METHOD FOR PRODUCING AN AEROSOL DOME

TECHNICAL FIELD

[0001]The present invention relates to a method for producing an aerosol dome and to an aerosol dome produced using such a method. In particular, it involves providing a method in which the porosity of the coated material is only increased very slightly, if at all, by the forming process.

PRIOR ART

[0002]Metal cup-shaped objects may be formed from a flat sheet metal portion in a cold forming process. Typically, this takes place after a punching process or in combination with such a punching process in a single forming step (deep drawing), in which the finished component is given its final shape. Such processes are used, for example, for the production of cups, spray cans, components in the automobile industry or in the furniture industry, for food packaging etc. The materials used here are, in particular, aluminum and tin plate.

[0003]In particular, if small material thicknesses are used, the forming process must be conducted carefully in order to avoid cracking, creasing etc. and to thus avoid rejects or inadequate quality. This applies especially to the formation of conical wall regions, since the guidance thereof in the tool is not ensured to the same extent as when forming axially cylindrical wall regions.

[0004]U.S. Pat. No. 4,914,937 proposes a method for shaping a tapered container, in which the container is firstly drawn to a partial length with first and second straight side-wall portions, which are connected to one another by a transition portion, and is then drawn to substantially its final length and its tapered state by drawing material from the transition portion. The method optionally also comprises a second redrawing with an overlength and a base profiling step, in which the over-drawn portion is used to form the profile.

[0005]EP-A-0 310 726 discloses a method for drawing with a cylindrical punch and frustoconical die. According to the invention, the blank is subject to one (or more) drawing procedures between a die with a frustoconical inner wall and a cylindrical punch, wherein the pressure of the clamping means is moderated in order for the metal to adapt to the shape of the die during its deformation. This is applied to the production of can bodies made of “double reduced” sheet metal.

[0006]EP-A-3 702 061 describes a method for producing a component made of metal sheet with a region which is curved or linearly conical, at least in some portions, from a cup-shaped blank with a substantially cylindrical wall portion. The method is characterized in that it comprises at least the following steps:

[0007]draw stages, in which the cylindrical rim portion of the blank is transformed into a region with two cylindrical-portion stages between a drawing die and a drawing punch, which is displaceably guided in a blank holder; at least one subsequent cone draw, in which at least the region with the stages is transformed into a curved or linearly conical component portion between two tools.

[0008]EP-A-1 372 880 and EP-A-3 691 810 describe methods for producing rolled rims. In the case of EP-A-3 691 810, this involves a method for producing a rolled edge from a cylindrical rim portion of a tube, in which a starting region of the rim portion is rolled by a positively controlled tool. A flanging tool is then advanced into the rolled rim region and flanges the rolled rim region to form a roll. The method is characterized in that the tool, which comprises a bending punch and a counter-holder, flanges the starting region of the rim portion at an angle in a range between 75-105 degrees from the axial direction to form a substantially radially circumferential flange.

[0009]WO2019154743 relates to a method for producing a can body consisting of a base and a tubular body from sheet metal, which is coated with a polymer layer on at least one side, in which method a circular disk is firstly produced from the sheet metal, which disk is then deep-drawn to form a pan which has a polymer layer at least on the outside, after which this pan is shaped into a can body by wall ironing. The wall-drawing process takes place in a single stroke by moving the pan successively through a drawing tool and one or more wall-ironing rings.

[0010]KR20090054683 describes a production method for a gas refill tank for preventing hardening of material by producing an upper cap portion and a lower cap portion separately and combining the upper cap portion and the lower cap portion. A production method for a gas refill tank comprises: a step for forming a lower cap via punching and drawing processes after cutting materials according to the standard of a lower end plate using a cutting machine; a step for forming an upper cap in the shape of an upper dome using a press for upper caps; a step for forming a body, including a surface treatment process for removing foreign material and for preventing corrosion; a step for forming a flange for a seaming process by extending the upper and lower side of the tubular body; a step for seaming the lower cap formed at the lower flange; a shimming stage for the upper cap, which is formed on the upper side of the body; and a step for welding a connection which is formed by the adjustment steps.

[0011]DE2816860 describes how the end cap of an aerosol can is pressed from sheet metal, wherein the partially completed workpiece has a planar end face. The end face is removed by firstly producing a circular groove with a V-shaped cross section around the rounded edge. To this end, a tool with a sharp-edged circular hole is used, whilst the cap is held on a mandrel. When the channel has been formed, the flat surface is removed with a punch which is pressed downwards whilst the cap is supported on a hollow mandrel.

[0012]CN-A-102219094 discloses an upper cover of an aerosol tank, a shaping method and a die for a rear taper of the upper cover, wherein the upper cover of the aerosol tank comprises a dome which is generally curved; a recessed notch is arranged in the circumferential direction along the circumference of the curved dome; and the inner wall of the recessed notch has the form of a rear taper. Due to the use of the upper cover of the aerosol tank, a rounded belt weld for an aerosol tank represents an obvious structural requirement; it can be easily and conveniently adjusted and helps to reduce fluctuations in the quality of the tank production so that automatic high-speed production of the tank can therefore run smoothly and the size of the die for an upper cover is reduced so that the overall package is simpler and more attractive. The disclosed die has a simple design and can be processed in a technically simple manner and the round edge of the outer edge of the upper cover may be machined at the same time as the rear taper of the inner wall of the recessed notch, making it suitable for machining and for automatic high-speed production.

[0013]CN-A-520947 describes a production process for tin-plated covers for spray cans, wherein the design and production of molds comprises four separate steps: drawing and correcting the outer diameters and forming, seaming and shaping the central hole and forming the maximum diameter; incorporating the molds for the first drawing step in a deep-drawing press; installing the molds for the last three steps in another press; and automatically conveying material between different steps. Said production process is simple in terms of operation and maintenance, with high material utilization and low production costs.

PRESENTATION OF THE INVENTION

[0014]The object of the present invention is, amongst other things, to provide a method for producing an aerosol dome which enables a dome with the greatest possible stability to be produced with the least possible material (small material thickness) without damaging a paint layer or polymer layer arranged on the material and, in particular, without negatively influencing, i.e. increasing, the porosity of the paint layer or polymer layer located on the material, which may be confirmed by porosity measurements.

[0015]The subject matter of the present invention is therefore a method according to claim 1 or use according to claim 15.

[0016]Specifically, the present invention relates to a method for producing an aerosol dome having a dome region with a rolled rim which adjoins the upper side and is arranged along an upper through-opening and having a flange region with a fold which adjoins the lower side. An intermediate stage is prepared from a paint-coated or polymer-coated blank in one or more stages of the component, which intermediate stage has a base, downwardly followed by a preferably substantially cylindrical neck portion and further followed by the dome region, which is followed by a straight circumferential flange. This intermediate stage is machined in a machining stage in which at least the fold is formed in a deep-drawing process.

[0017]According to the invention, this intermediate stage is machined in a machining stage (S7), in which at least the fold is formed.

[0018]In the machining stage (S7) before the forming process, the intermediate stage bears with the straight circumferential flange on at least three lifting pins, preferably at transportation level, without contacting a push-in sleeve. The intermediate stage preferably bears exclusively on these lifting pins, preferably four lifting pins.

[0019]The component is then guided with its base onto a waste drawing die, advancing from below, by a pressure sleeve and the lifting pins are then in turn moved away and the component lies with the straight circumferential flange exposed (held by the clamping action between the pressure sleeve and the waste drawing die at the base).

[0020]During the drawing of the bowl, the component is preferably lowered onto a folding die without contacting the flange. In this position, the part/the intermediate stage is in turn preferably only clamped between a holding-down device and the folding die; the push-in sleeve is preferably distanced therefrom.

[0021]The fold is then formed. Following the folding process, the component with the fold is lifted to the transportation level from below at the fold by the push-in sleeve for transportation into a subsequent machining station. In other words, the contact with the push-in sleeve takes place for the first time in this machining station and exclusively in this final phase.

[0022]Therefore, in the critical regions of the component to be produced, it is ensured that there is no contact between the guide elements in the tool and the component to be machined that would damage the surface coating.

[0023]According to a preferred embodiment, the proposed method is characterized in that, after the lifting pins, which preferably have a planar bearing face at their upper end (and typically have a circular cylindrical cross section), are moved away and the component with the straight circumferential flange is exposed, the circumferential flange is clamped between a drawing die and a holding-down device before the folding process.

[0024]The fold is then preferably formed when the flange is clamped by lowering an outer drawing punch, wherein, in the first phase of the procedure, the drawing punch is not in contact with the component. Only in the final phase is the fold given its exact shape by the punch.

[0025]The base is preferably punched out in the same machining stage (S7), for example by guiding an inner drawing punch at least partially into the waste drawing die.

[0026]In the proposed process, the position of the lifting pins is preferably controlled via pilot pins preferably provided on an upper part of the tool.

[0027]The push-in sleeve may be in the form of a substantially circular cylindrical element, for example, the upper edge of which only makes contact in the machining stage (S7) when the component with the fold is lifted to the transportation level from below at, or due to the bearing contact with, the fold.

[0028]Furthermore, damage to critical regions of the component may be avoided during the machining thereof, and also in further stations, by designing the gripper, which is used to transport the components to and from this machining station for the folding process or to further machining stations and between further machining stations, as a magnetic gripper. Therefore, contact between such grippers and the component only takes place via magnetic force and as flat contact without friction.

[0029]Therefore, the method is preferably characterized in that the component, during its transportation from a previous machining stage into the machining stage (S7) for the folding process and/or during its transportation from the machining stage (S7) for the folding process into a subsequent machining stage, is gripped with the aid of magnetic grippers. The transportation between further machining stages, in particular all machining stages, after the machining stage in which the rim of the flange is cut to its final contour preferably also takes place with the aid of magnetic grippers.

[0030]The magnetic grippers preferably lie opposite one another in pairs and are preferably arranged on feed rods of a transfer system in a rigid and non-spring-loaded manner.

[0031]The magnetic grippers preferably have at least one magnetic element, preferably in the form of a permanent magnet element or an electromagnetic element, wherein the grippers are preferably designed such that the magnetic element is in flat contact with the flange at its upper side during transportation.

[0032]Such a method is preferably furthermore characterized in that the intermediate stage has an outwardly curved undulation at the transition from the dome region to the neck region.

[0033]Preferably, at least one further stage, in which a rolled rim is formed from the neck portion, directly or indirectly follows the machining stage for generating the fold.

[0034]According to a further preferred embodiment, at least one further stage, in which a preliminary stage or the final rim curl is generated from the remaining flange, directly or indirectly follows the machining stage for generating the fold, wherein this further stage, if only one preliminary stage is formed, is preferably carried out in combination with a stage in which a rolled rim is formed from the neck portion, and wherein this stage is then preferably followed by a further stage, in which the rim curl is formed. There are then preferably no more following steps.

[0035]The paint-coated blank is preferably produced in the shape of a cup with a circumferential flange, a rounded region and a base, but without a neck region, and, in at least one first stage, this blank is formed to the required partial height H (typically in the range between 10-40 mm) before generating a rolled rim with an axial neck region, and the radius at the transition region between the flange and the rounded region is preferably furthermore reduced in this first stage, preferably to a radius in the range between 0.2-1.0 mm, in particular preferably in the range between 0.3-0.6 mm.

[0036]After the first stage, in at least one, preferably in two further stages, a second stage and a third stage, the neck region may be further shaped, in particular the radius of the region between the axial neck region and the radial base may be reduced, preferably to a sharp edge with a radius in the range between 0.05-0.6 mm, in particular preferably in the range between 0.1-0.2 mm.

[0037]According to a further preferred embodiment, in the folding stage or a stage following this, the base, which has possibly been prepared by scoring, is guided out of the tool as a bowl to form an upper through-opening, or punched out to form the upper through-opening, and then, in a sixth stage, the circumferential edge formed as a result is preferably turned to form a collar, wherein the fifth stage and the sixth stage are furthermore preferably implemented after the two further stages, as stated above.

[0038]It is furthermore preferred if, in one stage, preferably in the fifth stage according to the description above, an outwardly curved undulation is formed in the dome region, at the transition from the dome region to the neck region.

[0039]In one stage, preferably in the second stage and/or the third stage and/or the fourth stage, scoring may additionally take place in the transition region between the base and the neck region in order to prepare for the removal of the base.

[0040]A further preferred embodiment is characterized in that, to produce the rolled rim from a cylindrical rim portion of the neck region in a first step, preferably in the fifth stage as stated above, a starting zone of the rim portion is turned by a positively controlled tool to form a collar and, in a second step, preferably in the further stage as stated above, a flanging punch then moves into the turned rim portion and flanges this to form a roll, wherein, in the first step, the starting zone of the rim portion may be turned through an angle in the range between 75-105°, preferably in the range between 80-100°, or in the range between 85-95°, from the axial direction by the tool comprising a turning punch and counter-holder to form a substantially radial circumferential flange.

[0041]The bending radius between the circumferential flange and the axial portion adjacent thereto is preferably smaller than double the material thickness of the cylindrical rim portion; the bending radius is preferably in the region of 0.5-1.5 times, in particular preferably in the region of 0.75-1.25 times the material thickness of the cylindrical rim portion.

[0042]The radial length of the flange is furthermore preferably in the region of 2-5 times, preferably in the region of 3-4 times the material thickness of the cylindrical rim portion.

[0043]The material of the blank is preferably provided with a dense paint layer on both sides or at least on the future upper side (outer face 7). The paint may be provided directly on the metal or via an additional adhesive layer. This is preferably a polyester paint, an acrylate-based system or a methacrylate-based system or a polyurethane paint. Such a paint may be water-based or solvent-based and it may be cross-linked. The paint applied is preferably zero VOC.

[0044]The blank may also be provided with a dense polymer layer or plastic layer or with a plurality of such layers. There are then usually additional adhesive layers between the metal and the at least one plastic layer. The plastic layer may consist of polyethylene terephthalate (PET) or polypropylene (PP) or polyethylene (PE) or a mixture of such systems. The plastic layer may additionally contain the usual additives (in particular plasticizers, fillers) and, especially, colorants or pigments in the usual proportions, where appropriate.

[0045]The thickness of such a paint layer or plastic layer is preferably in the range between 5-40 μm (including an adhesive layer, where appropriate).

[0046]The material thickness of the blank is typically in the range between 0.1-1 mm, preferably in the range between 0.15-0.4 mm, in particular preferably in the range between 0.18-0.34 mm.

[0047]The material of the blank is preferably steel sheet, preferably tin plate. However, aluminum is also possible.

[0050]Or the material of the blank (R) is steel sheet, preferably tin plate of type TH520, material number 1.0384; TH550, material number 1.0373; TH580, material number 1.0382; TH620, material number 1.0374, or the corresponding TS-types, each according to DIN EN 10202: 2001 and/or DR8, DR8, DR8.5 or DR9, each according to AISI/ASTM 623.

[0051]Furthermore, the present invention relates to the use of such a method for producing an aerosol dome for a spray can.

[0052]Furthermore, the present invention relates to a tool for carrying out such a method.

[0053]Finally, the present invention relates to and describes an aerosol dome for a spray can produced according to a method as stated above or in a tool as specified above.

[0054]Further embodiments are specified in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0055]Preferred embodiments of the invention are described below with the aid of the drawings, which serve merely for explanation and should not be interpreted as restrictive. In the drawings:

[0056]FIG. 1 shows a sequence of stages for producing an aerosol dome from a cup-shaped blank;

[0057]FIG. 2 shows, in a), the situation during the conventional pushing-out of the component and, in b), the situation during the conventional pushing-in of the component;

[0058]FIG. 3 shows, in a), the open tool according to the new method and, in b), the closed tool according to the new method;

[0059]FIG. 4 shows, in a), a lateral view at the time when the component is placed on the lifting pins and, in b), a plan view of the situation when the component is placed on the lifting pins;

[0060]FIG. 5 shows the tool in the situation in which the component is clamped between the pressure sleeve and the waste drawing die in the base region;

[0061]FIG. 6 shows the situation before the drawing punch draws the bowl into the waste drawing die;

[0062]FIG. 7 shows the pilot control of the lifting pins;

[0063]FIG. 8 shows the situation shortly before the folding process;

[0064]FIG. 9 shows the tool in the lower dead center during the folding process;

[0065]FIG. 10 shows the tool when the part is lifted;

[0066]FIG. 11 shows the component with magnetic grippers in a perspective view;

[0067]FIG. 12 shows the tool with the magnetic grippers in the set-down position.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0068]To produce an aerosol dome from a cup-shaped blank R made of a thin paint-coated material, a plurality of stages are implemented according to the invention.

[0069]A possible method is described in association with FIG. 1.

[0070]A cup-shaped blank R produced in a prior punching and forming process is supplied to the process as illustrated by arrow 21. However, it is also possible for the production of this cup-shaped blank R, which is typically firstly punched out of a flat raw material supplied in strip form and then deep drawn to form a pan, which may take place in one or two steps, to be carried out in the series of stages, described here, as the first step.

[0071]This blank R, illustrated in a), has a circumferential flange 15, which transitions into a rounded region 17 via an initially cylindrical region 53 and which has a closed base 18.

[0072]In the machining process (illustrated by the arrow 22) in the first station S1, this blank R is subject to a first drawing process Z1, wherein a punch is moved into the interior of the blank and the blank is pressed against a die. This results in the component illustrated in b). In this step, the cylindrical region 53 and parts of the rounded region 17 are transformed into a dome region 5, and a neck portion 14 is formed from parts of the rounded region 17 and the base 18, which neck portion follows a transition 20 to the dome region 5. The base 18 is given a relatively small diameter and a roundness 19 is established at the transition from the base 18 to the neck portion 14. The flange 15 substantially remains and the component is not yet at its final height; this is only established in following steps.

[0073]In a step RP illustrated by arrow 23, the rim is then cut, i.e. the radial length of the flange 15 is set to the desired value; this step takes place in the stations S2 and S3 (one of these being an idle station) and this results in the component according to c).

[0074]In the machining process (illustrated by the arrow 24) in the fourth station S4, this component is subject to a second drawing process Z2, wherein a punch is in turn moved into the interior and the component is pressed against a die. This results in the component illustrated in d). In this step, the dome region 5 is formed and increased and the neck portion 14 is extended and its radius reduced.

[0075]In the machining process (illustrated by the arrow 25) in the fifth station S5, this component is subject to a third drawing process Z3, wherein a punch is again moved into the interior and the component is pressed against a die. This results in the component illustrated in e). In this step, substantially only the previously rounded region 19 is shaped into a substantially sharp edge 31 at the transition from the neck region 14 to the base 18.

[0076]In the machining process (illustrated by the arrow 26) in the sixth station S6, this component is subject to scoring Ri, i.e. in the region of the transition 31 between the base 18 and the neck region 14, circumferential scoring is generated, the function of which during the further machining process is as follows: The base is prepared in order to be broken away in the subsequent station and guided out of the tool, drawn as a bowl. This results in the component illustrated in f).

[0077]The component, as illustrated in FIG. 1f), is also referred to below as intermediate stage 54. It is notable in that it has a circumferential planar flange 15, which transitions into a curved (convex as seen from the inside) region into the dome region 5; this in turn transitions into a curved (convex as seen from the inside) region into a cylindrical neck portion 14 and this neck portion 14 is terminated at the top by the base 18. The transition between the base 18 and the neck portion 14 here is preferably formed as a sharp edge 31 and already has said scoring.

[0078]In the critical machining process (illustrated by the arrow 27) in the seventh station S7, this component is subject to a plurality of steps U at the same time. On the one hand, a fold 3 is generated from parts of the dome region 5. This fold transitions into the flange 15 via a vertical portion 9 and radially inwards into the dome region 5 via an adjacent region 8. As a result of the material thickening (compression) caused by this type of forming process in combination with the bearing contact against the push-in sleeve, there is a high load on the coating which may result in flaking of the coating layer, specifically in the region which generally comes into contact with the filling medium. At the same time, in this step, a slight outwardly directed undulation 13 is optionally formed in the dome region 5, which undulation is adjacent to the neck portion 14. Likewise at the same time, in this stage, the base, which was prepared in station 5, is optionally guided out of the tool as a bowl, so that there is a through-opening 32 at the top, as well as a free straight edge 16 of the cylindrical portion 14, and the component height is established. This results in the component illustrated in g).

[0079]In the critical machining process A (Illustrated by the arrow 28) in the eighth station S8, this component is subject to die bending A. That is to say a starting zone of the rim portion 16 is turned by a generally positively controlled tool and only then is a flanging punch moved into the turned rim portion in a second step during the subsequent stage S9 and this rim portion flanged to form a roll (rolled rim) 2. In this step S8, the starting zone of the rim portion 16 is turned by a tool comprising a turning punch and counter-holder through an angle in the range between 75-105° from the axial direction to form a substantially radial circumferential flange 12. This results in the component illustrated in h).

[0080]In the machining process W (Illustrated by the arrow 29) in the ninth station S9, the rolled rim 2 is formed in this component on the one hand and the radial circumferential edge of the flange 15 is turned downwards in a preliminary stage 11 on the other, so that a horizontal flange portion 10 remains. This results in the component illustrated in i).

[0081]Finally, in the machining process RC (illustrated by the arrow 30) in the eleventh station S11, the final rim curl 4 is generated.

[0082]In this series of stages for producing the aerosol cover, the flange 15 is folded.

[0083]In aerosol covers produced in this way, surface damage may occur due to the production process. However, depending on the use of the can, e.g. in the food industry, this must be avoided since the cover begins to rust in the event of significant surface or paint damage. This can be shown/measured via porosity measurements.

[0084]Analysis of the situation has surprisingly shown that this damage may be promoted during the forming of the part and during partial transportation. More precisely, this is promoted by the push-in sleeve during the folding of the part and is further reinforced by the engagement and disengagement of the part in the spring-loaded latching devices of the feed rod which conveys the part between the forming steps by means of the tool. The critical region for the application is, especially, the inner rim region and also the outer rim region in the case of the rim curl 4, the horizontal flange portion 10, the fold 3 and parts of the inside and outside of the dome region 5 adjacent to the fold 3.

[0085]In the analysis, two weak points were recognized individually and, in particular, in combination with regard to the paint problem. These are:

[0086]1. The initial contact with the push-in sleeve during the folding process.

[0087]2. Further promoted by the constant contact with the spring-loaded latching grippers during transportation of the part by means of the tool.

[0088]The sequence during the folding process, i.e. in the operation outlined above, in the station S7 along arrow 27 in FIG. 1 is as follows:

[0094]The initial contact here is in the curved region at the inner transition between the flange 15 and the dome portion 5 and at the push-in sleeve. Based on the required shaping of the part from the previous forming stage, this initial contact is not precisely defined and linear bearing contact is realized over the diameter of the part and the push-in sleeve. Due to the determinative drawing die and the lifting function, the push-in sleeve cannot be designed differently in this station. In addition, this constant contact with the push-in sleeve continues during the forming process and may therefore negatively influence the surface coating.

[0095]As the component is pushed into and out of the latching devices/grippers of the feed rod in the transfer tool, a recurrent frictional contact point along the latching faces sometimes additionally occurs. This is problematic particularly in the stations downstream of the folding process. With eight forming stations with a feed rod equipped with latching devices, the component is pushed into and out of nine latching devices. Therefore, from the blank to the finished cover, it is pushed in and out 18 times, always in the same position, and the paint or the surface of the part is thus weakened or even damaged. The conventional sequence is illustrated in simplified form in FIG. 2 a and b.

[0096]FIG. 2a) shows the situation during the pushing-out of the component in station S7. During the pushing-out of the component 42, the pressure sleeve 33 moving downwards ensures that the spring-loaded latching devices or grippers 35 snap open. The flange 15 of the component 42 and the downwards movement of the upper part 38 of the press ensure that the latching devices 35 open. Once the component 42 has passed the shoulder on the latching device 35, which is responsible for secure transportation, the latching device 35 snaps shut again with the spring deflection of the gripper 35. There is constant contact with the contact faces 36 so long as the component 42 is in the region of the latching devices 35.

[0097]During the pushing-in of the component into the latching devices 35, as Illustrated in FIG. 2b), the behavior is similar to that for the pushing-out of the component. The only difference is that, here, the push-in sleeve 34 moving upwards from below ensures that the latching devices 35 snap open. The upper part 38 is inevitably in reverse motion due to the press stroke. After the component 42 has reached the transportation level, the latching devices 35 snap shut again and hold the part reliably for transportation via the spring force.

[0098]In general, in association with the figures, it should be noted that the same reference signs denote the same elements or parts thereof; for the sake of clarity, the elements of the tool that are denoted in the figures are not all explicitly mentioned within the context of all subsequently described figures; the functionality of the elements as a whole, however, is revealed to a person skilled in the art from the overall context of the description.

[0099]Preventing contact between the component and the push-in sleeve is not obvious since this push-in sleeve is needed to lift the part to the transportation level and must therefore be, and remain, part of the system.

[0100]In the proposed folding station S7 described in association with the following figures-cf. FIG. 3a), which shows the tool in the open position with the inserted component 42 according to FIG. 1f), and FIG. 3b), which shows the closed tool in the lower dead center with the folded component according to FIG. 1g) held therein—the component 42 with the flange 15 is placed at least partially on lifting pins 41, typically four thereof distributed around the circumference, in order to avoid the above-described negatively acting contact face or the contact line with the push-in sleeve 34 in the convexly curved region between the flange 15 and the dome 5. The entire unit in the lower part 39 is then driven back over the component via the pressure sleeve 34 and the two pilot pins 37 in the upper part 38. During this, the press moves downwards between the angles 0°-180°. The folding station Illustrated in FIG. 3a) corresponds substantially to the overall illustration of the folding station. The tool is shown open here. In the further figures, some parts are shaded out for simplification of the detailed sequence description.

[0101]The closed tool is depicted in FIG. 3b). In this situation, the forming of the component is completed and the lifting of the component 42 is initiated by the upward press stroke between 180°-360°. The elements in the lower part 39 of the tool which are positively controlled by the pressure sleeve 34 and the pilot pins 37 can be seen here.

[0102]The detailed sequence during the folding process and the positioning of the component can be described as follows:

[0103]FIG. 4a) shows a lateral view of the set-down component 42 and FIG. 4a) shows a plan view. The component 42 now bears, at certain points, with the underside of the flange 15 on the lifting pins 41 or on the surface 49 thereof and is no longer supported from below by the push-in sleeve 34 in the critical curved region on the inside between the flange 15 and the dome region 5. As a result, said problems caused by this contact line are avoided, as outlined above, since the flat bearing contact between the underside of the flange 15 and the upper face 49 of the lifting pins 34 leaves the coating of the material undamaged. It is ensured in the process that the uppermost edge of the push-in sleeve 34 lies below the component with a sufficient gap during the entire process and the contact is only established when the push-in sleeve 34 is used to displace the component upwards from below via the lower curvature of the fold 3 (cf. below).

[0104]The incoming component 42 is placed on the lifting pins 34 by the pressure sleeve 43. These lifting pins are then driven back as a result of the downwards movement of the press. At the gap between the component 42 and the push-in sleeve 34, it can be seen that four lifting pins 41 protrude with respect to the push-in sleeve 34. As a result, the undefined initial contact, as described above, is avoided. The bearing region across the four lifting pins 41 is defined and is not critical in terms of damaging the part.

[0105]This may be understood in detail in particular with the aid of FIG. 5 and the following figures. FIG. 5 shows the moment at which the component 42 is clamped by its base 18 between the pressure sleeve 33 and the waste drawing die 43. The pressure sleeve 33 drives the component 42, still bearing on the four lifting pins 41, back as far as the waste drawing die 43. The spring-deflection of the pressure sleeve 33 then inevitably begins.

[0106]FIG. 6 shows the situation directly before the drawing punch 24 draws the typically already scored base 18 into the waste drawing die 43 when the two pilot pins 37 of the upper part 38 move towards the pressure pins 40 of the lower part 39 and control the displacement of the lifting pins 41. The component 42 is now completely exposed and is only still held between the pressure sleeve 33 and the waste drawing die 43 until the base/bowl is drawn away.

[0107]FIG. 7 shows, in a detail, the situation in which the pilot pins 37 are now moved towards the pressure pins 40 and the lifting pins 41 have moved downwards, away from the underside of the flange 15, so that the bearing face 49 is now no longer in contact with the underside of the flange 15. In this state, the upper side of the flange is already in contact with the lower face of the holding-down device 46.

[0108]FIG. 8 now shows the situation when the bowl/base is drawn out. The component 49 is pushed backwards onto the drawing die 47. The component is then clamped between the drawing die 47 and the holding-down device 46. The spring-deflection of the holding-down device 46 begins. The pilot pins 37 ensure that the displacement of the push-in sleeve 34 and the lifting pins 41 remains continuously controlled. The actual folding process begins, driven by the outer drawing punch 45 moving downwards. Since the forming process takes place exclusively via the active elements, undesired contact, which may damage the surface of the component, does not occur. This is also confirmed by porosity measurements, which were carried out directly after this forming process and compared with the old forming methods.

[0109]FIG. 9 shows the situation in which the press is at 180° in the so-called lower dead center. The forming of the component is completed and the press ram opens again. The sequence now takes place in reverse. The difference here is that the component now comes into contact with the push-in sleeve 34 for the first time (cf. also FIG. 10) in order for it to be lifted to the transportation level of the feed rod so that it may be taken over by the magnetic grippers described below.

[0110]With the previous feed rod, the part was always latched into and unlatched from the latching devices during the production process of the aerosol cover and recurrent frictional contact occurred as a result. According to a further aspect of the present invention, the part is conveyed through the tool by magnetic grippers as soon as the rim is cut; i.e. from station S2/S3 until the aerosol cover is finished. These magnetic grippers are constructed so that there is no contact at all at the critical points. They contain a magnet 53, the cover plate or holding projection 51 and the gripper 50 itself, cf. FIG. 11. The grippers are, moreover, not integrated in the feed rod in a spring-loaded manner, but in a rigid manner.

[0111]FIG. 12 shows the position at the end of the feed process. The grippers 50 here are in a detent position, which means that they are held stationary above the center point of the respective forming station. This position corresponds to the set-down position illustrated in FIG. 4. During the transportation between the forming stations, the magnetic grippers draw the part to at least 0.5 mm above the level of the push-in sleeve 41 in order to ensure that unwanted contact does not occur during transportation. In addition, the grippers are constructed so that, during the release or lifting of the component from or into the grippers, contact does not occur between the component and the grippers 50; only contact between the component and the flat underside of the magnetic element 53 is possible at the moment when the component is held by the grippers. The shape of the grippers 50 serves to ensure that they do not lose the component when the feed rate is accelerated. This may be ensured due to the accuracy of the system and the manufacturing accuracy of the grippers.

[0112]The magnetic grippers are used in the process as follows: The tool upper part 38 moves downwards. As soon as the pressure sleeve 33 contacts the component 42, the latter is released from the grippers, which remain rigidly in position. The magnets 53 incorporated in the cover plate 51 lose their holding force over distance. At this moment, as already mentioned, there is no contact with the conveyed part. The further the upper part 38 is retracted, the further the part moves away from the contact zone of the grippers. For additional security, run-in faces on the grippers serve to advance the part gently if it is not in the exact desired position. After the forming process, the push-in sleeve 34 lifts the part 42 back to the transportation level. From here, the magnets draw the part back against the cover plate 51 in order to achieve the minimum safety distance of 0.5 mm during transportation.

[0113]These grippers are installed in the feed rod, which is in turn coupled to the gear of the press. As previously, the first two stations may be installed as spring-loaded latching devices. Since the region which comes into contact with the latching devices is removed in station 2 by cutting the flange, this still has no influence on the porosity of the aerosol cover. The magnetic grippers only come into use once the flange diameter has been defined by cutting.