Method for manufacturing a sheet metal blank

Abstract

Method for producing a sheet metal blank (12) with a predetermined contour, comprising the following steps: - Providing a sheet metal strip (2) in the form of a sheet metal spool (1) or a coil, wherein the sheet metal strip (2) is provided on its surface with a protective layer (13) made of a material that differs from the material of the sheet metal strip (2), - Unwinding the sheet metal strip (2) from the sheet metal spool (1) or the coil, - Straightening the sheet metal strip (2) unwound from the sheet metal spool (1) or the coil, - continuous movement of the sheet metal strip (2) along a transport direction (x), - a) concurrent surface removal of material on a top surface (O) of the sheet metal strip (2) in at least one predetermined surface section (16) by ablation using a first laser in a first removal device (4), wherein the first laser is moved along the transport direction (x) and along a y-direction extending perpendicular to it, and subsequently - b) synchronous cutting of the sheet metal strip (2) along a cutting path (11) corresponding to the contour of the sheet metal blank (12) by means of at least one second laser, wherein the second laser is moved along the transport direction (x) and along the y-direction extending perpendicular to it, in a cutting device (8) provided downstream of the first ablation device (4), - wherein the production of the surface section (16) of an upstream sheet metal blank (12) and the cutting of a downstream sheet metal blank (12) take place simultaneously.

Description

[0001] The invention relates to a method for producing a sheet metal blank.

[0002] According to the prior art, it is known, for example from WO 2009 / 105608 A1, to transport a sheet metal strip unwound from a spool or coil in one transport direction through a laser cutting device. Using the laser cutting device, sheet metal blanks of a predetermined contour are cut from the sheet metal strip while moving.

[0003] JP H10-15 682 A proposes removing a primer applied to a steel sheet using a first low-power laser beam. Simultaneously and in parallel, a second, higher-power laser beam follows the first laser beam and cuts the steel sheet.

[0004] Similarly, JP H10-71 481 A proposes irradiating the surface of a steel sheet with a laser beam to burn off its coating. The power of the laser beam is adjusted so that the steel sheet does not melt.

[0005] DE 10 2013 203 385 A1 proposes a method for cutting a sheet metal blank from a sheet metal strip, comprising the following steps: providing at least one laser cutting device with at least one laser cutting head movable both in the transport direction and in a direction perpendicular thereto, continuously measuring a path of the sheet metal strip with respect to the transport direction by means of a path measuring device provided upstream of the laser cutting device, and dynamically calculating the movements of the laser cutting head using the path measurement values ​​provided by the path measuring device.

[0006] US 2002 / 0 031 899 A1 relates to a method and apparatus for singulating semiconductor wafers. Using a laser beam, scribe lines are created in a layer arranged on a substrate. The substrate is then cut along the scribe lines using a saw blade to obtain the individual semiconductor wafers.

[0007] Today, sheet materials coated with a layer, such as an aluminum-silicon protective layer, are used, particularly for the production of sheet metal blanks in the automotive industry. Such an aluminum-silicon protective layer protects the steel surface against scaling and corrosion during hot forming.

[0008] When a sheet metal blank is welded to another sheet metal blank near its cut edge, material from the protective coating enters the weld area. Foreign phases form in the weld, which undesirably weaken the weld.

[0009] To counteract this, it is known from DE 10 2013 215 346 A1 to remove the aluminum-silicon protective layer by means of a laser along a path corresponding to a later weld seam.

[0010] Furthermore, it is known in the art to remove the protective layer using a laser or brush after producing a sheet metal blank using laser cutting, in predetermined sections along the cut edge. However, this is time-consuming and costly. Despite the removal of the protective layer, undesirable weak spots can occur in the area of ​​a subsequently produced weld seam.

[0011] The object of the invention is to eliminate the disadvantages of the prior art. In particular, it is intended to provide a method for producing a sheet metal blank that enables the efficient production of a weld seam with fewer defects in the area of ​​its cut edge.

[0012] This object is achieved by the features of patent claim 1. Advantageous embodiments of the invention emerge from the features of patent claims 2 to 7. - According to the invention, a method for producing a sheet metal blank with a predetermined contour is proposed, comprising the following steps: - Providing a sheet metal strip in the form of a sheet metal coil or a coil, wherein the sheet metal strip is provided on its surface with a protective layer made of a material different from the material of the sheet metal strip, - Unwinding the sheet metal strip from the sheet metal reel or coil, - Straightening of the sheet metal strip unwound from the sheet metal coil or reel, - continuous movement of the sheet metal strip along a transport direction, - a) concurrent superficial removal of material on an upper side of the sheet metal strip in at least one predetermined surface section by ablation using a first laser in a first removal device, wherein the first laser is moved along the transport direction and along a y-direction extending perpendicular thereto, and subsequently - b) cutting the sheet metal strip along a cutting path corresponding to the contour of the sheet metal blank by means of at least one second laser, wherein the second laser is moved along the transport direction and along the y-direction extending perpendicularly thereto, in a cutting device provided downstream of the first removal device, - wherein the production of the surface section for an upstream sheet metal blank and the cutting of a downstream sheet metal blank take place simultaneously.

[0013] In a departure from the prior art, the invention first removes material, such as an aluminum-silicon protective layer, from the surface of the sheet metal strip. The sheet metal strip is then cut according to the specified contour of the sheet metal blank. It has been shown that sheet metal blanks produced using the inventive method can be welded to other sheet metal blanks without the formation of undesirable, weakening foreign phases in the weld seam.

[0014] The term "surface removal" refers to the removal of material from the surface of the surface section to a depth of no more than 0.2 mm, preferably no more than 0.16 mm. The thickness of the sheet metal strip is considerably greater than the thickness of the layer removed from the surface. Surface removal does not create any perforations, slits, or similar in the sheet metal strip. "Surface removal" can also be used to remove oxide layers, oil layers, paint layers, contaminants, or similar from the surface of the sheet metal strip.

[0015] According to one embodiment of the invention, at least a first layer provided on the upper side is removed in step a). It is also possible for a second layer interposed between the first layer and a sheet material to be removed in step a). The first and, if applicable, the second layer differ in their composition from the sheet material to which they are applied. The first layer can be, for example, an aluminum-silicon protective layer or a zinc protective layer. The second layer can be an intermediate layer made of FeAl3, Fe2Al3, which is arranged between the sheet material and an aluminum-silicon protective layer. The first layer can have a thickness in the range from 0.01 to 0.1 mm and the second layer can have a thickness in the range from 0.005 to 0.05 mm.

[0016] According to the invention, in step a), the removal by ablation is carried out using a first laser. The first laser can be a pulsed laser, generating, for example, 10 to 1000 pulses / mm. The first laser can have a power in the range of 100 to 2000 W, preferably 850 to 1600 W. It can be a gas discharge laser, e.g., a CO2 laser, or a solid-state laser, e.g., a fiber, diode, disk, or rod laser.

[0017] Additionally, it is also possible to perform the removal mechanically in step a). Rotating brushes or similar devices can be used for this purpose.

[0018] According to the invention, in step b), the sheet metal strip is cut using at least a second laser. This can be a conventional laser suitable for cutting sheet metal. To cut a sheet metal strip, the second laser is advantageously moved along the predetermined cutting path.

[0019] According to the invention, the sheet metal strip is continuously moved in the transport direction x, and both the ablation in the surface section and the creation of the cut along the cutting path are carried out concurrently. This means that, for example, in a conventional laser cutting device, a laser ablation station can be provided upstream of a laser cutting station. In the laser ablation station, material can be removed from the upper side of the sheet metal strip along the surface section. The surface section then moves to the area of ​​the downstream laser cutting station. There, the sheet metal strip is then cut. The creation of the surface section in an upstream sheet metal blank and the cutting of a downstream sheet metal blank occur simultaneously.

[0020] According to an advantageous embodiment of the invention, the surface section comprises a first path, wherein a course of the first path corresponds to at least a portion of the contour of the sheet metal blank, and wherein the sheet metal strip is cut such that the cutting path divides the first path along its first longitudinal direction. This makes it possible to weld sheet metal blanks to other sheet metal blanks along their cut edges.

[0021] According to a further advantageous embodiment of the invention, the cutting path runs approximately centrally between the edges of the first path. In this case, the cutting path has a maximum distance from both edges. This safely and reliably prevents unwanted contamination on the surface of the sheet metal strip, particularly components of a protective layer, from entering the area of ​​the cutting edge.

[0022] A first width B1 of the first path, which extends perpendicular to the first longitudinal direction of the first path, is greater than a second width B2 of the cutting path, which extends perpendicular to a second longitudinal direction of the cutting path. The following advantageously applies to the ratio between the first width B1 and the second width B2: B1 / B2=A, where A is a value in the range from 2 to 100.

[0023] The first width B1 is typically 0.5 to 4.0 mm. The second width B2 is typically 0.05 to 0.7 mm.

[0024] Typically, a sheet metal strip is coated with a protective layer not only on its upper side, but also on its underside opposite the upper side. In step a), material can advantageously be removed from an underside of the sheet metal strip along a second path, wherein the second path, viewed from above, is essentially congruent with the first path. The aforementioned advantageous embodiments can also be used to produce the second path in a manner analogous to the production of the first path.

[0025] According to one embodiment, the cutting path can also surround the at least one surface section. In this case, the surface section is advantageously round. The material on the surface of the sheet metal strip is expediently removed in several consecutive, predetermined surface sections. In this case, another sheet can be placed on the sheet metal blank in such a way that the surface sections are covered. The additional sheet can then be welded to the sheet metal blank using a spot welding process.

[0026] The method according to the invention enables the production of sheet metal blanks whose surface is removed along the surface sections. In the aforementioned surface sections, the sheet metal blank can be joined to another sheet metal blank by welding, whereby the resulting weld seam is essentially free of foreign phases that could weaken the weld seam. The method enables the rapid and efficient production of sheet metal blanks that are to be welded.

[0027] A first removal device comprises a first movement device for moving a first removal tool in the transport direction x and in a y-direction perpendicular thereto according to the predetermined first path. The movement device can be a conventional movement device with which, for example, a laser cutting head is moved along with a sheet metal strip to produce a predetermined contour. A suitable movement device is known, for example, from US 2010 / 0181165 A1. A tool is attached to an arm or bridge so that it can be moved in the y-direction, which in turn can be moved in the x-direction. The movements are usually carried out by means of servo motors controlled by a computer-aided controller. However, robots or the like can also be used as the movement device. In this respect, reference is made, for example, to the disclosure content of US 2010 / 0122970 A1.

[0028] According to one embodiment, the surface section is a first path corresponding to at least a portion of the contour of the sheet metal blank, and the cutting path divides the first path along its first longitudinal direction. This enables rapid and efficient removal of material in an area of ​​the cut edges of the sheet metal blank. In contrast to the prior art, it is no longer necessary to appropriately position a previously cut sheet metal blank, clean its cut edges, and superficially remove the top and bottom surfaces in the area of ​​the cut edges. The proposed device enables rapid and efficient production of sheet metal blanks.

[0029] According to a further embodiment of the invention, a second removal device is provided for the superficial removal of material on an underside of the sheet metal strip opposite the upper side along a further surface section forming a second path, wherein the second path, when viewed from above onto the first path, is substantially congruent with the first path. The second removal device enables the removal of material from the underside of the sheet metal strip in a manner analogous to the first removal device. The second removal device expediently comprises a second movement device for moving a second removal tool in the x and y directions according to the predetermined second path. The first and second removal devices can be coupled to one another in terms of control technology and / or mechanically, in particular for producing congruent paths.

[0030] The first and / or second removal tool is expediently a first laser or a grinding tool. A pulsed laser, such as that known from DE 10 2013 215 346 A1, can be used as the first laser. Material removal can be assisted by compressed air or inert gas, each at a pressure of at least 3 bar, and at an acute angle to the laser beam impinging on the surface of the sheet metal strip.

[0031] The cutting device comprises at least one second laser that can be moved in the x- and y-directions according to the specified cutting path. A conventional laser suitable for cutting sheet metal materials can be used as the second laser. It is also conceivable to use a mechanical cutting device, such as a reciprocating shear or the like, as the cutting device.

[0032] Furthermore, for carrying out the method according to the invention, a controller can be provided to control the movements of the first removal tool and the cutting tool. The controller also makes it possible to additionally control the movements of the second removal tool. The controller is, for example, a computer in which the coordinates of the first path and the cutting path are stored. The coordinates correspond to the predetermined contour of the sheet metal blank. If the sheet metal strip is moved continuously, the movement paths of the cutting and removal tools are automatically recalculated or corrected by the controller in accordance with the feed path of the sheet metal strip. To ensure particularly precise correction or recalculation, a measuring device can be provided to measure a path of the sheet metal strip in the x-direction.Furthermore, a device can be provided for transmitting path measurements measured by the measuring device to the control system. The control system conveniently controls all movements of the cutting and removal tools simultaneously. This enables particularly precise adherence to the specified contour of the sheet metal blank and the position of the cutting path within the respective path.

[0033] An embodiment of the invention is explained in more detail below with reference to the drawings. They show: Fig. 1 a schematic plan view of an apparatus for carrying out the method according to the invention, Fig. 2 a cross-sectional view through the sheet metal strip according to the section line AA' in Fig. 1, Fig. 3 a plan view of a first sheet metal plate and Fig. 4 a top view of a second sheet metal plate.

[0034] Fig. 1 shows a schematic plan view of an apparatus for carrying out the method for producing a sheet metal blank. The reference numeral 1 designates a sheet metal coil or coil which is rotatable about an axis Z. A sheet metal strip 2 unwound from the coil 1 extends in a transport direction or x-direction. Downstream of the coil 1, a roller straightening machine 3 is provided, with which the sheet metal strip 2 is straightened and, preferably continuously, transported in the x-direction. Downstream of the roller straightening machine 3, a first removal device 4 is provided, which is indicated by a broken line. The first removal device 4 comprises a first bridge 5 which spans the sheet metal strip 2 and extends in a y-direction perpendicular to the x-direction. The first bridge 5 can be moved back and forth in the x-direction, i.e. also counter to the transport direction x.Attached to the first bridge 5 is a first removal tool 6, which is movable back and forth in the y-direction across the entire width of the sheet metal strip 2. Reference numeral 7 denotes a first path, which was created by superficial removal on the upper side O of the sheet metal strip 2 using the first removal tool 6.

[0035] Downstream of the first removal device 4, a cutting device 8 is provided, which is again indicated by a broken line. The cutting device 8 comprises a second bridge 9, which overlaps the sheet metal strip 2 in the y-direction. The second bridge 9 can be moved back and forth in the y-direction, i.e., also counter to the transport direction x. A cutting tool 10 is attached to the second bridge 9 and can be moved back and forth in the y-direction. Reference numeral 11 designates a cutting path produced by the cutting device 10. Reference numeral 12 designates a first sheet metal blank which has been completely cut out of the sheet metal strip 2. The contour of the first sheet metal blank 12 is delimited by the cutting path 11. The first path 7 extends along a section of the cutting path 11.

[0036] Instead of the aforementioned gantry device, which comprises a bridge and a carriage movable back and forth thereon, it is of course also possible to move the removal and / or cutting tools along the specified paths, for example, by means of a robot or other suitable device. The movements of the tools can also be controlled, for example, based on a polar coordinate system.

[0037] Fig. 2 shows a sectional view along the section line AA' in Fig. 1. The first path 7 has a first width B1, which is greater than a second width B2 of the cutting path 11 or the cut. The sheet metal strip 2 consists of a steel material 12a, which is coated on its upper side O and on the opposite underside U with a protective layer 13, e.g., an aluminum-silicon protective layer. Opposite the first path 7, a second path 14 is located in a congruent arrangement. The protective layer 13 is removed along the first path 7 and the second path 14.

[0038] Fig. 3 shows a plan view of the first sheet metal blank 12. This again makes it clear that the first path 7 partially adjoins a contour of the first sheet metal blank 12 delimited by the cutting path 11.

[0039] Fig.4 shows a plan view of a second sheet metal blank 15. The second sheet metal blank 15 has, within a contour defined by the cutting path 11, a plurality of surface sections 16 in which the protective layer 13 of the sheet metal strip 2 has been removed from the upper side. The surface sections 16 have the shape of a short path, a round, or an oval shape. The surface sections 16 serve to produce a spot weld connection with a further sheet metal part 17 to be connected to the second sheet metal blank 15, which is indicated here by a broken line. In the second sheet metal blank 15, the surface sections 16 do not border on the circumferential cutting edge of the second sheet metal blank 15 created by the cutting path 11. The function of the device is as follows:

[0040] The sheet metal strip 2 unwound from the spool 1 is straightened by means of the roller straightener 3 and simultaneously transported continuously in the transport direction x. In the first removal device 4, a first removal tool 6, for example a suitable first laser, is moved along a predetermined contour of the first sheet metal blank 12 to be produced. The corresponding movements of the first bridge 5 and the first removal tool 6 are controlled by a controller (not shown here). Opposite the first removal device 4, a second removal device (not shown here) can be provided, with which a second path 14 is removed on an underside U of the sheet metal strip 2 opposite the top side O. - It is not necessary to provide a second removal device for all applications.

[0041] After the at least first path 7 has been created, the sheet metal strip 2 is fed to the downstream cutting device 8. The cutting device 8 creates the cutting path 11, which corresponds to the predetermined contour of the sheet metal blank 12 to be produced. The cutting path 11 divides the first path 7 along its longitudinal direction. As a result, the protective layer 13 is already removed in the area of ​​the cutting edge before the cutting path 11 is created. The subsequent creation of the cutting path 11 using the cutting device 10 prevents any contaminants from entering the area of ​​the cutting edge.

[0042] According to a further function of the device, it is also possible to use the first removal tool 6 to remove surface sections 16 from the top side O of the sheet metal strip 2, which sections are in the shape of a short path, circular, or oval. Subsequently, the cutting path 11 can also be guided by means of the downstream cutting device 8 such that the cutting path 11 does not intersect the surface sections 16, i.e., the cutting path 16 surrounds the surface sections 16.

[0043] Although not shown in the figures, it is of course also possible to produce sheet metal blanks using the method that have, at least in sections, a first path 7 in the region of the cutting path 11, as well as surface sections 16 outside the cutting path 11 but within the contour. In addition, such sheet metal blanks can also be provided with a second path 14 in the region of the cutting edges, which is opposite the first path 7.

[0044] The movements of the cutting device 10 are controlled by the controller in a similar manner to those of the first removal tool 6. For this purpose, a measuring device (not shown in detail here), for example, a drag wheel resting on the sheet metal strip, can be provided. The measured displacement values ​​can be transmitted to the controller so that the movements of the first removal tool 6 and the cutting device 10 can be controlled in a suitable manner.

[0045] The device and method enable the rapid and efficient production of sheet metal blanks in which material has been removed from at least some sections, at least from the top surface. The material can be, in particular, a protective layer, such as an aluminum-silicon protective layer or a zinc protective layer. Such sheet metal blanks can be joined to another sheet metal blank by welding in the area of ​​the surface sections. The resulting welded joint is characterized by a particularly low defect content. Undesirable foreign phases within the weld seam can be largely avoided. List of reference symbols 1 coil 2 sheet metal strips 3 roller straightening machines 4 first removal device 5 first bridge 6 first removal tool 7 first path 8 Cutting device 9 second bridge 10 cutting tools 11 Cutting path 12 first sheet metal plate 12a steel material 13 Protective layer 14 second path 15 second sheet metal plate 16 Area section 17 Sheet metal part B1 first width B2 second width O Top U bottom x Transport direction Z axis

Claims

[1] Method for producing a sheet metal blank (12) with a predetermined contour, comprising the following steps: - Providing a sheet metal strip (2) in the form of a sheet metal coil (1) or a coil, wherein the sheet metal strip (2) is provided on its surface with a protective layer (13) made of a material different from the material of the sheet metal strip (2), - Unwinding the sheet metal strip (2) from the sheet metal coil (1) or the coil, - straightening the sheet metal strip (2) unwound from the sheet metal coil (1) or the coil, - continuous movement of the sheet metal strip (2) along a transport direction (x), - a) concurrent superficial removal of material on an upper side (O) of the sheet metal strip (2) in at least one predetermined surface section (16) by ablation using a first laser in a first removal device (4), wherein the first laser is moved along the transport direction (x) and along a y-direction extending perpendicular thereto, and subsequently - b) cutting the sheet metal strip (2) along a cutting path (11) corresponding to the contour of the sheet metal blank (12) by means of at least one second laser, wherein the second laser is moved along the transport direction (x) and along the y-direction extending perpendicularly thereto, in a cutting device (8) provided downstream of the first removal device (4), - wherein the production of the surface section (16) in an upstream sheet metal blank (12) and the cutting of a downstream sheet metal blank (12) take place simultaneously. [2] Method according to claim 1, wherein in step a) at least one protective layer (13) provided on the upper side (O) is removed. [3] Method according to one of the preceding claims, wherein in step a) a second layer interposed between the protective layer (13) and a steel material (12a) is removed. [4] Method according to one of the preceding claims, wherein the surface section (16) comprises a first path (7), wherein a course of the first path (7) corresponds at least to a portion of the contour of the sheet metal blank (12), and wherein the sheet metal strip (2) is cut such that the cutting path (11) divides the first path (7) along its first longitudinal direction. [5] Method according to one of the preceding claims, wherein the cutting path (11) surrounds the at least one surface section (16). [6] Method according to one of claims 4 or 5, wherein the following applies to a ratio between a first width (B1) extending perpendicular to the first longitudinal direction of the first path (7) and a second width (B2) extending perpendicular to a second longitudinal direction of the cutting path (11): B1 / B2=A, where A is a value in the range from 2 to 100. [7] Method according to one of claims 4 to 6, wherein in step a) material is removed from an underside (U) of the sheet metal strip (2) along a further surface section (16) forming a second path (14), wherein the second path (14) is substantially congruent with the first path (7) in a plan view of the first path (7).

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