Method for producing high-dimensional half-shells and device for producing a half-shell

Abstract

Method for producing a high-dimensionally accurate half-shell from a cut-to-size blank, wherein the half-shell is pre-formed in a first die (28, 46) by deep drawing, optionally using at least one blank holder (56), wherein the first die (28, 46) has at least one punch (48), a die bottom (50), a die support surface (52) and a flange area, and wherein the pre-formed half-shell (30, 60) is subsequently final-formed in a second die (34, 62), in particular in a calibration tool, characterized in that - the circuit board is cut with a positive dimensional deviation within the specified tolerance range before deep drawing, taking into account the desired final shape of the pre-formed or finished half-shell, so that a final edge trimming of the half-shell can be omitted, - the die bottom (50) of the first die (28, 46) is moved relative to the die support surface (52), - the circuit board (24, 40, 57) is clamped between the die bottom (50) and the punch (48) of the first die (28, 46) and - the circuit board (24, 40, 57) is guided deep-drawn.

Description

[0001] The invention relates to a method for producing a highly dimensionally accurate half-shell from a cut blank, wherein the half-shell is pre-formed by deep drawing in a first die with optional use of at least one hold-down device, wherein the first die has at least one punch, a die bottom, a die support surface and a frame area, and wherein the pre-formed half-shell is subsequently finally formed in a second die, in particular in a calibration tool.

[0002] It is known from the state of the art to produce highly dimensionally accurate half shells by deep drawing a blank.

[0003] For example, it is known from DE 10 2007 059 251 A to produce highly dimensional accurate half-shells in a two-stage process. For this purpose, pre-formed half-shells are first produced which, due to their geometric shape, have excess material across their entire cross-section. The pre-formed half-shells are then compressed into their final shape through a further pressing process. A half-shell produced in this way has particularly high dimensional accuracy because the springback of the half-shell is superimposed by the introduced compression. A disadvantage of this manufacturing process, however, is that the pre-formed half-shells usually have to be subjected to further trimming to ensure they have the desired dimensions, particularly with regard to the frame height. To optimize the process chain, it is known from DE 10 2011 050 001 A1, for example, to integrate the final trimming into the deep-drawing process.According to this publication, to produce flangeless drawn parts, the flange area of ​​the half-shell is trimmed in the area of ​​the die support surface. The preformed half-shell thus produced is then calibrated in the same tool using an upsetting shoulder arranged on the drawing punch. However, this process still has the disadvantage that excess blank material is generated as waste and that the integration of the cutting edge into the deep-drawing die is subject to high tool wear. Furthermore, it cannot be sufficiently ensured that the blank does not change its position during deep-drawing, which subsequently creates dimensional inaccuracies in the preformed half-shell, which in turn necessitates trimming in the flange or frame area.

[0004] EP 2 125 263 B1 proposes, to optimize the efficiency of tempered forming of hot-rolled steel by deep drawing, to perform both the forming and the calibration of the component in a drawing die. To secure the blank during forming, it is clamped between the punch and the die base, which can be moved parallel to the direction of movement of the punch, and is deep-drawn while guided in the clamped state. Finally, the component is stamped by moving another upsetting shoulder towards it. This process also has the disadvantage that the tools for producing a deep-drawn part are complicated. DE 10 2008 037 612 A1 proposes forming a pre-formed half-shell into a final shape, wherein the pre-formed half-shell has excess material compared to the final-formed half-shell. The pre-formed half-shell is produced by conventional deep drawing.

[0005] Similarly, DE 10 2009 059 197 A1 discloses a method and device for producing a half-shell by deep drawing. WO 2005 / 105336 A1 also discloses a method and device for drawing-pressing a red-hot sheet metal blank, which, after the deep-drawing process, has an indentation in its base area. After drawing-pressing, the formed sheet metal blank is lifted from the die by an ejector.

[0006] US 2011 / 0165431 A1 relates to a method in which a blank is deep-drawn in a first die and calibrated in a second die, whereby a particularly small corner radius is achieved.

[0007] Based on the aforementioned prior art, the invention is based on the object of specifying a method and a device which simplifies the production of highly dimensionally stable half-shells.

[0008] According to a first teaching of the present invention, this object is achieved by the method mentioned at the outset in that the blank is cut to size with a positive dimensional deviation within the specified tolerance range prior to deep drawing, taking into account the desired final shape of the preformed or final-formed half-shell, the die base of the first die is moved relative to the die support surface, the blank is clamped between the die base and the punch of the first die, and the blank is deep-drawn in a guided manner. For example, the die base can be brought into line with the die support surface prior to deep drawing, so that the blank resting on the die support surface is clamped between the die base and the punch by further advancing the die base or by advancing the punch.Optionally, the blank can also be clamped beforehand between the at least one hold-down device and the die support surface so that the blank can be fixed in place so that it cannot slip, at least until the point at which the blank is clamped by the punch and the die base. Further optionally, the blank can be positioned in the desired position in the tool using suitable fixing and / or centering means until it is clamped by the punch and the die base. For optional clamping between the hold-down device and the die support surface, the die support surface can, for example, be moved in the direction of the hold-down device; however, it is also conceivable that the at least one hold-down device is moved in the direction of the die support surface and thus exerts pressure on the blank. In the subsequent deep-drawing process, the blank is deep-drawn in a guided manner according to the invention.For the purposes of the present invention, a guided deep-drawing process is understood to mean the deep-drawing of a blank, wherein the blank is clamped between the punch and the die base during deep-drawing. In other words, the die base exerts counterpressure on the blank during deep-drawing in relation to the force applied by the punch. The die base can therefore be subjected to a controllable force before and / or during deep-drawing. This has the advantage that the blank cannot slip uncontrollably during deep-drawing, but is positively and force-fittingly connected to the die base and the punch by the clamping. The blank is cut to size before deep-drawing with a positive dimensional deviation within the specified tolerance range, taking into account the desired final shape of the pre-formed or finally formed half-shell.By combining the use of such a cut blank with the guided deep-drawing process, a preformed half-shell can be produced that already provides edge and shape dimensional stability and, in particular, has a defined frame height and / or flange width, which can eliminate the need for final edge trimming of the half-shell. Overall, the process chain for producing a highly dimensionally stable half-shell can be shortened, and simple tools can be used. As a result, the method according to the invention can optimize and simplify the manufacturing process for a highly dimensionally stable half-shell. The method according to the invention can be used to produce half-shells with flanges as well as flangeless half-shells.

[0009] According to an advantageous embodiment of the method according to the invention, the die base of the first die is raised above the edge of the die support surface before deep drawing. This advantageously allows the blank to be clamped particularly easily between the punch and the die base. Furthermore, it can be prevented that the blank slips during clamping between the die base and the punch, for example, due to the pressure of the punch, or is deformed outside the area of ​​the die base.

[0010] Preferably, the blank is embossed by clamping in the area of ​​the die base, so that the blank takes on the shape of the die base. If the die base has a structure, for example in the form of a wave, this structure can be transferred to the blank by embossing. Due to the shape of the base, the preform has excess material, which can be advantageously used in the subsequent final forming. Optionally, the blank is also embossed before deep drawing by clamping it between the die support surface and at least one hold-down device. The frame area and optionally the flange area receive excess material that results from the shape of the blank or from the preform and the design of the tool.

[0011] According to a further preferred embodiment of the method according to the invention, the blank is positioned in a slip-proof and / or reproducible manner before and / or during deep-drawing using form-fitting and friction-locking means or fixing and / or centering means. For example, it is conceivable for the blank to be fixed in position before deep-drawing by limiters, guides, pins, magnets, or other form-fitting and / or friction-locking means. This fixing preferably takes place at least until the point in time at which the blank is clamped between the punch and the die base. By positioning and / or fixing the blank with repeatable accuracy before deep-drawing, it can be ensured that the deep-drawn blank has the desired final dimensions, in particular with regard to the frame height and / or flange width.During deep drawing, the blank is preferably fixed by the positive and force-locking connection with the die base and the punch, so that uncontrolled slipping of the blank during the deep drawing process can be avoided.

[0012] Furthermore, it is advantageous if the optional at least one blank holder exerts little or no force on the blank during deep drawing by adjusting its distance from the die support surface to at least equal to the actual thickness of the blank, thus largely preventing the blank from being stretched. By avoiding stretching of the blank in the frame area, it can be ensured that only minimal material fluctuations, for example, in the thickness of the frame area, are introduced into the dimensions of the preformed half-shell during the deep drawing process.

[0013] Particularly preferably, the vertical distance between the at least one hold-down device and the die support surface is set to the actual thickness of the blank, and the hold-down device exerts no or only a slight force on the blank during deep drawing, so that stretching of the blank is largely avoided. In this state, the at least one hold-down device limits the movement of the blank. For the purposes of the present invention, the actual thickness of the blank is understood to mean the actual thickness of the blank. For example, the actual blank thickness can be measured. In addition, it is also conceivable to reduce the distance between the at least one hold-down device and the die support surface until a counterpressure exerted by the blank acts on the hold-down device.In addition to the force exerted on the blank by the at least one hold-down device, it is advantageous if the friction of the blank on the die remains constant during deep drawing, particularly in the area of ​​the die support surface and in the frame area. This can be achieved, for example, by carrying out the deep drawing process at an essentially constant speed. Furthermore, the method is preferably always applied in the same orientation to the rolling direction of the blank. Since the behavior of the material during deep drawing depends on the rolling direction of the blank, dimensional inaccuracies of the pre-formed half-shell can be avoided by ensuring a consistent alignment of the rolling direction of the blank to the direction of deep drawing.

[0014] According to a particularly preferred embodiment of the method according to the invention, the blank is cut to size before deep drawing, taking into account the material flow during forming, such that edge and / or margin trimming is not required after forming. The blank cut is determined by reciprocally transferring positive dimensional deviations of the pre-formed or finally formed half-shell to the starting blank. Taking into account the flow laws of material flow, a blank contour can thus be determined which, after deep drawing, delivers a half-shell with consistent edges and shape dimensions, which does not require final edge and / or margin trimming or can be brought to the required size by upsetting. By additionally taking the material flow into account, the blank cut determined in this way can deviate from the cut defined in claim 1.By taking the material flow during deep drawing into account, holes from the preformed half-shell can also be made in the initial blank. As a result, no edge trimming of the half-shell and therefore no material waste is required, the manufacturing process for a highly dimensionally accurate half-shell can be simplified and efficiency increased.

[0015] Furthermore, a cutting edge can be arranged on the optionally at least one hold-down device and / or on the first die, by which the preformed half-shell is finally trimmed. Alternatively, the cutting edge can also be provided in the area of ​​the punch. Preferably, the half-shell is trimmed in the frame and / or flange area after deep drawing.

[0016] The preformed half-shell produced according to one of the previously described embodiments of the method according to the invention has a fully formed half-shell contour. If a flange area is provided, it has the intended width.

[0017] If no flange is provided, the flange material flows into the frame area at the end of the deep-drawing process and becomes part of it, so that the result is a half-shell with a defined frame height without a flange.

[0018] According to the invention, the preformed half-shell produced according to one of the previously described deep-drawing processes is finally formed in a second die. Within the context of the present invention, the final forming of the half-shell is understood to mean a calibration of the half-shell to achieve particularly high dimensional accuracy. The final forming process preferably accounts for between 10 and 20% of the entire process chain. It is particularly advantageous if the half-shell is transferred from the first die to the second die using dedicated means. Calibrating the half-shell can eliminate any remaining dimensional inaccuracies.

[0019] The preformed half-shell preferably has excess material, which is swaged in with a calibration punch during final forming in the second die. It is conceivable that the excess material is provided by introducing a structure, for example a wave, into the base region of the half-shell or, in the case of flanged parts, also in the flange region, preferably in all horizontal regions. The introduction of another structure, which results in the provision of excess material in the deep-drawn part, is also suitable for the present method. Alternatively or additionally, it is conceivable that the excess material is provided by introducing a corresponding structure in the frame region. Equally suitable is the provision of excess material by means of an extended frame and / or flange region of the preformed half-shell. This excess material is preferably swaged in during calibration.The applied compression compensates for the springback of the half-shell, successfully preventing springback of the material after the half-shell is removed from the second die. As a result, a particularly high dimensional accuracy of the manufactured half-shell is guaranteed.

[0020] It is conceivable that the inventive method could be carried out at room temperature during cold forming. However, it is also possible to carry out the inventive method during hot or semi-hot forming. For this purpose, the blank is heated to the forming temperature.

[0021] The method according to the invention is particularly suitable for the production of half-shells made of steel or a steel alloy. Therefore, in a preferred embodiment, the blank for producing the preformed half-shell is made of steel or a steel alloy.

[0022] The method according to the invention can be carried out using a device with at least one first die for producing a preformed half-shell, wherein the first die has at least one punch, a die base, a die support surface, and a frame region, and optionally at least one hold-down device is provided. The die base of this device is displaceable relative to the die support surface so that the blank can be clamped between the punch and the die base. Advantageously, the die base can be raised above the plane of the die support surface so that the blank can be clamped between the die base and the punch particularly easily. Furthermore, it is advantageous if the blank can be clamped between the punch and the die base in such a way that it is simultaneously stamped and thus assumes the shape of the die base.In this way, a structure, for example, for providing a material supply, can be introduced into the bottom area of ​​the half-shell. Furthermore, the blank can be deep-drawn in a guided manner while clamped. For this purpose, the device is preferably arranged in a press.

[0023] According to a preferred embodiment of the die, the die support surface and the optional at least one hold-down device are arranged so as to be displaceable relative to one another. A blank located on the die support surface can be clamped in the area of ​​the die support surface by moving the at least one hold-down device and / or the die support surface closer to it, for example, to fix its position. Preferably, the blank can be clamped in such a way that it is simultaneously stamped and assumes the shape of the die support surface.

[0024] Furthermore, it is preferred if form-locking and / or frictional locking means or fixing and / or centering means are provided, by which a blank can be positioned securely and / or reproducibly before and / or during deep-drawing. For example, limiters, guides, pins, magnets, or other form-locking and / or frictional locking means can be provided. Preferably, the blank is held securely in position during deep-drawing by being clamped between the punch and the die base. The precise and reproducible positional fixation of the blank ensures the dimensional accuracy of the preformed half-shell.

[0025] According to a further embodiment of the device, a cutting edge can be arranged on the optionally at least one hold-down device and / or on the first die, or alternatively in the area of ​​the punch, by means of which the preformed half-shell can be finally trimmed. This advantageously allows the frame height and / or the flange width of the preformed half-shell to be influenced even after the deep-drawing process.

[0026] It is also advantageous if the die base and / or flange area, or the horizontal areas in the deep-drawing tool, have a shape suitable for providing excess material for the preformed half-shell. If the blank is clamped between the punch and the die base in such a way that it is simultaneously stamped and thus takes on the shape of the die base, the structure for providing excess material can be particularly easily incorporated into the base of the half-shell. A wave shape, for example, is suitable. However, other structures are also conceivable.

[0027] According to a further preferred embodiment of the device, at least one second die is provided for final shaping and / or calibration of the preformed half-shell, which optionally has means for transferring the half-shell from the first die to the second die.

[0028] The invention will be explained in more detail below using exemplary embodiments in conjunction with the drawing. The drawing shows Fig. 1 a method for producing a highly dimensionally stable flangeless half-shell according to the prior art in a schematic representation, Fig. 2 a first embodiment of the method according to the invention for producing a flangeless half-shell in a schematic representation, Fig. 3a-d a first embodiment of the procedure for determining the blank size, Fig. 4a-c show a first embodiment of the deep-drawing process according to the invention for producing a preformed half-shell and a first embodiment of a first die of the device for carrying out the method according to the invention and in, Fig. 5 a first embodiment of the final forming according to the invention and a first embodiment of a second die of the device for carrying out the method according to the invention.

[0029] Fig. 1 shows a method for producing a highly dimensional-accurate half-shell according to the prior art. In a first step 2, a blank 4 is deep-drawn in a first die 6. After the deep-drawing process 2, the half-shell 8 produced in this way has protrusions 10 that reduce the dimensional accuracy of the pre-formed half-shell 8. In a next step 12, these protrusions 10 are removed by trimming the half-shell 8. This can either be done in a further die or be integrated into the first deep-drawing process 2. After the final trimming 12, the frame area of ​​the flangeless half-shell 14 has the desired target height. Due to the deep-drawing process 2, the half-shell 14 has a dimensional inaccuracy that can be eliminated in a subsequent final forming step 16 using a calibration tool 18. As a result, a highly dimensional half-shell 20 can be produced in this way.However, this method has the disadvantage that the trimming 12 lengthens the process chain for producing a highly dimensionally accurate half-shell 20, and if the trimming is integrated into the deep-drawing process, complex tooling is required for the manufacturing process. Furthermore, material waste is generated, which reduces the efficiency of the manufacturing process.

[0030] Fig. Figure 2 shows a first exemplary embodiment of the method according to the invention for producing a flangeless half-shell. In a first step, the blank 24 in the present exemplary embodiment is cut to size, taking into account the desired final shape of the preformed or finally formed half-shell, prior to deep-drawing with a positive dimensional deviation within the specified tolerance range, such that edge and / or border trimming is no longer necessary during the manufacturing process. This trimming, however, is optional. The cut blank is deep-drawn in a second step 26 guided through a first die 28. Regarding the explanation of the guided deep-drawing process, reference is made to the description of Fig. 4b. After the deep-drawing process 26, the preformed half-shell 30 has defined dimensions, particularly with regard to the frame height. In the subsequent final forming step 32, the preformed half-shell 30 is calibrated in a second die 34. It is particularly advantageous if the preformed half-shell 30 is transferred into the second die 34 by a transfer means. Using the method according to the invention, a highly dimensionally accurate half-shell 36 can be produced particularly easily and efficiently.

[0031] The Fig. 3a to d show a first embodiment of the procedure for determining the blank size before deep drawing. In a first Fig. In the step shown in Figure 3a, a deep-drawn half-shell 38 is simulated from a round blank 40, taking the material flow into account. The simulation shows that the deep-drawn half-shell 38 has unwanted lobes 42. Starting from the simulated deep-drawn half-shell 38, the areas of the unwanted regions 42 are determined, as shown in Fig. 3b. In the next step, the areas of the unwanted regions 42 are transferred to the output board 40 by a back calculation, which ultimately determines the area of ​​the regions 42 to be removed. Fig. 3c shows the initial blank 40 and the area 42 to be removed. A blank 44 corrected in this way can be deep-drawn into a flangeless half-shell 45, which has defined dimensions, in particular with regard to the frame height. Fig. 3d shows a simulation of a half-shell 45 deep-drawn from the cut blank 44.

[0032] In the Fig. 4a to c show a first embodiment of the deep-drawing process according to the invention for producing a preformed half-shell and a first embodiment of a first die of the device according to the invention. Fig. 4a shows a first die 46 with a punch 48, a die base 50, a die support surface 52 and a frame area 54, a hold-down device 56, and a cut blank 57. Furthermore, the die 46 has guides 58, which, on the one hand, hold the hold-down device 56 at a distance from the die support surface 52 that corresponds at least to the blank thickness and, on the other hand, prevent the blank 57 from slipping on the die support surface 52. The guides 58 allow the blank 57 to be positioned in the die 46 in a slip-proof and reproducible manner.

[0033] The die base 50 is movable relative to the die support surface 52. In the Fig. In the position shown in Figure 4a, the die base 50 is raised above the edge of the die support surface 52. Furthermore, the punch 48 is lowered so far that the blank 57 is clamped between the punch 48 and the die base 50. The die base 50 has a shape suitable for providing excess material for the preformed half-shell. For this purpose, the die base 50 has the shape of a wave. In the illustrated embodiment, the blank 57 is clamped between the punch 48 and the die base 50 in such a way that it is simultaneously embossed and thus assumes the shape of the die base 50. The structure of the die base can thus be transferred to the base region of the preformed half-shell, so that the half-shell has excess material in the base region, which can be advantageously utilized during final forming.

[0034] Fig. Figure 4b shows the guided deep-drawing process of blank 57. The illustration shows that blank 57 is deep-drawn in a clamped state. Consequently, during deep-drawing, blank 57 experiences not only the pressure from punch 48 but also counterpressure from die base 50. Advantageously, the distance of hold-down device 56 is adjusted to the blank thickness during deep-drawing. This largely prevents stretching of blank 57 during deep-drawing. During the deep-drawing process to produce a flangeless half-shell, the flange area of ​​blank 57 also flows into the frame.

[0035] Fig. Figure 4c shows the deep drawing process at bottom dead center. The blank 57 is completely formed into a half-shell 60. The Fig. Half-shell 60, shown in Figure 4c, has excess material both in its structured base area and in an extended frame area. Due to the lack of ironing during deep drawing, the resulting half-shell 60 springs back upon removal from the die 46.

[0036] Therefore, the preformed half-shell 60, as in Fig. 5, calibrated in a second die 62, preferably with a calibration punch 64. In the illustrated embodiment, the excess material of the preformed half-shell 60 is compressed, resulting in a highly dimensionally accurate half-shell that exhibits no springback effects upon removal from the calibration die 62.

Claims

[1] Method for producing a highly dimensionally accurate half-shell from a cut blank, wherein the half-shell is pre-formed by deep drawing in a first die (28, 46) with optional use of at least one hold-down device (56), wherein the first die (28, 46) has at least one punch (48), a die base (50), a die support surface (52) and a frame area, and wherein the pre-formed half-shell (30, 60) is then finally formed in a second die (34, 62), in particular in a calibration tool, characterized by , that - the blank is cut to size before deep drawing, taking into account the desired final shape of the preformed or final formed half-shell, with a positive dimensional deviation within the specified tolerance range, so that a final edge trimming of the half-shell can be omitted, - the die base (50) of the first die (28, 46) is moved relative to the die support surface (52), - the blank (24, 40, 57) is clamped between the die base (50) and the punch (48) of the first die (28, 46) and - the plate (24, 40, 57) is deep-drawn in a guided manner. [2] Method according to claim 1, characterized by that the die base (50) of the first die (28, 46) is raised above the edge of the die support surface (52) before deep drawing. [3] Method according to claim 1 or 2, characterized by that the plate (24, 40, 57) is embossed by the clamping in the area of ​​the die base (50). [4] Method according to one of claims 1 to 3, characterized by that the blank (24, 40, 57) is positioned in a slip-proof and / or reproducible manner before and / or during deep drawing using form-locking and / or frictional locking means or fixing and / or centering means. [5] Method according to one of claims 1 to 4, characterized bythat the vertical distance between the at least one blank holder and the die support surface is adjusted to the actual thickness of the blank and that the blank holder exerts no or only a small force on the blank during deep drawing, so that stretching of the blank is avoided as far as possible. [6] Method according to one of claims 1 to 5, characterized by that the blank (24, 40, 57) is cut to size before deep drawing, taking into account the material flow during forming, in such a way that edge and / or margin trimming is not required after forming. [7] Method according to one of claims 1 to 6, characterized by that the preformed half-shell (30, 60) has excess material which is compressed with a calibration punch during the final forming in the second die (34, 62).

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