Device and system for welding two ferromagnetic bodies

Abstract

Device (10) for resistance welding two ferromagnetic bodies (1; 2) which are preferably in contact with each other over their surface, comprising a base support (11), at least one electrode (14;15), at least one actuator device (16) which is fastened to the base support (11), wherein the electrode (14; 15) is attached to the actuator device (16) by means of an electrode holder (19) such that the electrode (14; 15) is movable relative to a first ferromagnetic body (1) upon actuation of the actuator device (16), and a switchable magnet (20) which is fastened to the base support (11) by means of a holding frame (22), wherein the switchable magnet (20) is arranged on the same side of the first body (1) as the actuator device (16) and can be brought into contact with the first body (1) from this side, wherein the first body (1) and the second body (2), when the magnet (20) is brought into contact with the first body (1) and actuated, are magnetically attracted to one another to form a composite by the magnetic field generated by the magnet (20), and the magnet (20) magnetically adheres to the composite formed by the first and second bodies (1; 2) in such a way that the actuator device (16) fastened to the base support (11) is positioned in a stationary position relative to the composite formed by the first and second bodies (1; 2) by magnetic attraction, so that a process force (F) can be generated by means of the actuator device (16), with which process force the electrode (14; 15) is pressed against the first body (1) during resistance welding.

Description

[0001] The invention relates to a device and a system for welding two ferromagnetic bodies that are in contact with each other.

[0002] Welding devices are known in the art for suitably fixing a strip end section of a steel strip coil to an adjacent strip winding. For example, US Pat. No. 5,705,782 A discloses a spot welding device for suitably fixing a strip end section of a steel strip coil to an adjacent strip winding by spot welding. This spot welding device comprises an elongated arm element, to the end of which a welding head with two welding electrodes is attached. A physical abutment with spherically shaped contact points is provided on the side opposite the welding electrodes. The physical abutment according to US Pat. No. 5,705,782 is designed to be movable in the radial direction of the steel strip coil.By means of a pneumatic cylinder, the physical abutment can be moved radially outwards in order to create a tension against the inner circumferential surface of the steel strip coil and thus to press the welding electrodes specifically against a strip end section of the steel strip coil that is to be welded.

[0003] WO 2020 / 249284 A1 discloses a welding device that also serves to fix a strip end section of a metal strip coil to an adjacent strip winding. In the same way as already explained for US Pat. No. 5,705,782 A, the welding device according to WO 2020 / 249284 A1 also provides a physical counterbearing in the form of a support unit, which automatically supports the friction welding device against the inner circumferential surface of the metal strip coil, thereby achieving a targeted pressing of the welding electrode in the form of a friction welding unit against the strip end section of the metal strip coil to be welded.

[0004] The aforementioned conventional welding devices according to US 5,705,782 A and WO 2020 / 249284 A1 each have the disadvantage that, to achieve the required contact force of the welding electrode, a physical counterbearing is provided. This counterbearing is arranged on the opposite side of the welding electrode and is pressed radially outward against the inner circumferential surface of the steel or metal strip coil. Such a physical counterbearing is disadvantageously associated with increased design complexity and can also be problematic due to the limited space required within the eye of a steel or metal strip coil.

[0005] According to the prior art, various welding devices are known in the field of resistance welding, for example, from DE 20 2008 013 883 U1, WO 96 / 26038 A, FR 2 837 413 A1, or US Pat. No. 2,863,985. These publications typically employ a pair of welding electrodes, which are brought into contact with two bodies to be secured together from opposite sides. In this respect, these conventional welding devices each have the disadvantage that the bodies to be secured together must be accessible from both sides, which can complicate the processing of bodies with potentially complex structures.

[0006] Accordingly, the invention is based on the object of optimizing the fixing of two ferromagnetic bodies to one another by welding with regard to the space requirement of the welding electrode used and the associated process technology.

[0007] The above object is achieved by a device having the features of claim 1, and by a system having the features of claim 10. Advantageous developments of the invention are defined in the dependent claims.

[0008] A device according to the present invention is used for resistance welding two ferromagnetic bodies that are preferably in contact with each other. This allows a first ferromagnetic body to be fixed to a second ferromagnetic body by unilateral resistance welding when the first body and the second body are in contact with each other.In detail, the device according to the invention comprises a base support, at least one electrode, at least one actuator device which is fastened to the base support, wherein the electrode is attached to the actuator device by means of an electrode holder in such a way that the electrode is movable relative to the first body upon actuation of the actuator device, and a switchable magnet which is fastened to the base support by means of a holding frame, wherein the switchable magnet is arranged on the same side of the first body as the actuator device and can be brought into contact with the first body from this side.When the magnet is brought into contact with the first body and actuated, the first body and the second body are magnetically attracted to one another to form a composite by the magnetic field generated by the magnet, the magnet magnetically adhering to the composite formed by the first and second bodies in such a way that the actuator device fastened to the base support is positioned in a stationary position relative to the composite formed by the first and second bodies by magnetic attraction force, so that a process force can be generated by means of the actuator device, with which the electrode is pressed against the first body during resistance welding.

[0009] The practical use of the device according to the invention is for the one-sided resistance welding of two ferromagnetic bodies, in which a first ferromagnetic body is brought into contact with a second ferromagnetic body, preferably over a surface area, and at least one electrode, which is attached to an actuator device fastened to a base support, is provided on one side of the first body. The switchable magnet, which is fastened to the base support, is brought into contact with the first body from the same side as the actuator device and is then actuated, so that the first body and the second body are magnetically attracted to one another by the magnetic field generated by the magnet, forming a composite, and the magnet magnetically adheres to the composite formed by the first and second bodies.As a result, the actuator device attached to the base support is positioned in a fixed position relative to the composite formed by the first and second bodies due to magnetic attraction during resistance welding. Upon actuation of the actuator device, the at least one electrode is then moved toward the first body and thus brought into contact with the first body. Upon actuation of the actuator device, a process force is generated by the actuator device, which presses the electrode against the first body during resistance welding, thereby welding the first ferromagnetic body and the second ferromagnetic body together.

[0010] For the purposes of the present invention, a ferromagnetic body is one that can be magnetized by the influence of an external magnetic field. This property of a ferromagnetic body is based on the fact that it is preferably made of a material that contains at least iron, cobalt, and / or nickel. As a result, the ferromagnetic properties of the first and second bodies according to the invention ensure that the magnet, when brought into contact with the first body and actuated, adheres or is fastened to the first body by means of the magnetic field it generates, and at the same time, when the magnet is brought into contact with the first body and actuated, the first body and the second body are magnetically attracted to one another by the magnetic field generated by the magnet to form a stable bond.

[0011] The invention is based on the essential finding that the magnet, when actuated during resistance welding, assumes the function of a magnetically acting "counterbearing" for the actuator device and the electrode attached to it. In the context of the present invention, this means that the actuator device with the electrode attached to it is or will be positioned in a fixed position relative to the composite formed by the first and second ferromagnetic bodies by means of the actuated magnet.In other words, when the switchable magnet is in contact with the composite formed by the first and second ferromagnetic bodies and is actuated, it generates a magnetic counterforce, which is then transferred to the actuator device via the base support, to which both the magnet and the actuator device are jointly attached. This counterforce positions the actuator device in its aforementioned fixed position. As a result, when the actuator device is actuated, when the electrode is moved toward the first body and contacts the surface of the first body, it is then possible to generate a required process force with which the electrode is pressed against the first body during the welding process.

[0012] Given the function of the actuated magnet as a magnetically acting abutment, with which the actuator device is positioned or held in a stationary position relative to the composite formed by the first and second ferromagnetic bodies, as explained, the invention achieves the advantage that an additional physical abutment, which is known in the prior art as an additional component above the actuator device with the electrode attached thereto for spatial fixation, is no longer required. In other words, one advantage of such one-sided resistance welding according to the invention, regardless of whether it is used with one or two electrodes, is that no complex and space-consuming physical abutment, for example in the form of counterpressure cylinders or the like, is required.Compared to such a physical abutment, as known, for example, from US Pat. No. 5,705,782 or WO 2020 / 249284 A1, the magnet used in the present invention has the advantage of being only low in height and thus requiring less space. In this regard, it should be noted again at this point that, according to the invention, the magnet is arranged relative to the first body on the same side as the actuator device with the electrode attached thereto.

[0013] In the present invention, the effect achieved with the aid of the magnet is that when the switchable magnet is in contact with the first body and is actuated, the first body and the second body are or are magnetically attracted to one another by the magnetic field generated by the magnet and thus form a stable bond together through magnetic attraction. Such a bond is to be understood in the sense of the present invention such that the first body and the second body are in contact with one another, preferably in surface contact with one another, in which the first body rests against or rests flatly on the second body. In any case, with such a bond formed from the first body and the second body, a compressive force which is exerted on the first body, for example, by the electrode, can be directly transmitted to the second body or introduced into the second body.In other words, the second body, which, as just explained, forms the aforementioned bond with the first body through the magnetic attraction of the magnetic field generated by the actuated magnet, then assumes the function of supporting the first body during the welding process on the side of the first body opposite the electrode, which is pressed against the first body with a process force. By supporting the first body in this way by means of the second body, it is possible to prevent the first body from bulging if the electrode is pressed against a first body with a comparatively small thickness (e.g., 1.5 mm) with the process force required for the welding process.

[0014] By using the second body, which together with the first body forms a stable bond by magnetic attraction as explained, and if the second body has corresponding physical properties, it is ensured according to the invention that the process force of the electrode(s) can be counteracted without accompanying deformations of the first body and that a loss of position of the actuator device to which the electrode is attached does not occur.

[0015] In connection with the above-explained support of the first body by the second body in contact therewith, it is expedient according to the invention that at least the second body has a sufficient thickness, which thus gives the composite formed from the first and second bodies by magnetic attraction sufficient stability, so that the first body can withstand an external compressive force acting on it (e.g. by the electrode).

[0016] In preparation for the planned welding process, the magnetic attraction between the first and second bodies advantageously leads to an initial fixation of these two bodies to one another, before these two bodies are then firmly joined by welding using the introduced welding current. By means of such magnetic fixation, the first and second ferromagnetic bodies form the aforementioned bond.

[0017] The present invention enables the fixing or joining of two ferromagnetic bodies of any shape by welding. In the simplest case, these two bodies can each be plate-shaped and placed on top of one another in preparation for resistance welding, so that the first and second bodies are in flat contact with one another. The actual resistance welding process for the two ferromagnetic bodies then occurs when the electrode comes into contact with the first body. The electrode is pressed against the first body with the required process force by the actuator device, and the welding current is then introduced through the electrode into the first and second bodies.

[0018] By means of the present invention, it is also possible to fix an associated strip end section of a metal strip wound into a coil with an adjacent strip winding of the coil. In this respect, an advantageous further development of the practical use of the device according to the invention consists in the first body consisting of a strip end section of a metal strip wound into a coil, wherein the second body is integrally connected to the first body and consists of a strip winding of the coil, which is arranged adjacent to the first body in the form of the strip end section. Because the magnet serves as a magnetic abutment, as already explained above, a low structural height is advantageously achieved for the actuator device used here, because a physical abutment within the eye of such a wound metal strip coil is not required.

[0019] In an advantageous development of the invention, the switchable magnet can be designed in the form of a permanent magnet, the resulting magnetic field of which, acting on the first and second bodies, can be pneumatically switched. Such a design of the magnet has the advantage that it is extremely robust and resistant to external influences, even over a long period of operation, and can also be controlled pneumatically, i.e., by supplying compressed air, in a simple and inexpensive manner.

[0020] According to an alternative advantageous development of the invention, the switchable magnet can be designed in the form of an electromagnet that can be switched by applying current. Such a magnet embodiment, like the aforementioned permanent magnet, is inexpensive and, with a view to achieving a desired long service life, robust and resistant to external influences.

[0021] In an advantageous development of the invention, at least one pole piece can be attached to an outer side of the magnet, which faces the first body, which pole piece is designed to complement a surface of the body with which the magnet can be brought into contact. In the context of the present invention, this means that the contact surface of this pole piece is adapted to the surface of the body, thus achieving good surface contact between the pole piece and the first body when the magnet is brought into contact with it.

[0022] Typically, relatively large currents are generated during resistance welding and introduced into the two bodies to be welded together. Against this background, an advantageous development of the invention is characterized in that the actuator device is attached to the base support using electrically insulating components, so that the actuator device with the electrode attached thereto is electrically insulated from the base support. As a result of such an electrically insulated attachment of the actuator device to the base support, the advantage is achieved that the aforementioned high currents are not transmitted to other components of the device according to the invention that are accommodated on or within the base support.

[0023] In an advantageous development of the invention, the actuator device can be equipped with an axially displaceable piston rod, with the electrode being attached to a free end of the piston rod by means of an electrode holder. In this case, it is expedient if the actuator device is designed in the form of a pneumatic cylinder. In any case, thanks to the axially displaceable piston rod of the actuator device, to whose free end the electrode is attached by means of an electrode holder, it is possible to generate a desired contact force for the electrode, with which it is pressed against the first body during resistance welding.

[0024] According to an advantageous development of the invention, it is possible for the aforementioned electrode holder, with which the electrode is attached to a free end of the piston rod of the actuator device, to enable replacement of the electrode as needed, for example, for maintenance and / or repair purposes. In this respect, the electrode holder is designed in such a way that it allows for easy replacement of the electrode at the free end of the piston rod.

[0025] A system according to the invention, which has independent significance, also serves for resistance welding two ferromagnetic bodies that are preferably in surface contact with one another. Specifically, such a system comprises a robot arm having a plurality of degrees of freedom and / or a plurality of arm elements with a plurality of pivot joints with resulting degrees of freedom. Preferably, a robot arm is designed in the form of an industrial robot with at least two degrees of freedom and has two or more articulated arms, each of which is pivotable about a vertical or horizontal axis of rotation. Furthermore, the system according to the invention also comprises a device according to the present invention, which has already been described and explained above. In this case, the base support of this device according to the invention can then be attached to a free end of the robot arm or adjacent thereto.

[0026] According to an advantageous development of the system according to the invention, a support table is also used, which is arranged at a predetermined position and on which the device can be placed with its base support. For this purpose, complementary centering means are provided on the support table and on the base support of the device, which are attached to the support table at predetermined positions. These centering means can expediently be formed from centering pins on the one hand and centering sleeves on the other, with a respective opening of a centering sleeve being adapted to the outer diameter of an associated centering pin.If, for example, the centering pins are attached to the support table, with the centering sleeves being attached to the base support, the base support can be placed in a predetermined position from above on the support table by the centering sleeves self-centeringly receiving the centering pins located underneath from above.

[0027] According to an advantageous development of the invention, the first ferromagnetic body can have a thickness of up to 5 mm at the point where it is in contact with the second ferromagnetic body. In other words, according to the present invention, it is possible for the first body to have a maximum thickness of 5 mm at its contact point with the second body. Alternatively, the first body can also have a thickness of less than 5 mm at its contact point with the second body, for example up to 4 mm, more preferably up to 3 mm, more preferably up to 2 mm, more preferably up to 1.5 mm, and more preferably up to 1 mm.At this point, it should be specifically noted that, particularly when the thickness of the first body is less than 5 mm, sufficient stability when the electrode is pressed against the first body with a process force required for welding is ensured by the first body being in contact with the second body, with the second body being located on the opposite side of the first body compared to the electrode. Furthermore, the first body and the second body are attracted to one another by the magnetic force generated by the magnet, as explained, whereby the contact between the first body and the second body is intensified and, as already explained, a stable bond is formed between these two bodies.In concrete terms, this means that for a possible design of the first body in the form of a plate with a thickness of only 1.5 mm, thanks to the contact of this plate with the second body adjacent to it, which adheres to it by magnetic force, any bending or deformation of this plate when the electrode is pressed against it is effectively prevented and is therefore not possible.

[0028] The present invention is preferably suitable for single-sided resistance welding, in which at least one electrode is brought into contact with the composite formed by the first and second bodies from one side only, wherein the introduction of a welding current then results in welding of the first body to a second body in contact therewith, which is located on the opposite side of the first body to the electrode.

[0029] According to an alternative embodiment of the present invention, a different one-sided welding principle can also be used, for example, friction welding or a welding process in which the electrode is consumed or additional weld metal is added. In accordance with such an alternative welding principle, the electrode used according to the invention is then adapted accordingly. The above-explained mode of operation of the magnetic abutment, which is realized for the actuator device and the electrode attached thereto by actuating the magnet, remains unchanged even with such an alternative welding principle.

[0030] The invention is schematically illustrated below using preferred embodiments in the drawing and is described in detail with reference to the drawing. In the drawings: Fig. 1 a side view of a part of a device according to the invention in a basic position, Fig. 2 a side view of the device of Fig. 1 in an operating position, Fig. 3 is a side view of an actuator device which is part of the device of Fig. 1 or Fig. 2 and to which an electrode is attached by means of an electrode holder, Fig. 4 a perspective view of two actuator devices forming part of the device of Fig. 1 or Fig. 2 are, Fig. 5 a perspective view from below of the two actuator devices of Fig. 4, Fig. 6 a perspective view of the device according to the invention of Fig. 1 from diagonally above, Fig. 7 a perspective view of the device according to the invention of Fig. 6 from diagonally below, Fig. 8 a perspective view of the device according to the invention of Fig. 6 from diagonally below, Fig. 9 is a front view of a magnet and pole pieces attached thereto, which are part of the device according to the invention of Fig. 1 are, Fig. 10 a front view of the magnet and the pole pieces attached to it from Fig. 9, when the pole pieces are brought into contact with a first body, Fig. 11 is a cross-sectional view of a portion of the base support of the device of Fig. 1 and an actuator device attached thereto, Fig. 12 is a perspective view of part of the base support of the device according to the invention of Fig. 1 and an attached subframe for holding the magnet of Fig. 9, Fig. 13 is a perspective view of part of the base support of the device according to the invention of Fig. 1, Fig. 14 a perspective view of the magnet of Fig. 9, the part of the device according to the invention of Fig. 1 is, Fig. 15 is a perspective view of a transformer forming part of the device according to the invention of Fig. 1 is, Fig. 16 a perspective view of a marking head in a first operating position, Fig. 17 a perspective view of the signing head of Fig. 16 in a second operating position, Fig. 18 a perspective view of an industrial articulated robot arm with a plurality of degrees of freedom, Fig. 19 a perspective view of the robot arm of Fig. 18, with the signing head of Fig. 16 is mounted, Fig. 20 a perspective view of a system according to the invention consisting of the robot arm according to Fig. 19, the signing head mounted on it from Fig. 16 and the device according to the invention of Fig. 1 exists, Fig. 21 a perspective view of a storage table and a device that can be placed thereon from Fig. 1, each of which is part of the system according to the invention of Fig. 20 are, Fig. 22 a perspective view of the storage table and the device of Fig. 21, when the device is placed on the support table, Fig. 23 a perspective view of the storage table of Fig. 21 respectively Fig. 22, Fig. 24 Details of centering devices used to fix the storage table of Fig. 23 is equipped, and Fig. 25 a perspective view of a part of the storage table and a device according to Fig. 21, to allow the device to be placed on the centering means of the support table according to Fig. 24 to illustrate.

[0031] Below, with reference to the Fig. 1-25 illustrate and explain preferred embodiments of a device 10 according to the invention and a corresponding system 40, with which a first ferromagnetic body 1 can be fixed to a second ferromagnetic body 2 by single-sided resistance welding. Identical features in the drawings are provided with identical reference numerals. It is specifically noted at this point that the drawing is merely simplified and, in particular, is not drawn to scale.

[0032] At this point, it is specifically noted that the two bodies 1, 2 that are welded together according to the invention always have ferromagnetic properties, for which reference is made to the explanation in the introduction to the description. Even though the first body 1 and the second body 2 are referred to as such below for the sake of simplicity, it should nevertheless be understood according to the invention that these bodies 1, 2 are each ferromagnetic, as explained above.

[0033] Fig. Figure 1 shows a side view of a portion of the device 10 according to the invention, which serves for resistance welding the two ferromagnetic bodies 1, 2 that are in contact with each other. The device 10 comprises a base support 11, on whose first end face 12 at least one actuator device 16 (cf. Fig. 3). The fastening of the actuator device 16 to the first end face 12 of the base support 11 will be explained separately below.

[0034] The device 10 according to the invention comprises at least one electrode 14, 15, which is attached to the actuator device 12 by means of an electrode holder 19.

[0035] The device 10 according to the invention further comprises a switchable magnet 20, which is attached to the base support 11 by means of a holding frame 22. The side view of Fig. Figure 1 illustrates that the holding frame 22 is also attached to the first end face 12 of the base support 11 of the device 10 according to the invention. The holding frame 22 serves the purpose of holding the switchable magnet 20 on the base support 11 adjacent to the electrode 14, 15.

[0036] The switchable magnet 20 is in the Fig. 14 in a perspective view. In the embodiment shown here, the switchable magnet 20 can be in the form of a permanent magnet which can be switched pneumatically, i.e. by means of a supply of compressed air. Such switching of the permanent magnet 20 is to be understood according to the invention such that the resulting magnetic field, which acts from this magnet 20 on the side which can be brought into contact with the first body, can be switched pneumatically, i.e. is switched on or off. If the permanent magnet 20 is switched on, this is also referred to according to the invention as an "actuated magnet", so that the magnetic field of the permanent magnet 20 acts on the first ferromagnetic body 1 and thus a magnetic attraction occurs between the magnet 20 and the first body 1 in contact with it.In the same way, the magnetic field emanating from the magnet 20 also acts on the second body 2, such that the first and second bodies 1, 2 form a stable bond through magnetic attraction. This bond is characterized by its ability to withstand a compressive force applied to the first body 1 from the outside, for example, by the electrodes 14, 15.

[0037] In the Fig. 14 are for the permanent magnet 20 the necessary lines for the supply of compressed air are not shown for simplification.

[0038] Alternatively to displaying Fig. 14, the switchable magnet 20 can also be designed in the form of an electromagnet that can be switched by energization.

[0039] For further illustration of the actuator device 16, this is shown in the Fig. 3 in a side view. Details of this actuator device 16 will be discussed in more detail below.

[0040] For further illustration of the device 10 according to the invention, this is shown in the Fig. 6, Fig. 7 and Fig. 8 are shown in perspective. This shows that within the base support 11 a transformer 24, which is also shown in the Fig. 15 is shown in perspective. Power cables 26 lead from the transformer 24 (cf. Fig. 7, Fig. 8, Fig. 15) to the respective electrodes 14, 15. Through these power cables 26, the electrodes 14, 15 are supplied with the required welding current by the transformer 24.

[0041] To protect the transformer, a cover plate 25 (see Fig. 6, Fig. 15) may be appropriate.

[0042] Pole shoes 28 are attached to an underside of the magnet 20. These pole shoes are shown in the respective perspective views according to the Fig. 6 - 8, and also again in the side view of Fig. 9. These pole shoes 28 serve the purpose of bringing the magnet 20 into contact with a first body 1. The shape of the pole shoes 28 is complementary to a surface of the first body 1 with which the magnet 20 can be brought into contact.

[0043] If the first body 1 is plate-shaped and flat, a pole piece 28 of the magnet 20 is correspondingly designed with a flat or level contact surface. As a result, good surface contact is achieved between the pole pieces 28 and the surface of the first body 1 when the magnet 20, with its attached pole pieces 28, is placed on the first body 1.

[0044] By means of the present invention, it is also possible to process a first body 1 and a second body 2 that have a non-planar structure. This can be the case, for example, with a metal strip wound into a coil. In this case, the first body 1 consists of a strip end section of the metal strip coil, wherein the second body 2 is integrally connected to the first body 1 and consists of a strip winding of the metal strip coil, which is arranged adjacent to the first body 1 in the form of the strip end section. Fig. 10, the first body 1 is shown in the form of the said strip end section of a metal strip coil (not shown in its entirety for the sake of simplicity) and the second body 2 is shown in the form of an adjacent strip winding of the metal strip coil.

[0045] The side view of Fig. Fig. 9 illustrates an embodiment of the pole shoes 28 attached to an underside of the magnet 20, which with their shape in relation to a surface of the first body 1 in the form of a strip end section of a wound metal strip coil according to Fig. 10 are complementary. This means that the pole shoes 28 of the magnet 20 according to the embodiment of Fig. 9 then, as in the side view of Fig. 10, can be placed within the eye of a wound metal strip coil onto the first body 1 in the form of an associated strip end section of the metal strip coil.

[0046] Fig. 1 shows the device 10 according to the invention in a basic position when the magnet 20 fastened to the first end face 12 of the base support 11 with its pole pieces 28 is in contact with a first body 1.

[0047] In the side view of Fig. 1, the first body 1 and the second body 2 are shown in a simplified manner, for example in the form of plate-shaped elements. Likewise, from the view of Fig. 1 that the first body 1 and the second body 2 are in contact with each other, with the second body 2 being arranged on an opposite side of the first body 1 compared to the magnet 20. As a result, it is possible for the magnet 20 and the pole pieces 28 attached thereto to come into contact only with a surface of the first body 1, but not directly with the second body 2.

[0048] The actuator device 16 is provided with an axially displaceable piston rod 17 (cf. Fig. 3) equipped. According to the presentation of Fig. 3, an electrode 14 is attached to a free end of the piston rod 17 by means of an electrode holder 19.

[0049] According to an embodiment of the device 10 according to the invention, the actuator device 16 can be Fig. 3 may be designed in the form of a pneumatic cylinder. In any case, upon actuation of such an actuator device 16, the associated piston rod 17 can be extended in the axial direction with a predetermined force F.

[0050] For fastening an actuator device 16 to the first end face 12 of the base support 11, a fastening block 18 is formed on an outer circumferential surface of the actuator device 16, in which - as can be seen from the perspective view of Fig. 4 - two threaded holes G are formed in each case.

[0051] In association with the threaded holes G formed in the fastening block 18 of an actuator device 16, a plate P (cf. Fig. 12), which is provided on the first end face 12 of the base support 11, through holes are formed through which fastening screws S (cf. Fig. 11) and screwed with their free ends into the said threaded holes G.

[0052] According to the embodiment of Fig. 4, two actuator devices 16 can be provided for the device 10 according to the invention, on which - as shown in the illustration of Fig. 5 - each with a separate electrode 14, 15 by means of an electrode holder 19. In correspondence to these two actuator devices 16 according to the Fig. 4 and Fig. 5 are in perspective view according to Fig. 12 a total of four screw heads S can be seen, ie two fastening screws S per actuator device 16.

[0053] The device 10 according to the invention is shown in Fig. 1 is shown in a basic position. According to the invention, this basic position is to be understood to mean that there is no contact between the electrode(s) 14 / 15 and a surface of the first body 1, and that the magnet 20 is not yet switched or actuated.

[0054] The invention now works as follows: In preparation for a welding process planned for the first body 1 and the second body 2, the device 10 is first brought close to the first body 1 such that the magnet 20 with the pole pieces 28 attached thereto comes into contact with a surface of the first body 1. This then corresponds to the already mentioned basic position for the device 10 according to the invention. In this case, the magnet 20 is located on the same side of the first body 1 as the actuator device 16 with the electrode 14 / 15 attached thereto, which, however, is still spaced apart from the first body 1 (cf. Fig. 1). The magnet 20 is then switched or actuated, so that the magnetic field generated by the magnet 20 creates a magnetic attraction between the magnet 20 and the first body 1. A magnetic force acts from the magnet 20 on the first ferromagnetic body 1, attracting the magnet 1 to the first body 1. At the same time, the magnetic field emanating from the magnet 20 acts on the first body 1 and the second body 2, such that the first body 1 and the second body 2 form a stable bond through magnetic attraction, which can absorb an external compressive force.To generate the required process force F for the welding process, the actuator device 16 is then actuated, whereby the electrode 14 / 15 attached to it is moved in the direction of the stable composite formed by the first and second bodies 1, 2 through magnetic attraction by means of a displacement of its piston rod 17. After the electrode 14 / 15 touches the first body 1, the desired process force F increases and is reached, because the magnet 20 is held to the stable composite formed by the first and second bodies 1, 2 through the magnetic attraction force, thus forming a "magnetic abutment," and because the actuator device 16 is attached, as explained, to the first end face 12 of the base support 11 of the device 10, in the same way as the magnet 20.

[0055] The magnetic field generated by the magnet 20 leads to two effects, namely: (i) The first body 1 and the second body 2, both of which have ferromagnetic properties, are magnetically attracted to each other by the magnetic field generated by the magnet 20 in contact with the first body 1. As a result, these two bodies 1, 2 form a stable composite that can withstand an external compressive force applied to the first body 1. (ii) The actuator device 16 is positioned in a fixed position relative to the composite formed by the first and second bodies 1, 2 by attracting the magnet 20 and the composite formed by the first and second bodies 1, 2 to each other by magnetic attraction. The magnetic counterforce thus generated by the magnet 20 is transferred to the actuator device 16 because both the magnet 20 and the actuator device 16 are each attached to the base support 11, as explained.

[0056] Based on the fact that, as explained, upon actuation of the magnet 20, the actuator device 16 has been positioned in a fixed position by means of magnetic attraction force relative to the composite formed by the first and second bodies 1, 2 by magnetic attraction force, it is now possible, upon actuation of the actuator device 16, to press the electrode 14 / 15 with a predetermined process force F against the first body 1, whereby the electrode 14 / 15 comes into contact with the first body 1. This is shown in the side view of Fig. 2. As soon as the electrode 14 / 15 has come into contact with a surface of the first body 1 and the required process force F has been applied to the electrode 14 / 15, the required welding current flows through the power cable 26 to the electrode 14 / 15, resulting in resistance welding of the first body 1 to the second body 2.

[0057] According to the invention, the switchable magnet 20, when in contact with the first body 1 and suitably actuated in preparation for the welding process, serves as a "magnetic abutment." In the context of the present invention, this means that thanks to the actuated magnet 20, which is attached to the first end face 12 of the base support 11 of the device 10 in the same way as the actuator device, the actuator device 16 is positioned in a fixed position by means of magnetic attraction relative to the composite formed by the first body and the second body by magnetic attraction. As a result, it is then possible, as explained, for the actuator device 16 to generate the required process force F with which the electrode 14 / 15 is pressed against the first body 1 during resistance welding (cf. Fig. 2).

[0058] According to a possible embodiment of the device 10 according to the invention, it can be equipped with only one electrode 14, which, as explained, is attached to an associated actuator device 16 on its axially displaceable piston rod 17 by means of an electrode holder 19 (cf. Fig. 3). If, in such an embodiment, resistance welding is provided or carried out by means of the electrode 14 to connect the first body 1 to the second body 2, then when the welding current is introduced through the electrode 14, the circuit is closed by a mass M (to be understood in the sense of electrical engineering) which is connected to the second body 2 (cf. Fig. 3) can be created.

[0059] The representation according to the Fig. 3 further illustrates that a thickness of the second body 2 can be greater than a thickness d of the first body 1 (cf. Fig. 2).

[0060] As an alternative to just a single electrode, a possible further embodiment for the device 10 according to the invention can also be equipped with two electrodes 14 / 15 (cf. Fig. 4, Fig. 5), which are attached to respective associated actuator devices 16 and their piston rods 17. In the case of such an embodiment with two electrodes 14, 15, a separate mass M (to be understood in the sense of electrical engineering), which was described above in connection with the embodiment of Fig. 3 is not necessary because the circuit for the required welding current is formed between the two electrodes 14, 15.

[0061] The fastening of an actuator device 16 to the first end face 12 of the base support 11 of the device 10 is expediently carried out in an electrically insulating manner. To achieve this, electrically insulating components are used, for example in the form of an electrically insulating plate 30, an electrically insulating sleeve 31, and an electrically insulating washer 32, wherein these components are shown in the cross-sectional view of Fig. 11. In any case, these electrically insulating components 30, 31, 32 are used in conjunction with the fastening screw S, which, as already explained, is screwed into an associated threaded hole G formed in the fastening block 18 of the actuator device 16 for fastening an actuator device 16 to the first end face 12 of the base support 11. As a result, an electrically insulated fastening of the actuator device 16 relative to the base support 11 is achieved, so that the comparatively high welding currents supplied to the electrode(s) 14 / 15 by the power cables 26 cannot be conducted back into the base support 11.

[0062] As already explained above, an actuator device 16 can be designed in the form of a pneumatic cylinder. Accordingly, compressed air lines L (cf. Fig. 12) are provided, which are guided through the plate P on the first end face 12 of the base support 11.

[0063] The present invention is suitable for processing a first and second ferromagnetic body and joining them by welding. It is advantageous if the first body 1 has a maximum thickness d of 5 mm at the point where it is in contact with the second body 2. In this regard, reference is again made to the schematically simplified side view of Fig. 2, in which a thickness d is indicated for the first body 1.

[0064] According to an alternative use of the device according to the invention, for resistance welding the two magnetic bodies 1, 2 mentioned, it can also be provided that the first body 1 has a thickness of less than 5 mm, for example a thickness of up to 4 mm or possibly even less, more preferably a thickness d of a maximum of 1 mm. Within the meaning of the present invention, it is also possible for the first body 1 to have a thickness d that can have any value within the range between 1 mm and 5 mm.

[0065] With reference to the illustration in the Fig. 3 and the second body 2 mentioned therein, it should be specifically pointed out at this point that a thickness of this second body 2 can be considerably greater than that of the first body 1. It is only important for the above-mentioned functioning of the present invention that both of these bodies 1, 2 are ferromagnetic, so that by means of the magnetic field generated by the actuated magnet 20, these two bodies 1, 2 are attracted to one another and then form a stable bond with one another by means of magnetic attraction.

[0066] According to an advantageous development of the invention, the device 10 can be equipped with a marking head 34 which is Fig. 16 is shown in a simplified perspective view.

[0067] In order to connect the marking head 34 to the base support 11, the device 10 is equipped with a coupling device 39 which is arranged both on a side surface of the marking head 34 and on a second end face 13 of the base support (cf. Fig. 13). By means of this coupling device 39, the marking head 34 can be attached to the second end face 13 of the base support 11 of the device 10 and, if necessary, can also be removed therefrom again.

[0068] With reference to the perspective view of Fig. 6, it should be specifically noted at this point that the two end faces 12, 13 of the base support 11 are provided on opposite sides thereof. Specifically, this means that the marking head 34 can be mounted on the base support 11 on an opposite end face of the base support 11 compared to the holding frame 22 with the switchable magnet 20.

[0069] The signing head 34 comprises a housing 35 in which a camera device 36 (cf. Fig. 17). The housing 35 is provided with a movable flap 38 (cf. Fig. 16) with which the camera device 16 can be shielded from the environment. This state is shown in the perspective view of Fig. 16. In contrast, the movable flap 38 can be moved into an open position (cf. Fig. 17), in which the optics of the camera device 36 are exposed to the surroundings.

[0070] In the event that the marking head 34 is attached to the base support 11 of the device 10 by means of the coupling device 39 as explained, it is possible, in preparation for the planned welding process, for the first and second bodies 1, 2 to be suitably detected or scanned by means of the camera device 36 of the marking head 34 in order to record the exact spatial position of these two bodies 1, 2 and then to bring the device 10 according to the invention into position accordingly, as is the case, for example, in Fig. 1, in which the pole shoes 28 of the magnet 20 are brought into contact with the first body 1. In this context, it is understood that during such detection or scanning of the first and second bodies 1, 2, the movable flap 38 is in its open position, as shown in the Fig. 17 is shown.

[0071] If the marking head 34 is mounted on the base support 11 of the device 10, but the use of the camera device 36 is not or no longer required, the movable flap 38 of the marking head 34 is expediently moved into the closed position, as shown in the Fig. 16. As a result, the optics of the camera device 36 are then suitably shielded from the environment by the closed flap 38 and thus protected.

[0072] Below, with reference to the Fig. 18 - 25 Features of a system 40 according to the invention are shown and explained in detail.

[0073] A system 40 according to the invention also serves for resistance welding two ferromagnetic bodies 1, 2 which are in contact with each other.

[0074] The system 40 according to the invention uses a robot arm 42 which has a plurality of degrees of freedom and / or a plurality of arm elements with a plurality of pivot joints with resulting degrees of freedom. Such a robot arm 42 is schematically simplified in the perspective views according to the Fig. 18, Fig. 19 and Fig. 20 shown.

[0075] A marking device W can be attached to a free end 43 of the robot arm 42, which will be discussed separately below. According to the presentation of Fig. 19, the signing head 34 can be attached to the free end 43 of the robot arm 42.

[0076] Furthermore, according to the perspective view of Fig. 20, it is also possible to attach the device 10 according to the invention already explained above to the free end 43 of the robot arm 42. This can, as shown in the Fig. 20, with the interposition of the marking head 34. Specifically, this means that the marking head 34 is then first attached to the free end 43 of the robot arm 42, and then, using the coupling device 39, the device 10 with its base support 11 is also attached to the marking head 34.

[0077] Alternatively to displaying Fig. 20, it is also possible according to the invention to mount the device 10 directly on the free end 32 of the robot arm 42 without the marking head 34 being used.

[0078] When using the system 40 according to the invention, it is possible for the two bodies 1, 2 to be joined to first be suitably scanned with the aid of the robot arm 42 and for their spatial position to be recorded, wherein initially only the marking head 34 can be attached to the free end 43 of the robot arm 42. This means that spatial recording of the two bodies 1, 2 is initially only carried out by the marking head 34 attached to the free end 43 of the robot arm 42, without the device 10 with its base support 11 being mounted on the marking head 34. This can be achieved according to the invention with the aid of a storage table 44 (cf. Fig. 21, Fig. 22) on which the device 10 is “parked”.

[0079] Using the aforementioned support table 44, the device 10 according to the invention can be set down or "parked" when it is not mounted on the free end 43 of the robot arm 42. For this purpose, respective centering means are provided on both the support table 44 and the base support 11 of the device 10. Specifically, these centering means include centering pins 45, which, as shown in the Fig. 21, Fig. 23 and Fig. 24 are attached to the edge areas of the storage table 44, as well as centering sleeves 46, which are shown in the Fig. 6, Fig. 21 and Fig. 25 are attached to an underside of the base support 11.

[0080] A summary of the Fig. 21, Fig. 22 and Fig. 25 illustrates that when the device 10 according to the invention is placed or “parked” from above on the support table 44, the centering sleeves 46 are placed from above on the centering pins 45, wherein the centering sleeves 46 are positioned in a self-centering manner on the centering pins 45.

[0081] With regard to the support table 44, it is specifically noted at this point that for the intended use of the present invention, this support table 44 is located at a predetermined position. This ensures that the device 10 according to the invention, when coupled to the free end 43 of the robot arm 42, is always started or picked up from a precisely predetermined or known position, and the subsequent welding process for joining the two bodies 1, 2 can be carried out with high reliability.

[0082] A cleaning brush 48 (cf. Fig. 23). This cleaning brush 48 serves to clean the magnet 20 with its attached pole shoes 28. Such cleaning can be carried out in such a way that, when the device 10 according to the invention is mounted on the robot arm 42, the robot arm 42 is moved in such a way that the magnet 20 with its underside and the attached pole shoes 28 are moved past the cleaning brush 48, so that any dirt that may adhere to the underside of the magnet 20 and the attached pole shoes 28 is removed.

[0083] According to the invention, the aforementioned cleaning of the magnet 20 and the pole pieces 28 attached thereto with the cleaning brush 48 can be carried out before and / or after performing a welding process of the two bodies 1, 2. This leads to the advantage that, during a subsequent welding process, a "clean" contact of the pole pieces 28 on or at the surface of the first body 1 is ensured, thereby improving the quality of the welding process.

[0084] With regard to the aforementioned cleaning brush 48, it should additionally be noted that it can, for example, be driven in rotation about a vertical axis. If the magnet 20, with its underside and the pole pieces 28 attached thereto, is brought into contact with the cleaning brush 48 for cleaning purposes, the desired cleaning effect can be improved by rotating the cleaning brush 48 about its axis of rotation. At the same time, by rotating the cleaning brush 48 about its axis of rotation, when the magnet 20 with the pole pieces 28 attached thereto is no longer in contact with the cleaning brush 48, self-cleaning of this cleaning brush 48 can also be achieved if it is rotated about its axis at a high angular velocity.Such self-cleaning of the cleaning brush 48 can be achieved additionally or alternatively by a scraper plate (not shown) which is attached to the storage table 44 adjacent to the cleaning brush 48.

[0085] The present invention can also be equipped with a marking device W, by means of which an inscription can be produced on the first body 1 and / or on the second body 2, for example by using laser technology. Such a marking device W can be attached to the free end 43 of the robot arm 42 and is accordingly Fig. 18 and Fig. 19, here designated "W." If the first body 1 and the second body 2 have been suitably measured or recorded with respect to their spatial arrangement or positioning by the use of the marking head 34, an inscription can then be produced on the first body 1 and / or on the second body 2 by means of the marking device W, with a view to handling these bodies 1, 2 in a subsequent processing step.

[0086] If, by means of the above-mentioned inventive system 40, a strip end section of a wound metal strip coil is welded to or with an adjacent strip winding of the metal strip coil, this has the advantage that the inventive device 10, when mounted on the free end 43 of the robot arm, can then be fully automatically inserted into the eye or interior of the metal strip coil by means of the robot arm 42. This is particularly advantageous when processing hot strips. In this context, it should also be noted that such a metal strip coil has ferromagnetic properties, thus ensuring that the actuated magnet 20 adheres to the first body 1 in the form of the strip end section of the wound metal strip coil.

[0087] It should be added that the above-explained composite formed by the first and second bodies by magnetic force, in the case of a wound metal strip coil, specifically consists of the associated strip end section (= first body 1) and an adjacent strip winding (= second body 2) of the metal strip coil, preferably a plurality of such strip windings. If, in the case of a metal strip coil, the strip end section rests against the adjacent strip winding and the strip winding located underneath is then magnetically attracted to the strip end section by the magnetic field generated by the magnet 20, the strip end section is sufficiently supported by the strip winding located underneath. This prevents the strip end section from bulging when the electrode 14, 15 is pressed against it with the process force F required for resistance welding.

[0088] Finally, it is pointed out that an electrode holder 19 (cf. Fig. 3, Fig. 4, Fig. 5), by means of which an electrode 14 / 15 is connected to an associated actuator device 16, can be equipped with water cooling. For example, such an electrode holder 19 can be designed in the form of a copper block in which at least one cooling water channel, or possibly several such cooling water channels, can be formed. In any case, such water cooling of the electrode holder 19 achieves the advantage that comparatively high temperatures that arise on the electrode(s) 14 / 15 during a welding process are then not transferred to the adjacent actuator device 16. List of reference symbols 1 First ferromagnetic body 2 Second ferromagnetic body 10 Device 11 base supports 12 First end face (of the base support 11) 13 Second end face (of the base support 11) 14 Electrode 15 Electrode 16 Actuator device 17 Axially movable piston rod (of the actuator device 16) 18 Mounting block (of the actuator device 16) 19 Electrode holder 20 Switchable magnet 22 holding frames 24 Transformer 25 cover plate 26 power cables 28 Pole piece 30 Electrically insulating plate 31 Electrically insulating sleeve 32 Electrically insulating washer 34 Signing head 35 Housing (of the marking head) 36 Camera setup 38 Movable flap 39 Coupling device 40 systems 42 Robot arm 43 Free end of the robot arm 44 storage table 45 Centering pin (e) 46 centering sleeve(s) 48 Cleaning brush d Thickness (d) (of the first body 1) F Process force (for electrode(s) 14, 15) G threaded hole M Mass (electrical engineering) P plate S fixing screw W Marking device QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] US 5,705,782 A [0002, 0003, 0004] US 5,705,782 [0002, 0012] WO 2020 / 249284 A1 [0003, 0004, 0012] DE 20 2008 013 883 U1

[0005] WO 96 / 26038 A

[0005] FR 2 837 413 A1

[0005] US 2,863,985

[0005]

Claims

[1] Device (10) for resistance welding two ferromagnetic bodies (1; 2) which are preferably in contact with each other over their surface, comprising a base support (11), at least one electrode (14;15), at least one actuator device (16) which is fastened to the base support (11), wherein the electrode (14; 15) is attached to the actuator device (16) by means of an electrode holder (19) such that the electrode (14; 15) is movable relative to a first ferromagnetic body (1) upon actuation of the actuator device (16), and a switchable magnet (20) which is fastened to the base support (11) by means of a holding frame (22), wherein the switchable magnet (20) is arranged on the same side of the first body (1) as the actuator device (16) and can be brought into contact with the first body (1) from this side, wherein the first body (1) and the second body (2), when the magnet (20) is brought into contact with the first body (1) and actuated, are magnetically attracted to one another to form a composite by the magnetic field generated by the magnet (20), and the magnet (20) magnetically adheres to the composite formed by the first and second bodies (1; 2) in such a way that the actuator device (16) fastened to the base support (11) is positioned in a stationary position relative to the composite formed by the first and second bodies (1; 2) by magnetic attraction, so that a process force (F) can be generated by means of the actuator device (16), with which process force the electrode (14; 15) is pressed against the first body (1) during resistance welding. [2] Device (10) according to claim 1, characterized bythat the switchable magnet (20) is designed in the form of a permanent magnet, wherein the resulting magnetic force of the permanent magnet is pneumatically switchable. [3] Device (10) according to claim 1 or 2, characterized by that the switchable magnet (20) is designed in the form of an electromagnet which can be switched by energization. [4] Device (10) according to one of the preceding claims, characterized by that on an outer side of the magnet (20) which faces the first body (1), at least one pole shoe (28) is attached, which is designed to be complementary to a surface of the first body (1) with which the magnet (20) can be brought into contact. [5] Device (10) according to one of the preceding claims, characterized bythat the actuator device (16) is attached to the base support (11) using electrically insulating components (30; 31; 32) so that the actuator device (16) is electrically insulated from the base support (11). [6] Device (10) according to one of the preceding claims, characterized by that the actuator device (16) is equipped with an axially displaceable piston rod (17), wherein the electrode (14; 15) is attached to a free end of the piston rod (17) by means of an electrode holder (19), preferably that the actuator device (16) is designed in the form of a pneumatic cylinder. [7] Device (10) according to one of the preceding claims, characterized bythat a marking head (34) with a camera device (36) is attached to the base support (11), with which the first body (1) and / or the second body (2) can be detected before the resistance welding is carried out, preferably that the magnet (20) is attached to a first end face (12) of the base support (11) and the marking head (34) is attached to an opposite second end face (13) of the base support (11), further preferably that a coupling device (39) is provided on each of the base support (11) and on the marking head (34), with which coupling device the base support (11) can be connected to the marking head (34). [8] Device (10) according to claim 7, characterized by a marking device (W) by means of which an inscription can be produced on the first body (1) and / or on the second body (2). [9] Device (10) according to claim 7 or 8, characterized bythat the camera device (36) and its associated optics are accommodated within a housing of the signing head (34) and can be shielded from the environment by a movable flap (38) or the like. [10] System for resistance welding two ferromagnetic bodies (1; 2) which are preferably in contact with each other, comprising a robot arm (42) having a plurality of degrees of freedom and / or a plurality of arm elements with a plurality of pivot joints with resulting degrees of freedom, preferably in that a robot arm (42) is designed in the form of an industrial robot with at least two degrees of freedom and has two or more articulated arms, each of which is pivotable about a vertical or horizontal axis of rotation, and a device (10) according to any one of claims 1 to 9, wherein the base support (11) of the device (10) is attached to a free end of the robot arm (42) or adjacent thereto. [11] System according to claim 10, characterized by a support table (44) arranged at a predetermined position, on which the device (10) with its base support (11) can be placed, wherein centering means (45; 46) which are each designed to be complementary to one another are provided on the support table (44) and on the base support (11) of the device (10), which are attached to the support table (44) at predetermined positions, preferably that the centering means are designed on the one hand from centering pins (45) and on the other hand from centering sleeves (46), wherein the centering pins (45) and the centering sleeves (46) are adapted to one another in a complementary manner, so that the centering pins (45) can be at least partially received in the centering sleeves (46).

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