Patent Application
20140047887
This application claims priority under 35 USC §119 to German Patent Application No. 10 201 2 201815.8 filed on Feb. 7, 2012, which application is hereby incorporated by reference.
The invention relates to a device and a method for surface treatment of cylindrical elements through draw wall ironing.
A process designated as draw wall ironing produces a cylindrical element for example in the production of beverage cans from a bowl that is generally produced from sheet metal through deep drawing, wherein the bowl essentially has the dimensions of the final product to be produced besides still requiring trimming and necking.
Draw wall ironing reduces a wall thickness and the exterior dimension of the bowl to form the cylindrical element. For process reasons the draw wall ironing is performed “wet” which is different from impact extruding and uses a cooling- and lubricating agent.
During conventional processing a trimming of the free sheet metal edge and a complex cleaning and drying of the produced cylindrical element is performed subsequent to draw wall ironing.
Thus, it is an object of the present invention to provide a device and a method for surface treatment of cylindrical elements in the context of draw wall ironing, wherein the device facilitates at least one additional variant of surface treatment without additional complexity.
In order to achieve the element a device for surface treatment of cylindrical elements with a surface treatment in several process steps is proposed including a first cleaning device for removing residuals of a coolant and lubricant used for draw wall ironing from a cylindrical element produced through draw wall ironing so that a cleaned and pre dried cylindrical element is provided, a surface treatment device for treating at least one surface of the cleaned and pre dried cylindrical element and a second cleaning device for cleaning the surface treated cylindrical element.
Typically a surface treatment method like for example brushing is being avoided if possible in known production methods which use draw wall ironing since such processing generates a sludge from the released material and the cooling and lubricating agents, which sludge is only removable with great difficulty and which necessitates an immediate and complex cleaning of the processing machines since otherwise a failure of the machines would have to be expected soon thereafter. A surface treatment like for example brushing could also be performed after complete cleaning and drying of the cylindrical element essentially at an end of the conventional process before optional painting, wherein renewed cleaning would be possible before painting or similar finishing.
The invention provides the advantage that it avoids the complex cleaning that was customary so far with little additional complexity or at least substantially reduces the associated complexity.
A method for surface treatment of cylindrical elements is also proposed, including the following steps: providing a cylindrical element that is produced through draw wall ironing, removing the residuals of a cooling- and lubricating agent used for draw wall ironing from the cylindrical element, so that a cleaned and pre-dried cylindrical element is provided, treating at least one surface of the cleaned and pre-dried cylindrical element and cleaning the surface treated cylindrical element.
Additionally a computer program is proposed that includes computer program devices which cause a computer to control a device according to the invention to execute the method according to the invention when the computer program is executed on the computer.
The invention is based on the finding that it is sufficient for avoiding or reducing the problems recited supra to combine a partial cleaning (in the sense of a non-final cleaning) with a subsequent rudimentary drying process in order to provide a desired surface treatment. It can be stated that the surface treatment with preceding limited drying is inserted between a first and a second portion of a known two step washing method. However, it is appreciated that the first and the second cleaning device are not limited to only performing respective partial steps of a conventional washing process. It is possible that processes which are performed by the first and the second cleaning device overlap with one another, thus particular method steps are performed twice.
The invention requires an additional drying device in a practical application in addition to the surface treatment device compared to a conventional process, wherein the additional drying device, however, only has to comply with reduced requirements and overall requires more installation space. The advantages associated with avoiding or at least reducing the problems recited supra, however, justify this comparatively small increase in complexity.
In order to simplify the language, the instant application recites a cooling- and lubrication agent in conjunction with draw wall ironing. It is appreciated that this initially does not have to be a homogenous or single substance agent since a mix of different agents (i.e. liquids) can be used. The term “cooling and lubrication agent” furthermore does not have to be interpreted in every case in a limited manner so that the agent is simultaneously used for cooling and lubrication purposes. The term “cooling and lubrication agent” eventually stands for the means which are used for supporting or simplifying the process of draw wall ironing or a process like deep drawing a bowl as an intermediary product which may be performed before the draw wall ironing.
In this application the term “cylindrical element” initially designates a beaker shaped element with a base and a sidewall, wherein the cross-section is circular. The application, however, is not limited to such configuration. It is also possible in the context of the present invention that the cylindrical element is either initially produced without a base or that the base is removed during the process. Deviations from the circular cross-section of the wall are not excluded as a matter of principle either. It is furthermore appreciated that the base does not have to be flat and can have some shaping.
In an advantageous embodiment, the surface processing device is configured for roughening or optically matting the at least one surface, preferably for brushing the at least one surface.
The use of brushing for surface treatment is known for example in a context with cans generated through flow pressing, wherein an occurrence of abrasion in a context with “wet” draw wall ironing and the “sludge” associated therewith thus made brushing after draw wall ironing unattractive for process technology reasons so far. In the context of the present invention, however, brushing can be used largely circumventing a sludge formation after draw wall ironing.
Thus, the present invention is not limited to brushing. For example a laser treatment or a plasma treatment can also be used as alternative and/or supplemental methods.
In an advantageous embodiment the device furthermore includes an abrasion removal device for preferably dry removal of abrasion that has been generated during surface processing from the cylindrical element, in particular through an air flow or an air blast before cleaning the surface treated cylindrical element.
Due to the pre drying performed before the surface treatment, the abrasion generated during processing also remains in a dry state which facilitates a simple removal, for example through air impact. It is appreciated that the removal can also be performed using another gas or gas mix.
In an advantageous embodiment, the first cleaning device includes a pre-washing unit for removing residuals of the cooling- and lubrication agent and a drying device for drying the cylindrical element which has been cleaned from the cooling and lubricating agent.
For example when the cooling and lubricating agent includes light soaps and oils, these can be removed with a respectively adapted pre-washing unit, wherein a drying comes after this removal. The agents used for pre-washing can be preferably removed in a simpler manner from the surface for drying than this would be the case for the cooling- and lubricating agents themselves.
In an advantageous embodiment, the pre-washing unit is configured for etching the cylindrical element, in particular through acid treatment and/or a base treatment.
The “washing” of the cylindrical elements known from the conventional method sometimes includes etching with an acid and/or a base, wherein for example an acid treatment can be performed by the pre-washing unit.
It is furthermore possible in the first and second cleaning device to provide different treatments, for example a treatment with an acid and a treatment with a base in different cleaning devices in order to better separate the different treatments from one another.
In an advantageous embodiment the drying device is configured for drying at least the surface provided for surface treatment up to a first degree of drying, preferably up to a second degree of drying, wherein no additional droplets form at least at the surface provided for surface treatment and wherein the second degree of drying is characterized in that no humidity is sucked into a downstream vacuum system.
A complete drying of the surface that is typically provided for preparing a lacquering or coating is not required for preparing the surface treatment. It has been found that generally already a first degree of drying is sufficient for significantly reducing the problems initially stated wherein no drops are formed anymore at the cylindrical element. A stronger drying could mean for example for a second degree of drying that also in a hypothetical subsequent vacuum system no wetness or only insignificant wetness is sucked in. A third degree of drying represents a level of dryness in which removed particles, thus abrasion do not adhere to one another anymore due to van-der-Waals-forces.
In the practical implementation a balance adapted to particular conditions can be found between the desired or required degree of dryness and a simpler abrasion removal associated therewith and the complexity to achieve this degree of drying.
In an advantageous embodiment, the drying unit includes an oven and/or a blower for drying.
The drying unit can thus provide drying through a combination of an air- or gas-flow and an oven impact (e.g. convection, radiation and/or induction) or also only singular means.
In an advantageous embodiment, the cylindrical element is a one-piece element that is closed at its base and made from aluminum or an aluminum alloy.
Even though the invention is not limited to a cylindrical element with a base made from aluminum or an aluminum alloy, this constellation represents a preferred implementation.
Alternatively it is however also possible for example to provide a cylindrical element made from steel sheet metal or tin plated steel sheet metal, in particular to provide a surface treatment through laser and/or plasma processing. A brushing of tin plated steel sheet metal may only be performed up to a depth in which it remains assured that the tin is not removed from the surface.
In an advantageous embodiment the second cleaning device is configured for washing and drying the surface treated cylindrical element, in particular for washing and drying to prepare a further processing of the cylindrical element.
Through dividing the cleaning steps in a first and second cleaning device, it is possible to pull the cleaning steps ahead which are required or desired for preparing the surface treatment, wherein the remaining or eventually additional cleaning- or drying steps are provided in a final step in the second cleaning device.
In an advantageous embodiment the second cleaning device is configured for a base treatment of the cylindrical element.
As stated supra providing the first and the second cleaning device can be used to better separate different treatments from one another (e.g. acid treatment in the first cleaning device and base treatment in the second cleaning device). This way a protraction of employed agents that can occur in a conventional cleaning device can be avoided even better.
In an advantageous embodiment the device further includes a trimming device for trimming the cylindrical element, wherein the trimming device is in particular configured for trimming the pre-dried cylindrical element before surface treatment.
The trimming device for desired trimming of the cylindrical element can be provided at different stages in the process, wherein preferably the trimming is performed before the surface treatment.
In an advantageous embodiment, the device includes plural first cleaning devices and/or plural surface treatment devices and/or plural second cleaning devices which are respectively arranged for parallel operations.
The particular process steps in the different elements of the device can use different times per cylindrical element, wherein an optimum loading of the entire process chain is achievable through respective operation of plural elements parallel to one another.
In an advantageous embodiment, the device includes a draw wall ironing device for producing a cylindrical element.
The invention can be used for a separate pre-fabrication and supplying of cylindrical elements and also in a context where the cylindrical elements are produced directly before further processing them on site. This applies for producing a bowl, for example by deep drawing from a piece of sheet metal which precedes the draw wall ironing process.
The invention is subsequently described based on embodiments with reference to appended drawing figures, wherein:
The draw wall ironing device 20 is configured to receive a blank also designated as bowl and to form a cylindrical element from the blank through draw wall ironing. The cylindrical element thus formed (sometimes also designated “pre form”) is supplied by the draw wall ironing device 20 to the first cleaning device 30.
The first cleaning device 30 includes a pre-washing unit 32 and a drying unit 34. Through the pre-washing unit residuals of cooling- and lubricating agent which was used during draw wall ironing are removed from the supplied cylindrical element, wherein this removing also includes a treatment with an acid. The cylindrical element thus sufficiently cleaned from cooling- and lubricating agent is then dried by the drying unit 34 which includes an oven and a blower (not illustrated) until a desired degree of drying is achieved in which no more drops form at the dried cylindrical element. After running through the first drying unit 30, thus a cleaned and pre-dried cylindrical element is provided which is provided to the trimming unit 40.
The trimming unit 40 is used to trim the cylindrical element to a desired dimension, wherein the trimming assures in particular that dimensional deviations generated through the draw wall ironing with respect to the height of the cylindrical element are removed. From the trimming device 40 the trimmed cylindrical element is provided to the surface processing unit 50.
Through the surface treatment device 50, a treatment in the form of brushing at least one of the surfaces of the cylindrical element is provided so that the cylindrical element has a roughened and/or optically more matt surface on the treated surface.
The abrasion particles released when brushing with the surface treatment device 50 are removed by the abrasion removal device 60 in a dry manner using an air flow, wherein the cylindrical element thus cleaned from abrasion is subsequently provided to the second cleaning device 70.
The second cleaning device 70, similar to the first cleaning device 30 includes a washing unit 72 and a drying unit 74. Differently from the first cleaning device 30, however, the second cleaning device 70 is provided for a final and complete cleaning of the cylindrical element, wherein in particular the drying unit 74 provides a molecular drying of the cylindrical element so that the eventually cleaned and dried cylindrical element can be coated and/or lacquered (not illustrated).
In the embodiment illustrated in
Some process steps or devices which are designated as sequential in the embodiment, as this is the case during surface treatment in the surface treatment device 50 and abrasion removal in the abrasion removal device 60, can also be performed in parallel or can be combined in a device quite well. In a combined surface treatment and abrasion removal device, the abrasion released during surface treatment would also be removed simultaneously.
It is furthermore possible that different devices of the device according to the invention jointly perform particular functions. Thus, for example abrasion removal can be performed up to a certain degree through the abrasion removal device 60, wherein the remaining residual abrasion is removed by the second cleaning device 70.
The device 10 may include computer 80 in one or more of its associated devices and units 20, 30, 32, 34, 40, 50, 60, 70, 72 and 74 or as a separate computer, including a memory 82 stored with instructions, which when executed by the computer, performs the method shown in
10 device
20 draw wall ironing device
30 first cleaning device
32 pre-washing unit
34 drying unit
40 trimming device
50 surface treatment device
60 abrasion removal device
70 second cleaning device
72 washing unit
74 drying unit
80 computer
82 memory
110 providing
120 removing
130 treating
140 cleaning
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2012 201 815.8 | Feb 2012 | DE | national |
