AU702875B2

AU702875B2 - Tin can manufacturing process

Info

Publication number: AU702875B2
Application number: AU68847/94A
Authority: AU
Inventors: Antonio Henrique Kramer
Original assignee: Individual
Current assignee: Individual
Priority date: 1991-09-25
Filing date: 1994-08-01
Publication date: 1999-03-11
Anticipated expiration: 2011-09-25
Also published as: AU8480091A; AU6884794A

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION \For a Standard Patent

ORIGINAL

r TO BE COMPETED BY APPLICANT ANTON O HENRIQUE KRAMER ANTONI\ HENRIQUE KRAMER Name of Applicant Actual Inventor(s Address for Service: WRAY ASSOCIATES, Primary Industry House, 239 Adelaide Terrace, Perth, Western Australia, 6000.

Attorney code: WR Invention Title: "TIN CAN MANUFACTURING PROCESS" The following statement is a full description of this invention, including the best method of performing it known to us:- 1 -2- TITLE: "Tin Can Manufacturing Process" This invention relates to the manufacture of cans, i.e. containers made of sheet metal, in particular tin cans.

The invention provides a can comprising a sheet steel cover fixed to a sheet steel body by a double seam, the double seam comprising a cover hook overlapped by a body hook, the cover being countersunk and having a peripheral portion which rises up the inside of the can body, extends outwards over the bend of the body hook, descends over the outside of the body hook, and is bent upwards to constitute the cover hook between the body hook and the body, the sheet steel having a thickness s of up to 0.24 mm and a hardness of at least 57 HR 30 T, characterised in that the seam has a height h, a body hook height b, a cover hook height c, and a countersink k which are such that h mm, b=c= 1.0 mm, and k 1.6 mm.

'Such a seam is significantly smaller than conventional seams and can conveniently be referred to as a "micro-seam". 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 e 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 20 the volumetric capacity of the can.

Substantial savings of sheet metal may result, both in quantity as well as cost, by employing a thinner double-reduced sheet metal, in particular of 0.16 mm thickness and DR8 temper (hardness 73 3 HR 30T), the price of which is 21.2 to 28.3% lower than that of the conventionally used single-reduced sheet metal, i.e. of 0.22 to 0.24 mm thickness and T4 (hardness 61 4HR 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 IV T u-'i LU L~ L -3products and the so-called sanitary cans, are nonnally obtained by using singlereduced tin-plated sheet metal (steel) of 0.22 to 0.24 mm thickness with T4 temper for the top anl the bottom, features which also allow the employment of this sheet metal for r'Ticro-seaming, however, witl out the advantages of the larger savings obtained as a result of the use of a sheet metal of 0.16 mm thickness and DR8 temper.

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

The invention also resides in a can making process for forming a seam between a can end and a body of a can by micro-seaming which comprises the following steps: assembling a flange body of a can with at least one curled can end, said can body and said curled can end each having profile and curling 15 dimensions necessary for connecting one to the other, said can end being made of double reduced sheet material; and said can body being made of any commercially available material; and e micro-seaming said can end to body of said can to provide a seam between the can end and the body of said can wherein the size of the :i 20 seam is reduced as compared to conventional can end seams without changing the volumetric capacity of the can.

In another form the invention resides in a tin can making process for forming a seam between a can end and a body of a can by micro-seaming which comprises the following steps: assembling a flanged body of a can with at least one curled can end, said can body and said curled can end each having profile and curling R4AL, dimensions necessary for connecting one to the other, said can end being made of double-reduced sheet material of 0.16 mm thickness or less; and said can body being made of any commercially available material; and micro-seaming said can end to said can body to provide a seam between the can end and the can body wherein the size of the seam is reduced as compared to conventional can end seams without changing the volumetric capacity of the can.

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 can body, with their respective dimensions, of a conventional can end 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 double seam obtained by the conventional process, employing a sheet metal of 0.22 mm thickness and T4 *o 15 temper, with relatively large fixing dimensions (detail I in Figure 3); Figure 2 is a sectional view, showing the micro-seam obtained in the new can, employing a sheet metal of lesser thickness, i.e. 0.16 mm, and greater hardness, i.e. with DR8 temper, in which the fixing dimensions are perceptibly reduced in comparison with the conventional seam (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 4 is a side view of a ready or finished new can, the height of its body being appreciably lower, without changing its volumetric capacity; Figure 5 is a top view of the disc destined for the end of the conventional can, cut with the normally used diameter employed in the conventional fixing processes; I- Figure 6 is a top view of a disc destined for the end of the new can, cut with a perceptibly smaller diameter; Figure 7 is a top view of an already stamped end for the conventional can; Figure 8 is a top view of an already stamped end of the new can; Figure 9 is a sectional view, with an enlarged detail, of an already stamped end for the conventional can; Figure 10 is a sectional view, with an enlarged detail, of an already stamped end 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 °o o" 15 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 (covers) 1 of sheet metal having a thickness of 0.22 mm (or up to 0.24 mm) and a T4 temper (61 4 HR 30T), 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 double seamrn 3 comprising interlocking folds at the edge portions of the end wall 1 and the peripheral wall 2.

-6- 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 end walls 11 of sheet metal having a thickness of 0.16 mm and a DR8 temper (73 3 HR 30T), 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). As can be seen in Figure 2, the new can is manufactured by a process which includes forming a double seam (micro-seam) 13 (of smaller size than the double seam 3) comprising interlocking folds at the edge portions of the end wall 11 and the peripheral wall 12. Figure 2 shows the seam height of 1.5 mm, the body hook height of 1.0 mm, and the countersink of 1.6 mm, as well as the seam thickness of 0.88 mm approximately 5 times the sheet thickness of 0.16 mm, since the seam comprises five layers).

The new manufacturing process may provide tin cans, destined for the most diverse purposes of use, with micro-seaming of tops and bottoms with substantial material savings, without affecting the volumetric 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 ends 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, in addition to a reduction of the height of the cylindrical body of the can, as shown in Figures 3 and 4 and in Figures 11 to 14, reductions which are obtained without reducing the volumetric 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 the substantial materials savings allowed by the use of a double reduced sheet metal, i.e. of DR8 temper and 0.16 mm thickness, for the manufacturing of the ends of cans, the use of this lower price sheet metal is not possible for the conventional type of seaming, since because of the high hardness of the material and its thinness, the folds of the a a -7hook sections would present enormous deformations which would be transmitted into a general seaming 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 closure, which represent the fundamental requirements of good seaming and quality of these containers.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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Claims

1. A can comprising a sheet steel cover fixed to a sheet steel body by a double seam, the double seam comprising a cover hook overlapped by a body hook, the cover being countersunk and having a peripheral portion which rises up the inside of the can body, extends outwards over the Lend of the body hook, descends over the outside of the body hook, and is bent upwards to constitute the cover hook between the body hook and the body, the sheet steel having a thickness s of up to 0.24 mm and a hardness of at least 57 HR T, characterised in that the seam has a height h, a body hooK height b, a cover hook height c, and a countersink k which are such that h 1.5 mm, b=c= 1.0 mm, and k 1.6 mm.

2. A can as claimed in claim 1, in which s 0.16 mm.

3. A can as claimed in claim 2, in which the sheet steel has a hardness of 73 3 HR

4. A can as claimed in claim 2 or 3, in which the seam has a thickness of 0.88 mm.

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

6. A tin can making process for forming a seam between a can end and a body 20 of a can by micro-seaming which comprises the following steps: assembling a flanged body of a can with at least one curled can end said can body and said curled can end each having a profile and curling dimensions necessary for connecting one to the other, said can end being made of double-reduced sheet material of 0.16 mm thickness or LL T, C less; and said can body being made of any commercially available material; and micro-seaming said can end to said can body to provide a seam between the can end and the can body wherein the size of the seam is reduced as compared to conventional can end seams without changing the volumetric capacity of the can.

7. A can making method substantially as herein described with reference to Figures 2, 4, 6, 8, 10, 12, and 14 of the accompanying drawings. Dated this THIRD \ay of DECEMBER 1998. ANTONIO HENRIQU, KRAMER Applicant Wray Associates Perth, Western Australia Patent Attorneys for the Applicant 0 OS *P 5 -7 0 I I II ABSTRACT A can comprising a sheet steel cover fixed to a sheet steel body by a double seam, the double seam comprising a cover hook overlapped by a body hook, the cover being countersunk and having a peripheral portion which rises up the inside of the can body, extends outwards over the bend of the body hook, descends over the outside of the body hook, and is bent upwards to constitute the cover hook between the body hook and the body, the sheet steel having a thickness s of up to 0.24 mm and a hardness of at least 57 HR 30 T, characterised in that the seam has a height h, a body hook height b, a cover hook height c, and a countersink k which are such that h 1.5 mm, b=c= 1.0 mm, and k 1.6 mm. a a RA A/ o I I II Is s