Patent Application
20220395887
The present invention relates to a method for producing an aerosol dome and to an aerosol dome produced using such a method.
Pot-shaped articles made of metal can 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 provided with its final shape. Such processes are used for example for the production of pots, spray cans, parts in the automotive industry or in the furniture industry, for food packaging etc. As materials, use is made in particular of aluminium and tinplate.
In particular when small material thicknesses are used, the forming process has to be carried out carefully, in order to avoid the formation of cracks, folds, etc. and thus scrap or insufficient quality. This is the case especially for the formation of conical wall regions, because, for the latter, in contrast to the formation of axially cylindrical wall regions, guidance in the tool is not ensured equally.
U.S. Pat. No. 4,914,937 proposes a method for forming a tapering container, in which the container is initially drawn to a partial length with first and second straight side-wall portions, which are connected together by a transitional portion, and is then drawn into more or less its final length and its tapered state by drawing material from the transitional region. The method optionally also comprises second redrawing with an overlength, and a bottom profiling step, in which the overdrawn portion is used to form the profile.
EP-A-0310726 discloses a method for drawing with a cylindrical punch and a frustoconical die. According to the invention, the blank is subjected to one (or more) drawing operations between a die with a frustoconical inner wall and a cylindrical punch, wherein the pressure of the clamping means is moderated in order that the metal matches the shape of the die during its deformation. It is applied in the production of can bodies from “double reduction” sheet metal.
EP-A-3702061 describes a method for producing a component from a metal sheet having an at least partially curved or linearly conical region made from a pot-shaped blank with a substantially cylindrical wall portion. The method is characterized in that it comprises at least the following steps:
a step drawing process, in which the cylindrical rim portion of the blank is formed, between a drawing die and a drawing punch movably guided in a fold holder, into a stepped region with two cylindrical portions; at least one subsequent cone drawing process, in which at least the stepped region is formed into the curved or linearly conical component portion between two tools.
EP-A-1372880 and EP-A-3691810 describe methods for producing rolled rims. In the case of EP-A-3691810, this is a method for producing a rolled edge from a cylindrical rim portion of a tube, in which an initial region of the rim portion is rolled by a positively controlled tool. Subsequently, a flanging tool passes into the rolled rim region and flanges the rolled rim region to form a roll. The method is characterized in that the initial region of the rim portion is folded over by the tool, which comprises a folding die and a counterholder, at an angle in the range of 75-105 degrees from the axial direction to form a substantially radially encircling flange.
An object of the present invention, inter alia, is to provide a method for producing an aerosol dome, which makes it possible, with as little material as possible (small material thickness), to produce a dome that is as stable as possible without damaging a lacquer coating or polymer coating located on the material.
Accordingly, a subject of the present invention is a method according to claim 1, and a use according to claim 14 and an aerosol dome according to claim 15.
Specifically, the present invention relates to a method for producing an aerosol dome having a dome region with an upwardly adjoining rolled rim arranged at an upper passage opening and with a downwardly adjoining flange region with an everted portion. Here, an intermediate stage is prepared in one or more stages from a lacquer-coated or polymer-coated blank, said intermediate stage having the upper passage opening, followed downwardly by a preferably substantially cylindrical neck portion, then followed by the dome region, which is followed by an encircling straight flange. This intermediate stage is processed in a processing stage in which only the everted portion is formed in a deep-drawing process.
Such a method is preferably also characterized in that the intermediate stage has an outwardly directed collar and/or, at the transition from the dome region to the neck region, an outwardly curved wave.
The processing stage for creating the everted portion is preferably followed directly or indirectly by at least one further stage in which a rolled rim is formed from the neck portion.
According to a further preferred embodiment, the processing stage for creating the everted portion is followed directly or indirectly by at least one further stage in which a preliminary stage or the final rim curl is created from the remaining flange, wherein preferably this further stage, if only a preliminary stage is formed, is 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. Preferably, no further steps then follow.
The lacquer-coated blank is preferably furnished in the form of a pot with an encircling flange, a rounded region and an end wall but without a neck region, and in at least one first stage, this blank is formed to the required part height H (typically in the range of 10-40 mm) prior to the creation of a rolled rim with an axial neck region, and preferably also in this first stage, the radius at the transitional region between the flange and the rounded region is reduced, preferably to a radius in the range of 0.2-1.0 mm, particularly preferably in the range of 0.3-0.6 mm.
After the first stage, in at least one, preferably in two further stages, a second stage and a third stage, the neck region can be formed further, in particular the radius of the region between the axial neck region and the radial end wall is reduced, preferably to a sharp edge with a radius in the range of 0.05-0.6 mm, particularly preferably in the range of 0.1-0.2 mm.
According to a further preferred embodiment, in at least one fifth stage, the end wall, which was optionally prepared with a score, is guided out of the tool as a dish, forming the upper passage opening, or is punched out, forming the upper passage opening, and preferably subsequently in a sixth stage, the encircling edge formed as a result is folded over to form a collar, wherein, furthermore, the fifth stage and the sixth stage are preferably carried out after the two further stages as set out above.
It is also preferred when, in one stage, preferably in the fifth stage according to the above description, an outwardly curved wave is formed in the dome region at the transition from the dome region to the neck region.
In one stage, preferably in the second stage and/or the third stage and/or the fourth stage, scoring can additionally carried out in the transitional region between the end wall and the neck region, in order to prepare the removal of the end wall.
A further preferred embodiment is characterized in that, to produce the rolled rim from a cylindrical rim portion of the neck portion, in a first step, preferably in the fifth step as set out above, an initial zone of the rim portion is folded over by a positively controlled tool to form the collar and in a second step, preferably in the further step as set out above, a flanging die subsequently passes into the folded-over rim portion and flanges the latter to form a roll, wherein, in the first step, the initial zone of the rim portion can be folded over by the tool, comprising a folding die and a counterholder, through an angle in the range of 75-105°, preferably in the range of 80-100°, or in the range of 85-95°, from the axial direction to form a substantially radial encircling flange.
The bending radius between the encircling flange and the adjoining axial portion is preferably smaller than twice the material thickness of the cylindrical rim portion, and preferably the bending radius lies in the range of 0.5-1.5 times, particularly preferably in the range of 0.75-1.25 times the material thickness of the cylindrical rim portion.
The radial length of the flange is also preferably in the range of 2-5 times, preferably in the range of 3-4 times the material thickness of the cylindrical rim portion.
The material of the blank is preferably provided with an impermeable lacquer coating on both sides or at least on the future top side (outer surface 7). The lacquer can be arranged directly on the metal, or via an additional adhesion promoting layer. The lacquer is preferably a polyester lacquer, an acrylate-based system or a methacrylate-based system or a polyurethane lacquer. Such a lacquer can be water-based or solvent-based, and it can be crosslinked. Preferably, the lacquer is applied without VOCs.
The blank can also be provided with an impermeable polymer coating or plastics coating, or with a plurality of such coatings. There are then usually additional adhesion promoting layers between the metal and the at least one plastics coating. The plastics coating can consist of polyethylene terephthalate (PET) or polypropylene (PP) or polyethylene (PE), or a mixture of such systems. The plastics coating can additionally have the usual additives (in particular plasticizers, fillers) and especially optionally dyes or pigments in the usual proportions.
The thickness of such a lacquer coating or plastics coating is typically in the range of 5-40 μm (including optionally present adhesion promoting layer).
The material thickness of the blank is typically in the range of 0.1-1 mm, preferably in the range of 0.15-0.4 mm, particularly preferably in the range of 0.18-0.34 mm.
The material of the blank is preferably sheet steel, preferably tinplate. Aluminium is also possible, however.
The material of the blank is preferably sheet steel
particularly preferably having a yield strength, determined according to DIN EN 10002-1:2001, of at least 500 MPa, preferably at least 520 MPa, particularly preferably at least 550 MPa,
and/or having a tensile strength, determined according to DIN EN 10002-1:2001, of at least 500 MPa, preferably of at least 550 MPa, particularly preferably at least 575 MPa.
Alternatively, the material of the blank is sheet steel, preferably tinplate of the 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, DR8.5, or DR9, each according to AISI/ASTM 623.
Furthermore, the present invention relates to the use of such a method to produce an aerosol dome for a spray can.
Furthermore, the present invention relates to a tool for carrying out such a method.
Finally, the present invention relates to an aerosol dome for a spray can producing using a method as set out above or in a tool as set out above.
Further embodiments of the invention are laid down in the dependent claims.
Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,
In order to produce a pot-shaped blank R from a thin, lacquer-coated material, a plurality of stages are passed through using the known methods.
One possible method is described in conjunction with
A pot-shaped blank R produced in a prior stamping and forming process is fed to the process as illustrated by the arrow 21. However, it is also possible for the production of this pot-shaped blank R, which is typically initially punched out of a raw material fed in the form of a strip and then deep-drawn to form a cup, this being able to take place in one or two steps, to be carried out as a first step in the scope of the sequence of stages described here.
This blank R, illustrated in a), has an encircling flange 15, which transitions via an initially cylindrical region 53 into a rounded region 17 and which has a closed end wall 18.
In the processing operation, illustrated by the arrow 22, in the first station S1, this blank R is subjected to first drawing Z1, wherein a punch is introduced 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 formed into a dome region 5, and a neck portion 14 is formed from parts of the rounded region 17 and the end wall 18, said neck portion 14 following the dome region via a transition 20. The end wall 18 obtains a smaller diameter, and a rounded portion 19 is established at the transition from the end wall 18 to the neck portion. The flange 15 substantially remains and the component does not yet have its final height, which is only established in subsequent steps.
In a step RP illustrated by the arrow 23, the rim is subsequently trimmed, i.e. the radial length of the flange 15 is set to the desired value; this step takes place in the context of the stations S2 and S3 (one of which is an empty station) and results in the component according to c).
In the processing operation, illustrated by the arrow 24, in the fourth station S4, this component is subjected to second drawing Z2, wherein again a punch is introduced 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 in height, and the neck portion 14 is lengthened and has its radius reduced.
In the processing operation, illustrated by the arrow 25, in the fifth station S5, this component is subjected to third drawing Z3, wherein once again a punch is introduced 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 round region 19 is shaped into a sharp edge 31 at the transition from the neck region 14 to the end wall 18.
In the processing operation, illustrated by the arrow 26, in the sixth station S6, this component is subjected to scoring Ri, i.e. an encircling score is created in the region of the transition 31 between the end wall 18 and the neck region 14, the function of said score during the further processing being as follows: The end wall is prepared in order to be torn away in the next station and to be drawn as a dish out of the tool. This results in the component illustrated in f).
In the crucial processing operation, illustrated by the arrow 27, in the seventh station S7, this component is subjected to several steps U at the same time. First, an everted portion 3 is created from parts of the dome region 5. This everted portion transitions via a vertical portion 9 into the flange 15 and radially inwardly into the dome region via an adjoining region 8. The material thickening (upsetting) that arises with this type of forming results in a significant load on the coating, and can result in flaking of the coating. On the other hand, with a smaller angle subsequently incorporated into a can, higher pressures can be withstood. At the same time, in this step, a slight outwardly directed wave 13 can be formed in the dome region 5, said wave adjoining the neck portion 14. Likewise at the same time, in this stage, the end wall, which was prepared in station 5, is guided as a dish out of the tool, resulting in a passage opening 32 at the top and a free straight edge 16 of the cylindrical portion 14, and the component height is set. This results in the component illustrated in g).
In the processing operation A, illustrated by the arrow 28, in the eighth station S8, this component is subjected to canting A. In other words, an initial zone of the rim portion 16 is folded over by a generally positively controlled tool and only then, as part of the next stage S9, in a second step, is a flanging die passed into the folded-over rim portion and flanges the latter to form a roll 2. In this step S8, the initial zone of the rim portion 16 is folded over by a tool, comprising a folding die and a counterholder, through an angle in the range of 75-105 degrees from the axial direction to form a substantially radial encircling flange 12. This results in the component illustrated in h).
In the processing operation W, illustrated by the arrow 29, in the ninth station S9, in this component the rolled rim 2 is formed and also the radial encircling edge of the flange 15 is folded over in a preliminary stage 11, such that a horizontal flange portion 10 remains. This results in the component illustrated in i).
Finally, in the processing operation RC, illustrated by the arrow 30, in the eleventh station S11, the final rim curl 4 is created.
In this sequence of stages for producing the aerosol cover, the flange 15 is everted. What is novel, however, is that this is intended to be deep-drawn using a material-friendly method.
In this method for producing the aerosol cover, the outer region of the dome region is everted to form the everted portion 3 and thus prepares the flange for the following station S9. This type of forming results in irregular lacquer damage on the cover, however.
Special attention is paid to the forming step in stage S7 after the scoring Ri during the eversion U, in which the part, in addition to the forming of the wave 13 and the removal of the cover, is subjected to a material displacement. In this case, the height of the part and the flange diameter required for beading is set. Since, in this case, the material has to be exposed in a particular region of the forming and is not held correctly, different tensile, compressive and bending stresses arise in the sheet metal, with the result that the lacquer can be damaged.
Using a novel forming step and a different sequence of stages, the lacquer damage is avoided. In this case, more material-friendly forming in the form of drawing is undertaken. First of all, the height of the part is set (see drawing Z1 and height setting in S1 in
A method according to the invention is illustrated in a sequence of stages in
A pot-shaped blank R produced in a prior punching and forming process is fed to the process as illustrated by the arrow 21. It is also possible for the production of this pot-shaped blank R, which is typically initially punched out of a raw material fed in the form of a strip and then deep-drawn to form a cup, this being able to take place in one or two steps, to be carried out as a first step in the scope of the sequence of stages described here.
This blank R, illustrated in a), has an encircling flange 15, which transitions via a transition 38 via an initially virtually cylindrical region 53 into a rounded region 17 and which has a closed end wall 18.
The material of the blank R is steel sheet, specifically tinplate, having a yield strength (determined according to EN 10202:2001, in particular Section 8.2, and the measurement method according to DIN EN 10002-1:2001) of at least 550 MPa. It has a tensile strength (determined according to EN 10202:2001, in particular Section 8.2, and the measurement method according to DIN EN 10002-1:2001) of at least 575 MPa. Typically, the material is tinplate of the 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, put another way of the type DR8, DR8.5 or DR9, each according to AISI/ASTM 623. The corresponding compositions and properties of these materials are defined in the stated standards.
The material is provided on both sides or at least on the future top side (outer surface 7) with a lacquer coating; a polyester lacquer was used here.
The blank can also be provided with a polymer coating or plastics coating, or with a plurality of such coatings. Possible, for example, is the commercial system Protect®.
In the processing operation, illustrated by the arrow 22, in the first station S1, this blank R is subjected to first drawing Z1 wherein a punch is introduced into the interior of the blank and the blank is pressed against a die (cf. also
In a processing operation, illustrated by the arrow 33, in the second station S2, this component is subjected to second drawing Z2, wherein again a punch is introduced into the interior and the component is pressed against a die. This results in the component illustrated in c). In this step, the dome region 5 is formed further, and the radius of the neck portion 14 is reduced.
In the processing operation, illustrated by the arrow 34, in the third station S3, this component is subjected to third drawing Z3, wherein once again a punch is introduced into the interior and the component is pressed against a die. This results in the component illustrated in d). In this step, substantially only the previously round region 19 is shaped into a sharp edge 31 at the transition from the neck region 14 to the end wall 18.
In the processing operation, illustrated by the arrow 26, in the fourth station S4, this component is subjected to scoring Ri, i.e. an encircling score is created in the region of the transition 31 between the end wall 18 and the neck 14, the function of said score during the further processing being as follows: The end wall is prepared in order to be torn away in the next station and to be drawn as a dish out of the tool. This results in the component illustrated in e).
In the processing operation BA, illustrated by the arrow 25, in the fifth station S5, the end wall 18, which was prepared in station 4, is guided as a dish out of the tool, punched out, and at the same time the wave 13 is formed in the dome region, specifically in the region that adjoins the neck region 14. This results in the component illustrated in f).
In the processing operation KA, illustrated by the arrow 28, in the sixth station S6, this component is subjected to canting A. In other words, an initial zone of the rim portion 16 is folded over by a generally positively controlled tool and only then, as part of a further stage S10, in a second step, is a flanging die passed into the folded-over rim portion and flanges the latter to form a roll 2. In this step S6, the initial zone of the rim portion 16 is folded over by a tool, comprising a folding die and a counterholder, through an angle in the range of 75-105 degrees from the axial direction to form a substantially radial encircling flange 12. This results in the component illustrated in g).
In the processing operation RB, illustrated by the arrow 35, the rim is subsequently trimmed, i.e. the radial length of the flange 15 is set to the desired value; this step takes place in the context of the stations S7 and S8 (one of which is an empty station) and results in the component according to h).
As far as its shaping is concerned, this component is now finished such that only the final steps need to be carried out on the flange 15 and the neck region 14, and in all the steps up to this point, the component can be guided optimally in each case. Thus, the eversion step in the next stage is carried out all alone and with a component in which all forming and punching operations have already been carried, inasmuch as they can be carried out before this step, without entailing problems with regard to process control. In particular, at this moment, the end wall 18 has already been punched out and the collar 12 formed, and the encircling wave 13 is likewise already present, and the final component height, apart from the rolling of the rolled rim 2, has been established.
In the crucial processing operation, illustrated by the arrow 54, in the ninth station S9, this component is now subjected to the step FZ. In this case, an everted portion 3 is created from parts of the dome region 5, and in this case it is possible to optimally hold and guide the material. This everted portion transitions via a vertical portion 9 into the flange 15 and radially inwardly in the adjoining region 8 into the dome region 5. This results in the component according to i).
In the processing operation W, illustrated by the arrow 29, in the tenth station S10, the rolled rim 2 is formed on this component, and also the radial encircling edge of the flange 15 is folded over in a preliminary stage 11 such that a horizontal flange portion 10 remains. This results in the component illustrated in k).
Finally, in the processing operation, illustrated by the arrow 30, in the eleventh station S11, the final rim curl 4 is created.
Separated from the effective sequence of stages, the stages S1 and S9 for forming the part of the flange are used here. A comparison with the sequence according to
Specifically, the height is thus initially set in combination with the first drawing. As a result, it is possible to work throughout with larger impression sleeves 43 and the damaging point at the radius is reduced or is no longer present at all. The part rests on the flange 15 which the impression sleeve is wider. The blank R is positioned by way of a downholder on the impression sleeve 43 via the fold holder 41, which is in a form fit with the blank R. Then, the material is drawn into the die and the first drawing process begins to develop. In the end position, the flange 15 is laid at the desired part height. Here, the radius Ra is also integrally formed immediately, and lies typically in the region of at least 0.30 mm.
As a result, the flange 15 is positioned and the material volume required for flange drawing is already at the correct location.
If the flange has been prepared for drawing, it is thus now only drawn into the die 49.
The part is controlled by the drawing die 46 via the impression sleeve 50 onto a spring-loaded, form-fitting receptacle 51. At the flange, a fold holder 48 prevents fold formation during forming.
Now the material at the flange 15 is drawn into the die. As a result, the flange height and the flange diameter are formed. Furthermore, the diameter for receiving the cover is formed in the body (can body) by the die.
During forming, the material is always enclosed and as a result does not have to succumb to an undesired or undefined material flow. This results in more material-friendly forming, with the result that lacquer damage caused by eversion is eradicated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21178792.4 | Jun 2021 | EP | regional |
