EP3188855A1

EP3188855A1 - Method of manufacturing textured - smooth hybrid metal closure caps

Info

Publication number: EP3188855A1
Application number: EP15766910.2A
Authority: EP
Inventors: Laurent LASZCZYK; Christian Delclos
Original assignee: Constellium Neuf Brisach SAS
Current assignee: Constellium Neuf Brisach SAS
Priority date: 2014-09-05
Filing date: 2015-09-02
Publication date: 2017-07-12
Anticipated expiration: 2035-09-02
Also published as: AR101769A1; US20170283126A1; JP6649365B2; JP2017529243A; WO2016034813A1; RU2693976C2; EP3188855B1; CN106687231A; US10787295B2; CN106687231B; FR3025505B1; RU2017111041A3; FR3025505A1; RU2017111041A

Abstract

The method comprises: a) supplying a strip or sheet of aluminium alloy, known to those skilled in the art as a "textured" strip or sheet, typically coated on at least one of its two faces, generally the face intended to be on the inside of the cap, with a coat of deep-drawing boundary lubricant, b) a first operation of cutting into disks known as blanks, c) a step of deep drawing said metal in blank form, in one or more passes typically using a deep-drawing boundary lubricant, so as to form a drawn pre-form, comprising a head and a skirt, typically exhibiting symmetry of revolution about an axial direction, d) a step of degreasing said drawn preform, which step is intended typically to eliminate remains of boundary lubricant so as to form a degreased preform that can be lacquered, e) a possible step of applying a protective and decorative lacquer, and is characterized in that it comprises, after the deep-drawing step and prior to the lacquering step, at least one ironing step consisting in passing the drawn preform through ironing rings in order to stretch out and thin the metal. The invention also relates to a closure cap thus produced. Advantages: the textured appearance is maintained over the entire surface of the head of the cap whereas a smooth or bright appearance is obtained over the entire height of the skirt or wall of the cap.

Description

Method of manufacturing mixed metal textured-filler plug caps

Field of the invention

The invention relates to the field of closure caps comprising an outer metal shell of aluminum alloy and in particular screw caps which comprise an inner insert typically made of plastic and threaded. These capsules are intended for capping containers, mainly glass bottles containing alcoholic beverages and especially wine or spirits.

The invention relates more particularly to a method of manufacturing these capsules to obtain a textured appearance on the top, or head, and smooth or shiny on the "vertical" wall or skirt of the outside of the capsule. State of the art

The aluminum alloy capping capsules are typically manufactured as follows:

- A stamping press forms blanks of capsules from a strip or sheet also called format, cut into blanks, varnished on both sides, with a typical thickness ranging from 0.15 to 0.25 mm without taking into account account varnish. Depending on the height of the skirt (length of the capsule blank), one to three stamping passes may be required.

These blanks are defatted in an oven at high temperature, typically 180 to 210 ° C, for a time ranging from 3 to 5 minutes, to eliminate the stamping lubricant.

- They are then lacquered on their entire outer surface and are put in an oven to cook the lacquer.

These lacquered blanks are printed on the skirt, typically in screen printing, a process known to those skilled in the art under the name "Offset", with a final drying of the inks in an oven. - An overprint varnish is finally applied to protect the printing, said varnish being dried during a passage in an oven.

- The blank thus obtained is provided with a seal and / or a threaded inner plastic insert. It should be noted that all the aluminum alloys referred to below are designated, unless otherwise indicated, according to the designations defined by the "Aluminum Association" in the "Registration Record Series" which it publishes regularly.

Problem

The growing interest in aesthetic solutions has led the Applicant to test the use of aluminum alloy strips known to those skilled in the art as "textured" strip or sheet, that is to say having recessed or raised patterns, typically but not exclusively lines in one or more directions, imparting roughness Ra, measured according to standard NF EN ISO 4287, typically greater than 0.5 or even 1.0 μηι, for stamping blanks of capsules.

This type of surface is well known to those skilled in the art and described in particular in the applications WO 9731783 A1, WO 9508408 A1, US 5857373, EP 0273402 A1 or EP 0456162 A1, CA 2412980 A1, CA 2478648 A1, EP 1368140 Al etc.

However, after the stamping, if the quality of the texture remains substantially unchanged on the head of the blank, it is very degraded and unsightly on the skirt due in particular to the deformation of (or) patterns of texture during said stamping. The valorization of the textured appearance of the initial metal (special grades made by rolling to give a textured and / or iridescent effect on the surface of the metal), is thus made impossible.

No industrially viable solution is known to date to produce textured capsules, whether in whole, or on the skirt and the top, or even partially, only on the top only, because of the aforementioned degradation of the skirt . The invention aims to solve this problem by proposing a method that retains the initial textured appearance over the entire surface of the head of the blank, and smooth or shine over the entire height of the skirt, and this under industrially economical conditions for the bottle closure market of beverage bottles.

Object of the invention

The invention relates to a method of manufacturing metal caps for capping comprising:

a) the supply of an aluminum alloy strip or sheet, known to those skilled in the art under the name of "textured" strip or sheet, that is to say having intaglio patterns or in reliefs, typically but not exclusively lines in one or more directions, conferring roughness Ra, measured according to standard NF EN ISO 4287, typically greater than 0.5 or even 1.0 μιη for stamping, typically coated on at least one of its two faces, generally the face intended to the inside of the capsule, of a layer of stamping lacquer, that is to say which undergoes no deterioration during the stamping, b) a first cutting operation in discs called blanks,

c) a step of stamping and cutting the anisotropic horns, in one or more passes, of said blank metal, typically with the aid of a drawing lubricant, so as to form a stamped blank, comprising a head and a skirt, typically axisymmetric in an axial direction,

d) a step of degreasing, thermally, typically at a temperature of 180 to 210 ° C, for a time of 3 to 5 minutes, or chemical in an alkaline medium, of said stamped blank, intended to typically eliminate the residues of lubricant, for forming a defatted blank that can be varnished,

e) a possible step of varnishing protection and / or decoration,

and characterized in that it comprises, after, optionally chained directly with the drawing step, at least one drawing step of passing the stamped blank through at least one drawing ring in order to lengthen the metal and thin it. Typically, the blank has a thickness of 0.15 to 0.25 mm without taking into account the varnish.

According to the most common mode, the draw ratio (1 - final thickness / initial thickness of the sheet or strip) is greater than or equal to 2.5%.

In a preferred embodiment, it is less than or equal to 30%.

According to a particular embodiment, only the face intended for the inside of the capsule is coated with a varnish before stamping and the face intended for the outside of the capsule is only after the degreasing step.

In another embodiment, the two faces intended for the inside and the outside of the capsule are coated with a varnish before stamping.

Advantageously, the lubricant used for stamping is volatile and removed by heating.

The same applies to the lubricant used for the drawing, which advantageously is volatile and removed by heating, typically in a passage oven or in an oven.

Moreover, the same lubricant can be used for the two stamping and drawing steps.

Advantageously, the drawing and stretching steps are chained in two integrated steps, that is to say without any intermediate step and even more advantageously, they are carried out in one and the same press stroke.

Finally, the aluminum alloy can be, but not exclusively, AA3 type 105 or AA801 type 1.

The invention also relates to a metal closure cap manufactured by the method having one of the preceding features, and characterized in that it has a so-called "textured" appearance on the entire surface of the head or top, and a smooth or shiny appearance over the entire height of the skirt, or wall.

Description of figures

Figure 1 is a schematic section of the capsule used for testing. Its diameter is 33 mm. its height H is 24 mm after stamping, 20 mm after cutting horns of anisotropy and finally 28 mm after stretching, its top or head or "top" is flat and is connected to the skirt or vertical wall A with a radius R of 5 mm.

FIG. 2 shows, from left to right, the top of a textured capsule of patterns in parallel lines after stamping and drawing according to the invention, a view of the skirt of the same capsule after stamping and finally a view of the skirt of the same capsule after stamping and stretching where the textured appearance has disappeared to give way to a smooth or shiny appearance. Figure 3 shows, from left to right, the top of a textured capsule of patterns in perpendicular lines and a view of the skirt of the same capsule after stamping and stretching where the textured appearance has disappeared to give new room to a smooth or shiny appearance. FIG. 4 represents the roughness Ra in microns, measured in the long direction from top to bottom of the wall, for:

The starting sheets, or formats, marked A, shiny or smooth (reference 0), and textured according to different patterns 1, 2 or 3,

Capsules only stamped, marked B, obtained from the formats 0, 1, 2 and 3 above, the measurement being performed on the skirt, from top to bottom of the wall,

The stamped and stretched capsules, marked C, also obtained from formats and capsules B marked 0, 1, 2 and 3 above, the measurement being always performed on the skirt, 1 5 mm from the head of the capsule. Description of the invention

As previously mentioned, because of a growing market interest for aesthetic but economic caps, that is to say a cost compatible with the requirement of the market for beverage bottles and not that of products. cosmetics, the applicant has had the idea to test the use of aluminum alloy strips known to those skilled in the art under the name of strip or sheet "textured", that is to say with patterns hollow or reliefs, typically but not exclusively lines in one or more directions, conferring roughness Ra, measured according to standard NF EN ISO 4287, typically greater than 0.5 or even 1.0 μηι, for stamping the blanks of capsules.

However, it found that after the stamping, if the quality of the texture remained unchanged on the head or top of the blank, it was very degraded and unsightly on the skirt due to the deformation of ( or) texture patterns during said stamping in addition that it presented on the latter a more or less matte appearance. At the same time, the plaintiff had engaged in a program for reducing the thickness of said caps to minimize the amount of metal used. It has thus arrived to proceed to an additional stretching pass after the conventional stamping in one or more passes, the latter leading to a non-uniform skirt thickness which could therefore be optimized to a minimum. This type of stretching, also known as "sizing", is not used in the field of capping capsules and is used to date only in that of cans or bottles-drink.

During tests using so-called "textured" metal, it then unexpectedly found that said texture was preserved on the head, or vertex, of the capsule but completely erased, at the end of said step, on the wall or skirt, while the aforementioned "matte" appearance was improved in a smooth or shiny appearance.

The interest of the invention was therefore multiple: uniformize the thickness of the skirt over its entire height by minimizing the amount of material used, or allowing the manufacture of higher capsules without increasing the amount of material , and finally, get an aesthetic effect with a textured appearance on the top or head and smooth or shiny on the skirt or capsule wall.

The minimum rate of stretching is justified by the fact that the latter must at least bring the thickness of the entire skirt substantially uniformly to the value of the minimum thickness locally obtained after stamping (ie 0.203 mm in the case of Figure 1). The latter depends on the stamping conditions (roughness of the tool, play, clamping pressure, lubrication). This minimum rate is generally considered to be 2.5 or even 3%. The maximum draw ratio is related to the limit of stretch before rupture, intrinsic to the alloy, which must not be exceeded during the drawing, or calibration, of the bottom of the skirt, the thickest zone (of 0.236 mm according to Figure 1). Its value "jeumax" is given by the formula (1 - jeumax) / (1 -LIR) = e _m ax / einit) where LIR is the limit of stretchability of the metal, ema is the maximum thickness of bottom of skirt ( 0.236 mm according to Figure 1) and einit the initial thickness of the sheet (0.21 0 mm in the case corresponding to Figure 1).

In the case of an alloy of the AA3104 or 3105 type, the industrially acceptable stretching limit is 40%. A maximum draw ratio of approximately 30% is then obtained.

In its details, the invention will be better understood with the aid of the following examples, which are however not limiting in nature.

Examples of realization

Stamping step

Alloy metal strips AA801 type 1 known to those skilled in the art under the name of "textured" strip, a Ra roughness of 0.5 μτη to 2.0 μηι, in thickness of 0.210 mm (without varnish) were cut to 210 x 75 mm.

The first stamping pass was made on these unvarnished blanks with the following features:

Diameter of the cutting ring: 64 mm, punch diameter: 33 mm, punch radius: 5 mm, a drawing ratio Re = 0 blank / 0 punch of 1 .94.

The diameter of the matrix was 33.68 mm and its radius 2.5 mm.

The roughness of the surface of the matrix in contact with the metal was Ra = 0.2.

The lubricant was of the type known as KLUBERFOOD NH 1 16-180.

The blanking pressure was adjusted to obtain a cup without creases.

This step made it possible to manufacture cups or capsules as schematically represented in section in FIG. 1, and marked B in FIG. Drawing step

The second stretching pass was made on the cups previously stamped according to step 1 above, with the following features tools:

Punch diameter: 33 mm

Diameter of the drawing ring at 28.6%: 33.30 mm

The diameter of the drawing rings corresponds to a negative clearance with respect to the initial thickness (here metal thickness = 0.210 mm) of metal between the diameters of the punch and the matrix and is calculated as follows:

0 Ring stretching = 0 Hallmark + (2 x metal thickness x (1 - clearance%))

gambling% being the drawing ratio, here 28.6%, ie 0.286

The same lubricant as for the stamping step, "KLBERBERFOOD NH 16-180", has been used successfully whether it is pure or diluted with 80% water.

This step made it possible to manufacture drawn stretched capsules according to the invention, referenced C in FIG.

Results of the tests:

The surface roughness Ra has been used to quantify the criterion of brightness, the latter being all the brighter in that the surface is smooth and thus the roughness is low.

The roughness of the capsule, stamped and stretched according to the invention, was compared with the roughness of the capsule only stamped (according to the prior art), and finally with the initial roughness of the metal in strip or sheet or starting format at flat, before shaping the capsule.

Roughness was measured on flat formats and on the wall or skirt of the capsules from top to bottom of the wall.

The following codes are used:

A: flat format,

B: stamped capsule,

C: capsule pressed then stretched according to the invention. With regard to surface conditions:

0 for the absence of texture, either a glossy or smooth surface,

1 and 2 textures in parallel lines and 3 for two parallel lines of beams crossed at 90 °. Figure 2 shows a capsule stamped in the center and two capsules stamped and stretched on both sides, with the texture 2.

FIG. 4 compares the roughness of the flat format A with the walls or skirts of the capsules A of the prior art and with those of the capsules C according to the invention.

It clearly shows that the invention makes it possible to divide the roughness of the wall by a factor of two to eight.

It shows just as clearly, by comparison between the capsules (A, B) and (C, D), that on the top (or top) of the capsule, the roughness is unchanged, that is to say that The invention does not change the brightness of the top of the capsule. It is greater than the initial roughness of the shiny metal, but remains less than the roughness of a rough milling metal of the type called "Mill Finish".

This point demonstrates the interest of using as a starting sheet, a shiny metal to make the most of the initial shine on the top of the capsule and obtain, by stretching, an improved shine on the whole, including the skirt or wall.

These results are also identical for all the usual criteria for 2D or 3D roughness measurement (Rz, or Sk for example).

Claims

claims

A method of manufacturing metal capping capsules comprising:

a) supplying an aluminum alloy strip or sheet known to those skilled in the art under the name of "textured" strip or sheet, typically coated on at least one of its two faces, generally the face intended for the inside of the capsule, with a layer of stamping varnish,

b) a first operation of cutting into discs called blanks,

d) a step of degreasing said pressed blank, intended to typically remove the lubricant residues, to form a defatted blank possibly to be varnished,

e) a possible step of varnishing protection and / or decoration,

and characterized in that it comprises, after the drawing step, at least one drawing step of passing the stamped blank through at least one drawing ring to elongate the metal and thin it .

2. Method according to claim 1 characterized in that the blank has a thickness of 0.15 to 0.25 mm without varnish.

3. Method according to any one of claims 1 or 2 characterized in that the draw ratio (1 - final thickness / initial thickness) is greater than or equal to 2.5%.

4. Method according to any one of claims 1 to 3 characterized in that the drawing ratio is less than or equal to 30%.

5. Method according to any one of claims 1 to 4 characterized in that only the face for the inside of the capsule is coated with a varnish before stamping and the face for the outside of the capsule does not is after the degreasing step.

6. Method according to any one of claims 1 to 4 characterized in that the two faces for the inside and outside of the capsule are coated with a varnish before stamping.

7. Method according to any one of claims 1 to 6 characterized in that the lubricant used for stamping is volatile and removed by heating.

8. Method according to any one of claims 1 to 7 characterized in that the lubricant used for stretching is volatile and removed by heating.

9. Method according to any one of claims 1 to 8 characterized in that the same lubricant is used for the two steps of drawing and drawing.

10. Method according to any one of claims 1 to 9 characterized in that the drawing and stretching steps are chained in two integrated steps, ie without further intermediate step.

1 1. Process according to any one of Claims 1 to 10, characterized in that the drawing and drawing steps are carried out in one and the same press stroke.

12. Method according to any one of claims 1 to 1 1 characterized in that the aluminum alloy is AA3105 type.

13. Method according to any one of claims 1 to 1 1 characterized in that the aluminum alloy is AA801 type 1.

14. metal corking cap manufactured by the method according to one of claims 1 to 13, characterized in that it has a so-called "textured" appearance, that is to say having patterns recessed or reliefs conferring a roughness Ra, measured according to standard NF EN ISO 4287, typically greater than 0.5 or even 1.0 μπι over the entire surface of the head or top, and a smooth or shiny appearance, that is to say having a roughness Ra, measured according to standard NF EN ISO 4287, less than 0.5 μηι over the entire height of the skirt, or wall.