Patent Publication Number: US-2010116775-A1

Title: Multi-color printed and embossed lid for cream jars and method for producing such lids

Description:
Jars as packaging are sufficiently well known. They can be made from different materials, such as sheet metal, wood, plastic. Sheet-metal jars can be produced from different metals, for example, from aluminum, steel, brass. The jar can be produced from the metal by means of trimming to size, folding, flanging or soldering or welding. Another method is cold working, in particular deep drawing. The joining of sheet metal edges is dispensed with thereby. 
     A jar can be closed by a lid. Lids are conceivable in many different designs: there are hinged lids (box of cigars), screw lids (oil jar), push-on lids (tea jar, cookie jar or Nivea jar). The lid can also be firmly attached to the jar, as in the case of a canning jar. 
     The jar and/or lid are often designed for advertising purposes. To this end the wall material can be coated with varnish and paint, polished, labeled and/or embossed, depending on the manufacturer&#39;s requirements. An interior coating with varnish and paint, metal or plastic can also be provided. 
     Jars can have many conceivable shapes: in plan view they can be rectangular, oval, round, octagonal, star-shaped or irregularly shaped (e.g., “Garfield” the cat, “Mickey Mouse”). 
     Most jars for practical use have a right angle between the jar base and wall, which keeps the space requirement low for shipping a plurality of jars in a case. However, the lid is often not flat on the top, but more or less curved. 
    
    
     The subject matter of this invention are jars, the lids of which are designed in a multi-colored manner and embossed, in particular varnished and printed lids with lettering, which is designed in a multi-colored manner as well as emphasized by embossing. In particular the invention relates to lids that are deep-drawn from aluminum, round, curved and can be produced in mass production. 
     The production of painted and deep-drawn aluminum lids is known per se. Production methods with high throughputs use a combined cutting, drawing, rolling tool. 
     A tool of this type is driven via a crankshaft and permits the production of  200  lids per minute on average. For each stroke, one lid is punched out of a sheet-metal plate and subsequently deep-drawn. The remaining edges on the lid edge are rolled so that the finished lid can be blown out. 
     A suitable tool is shown in  FIG. 1 . The movements of the tool during a cycle are likewise shown. The figure thereby shows the principle of a conventional cycle as well as of a cycle according to the invention. 
     The tool comprises a bottom die ( 1 ), ( 2 ), ( 3 ) and an upper die ( 4 ) and ( 5 ). The bottom die has a core ( 1 ), a die ring ( 3 ) and a so-called blank holder ( 2 ). The blank holder ( 2 ) has a rolling ring ( 2   a ) on the top facing towards the core ( 1 ). 
     The upper die comprises a male die ( 4 ) and an ejector ( 5 ), around which the male die ( 4 ) is oriented. A combination of this type of upper die and bottom die is shown in  FIG. 1 . The upper die is driven by a crankshaft. At the upper dead-center position) (0°) the tool is at its highest position during a cycle. 
     After the sheet-metal plate has been guided over the bottom die, the cycle begins ( FIG. 1A ): The upper die is lowered onto the bottom die and grips the sheet-metal plate with the male die ( 4 ) and presses it onto the blank holder ( 2 ). This occurs with a crankshaft position of approximately 135° ( 6/8 stroke). 
     When the movement of the crankshaft continues further ( FIG. 1B ), the blank holder ( 2 ) is slowly lowered, whereby the die ring ( 3 ) cuts a circular blank out of the sheet-metal plate (likewise 135°). 
     In the further course of the cycle up to the lower dead-center position ( FIG. 1C ), the male die ( 4 ) and blank holder ( 2 ) gradually advance downwards, whereby the lid is slowly formed from the circular blank over the core ( 1 ). Material thereby slides through slowly between the blank holder ( 2 ) and the male die ( 4 ), whereby the side wall of the lid is formed. After approximately ⅞ of the stroke, the ejector ( 5 ) is placed on the core ( 1 ) in a spring-loaded manner. Now the top of the lid is formed between the core ( 1 ) and the ejector. 
     During the last ⅛ of the stroke ( FIG. 1D ), the ejector ( 5 ) is stationary, the male die ( 4 ) continues moving. At the lower dead-center position (180°), a hat-shaped structure is formed. The hat brim thereby remains between the core ( 1 ) and male die. 
     In the upward movement again after passing through the lower dead-center position of the crankshaft ( FIG. 1E ), first the blank holder ( 2 ) is conveyed upwards, whereupon the male die ( 4 ) slowly yields backwards, but the ejector ( 5 ) remains stationary for ⅛ of the stroke. The remaining hat brim is thus pressed into the rolling ring of the blank holder and shaped to form a roller-shaped edge of the lid. This all happens between a crankshaft position from 180 through about 200°. 
     Subsequently, the upper die is removed from the bottom die again ( FIG. 1F ) and takes the lid with finished shape with it ( FIG. 1G ). This lid is blown out from the tool through an ejector stroke and an air flow ( FIG. 1H ) at a crankshaft position between 330 and 360°. 
     A modern machine permits about 200 strokes per minute, thus about 12,000 lids per hour can be shaped with one tool. Generally, 3 to 5 tools are used simultaneously, whereby 36,000-60,000 lids can be produced per hour. 
     With such high throughputs, the sheet-metal plate must be guided very exactly under the tools located at the upper dead-center position. Furthermore, it must be ensured that the spacing between the male die ( 4 ) in the upper ring and die ring ( 3 ) in the bottom die peripherally is about 3 1/100 mm=30 μm. It must likewise be ensured that the drawing gap, that is, the space between the core ( 1 ) and the blank holder ( 2 ), is exactly the sheet metal thickness. This is not a trivial function in the case of the very heavy tools exposed to high dynamic stresses. Conventional upper dies are therefore generally arranged in a rotatable manner, because this considerably facilitates the alignment of the upper die to the bottom die for adjusting a correct drawing gap. 
     In addition to the male die ( 4 ), the ejector ( 5 ) is a highly loaded tool part. This tool part has different bores that render possible the attachment, dismantling and ventilation of the tool. In a conventional manner, the bores and ventilation holes are distributed in the ejector ( 5 ) over virtually the entire area of the ejector ( 5 ). As a rule, 8-12 bores are provided. 
     However, no bores can be provided on the outer annular area of the ejector oriented towards the male die ( 4 ). This area represents a further clamping area of the tool, which is necessary for absorbing the compressive forces during the rolling process between the core ( 1 ) and the ejector ( 5 ). 
     If an additional embossing of the lid is also provided, the lid must be separately embossed once again in a subsequent process step after ejection from the cutting/drawing/rolling tool. It is relatively easy, if the embossing does not have to be carried out in an aligned manner, e.g., if an embossing of any orientation is simply to be carried out on a single-color lid. 
     However, it becomes very complex when the embossing may have only a single position of the lid on the embossing tool, if, e.g., a lettering is to be emphasized by the embossing as well as by the imprinting, such as, e.g., in the case of a blue jar lid with “Nivea” in white lettering, where the lettering in addition is to be embossed over the entire area. 
     The alignment is hardly possible mechanically and would have to be done by hand. This may be the reason why lids of this type that are embossed and imprinted hitherto have not been available on the market at all. 
     An integration of the embossing step into the described automated cutting, drawing rolling process is not easily accomplished either: 
     On the one hand, the free rotatability of the upper die, which is necessary for the alignment of the upper die to the bottom die, does not allow a lettering to project, since the rotation can result in positions in which the positive embossed shape does not coincide with the negative embossed shape on the upper die or bottom die. This leads to damage to the embossing dies during a throughput cycle. 
     On the other hand, there is no room at all for lettering on the ejector ( 5 ) of the upper die due to the numerous bores, which are used for ventilation and attachment purposes. 
     Furthermore, the embossing pressure and embossing time must be sufficient to be able to emboss the very elastic aluminum at all. The aluminum—Mg-containing Al alloys are used, which are considerably more elastic than pure Al—tends to spring back to the initial shape in the case of an embossing force action of only short duration, whereby the freshly embossed edges easily become round or flat. This is no problem at all with sheet steels, because steel is much more easily malleable. 
     Furthermore, with the in-process embossing of an aluminum lid, the so-called frog effect occurs: through material tension, during movement the lid tends to make a noise that is reminiscent of a snap-action toy and makes a very audible “plop” sound. However, this is extremely undesirable. 
     Furthermore, the tool must be designed such that unembossed lids can also be produced easily. A tool that can be used exclusively for embossed lids represents an excessively high expense for a process of this type. 
     The tool must therefore be provided such that it can be converted to a standard tool without an embossing punch by just a few actions. 
     This bundle of objectives is attained through a method for producing printed and embossed deep-drawn aluminum lids that are circular in plan view, characterized by a sequence of the following process steps:
         a) coating, in particular printing, an aluminum plate with varnish and/or paint,   b) cutting the aluminum plate,   c) deep drawing,   d) embossing,   e) optionally edge rolling, wherein the steps (b), (c), (d) and optionally (e) are carried out with a single tool. The invention also comprises a varnished, printed and embossed deep-drawn aluminum lid that is circular in plan view, substantially in the shape of a cylinder open on one side, in which the printing on the substantially flat surface has at least one contour that also represents the contour of the embossing, obtainable through a sequence of the steps referenced in the previous sentence.       

     Through the method according to the invention it is possible to integrate the embossing operation into the cutting/drawing/rolling operation in a single-step process. The embossing force is sufficient to emboss clean edges. It is easily possible to align the embossing with the pre-painted lettering, because the sheet-metal plate is guided through under the embossing die only once by a two-axle servo system. Through the special design of the ejector, it is possible to produce these jar lids free from the frog effect. Furthermore, the embossing dies recessed in the tools can be easily replaced by non-contoured dies. It is thus possible to produce unembossed lids on the same tool. 
     It is preferred if in all this the dimensional variation between the contour of the painting and the contour of the embossing is no more than 0.3 mm. It is preferred if the tool comprises an upper die and a bottom die, which are driven by a crankshaft and the bottom die has at least one core ( 1 ), a blank holder ( 2 ) with integrated rolling ring ( 2   a ) and a die ring ( 3 ), the upper die has a male die ( 4 ) and an ejector ( 5 ) and the ejector has an embossing tool in the area of its center, ventilation and mounting bores outside the embossing die and an annular clamping area ( 6 ) near to the edge, the edges of which have a spacing of at least 8 mm and which is free from bore holes and mounting holes, wherein the upper die is not freely rotatable and on the bottom die likewise has an embossing die, wherein the embossing dies are aligned to one another and are recessed in the ejector and core ( 1 ). 
     It is further preferred thereby if the process steps take place as follows: (b) cutting the aluminum plate 135 to 145° after upper dead-center position, (c) deep drawing 140 to 170° after upper dead-center position, (d) embossing 170 to 180° after upper dead-center position, (e) optionally edge rolling 180 to 200° after upper dead-center position and (f) optionally blowing out 330 to 360° after upper dead-center position, in each case based on the position of the driving crankshaft. Furthermore, it is preferred if the embossing die is provided on the core ( 1 ) with two mounting bores and two ventilation/ejector bores. It is very particularly preferred if the tool has gap widths between the bottom die and the upper die and between the male die ( 4 ) and the blank holder ( 2 ) and core ( 1 ) of 20 to 40 μm. Furthermore, it is particularly preferred if the tool has an ejector which is arranged with respect to the later lid shape towards the open side of the lid at least with 50% of its area by 0.4 to 0.9 mm. It is particularly advantageous if the production is carried out on a tool with throughputs of at least 150, particularly preferably at least 190 pieces/min. It is thereby very advantageous if the lid is made of an AlMg alloy with 2.5% Mg. The invention also comprises a jar containing a cosmetic preparation, in which the lid was produced as described above.