EXTENDING STRIP-SHAPED MATERIALS

Description

[0001] The present invention relates to a device for feeding sheet metal to a processing unit. The present invention further relates to a system for processing sheet metal and a method for feeding sheet metal to a processing unit.

[0002] Due to technological advancements and political mandates, electromobility has become increasingly important in recent years. In the production of vehicles (cars, trucks, motorcycles, and bicycles, etc.) as well as in other sectors, the manufacturing process of electric motors, alongside the development and production of batteries, is a highly relevant factor.

[0003] The laminated cores in the rotor or stator of an electric motor comprise a multitude of thin sheets (also known as electrical steel sheets). These electrical steel sheets exhibit excellent properties in conducting and amplifying magnetic fields, with the composition and stress-free state of the sheets, as well as their insulation from one another, influencing the efficiency of the electric motor.

[0004] In the mass production of such lamella stacks, as well as other sheet metal components, large (transfer) presses are often used in which strip-shaped material (usually coming from a roll or coil) is frequently punched and formed in several stages. Since the rolls on which the sheet metal is wound only contain a certain amount of sheet (length), the press must be stopped when the end of the sheet on the roll is reached. The remaining sheet metal must then be unwound. Conversely, the new sheet metal can only be fed in or processed once it has passed through the entire length of the press. This leads to considerable scrap of unused sheet metal, as well as productivity losses due to downtime for setup, during which the machines are not operating productively.

[0005] US Patent 3,719,542 A, which forms the basis for the preamble of claims 1 and 10, discloses a device for joining the rear end of one metal strip to the front end of a subsequent metal strip. For this purpose, the unusable portions of the ends to be joined are cut off, and adhesive tape is applied across the entire width of at least one of the ends. The ends are aligned so that they touch, preferably one above the other, and held together by a pressure element. The adhesive tape is laid across the width of the ends of the metal strips and cut before being applied to the strip, so that it extends exactly across the width of the strip.

[0006] DE 694 09 772 T2 discloses a system for joining and welding two wound metal strips together using a laser beam to produce a continuous metal strip.

[0007] German patent DE 29 49 095 B1 discloses a device for joining two strips of material. The end and beginning sections of the strips are cut off. Subsequently, the joints of the two strips are welded together in their cutting planes. A laser device movable transversely to the longitudinal direction of the strip is provided as both the cutting and welding device.

[0008] EP 2 202 025 B1 discloses a method and a device for joining metal strips by friction spot welding.

[0009] In KR 2010 0073270 A, a method for welding along a line and a device for carrying out this method are disclosed.

[0010] Based on this, the present invention aims to provide an approach for feeding sheet metal to a further processing unit in which unproductive downtime is avoided and material waste is reduced. In particular, faster processing is to be enabled compared to previous approaches. This, in turn, should enable the efficient production of sheet metal components.

[0011] To solve this problem, the present invention relates in a first aspect to a device for feeding sheet metal to a further processing unit, with a feeding unit for receiving a first sheet from a first roll of wound sheet metal and a second sheet from a second roll of wound sheet metal; a delivery unit for continuously conveying sheet metal to the processing unit; a first fixing unit for fixing a starting section of the second sheet on one side of the feeding unit when an end of the first sheet is reached; a second fixing unit for fixing a section of the first sheet on one side of the delivery unit when the end of the first sheet is reached; a processing unit for processing the end section of the first sheet and the starting section of the second sheet between the fixing units;and a joining unit for joining the machined end section with the machined start section between the fixing units, wherein the machining unit is configured for machining a first side of the start section and an opposite second side of the end section and for subsequently overlapping the machined start section and the machined end section, and the joining unit is configured for joining the sheets by bonding in the area of ​​the start section and the end section, characterized in that the machining unit (42) is configured with an undercut for producing an interlocking profile of the start section and the end section, ensuring that the thickness of a joining point is not increased or is only increased to an insignificant extent compared to the remaining sheet.

[0012] In another aspect, the present invention relates to a system for processing sheet metal, comprising: a device as defined above; a sheet metal storage unit for receiving sheet metal and providing a buffer, wherein the sheet metal storage unit is arranged between the device and a further processing unit.

[0013] Another aspect of the invention relates to a method designed according to the device for feeding sheet metal to a further processing unit.

[0014] Preferred embodiments of the invention are described in the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. In particular, the device, the system, and the method can be implemented according to the embodiments described for the system and the device in the dependent claims.

[0015] According to the invention, a device for feeding sheet metal is arranged between the sheet metal rolls and the downstream processing unit (for example, a continuous transfer press and / or a progressive die). This device receives sheet metal from a first sheet metal roll and from a second sheet metal roll. As soon as one end of the first sheet metal roll is reached on the first sheet metal roll or in the device, its end section is fixed in a second clamping unit. Additionally, the beginning section of the second sheet metal roll is fixed in a first clamping unit. The end section of the first sheet metal roll and the beginning section of the second sheet metal roll are then processed between the two clamping units and subsequently joined together. After joining, the sheet metal roll can be transferred to the downstream processing unit.

[0016] In contrast to previous approaches, the device or system according to the invention enables the continuous feeding of sheet metal to the processing unit. By connecting the first sheet to the second sheet when the first sheet runs out, sheet metal can be continuously fed to the processing unit. It is therefore unnecessary to remove the entire remaining sheet from the machine when the first sheet runs out, thus eliminating the need to interrupt production. Unproductive downtime is reduced. Furthermore, the amount of scrap is reduced or minimized. In particular, it eliminates the need to stop production altogether. In contrast to previous approaches, this increases the efficiency of sheet metal processing and the serial production of sheet metal components.

[0017] The joining of the new sheet metal section to the end of the old sheet metal section is carried out in such a way that the forming and punching process is not affected. This ensures that, when the processed end section is joined to the processed beginning section, the joining unit creates a joint that, on the one hand, transmits the process forces, such as those generated by strip tension, and on the other hand, also creates a seam that is formable and punchable. In contrast to previous approaches, the extension or joining process is not overlapping, so that the thickness of the sheet metal in the area of ​​the joint is not increased, or only minimally. The use of a sheet metal storage unit in the system according to the invention enables a continuous supply of sheet metal to the further processing unit.In particular, buffering can take place during the fixing of the initial section of the second sheet and the final section of the first sheet in the fixing units and the associated halting of the forwarding, so that sheet metal can be continuously supplied to the further processing unit.

[0018] In a non-inventive embodiment, the processing unit is designed for processing the butt edges of the sheet metal and subsequently bringing the butt edges together to create a zero gap. In a non-inventive embodiment, the joining unit is additionally or alternatively designed for joining the sheet metal at their butt edges by friction stir welding. In other words, the butt edges are brought so close together that friction stir welding is possible. The resulting joint achieves the required strength without the need for an overlap. This results in an efficiently implementable connection or joining of the sheet metal.

[0019] According to the invention, the processing unit is designed to process a first side of the initial section and an opposing second side of the final section, and subsequently to overlap the processed initial section and the processed final section. Furthermore, the joining unit is designed to connect the sheets by bonding in the area of ​​the initial and final sections. Preferably, an adhesive with rapid strength development can be used, in particular a polymerizing adhesive. A first side (top or bottom) of one sheet and an opposing second side (opposite top or bottom) of the other sheet are processed.

[0020] In particular, a scarf joint can be made.

[0021] After overlapping the processed start and end sections, they are joined by adhesive bonding. According to the invention, this process ensures that the thickness of the joint is not increased, or only minimally increased, compared to the remaining sheet metal. By selecting an appropriate adhesive chemistry, rapid strength development can be achieved and a high-strength bond created. This bond can withstand the process forces and advantageously also meets the requirements for heat resistance and compressive strength in subsequent sheet metal processing, for example, in a continuous transfer press.

[0022] According to the invention, the processing unit for creating an interlocking profile of the initial and final sections is designed with an undercut. This undercut enables better tensile force absorption. The adhesive bond serves only to join the sections, while the tensile forces are primarily absorbed by the interlocking profile. This results in higher tensile strength, ensuring sufficient protection against breakage or failure of the sheet metal during subsequent processing.

[0023] In a preferred embodiment, the first clamping unit and / or the second clamping unit comprises a hold-down device for clamping the sheet metal, preferably across its entire width. The hold-down device serves to fix or secure the sheet metal by bonding it in place. In other words, pressure is exerted on the sheet metal so that it cannot move, particularly not forwards or backwards in the direction of the strip's travel. A hold-down device enables efficient and cost-effective implementation of the clamping unit.

[0024] In a preferred embodiment, the processing unit is designed for machining the initial and final sections using a grinding, punching, milling, laser, plasma, waterjet, or sawing tool. Additionally or alternatively, the processing unit includes a tool head that moves orthogonally to the direction of travel of the sheet metal. Various methods can be used for machining the initial section. It is understood that combinations of these methods are also possible. In particular, the aforementioned methods enable efficient processing of the sheet metal. The use of a tool head that moves orthogonally to the direction of travel of the sheet metal allows for the efficient application of profiling or other machining operations. This results in particularly fast processing, thus enabling the continuous conveyance of the sheet metal for further processing.

[0025] In a preferred embodiment, the machining unit and the joining unit are implemented as a shared tool drive using different tools. A shared tool drive reduces costs by eliminating the need for additional mechanics. Furthermore, a precise machining sequence can be automatically maintained, thus improving reliability. This results in efficient implementation. It is possible to exchange the tools or to clamp different tools simultaneously, which can then machine the initial and final sections in parallel or sequentially.

[0026] In a preferred embodiment, the dispensing unit is designed to transfer the sheet metal to a sheet metal storage unit, a continuous transfer press, and / or a progressive die. In particular, it is possible for the sheet metal to first be transferred to a sheet metal storage unit, which can be configured, for example, as a roller storage unit with counter-moving rollers or in another manner. This sheet metal storage unit enables or supports continuous transfer. Further processing of the sheet metal takes place after the sheet metal storage unit. The sheet metal storage unit is thus used to buffer short downtimes due to the definition of the start and end sections and the joining process. This results in further improved efficiency.

[0027] In a preferred embodiment, the feeding unit is designed to receive an electrical steel sheet for a rotor and / or stator lamination stack of an electric motor. The device according to the invention is particularly advantageous in the mass production of electrical steel sheets for electric motors, where the sheets are punched and stacked. In this area, high machine utilization of the corresponding punching and stacking machine is advantageous, as this represents a significant cost factor. This results in further improved cost efficiency.

[0028] In a preferred embodiment, the feeding unit is designed to receive the first sheet from a first reel and the second sheet from a second reel. The reels are used, in particular, to hold sheet metal coils. Electrical steel sheets are usually supplied in the form of such coils, which can then be clamped directly. The inventive approach of connecting an initial section of the second sheet to an end section of the first sheet, combined with the use of two reels to hold two sheet metal coils, makes it possible to achieve increased efficiency. Production interruption is either unnecessary or minimal. The second sheet metal coil can be exchanged while the first is in use. Once the end of the first sheet metal coil is reached, it can be automatically connected to the beginning of the second sheet metal coil.Efficient manufacturing is achieved.

[0029] In a preferred embodiment, the system includes a processing unit for further processing the continuously conveyed sheet metal. The processing unit is preferably designed as a continuous transfer press and / or a progressive die for punching the sheet metal into a predefined shape. In particular, it is possible for a continuous transfer press and / or a progressive die to be used in the processing of electrical steel sheets for punching and stacking them for stators and rotors of electric motors. This results in an increase in the efficiency of stators and rotors in production.

[0030] In a preferred embodiment of the system according to the invention, the sheet metal storage unit is designed as a belt storage unit with several movable deflection rollers. The sheet metal storage unit is preferably designed to move the deflection rollers into a fully extended position after the end section has been joined with the beginning section. In this extended position, no buffer is provided, and the sheet metal is conveyed without bending. It is particularly advantageous to use a belt storage unit with movable deflection rollers. With such a belt storage unit, the rollers can be moved relative to each other to lengthen or shorten the path of the belt as it passes through the storage unit or the rollers. This allows for buffering of the sheet metal. During the positioning of the beginning and end sections in the positioning units, the belt storage unit is emptied by moving the deflection rollers towards each other.It is particularly advantageous if the deflection rollers are moved to a fully extended position during periods when buffering is not necessary—for example, when a sufficient supply of sheet metal is available and the end of the sheet is far from being reached—to allow the sheet metal to be conveyed without bending. While the sheet metal is not usually damaged by bending, challenges can arise in the downstream processing unit. To avoid this, the buffer is minimized when not needed.

[0031] In this context, a sheet metal component is understood to be, in particular, an electrical sheet, i.e., a thin sheet with good conductivity and reinforcement properties with respect to electric and magnetic fields. The sheet metal component may comprise one or more insulating layers. It is also possible that the device, system, or method according to the invention may be used for other types of sheet metal. A sheet metal roll is understood to be, in particular, a coil of wound sheet metal. A fixing unit may also be referred to as a clamping unit. Fixing can be understood, in particular, as securing, i.e., temporarily fastening. A starting or ending section comprises, in particular, a few centimeters in the region of the beginning or end of a sheet metal component that is supplied from the sheet metal roll with wound sheet metal.Continuous feeding of a sheet metal part means, in particular, feeding it without interruption or with very little interruption to production. Specifically, continuous feeding means that no sheet metal remnants need to be removed from the production line.

[0032] The invention is described and explained in more detail below with reference to some selected embodiments in conjunction with the accompanying drawings. These show: Figures 1a to 1c are a schematic representation of a system according to the invention for processing sheet metal; Figure 2 is a schematic representation of a device according to the invention for feeding sheet metal to a further processing unit; Figure 3 is a schematic representation of fixing an end section and a beginning section by means of a hold-down device; Figure 4 is a schematic representation of creating a technical zero gap by means of the hold-down device; Figures 5a and 5 are a schematic representation of a processing and joining of two sheets by friction stir welding, not according to the invention; Figures 6a to 6c are a schematic representation of processing and joining by adhesive bonding; Figure 7 is a schematic representation of four exemplary, interlocking profiles of the beginning section and the end section with undercut;Figure 8 shows a schematic representation of a method according to the invention for feeding sheet metal to a further processing unit.

[0033] In the Figures 1a to 1c Figure 10 schematically illustrates an embodiment of a system 10 according to the invention for processing sheet metal 12. The system 10 comprises a device 14 for feeding sheet metal 12 to a processing unit 16. In the illustrated embodiment, the processing unit 16 is a continuous transfer press, such as those used, for example, in the production of rotor and stator lamination stacks for electric motors. In the illustrated embodiment, the system 10 further comprises a sheet metal storage unit 18 for receiving the sheet metal and providing a buffer. The sheet metal storage unit 18 is arranged between the device 14 and the processing unit 16.

[0034] In the illustrated embodiment, the sheet metal 12 is fed into the system by means of two reels. A first sheet metal roll 20 is held in a first reel 22, and a second sheet metal roll 24 is held in a second reel 26. According to the invention, a first sheet metal roll 28 is received from the first sheet metal roll 20, and a second sheet metal roll 30 is received from the second sheet metal roll 24. The device according to the invention enables an end section of the first sheet metal roll 28 to be connected to a beginning section of the second sheet metal roll 30 when the end of the first sheet metal roll 28 or the end of the first sheet metal roll 20 is reached. By connecting the end section of the first sheet metal roll 28 to the beginning section of the second sheet metal roll 30 in the device 14 according to the invention, it is possible to continuously feed sheet metal into the downstream processing unit 16.

[0035] In the illustrated embodiment, the sheet metal storage unit 18, arranged between the device 14 and the processing unit 16, is particularly prominent. In the illustrated embodiment, this sheet metal storage unit 18 is designed as a belt storage unit with several movable deflection rollers 32. As shown in the Figures 1a to 1c As shown schematically, these deflection rollers 32 can be moved towards each other to shorten the path of the sheet 12 and empty the storage unit. It is possible that a connection is created in the device 14 between the end section of the first sheet 28 and the beginning section of the second sheet 30, and that during the creation of the connection and the associated brief interruption of the sheet feed, a continuous transfer of sheet 12 to the processing unit 16 still takes place. Figures 1a to 1c The figure shows that the first sheet 28 is used first ( Figure 1a) and then a switch to the second sheet 30 occurs when the first sheet roll 20 is used up ( Figure 1b ). In Figure 1c The diagram shows that during operation of system 10, the deflection rollers 32 are typically fully extended (moved towards each other) and therefore no buffer is provided, as the load acting on the sheet 12 is then minimal. Only shortly before the end of the second sheet 30 is reached and a switchover occurs, is the sheet storage 18 refilled by extending the deflection rollers 32 again.

[0036] It is understood that the sheet metal storage unit can also be implemented in other forms. According to the invention, a technique is provided that allows two strips to be joined together in such a way that no or only minimal idle time occurs. The sheet metal feed therefore does not need to be slowed down or stopped. This increases material utilization. This is achieved by joining the beginning of the new sheet to the end of the old sheet in such a way that the forming / stamping process is not affected. Specifically, this means that the joint created in the device 14 according to the invention can withstand the process forces, such as those caused by the strip tension, and that the seam or joint is also formable and punchable.

[0037] In particular, the use of the device or approach according to the invention is advantageous for the field of production (stamping and stacking of electrical steel sheets for electric motors).

[0038] In the Figure 2 The components of the device 14 for feeding sheet metal to a further processing unit are shown schematically. The device comprises a feeding unit 34, a dispensing unit 36, a first positioning unit 38, a second positioning unit 40, a processing unit 42, and a joining unit 44. The various units can be configured individually or in combination. In particular, a combined unit can unite or fulfill the function of two or more of the described units.

[0039] The feeding unit 34 is suitable for receiving sheet metal from coils. In particular, it can receive electrical steel sheets for rotor and / or stator lamination stacks of an electric motor. For example, the feeding unit 34 can include corresponding rollers or other mechanisms for attaching the sheets to reels.

[0040] The dispensing unit 36 ​​is designed for the continuous conveying of sheet metal to the downstream processing unit. Depending on whether buffering is possible within the device 14 or not, continuous conveying is understood to mean a supply of sheet metal to the downstream processing unit at a constant or nearly constant speed and without requiring a complete insertion and retraction of the sheet metal during sheet changes. The dispensing unit 36 ​​can be configured to use a buffer storage unit within the device 14 or to operate a sheet metal storage unit / buffer storage unit located downstream of the device 14. In the latter case, continuous dispensing means a supply to a sheet metal storage unit or buffer storage unit.This is understood as an interaction with a downstream sheet metal storage unit, whereby the continuous feed to the further processing unit results from the interaction with the sheet metal storage unit. The first fixing unit 38 and the second fixing unit 40 serve in particular to fix the beginning and end sections of the first and second sheet metal, respectively. For this purpose, the fixing units 38 and 40 can each, for example, include a hold-down device for clamping the sheet metal. Such a hold-down device presses the sheet metal onto a surface, preventing forward or backward movement and allowing processing to take place.

[0041] The processing unit 42 is designed to process the end section of the first sheet and the beginning section of the second sheet between the clamping units 38 and 40. Various tools can be used for this purpose. For example, processing can be carried out using a grinding, punching, milling, laser, plasma, waterjet, or sawing tool. By processing the end section or the beginning section, the two sections are brought into a state in which they can then be joined.

[0042] The actual connection is made using the joining unit 44. The joining unit 44 serves to create a connection that has sufficient tensile strength to enable subsequent further processing of the sheet metal in the further processing unit.

[0043] The device according to the invention enables the butt jointing of two strip-shaped sheets at their ends, creating a kind of continuous strip. The joining process is designed to be completed very quickly. Ideally, the joining process is so fast that it can be completed within a timeframe in which a suitable sheet storage unit can ensure a continuous supply to the downstream processing unit. Furthermore, the joining process allows the tension of the sheet or strip, as well as the process forces exerted by a stamping press, to be absorbed shortly after joining. The joined area can also be formed and stamped. In particular, the inventive approach ensures that no or only minimal material is added, meaning that the thickness of the sheet is not noticeably increased.Furthermore, the device and the inventive approach should not significantly alter the electrical properties, particularly in the case of electrical steel sheets.

[0044] In the Figure 3A schematic embodiment of the device according to the invention is shown in the area of ​​the first clamping unit 38 and the second clamping unit 40. In the illustrated embodiment, the two clamping units 38 and 40 are designed as hold-downs. To process the edges 46 of the first sheet 28 and the second sheet 30, the sheet ends are clamped using the hold-downs. Edge processing can then be carried out, for which, for example, a punching, milling, laser, plasma, waterjet cutting, or sawing process can be used. Any potential thermal energy input and any structural changes at the cut edges can be compensated for by a subsequent joining process. The edges 46 are prepared accordingly.

[0045] In the Figure 4It is schematically shown that after processing the end section of the first sheet and the beginning section of the second sheet in the form of the in Figure 3 The edge preparation shown, for example, involves bringing the first sheet 28 and the second sheet 30 together. Both sheets 28 and 30 remain fixed in place by means of the clamping units 38 and 40, respectively, or are re-clamped after being brought together. In particular, a zero gap is created between the two sheets 28 and 30. In other words, the end of the old sheet is first fixed across its entire width by a hold-down device. Then, the beginning of the new sheet is also fixed across its entire width at a suitable distance. The edges can then be prepared using the processing unit.

[0046] Furthermore, a technically zero gap can be achieved after the sheets are brought together. Since the quality of both sheet metal edges can vary considerably, separate processing is possible. This is carried out in the clamped, separated state and can, if necessary, be performed in parallel with two processes.

[0047] After edge preparation, the clamping unit 38, 40 can be released, for example, by raising the blank holder. The sheets can then be joined at the zero gap. Subsequently, the clamping units 38, 40 clamp again, for example, by re-raising the blank holder. Then a joint can be formed. A friction stir welding process, for example, can be used for this joint.

[0048] In the Figures 5a and 5bA friction stir welding process is shown as an example of a process for joining the machined end section with the machined beginning section. In the upper area of ​​the Figures 5a and 5b A top view is indicated. A side view is shown in the lower section, in which a weld seam 52 runs between the two sheets 28, 30.

[0049] Friction stir welding is a joining process that does not require melting the substrates. Therefore, it has a minimal impact on the electrical and mechanical properties of electrical steel. This reduces hardening, leading to improved stamping and forming properties. Furthermore, the magnetization behavior of the sheet material is only minimally affected, which can be relevant to the efficiency of an electric motor. Edge preparation is typically a prerequisite for using friction stir welding. In particular, a (technical) zero gap must be ensured for sheet thicknesses of just a few tenths of a millimeter. For this reason, the edges are first smoothed (prepared) before being fixed in place using clamping units and welded with a tool.

[0050] In this context, the Figures 5a and 5b shown that first a profiling of the edges 46 can be achieved using a rotating tool 48 or two rotating tools ( Figure 5a After the two sheets 28, 30 have been brought together, the same tool or another rotating tool 50 can be used to apply frictional heat and pressure to join the materials. For the thin sheet thicknesses used, for example, in the production of rotor and stator laminations, it is not absolutely necessary to use a friction stir welding tool with a pin. Shoulder friction welding is usually sufficient.

[0051] In friction stir welding, it is possible that the edge profiling (compare Figure 5a ) and friction stir welding (compare Figure 5b) by means of a common tool drive. However, different tools are usually, but not necessarily, used.

[0052] In the Figures 6a, 6b and 6cThis figure illustrates an approach to joining the two sheets 28 and 30 by adhesive bonding. Again, the upper part of the figure shows a top view, and the lower part a side or profile view. Adhesive bonding is particularly suitable as a cold joining method for preserving the properties of the sheet metal. Joining thin strip material in a butt joint is usually not possible. Therefore, when joining strip-shaped materials, a suitable geometry is typically created. This can often be achieved by scarfing (chamfering both sides) to increase the bonding surface. Furthermore, adhesive bonding often presents the challenge of low initial strength, as adhesives, depending on the specific system, only solidify—that is, set or cure—after several seconds or even many minutes and can consequently only be subjected to stress after this time.

[0053] According to the invention, in one embodiment it is therefore proposed that in a first step a profile is introduced into the sheet metal edges by means of the processing unit ( Figure 6aThis profile advantageously creates a positive fit. For example, hook plates known from timber construction can be used for this purpose, adapted to appropriately thin substrates. The profiling can be applied using a suitably designed machining unit. For example, a forming, grinding, or milling process, or a combination thereof, can be used. To ensure that the positive fit remains intact even under forces acting perpendicular to the impact and that the profiles do not slip apart, a second step can be performed using reactive, fast-curing adhesives (e.g., acrylates) or physically setting adhesives (e.g., hot melt adhesives) to secure the positive fit created by the profiling in the normal direction and further increase the load-bearing capacity.In this respect, the invention proposes using a positive locking mechanism that is additionally bonded to absorb normal forces and / or prevent the thin, profiled substrates from sliding apart. Figure 6b The illustration shows that adhesive is applied to the profiled edges. Figure 6c The diagram shows that the joining unit is used for assembly.

[0054] In principle, it would also be possible to use a form-fit connection, especially through an undercut, without gluing, provided that sufficient strength of the connection can be achieved through this.

[0055] In Figure 7 Four examples of possible undercut geometries are shown. The illustration in Figure 7This is to be understood in particular as a representation of the sheet metal in the area of ​​the joining point after assembly. Shown are the end section of the first sheet 28 and the beginning section of the second sheet 30. Typically, edge preparation similar to that described previously for friction stir welding and the edge profiling shown therein is required. The edges are therefore also first milled smooth or parallel before a corresponding undercut geometry can be created. The undercut geometries shown in Figure 7 These examples are not exhaustive. The undercut ensures sufficient tensile strength. The adhesive, in particular, prevents the sheets from popping out, i.e., the interlocking connection from failing.

[0056] In Figure 8A schematic representation of a method according to the invention for feeding sheet metal to a processing unit is shown. The method comprises steps S10 of receiving a first sheet and a second sheet, continuously forwarding S12 of the sheets into the processing unit, defining S14 of an initial section of the second sheet, defining S16 of an end section of the first sheet, processing S18 of the end section of the first sheet and the initial section of the second sheet, and joining S20 of the two sections. The method according to the invention can be used, in particular, as an operating method for a manufacturing plant for rotor and / or stator lamination stacks.

[0057] The invention has been comprehensively described and explained with reference to the drawings and the description. The description and explanation are to be understood as examples and not as limiting. The invention is not limited to the disclosed embodiments. Other embodiments or variations will be apparent to a person skilled in the art when using the present invention without departing from the scope of the following claims.

[0058] In the claims, the words "comprise" and "with" do not preclude the presence of further elements or steps. The undefined article "a" or "an" does not preclude the presence of multiple elements. A single element or unit can perform the functions of several of the units mentioned in the claims.

[0059] Reference numerals in the patent claims are not to be understood as restrictive.

Claims

1. A device (14) for feeding sheet metal (12, 28, 30) to a further processing unit (16), comprising: a feeding unit (34) for receiving a first sheet (28) from a first sheet coil (20) comprising wound sheet metal, and a second sheet (30) from a second sheet coil (24) comprising wound sheet metal; a delivery unit (36) for continuously forwarding sheet metal to the further processing unit; a first fixing unit (38) for fixing a beginning section of the second sheet on one side of the feeding unit when an end of the first sheet is reached; a second fixing unit (40) for fixing an end section of the first sheet on one side of the delivery unit when the end of the first sheet is reached; a processing unit (42) for processing the end section of the first sheet and the beginning section of the second sheet between the fixing units; and a joining unit (44) for joining the processed end section to the processed beginning section between the fixing units, wherein the processing unit (42) is configured to process a first side of the beginning section and an opposite second side of the end section, and to subsequently move the processed beginning section and the processed end section into an overlapping configuration, and wherein the joining unit (44) is configured to join the sheets by adhesive bonding in the region of the beginning section and the end section, characterized in that the processing unit (42) is configured to produce an interlocking profiling of the beginning section and the end section with an undercut, ensuring that the thickness of a joint region is not increased or only insignificantly increased relative to the remaining sheet.

2. The device (14) according to claim 1, wherein the joining unit (44) is configured to join the sheets by adhesive bonding using an adhesive with rapid strength development, in particular a polymerizing adhesive.

3. The device (14) according to any one of the preceding claims, wherein the first fixing unit (38) and / or the second fixing unit (40) comprises a holddown device for clamping sheet metal (12, 28, 30), preferably across an entire width of the sheet.

4. The device (14) according to any one of the preceding claims, wherein the processing unit (42) is configured to process the beginning section and the end section using a grinding, punching, milling, laser, plasma, water-jet or sawing tool; and / or the processing unit comprises a tool head movable orthogonally to a running direction of the sheet.

5. The device (14) according to any one of the preceding claims, wherein the processing unit (42) and the joining unit (44) are implemented in the form of a common tool drive using different tools (48, 50).

6. The device (14) according to any one of the preceding claims, wherein the feeding unit (34) is configured to receive the first sheet (28) from a first decoiler (22) and the second sheet (30) from a second decoiler (26).

7. A system (10) for processing sheet metal (12, 28, 30), comprising: a device (14) according to any one of the preceding claims; and a sheet metal accumulator (18) for receiving sheet metal and providing a buffer, wherein the sheet metal accumulator (18) is arranged between the device and the further processing unit (16).

8. The system (10) according to claim 7, comprising a further processing unit (16) for further processing the continuously forwarded sheet metal (12, 28, 30), wherein the further processing unit is preferably designed as a continuous transfer press and / or as a stamping tool for stamping the sheet into a predefined sheet shape.

9. The system (10) according to any one of claims 7 to 8, wherein the sheet metal accumulator (18) is designed as a loop accumulator with a plurality of movable deflection rollers (32); and the sheet metal accumulator is preferably designed to move the deflection rollers, after the joining of the end section with the beginning section has been completed, into a fully extended position in which no buffer is provided and sheet metal (12, 28, 30) is forwarded without bending.

10. A method for feeding sheet metal (12, 28, 30) to a further processing unit (16), comprising the steps of: receiving (S10) a first sheet (28) from a first sheet coil (20) comprising wound sheet metal and a second sheet (30) from a second sheet coil (24) comprising wound sheet metal by means of a feeding unit (34); continuously forwarding (S12) sheet metal to the further processing unit by means of a delivery unit (36); fixing (S14) a beginning section of the second sheet on one side of the feeding unit by means of a first fixing unit (38) when an end of the first sheet is reached; fixing (S16) an end section of the first sheet on one side of the delivery unit by means of a second fixing unit (40) when the end of the first sheet is reached; processing (S18) the end section of the first sheet and the beginning section of the second sheet by means of a processing unit (42) between the fixing units; and joining (S20) the processed end section to the processed beginning section by means of a joining unit (44) between the fixing units, wherein the step of processing comprises processing a first side of the beginning section and an opposite second side of the end section, and subsequently bringing the processed beginning section and the processed end section into an overlapping configuration, and the step of joining comprises joining the sheets by adhesive bonding in the region of the beginning section and the end section, characterized in that the step of processing comprises producing an interlocking profiling of the beginning section and the end section with an undercut, ensuring that the thickness of a joint region is not increased or only insignificantly increased relative to the remaining sheet.