METHOD FOR MANUFACTURING A MAGNETICALLY SEPARATED CORE TUBE AND MAGNETIC ACTUATOR DEVICE WITH THE CORE TUBE

Description

State of the art

[0001] The invention relates to a method according to the preamble of claim 1, a magnetic actuator device according to the preamble of claim 11 and a magnetic actuator according to claim 16.

[0002] It has already been proposed that core tubes be provided with a pressure-tight magnetic separation. Currently, this separation is achieved through welding processes, such as cladding or capacitor discharge welding, or through brazing processes, such as MIG brazing or hard brazing, whereby a (ring-shaped) separating element made of a non-magnetic material is inserted into the core tube. All previously used methods expose the core tube to high temperatures. This damages or destroys the delicate conical geometries at the interface between the magnetic core tube body and the non-magnetic separating element, for example, through partial melting. Consequently, significant and costly technical effort has been invested in the execution, control, and / or monitoring of the welding or brazing processes used to minimize damage to the conical geometry.

[0003] Furthermore, the described welding or soldering processes create uneven surfaces on the outer circumference of the separating element and / or surfaces that protrude beyond the outer circumference geometry of the core tube, which can impair the functionality / assembly capability of the core tube and therefore must be laboriously removed, smoothed and / or adapted to the outer circumference geometry of the core tube.

[0004] The object of the invention is, in particular, to provide a generic method with advantageous properties for the production of magnetically separated core tubes, especially while maintaining fine cone geometries and preferably also keeping production costs low. This object is achieved according to the invention by the features of claims 1, 11 and 16, while advantageous embodiments and further developments of the invention can be found in the dependent claims. Advantages of the invention

[0005] The invention relates to a method for manufacturing a core tube for a magnetic actuator, which has a magnetic separation, preferably pressure-tight, at least along a longitudinal direction of the core tube.

[0006] According to the invention, in at least one process step, a separating element, which generates the magnetic separation of the core tube and is made of a non-magnetic material, in particular a non-magnetic metal, is inserted into the core tube by means of laser powder deposition welding. This allows for a particularly advantageous production of the magnetically separated core tube. Advantageously, the temperature to which parts of the core tube are exposed during the insertion of the separating element can be kept low, preferably so low that melting of the core tube and thus, in particular, damage to the core tube and / or a magnetic field conducting contour of the core tube, especially in the connection area between the core tube and the separating element, can be prevented.At the same time, the temperature can be advantageously chosen to be high enough to ensure a good and pressure-tight bond between the separating element and the core tube. This allows for a particularly good and / or durable bond between the core tube and the separating element. Laser powder deposition welding also allows for precise control of the energy input generated by the laser, and thus precise temperature control of the process. In contrast to prior art methods, where generally too much material is melted into the magnetic separation to achieve a reliable bond across the entire area of ​​the core tube covered by the separating element, this method allows for precise adjustment of the amount of material melted to the specific core tube geometry.Advantageously, this eliminates the need for post-processing after inserting the separating element into the core tube, such as machining the outer circumference of the separating element. Laser powder deposition welding also advantageously achieves a smooth and / or flat surface on the outer circumference of the separating element, particularly without subsequent machining such as turning or machining. Furthermore, by controlling the energy input generated by the laser, the surface of the separating element on its outer circumference can be smoothed even during its insertion into the core tube. Finally, this process advantageously ensures a particularly high pressure tightness of the core tube containing the separating element, especially at the connection points between the core tube and the separating element.This advantageously results in a particularly good suitability of the core tube for magnetic actuators in hydraulic applications. It also advantageously ensures that the separating element is continuously and materially bonded to the core tube in contact areas.

[0007] A "core tube" is understood to be, in particular, a component of a magnetic actuator made of a magnetic flux-conducting (magnetic flux-bundling), especially (soft) magnetic, preferably ferromagnetic, material, which forms at least a large portion of the magnetic core of the magnetic actuator and / or which is arranged at least partially, preferably at least partially, within the interior of a magnetic coil of the magnetic actuator. In particular, the magnetic material is a magnetic material. In particular, the core tube is made at least partially of magnetic steel. In particular, the core tube, together with at least one magnetic coil of the magnetic actuator, forms an inductor. In particular, the core tube is at least partially and / or at least on one side tubular. In particular, the core tube is designed to at least partially accommodate a magnetic armature of the magnetic actuator.In particular, the core tube is designed to at least partially form a displacement space for the magnetic armature of the magnetic actuator. Specifically, the displacement space for the magnetic armature is formed by the tubular part of the core tube. In particular, the longitudinal direction of the core tube runs parallel to a tube axis, specifically a rotational symmetry axis, of the tubular part of the core tube. In particular, when mounted in a magnetic actuator, the longitudinal direction of the core tube runs parallel to a coil axis of the magnetic coil of the magnetic actuator. In this context, a "magnetic actuator" is understood to mean, in particular, a device designed to convert electrical power into mechanical power by means of a magnetic field.

[0008] The term "intended" is to be understood in particular as specifically programmed, designed, and / or equipped. The fact that an object is intended for a specific function is to be understood in particular as the object fulfilling and / or performing this specific function in at least one application and / or operating state. "A large proportion" is to be understood in particular as 51%, preferably 66%, preferably 75%, and particularly preferably 90%. "Materially bonded" is to be understood in particular as the mass components being held together by atomic or molecular forces. The term "pressure-tight" is to be understood in particular as pressure-tight at typical hydraulic pressures, preferably pressure-tight at least at pressures above 100 bar, advantageously pressure-tight at pressures above 200 bar, preferably pressure-tight at pressures above 300 bar, and particularly preferably pressure-tight at pressures above 500 bar.Preferably, the connection between the separating element and the main body of the core tube is designed in such a way that even at high pressures inside the core tube (for example, at pressures as listed above) no liquid and / or gas can escape from the core tube at the connection.

[0009] The term "magnetic separation" of the core tube is understood to mean, in particular, that two sections of the core tube (made of a magnetic material) are separated from each other in such a way that at least a large proportion of all magnetic field lines running through a first section of the core tube are prevented from passing directly into the second section of the core tube. "Magnetic separation" of the core tube is understood to mean, in particular, an interruption of the magnetic flux conductivity of the core tube. Specifically, the separating element is designed to create the magnetic separation of the core tube, especially in the longitudinal direction of the core tube. Specifically, the separating element is designed to interrupt the magnetic flux through the core tube along its longitudinal direction.In particular, the separating element is designed to redirect the magnetic field lines of the magnetic coil such that the magnetic field lines are guided out of the core tube in the area of ​​the transition from the core tube to the separating element. Specifically, the separating element is arranged in a region of the core tube which, in the assembled state of the magnetic actuator, is located inside the coil of the magnetic coil. Specifically, the separating element is arranged in a region of the core tube which, in the assembled state of the magnetic actuator, forms the displacement space for the magnetic armature. In laser powder deposition welding, a powdered filler material, which preferably forms the separating element in the finished state, is melted with laser energy and thereby welded onto an existing component, for example, the core tube.Advantageously, this process creates a pore- and crack-free layer and / or element, such as the separating element, particularly with low dilution and a small heat-affected zone. Specifically, the separating element is seamlessly integrated between the two longitudinally separated magnetic sections of the core tube during laser powder deposition welding. The resulting magnetic actuator component, formed from the two core tube sections and the separating element, is designed as an integral and / or one-piece component. The separating element also serves to stabilize and / or seal the core tube.

[0010] Furthermore, according to the invention, in at least one preparatory step, preferably carried out before the process step, a core tube blank, which in particular will form the core tube in its finished state, is provided on its outer circumference with a circumferential groove into which the separating element is inserted in the process step. This enables an advantageous manufacturing process. Advantageously, this allows for the simple insertion of the separating element into the core tube. Advantageously, it allows for simple and / or precise positioning and / or shaping of the separating element. In particular, the circumferential groove is turned into the core tube blank in the preparatory step. Alternatively, however, it is also conceivable that a core tube blank already containing the groove is cast in the process step.The core tube blank is designed, in particular, as a solid, and especially at least substantially cylindrical, part, preferably made of steel. Alternatively, the core tube blank is designed as an at least partially hollowed-out and / or at least partially tubular part, preferably made of steel. In this case, the core tube blank can, in particular, be a drawn steel tube. The outer circumference of the core tube blank is, in particular, formed by a cylindrical surface, especially a cylindrical surface.

[0011] Furthermore, it is proposed that in the preparatory step, at least one lateral boundary of the groove be provided with a magnetic field guide contour, which, in particular, will form a conical geometry of the finished core tube to influence and / or design a force-displacement characteristic of the magnetic actuator containing the core tube. This enables an advantageous manufacturing process. Advantageously, the force-displacement characteristic of the magnetic actuator containing the finished core tube can be determined by selecting the shape of the magnetic field guide contour. In particular, the lateral boundary limits the groove at least substantially in a direction parallel to the longitudinal direction. Specifically, at least the lateral boundary of the groove, which limits the groove in the direction of the magnetic core and / or in a direction pointing away from the magnetic armature, is provided with the magnetic field guide contour.In particular, the magnetic field guide contour is arranged on a side of the groove facing the magnetic core. In particular, the magnetic field guide contour is designed as a sequence of edges, angles, and / or radii. In particular, the magnetic field guide contour comprises at least two different radii. In particular, the magnetic field guide contour comprises at least two edges. However, it is also conceivable that the magnetic field guide contour has only one edge and two surfaces, or only one radius and two surfaces, or the like. In particular, the magnetic field guide contour is designed such that a particularly good and / or particularly lossless transition of the magnetic field from the magnetic core to the magnetic armature can occur. In particular, the shape of the magnetic field guide contour is determined in a calculation and / or simulation step. In particular, the magnetic field guide contour can have different shapes depending on the desired force-displacement characteristic of the magnetic actuator.In particular, the magnetic field guide contour, especially its conical geometry, remains at least substantially unchanged in its shape during laser powder deposition welding. "Substantially unchanged" means, in particular, that deviations of the magnetic field guide contours before and after laser powder deposition welding at any point on the magnetic field guide contour are less than 0.2 mm, preferably less than 0.1 mm, and more preferably less than 0.05 mm. In particular, the magnetic field guide contour is rotationally symmetrical. In particular, the magnetic field guide contour is screwed into the core tube. In particular, one of the lateral boundaries, opposite the lateral boundary of the groove, is free of a magnetic field guide contour.

[0012] In a method known from documents US 2010 / 024200 A1, DE 100 38 139 A1, JP H09 312208 A and DE 100 31 686 A1, the non-magnetic material in powder form is blown into the groove and then melted by a laser beam, in particular to form the separating element.

[0013] According to the invention, however, in the process step, the non-magnetic material in powder form is blown into a laser beam, melted within the laser beam, and then introduced into the groove in its already molten state. This advantageously allows for a particularly high production speed, especially by enabling higher melting rates and / or shorter process times. The non-magnetic material in powder form is thus melted "in flight" and impacts the surface of the core tube blank in the groove area in liquid form. Advantageously, this allows significantly more material to be melted and introduced into the groove compared to the prior art, thereby significantly reducing the process time.

[0014] Furthermore, it is proposed that the powdered non-magnetic material blown into the laser beam and melted within it during the process step be a non-magnetic metal powder. This allows for advantageous properties regarding pressure tightness and / or stability, particularly since the separating element is then also metallic. The non-magnetic material of the metal powder must be sufficiently non-magnetic to function as a magnetic separator for the core tube. The non-magnetic material of the metal powder must, in particular, exhibit sufficient strength in the molten and re-solidified state to ensure stable core tube formation.For example, the powdered, non-magnetic material blown into the laser beam and melted in the laser beam during the process step is configured as a metal powder made of non-magnetic stainless steel, aluminum bronze, an aluminum alloy, bronze, and / or a CuSi alloy. In this context, "stainless steel" is understood to mean an alloyed or unalloyed steel with a high degree of purity, in particular with a purity level where the iron impurity mass fraction is less than 0.025%. Preferably, the stainless steel meets the requirements of a stainless steel and / or is configured as a stainless steel. Preferably, the stainless steel is configured as a stainless steel with an at least predominantly austenitic microstructure, and more preferably with an almost exclusively austenitic microstructure.

[0015] It is further proposed that, in at least one additional process step, after the separating element has been inserted into the groove, an armature receiving recess is introduced into the core tube blank, in particular by drilling or turning, which preferably extends beyond the groove in the longitudinal direction, especially of the core tube. This enables an advantageous manufacturing process for the magnetically separated core tube. Advantageously, this allows for the simple insertion of the separating element between two completely or almost completely separated sections of the core tube, in particular the main body of the core tube. The armature receiving recess is designed, at least in the assembled state of the magnetic actuator, to receive the magnetic armature. The armature receiving recess forms, in particular, the stroke volume for the magnetic armature.In particular, the armature mounting recess extends between the magnetic core and an armature stop element of the magnetic actuator.

[0016] If, in a subsequent process step, the core tube blank is hollowed out to the bottom of the groove during the creation of the armature recess, a simple and complete separation of the two longitudinally spaced sections of the core tube, particularly the main body of the core tube, can advantageously be achieved. Advantageously, a particularly good magnetic separation of the two longitudinally spaced sections of the core tube can be achieved. Advantageously, a particularly effective transfer of the magnetic field from the magnetic core to the magnetic armature can be achieved.

[0017] Alternatively, if in the subsequent process step the core tube blank is hollowed out to such an extent during the creation of the armature receiving recess that only a thin web made of the core tube blank material, particularly with a thickness of less than 0.5 mm and preferably less than 0.2 mm, remains between the groove base and an inner surface of the armature receiving recess, a particularly good pressure tightness can be advantageously achieved while simultaneously maintaining sufficient magnetic separation. In particular, magnetic field saturation is reached very quickly in the remaining thin web, so that the deterioration of the overall system's magnetic properties caused by the remaining thin web is negligible. It is conceivable that the hollowing of the core tube blank is carried out before the laser powder deposition welding process step.

[0018] Furthermore, in another alternative of the invention, it is proposed that the core tube blank, into which the groove is introduced in the preparatory step, is designed as a drawn tube which already has an armature receiving recess. This allows the armature receiving recess to be produced without machining. This advantageously eliminates the need for internal machining of the core tube, in particular the core tube blank. Moreover, a drawn tube has particularly advantageous internal surfaces with respect to friction with the magnetic armature, which are especially reduced compared to an internal surface produced by machining.

[0019] Furthermore, it is proposed that in this process step, the separating element is inserted so precisely into a groove of the core tube that a surface of the separating element and a surface of the core tube merge seamlessly. This advantageously eliminates the need for subsequent machining of the outer circumference. This, in turn, allows for increased process speed and reduced process costs. In particular, the transition between the surface of the separating element and the surface of the core tube is smooth or at least virtually smooth. Preferably, any step at the transition between the surface of the separating element and the surface of the core tube is less than 0.5 mm, more preferably less than 0.2 mm. It is also conceivable that the separating element is tapered in a central region.In this case, the surface of the core tube transitions smoothly and / or without steps, preferably at both axial end regions, into the surface of the separating element. Subsequently, the separating element tapers, at least in a central region. The external geometry of the separating element, tapered in the central region, fulfills the same function as a separating element with a completely flat surface, but is significantly easier and more cost-effective to manufacture.

[0020] Additionally, it is proposed that in at least one process step, after the insertion and at least partial curing of the separating element, particularly the non-magnetic material inserted into the groove, the laser beam or a further laser beam is passed again over a surface of the separating element, especially over a radially outward-facing surface of the non-magnetic material inserted into the groove, in order to smooth and / or equalize the surface of the separating element by remelting it, at least partially, particularly in a surface region of the separating element. This advantageously eliminates the need for subsequent machining of the outer circumference. This can also advantageously increase process speed and reduce process costs.Advantageously, a level and / or step-free transition from core tube to separating element can be easily created and / or ensured.

[0021] Furthermore, a magnetic actuator device is proposed, comprising a core tube that is at least substantially magnetically separated along its longitudinal direction by the separating element, and wherein the separating element is metallurgically bonded into the core tube by means of laser powder deposition welding. This advantageously allows a magnetic actuator device to be achieved with a magnetically separated and simultaneously pressure-tight core tube. In this context, "magnetic actuator device" is understood to mean at least one part, and in particular a subassembly, of the magnetic actuator. Advantageously, the magnetic actuator device is intended for use in a hydraulic system. In particular, the magnetic actuator device can also include an actuator housing, advantageously designed as an outer housing, and in particular at least for receiving the core tube, the magnetic armature, and / or the magnetic coil.

[0022] Furthermore, it is proposed that the core tube, at an interface with the separating element, has a magnetic field guiding contour, in particular a circumferential one, which forms a conical geometry to influence the force-displacement characteristic of a magnetic actuator containing the core tube. This allows, in particular, advantageous magnetic field shaping to achieve a desired shape for the force-displacement characteristic of the magnetic actuator.

[0023] Furthermore, it is proposed that the separating element be arranged in a region of the armature receiving recess of the core tube. This allows, in particular, advantageous magnetic field shaping to achieve a desired force-displacement characteristic curve of the magnetic actuator. If the separating element extends from the outer circumference of the core tube to an inner circumference of the armature receiving recess, a particularly effective magnetic separation of the core tube, especially of the two sub-regions of the core tube, can advantageously be achieved.

[0024] Alternatively, if the separating element extends from an outer circumference of the core tube towards the anchor receiving recess, wherein the separating element is separated from the anchor receiving recess by a thin web formed by the core tube, in particular with a thickness of less than 0.5 mm, preferably less than 0.2 mm, a particularly high pressure tightness can be advantageously achieved with simultaneously sufficiently good magnetic separation of the two sub-areas of the core tube.

[0025] Furthermore, the magnetic actuator, in particular a magnetic actuator for hydraulic applications, is proposed with the magnetic actuator device.

[0026] The inventive method, the inventive magnetic actuator device, and the inventive magnetic actuator are not intended to be limited to the application and embodiment described above. In particular, the inventive method, the inventive magnetic actuator device, and the inventive magnetic actuator may, to achieve a functionality described herein, comprise a different number of individual process steps, elements, components, and units than the number specified herein. Drawings

[0027] Further advantages will become apparent from the following description of the drawings. The drawings illustrate two exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0028] They show: Fig. 1 a schematic sectional view of a magnetic actuator with a magnetic actuator device, Fig. 2 a schematic detailed sectional view of the magnetic actuator device with a core tube and with a separating element, Fig. 3 a schematic sectional view of the core tube in a partially manufactured state, i.e. as a partially machined core tube blank, Fig. 4 a schematic flow diagram of a method for manufacturing the core tube magnetically separated by the separating element, Fig. 5 a schematic sectional view of a second variant of the core tube in a partially manufactured state, i.e. as a partially machined alternative core tube blank, Fig. 6 a schematic detailed sectional view of an alternative magnetic actuator device with an alternative core tube and with an alternative separating element, and Fig. 7 a detail of a schematic sectional view of the magnetic actuator device with the core tube and with an alternative separating element. Description of the exemplary implementations

[0029] Fig. 1Figure 1 shows a schematic sectional view of a magnetic actuator 12a. The magnetic actuator 12a is intended for hydraulic applications. The magnetic actuator 12a comprises a magnetic armature 54a. The magnetic armature 54a is surrounded by a fluid, in particular a hydraulic fluid (not shown). The magnetic armature 54a is made, at least in large part, of a magnetic, in particular ferromagnetic, material, for example, magnetic steel. The magnetic actuator 12a comprises a magnetic coil 56a. The magnetic coil 56a comprises a winding body 74a. The magnetic coil 56a comprises a plurality of coil windings (not shown). The coil windings are wound onto the winding body 74a. The coil windings of the magnetic coil 56a are wound around a coil shaft 62a of the magnetic coil 56a. The magnetic coil 56a is intended to generate a magnetic field, which in turn is intended to generate movement of the magnetic armature 54a.The magnetic armature 54a is designed to move in directions parallel to the coil axis 62a. The magnetic armature 54a is made of a material that conducts and focuses the magnetic field of the magnetic coil 56a. The magnetic coil 56a has an interior 58a. A large part of the movement of the magnetic armature 54a takes place within the interior 58a. The magnetic actuator 12a includes a plunger element 64a. The plunger element 64a is designed to transmit movement of the magnetic armature 54a outwards (out of the magnetic actuator 12a). The plunger element 64a is operatively connected to the magnetic armature 54a. The plunger element 64a follows the movement of the magnetic armature 54a. The plunger element 64a is movable parallel to the coil axis 62a. The magnetic actuator 12a comprises a magnetic yoke 66a. The magnetic yoke 66a surrounds the magnetic coil 56a at least partially on one outer surface of the magnetic coil 56a. The magnetic actuator 12a comprises an actuator housing 68a.The actuator housing 68a forms the outer boundary of the magnetic actuator 12a. The magnetic actuator 12a includes a connector element 72a. The connector element 72a is designed for a power connection to the magnetic actuator 12a, in particular to the magnetic coil 56a. The connector element 72a is shown only as an example and can have various different designs depending on the application or area of ​​use.

[0030] The magnetic actuator 12a comprises a magnetic actuator device 48a. The magnetic actuator device 48a comprises a core tube 10a. The core tube 10a is made, at least for a large portion, of a magnetic, in particular ferromagnetic, material, for example, magnetic steel. The core tube 10a is made of a material that conducts and focuses the magnetic field of the magnetic coil 56a. The core tube 10a can be made, at least for a large portion, of the same material as the magnetic armature 54a. Alternatively, the core tube 10a and the magnetic armature 54a can also be made of different materials. The core tube 10a extends along the coil axis 62a of the magnetic coil 56a. The core tube 10a is arranged, at least for a large portion, within the coil interior 58a of the magnetic coil 56a. The core tube 10a is fixed relative to the magnetic coil 56a. The core tube 10a has a longitudinal direction 14a.The longitudinal direction 14a of the core tube 10a runs at least substantially parallel to the coil axis 62a of the magnetic coil 56a. The core tube 10a is pressure-tight sealed to the outside. For pressure-tight sealing of the core tube 10a, the magnetic actuator device 48a comprises two O-rings 76a, 78a, which seal the core tube 10a pressure-tight at opposite ends. One of the O-rings 76a seals the magnetic actuator 12a on a connection side 86a of the magnetic actuator 12a, for example, against a hydraulic system to which the magnetic actuator 12a is connected.

[0031] The magnetic actuator device 48a comprises an armature stop element 60a. The armature stop element 60a is designed to limit the movement of the magnetic armature 54a in at least one direction parallel to the longitudinal direction 14a of the core tube 10a. The core tube 10a forms an armature receiving recess 34a. The magnetic armature 54a is received in the armature receiving recess 34a. The core tube 10a forms a stroke 80a. The stroke 80a defines a movement space for the magnetic armature 54a. The armature stop element 60a limits the stroke 80a on one side. The armature stop element 60a is preferably made of a metal. The armature stop element 60a is connected to an end region of the core tube 10a, preferably by press fit and / or positive locking. The connection between the interior of the core tube 10a and the anchor stop element 60a is sealed pressure-tight by means of the O-ring 78a.

[0032] The magnetic actuator device 48a has a magnetic core 70a. The core tube 10a transitions into the magnetic core 70a at one end. The core tube 10a transitions into the magnetic core 70a on the side opposite the armature stop element 60a.

[0033] The magnetic armature 54a is fully enclosed within the core tube 10a. The plunger element 64a is partially enclosed within the core tube 10a. The plunger element 64a is partially enclosed within the magnetic core 70a. The plunger element 64a protrudes from the magnetic core 70a at the connection end 86a. The core tube 10a is predominantly tubular. The magnetic core 70a has a plunger receiving recess 88a, which is designed to receive the plunger element 64a when the magnetic actuator 12 is assembled. The core tube 10a adjoining the magnetic armature 70a forms at least a large part of the stroke volume 80a for the magnetic armature 54a.

[0034] The Fig. 2schematically shows one in the Fig. 1The section of the magnetic actuator 12a is marked by a circle. The core tube 10a is completely magnetically separated along its longitudinal direction 14a. The magnetic actuator device 48a has a separating element 18a. The separating element 18a completely separates the core tube 10a into two parts that are not connected to each other, in particular not physically and not magnetically connected, and in particular into two sub-sections 82a and 84a of the core tube 10a. The separating element 18a is inserted between the two parts, in particular sub-sections 82a and 84a, of the core tube 10a. The separating element 18a is materially bonded to the two parts, in particular sub-sections 82a and 84a, of the core tube 10a. The separating element 18a is materially bonded to the two parts, in particular sections 82a and 84a, of the core tube 10a on opposite sides of the separating element 18a. The separating element 18a is pressure-tightly bonded to the two parts, in particular sections 82a and 84a, of the core tube 10a.The separating element 18a forms a pressure-tight magnetic separation of the core tube 10a into the two parts, in particular sub-areas 82a and 84a. The separating element 18a extends from an outer circumference 22a of the core tube 10a to an inner circumference 52a of the armature receiving recess 34a.

[0035] The separating element 18a is tubular, specifically designed as a pipe section. The separating element 18a is metallurgically bonded into the core tube 10a by means of laser powder deposition welding. The separating element 18a is made of a non-magnetic material 32a. The separating element 18a is made of a non-ferromagnetic material. The separating element 18a conducts the magnetic field of the magnetic coil 56a poorly or not at all.

[0036] The core tube 10a has an interface 50a with the separating element 18a. The separating element 18a is materially bonded to the interface 50a of the core tube 10a. The core tube 10a has a magnetic field guiding contour 28a at the interface 50a. The magnetic field guiding contour 28a surrounds the core tube 10a. The magnetic field guiding contour 28a forms a conical geometry that influences the force-displacement characteristic of the magnetic actuator 12a located within the core tube 10a. The magnetic field guiding contour 28a forms a conical geometry that influences the force-displacement characteristic of the magnetic armature 54a. The first subsection 82a of the core tube 10a, in particular the subsection 82a of the core tube 10a that transitions into the magnetic core 70a, forms the magnetic field guiding contour 28a. The magnetic field guiding contour 28a is arranged on a side of a part of the core tube 10a, in particular the first subsection 82a of the core tube 10a, preferably the magnetic core 70a, that faces away from the connection side 86a.The second section 84a of the core tube 10a, in particular the part of the core tube 10a forming the armature receiving recess 34a, is free of a magnetic field guide contour in the example shown in the figures. The separating element 18a is arranged in a region of the armature receiving recess 34a of the core tube 10a. The separating element 18a is arranged in a region of the magnetic actuator 12a in which the core tube 10a surrounds the armature receiving recess 34a.

[0037] The core tube 10a can be designed as a drilled or turned tube, i.e., in particular as a tube whose anchor receiving recess 34a and / or whose plunger receiving recess 88a are produced by machining a (solid body) core tube blank 92a, or as a drawn tube, i.e., in particular as a tube whose anchor receiving recess 34a and / or whose plunger receiving recess 88a are produced without machining a (solid body) core tube blank 92a.

[0038] The core tube 10a has a surface 46a on its outer circumference 22a. The separating element 18a has a surface 44a on its outer circumference 90a. The separating element 18a is inserted into the core tube 10a so precisely that the surface 44a of the separating element 18a and the surface 46a of the core tube 10a merge seamlessly. The transition between the surfaces 44a and 46a of the core tube 10a and the separating element 18a is essentially step-free.

[0039] The Fig. 3 shows a schematic sectional view of a section from the Fig. 2The corresponding section of a first variant of a core tube blank 92a, which has already been partially machined (by introducing a groove 24a), is shown. The core tube blank 92a is made of a cylindrical solid material. The core tube blank 92a has the groove 24a. The groove 24a runs around the core tube blank 92a. The groove 24a is machined into the core tube blank 92a. The groove 24a has lateral boundaries 26a, 94a. One of the lateral boundaries 26a forms the magnetic field guide contour 28a. The magnetic field guide contour 28a includes, by way of example, two (different) steps 96a, 98a. The magnetic field guide contour 28a includes, by way of example, two (different) radii 100a, 102a. Other magnetic field guide contours with significantly different designs than the magnetic field guide contour 28a shown are, of course, conceivable. The groove 24a has a groove base 36a.

[0040] The Fig. 4Figure 1 shows a schematic flowchart of a process for manufacturing the core tube 10a for the magnetic actuator 12a, which is magnetically separated by the separating element 18a. In at least one process step 106a, the core tube blank 92a is prepared. In a preparatory step 20a, the core tube blank 92a is provided with the circumferential groove 24a on its outer circumference 22a. In the preparatory step 20a, the lateral boundary 26a of the groove 24a is provided with the magnetic field guide contour 28a. The magnetic field guide contour 28a forms the conical geometry of the finished core tube 10a, which is intended for the targeted influencing of the force-displacement characteristic of the magnetic actuator 12a comprising the core tube 10a. The magnetic field guide contour 28a is screwed into the core tube blank 92a in the preparatory step 20a.

[0041] In process step 16'a, the separating element 18a, which creates the magnetic separation of the core tube 10a and is made of the non-magnetic material 32a, is inserted into the core tube 10a by means of laser powder deposition welding. In process step 16'a, the separating element 18a is inserted into the circumferential groove 24a created in preparation step 20a by means of the laser powder deposition welding process.

[0042] In process step 16'a, the non-magnetic material 32a in powder form is blown into the laser beam, whereupon the non-magnetic material 32a blown into the laser beam is melted by the laser beam. Subsequently, in process step 16'a, the non-magnetic material 32a, already molten, is introduced into the groove 24a of the core tube blank 92a.

[0043] The powdered, non-magnetic material 32a, which is blown into the laser beam and melted in the laser beam in process step 16'a, is in the form of a non-magnetic metal powder. The separating element 18a, inserted in process step 16'a, is inserted so precisely into the groove 24a of the core tube 10a by the laser powder deposition process that the surface 44a of the separating element 18a and the surface 46a of the core tube 10a merge seamlessly. In at least one process step 112a, after the separating element 18a has been fully inserted and at least partially hardened, the laser beam or another laser beam is passed over the surface 44a of the separating element 18a again. This smooths and / or equalizes the surface 44a of the separating element 18a by remelting the separating element 18a, at least partially.The entire manufacturing process can thus be advantageously free of any machining steps on the outer circumference 22a of the core tube 10a and on the outer circumference 90a of the separating element 18a.

[0044] In at least one further process step 30a, after the separating element 18a has been inserted into the groove 24a of the core tube blank 92a, the anchor receiving recess 34a, extending in the longitudinal direction 14a beyond the groove 24a, is introduced into the core tube blank 92a. In the further process step 30a, the anchor receiving recess 34a is drilled or screwed into the core tube blank 92a. In the further process step 30a, the core tube blank 92a is hollowed out up to the groove base 36a of the groove 24a during the introduction of the anchor receiving recess 34a, thereby completely separating the two sections 82a, 84a of the core tube 10a from each other (physically and magnetically). In this case, after carrying out the further process step 30a, no (magnetic) core tube material is present in the radial direction 108a of the core tube 10a above or below the separating element 18a.

[0045] In an alternative to the further process step 30a, a core tube blank 92b is hollowed out during the introduction of an anchor receiving recess 34b only to the extent that a thin web 40b consisting of the (magnetic) material of the core tube blank 92b remains between a groove base 36b of a groove 24b of the core tube blank 92b and an inner surface 38b of the introduced anchor receiving recess 34b. The remaining web 40b has a thickness 42b of less than 0.5 mm and preferably less than 0.2 mm. The alternative further process step 30b, in which the thin web 40b is retained, can be carried out before process step 16a, 16'a, in which the laser powder deposition welding of the separating element 18a takes place, or after process step 16a, 16'a, in which the laser powder deposition welding of the separating element 18a takes place.

[0046] Furthermore, if the thin web 40b below the separating element 18b is retained, the alternative further process step 30b, i.e., the hollowing out of the core tube blank 92b, can be completely omitted if an alternatively designed core tube blank 104b in the form of a drawn tube is used. In the preparatory step 20b, the groove 24b is introduced into the core tube blank 104b, which is already designed as a drawn tube and thus already has an anchor receiving recess 34b, in such a way that the thin web 40b remains after the preparatory step 20b has been carried out.

[0047] In at least one further process step 110a, the completed and magnetically at least substantially separated core tube 10a is mounted in a magnetic actuator 12a.

[0048] In the Figures 4(Partially), Figures 5 and 6 show a further embodiment of the invention. The following descriptions and drawings are essentially limited to the differences between the embodiments, whereby with regard to identically designated components, in particular components with the same reference numerals, reference is also generally made to the drawings and / or the description of the other embodiments, in particular the Figures 1 to 4 or 7 , can be referenced. To distinguish the embodiments, the letter a is the reference numeral of the embodiment in the Figure 1 , 2 , 3 , 4 (partially) and 7 appended. In the embodiment of the Figures 4 (partially), in 5 and 6 the letter a is replaced by the letter b.

[0049] The Fig. 5 shows a schematic sectional view of a section from the Fig. 2a corresponding section of a second variant of a core tube blank 104b that has already been partially machined (by introducing a groove 24b). The core tube blank 104b is formed from a cylindrical tube. The core tube blank 104b is formed from a drawn cylindrical tube. The core tube blank 104b is formed from a seamless drawn cylindrical tube. The core tube blank 104b comprises an inner circumference 52b and an outer circumference 22b. The core tube blank 104b has the groove 24b. The groove 24b extends from the outer circumference 22b towards the inner circumference 52b. However, the groove 24b does not penetrate the tube wall of the core tube blank 104b. The groove 24b runs around the core tube blank 104b. The groove 24b is machined into the core tube blank 104b. The groove 24b has lateral boundaries 26b, 94b. One of the lateral boundaries 26b forms a magnetic field guide contour 28b. The groove 24b has a groove base 36b.Between the groove base 36b and the inner circumference 52b of the core tube blank 104b is a thin web 40b made of the same material as the core tube blank 104b. The web 40b has a thickness 42b of less than 0.5 mm.

[0050] The Fig. 6 shows one with the excerpt from the Fig. 2A corresponding section of an alternative magnetic actuator 12b with an alternative magnetic actuator device 48b. The alternative magnetic actuator device 48b has an alternative separating element 18b and an alternative core tube 10b. The separating element 18b extends from an outer circumference 22b of the core tube 10b towards an armature receiving recess 34b formed by the core tube 10b. The separating element 18b is separated from the armature receiving recess 34b by the thin web 40b formed by the core tube 10b, which has a thickness 42b of less than 0.5 mm. When the magnetic actuator 12b is energized, the thin web 40b very quickly reaches complete magnetic field saturation, so that the force-displacement characteristic of the magnetic actuator 12b is not, or only insignificantly, influenced or impaired by the thin web 40b.

[0051] The Fig. 7Figure 1 schematically shows a section of the magnetic actuator device 48a with the core tube 10a and the separating element 18a. The separating element 18a transitions into the core tube 10a in edge regions 116a and 120a. The separating element 18a has a taper 114a in a central region 118a. Reference sign

[0052] 10 Core tube 12 Magnetic actuator 14 Longitudinal direction 16 Process step 18 Separating element 20 Preparation step 22 Outer circumference 24 Groove 26 Lateral boundary 28 Magnetic field guide contour 30 Further process step 32 Non-magnetic material 34 Armature recess 36 Groove base 38 Inner surface 40 Web 42 Thickness 44 Surface 46 Surface 48 Magnetic actuator device 50 Interface 52 Inner circumference 54 Magnetic armature 56 Magnetic coil 58 Coil interior 60 Armature stop element 62 Coil shaft 64 Plunger element 66 Magnetic yoke 68 Actuator housing 70 Magnetic core 72 Connector element 74 Winding body 76 O-ring 78 O-ring 80 Displacement 82 Partial area 84 Partial area 86 Connection side 88 Piston receiving recess 90 Outer circumference 92 Core tube blank 94 Lateral boundary 96 Step 98 Step 100 Radius 102 Radius 104 Core tube blank 106 Process step 108 Radial direction 110 Process step 112 Process step 114 Tapering 116 Edge area 118 Middle area 120 Edge area

Claims

1. Method for producing a core tube (10a; 10b) for a magnetic actuator (12a; 12b) which has, at least along a longitudinal direction (14a; 14b) of the core tube (10a; 10b), a - preferably pressure-tight - magnetic separation, wherein in at least one method step (16'a; 16'b), a separating element (18a; 18b), which produces the magnetic separation of the core tube (10a; 10b) and is made of a non-magnetic material (32a; 32b), is inserted into the core tube (10a; 10b) by material bonding by means of laser-powder deposition welding, and wherein, in at least one preparatory step (20a; 20b), a core tube blank (92a; 92b, 104b) is on its outer circumference (22a; 22b) provided with a circumferential groove (24a; 24b) into which the separating element (18a; 18b) is inserted in the method step (16'a; 16'b), characterized in that in the method step (16'a; 16'b), the non-magnetic material (32a; 32b) is blown in powder form into a laser beam, is melted in the laser beam and then in already melted form is introduced into the groove (24a; 24b).

2. Method as claimed in claim 1, characterized in that in the preparatory step (20a; 20b), at least one side boundary (26a; 26b) of the groove (24a; 24b) is provided with a magnetic field conduction contour (28a; 28b), which will in particular form a cone geometry of the completed core tube (10a; 10b) for influencing a force-travel curve of the magnetic actuator (12a; 12b) having the core tube (10a; 10b).

3. Method as claimed in claim 1 or 2, characterized in that in the method step (16'a; 16'b), the powdery non-magnetic material (32a; 32b) blown into the laser beam and melted in the laser beam is realized as a non-magnetic metal powder.

4. Method as claimed in one of the preceding claims, characterized in that in at least one further method step (30a; 30b), after insertion of the separating element (18a; 18b) into the groove (24a; 24b), an armature receiving recess (34a; 34b) is produced in the core tube blank (92a; 92b) and preferably extends beyond the groove (24a; 24b) in the longitudinal direction (14a; 14b).

5. Method as claimed in claim 4, characterized in that in the further method step (30a), during the production of the armature receiving recess (34a), the core tube blank (92a) is hollowed out down to a groove bottom (36a) of the groove (24a).

6. Method as claimed in claim 4, characterized in that in the further method step (30b), during the production of the armature receiving recess (34b), the core tube blank (92b) is hollowed out until only a thin web (40b) consisting of the material of the core tube blank (92b) remains between a groove bottom (36b) of the groove (24b) and an inner surface (38b) of the armature receiving recess (34b), in particular a web (40b) with a thickness (42b) of less than 0.5 mm and preferably less than 0.2 mm.

7. Method as claimed in claim 6, characterized in that the hollowing-out of the core tube blank (92b) is executed already before performance of the method step (16'b) with the laser powder deposition welding.

8. Method as claimed in one of claims 1 to 3, characterized in that the core tube blank (104b), in which the groove (24b) is produced during the preparatory step (20b), is embodied as a drawn tube which already has an armature receiving recess (34b).

9. Method as claimed in one of the preceding claims, characterized in that in the method step (16'a; 16'b), the separating element (18a; 18b) is inserted into a groove (24a; 24b) of the core tube (10a; 10b) so precisely that a surface (44a; 44b) of the separating element (18a; 18b) and a surface (46a; 46b) of the core tube (10a; 10b) merge evenly into one another.

10. Method as claimed in one of the preceding claims, characterized in that in at least one method step (112a; 112b), after completion of the insertion and at least partial hardening of the separating element (18a; 18b), the laser beam or a further laser beam is again passed over a surface (44a; 44b) of the separating element (18a; 18b) in order to thus smooth and / or equalize the surface (44a; 44b) of the separating element (18a; 18b) by further, at least partial melting of the separating element (18a; 18b).

11. Magnetic actuator device (48a; 48b), with at least one core tube (10a; 10b), which is at least substantially magnetically separated along its longitudinal direction (14a; 14b) by an, in particular pressure-tight, separating element (18a; 18b), characterized in that by means of laser powder deposition welding, in which a non-magnetic material (32a; 32b) is blown in powder form into a laser beam, is melted in the laser beam and then in already melted form is introduced into a circumferential groove (24a; 24b) situated on an outer circumference (22a; 22b) of a core tube blank (92a; 92b, 104b), the separating element (18a; 18b) is inserted into the core tube (10a; 10b) by material bonding.

12. Magnetic actuator device (48a; 48b) as claimed in claim 11, characterized in that the core tube (10a; 10b), at an interface (50a; 50b) to the separating element (18a; 18b), has an, in particular circumferential, magnetic field conduction contour (28a; 28b), which in particular forms a cone geometry for influencing a force-travel curve of a magnetic actuator (12a; 12b) having the core tube (10a; 10b).

13. Magnetic actuator device (48a; 48b) as claimed in claim 11 or 12, characterized in that the separating element (18a; 18b) is arranged in a region of an armature receiving recess (34a; 34b) of the core tube (10a; 10b).

14. Magnetic actuator device (48a; 48b) as claimed in claim 13, characterized in that the separating element (18a) extends from an outer circumference (22a) of the core tube (10a) to an inner circumference (52a) of the armature receiving recess (34a).

15. Magnetic actuator device (48a; 48b) as claimed in claim 13, characterized in that the separating element (18b extends from an outer circumference (22b) of the core tube (10a) towards the armature receiving recess (34b), wherein the separating element (18b) is separated from the armature receiving recess (34b) by a thin web (40b) formed by the core tube (10b), in particular with a thickness (42b) of less than 0.5 mm, preferably less than 0.2 mm.

16. Magnetic actuator (12a; 12b), in particular a magnetic actuator (12a; 12b) for hydraulic applications, having a magnetic actuator device (48a; 48b) as claimed in one of claims 11 to 15.