EP3495059A1 - Verfahren zur herstellung von dosenkörpern - Google Patents

Verfahren zur herstellung von dosenkörpern Download PDF

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Publication number
EP3495059A1
EP3495059A1 EP17205574.1A EP17205574A EP3495059A1 EP 3495059 A1 EP3495059 A1 EP 3495059A1 EP 17205574 A EP17205574 A EP 17205574A EP 3495059 A1 EP3495059 A1 EP 3495059A1
Authority
EP
European Patent Office
Prior art keywords
redraw
cup
wall
radius
ironing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP17205574.1A
Other languages
English (en)
French (fr)
Inventor
Alexander JIMMINK
Henri Kwakkel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tata Steel Ijmuiden BV
Original Assignee
Tata Steel Ijmuiden BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tata Steel Ijmuiden BV filed Critical Tata Steel Ijmuiden BV
Priority to EP17205574.1A priority Critical patent/EP3495059A1/de
Publication of EP3495059A1 publication Critical patent/EP3495059A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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
    • 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
    • B21D22/201—Work-pieces; preparation of the work-pieces, e.g. lubricating, coating
    • 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
    • B21D22/30—Deep-drawing to finish articles formed by deep-drawing
    • 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
    • B21D51/00—Making hollow objects
    • B21D51/16—Making hollow objects characterised by the use of the objects
    • B21D51/26—Making hollow objects characterised by the use of the objects cans or tins; Closing same in a permanent manner

Definitions

  • This invention relates to an improved method of producing can bodies from a polymer coated metal substrate by the drawing and wall-ironing (DWI) process.
  • DWI drawing and wall-ironing
  • the principle of draw- and wall ironing technology is well-known.
  • the technology requires a circular blank for forming the (usually) cylindrical can body.
  • the metal for the can bodies is usually supplied in coiled form.
  • the coiled metal is uncoiled and blanks are stamped from the metal and produced into a so-called initial cup by a deep-drawing operation. This cup is deep drawn until no flanges are present.
  • the cup is then redrawn in one or more redrawing steps to the final can diameter.
  • the maximum reduction of diameter is determined by the limiting drawing ratio, which is defined as the ratio of the maximum blank diameter that can be safely drawn into a cup without flange to the punch diameter.
  • the diameter of the initial cup is significantly larger than the diameter of the redrawn cup.
  • the thickness of the redrawn cup wall is reduced by wall-ironing the cup and produce a can body for a 2-piece can. This process involves pushing the redrawn cup through one or more ironing rings by means of a punch. The gap between the punch and the ironing ring determines the final thickness of the wall of the can body. For instance, a wall thickness of 0.30 mm in the redrawn cup may be reduced to 0.10 to 0.14 mm. Of course the height of the wall increases as a result.
  • the edge of the can body has to be trimmed, because as a result of the inherent anisotropy of the metal the height of the can body is not the same everywhere on the circumference of the edge of the can body.
  • This trimming also allows the final height of the can body to be tailored and prepared for the necking and flanging operation that is needed to receive the lid (the second piece of the two-piece can) after filling the can.
  • this lid is usually an easy open end, but it may also be a conventional lid which is to be opened by a can opener.
  • This type of can used to be made from tinplate This type of can used to be made from tinplate.
  • copious amounts of lubricants are needed, not only to 'cool away' the heat generated by the work-hardening of the material, but also to prevent tool surface wear and surface damage, and to provide a good can surface. Any swarf needs to be removed very thoroughly from the can body and therefore a very thorough washing is required.
  • the copious amounts of lubricant and the need for a washing stage leads to the identification of the DWI-process as a 'wet DWI' process.
  • This metal sheet which may be aluminium sheet or steel sheet, can be produced as coiled metal and be provided with a polymer coating on one or both sides by film lamination or direct extrusion or the like.
  • This polymer coated metal sheet is suitable for producing can bodies by DWI and it is even possible to perform this with a minimum or even no lubricant.
  • the polymer coating layer acts as lubricant. Also, because there is no exposed metal surface, there is also no risk of producing swarf, and therefore the need to wash the can bodies after the DWI-process is removed. Consequently this DWI process is referred to as a 'dry DWI' process.
  • FIG 1 A schematic drawing of the set-up for redrawing an initial cup is provided in figure 1 .
  • the operative part of the redraw die as well as the operative part of the redraw sleeve are highlighted in figure 1 with the magnifying glass. These parts are depicted in more detail in figure 2a and 2b .
  • the operative part is the part described by the radius R and delimited by the dashed lines.
  • the angle over which the radius R angle is provided is 90°, i.e. the operative part is a quarter circle as seen in cross-section in figure 2a and 2b .
  • the redraw die 2 as depicted in cross section in figure 1 is provided with a circular hole through which the initial cup 4 is pushed by a cylindrical punch 1 while being held to the flat area of the redraw die by the annular redraw sleeve 3.
  • Figure 1 is schematic also in the sense that there is room between the cup, sleeve and redraw die, while in practice the redraw sleeve will push the initial cup onto the redraw die to prevent wrinkling
  • the method of the invention with a decreased radius of the operative part of the redraw die R rd or the radius of the operative part of the redraw sleeve R rs allows to stretch-draw the polymer coated metal substrate.
  • the reduction of the radius or radii is essential if the can body is required to have a certain height. Without the reduction of the radius or radii the polymer coated metal sheet would slip as a result of the reduced friction as compared with the same sheet with a metallic surface.
  • a degree of tension must be built up in the metal sheet, and the building up of this tension is possible as a result of the reduced radius or radii.
  • the method according to the invention has the advantage that in comparison to conventional practice, the elongation of the can wall by redrawing of the polymer coated redrawn cup takes place to a larger extent in the cupping stage and redrawing stage and to a lesser extent in the ironing stage.
  • the reduced radius or radii of OP and/or OPRS has to be combined with a higher force imposed though the redraw sleeve upon the flange of the initial cup during the redraw step (this force is referred to as blank holder force or BHF, because the initial cup can be considered as a blank for the redrawing step).
  • This force is referred to as blank holder force or BHF, because the initial cup can be considered as a blank for the redrawing step).
  • the redraw sleeve is cylindrical to achieve tension in the material as soon as possible during the redrawing. In conventional redraw processes the redraw sleeve is not cylindrical but tapered (see figure 3a ).
  • the process according to the invention is performed with only one wall-ironing ring in the wall-ironing step.
  • This process benefits from a maximum shift of deformation to the cupping and redrawing stage.
  • the stretching of the wall of the initial cup during the redrawing step(s) is maximised, so that the only one wall-ironing ring is sufficient to finish the can body with the desired wall height.
  • the wall of the redrawn cup is not stretched to the same extent, or not at all, so that more reduction needs to be generated by the wall-ironing step, and this step then requires at least two rings.
  • the radius R rd or R rs is expressed in terms of the initial thickness of the polymer coated metal sheet, which is also the thickness of the circular blank used to produce the initial cup from.
  • the radius is at most 3 times the thickness of the polymer coated metal sheet or blank, preferably one radius or both radii is at most 2.75 times the thickness of the polymer coated metal sheet or blank, and more preferably at most 2.5 times. Even more preferably the radius or both radii is at most 2.25 or 2.0 times the thickness of the polymer coated metal sheet or blank.
  • both R rd and R rs have the same value.
  • a burnishing step is provided by pushing the can body after the ironing operation through a burnishing ring. This relieves the tension in the can body wall and allows the can body to be stripped off easily.
  • the blank holder force is reduced just before the edge of the initial cup enters the OP of the redraw die by reducing the BHF partly or completely, e.g. by lifting the redraw sleeve.
  • this lifting of the redraw sleeve is performed while the edge of the initial cup is less than 5 mm away from the OP. This ensures that the edge of the polymer coated metal is not pinched and this prevents the formation of hairs. It is clear that this process is more controlled the lower the anisotropy of the metal.
  • the so-called ears may be too large to enable the timely lifting of the redraw sleeve because the edge of one part may have already entered the OP while the ears are still more than 5 mm removed from the OP.
  • the polymer coated steel substrates that can be processed by the process according to the invention are preferably based on polycondensates, such as polyesters, copolyesters (including PET, PBT, polyethylene furanoate (PEF), poly(lactic acid) (PLA)) or polyamides, polyolefins, elastomers, crystallisable polyaddition polymers, or any other polymer that can be formed in a film by extrusion.
  • the polymer coating may consist of one or more layers.
  • the polymer coating layer comprises or consists of polyethylene terephthalate, IPA-modified polyethylene terephthalate, CHDM-modified polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene furanoate, poly (lactic acid) or copolymers or blends thereof.
  • the sheet metal preferably is tin coated steel sheet (tinplate), chromium-chromiumoxide coated steel sheet (ECCS), tinplate which was diffusion annealed to form an iron-tin alloy consisting of at least 80% of FeSn (50 at.% iron and 50 at.% tin) thereupon, or a chromium-chromiumoxide coated steel sheet produced by electroplating from a trivalent chromium electrolyte
  • a 65 mm diameter can body is produced from 0.25 mm steel sheet with a polyester coating of 25 ⁇ m on both sides, leading to a total thickness t of 0.30 mm.
  • the steel is a common extra low carbon (ELC) steel (see table #). Blanks were produced therefrom and these were processed into initial cups. Using a redraw die with R rd of 1.0 mm and of R rd of 0.425 mm redraw cups were made in a single redraw step.
  • Table # Composition of ELC-steel (in wt.%, bal. Fe and residual elements) C Mn N Alsol P S B 23 146 1.9 18 12 8 1.7
  • the redrawn cup wall thickness is presented in figure 4 .
  • the height increases towards the top because of the material flow during deep drawing and the compressive forces in the material in the circumference. This increased thickness is subsequently ironed 'out' in the subsequent ironing step. From figure 4 it can be seen that the height of the cup wall increases from 69 mm at R rd 1 mm to 80 mm at R rd of 0.425 mm, which is a 17% increase. This increase in wall height is the result of the stretch-draw operation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Shaping Metal By Deep-Drawing, Or The Like (AREA)
EP17205574.1A 2017-12-05 2017-12-05 Verfahren zur herstellung von dosenkörpern Withdrawn EP3495059A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP17205574.1A EP3495059A1 (de) 2017-12-05 2017-12-05 Verfahren zur herstellung von dosenkörpern

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP17205574.1A EP3495059A1 (de) 2017-12-05 2017-12-05 Verfahren zur herstellung von dosenkörpern

Publications (1)

Publication Number Publication Date
EP3495059A1 true EP3495059A1 (de) 2019-06-12

Family

ID=60582494

Family Applications (1)

Application Number Title Priority Date Filing Date
EP17205574.1A Withdrawn EP3495059A1 (de) 2017-12-05 2017-12-05 Verfahren zur herstellung von dosenkörpern

Country Status (1)

Country Link
EP (1) EP3495059A1 (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2241184A (en) * 1989-11-13 1991-08-28 Toyo Seikan Kaisha Ltd Method of redrawing a metal cap
US5144824A (en) * 1989-10-18 1992-09-08 Toyo Seikan Kaisha, Ltd. Process for the preparation of a thickness-reduced draw-formed can
EP0664169A1 (de) * 1993-12-22 1995-07-26 TOYO KOHAN Co., Ltd Nachziehverfahren
EP0667193A1 (de) * 1994-02-15 1995-08-16 Toyo Seikan Kaisha Limited Verfahren zur Herstellung falznahtloser Dosen

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5144824A (en) * 1989-10-18 1992-09-08 Toyo Seikan Kaisha, Ltd. Process for the preparation of a thickness-reduced draw-formed can
GB2241184A (en) * 1989-11-13 1991-08-28 Toyo Seikan Kaisha Ltd Method of redrawing a metal cap
EP0664169A1 (de) * 1993-12-22 1995-07-26 TOYO KOHAN Co., Ltd Nachziehverfahren
EP0667193A1 (de) * 1994-02-15 1995-08-16 Toyo Seikan Kaisha Limited Verfahren zur Herstellung falznahtloser Dosen

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