Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
  • B65D1/00—Containers having bodies formed in one piece, e.g. by casting metallic material, by moulding plastics, by blowing vitreous material, by throwing ceramic material, by moulding pulped fibrous material, by deep-drawing operations performed on sheet material
  • B65D1/40—Details of walls
  • B65D1/42—Reinforcing or strengthening parts or members
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
  • B21D22/20—Deep-drawing
  • B21D22/28—Deep-drawing of cylindrical articles using consecutive dies

Definitions

• This invention relates to wall-ironed cans. It is now common practice to make a can from a disc of sheet metal. The disc is formed into a shallow container, the wall of which is then ironed to extend the wall whilst reducing 5 its thickness. This operation is described, for example, in European Patent Specification No. 17434. Forming and ironing operations are usually carried out in a single operation by a punch acting within forming and ironing dies. It is also common practice to shape the punch, so that slight thickening 10of the rim end part of the wall is produced. This thickened rim part is flanged and a lid * is sealed to it. The resultant can has relatively thickened base and rim parts with a thin cylindrical wall between.
• Such circumferential ribs when provided, are usually formed in a separate operation for the purpose of resisting radial collapse of the can, due to either increased oor decreased pressure in the can caused by the contents or by treatment, such as cooking of the contents.
• These circumferential ribs may induce axial collapse rather than resist it and, for this reason, it has also been proposed to provide discontinuous circumferential ribs, so that portions of the can wall between the ribs are not formed. Even with this
• the present invention provides a wall-ironed can having • base and rim portions and an intermediate wall therebetween which is provided with thickened portions defining- axial ribs extending towards the rim portion from adjacent the base portion. Preferably at least three such ribs are provided substantially equally spaced around the can.
• the base and rim portions are thicker than 0the portions of the intermediate wall between the ribs.
• the invention also resides in a method of manufacturing a can utilising a wall-ironing operation in which a punch is moved through an ironing die to form the can wall, wherein the punch has axial recessed parts in its circumferential surface, 5so that thickened portions are defined in the can wall extending axially from adjacent the base of the can.
• the invention also resides in apparatus for manufacturing a can by wall—ironing, comprising an ironing die and a punch movable through the die, wherein the punch has axial recessed parts for forming thickened portions in the ironed wall of the can, extending axially from adjacent the base portion of the can.
• the punch may have a relatively smaller diameter portion for forming a thickened rim portion of the can.
• the axial thickened portions, or ribs considerably strengthen the can to reduce the risk of buckling under co pressive forces and, surprisingly, no more material is required to produce the ribs.
• the rim end of the ironed wall is always uneven and slightly overlong and has to be trimmed. It has been found that the extra material for the ribs is obtained from the part to be trimmed.
• Figure 1 is a sectional diagrammatic view of wall-ironing apparatus for making a can
• Figure 2 is a diagrammatic perspective view of a punch of the apparatus, modified according to the invention and showing thereon, in section, a can
• Figure 3 is a detail diagrammatic sectional view on the line 3—3 of Figure 2;
• FIG 4 is a detail diagrammatic sectional view on the line 4—4 of Figure 2.
• a shallow walled blank 15 is forced by a punch 50 through a forming die 21 held in a ring 26 to reduce the area of the base of the blank and increase the length of the wall.
• the blank is separately formed from a disc by an earlier conventional operation.
• the punch then forces 10 the reformed blank through ironing dies 22, 23 held in rings 30, 33 and stamps the bottom of * the blank on a die 24 formed with circular ridges 35.
• the ironing dies effect a wall-ironing operation to lengthen the wall whilst reducing its thickness.
• the free end of the ironed wall is then trimmed.
• the operation may be as described in European Patent Specification No. 17434 which is incorporated herein by reference.
• the punch is formed with slightly tapering portions 50, 51 with a cylindrical main portion 52 20 therebetween.
• the tapering portions define thickened rim 55 and base 56 portions respectively on a can 54, formed and ironed on the punch, relative to the thickness of the main wall 53 of the can between those portions.
• the thicknesses illustrated are, of necessity, greatly exaggerated.
• the main 25 portion 52 of the punch has axial recessed parts 60 equally spaced circumferentially and extending between the portions 50, 51. These recessed parts are defined by flats in this particular example, but may be defined by concave surfaces.
• the formation of a flat 60 is illustrated in Figure 3 where the 30 dotted line 61 shows an imaginary continuation of the main cylindrical outer surface of the punch.
• the flat may be 2 to 4
• the can wall is provided with internal ribs 62 extending axially from the rim portion 55 to the base portion 56. These ribs ( Figure 4) are
• OMPI defined by thickened portions of the can wall, the thickening being complementary in shape to the flats which formed them.
• ribs 62 may be provided.
• the result is a can having reinforced rim and base portions with the rim supported by the ribs 62, which reduce the risk of buckling of the can under compressive forces.
• the intermediate wall 52 may then be subjected to a separate forming operation to form circumferential ribs, or beads, in the axially central region of the wall, for resisting radial collapse of the wall either inwardly or outwardly.
• This operation is not essential for all purposes and is commonplace in the art and has, therefore, not been described or illustrated in this specification. It is not necessary for the axial ribs to extend the full length from the base portion to the rim portion. They may, for example, extend from the base portion to adjacent the first of the circumferential ribs, where these are provided. It is also possible to provide axial ribs of different lengths and/or widths.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Ceramic Engineering (AREA)
• Shaping Metal By Deep-Drawing, Or The Like (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1982
  • 1982-11-26 EP EP19830900054 patent/EP0096683A1/de not_active Withdrawn
  • 1982-11-26 WO PCT/GB1982/000336 patent/WO1983001916A1/en unknown

Non-Patent Citations (1)

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