DE102012021032A1 - Device for inductive heating of metallic workpiece e.g. aluminum sheet, has sleeve element that is made of ferromagnetic material and provided to encompass induction coil - Google Patents

Abstract

The device (1) has an inductor (5) comprising an induction coil (7). The induction coil is positioned to face the workpiece. A sleeve element (9) is made of ferromagnetic material and provided to encompass the induction coil. The sleeve element is provided with a supporting surface (17) whose geometry is formed complementary to the contour region of the workpiece. The inductor is displaceable relative to the workpiece. An independent claim is included for a method for heating metallic workpiece.

Description

The invention relates to a device for inductive heating of metallic workpieces, in particular sheets or stampings, according to the preamble of claim 1, a forming device according to the preamble of claim 6, and a method for heating metallic workpieces, in particular of sheets or stampings, according to claim 7.

Devices and methods of the type discussed here are known. From the DE 10 2008 032 911 A1 is a method for forming an aluminum sheet forth, which is partially formed in a first step at room temperature to a certain degree of deformation. Subsequently, the workpiece is stored warm in an intermediate cooling process. Thereafter, it is formed into a final molding in a second cold forming process. In this case, the hot aging step preferably takes place in a paging furnace. It is also known to inductively heat metallic workpieces and in particular metal sheets for forming by arranging and energizing at least one inductor having an induction coil in a region of the workpiece to be heated. This produces an electromagnetic alternating field which induces eddy currents in the region of the workpiece to be heated, the region to be heated being heated by eddy current losses. In ferromagnetic materials occur in addition to core losses, so that they can be inductively heated particularly efficient.

A disadvantage of an inductive heating of a workpiece is that it can deform, in particular bulge, in the heated area. It is hardly or at least only possible to a limited extent to support the workpiece by the inductor itself, because this should not have direct contact with the workpiece if possible.

Therefore, if a deformation or bulging of a workpiece is to be avoided, so-called direct contact tools are typically used, which are preheated and then brought into thermal contact with the workpiece. This is energy consuming and complicated, especially because a complex cooling of the workpiece in areas is necessary, which must not be heated.

From the not previously published German patent application DE 10 2012 003 667.1 is a recording device with a coil assembly for inductive heating of a component to be formed, in which the coil assembly is embedded in a molded body made of a solid. The solid is formed as a resin, plastic, ceramic or the like. By the molding a long-term stable, technically meaningful coupling distance between the coil assembly and the component to be formed is ensured. The solid from which the shaped body consists is designed as an electrical insulator in order not to bridge the windings of the coil arrangement.

The invention has for its object to provide an apparatus, a forming device and a method which provide an improved way to maintain the shape of a heated workpiece, in particular a sheet or a stamping in the heated area.

The object is achieved by providing a device having the features of claim 1.

The fact that the induction coil, at least on a side facing a workpiece to be heated, has a covering element enclosing it, which comprises a ferromagnetic material, makes it possible to support the metallic workpiece to be heated in the region to be heated, the jacket element being in direct contact with can stand the workpiece. Unlike conventional direct contact heating, when using the device, it is not necessary to preheat it, thereby allowing a very energy efficient and rapid heating of the workpiece. In contrast to a direct contact tool, the contact of the jacket element with the workpiece is preferably formed locally, so that it is sufficient if only the relatively small area of the jacket element has a high surface quality for tight contact with the workpiece. This allows a cost savings compared to known direct contact tools, because a lower complexity of the tool is required. With the help of the inductor and the jacket element, it is therefore also possible to specifically heat the area of the workpiece to be heated locally, so that a complex and complex cooling of areas not to be heated is eliminated.

The term "inductive heating" here includes in particular the possibility that at least substantially only the ferromagnetic material of the sheath element is heated inductively, while the metallic workpiece at least substantially by thermal contact with the sheath element and / or emitted by the sheath element heat radiation and optionally heated by convection.

The term "inductor" here refers to the metallic workpiece facing part of Device which causes its heating, wherein the inductor comprises the induction coil and at least one supply line and at least one derivation for the electrical current to the coil or from the coil.

A device is preferred which is characterized in that the jacket element consists of a ferromagnetic material. In particular, the jacket element is preferably formed homogeneously from the ferromagnetic material. It preferably comprises or consists of steel.

Also preferred is a device in which the jacket element is mounted as a hood on the induction coil. In this case, the jacket element preferably comprises a bottom element facing the workpiece, which overlaps the coil at least partially, preferably completely on the side facing the workpiece, wherein it preferably additionally has a circumferential edge or collar, which is seen in the circumferential direction of the induction coil, which surrounds the induction coil engages laterally. Thus, the induction coil is preferably both covered and encompassed by the jacket element. Preferably, the jacket element is held on the induction coil itself or otherwise on the inductor. However, it is also preferred an embodiment in which the jacket element is attached to at least one other part of the device. In any case, the jacket element is preferably arranged at a distance from the induction coil in order not to bridge its turns. If the jacket element is fastened directly to the induction coil, preferably non-conductive fastening and / or spacer elements are provided for this purpose.

Preferably, the induction coil is embedded in an insulator material or potted with an insulator material. In both cases, the induction coil is preferably spaced from the shell member by the insulator material. This ensures that the conductive ferromagnetic jacket element has no electrical contact with the induction coil, so that a short circuit between the induction coil and the workpiece to be heated is avoided via the jacket element. A bridging of the turns of the induction coil through the jacket element is thus avoided.

If non-conductive fastening and / or spacing elements are provided for fastening the jacket element to the induction coil, these are preferably heat-resistant, so that they can assume a temperature of the jacket element and the induction coil during operation without deformation or damage. The same naturally applies to an insulator material in which the induction coil is embedded or with which it is cast.

A device is also preferred, which is characterized in that the jacket element has a support surface which faces a workpiece to be heated. The geometry of the support surface is formed complementary to a contour of a region of the workpiece to be heated. This makes it possible to apply the support surface areally to the area to be heated. The area to be heated is preferably at the same time an area in which the workpiece is to be formed, in particular to be folded. The flat contact of the support surface at the area to be heated allows a uniform heat input in these, at the same time a deformation or bulging of the area is prevented because it is supported by the support surface. This is possible because the support surface conforms to the contour, thus fits precisely to the area to be heated. Accordingly, a formation of heat-induced deformations is effectively prevented by this direct contact in connection with the conformal system to the area to be heated.

The support surface of the jacket element is not necessarily curved. In one exemplary embodiment of the device, a planar support surface is preferred in order to be able to heat planar workpiece surfaces quickly and in a targeted manner without these deforming in a thermally induced manner. Of course, it is possible in other embodiments of the device or embodiments of the method that the support surface is curved and adapted to a curved contour of the region to be heated of the workpiece.

It is readily possible to form the inductor and the jacket element in such a way that the heat input into the workpiece is limited locally to a region to be heated, so that it is not necessary to cover large areas of the workpiece or of the tool, and thus of the device. to cool. Since inductive heating can be effected very quickly overall, the device can be used quickly and in a targeted manner locally.

A device is also preferred in which the inductor is displaceable relative to a workpiece to be heated. It is possible that the inductor is arranged displaceably on the device, so that it can be displaced relative to this stationary workpiece. It is also possible that the workpiece is displaceable relative to the device can be accommodated, so that it is displaceable relative to the fixed inductor. In another embodiment it is possible that both the workpiece and the inductor are held displaceable relative to each other. Overall, a displaceable design of the inductor is preferred if a deformation of the workpiece - in particular a pressing part - along a forming direction to be performed in the manner of folding, wherein a folded edge is successively generated along a forming direction by displacement of a seaming tool. In this case, it is advantageous if, in any case, the inductor, together with the jacket element, can be displaced in advance, so to speak, to the folding tool, in order to always be able to heat the area to be reformed next. In this case, the support surface of the jacket element is preferably designed such that it has a shape corresponding to the radius of the fold edge to be formed corresponding concavity, whereby a rich, flat and contour-fair investment is guaranteed. In one embodiment, it is also possible that the inductor is provided nacheilend together with the jacket element the folding tool to allow heating after forming.

The device is preferably designed as a heating station. Regardless of whether it is designed as a heating station or otherwise, the heating of the workpiece carried out by means of the device does not necessarily serve to transform it. Rather, it is also possible that the workpiece is heated to adjust its properties for other later applications, such as an impact test.

The object is also achieved by a forming device for inductive heating and forming metal workpieces with the features of claim 6 is provided. The forming device, which is particularly suitable for inductive heating and forming of sheets or stampings, is characterized by a device according to one of the features described above.

Preferably, the forming device further comprises at least one forming tool, with which the workpiece is deformable. Particularly preferably, the forming tool is displaceable along a deformation direction in order to reshape the workpiece in the manner of folding. In this case, preferably, the inductor is formed together with the jacket element before or after the forming tool displaceable. Overall, with regard to the forming device realize the advantages that have already been described in connection with the device.

Finally, the object is also achieved by providing a method for heating metallic workpieces, in particular sheets or pressed parts, with the steps of claim 7. In this case, a region of a workpiece, in particular of a sheet metal or pressed part is heated by a support surface of a shell element is applied to the area surface, wherein the geometry of the support surface is complementary to a geometry of the area, and wherein the shell element comprises a ferromagnetic material. It surrounds an induction coil at least on a side facing the area. The area is heated by means of the induction coil. In this case, the workpiece undergoes a uniform heat input in the region to be heated, wherein despite the heat input, a shape of the heated point is maintained. This is possible because a true-to-contour installation or a contingent direct contact of the support surface of the jacket element is realized at the area to be heated. Thus, the formation of heat-induced deformations can be prevented. At the same time, the heat input is locally limited to the area to be heated, so that it is unnecessary to cool large areas of the workpiece and possibly also of the tool. The warming is therefore fast and targeted use. Incidentally, the advantages already described in connection with the device are realized.

The region in which the workpiece, in particular the sheet metal or pressed part, is heated, is preferably a region to be reshaped, which is formed after the heating, in particular folded.

Alternatively, it is possible that mechanical and / or material properties in the area to be heated for later applications, such as an impact test, should be set by the heating.

Workpieces are particularly preferably heated and, if necessary, formed by means of the process, which comprise or consist of at least one curable or non-hardenable aluminum alloy. It is possible to use with the help of heating in particular the formability of such a workpiece by dissolution of MgSi ₂ phases in 6xxx alloys or for targeted and local softening of edges of angled regions in curable and non-hardenable alumium alloys. It is also possible to adjust material properties defined by the heating in at least one region of the workpiece, in particular a sheet or pressed part, in particular if this comprises a hardenable or non-hardenable aluminum alloy or consists of such.

A method is also preferred, which is characterized in that the region to be heated is indirect with the aid of the induction coil is heated. In this case, the jacket element is heated inductively directly by the induction coil, wherein the region to be heated is heated by thermal contact with the jacket element, ie in particular by heat conduction, but optionally also by heat radiation and / or convection. In this case, the alternating electromagnetic field of the induction coil to the workpiece is substantially shielded from the jacket member; Preferably, the entire energy emitted by the alternating electromagnetic field energy is thus coupled into the jacket element as heat energy. Since this heats up very quickly, however, a rapid and targeted heating of the area to be heated is also possible. This approach is also referred to as indirect inductive heating or indirect induction heating. Of course, an embodiment of the device or an embodiment of the method is possible in which the electromagnetic alternating field of the induction coil acts both on the jacket element and on the workpiece, so that the workpiece is heated at least inductively.

It is also preferred a method in which the workpiece, in particular the sheet, is formed before heating. In this case, the heating serves a heat treatment of the formed workpiece. Alternatively or additionally, it is possible that the workpiece is formed during heating. Particularly preferably, the workpiece is alternatively formed after heating. In this case, the heating essentially serves to expand the formability of the workpiece or to increase an achievable degree of deformation.

Finally, a method is preferred which is characterized in that the workpiece, in particular the sheet, is formed along a forming direction, in particular in the manner of a fold. In this case, the induction coil is displaced together with the jacket element along a deformation direction relative to the workpiece. As already described, a displacement of the induction coil is possible together with the jacket element relative to the fixed workpiece, wherein it is also possible that the workpiece is displaced relative to the fixed induction coil with a likewise fixed jacket element. A displacement of both the induction coil and the jacket element and the workpiece is possible. Preferred is an embodiment of the method and an embodiment of the device, in which a forming tool is displaceable relative to the workpiece along the forming direction. It is then possible to move the induction coil together with the jacket element before or after the forming tool in order to be able to deform the workpiece before or after the heating. Finally, it is possible that the induction coil and the jacket element are integrated into the forming tool and can be displaced together with it, so that in particular a deformation of the workpiece during heating is possible.

The invention will be explained in more detail below with reference to the drawing.

Showing:

1 a schematic representation of a first embodiment of a device for inductive heating or a first embodiment of the method;

2 a schematic representation of a second embodiment of an apparatus or a second embodiment of the method;

3 a schematic representation of a third embodiment of an apparatus or a third embodiment of the method;

4 a schematic representation of a fourth embodiment of an apparatus or a fourth embodiment of the method, and

5 a schematic representation of a fifth embodiment of a device or a fifth embodiment of the method.

1 schematically shows a first embodiment of a device 1 for inductive heating of a workpiece 3 that have an inductor 5 with an induction coil 7 having. It is a jacket element 9 provided that the induction coil 7 not just on a workpiece 3 facing side with a floor element 9a but also in a peripheral area with a collar 9b embraces. The jacket element 9 consists of a ferromagnetic material, preferably of steel.

It is in the illustrated embodiment as a hood on the induction coil 7 placed.

The induction coil is preferred 7 embedded in a non-illustrated, non-conductive material, in particular an insulating material or potted with this. This prevents the jacket element 9 through the induction coil 7 electrically contacted, so on the one hand turns of the induction coil 7 not be bridged and on the other a short circuit between the induction coil 7 and the workpiece 3 is avoided. This can also be achieved by, in another embodiment, the induction coil 7 by at least one holding or spacer element of the jacket element 9 is spaced, wherein the holding or spacer element is non-conductive.

The workpiece 3 here includes an inner panel 11 that with an outer panel 13 to be joined by folding. For this purpose, the outer panel 13 in the region of a folded edge 15 formed and on the inner sheet 11 folded over.

This is preferably effected by an unillustrated forming tool along a perpendicular to the image plane of the figure extending extension of the folded edge 15 is shifted, with the outer panel 13 successively regionally transformed. Accordingly, the device 1 , in particular the inductor 5 together with the jacket element 9 along the folded edge 15 in order to heat these in a timely manner in the area to be reshaped or reshaped.

On the jacket element 19 is a support surface 17 provided, the geometry of which is complementary to the contour of the folded edge 15 is trained. The support surface 17 is therefore flat against the folded edge 15 can be applied or has a radius of the folded edge 15 formnegative concavity.

This will ensure that the workpiece 3 not by means of the device 1 registered heat is deformed or bulged because it is contoured by the support surface 17 is supported in the heated area.

The deformation is therefore exclusively and defined by the forming tool, not shown in the figure.

2 shows a schematic representation of a second embodiment of the device 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. The device according to 2 heated workpiece is flat here and especially designed as a sheet. The support surface is also corresponding 17 of the jacket element 9 here just trained to unwanted deformation of the workpiece 3 to avoid in the area to be heated.

Preferably, a counter element 19 provided, which - of the jacket element 9 Seen from - on an opposite side of the workpiece 3 is arranged so that holding forces between the jacket element 9 and the counter element 19 buildable and in the workpiece 3 can be introduced. In this way is an undesirable deformation of the workpiece 3 when heating particularly efficient avoidable.

3 shows a schematic representation of a third embodiment of the device 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. Again, a flat, preferably designed as a sheet workpiece 3 using the inductor 5 , the induction coil 7 and the jacket element 9 heated. The support surface is also corresponding 17 just trained.

Instead of the counter element 19 Here, however, is a second arrangement of a second inductor 5 ' with a second induction coil 7 ' and a second jacket member 9 ' on one - of the shell element 9 seen from - opposite side of the workpiece 3 intended. Also the second jacket element 9 ' has a second, planar support surface 17 ' on, where - as already in connection with the counter element 19 in 2 described - holding forces between the first shell element 9 and the second jacket member 9 ' buildable and in the workpiece 3 can be introduced. Using the two inductors 5 . 5 ' is the workpiece 3 in the area to be heated especially quickly and homogeneously heated on both sides. At the same time a deformation by the support of the workpiece 3 between the jacket elements 9 . 9 ' , in particular between the support surfaces 17 . 17 ' effectively prevented.

4 shows a schematic representation of a fourth embodiment of the device 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. In the embodiment of the method shown here or by means of the illustrated embodiment of the device 1 becomes a workpiece 3 , which is formed as a pressed part, in an edge region 21 heated. The support surface 17 of the jacket element 9 is contour-right or shape-negative to the edge area 21 designed to ensure a full, flat contact with this and so a deformation of the workpiece 3 to counteract heating.

In order to be able to prevent the deformation particularly effectively, it is preferable in turn to have a counter-element 19 provided, which also conform to the contour or shape negative to the edge region 21 is formed, wherein it on one - of the shell element 9 seen from - opposite side of the workpiece 3 is arranged. Also in the embodiment shown here are holding forces between the jacket element 9 and the counter element 19 buildable and in the edge area 21 into the workpiece 3 introduced.

5 shows a fifth embodiment of the device 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. Also in this embodiment or in the schematically illustrated embodiment of the method is preferably formed as a press part workpiece 3 in an edge area 21 warmed up, in contrast to 4 instead of the counter element 19 a second arrangement of a second inductor 5 ' , a second induction coil 7 ' and a second jacket member 9 is provided. The second jacket element 9 ' has a second support surface 17 ' on, as well as the first support surface 17 contour-right or shape-negative to the edge region 21 and to rest on a shell element 9 opposite side of the workpiece 3 is provided or designed. Accordingly, here are holding forces between the first support surface 17 and the second support surface 17 ' buildable in the edge area 21 can be initiated. In this way, a possible deformation of the workpiece 3 effectively prevented during heating. At the same time, the heating is very efficient and homogeneous, since the heat from both sides into the workpiece at the same time 3 in the edge area 21 is initiated.

Preferably, the sheath elements shield 9 . 9 ' in all embodiments, the alternating electromagnetic field, which by the induction coils 7 . 7 ' is generated completely from the workpiece 3 so that only the jacket elements 9 . 9 ' be heated inductively. The workpiece 3 on the other hand is preferred exclusively by the contact with the jacket elements 9 . 9 ' heated, which is also referred to as indirect inductive heating.

In particular, in the embodiments or embodiments of the 2 to 5 The heating is done by means of the device 1 not necessarily the forming of the workpiece 3 but preferably the setting of desired material technical and / or mechanical properties of the same, which are needed in a simultaneous or subsequent application. Such an application may include, for example, an impact test.

Overall, it shows up with the help of the device 1 , The Umformeinrichtung and the method is possible, the workpiece 3 targeted, fast and reliable local heating in a region to be heated, with a uniform heat input is possible. Heat induced deformations or bulges are caused by the direct contact of the workpiece 3 with the support surface 17 or by the contour-faithful system on the workpiece 3 safely avoided.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008032911 A1 [0002]
• DE 102012003667 [0005]

Claims (10)

Contraption ( 1 ) for inductive heating of metallic workpieces ( 3 ), in particular of sheet metal or pressed parts, with at least one inductor ( 5 ), which has an induction coil ( 7 ), characterized by a induction coil ( 7 ) at least on a workpiece to be heated ( 3 ) facing side encompassing jacket element ( 9 ) comprising a ferromagnetic material. Contraption ( 1 ) according to claim 1, characterized in that the jacket element consists of a ferromagnetic material. Contraption ( 1 ) according to one of the preceding claims, characterized in that the jacket element ( 9 ) as a hood on the induction coil ( 7 ) is attached. Contraption ( 1 ) according to one of the preceding claims, characterized in that the jacket element ( 9 ) a workpiece to be heated ( 3 ) facing support surface ( 17 ) whose geometry is complementary to a contour of a region of the workpiece to be heated ( 3 ) is formed, so that the support surface can be applied flat to the area to be heated. Contraption ( 1 ) according to one of the preceding claims, characterized in that the inductor ( 5 ) relative to a workpiece to be heated ( 3 ) is displaceable. Forming device for inductive heating and forming of metallic workpieces ( 3 ), in particular of sheet metal or pressed parts, characterized by a device ( 1 ) according to one of claims 1 to 5. Method for heating metallic workpieces ( 3 ), in particular sheet metal or pressed parts, comprising the following steps: heating a region of a workpiece ( 3 ), in particular a sheet, in that a support surface (11) complementary to a geometry of the region (FIG. 17 ) of a jacket element ( 9 ), which comprises a ferromagnetic material and an induction coil ( 7 ) surrounds at least on a side facing the area, is applied to the area surface, wherein the area by means of the induction coil ( 7 ) is heated. A method according to claim 7, characterized in that the area by means of the induction coil ( 7 ) is indirectly heated by the jacket element ( 9 ) through the induction coil ( 7 ) is heated inductively, wherein the region by thermal contact with the jacket element ( 9 ) is heated. Method according to one of claims 7 and 8, characterized in that the workpiece ( 3 ), in particular the sheet, before heating, during heating and / or after heating formed, in particular, is folded. Method according to one of claims 7 to 9, characterized in that the workpiece ( 3 ), in particular the sheet, is formed along a deformation direction, wherein the induction coil ( 7 ) together with the jacket element ( 9 ) along the forming direction relative to the workpiece ( 3 ) is relocated.

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