EP2248926A1 - Method for producing a stamped part - Google Patents

Abstract

The method for producing a shaped part (1) from an aluminum sheet (2) comprising aluminum alloy of the 5000 series, comprises introducing the aluminum sheet in a forming tool, cold-forming the aluminum sheet, heating the cold-formed aluminum sheet once in some regions, and then subjecting the heated aluminum sheet to a further formation step yet before reaching a temperature which has the aluminum sheet during its cold-forming. The aluminum sheet is formed into a partial form of the shaped part by cold forming and into the final form of the shaped part by the further formation. The method for producing a shaped part (1) from an aluminum sheet (2) comprising aluminum alloy of the 5000 series, comprises introducing the aluminum sheet in a forming tool, cold-forming the aluminum sheet, heating the cold-formed aluminum sheet once in some regions, and then subjecting the heated aluminum sheet to a further formation step yet before reaching a temperature which has the aluminum sheet during its cold-forming. The aluminum sheet is formed into a partial form of the shaped part by cold forming and into the final form of the shaped part by the further formation. The cold-formed aluminum sheet is heated at 150-350[deg] C below a recrystallization temperature of the aluminum sheet. Before cold-forming, the aluminum sheet is provided with a temperature -resistant lubricant, which is removed from the aluminum sheet in a step after the further formation step. The aluminum sheet is introduced into the forming tool during the further formation step, and is partially formed by deep-drawing. For heating the cold-formed aluminum sheet, the aluminum sheet is partially introduced into a counter mold of a heating tool following the form of the aluminum sheet. The cold-formed aluminum sheet is partially cut before and/or after the further formation step.

Description

The invention relates to a method for producing a molded part from an aluminum sheet having an aluminum alloy, in particular from an aluminum alloy of the 5000 series, in which at least the aluminum sheet is introduced into a forming tool and cold formed by this and in a further step or in further steps the cold-formed aluminum sheet is heated at least once at least in some areas and at least once further formed.

In order to achieve a high degree of deformation with a comparatively high strength of a molded part, it is known from the prior art ( DE 10 2008 032 911 A1 ), an aluminum sheet first cold forming at room temperature, then a warming or a heat aging and finally again subjected to cold forming at room temperature. In particular, cold work hardening resulting from cold forming should be reduced by hot aging in order to be able to guarantee an increased degree of deformation. A disadvantage of this known method is its comparatively long process time, because in particular the hot aging with its heating and subsequent cooling is time-consuming. Fast turnaround times or a flexible adaptation in the number of production of molded parts can not be made possible with such a method. On top of that, a hot aging in a furnace comparatively costly and also calls for a large amount of space, so that thus a cost-effective production of moldings can not be performed.

The invention is therefore based on the object to improve a method of the type described in such a way that, despite a high strength of the molding a fast turnaround time in the production of the molding and a flexibly customizable production output of moldings can be made possible. In addition, this method should provide a cost-effective production of moldings.

The invention solves this problem by the fact that the heated aluminum sheet is subjected to further forming before reaching a temperature which has the aluminum sheet during its cold forming.

If the heated aluminum sheet is subjected to further shaping before reaching a temperature which the aluminum sheet has during its cold forming, then not only can the time interval between the two forming steps be reduced, so that comparatively short throughput times can be achieved, but it can also prove that this does not significantly reduce the strength of the molding compared to other processes. Namely, the heating can be used advantageously or can certainly be used for the recovery of the microstructure of the aluminum alloy in order to be able to counteract unwanted strain hardening. This is readily possible for a person skilled in the art via the parameters of time and / or temperature level during heating and possibly also over the time of a subsequent cooling. The parameters during heating and thereby not excluded cooling of the aluminum sheet can certainly be chosen or adjusted so that, for example, before cooling the heated and cold-formed aluminum sheet to room temperature, the aluminum sheet can be subjected to further forming. However, this does not exclude that several times heating and / or cooling of the aluminum sheet until further Reshaping is carried out, it can only be crucial that the heated aluminum sheet is subjected to further forming before reaching a temperature which has the aluminum sheet during its cold forming. According to the invention, a method can now be provided which can combine the advantages of a short throughput time on the one side, which are contrary to the prior art, with a comparatively high degree of deformation and a comparatively high strength on the other side. It is further conceivable to increase the degree of deformation that the cold-formed and further heated in a further step aluminum sheet is fed directly to further forming without substantial cooling and then the aluminum sheet is subjected to a warm forging below the recrystallization or hot deformation above the recrystallization temperature of the aluminum alloy. In any case, a method can be created with the avoidance of thermal aging, with which a comparatively continuous processing of the aluminum sheet can take place. Such methods are also referred to as "in-line" method, since in these from the first step to the finished molding no significant storage times must be met. For this reason, the inventive method in the production of a molded part with an aluminum alloy on relatively large production areas, which must exist for example by a storage during artificial aging, can be dispensed with, so that thus a cost-effective production can be possible. In addition, it may be that an oven for a cold aging can be avoided, which does not require a significant number of cold-formed aluminum sheets must be made so that a flexibly adaptable production output can be possible by the inventive method. It should also be noted that an aluminum sheet can be understood as a flat finished rolling mill made of an aluminum material or aluminum alloy.

If the aluminum sheet is formed by the cold forming into a partial shape of the molded part and by the further forming in the final shape of the molded part, then increased deformation of the molded part can open, because the aluminum sheet can be exposed to increased stresses by a heated further forming. In addition, or alternatively, can be started during cold forming with a reduced deformation of the aluminum sheet into a part mold, so that even with a reduced risk of the formation of work hardening must be expected. In particular, the degree of deformation during cold forming can be set such that the heating carried out in a next step and, if appropriate, cooling is sufficient to reduce such strain hardening in the microstructure that no substantial change in strength must be expected.

An advantageous recovery of the structure after the cold forming may result if the cold-formed aluminum sheet is heated below the recrystallization temperature of the aluminum alloy, in particular between 150 and 350 degrees Celsius.

If the aluminum sheet is provided with a temperature-resistant lubricant before cold-forming, then the method according to the invention can allow the aluminum sheet to be removed from the lubricant only in one step after further forming. The applied lubricant can thus remain on the aluminum sheet during the process, because its disintegration can be avoided by avoiding a thermal aging known from the prior art. Costly and time-consuming cleaning steps are reduced so advantageous because only in one step after further forming the lubricant is removed from the aluminum sheet. Lubricants or lubricants with a temperature resistance up to 350 degrees Celsius are known from the prior art.

Advantageous properties for the production of the molded part result when the aluminum sheet is at least partially reshaped by deep drawing. Likewise, this can be applied to a combination of deep drawing and ironing to reshape the aluminum sheet.

If the aluminum sheet is introduced during further forming in a forming tool, then advantageous process conditions for the production of the molded part can be created. It may also be possible to reuse the forming tool already used in cold forming, which may save costs. If the forming tool is heated, then a possible cooling of the aluminum sheet can be reduced.

If the cold-formed aluminum sheet is at least partially trimmed before and / or after further forming, then a special accuracy of the molded part thus created can be made possible.

Fig. 1

ein Besprühen eines Aluminiumblechs mit Schmiermittel,

Fig. 2

einen Schritt des Kaltumformens des Aluminiumblechs mit einem Umformwerkzeug,

Fig. 3

ein Beschneiden des kaltumgeformten Aluminiumblechs mit einem weiteren Werkzeug,

Fig. 4a und 4b

alternative Möglichkeiten zum Erwärmen des kaltumgeformten Aluminiumblechs,

Fig. 5

ein weiteres Umformen des erwärmten Aluminiumblechs in einem Umformwerkzeug,

Fig. 6

ein abschließendes Endbeschneiden des Aluminiumblechs mit einem Werkzeug und

Fig. 7

das durch das Verfahren hergestellte Formteil.

In the figures, for example, a flow example of the method according to the subject invention is shown. Show it

Fig. 1

spraying an aluminum sheet with lubricant,

Fig. 2

a step of cold working the aluminum sheet with a forming tool,

Fig. 3

trimming the cold-formed aluminum sheet with another tool,

Fig. 4a and 4b

alternative possibilities for heating the cold-formed aluminum sheet,

Fig. 5

a further forming of the heated aluminum sheet in a forming tool,

Fig. 6

a final end trimming of the aluminum sheet with a tool and

Fig. 7

the molding produced by the process.

According to the FIGS. 1 to 6 For example, the inventive method for producing a molded part 1 after Fig. 7 described in more detail. So is according to Fig. 1 to recognize that an aluminum sheet 2 having an aluminum alloy, for example, the 5000, 6000 or 7000 series, after Fig. 2 a change in shape in particular deformation is subjected. In particular, the 5000 series has been found to be preferred because this alloy comparatively solid, formable and easier to process further. The aluminum sheet 2 is introduced for the purpose of forming in the forming tool 3 and is cold-formed therein at room temperature, in particular deep-drawn. Thereafter, the cold-formed aluminum sheet 2 is removed from the forming tool 3 and a according to Fig. 4a heated gas burner 4 shown schematically. Other ways of heating the aluminum sheet 2 are conceivable and familiar to a person skilled in the art, for example, this can be done via waffle irons, infrared, laser, induction, ultrasound and / or via conductive methods. In general, the cold-formed aluminum sheet 2 can thus be heated in whole or in part, in the latter case this can be in or in the surrounding area of the areas of the aluminum sheet 2 which are the most stressed by the forming. Temperatures in the range of 150 to 350 degrees Celsius are conceivable, but the heating should be below the recrystallization temperature of the aluminum alloy. In a further step after Fig. 5 Now, the aluminum sheet 2 is subjected to a further deformation with a forming tool 5, said forming tool 5 also optionally the forming tool 3 after Fig. 2 can represent. Again, the aluminum sheet 2 is deep-drawn by means of the forming tool 5. To create special conditions in the production of the molding 1, the aluminum sheet 2 in this further transformation Fig. 5 at least partially an elevated temperature relative to the temperature during cold working. This can be achieved in that even before cooling the heated cold-formed aluminum sheet 2 to its temperature during the cold forming after Fig. 2 the aluminum sheet 2 of the further transformation Fig. 5 is subjected. It can therefore be created an "in-line" process in manufacturing, because the well-known from the prior art artificial aging can not interrupt the inventive method. So can react faster to customer requirements in the number of units, which among other things, a complex storage support can avoid. In addition, the method according to the invention also makes it possible to provide a device with a reduced space requirement, because, for example, the comparatively large space requirement for hot aging can be avoided.

To the degree of work hardening during the first forming of the aluminum sheet 2 after Fig. 2 To reduce the aluminum sheet 2 is first brought into a partial mold 6 of the molded part 1 during cold forming. Then it is then by further reshaping Fig. 5 the aluminum sheet 2 and the partial mold 6 are brought into the final shape 7 of the molded part 1. The after FIGS. 2 and 5 different deformation can be detected, for example, at the different in height left parts of the molds 3 and 5. Sohin can the FIGS. 2 and 4 can be taken that the aluminum sheet 2 is increased during further forming compared to cold forming increased, so as to obtain reduced cold work hardening during cold forming. However, the degree of deformation in the two steps for forming can also be reversed or the same, which has not been shown in detail.

Before the cold forming of the aluminum sheet 2, this is provided with a temperature-resistant lubricant 8. For this representation of the method step is in Fig. 1 a spray nozzle 9 is shown, via which the lubricant 8 can be applied to the aluminum sheet 2. Since the method according to the invention can avoid long process steps, such as those caused by artificial aging, and in contrast to the aluminum sheet 2 is formed into a molded part 1 in comparatively short time intervals, the lubricant 8 can on the assumption of a temperature resistance to the last step on the Aluminum sheet 2 remain without a decomposition of the lubricant 8 must be feared. Elaborate cleaning processes or a repeated application of lubricant 8 can be avoided. In contrast to the prior art is thus conceivable that lubricant 8 from the aluminum sheet 2 only in one step after further forming after Fig. 5 to remove, for example, in the step after Fig. 7 can be done.

A particularly uniform and / or positionally accurate heating of the cold-formed aluminum sheet 2 can take place if this in the form of the aluminum sheet 2 at least partially following counter-forms 10, 11 of a heating tool 12 is introduced, which heating tool 12 in Fig. 4b is shown. Along the contour of the countershapes 10, 11 heating means 13 are provided at the locations of the desired heating.

After cold forming after Fig. 2 the cold-formed aluminum sheet 2 is introduced into a tool 14 in order to be able to trim it at least to partial dimensions. This tool 14 may already be provided with means for heating the cold-formed aluminum sheet 2, which has not been shown in detail. This could, however, the process step after Fig. 4a or 4b be avoided.

After further reshaping Fig. 5 the final form 7 can be further trimmed, including in Fig. 6 this is introduced into a tool 15. This tool 15 can also the tool 14 after Fig. 3 represent. Likewise, in this process step Fig. 6 or in further process steps, not shown, the final shape 7 can be shortened and / or possibly also punched.

Claims (8)

Method for producing a molded part (1) from an aluminum sheet (2) comprising an aluminum alloy, in particular from an aluminum alloy of the 5000 series, in which at least the aluminum sheet (2) is introduced into a forming tool (3) and cold-worked therethrough, and in another Step or in further steps, the cold-formed aluminum sheet (2) at least once at least partially heated and at least once further formed, characterized in that the heated aluminum sheet (2) before reaching a temperature, the aluminum sheet (2) during its cold forming has, which is subjected to further forming. A method according to claim 1, characterized in that the aluminum sheet (2) by the cold forming into a part mold (6) of the molded part (1) and by further forming in the final shape (7) of the molded part (1) is formed. A method according to claim 1 or 2, characterized in that the cold-formed aluminum sheet (2) below the recrystallization temperature of the aluminum alloy, in particular between 150 and 350 degrees Celsius, is heated. A method according to claim 1, 2 or 3, characterized in that prior to the cold forming the aluminum sheet (2) is provided with a temperature-resistant lubricant (8), wherein only in one step after further forming the lubricant (8) from the aluminum sheet (2) Will get removed. Method according to one of claims 1 to 4, characterized in that the aluminum sheet (2) during further forming in a, in particular heated forming tool (5) is introduced. Method according to one of claims 1 to 5, characterized in that the aluminum sheet (2) is formed by deep drawing at least partially. Method according to one of claims 1 to 6, characterized in that for heating the cold-formed aluminum sheet (2) of this in a form of the aluminum sheet at least partially following counter-mold (10, 11) of a heating tool (12) is introduced. Method according to one of claims 1 to 7, characterized in that the cold-formed aluminum sheet (2) is trimmed before and / or after further forming at least partially.

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