall 1 and the peripheral wall 2.

Similarly, Figures 2, 4, 6, 8, 10, 12, and 14 illustrate a new can according to the invention, and the parts from which it is made. It has top and bottom end walls 11 of sheet metal having a thickness of 0.16 mm and a hardness produced by DR8 heat treatment, and a body with a peripheral wall 12 of sheet metal having a thickness of 0.16 mm (preferably identical to the sheet metal of the end walls 11). Again, as can be seen in Figure 2, the new can is manufactured by a process which includes forming a structure 13 (of smaller size than the structure 3) comprising interlocking folds at the edge portions of the end wall 11 and the peripheral wall 12.

The new manufacturing process may provide tin cans, destined for the most diverse purposes of use, with a micro-fixing of tops and bottoms with substantial material savings, owing to the use of a thinner sheet metal, i.e. 0.16 mm thick, which is relatively harder, i.e. with DR8 heat treatment, replacing the conventionally used sheet metal for the known fixing processes, where normally is employed a sheet metal 0.22 to 0.24 mm thick and relatively softer, i.e. with T4 heat treatment, and this without affecting the holding capacity of the cans thus obtained.

This process allows advantageous material savings, provided by the reduction of the diameters of the discs which form the top and the bottom of the can, as shown in Figures 5 and 6, as well as a reduction of the hook-section dimensions and other fixing folds, as shown in Figures 1 and 2 and in Figures 9 and 10, in addition to a reduction of the height of the cylindrical body of the can, as shown in Figures 3 and 14 and in Figures 11 to 14, reductions which are obtained without reducing the capacity of the can.

For a perfect evaluation of the actual advantages resulting from the new process it is worthwhile to note that, in addition to this substantial materials savings, allowed by the use of a double reduced sheet metal, i.e. of DR8 heat treatment and 0.16 mm thickness, for the manufacturing of the tops and bottoms of the cans, the use of this lower price sheet metal is not possible for the conventional type of fixing, since because of the high hardness of the material and its thinness, the folds of the hook sections would present enormous deformations which would be transmitted into a general fixing deformation which, in addition to an extremely bad appearance of the can, would lead to its technical condemnation for not providing a perfect seal and, consequently, an ideal hermetic enclosure, which represent the fundamental requirements of a good fixing and quality of these containers.

Claims

Claims:

1. A can comprising at least one sheet metal end wall fixed to a sheet metal peripheral wall by a structure comprising interlocking folds at the edge portions of the end wall and the peripheral wall, the sheet metal of the end wall having a thickness of less than 0.22 mm and a hardness greater than that produced by T14 heat treatment.

2. A can as claimed in claim 1, in which the sheet metal of the end wall is 0.16 mm thick.

3. A can as claimed in claim 1 or 2, in which the sheet metal of the end wall has a hardness produced by DR8 heat treatment.

4. A can comprising at least one sheet metal end wall fixed to a sheet metal peripheral wall by a structure comprising interlocking folds at the edge portions of the end wall and the peripheral wall, the sheet metal of the end wall being 0.16 mm thick and having been subjected to DR8 heat treatment.

5. A can as claimed in any preceding claim, in which the sheet metal of the peripheral wall is equal in thickness to the sheet metal of the end wall.

6. A can as claimed in any preceding claim, in which the sheet metal of the peripheral wall is equal in hardness to the sheet metal of the end wall.

7. A can manufacturing process in which at least one sheet metal end wall is fixed to a sheet metal peripheral wall by interlocking folds at the edge portions of the end wall and the peripheral wall, the end wall being made from sheet metal having a thickness of less than 0.22 mm and a hardness greater than that produced by T14 heat treatment.

8. A can manufacturing process in which at least one sheet metal end wall is fixed to a sheet metal peripheral wall by interlocking folds at the edge portions of the end wall and the peripheral wall, the end wall being made from sheet metal which is 0.16 mm thick and has been subjected to DR8 heat treatment.

9. A can substantially as described with reference to, and as shown in, Figures 2, 14, 6, 8, 10, 12, and 14 of the accompanying drawings.

10. A can manufacturing process substantially as described with reference to Figures 2, 4, 6, 8, 10, 12, and 14 of the accompanying drawings.