Subframe for a vehicle and assembly comprising such a subframe and a separately manufactured vehicle part

Abstract

The invention relates to a subframe (1) for a vehicle, having a metal component (1.2) which has a connection area (1.3) with an opening, the opening (1.9) being provided for attaching a screw (30) for producing a screw connection to a separately manufactured vehicle part (20). In order for such a subframe to provide a high or increased strength of the non-positive connection of the vehicle part at low cost and to provide low-cost corrosion protection, the invention provides that the connection area (1.3) has a surface structure (16) with metallic elevations (16.1) and recesses (16.2) which is arranged at the opening (1.9) and produced by laser irradiation, the metallic elevations (16.1) being in particular elevations which, relative to a reference surface ( R) of the connection area (1.3), have heights of at least 10 µm, preferably of at least 50 µm, particularly preferably of at least 200 µm or of greater than 250 µm. At least the connection area of the metal component of the subframe (1) including the surface structure (16) is coated with anti- corrosion lacquer, wherein the layer (18) of anti-corrosion lacquer has an average layer thickness which is less than the heights of at least a plurality of the metallic elevations (16.1) of the surface structure (16). In addition, an assembly is described and claimed which has a subframe (1) according to the invention and a separately manufactured vehicle part (20) which has a connection area made essentially of metal, preferably steel, and is connected to the metal component (1.2) of the subframe (1) at its connection area by means of a screw (30).

Description

[0001] Subframe for a vehicle and assembly comprising such a subframe and a separately manufactured vehicle part

[0002] The invention relates to a subframe for a vehicle, in particular a motor vehicle, having a metal component which has a connection area with an opening, the opening being provided for attaching a screw for producing a screw connection with a separately manufactured vehicle part.

[0003] Furthermore, the invention relates to an assembly (component assembly) with a subframe of the aforementioned type and a separately manufactured vehicle part which has a connection area essentially made of metal, preferably steel, and is connected to the metal component of the subframe at its connection area by means of a screw.

[0004] Subframes for motor vehicles, also known as axle carriers, are known in a variety of designs. They are to be as light as possible, with high strength and rigidity and usually have control arm connections (bearing mounts) for chassis elements, in particular wheel guide elements and other units, in order to enable the installation of complete front or rear axle modules, in particular those with drive units, as a pre-assembly unit.

[0005] Various methods are known for increasing the strength of friction-locked component connections, in particular screw connections, during the assembly of chassis and / or body components.

[0006] A simple measure is to use a screw with a higher load-bearing capacity, i.e. the dimension of the screw used is increased from M12 to M14 or M16, for example.

[0007] However, the use of larger screws or a higher number of screw connections leads to higher costs and a higher weight of the component assembly. When using larger screws, the increase in strength is based on an increase in screw preload. However, this cannot be increased at will, particularly in the case of lightweight components made of aluminium or thin steel sheets.

[0008] It is also known to increase the strength of the connection of components to be joined by means of an additionally implemented friction coefficient increase. For this purpose, surfaces in the connection area of the components to be joined are usually coated with friction-enhancing material or mechanically roughened by removing material (see e.g. DE 102007016643 Al). However, the additional coating with friction-enhancing material is time-consuming and costly. Intensive removal of surface material to roughen the connection area can lead to considerable weakening of the relevant component at the screw connection due to the hardness and relatively low thickness of the steel sheets used in body construction in particular.

[0009] Furthermore, chassis and / or body components are coated with lacquer by cathodic dip coating or with a metallic coating (e.g. zinc or nickel) by electroplating before assembly for reasons of corrosion protection. However, a lacquer coating in particular leads to a considerable reduction in the previously applied mechanical roughening or even cancels it out completely. The friction coefficient is therefore usually increased by means of additionally applied auxiliary means such as toothed discs (see e.g.

[0010] EP 2902303 Al). However, the application of these auxiliary means causes additional material costs; moreover, the assembly process is more complex.

[0011] DE 102020105883 Al discloses a component arrangement with a first metal component, a second metal component and at least one screw connection which generates a contact pressure by means of which the first component and the second component are pressed together in a clamping manner. In a contact pressure area in which a contact surface of the first component and a contact surface of the second component are pressed together by the contact pressure, the contact surface of the first component has a coating in the form of a coat of lacquer, while the contact surface of the second component has a roughened surface. The surface roughening in the area of the contact surface is produced by blasting the surface of the second component, e.g. by sand or steel shot blasting. When the components are pressed together by the screw connection, the roughened surface of the second component digs into the coating of the first component without completely penetrating it.

[0012] The present invention is based on the object of creating a subframe of the type mentioned at the beginning, which provides a high or increased strength of the forcelocking connection of the vehicle part for the force-locking connection of a separately manufactured vehicle part, for example a chassis and / or body component, at low cost and has low-cost corrosion protection.

[0013] This object is solved by a subframe with the features specified in claim 1.

[0014] Advantageous embodiments of the invention are given in the subclaims dependent on claim 1.

[0015] The invention thus relates to a subframe for a vehicle, in particular a motor vehicle, having a metal component which has a connection area with an opening, the opening being provided for attaching a screw for producing a screw connection to a separately produced vehicle part. According to the invention, the connection area has a surface structure with metallic elevations and recesses which is arranged at the opening and produced by laser irradiation, wherein the metallic elevations are in particular elevations which, relative to a reference surface of the connection area, have heights of at least 10 pm, preferably of at least 50 pm, particularly preferably of at least 200 pm or greater than 250 pm, wherein at least the connection area of the metal component of the subframe, including the surface structure, is coated with anticorrosion lacquer, and wherein the layer of anti-corrosion lacquer has an average layer thickness which is less than the heights of at least a plurality of the metallic elevations of the surface structure.

[0016] The reference surface can be a reference surface or a reference interface. A reference interface is understood to be a surface covered by a layer of anti-corrosion lacquer. The invention represents a cost-effective solution for increasing the force transmission of mechanical connections on a subframe of the type mentioned at the beginning, with which a cost-effective corrosion protection of the subframe can also be achieved.

[0017] The invention is based on the idea that the hard metallic elevations of the surface structure of the metal component of the subframe are produced by laser irradiation with a height that is sufficient with respect to the layer thickness of the anti-corrosion lacquer applied to the surface structure to ensure that these elevations penetrate the surface of the vehicle part when the screw connection is made, i.e. when the metal component is pressed together with the separately manufactured vehicle part to be connected by the screw connection, these elevations penetrate the surface of the vehicle part to such an extent that a mechanical bond is created by means of a positive fit (e.g. micro-form fit).

[0018] To produce the surface structure of the metal component of the subframe, a reference surface of the metal component is melted and roughened in the specified connection area using a laser beam device. The power of the laser beam used for this can be in the range of 500 W to 1000 W, for example. The material of the elevations having peaks is raised from the surface material of the relevant metal component of the subframe, while at the same time recesses with sinks are created in the connection area processed by the laser beam device. The metallic elevations having peaks are clearly above the reference surface of the metal component; the recesses with sinks, on the other hand, are clearly below the reference surface or reference area of the metal component. The recesses can also be referred to as pores or depressions.

[0019] The metallic elevations of the surface structure of the metal component of the subframe produced by laser irradiation according to the invention enable a significant increase in force transmission in the connection area of the connected, separately manufactured vehicle part, e.g. chassis or body part. The metallic elevations of the surface structure of the metal component of the subframe according to the invention, in particular their peaks, can have heights relative to the reference surface or reference area of the metal component which are, for example, smaller than approx.900 pm, preferably smaller than approx. 700 pm, particularly preferably smaller than approx. 500 pm.

[0020] An advantageous embodiment of the invention provides that the average layer thickness of the layer of anti-corrosion lacquer, with which at least the connection area of the metal component of the subframe including the surface structure is coated, is in the range from 5 pm to 150 pm, preferably in the range from 10 pm to 100 pm, particularly preferably in the range from 15 pm to 80 pm. As a result, both long-lasting, robust corrosion protection and penetration by means of the metallic elevations of the surface structure and thus an effective form fit can be achieved in the connection area.

[0021] Preferably, the layer of anti-corrosion lacquer covers the entire surface of the metallic elevation of the surface structure.

[0022] According to a further advantageous embodiment of the invention, the layer of anticorrosion lacquer is applied to the subframe by cathodic dip coating (CDC). In the cathodic dip coating process, the workpiece to be coated is negatively charged electrically and immersed in an electrically conductive, aqueous lacquer bath with positively charged lacquer particles, which are attracted to the workpiece and deposited on it. The particles of the dipping lacquer can thus form an even layer of lacquer over the entire surface of the workpiece to be coated. The layer thickness with which the lacquer is deposited on the component depends on the part geometry and the level of voltage applied. After the lacquer layer has been applied, it is baked at approx. 180 to 220 °C in a baking oven. In this way, an anti-corrosion lacquer can be applied very efficiently and evenly. The layer thickness of the anti-corrosion lacquer applied by cathodic dip coating to the subframe according to the invention can, for example, be in the range from 5 pm to 50 pm, preferably in the range from 10 pm to 40 pm, particularly preferably in the range from 15 pm to 30 pm.

[0023] A further advantageous embodiment of the invention is characterised in that the metal component is formed from heat-hardenable steel, preferably heat-hardenable sheet steel, wherein the metallic elevations of the surface structure have a metal structure containing martensite. In this embodiment of the invention, the elevations of the surface structure, in particular their peaks, are characterised by a particularly high hardness. The high hardness of the elevations having peaks improves the penetration of the elevations into the vehicle part to be friction-locked to the subframe by a screw connection. This favours the formation of a micro-form-fit between the components to be friction-locked together by the screw connection.

[0024] A further advantageous embodiment of the invention provides that the surface structure of the metal component of the subframe has a hardness in the range from 350 to 550 HV0.1, preferably in the range from 400 to 500 HV0.1.

[0025] For a corresponding Vickers hardness test, a four-sided pyramid is pressed into the component or surface structure to be tested with a (relatively) small force and low penetration depth. The Vickers hardness test is regulated in the standard EN ISO 6507-1 to EN ISO 6507-4. The unit of the determined hardness is kp / mm2and is designated by the process name Vickers (HV = Vickers hardness). When specifying hardness, it is important to state the test force with which the hardness was determined, as there is a dependency between the hardness value and the test force (F). In the Vickers hardness test, a distinction is made between three test force ranges:

[0026] 1. Vickers hardness test: Test force F > 49.03 N,

[0027] 2. Vickers small force hardness test: 1.961 N < F < 49.03N, and

[0028] 3. Vickers microhardness test: 0.0098 N < F < 1.961 N.

[0029] For example, the hardness of a Vickers microhardness test with a test force of 0.981 N is specified as HV0.1, e.g.450HV0.1. Preferably, the invention comprises embodiments in which the metal component is formed from heat-hardenable steel, preferably heat-hardenable sheet steel, wherein the metal component has a metal structure containing ferrite / pearlite or bainite outside the surface structure. The metal component can thus have a lower hardness outside the surface structure, which can be advantageous, for example, with regard to further processing of the metal component, e.g. machining. This is because the machinability is in inverse proportion to the hardness of the material. Machining a very brittle material can result in the machining process, for example drilling or milling, no longer functioning satisfactorily due to excessive resistance to material removal by machining.

[0030] A further advantageous embodiment of the invention provides that the surface structure of the metal component surrounds the opening for the screw of the screw connection in the form of a ring, preferably an annular disc. This design contributes to a particularly effective increase in the friction coefficient in the relevant connection area of the subframe.

[0031] The invention can be advantageously realised in a subframe of the type mentioned at the beginning at various connection areas of the subframe. An advantageous embodiment of the invention exists in particular in the case of a connection of a subframe of the above-mentioned type to a car body. The subframe is preferably characterised in that the metal component is the upper shell of a subframe support composed of an upper shell and a lower shell, with the connection area being designed as a body connection area.

[0032] A further advantageous embodiment of the invention results in a connection of a steering gear housing or vehicle engine to a subframe of the above-mentioned type. Accordingly, an advantageous embodiment of the invention provides that the metal component of the subframe is a carrier or carrier part of the subframe, wherein the connection area is designed to connect a steering gear housing or vehicle engine. A further advantageous embodiment of the invention arises in the connection of a bearing, e.g. a bearing bush, of a tension strut or a bearing of a suspension control arm to a subframe of the above-mentioned type. In this case, the metal component can in turn be a carrier or carrier part of the subframe, whereby the connection area is designed to connect a bearing of a tension strut or a bearing of a suspension control arm.

[0033] The present invention relates in particular to an assembly (component assembly) comprising a subframe according to the invention, in particular according to one of the above-mentioned embodiments, and a separately manufactured vehicle part which has a connection area made essentially of metal, preferably steel, and is connected to the metal component of the subframe at its connection area by means of a screw, wherein elevations of the surface structure of the connection area of the metal component penetrate the connection area of the vehicle part, and wherein the vehicle part is made of steel or aluminium at the connection area.

[0034] The connection area of the separately manufactured vehicle part can also be coated with anti-corrosion lacquer.

[0035] A further advantageous embodiment of the assembly according to the invention is characterised in that elevations of the surface structure of the connection area of the metal component penetrate the connection area of the vehicle part without completely penetrating the layer or layers of anti-corrosion lacquer. This embodiment provides particularly effective corrosion protection, especially for the metal component of the subframe according to the invention and, if applicable, for the vehicle part connected to it in a friction-locked manner.

[0036] A further advantageous embodiment of the assembly according to the invention is characterised in that the penetration effects a mechanical bond of the connection areas by positive locking, whereby the elevations of the surface structure of the connection area of the metal component penetrate the connection area of the vehicle part in such a way that a plurality of the elevations completely penetrate the layer or layers of anti-corrosion lacquer. With this embodiment of the invention, sufficiently effective corrosion protection can also be achieved, in particular for the metal component of the subframe.

[0037] The invention is explained in more detail below with reference to a drawing illustrating several embodiments.

[0038] Fig. 1 shows a sectional view of two metal components that are to be joined together to form an assembly;

[0039] Fig. 2 shows a sectional view of the metal components from Fig. 1 in a force-fit connected state;

[0040] Fig. 3 shows a sectional view of two metal components that are also to be joined together to form an assembly;

[0041] Fig.4 shows a sectional view of the metal components from Fig. 3 in a force-fit connected state;

[0042] Fig. 5 shows a portion of a subframe for a vehicle, with a metal component having a connection area with an opening, wherein the opening is provided for attaching a screw for producing a screw connection with a separately manufactured vehicle part, in a sectional view;

[0043] Fig. 6 shows a portion of a (different) subframe for a vehicle, comprising a metal component having a connection area with an opening, wherein the opening is provided for attaching a screw for establishing a screw connection with a separately manufactured vehicle part, in a perspective view; Fig. 7a - 7c show an assembly of metal components connected to each other in a force-fit manner, in a side or top view, a sectional view and a perspective view;

[0044] Fig. 8a - 8c show a further example of an assembly of metal components connected to each other in a force-fit manner, in a side or top view, a sectional view and a perspective view;

[0045] Fig.9a -9f show a further example of an assembly of metal components connected to each other in a force-fit manner, in a top view, a side view, two sectional views and two perspective views;

[0046] Fig. 10 shows an enlarged perspective view of a section of a metal component with a through opening and a surface structure surrounding the through opening and produced by laser irradiation; and

[0047] Fig. 11 shows a perspective view of a section of a prior art subframe for a motor vehicle.

[0048] Fig. 11 shows a portion of a prior art subframe 1, namely a front axle subframe for a motor vehicle. The subframe 1 is assembled from longitudinal members and cross members. The term "longitudinal members" is understood here to mean supporting elements or portions of supporting elements of the subframe 1 which, when the subframe 1 is assembled, extend essentially along the longitudinal axis of the respective vehicle in question. The cross members, on the other hand, extend in the mounted state of the subframe 1 substantially horizontally and transversely to the longitudinal axis of the motor vehicle.

[0049] The longitudinal members and cross members are made of sheet metal shells. Fig. 11 shows the left-hand front longitudinal member 2, a front cross member 3 and an upper shell 4 serving as a cross member. Also shown are a plate 5 serving as steering protection, a crash absorber connecting plate 6 and so-called tower shells 7, 8, which serve to connect the subframe 1 to the vehicle body. The subframe 1 is designed for the connection of a so-called transverse bridge (not shown), which serves to mount a vehicle drive unit, for example an electric motor. The transverse bridge is connected to the longitudinal members 2 at mountings 9, which for example have through holes to accommodate screw bolts. The respective longitudinal member 2 of the subframe 1 has a first shell element 2.1 and a second shell element 2.2, which together define a cavity 10.

[0050] Adjacent to the through-holes 9 are (further) connecting elements 11 for connecting the subframe 1 to the vehicle body. The mounting of the transverse bridge and the connecting elements 11 for connecting the subframe to the vehicle body are realised by means of one or more spacer elements 12, 13. The spacer elements 12, 13 are designed, for example, in the form of cylindrical spacer sleeves 12 and / or in the form of a sleeve-like spacer element 13. The connecting elements 11 are provided with auxiliary means for increasing the friction coefficient for a screw connection, namely toothed washers 15. Attaching these auxiliary means (15) causes additional material costs and complicates the assembly process.

[0051] Figures 1 and 2 sketch a portion of an assembly which comprises a subframe 1 designed according to the invention and a separately manufactured vehicle part 20 which is connected to the subframe 1 in a friction-locked manner. The vehicle part 20 can, for example, be a metal component of a vehicle body, a metal component of a chassis component or a metal component of a steering component. The subframe 1 according to the invention has at least one metal component 1.2, which has a connection area 1.3 with an opening 1.9, wherein the opening 1.9 is provided for attaching a screw 30 for producing a screw connection with the separately manufactured vehicle part 20. A nut is designated by 40.

[0052] The subframe portion shown in Figures 1 and 2 is composed of an upper sheet metal shell 2.2 and a lower sheet metal shell 2.1, which together define a cavity 10. A spacer sleeve 12 is arranged in the cavity 20, which is connected, for example welded, to at least one of the sheet metal shells (2.1) by a material bond. The opening 1.9 for attaching the screw 30 is designed as a through opening. Each of the two sheet metal shells 2.1, 2.2 has such an opening 1.9, whereby the two openings (through openings) 1.9 are aligned with each other and are arranged in overlap with the longitudinal centre axis of the spacer sleeve 12.

[0053] The connection area 1.3 is provided with a surface structure 16, which is arranged at the opening 1.9 and produced by laser irradiation and which has metallic elevations 16.1 and recesses 16.2. The metallic elevations 16.1 are in particular elevations which have heights of at least 10 pm, for example of at least 50 pm, preferably of at least 200 pm, particularly preferably of greater than 250 pm, relative to a reference surface (i.e. a reference surface or reference interface) R of the connection area 1.3. This surface structure 16 produced by laser irradiation can also be referred to as roughening.

[0054] Fig. 10 shows an example of a corresponding surface structure 16 or roughening created by laser irradiation in an enlarged view. Fig. 10 shows a portion of a metal component 1.2 with a through opening 1.9. It can be seen that the surface structure 16 is formed in an annular shape around the opening 1.9 and thus surrounds the opening 1.9 in an annular shape.

[0055] Figures 1 and 2 show that at least the connection area 1.3 of the metal component 1.2 of the subframe, including the surface structure 16, is coated with anti-corrosion lacquer. The layer 18 of anti-corrosion lacquer has an average layer thickness that is less than the heights of at least a plurality of the metallic elevations 16.1 of the surface structure 16.

[0056] The average layer thickness of the layer 18 of anti-corrosion lacquer can be in the range from 5 pm to 150 pm, for example. Preferably, the average layer thickness of the anti-corrosion lacquer is in the range from 10 gm to 100 gm, particularly preferably in the range from 15 pm to 80 pm.

[0057] Furthermore, it is outlined in Fig. 1 that the layer 18 of anti-corrosion lacquer covers the entire surface of the metallic elevations 16.1 of the surface structure 16. The anticorrosion lacquer can be applied to the connection area of the metal component 1.2 of the subframe 1 in various ways. Preferably, the layer 18 of anti-corrosion lacquer is or will be applied to the subframe 1 by cathodic dip painting (CDP). It is understood that the entire subframe 1 can thus essentially be coated with anti-corrosion lacquer. Accordingly, all parts of the subframe 1 shown in the drawing, in particular the sheet metal shells 2.1, 2.2, the spacer sleeve(s) 12 and the walls of the openings 1.9 can also be coated on all sides with anti-corrosion lacquer.

[0058] The metal component 1.2 of the subframe, which has the connection area 1.3 with the opening 1.9 for attaching the screw 30, is preferably made of steel, particularly preferably of heat-hardenable sheet steel. In particular, the essential sheet metal parts of the subframe 1 according to the invention can be made of such steel. For example, the subframe 1 is made of micro-alloyed steel of the type S420 MC or a complex-phase steel of the type CP-W800. Sheet metal shells 2.1, 2.2 with very good mechanical properties for subframes of the type described here can be produced from sheet metal of these steel grades, in particular by cold forming. Type S420 MC steel has a ferritic / pearlitic metal structure, while type CP-W800 steel has a bainitic metal structure. Sheet steel of type S420 MC has a hardness in the range of approx. 185 to approx. 240 HV0.1 in the normal or formed state. The hardness of sheet steel of type CP-W800 is approx. 225 HV0.1 in the normal state.

[0059] Preferably, the surface structure 16 of the metal component 1.2 of the subframe 1 produced by laser irradiation is cooled so quickly after its production, for example quenched by forced cooling, that a metal structure containing martensite is produced at least in the metallic elevations 16.1 of the surface structure 16. This structural transformation simultaneously results in a considerable hardening of the surface structure (roughening) 16. The hardness of the surface structure 16 of the relevant metal component 1.2 of the subframe 1 according to the invention can, for example, be in the range of approximately 400 to 500 HV0.1.

[0060] The embodiment example sketched in Figures 3 and 4 differs from the example shown in Figures 1 and 2 in that the side / surface of the vehicle part 20 to be connected or connected facing the connection area, in particular the surface structure 16, of the metal component 1.2 of the subframe 1 is also coated with corrosion protection, preferably with corrosion protection lacquer. The layer thicknesses of the corrosion protection layers 18, 18' facing each other or lying against each other are dimensioned such that a plurality of the metallic elevations 16.1 of the surface structure 16 penetrate the corrosion protection layers 18, 18' and the metal component 20.2 or metal sheet of the vehicle part 20 without completely penetrating the corrosion protection layer 18 of the subframe 1 and / or the corrosion protection layer 18' of the vehicle part 20.

[0061] The embodiment example shown in Fig. 5 largely corresponds to the examples outlined in Figures 1 to 4. It is shown more clearly in Fig. 5 that a subframe 1 according to the invention can be composed in particular of sheet metal shells 2.1, 2.2 produced by forming sheet steel blanks. The same applies to a vehicle part 20 to be connected to the subframe 1 by a screw connection, for example a body part.

[0062] The embodiment example of a subframe 1 designed according to the invention shown in Fig. 6 differs from the portion of a prior art subframe shown in Fig. 11, in particular with regard to the omission of the toothed washers 15. Instead of such toothed washers 15, a subframe 1 designed according to the invention has surface structures 16 with metallic elevations 16.1 and recesses 16.2 arranged at the openings 1.9 of the connection area 1.3, wherein the metallic elevations 16.1 are in particular elevations which, relative to a reference surface R (i.e. a reference surface or reference interface) of the connection area 1.3, have heights of at least 10 pm, preferably of at least 50 pm, particularly preferably of at least 200 pm. The elevations 16.1 have peaks, while the recesses 16.2 define sinks. In addition, at least the connection area 1.3 of the relevant metal component 1.2 of the subframe 1 including the surface structure 16 is coated with anti-corrosion lacquer, wherein the layer 18 of anti-corrosion lacquer has an average layer thickness that is less than the heights of at least a plurality of the metallic elevations 16.1 of the surface structure 16. As is also shown in Fig. 6, the surface structure 16 surrounding a through opening 1.9 in the connection area 1.3 is, for example, annular in shape.

[0063] The embodiment example shown in Figures 7a to 7c largely corresponds to the examples outlined in Figures 1 to 4. Functionally corresponding components or parts are labelled with the same reference signs. The surface structure 16 produced by means of a laser beam, which is coated with a layer 18 of anti-corrosion lacquer, is located between the plate-shaped or carrier-shaped metal component 1.2 of the subframe 1 and the component (vehicle part 20) connected directly to it by a screw connection. To avoid repetition, reference is made to the preceding description, in particular to the description of the examples outlined in Figures 1 to 4.

[0064] The embodiment example shown in Figures 8a to 8c differs essentially from the example shown in Figures 7a to 7c in that a single plate-shaped or carrier-shaped metal component 1.2 of a subframe 1 according to the invention is used here for the direct connection of a separately manufactured vehicle part 20, the screw connection used for this purpose being designed in such a way that a comparatively short screw 30 is screwed into an internal thread 20.4 formed in the vehicle part 20. The surface structure 16 produced by means of a laser beam, which is coated with a layer of anticorrosion lacquer, is located between the plate-shaped or carrier-shaped metal component 1.2 and the vehicle part 20 connected to it by means of the screw connection. This schematically indicated vehicle part 20 can be, for example, the housing of a steering gear or an engine mount.

[0065] The embodiment shown in Figures 9a to 9f relates to the connection of a separately manufactured vehicle part 20 in the form of a bearing of a tension strut or a bearing of a chassis control arm to a subframe according to the invention. The bearing has, for example, a bush-shaped bearing body 25 which is made of metal, for example steel. The subframe 1 according to the invention has two plate-shaped or beam-shaped metal components 1.2 which are connected, for example screwed or welded, to a longitudinal member or cross member of the subframe at a distance from one another. The metal components 1.2 define a fork shaped mount (receptacle) for the bearing of the tension strut or the chassis control arm. In order to fix a certain rotational position of the bearing in the fork-shaped mount, the bearing body 25 made of metal is clamped between the metal components 1.2 by means of a screw connection. To increase the strength of the friction-locked component connection or to increase the friction coefficient, the two connection areas 1.3 of the metal components 1.2 facing the bearing body 25 are each provided with a surface structure 16 produced by laser irradiation, which has metallic elevations 16.1 and recesses. These surface structures 16 can be designed essentially like the surface structures described above with reference to Figures 1 to 6 and Fig. 10 or are designed in this way. In particular, at least the connection area 1.3 of the respective metal component 1.2 of the subframe including the associated surface structure 16 is coated with anti-corrosion lacquer, wherein the layer of anti-corrosion lacquer has an average layer thickness which is less than the heights of at least a plurality of the metallic elevations 16.1 of the surface structure 16.

[0066] The implementation of the invention is not limited to the embodiments shown in the drawing. Rather, numerous variants of the subframe according to the invention and of the described assembly comprising the subframe are conceivable, which also make use of the invention disclosed in the appended claims in a design deviating from the examples shown. In particular, it is within the scope of the invention to combine various of the features of the invention shown and / or described as well as of the embodiments with one another.

Claims

C l a i m s1. Subframe for a vehicle, in particular a motor vehicle, having a metal component (1.2) which has a connection area (1.3) with an opening (1.9), the opening being provided for attaching a screw (30) for producing a screw connection to a separately produced vehicle part (20), the connection area (1.3) having a surface structure (16) which is arranged at the opening (1.9), is produced by laser irradiation and has metallic elevations (16.1) and recesses (16.2), the metallic elevations (16.1) being in particular such elevations which, relative to a reference surface ( R) of the connection area (1.3), have heights of at least 10 pm, preferably of at least 50 pm, particularly preferably of at least 200 pm or of greater than 250 pm, wherein at least the connection area (1.3) of the metal component (1.2) of the subframe, including the surface structure (16), is coated with anti-corrosion lacquer, and wherein the layer (18) of anti-corrosion lacquer has an average layer thickness which is less than the heights of at least a plurality of the metallic elevations (16.1) of the surface structure (16).

2. Subframe according to claim 1, characterised in that the average layer thickness of the layer (18) of anti-corrosion lacquer is in the range from 5 pm to 150 pm, preferably in the range from 10 pm to 100 pm, particularly preferably in the range from 15 pm to 80 pm.

3. Subframe according to claim 1 or 2, characterised in that the layer (18) of anticorrosion lacquer covers the entire surface of the metallic elevations (16.1) of the surface structure (16).

4. Subframe according to one of claims 1 to 3, characterised in that the layer (18) of anti-corrosion lacquer is applied to the subframe (1) by cathodic dip coating.

5. Subframe according to one of claims 1 to 4, characterised in that the metal component (1.2) is formed from heat-hardenable steel, preferably heat- hardenable sheet steel, wherein the metallic elevations (16.1) of the surface structure (16) have a metal structure containing martensite.

6. Subframe according to one of claims 1 to 5, characterised in that the metal component (1.2) is formed from heat-hardenable steel, preferably heat- hardenable sheet steel, wherein the metal component (1.2) has a metal structure containing ferrite / pearlite or bainite outside the surface structure (16).

7. Subframe according to one of claims 1 to 6, characterised in that the surface structure (16) has a hardness in the range from 350 to 550 HV0.1, preferably in the range from 400 to 500 HV0.1.

8. Subframe according to one of claims 1 to 7, characterised in that the surface structure (16) surrounds the opening (1.9) in an annular shape.

9. Subframe according to one of claims 1 to 8, characterised in that the metal component (1.2) is the upper shell (2.2) of a subframe support composed of an upper shell (2.2) and a lower shell (2.1), the connection area (1.3) being designed as a body connection area.

10. Subframe according to one of claims 1 to 8, characterised in that the metal component (1.2) is a carrier or carrier part of the subframe (1), the connection area (1.3) being designed to connect a steering gear housing or vehicle engine.

11. Subframe according to one of claims 1 to 8, characterised in that the metal component (1.2) is a carrier or carrier part of the subframe (1), wherein the connection area (1.3) is designed to connect a bearing of a tension strut or a bearing of a suspension control arm.

12. Assembly with a subframe (1) according to one of claims 1 to 8 and a separately manufactured vehicle part (20), which has a connection area made essentially of metal, preferably steel, and is connected to the metal component (1.2) of the subframe (1) at its connection area by means of a screw (30), characterised in that elevations (16.1) of the surface structure (16) of the connection area (1.3) of the metal component (1.2) penetrate the connection area of the vehicle part (20), the vehicle part (20) being made of steel or aluminium at the connection area.

13. Assembly according to claim 12, characterised in that the connection area of the separately manufactured vehicle part (20) is also coated with anti-corrosion lacquer.

14. Assembly according to claim 12 or 13, characterised in that elevations (16.1) of the surface structure (16) of the connection area (1.3) of the metal component (1.2) penetrate the connection area of the vehicle part (20) without completely penetrating the layer (18) or layers (18, 18') of anti-corrosion lacquer.

15. Assembly according to claim 12 or 13, characterised in that the penetration effects a mechanical bond of the connection areas (1.3) by positive locking, the elevations (16.1) of the surface structure (16) of the connection area (1.3) of the metal component (1.2) penetrating the connection area of the vehicle part (20) in such a way that a plurality of the elevations (16.1) completely penetrate the layer (18) or layers (18, 18') of corrosion protection lacquer.

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