Method for assembling a tubular component of a motor vehicle to another component and component connection between a tubular component and another component and vehicle seat with such a component connection

Abstract

To form a component connection (2) between a tubular component (4) extending in a longitudinal direction (L) and another component (6), in particular a vehicle seat, an end region (12) of the component (4) is radially expanded with the aid of a forming mandrel (14) for axially positive fastening to the other component (6) by screwing the mandrel into the end region (12). This keeps the load low.

Description

The invention relates to a method for mounting a tubular component of a motor vehicle, in particular a vehicle seat, extending in a longitudinal direction on a further component, which has an opening into which the tubular component is inserted, wherein at least one end region is radially widened for axial form-fitting fastening to the further component. The invention further relates to a component connection between the tubular component and the further component, and to a vehicle seat having such a component connection.In the motor vehicle, especially in vehicle seats, a tubular component, also referred to below as a carrier tube and designed, for example, as a transverse strut or shaft, is frequently connected, for example rotatably, to a further component. The tubular component and the further component are in particular parts of a vehicle seat assembly. An end region of the tubular component is inserted into an opening of the further component. In order to form an axial, positive locking with the further component and thus to form a component connection between the tubular component and the further component, the end region of the tubular component is radially widened. This form-fitting securing also serves in particular as a crash securing means.Alternatively or additionally, securing rings and / or screws are provided, for example, for axially securing the further component to the tubular component.During a forming process, an expanding forming tool is generally pressed into the tubular component in the longitudinal direction, so that the end region of the tubular component is enlarged in diameter to form the axial securing means by the force acting in the longitudinal direction.In conventional forming by means of a conical forming tool pressed in the longitudinal direction, high axial forming forces acting in the axial direction are introduced. It is disadvantageous that these axial forming forces must be supported on a counter bearing. This is often difficult in a more complex assembly, such as a vehicle seat assembly. In particular in the case of thinner and / or longer components, such as a so-called retainer shaft of a vehicle seat, for example, this frequently leads to problems, since the high axial forming forces have to be dissipated via the tubular component and supported on an additional counter bearing attached during assembly. In this case, there is the risk that the tubular component will be damaged and, for example, buckle. Also, the arrangement of a sufficiently dimensioned counter bearing during assembly is frequently difficult. Such a differential shaft usually serves for synchronizing opposing fittings which are mounted for a rotatable connection between a seat frame and a backrest part.Proceeding from this, the object of the invention is to enable an expansion of an end region of the tubular component with at most low axial forming forces.The object is achieved according to the invention by a method for mounting a tubular component of a motor vehicle, in particular a vehicle seat, extending in a longitudinal direction on a further component which has an opening into which the component is inserted. For axial positive locking of the tubular component to the further component, an end region of the tubular component is radially expanded by screwing a forming mandrel into the tubular component and thereby expanding the end region.In the present case, end region is understood to mean the end section of the tubular component that is deformed and widened in the final state.In the initial state, before screwing in, the tubular component preferably has a cross-sectional contour that is constant in the longitudinal direction, for example circular or even non-circular in an end section.Preferably, the forming mandrel is screwed directly into this end section of the tubular component, which then forms the end region expanded in the final state.Alternatively, the forming mandrel is preferably screwed exclusively into a section of the tubular component lying further inwards and thus subsequently to the end region (expanded in the final state).In both cases, such a non-(substantially) formed longitudinal section of the tubular component adjoining the end region has an internal thread at least at the end of the forming process.It should be emphasized that a screwing process is used for the forming process, so that the forming forces required for widening the end region are therefore applied via the screwing process. In contrast to conventional methods for conical widening, in which a forming element is pressed in the axial direction under the exertion of an axial pressing force (axial forming force), such an axial pressing force is just not required, so that overall the load on the component group is low.In a preferred development, it is correspondingly also provided that the forming mandrel is screwed into the component without the action of an axial forming force to be dissipated via the tubular component. This is understood to mean that, by means of a corresponding screwing tool which is used for screwing in the forming mandrel, no axial pressing force is exerted for pressing the forming mandrel into the tubular component, as is the case with conventional forming tools, and which are discharged via the tubular component and are received by a counter bearing.For screwing in the forming mandrel, a certain pressing force can be applied in order, for example, to bring the forming mandrel into engagement with the tubular component for the desired screwing process. However, no axial force exceeding such a pressing force is exerted, which is applied to the forming mandrel from the outside and which would be required for the expansion. The forces required for the widening are applied in particular exclusively by means of the mutual support of the thread flanks during the screwing process. This alternate support of the thread flanks therefore replaces the counter bearing previously required. Since the support is already effected directly in the region of the forming mandrel, the need also arises for axial forces to be dissipated via the tubular component, so that damage to the tubular component is reliably avoided.The forming mandrel preferably has a conical and thus conical widening section which widens the end region conically when screwing in. The geometry of the conical widening section determines the geometry of the end region widened in the final state. The lateral surface of the widening section is preferably smooth.The conical widening section preferably has a cone angle which is, for example, in the range between 30 and 75° and in particular in the range between 40 and 60° and preferably between 35° and 40°. Cone angle is understood in the present case to mean the angle which-viewed in a vertical section perpendicular to the longitudinal direction-assumes the cone lateral surface with respect to a central axis of the cone.In an expedient development, the forming mandrel has a threaded section with which it is screwed into the component. The forming mandrel is therefore a special screwing tool with an external thread, which is suitable for screwing into the component and widening the component.In an expedient embodiment, the threaded section and the conical widening section are formed by partial sections of the forming mandrel which are separated in the longitudinal direction. In particular, the threaded section is arranged leading to the widening section. As a result of this measure, the two functional regions are therefore spatially separated from one another. They preferably adjoin one another directly.In an expedient embodiment, the threaded section is formed on a cylindrical envelope curve. This is understood to mean that the individual thread turns lie on the same (thread) diameter. Only a start of the threaded section can have a chamfer or a so-called tapped cut, by means of which facilitated insertion of the threaded section is achieved. The thread diameter is adapted to an inner diameter of the tubular component in the initial state. In this case, matching is understood to mean that the outer diameter is selected such that the threaded section engages in the component for the screwing process.The individual threads of the thread are designed to be completely circumferential according to a first embodiment variant. According to an alternative embodiment, threaded regions which extend all around over a certain angular range are formed, as viewed in the circumferential direction, and are spaced apart from one another in the circumferential direction. In this case, the threaded section is therefore configured to be segmented in the circumferential direction and, viewed in cross section, overall has a non-round shape; in particular, indentations or longitudinal grooves are formed between the only partially circumferential threaded regions.The tubular component is, for example, a cylindrical tube or alternatively a partially cylindrical tube, which has discrete indentations or bulges on the outer circumference for a connection with the further component in a positively locking and thus rotationally fixed manner in the circumferential direction.Preferably, a forming mandrel with a segmented thread is used in the case of a cylindrical tube and a forming mandrel with a revolving thread is used in the case of a partially cylindrical tube.According to an alternative embodiment variant, the threaded section forms the conical widening section at least partially or else completely. This means that the threaded section also widens conically either completely or at least over a part. In this embodiment variant too, the thread turns are designed to be completely circumferential, for example, or thread areas which are circumferentially circumferentially only in regions are designed.In a preferred embodiment, the threaded section has a self-forming thread which, when screwed into the component, forms the previously described internal thread therein. In this embodiment variant, the tubular component is formed without an internal thread before widening.According to a first variant, this is a self-tapping thread, which therefore cuts into the inner wall of the tubular component, as it were, by machining the thread. Alternatively, only thread forming is effected by a material displacement without machining being effected.In a preferred embodiment, the forming mandrel has a stop which comes to rest against the end region when screwing in, in particular against an end-side end face of the component. By means of the (axial) stop, a screw-in depth and in particular a length of the widened end region is limited and defined. This ensures a defined and in particular positionally accurate widening of the end region.The stop is generally formed following the widening section and is in particular directly adjacent to the latter.In principle, a defined widening of the end region and thus a defined formation of an axial securing means with functionally appropriate and in particular defined tolerance deviations is already achieved by the formation of the widening by means of the screwing process. The stop additionally improves the tolerance accuracy or makes it possible to ensure it in a reliable manner. Depending on the application, for example, a defined axial clearance is set between the widening and the further component, so that an axial displacement of the tubular component within a desired axial clearance is made possible. Alternatively, the widening is specifically formed in such a way that a clearance-free axial securing means is formed.The object is furthermore achieved according to the invention by a component connection between a tubular component and a further component, in particular of a vehicle seat, wherein the further component has an opening into which the tubular component is inserted, wherein an end region of the tubular component is radially widened for axial positive locking on the further component, and the tubular component has an internal thread.The internal thread is only the result of the specific method described here for widening the end region. It therefore does not serve for any other screw fastening and in particular also for forming an axial securing of the tubular component on the further component. Overall, therefore, a screw-free axial securing of the tubular component on the further component is formed. Otherwise, no further axial securing element is preferably arranged or formed next to the widening.In the assembled state, therefore, preferably no screw element is screwed into the formed internal thread. The tubular component is preferably open in the region of the internal thread or is closed, for example, only by a covering cap.The internal thread preferably has a cylindrical internal thread section which adjoins the widened end region. This internal thread section is directly adjacent to the widened end region. It preferably extends only over a part of the tubular component. In particular, its length corresponds to the length of the cylindrical threaded section of the forming mandrel.In a preferred embodiment, the internal thread has, in particular in addition to the cylindrical internal thread section, a conical internal thread section which is formed in the widened end region. Depending on the embodiment variant, the thread and the thread turns are completely circumferential in the circumferential direction (in particular in the case of an originally cylindrical tubular component) or are interrupted in the circumferential direction and have thread regions spaced apart from one another, so that an internal thread segregated in the circumferential direction is formed.According to a preferred embodiment, thread flanks are deformed in this conical internal thread section.Alternatively, according to a preferred development, the inner wall is configured to be smooth in the conically widened end region.Such a configuration-either with a deformed conical internal thread section or even with a smooth inner wall in the end region-is formed in particular by the method described above, in which the forming mandrel is screwed in with a (cylindrical) thread section, which is adjoined by the conical and smooth widening section. During the screwing process, therefore, an internal thread is initially formed in the end section of the component or is already present there, which is subsequently at least deformed or completely smoothed again by the widening. An initially existing internal thread section in the end region is thus re-formed by the widening section.The component connection is in particular part of a motor vehicle, specifically part of a vehicle seat of such a motor vehicle.Furthermore, the tubular component is preferably designed as a rotary shaft which is rotatably mounted on the further component or on another component.The component is preferably a so-called re-liner shaft of a vehicle seat. This connects two opposite side parts of the vehicle seat and is designed in particular for synchronizing the rotational position of covers, by means of which a backrest part is mounted rotatably with respect to a seat frame.According to a first variant, the component is preferably connected to the further component in a rotationally fixed manner. For this purpose, in a preferred embodiment, it is designed to be non-round at the end and in particular also in the end region and has, for example, radial recesses or indentations. Correspondingly, the opening in the further component is also of non-round configuration and has corresponding radial indentations or bulges, so that these two components engage in one another in a positive-locking manner in the circumferential direction for the rotationally fixed connection.According to an alternative, second variant, the tubular component is rotatably mounted on the further component. For this purpose, the tubular component and the opening are preferably round and / or are rotatably mounted on one another via a bearing element. In this variant, the opening forms a bearing opening. The bearing element is in particular a bearing bush, and is arranged between the tubular component and an inner wall of the hole of the further component.The further component is arranged and mounted in particular directly adjacent to the widening, which leads to a compact construction. Due to the high tolerance accuracy of the axial securing means formed by the widening, the further component can be arranged close to this axial securing means and-in the case of a rotatable arrangement-mounted without the risk of difficulty being present.Depending on the variant of the embodiment, the further component is a side part, for example of the seat frame, or also of the backrest part of a vehicle seat. The side parts are usually formed sheet metal parts. Additionally or alternatively, the further component is a fitting element which is fastened, for example, to such a side part and is designed, for example, as a rotary fitting or a latching fitting. Furthermore, the further component can be a lever of a kinematic system, in particular a kinematic system, by means of which a height adjustment or inclination adjustment of a seat part is made possible.The tubular component is usually axially secured in both directions, on the one hand by the widened end region and on the other hand by a further form-fitting axial securing means. This is formed, for example, by an abutment fastened to the tubular component, by a flange or also by a circumferential fold or bulge of the tubular component itself.An exemplary embodiment of the invention is explained in more detail below with reference to the figures, which show in simplified representations: FIG. 1 shows a view of a backrest part of a vehicle seat of a motor vehicle with a differential cylinder fastened thereto and forming a tubular component, FIG. 2 shows an end region of the retrieval shaft, which is guided through an opening of a further component configured as a fitting element, together with a forming mandrel according to a first variant, FIG. 3 shows a perspective illustration of a forming mandrel according to a second variant, FIG. 4 shows a simplified sectional view through the tubular component and through the further component before the end region is formed, and FIG. 5 shows the sectional view according to FIG. 4 after the widening of the end region.FIG. 1 shows a perspective view of a portion of a vehicle seat 1 of a motor vehicle, namely of a component group which comprises a rotatable component connection 2 between a backrest part 3 and a seat frame, wherein only one fitting 5 is illustrated in FIG. 1.In the exemplary embodiment, the component connection 2 is formed between a tubular component 4 and a further component 6 formed as a fitting element. The fitting element is in particular designed in the manner of a pane.The tubular component 4 extends in a longitudinal direction L. The tubular component 4 is designed in particular as a transverse tube forming a shaft (differential shaft). It connects two opposite side parts of the vehicle seat 1 to one another.The tubular member 4 forms a rotary shaft. In the embodiment as a retrieval shaft, it serves in particular for synchronizing the fittings lying opposite. In alternative variants, the tubular component 4 forms, for example, at the same time an axis of rotation about which two seat parts of the vehicle seat can be rotated relative to one another.The further component 6 has an opening 10, through which the tubular component 4 is guided by an end region 12, so that the end region 12 protrudes beyond the further component 6.The tubular component 4 extends generally from an end side of the end region 12 in the longitudinal direction L. In the initial state, the tubular component 4 has a constant outer diameter over its length, for example, and is designed as a hollow tube, in particular a round tube, wherein-as in the present embodiment variant-an end portion of the round tube can be formed into a non-round circumferential contour. Alternatively, the non-round circumferential contour can also be formed over the entire length.This non-round circumferential contour (cf. in particular FIG. 2 ) is formed by a plurality of, in the exemplary embodiment three, radial bulges from the originally round tube. Correspondingly, the opening 10 also has a non-round cross section, in particular with corresponding bulges.For axial securing of the tubular component 4, its end region 12 is flared, as is shown in particular in FIG. 5.For expanding the end region 12, a forming mandrel 14 is used, as is illustrated by way of example in FIGS. 2 and 3.The forming mandrel 14 has in each case a threaded section 16 provided with a thread, which is adjoined-counter to the longitudinal direction L-by a conical and thus conical widening section 18 with a preferably circular cross-sectional area. In the exemplary embodiment, the threaded section 16 has completely circumferential thread turns. Alternatively, the threaded section 16 is configured segmented in the circumferential direction and has individual threaded regions spaced apart from one another in the circumferential direction.Following the widening section 18, an end section 20 is preferably also formed, which is in particular cylindrical.In the embodiment variant according to FIG. 3, a stop 22 is also directly adjacent to the widening section 18. In the exemplary embodiment, this is designed as an annular surface oriented perpendicular to the longitudinal direction L.Preferably, the forming mandrel 14 has, in a direction leading to the threaded section 16, a conical insertion section 24 and, at the opposite end, a tool engagement point 26, in the exemplary embodiment a polygonal bolt, by means of which the forming mandrel can be inserted, for example, into a screwdriver.For widening the end region 12, the forming mandrel 14 is screwed into the end region 12. The end region 12 and in particular the entire tubular component 4 preferably has no internal thread in the initial state.The thread of the threaded section 16 is preferably a self-tapping thread. The forming mandrel 14 is therefore preferably designed as a special thread cutter.When the threaded section 16 is screwed into and screwed into the initially non-widened and threadless end region 12, an internal thread 28 is formed in its inner wall. The forming mandrel 14 is screwed further into the end region 12 in the longitudinal direction L. The widening section 18 widens the end region 12 conically.In the variant according to FIG. 3, the forming mandrel 14 is screwed in as far as the stop 22.The widening and screwing in are preferably effected mechanically and in particular automatically. The stop 22 ensures a process-safe defined widening of the end region 12.The forming mandrel 14 is then unscrewed again and the situation shown in FIG. 5 is obtained with the widened end region 12, in which the internal thread 28 is now formed.Due to the special screwing-in process with the forming mandrel 14 with the leading, in particular cylindrical, threaded section 16 and the trailing widening section 18, a cylindrical internal thread section 28A is formed in this final state in the cylindrical partial region of the tubular component 4 adjoining the end region 12. In the exemplary embodiment, because of the non-cylindrical configuration of the tubular component 4 that is non-circular in the initial state, this is configured to be segmented in the circumferential direction with a plurality of thread regions spaced apart from one another in the circumferential direction. In the widened end region, a conical, likewise segmented, internal thread section 28B adjoins this. However, due to the forces occurring during the widening, this is typically deformed, so that only deformed thread turns are present, as is represented in FIG. 5 by the dotted lines. Depending on the application, there is also the possibility that the internal thread section 28B initially formed in the end region 12 is subsequently pressed back completely flat again by the widening section 18, so that a smooth inner surface is present in the widened end region 12.The particular advantage of the here described embodiment of the axial securing by widening the end region 12 by screwing in the forming mandrel 14 can be seen in the fact that no axial forming forces are exerted on the tubular component 4 and / or the forming mandrel 14, which would otherwise have to be absorbed and conducted away by the component group. The widening of the end region 12 therefore takes place in particular without axial force support on a counter bearing.List of reference characters1 Vehicle seat 2 Component connection 3 Backrest part 4 Tubular component 5 Fitting 6 Further component 10 Opening 12 End region 14 Forming mandrel 16 Threaded section 18 Widening section 20 End section 22 Stop 24 Introduction section 26 Tool attachment 28 Internal thread 28A Cylindrical internal thread section 28B Conical internal thread section L Longitudinal direction

Claims

Method for mounting a tubular component (4) of a motor vehicle, in particular a vehicle seat, extending in a longitudinal direction (L) on a further component (6) which has an opening (10) into which the tubular component (4) is inserted, wherein an end region (12) of the tubular component (4) is radially expanded for axially positively securing the tubular component (4) on the further component (6), characterized in that, for radially expanding the end region (12), a forming mandrel (14) is screwed into the tubular component (4) and in particular into the end region (12), and the end region (12) is expanded in the process.Method according to the preceding claim, characterized in that the forming mandrel (14) is screwed into the tubular component (4) without the action of an axial forming force to be dissipated via the tubular component (4).Method according to one of the preceding claims, characterized in that the forming mandrel (14) has a conical widening section (18) which widens the end region (12) conically when screwing in.Method according to one of the preceding claims, characterized in that the forming mandrel (14) has a threaded section (16), with which it is screwed into the tubular component (4).Method according to the preceding claims, characterized in that the threaded section (16) is arranged leading to the widening section (18).Method according to one of Claims 4 to 5, characterized in that the threaded section (16) is formed on a cylindrical envelope curve.Method according to one of Claims 4 to 6, characterized in that the threaded section (16) has a self-forming thread which, when it is screwed into the tubular component (4), forms an internal thread (28) therein.Method according to one of the preceding claims, characterized in that the forming mandrel has a stop (22) which comes to bear against the end region (12) when screwing in.Component connection (2) between a tubular component (4) extending in a longitudinal direction (L) and a further component (6), in particular of a vehicle seat, wherein the further component (6) has an opening (10) into which the tubular component (4) is inserted, wherein an end region (12) of the tubular component (4) is radially widened for axial positive locking to the further component (6), characterized in that the tubular component (4) has an internal thread (28).Component connection (2) according to the preceding claim, in which a screw-free axial securing means is formed between the tubular component (6) and the further component (6).Component connection (2) according to one of the two preceding claims, in which the internal thread (28) has an internal thread section (28A) with a diameter which remains the same in the longitudinal direction, wherein the internal thread section (28A) adjoins the widened end region (12).Component connection (2) according to one of Claims 9 to 11, in which the internal thread (28) has a conical internal thread section (28B) in the end region (12).Component connection (2) according to one of Claims 9 to 12, in which the tubular component (4) is a rotary shaft which is rotatably mounted on the further component (6) or on another component.Component connection (2) according to one of claims 9 to 13, in which the tubular component is connected to the further component (6) in a rotationally fixed manner and the tubular component (4) is preferably designed to be non-round at the end for this purpose and the opening is likewise designed to be non-round.Vehicle seat having a component connection (2) according to one of Claims 9 to 14.

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