Patent Application
20250058368
The invention relates to a method and a device for manufacturing sheet metal components.
Methods and devices for manufacturing dimensionally stable sheet metal components are disclosed in the prior art, see for example DE 10 2007 059 251 A1, DE 10 2008 037 612 A1, DE 10 2009 059 197 A1, DE 10 2013 103 612 A1, DE 10 2013 103 751 A1, whereby the manufacture is carried out in at least two stages (forming processes). In the first stage, a blank, in particular a flat blank, is formed into a preform. The preform has an excess of material that is as evenly distributed as possible compared to the final sheet metal component geometry to be produced. In the second stage, known as calibrating, this excess material is compressed, particularly in the direction of the sheet metal plane. The inhomogeneous stress state of the preform is realigned and the undesirable, batch-dependent springback of the sheet metal component, which occurs in particular with high-strength materials in combination with low sheet thicknesses, is largely avoided.
Further prior art is disclosed in the publications US 2016/0361747 A1 and DE 10 2016 118 419 A1.
When calibrating sheet metal components with a (weld) flange, lateral sliders are usually moved to the calibration punch via wedge drivers when the calibration tool is closed and remain there during the calibration process. The edge of the preform flange rests on the slider during calibration, whereby the compressive stress overlay is realized by compressing the excess material. The contact between the preform and the slider is only in the area of the edge of the preform flange. There is still no satisfactory concept for sheet metal components with sections or significant areas without a (weld) flange. The previous concepts envisage creating a preform that essentially corresponds to the final geometry, whereby the effective surfaces of the preform tool are essentially based on the effective surfaces of the calibration tool.
The invention is thus based on the task of providing a generic method and a generic device with which dimensionally stable sheet metal parts can be produced which are flangeless at least in sections.
This problem is solved by a generic method with the features of patent claim 1.
This task is solved by a generic device with the features of claim 8.
According to the teaching of the method according to the invention, it is provided that the method for producing a sheet metal component comprises at least two steps: preforming a sheet metal into a sheet metal preform in a preforming tool, wherein the sheet metal preform has at least one flangeless section in its longitudinal extension and excess sheet metal material at least in some regions; and final forming of the sheet metal preform into a sheet metal component in a calibrating tool comprising at least one calibrating punch and at least one calibrating die, in which the excess sheet metal material in the sheet metal preform is compressed by relative movement between the calibrating punch and the calibrating die, wherein, during the final forming process, an edge of the sheet metal preform, which is present at least in the flangeless section, comes into contact with a slider shoulder having an essentially horizontally movable slider, is supported thereon and is subjected to a pressure in order, in particular, to be compressed.
It has been established that dimensionally accurate sheet metal components can be produced which are flangeless at least in sections and can be calibrated or finish-formed in particular with a frame opening angle of equal to or greater than 0°, in particular greater than 2°, preferably greater than 4°, preferably greater than 6° with an extended but simplified calibrating tool setup using sliders. When upsetting or calibrating by means of compressive stress superimposition, at least the edge of the sheet metal preform present in the flangeless section can be supported on the slider shoulder of the slider, which can be moved essentially horizontally to the calibrating die. It is important to ensure that the sheet metal preform does not become trapped between the calibrating punch and calibrating die during the calibrating process when the calibrating tool is closed, which would result in damage to the finished sheet metal component and/or the calibrating tool.
The frame opening angle is the maximum angle by which the sheet metal component frame can be rotated inwards in relation to the direction of action of the calibrating tool (press ram) around an axis oriented in the longitudinal direction of the sheet metal component in the transition area between the frame and the sheet metal component base before an undercut occurs in the tool.
By sliders that can be moved essentially horizontally to the calibrating die, it should be understood that in addition to a feed of 0°, an angled feed of up to +/−45°, in particular up to +/−30°, preferably up to +/−15° to the horizontal can also be permitted.
Viewed in cross-section, the sheet metal preform and the final sheet metal component have at least one bottom and at least two protruding frames, each with a transition between the bottom and the two frames. Furthermore, depending on the design of both the sheet metal preform and the final sheet metal component, there is at least one flangeless section in the longitudinal direction. This means that either local sections can be flangeless on one or both sides or one side can be completely flangeless and/or optionally the other side can only be partially flangeless. In particular, the sheet metal preform as well as the final sheet metal component can be designed without flanges. For example, a flange can be attached to one of the frames and at least in sections, whereby the sheet metal preform and the final sheet metal component can thus have a transition between the frame and the flange at least in sections. Preferably, the final sheet metal component can have sections with and without a flange. The flangeless section can therefore also be understood as being only on one side of the sheet metal preform, although the sheet metal preform can also have no flange on either side, at least locally when viewed in cross-section, depending on the design.
The sheet metal preform can be produced in one or more steps using any combination of shaping processes. The preforming can, for example, include a deep-drawing-like shaping step. In particular, shaping can also take place in more stages, for example by embossing the bottom to be produced and raising the frames to be produced or setting down the flanges to be produced. Any combination of folding and/or bending and/or (embossing) is also conceivable. The deep-drawing-like shaping carried out for preforming, for example, can be carried out in one or more stages. Preferably, forming can be carried out without active material flow control to produce the sheet metal preform. Depending on the design, the preforming tool must then be designed accordingly.
Final forming of the sheet metal preform is understood to mean upsetting/calibrating, which can be achieved by one or more pressing processes, for example. Excess sheet material is provided in the sheet metal preform produced, at least in some areas. In the sheet metal preform, the excess sheet material has a cross-sectional unwound length that is between 0.5% and 6% longer in relation to the unwound length of the finished sheet metal component (target geometry), at least in some regions. The unwound length of the cross-sections of the sheet metal preform considered in this way is in particular between 0.7% and 4.3% longer than that of the finished sheet metal component. If, as a result of the process control during the production of the sheet metal preform, the unwound length of the cross-sections varies too much, there would not be enough excess sheet material available for the subsequent final forming if the unwound length is too short, which would impair the dimensional accuracy of the final sheet metal component. If, on the other hand, the unwound length of the considered cross-section of the sheet metal preform is too long, the oversized sheet material would collapse into waves during the subsequent final forming process, which could result in a visual and/or dimensional defect. In addition, there would be an increased risk of tool damage due to excessive compression forces or protruding, crushed sheet metal component areas, such as sheet metal edges.
The essentially fully formed sheet metal component can therefore be understood as the final formed sheet metal component. However, it is possible that the fully formed sheet metal component can be subjected to further processing steps that modify the sheet metal component, such as the insertion of connection holes, the placement of welding flanges, the insertion of local embossing and/or a small final trim and/or the performance of secondary forming steps such as the insertion of additional, local embossing or, for example, the placement of flanges on the ends of the sheet metal component.
The sheet metal preform produced and the finished sheet metal component essentially have a longitudinal extension and a transverse extension, whereby in most sheet metal components the longitudinal extension is larger than the transverse extension in terms of dimensions. Thus, cross-section means a section through the transverse extension of the sheet metal preform/component.
According to one embodiment of the method according to the invention, the sheet metal preform is inserted into the calibrating tool in such a way that its opening points downwards and is positioned on the calibrating punch. The advantage of inserting the sheet metal preform produced as a quasi “open” profile with the opening facing downwards is that it is easier and simpler to position the sheet metal preform. In particular, the calibrating punch is stationary and the calibrating die is movable in the calibrating tool. Furthermore, the slider arranged at least in the flangeless section of the sheet metal preform can also be designed to be movable on one or both sides in relation to the calibrating punch, depending on the design of the sheet metal component to be formed. There is no need to turn the sheet metal component before any further downstream operations, such as trimming and/or punching operations, as the trimming/hole waste, for example, can simply be discharged downwards.
Since the upsetting/calibrating force generated during the final forming process is directed into the slider via the edge of the sheet metal preform, which is present at least in the flangeless section, too large a gap in the area of the frame would lead to damage to the sheet metal component and thus to high wear or damage to the calibrating tool. Thus, according to a further embodiment of the method according to the invention, it is provided that the slider is moved in the direction of the calibrating punch during the relative movement between the calibrating die and the calibrating punch to such an extent that a defined distance between the slider and the calibration punch is selected, at least in the area of the flangeless section of the sheet metal preform, which corresponds to the material thickness of the sheet metal used plus >0 to 0.35 mm, in particular 0.01 to 0.20 mm, preferably 0.02 to 0.10 mm. As a result, the edge of the sheet metal preform is surrounded on all sides by stable tool surfaces, particularly before the start of the final forming process, before the edge of the sheet metal preform is supported on the slide shoulder of the slide during the final forming process and the final sheet metal component geometry is produced in the actual calibrating process.
According to one embodiment of the method according to the invention, the sheet metal preform is provided with a bottom, which is loaded with excess sheet material during the preforming process, at least in the flangeless section, in such a way that a bottom region bulging in the direction of the opening has been produced during the preforming process, so that the sheet metal preform is positioned on the calibrating punch at least via the pre-curved bottom area at least in the area of the flangeless section of the sheet metal preform in such a way that the edge of the sheet metal preform present at least in the flangeless section is arranged above the slider shoulder. The base of the preform, at least in the flangeless section, can have an excess sheet material that is distributed as evenly as possible in the base (area), which, for example, has been subjected to 0.5 to 6% material addition (ratio of unwound length of sheet metal preform ↔ sheet metal component) during the production of the sheet metal preform in order to realize a compressive stress superimposition during final forming in the calibrating tool, preferably in such a way that the pre-curved base area is positioned on the calibrating punch before the start of the actual finish forming in such a way that the frame(s) of the sheet metal preform is/are positioned above the slider shoulder during the closing of the calibration tool, thus reliably preventing the edge in particular between the slider, calibrating die and calibrating punch from being pinched.
According to an alternative or additional embodiment of the method according to the invention, the sheet metal preform is provided with a bottom in which local or sectional embossments pointing in the direction of the opening have been produced during preforming, so that the sheet metal preform is positioned at least via the embossments on the calibrating punch in such a way that the edge of the sheet metal preform present at least in the flangeless section is arranged above the slider shoulder. The embossing introduced into the bottom of the preform locally or in sections during preforming can be distributed longitudinally along the bottom or can also be introduced only as local or sectional embossing at the two ends of the sheet metal preform when viewed longitudinally. In this way, compressive stress superimposition can be realized during the final forming in the calibrating tool by positioning the sheet metal preform on the calibrating punch via the embossments in the bottom before the actual final forming begins in such a way that the frame(s) of the sheet metal preform is positioned above the slider shoulder during the closing of the calibrating tool, thus reliably preventing jamming between the calibrating die and the calibrating punch.
According to a further alternative or additional embodiment of the method according to the invention, the sheet metal preform is provided with a bottom, at least a partial region of the bottom coming into contact with at least one adjustable insert arranged in the calibrating punch when the sheet metal preform is inserted into the calibrating tool, which is spaced apart from the calibrating punch when the sheet metal preform is inserted into the calibration tool, and the sheet metal preform is positioned on the insert at least via the partial region of the base at least in the region of the flangeless section of the sheet metal preform in such a way that the edge of the sheet metal preform present at least in the flangeless section is arranged above the slider shoulder. The insert or several inserts in the calibrating punch arranged at least in the flangeless section can be spring-loaded or driven, for example by a wedge driver, hydraulically, pneumatically, electromechanically or electromagnetically, and can additionally or alternatively be used to realize a compressive stress superimposition in the calibrating tool during final forming, preferably in such a way, that the sheet metal preform is positioned on the calibrating punch before the start of the actual final forming process in such a way that the frame(s) of the sheet metal preform is/are securely positioned above the slider shoulder during the closing of the calibrating tool, thus reliably preventing the edge in particular between the slider, calibrating die and calibrating punch from being pinched.
According to one embodiment of the method according to the invention, the slider is controlled in such a way that it assumes an end position which is set between 10 and 80 mm before the bottom dead center of the calibrating tool is reached. In other words, the end position of the slider(s) is thus reached before the start of the final forming process, so that the edge of the sheet metal preform is surrounded on all sides by stable tool surfaces before the edge of the sheet metal preform is supported on the slider shoulder of the slider during the final forming process and the final sheet metal component geometry is produced. In particular, the end position of the slider is set between 20 and 60 mm, preferably between 30 and 50 mm, before the bottom dead center of the calibrating tool is reached.
The task mentioned at the beginning is solved in a generic device with at least one preforming tool for preforming a sheet metal into a sheet metal preform, wherein the sheet metal preform has at least one flangeless section in its longitudinal extension and excess sheet metal material at least in some regions; and with at least one calibrating tool for final forming of the sheet metal preform into a sheet metal component, wherein the calibrating tool comprises at least one calibrating punch, at least one calibrating die and at least one substantially horizontally movable slide, wherein the excess sheet material in the sheet metal preform is compressed by the relative movement between the calibrating punch and the calibrating die, wherein the slider has a slider shoulder which is provided at least in the flangeless section of the sheet metal preform, so that by relative movement the edge of the sheet metal preform present at least in the flangeless section can be brought into contact with the slider shoulder of the slider, can be supported thereon and can be subjected to a pressure.
Preferably, a final sheet metal component is produced with a profile that is open at the bottom in the calibrating tool (press position), so that the calibrating punch is arranged at the bottom and the calibrating die at the top in the calibrating tool and can be moved relative to each other. The calibrating punch is preferably mounted on a press table and the calibrating die on a press ram of the calibrating tool designed as a press. Furthermore, at least one slide that can be moved horizontally to the calibrating ram is/are also arranged on the press table. Depending on the design of the sheet metal component to be produced, with flangeless sections and at least one section with a flange, corresponding calibrating tool elements adapted to the flange section are provided in sections at least in the area of the flange, on one or both sides, in order to realize a pressure stress superposition also in the at least partial flange section.
Preferably, the calibrating tool is segmented accordingly in order to finish forming flangeless and flanged sections on a sheet metal preform into a sheet metal component.
In order to avoid repetition, reference is made to the explanations of the method according to the invention.
According to one embodiment of the device, the slider shoulder is designed as a projection of the slider (male section) and the calibrating punch has a recess on one or both sides (female section), at least in the flangeless section of the sheet metal preform, in which the projection of the slider can be accommodated during the final forming of the sheet metal preform.
As much of the calibrating die as possible is designed in one piece. This ensures that only a small proportion of the forces acting laterally during the calibrating process act on the sliders. A slight additional opening of the calibrating die and/or the sliders and thus of the calibrating gap can lead to increased waviness of the frames of the finished calibrated sheet metal component. A calibrating die should therefore be as rigid as possible. Calibrating die halves designed entirely as moving parts would require large, very stable driver units and thus lead to increased tool costs and increased dimensions of the calibrating tool. According to one embodiment of the device, the slide or slides are therefore designed in particular in such a way that they preferably cover less than 50% of a lateral height of the sheet metal component to be manufactured, particularly preferably less than 30% of a lateral height of the sheet metal component to be manufactured.
According to one embodiment of the device, the slider has at least one projection (male section) or several projections and/or at least one recess (female section) or several recesses at least in the flangeless section of the sheet metal preform on its upper side facing the calibrating die, and the calibrating die also has at least one projection (male section) or several projections and/or at least one recess (female section) or several recesses at least in the flangeless section of the sheet metal preform on its underside facing the slider, so that when the sheet metal preform is fully formed and thus when the calibrating tool is closed, the projection on the underside of the calibrating die can be accommodated in the recess on the upper side of the slider and, conversely, the projection on the upper side of the slider can be accommodated in the recess on the underside of the calibrating die. The projection/recess principle can be designed in sections or completely along the longitudinal extension of the calibrating tool on one or both sides. The projection/recess principle achieves a kind of “interlocking” so that when the calibrating process starts shortly before bottom dead center, the frame is largely supported laterally. This further reduces the risk of the sheet metal preform buckling into the gap between the die and slide during calibrating.
According to one embodiment of the device, the calibrating punch has at least one adjustable insert arranged in the calibrating punch, which can be moved away from the calibrating punch. In particular, the at least one insert is movable relative to the calibrating punch. The element(s) arranged in the calibrating punch is (are) driven, for example, via the plunger stroke and/or additional control units, for example by means of springs, wedge drivers, hydraulics or pneumatics. The element can be used to set a defined distance between the element and the calibrating punch, which can be used to set a distance between the edges provided in the flangeless section in particular and the slide shoulder of the slide. During the final forming or closing of the calibrating tool, the element is retracted completely flush into the calibrating punch.
According to one embodiment of the device, the slider is drive mechanically, hydraulically, pneumatically, electromagnetically or by other suitable means and/or can be fixed in an end position during the final forming of the sheet metal preform. The end position corresponds to the closed position of the slider during the final forming or closing of the calibrating tool.
According to a further embodiment of the device, the slider can be controlled in such a way that it assumes an end position which can be set between 10 and 80 mm before the bottom dead center of the calibrating tool is reached. In particular, the end position of the slider can be set between 20 and 60 mm, preferably between 30 and 50 mm, before the bottom dead center of the calibrating tool is reached.
According to one embodiment of the device, the slider ledge can be designed perpendicular to the frame or inclined at an angle of +/−30° to the vertical of the frame. This allows a sheet edge to be produced, particularly in the flangeless section, which is oriented perpendicular to the local frame of the finished sheet metal component.
According to one embodiment of the device, the device is integrated into a press line or transfer press. Particularly in the manufacture of mass products, for example for products in the automotive industry, products such as sheet metal components are manufactured particularly economically in press lines or transfer presses. The device according to the invention can be used economically in existing production lines in the form of interchangeable inserts, which provide at least one preforming tool and at least one calibrating tool. It is also conceivable to use the device according to the invention in downstream compound presses.
The invention is explained in more detail below with reference to the drawings. Identical parts are provided with identical reference signs. In detail:
a sequence of steps at different times for manufacturing a sheet metal component according to one embodiment of the method according to the invention and a device according to the invention in a schematic sectional view,
The sheet metal preform (2) or the sheet metal component (3) can, for example, comprise at least one flanged section (L), shown here on the left-hand side of the downwardly open profile, and at least one flangeless section (2.1). If there is at least one section in the longitudinal extent (L) with a flange, which can for example be arranged on one side or both sides in different sections, there is also a transition between the frame and the flange in the area of the flange. The following explanations are based on an example that shows a section in cross-section in which both sides of the sheet metal preform (2) and, as a result, both sides of the sheet metal component are flangeless in at least one section. Of course, only one side can also be flangeless and the other side can be flanged in cross-section or completely flangeless (not shown).
The sheet metal preform (2) is created in such a way that excess sheet metal material (4) is provided, which is preferably arranged in the bottom and/or in the bottom and in the transition between the bottom and the frame(s) and/or in the frames, preferably evenly distributed in the sheet metal preform (2). Excess sheet material can be introduced into the sheet metal preform (2) in the bottom as a bottom area (2.2) that is pre-curved in the direction of the opening (Ö) of the sheet metal preform (2) in order to make the sheet metal preform (2) at least over the pre-curved bottom area (2.2) at least in the region of the flangeless section (2.1) of the sheet metal preform (2) on the calibrating punch (21) in such a way that the edge (2.11) of the sheet metal preform (2) present at least in the flangeless section (2.1) is arranged above the slider shoulder (23.1) of the slider (23). Alternatively or additionally, at least one adjustable insert (21.2) can be arranged in the calibrating punch (21), which can be spaced apart from the calibrating punch (21), so that at least a partial area of the bottom comes into contact with the insert (21.2) and the sheet metal preform (2) is positioned on the insert (21.2) at least via the partial region of the bottom at least in the region of the flangeless section (2.1) of the sheet metal preform (2) in such a way that the edge (2.11) of the sheet metal preform (2) present at least in the flangeless section (2.1) is arranged above the slider shoulder (23.1) of the slider (23). This ensures that the slider(s) (23) can be moved into their end position in the direction of the calibrating punch (21) without negatively influencing the edge (2.11), see
According to an alternative or additional embossments (2.3) pointing locally or in sections in the direction of the opening (Ö), see right-hand representation of the sheet metal preform (2) in
The final forming of the sheet metal preform (2) into a sheet metal component (3) takes place in a calibrating tool (20) comprising at least one calibrating punch (21), at least one calibrating die (22) and at least one slide (23) which can be moved essentially horizontally, for example essentially horizontally to the calibrating punch (21), in which the excess sheet material (4) in the sheet metal preform (2) is compressed by relative movement between the calibrating punch (21) and the calibrating die (22). It has been found to be advantageous that during the final forming process, the edge (2.11) of the sheet metal preform (2) present at least in the flangeless section (2.1) comes into contact with a slide shoulder (23.1) provided on a slide (23) which can be moved essentially horizontally, is supported thereon and is subjected to a pressure in order to be compressed in particular.
The slide or slides (23) move in the direction of the calibrating punch (21) after the sheet metal preform (2) has been positioned on the calibrating punch. The slider (23) comprises a projection (23.2), at least in the flangeless section (2.1) of the sheet metal preform (2), which extends in the direction of the calibrating punch (21) and has the slider shoulder (23.1) on the upper section. The calibrating punch (21) comprises a recess (21.1) on one or both sides at least in the flangeless section (2.1) of the sheet metal preform (2), in which the projection (23.2) of the slider (23) can be accommodated during the final forming of the sheet metal preform (2). The projection (23.2) thus plunges into the recess (21.1), see
The embodiment according to the invention can ensure that the sheet metal preform (2) can be positioned on the calibrating punch (21) without jamming before final forming or before closing the calibrating tool (20) and that flangeless sections (2.1) can also be final formed in a dimensionally accurate manner alongside flanged sections in a sheet metal component (3). For the final forming of the flanged sections, further sliders, in particular those not shown, are provided for blocking the flange edges of the sheet metal preform in the calibrating tool, so that these sections can also undergo compressive stress superimposition in the same way as the flangeless sections (2.1).
The invention is not limited to the designs shown. Other sheet metal part shapes are also possible and require correspondingly adapted tool contours. In particular, the tools (10, 20) can be designed as interchangeable tools and can be used in a production line, in particular in a press line, transfer press or progressive press.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2022 100 163.6 | Jan 2022 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/086052 | 12/15/2022 | WO |
