WO2012065982A1 - Method for producing a threaded spindle and threaded spindle for adjusting devices in motor vehicles - Google Patents

Abstract

Method for producing a threaded spindle 3 for an adjusting device in a motor vehicle, comprising a threaded portion 30, end stops 31 on the threaded portion for limiting the adjusting travel of the adjusting device and fastening portions 32 with fastening flanges 35 and fastening openings 36. The end stops of the threaded spindle 3 are formed by upsetting a collar 31. Increased strength and better quality of the surface of the fastening portion 32 are achieved by plastically changing the cross-sectional shape by forming a profile 6 onto at least part of the fastening portion 32 by means of cold working. To increase further the strength and load-bearing capacity of the fastening portion 32, the profile 6 is fashioned with a cross section that increases the section modulus of the fastening portion 32 in the direction of the bending and buckling loading of the threaded spindle 3 and the profile 6 is aligned in such a way that the greatest cross-sectional length coincides with the direction of the main loading of the fastening portion 32 of the threaded spindle 3.

Description

 Method for producing a threaded spindle and threaded spindle for

 Regulating devices in motor vehicles

description

The invention relates to a method for producing a threaded spindle for adjustment devices in motor vehicles according to the preamble of claim 1 and a threaded spindle for adjustment devices in motor vehicles according to the preamble of claim 16.

From DE 100 45 806 A1 a seat longitudinal adjustment for a motor vehicle seat with two elongated, mutually adjustable in the rail longitudinal direction seat rails, a seat rails along the rail longitudinal adjustment mutually adjusting adjusting device and a threaded spindle is known, which is rotatably connected to one of the two seat rails. The ends of the threaded spindle have an integrally formed by forming the mounting flange, which is also integrally provided with an attachment point, via which the threaded spindle is connected to the associated seat rail. The attachment point is formed by a fastening opening, which is generated in the mounting flange by cutting and in particular by punching.

From DE 10 2004 001 624 B3 a drive of a seat adjustment device for a motor vehicle with a spindle is known, which is attached to a first of two relatively adjustable rails by means of end located on the spindle mounts, while a driven by a motor gearbox is arranged on the second rail. The L-shaped brackets have a plate-shaped, horizontal leg, in which a mounting hole is incorporated, which connects the brackets by means of screw or rivet connections via the first rail to the vehicle floor. The vertical leg of the L-shaped brackets is designed as a solid, block-like part, on top of which a trough-like depression is provided, which serves as a support surface for one end of the spindle. To connect the spindle ends of the trough-like depressions of the brackets they are attached on both sides each with a weld. Furthermore, the holders have a flat stop surface. che, which connects the lower support surface with the upper, trough-like support surface and serves as a stop for the transmission in end positions of the seat adjustment. In the known spindle drive, the spindle and the brackets are formed with the end stops as separate parts, which must be connected to each other by an additional joining process in the form of welded joints. This requires an additional machining process and due to the welded joints weak points that reduce the durability and in particular the durability and strength in the event of a crash.

Under heavy load, especially in the event of a crash, there is also the risk of buckling of the threaded spindle in the region between the threaded portion or the end stop of the threaded spindle and the holder or the mounting flange for connecting the threaded spindle with one of the relative to each other to be adjusted parts adjusting device. An increase in the load capacity of threaded spindles by cross-sectional enlargement or use of higher loadable material is associated with an increased production cost and a modification of conventional threaded spindle configurations, which also lead to an increased effort in the production of adjusting devices with threaded spindles.

From DE 10 2004 001 593 B3 it is known to form the spindle thread facing the front side of the holder as a stop surface for the transmission in order to limit the travel of the transmission. To produce the holder, a solid, defined cut-to-length wire is cold-formed into a blank in a pear shape in one step, so that the blank has a compressed area with an approximately oval cross-section over approximately half of its length. Following a transition region, the blank has the original, cylindrical shape over the other half of its length. In a second step, the blank is placed in a tool, the die determines the shape of the support for receiving the threaded spindle and the mounting flange, while the stamp defines the flat contact surface of the holder. With the pressing of the blank is the holder with its final outer contour. In a third step, the attachment opening is punched out. In a one-piece design of threaded spindles with a spindle with integrated brackets and attachment points and end stops, it is known to attach the spindle thread by machining to a cylindrical blank, with a collar stops as an end stop. For this purpose, however, it is necessary to size the diameter of the blank according to the required diameter of serving as an end stop federal and herauszuarbeiten the thread accordingly, so that the end stop is the measure of the thickness of the blank or semi-finished and the rest of the threaded spindle of a thicker semi-finished, which reduces the spindle properties, increases the weight of the spindle and requires additional manufacturing effort.

As a further alternative, it is known to provide the limitation of the adjustment of an adjusting device in motor vehicles not by an end stop on the threaded spindle itself, but to arrange a separate stop on the device to be adjusted, such as a vehicle seat by lever or bracket.

The object of the present invention is to provide a method for producing threaded spindles and a threaded spindle for adjusting devices in motor vehicles, which ensure a high degree of strength, in particular a high load capacity in the event of a crash, with low production costs, while maintaining conventional threaded spindle configurations.

This object is achieved by a method with the features of claim 1 and by a threaded spindle with the features of claim 16 solves.

The solution according to the invention, while maintaining conventional threaded spindle configurations, ensures high strength of threaded spindles with low production outlay, in particular a high load capacity of the fastening section of threaded spindles between their threaded section and mounting flange, even in the event of a crash.

The plastic change in the cross-sectional shape of at least part of the fastening section results in cold working, which during the plastic deformation leads to an increased dislocation density with work hardening and thus to increased strength and better surface quality of the fastening section leads and can be done by rolling, rolling, embossing, molding a profile of the usually rotationally symmetric blank by means of pressing or pressing tools.

Preferably, a profile is formed on the geometry of the fastening section and in particular impressed for the plastic change of the cross-sectional shape of the part of the fastening section, as a result of the work hardening the mechanical properties of the base material are changed by the strength is increased compared to the non-deformed geometry of the mounting portion. By using profiles with different cross-sections, the strength of the mounting portion can be controlled according to a further feature of the invention, since the respective profile determines the degree of cold working and increases the strength of the mounting portion with the degree of deformation. To further increase the strength and load capacity of the attachment portion, the profile is embossed with a resistance moment of the attachment area in the direction of bending and buckling load of the threaded spindle increasing cross-section, wherein the profile is aligned with respect to the vehicle floor, that the largest cross-sectional length with the direction the main load of the Befestigungsab- section of the threaded spindle coincides.

By increasing the profile perpendicular to the bending or bending line of the threaded spindle and thus perpendicular to the main loading direction of the threaded spindle, the moment of resistance of the loading section is increased, wherein the height is quadratic in the determination of the resisting torque, so that an orientation of the profile in the direction of greatest stress the threaded spindle or its attachment portion gives the maximum moment of resistance of a particular profile of the attachment portion. To increase the compressive or tensile load of the threaded spindle ribs can be formed in a further development of the present invention to a part of the transition region of the mounting portion, wherein the transition region is formed with an aligned with the threaded portion of the threaded portion and a part of the mounting flange, bent part and the ribs are impressed on the side edges of the bent flange part of the transitional area passing into the fastening flange and run off into the fastening flange. Before molding or embossing a profile on a part of the fastening portion, the blank of the threaded spindle can be upset between the threaded portion and the mounting portion of the threaded spindle to form a collar serving as an end stop for the adjustment of the adjusting device, wherein the upsetting of the collar and the profiling of the fastening portion done in a tool with appropriately trained die for the federal government and the profile of the attachment section. To ensure a minimum of machining steps and tools in the manufacture of a threaded spindle with integrated limit stops with maximum strength and durability properties, the end stops of the threaded spindle are formed by upsetting a federal government. Forming end stops of the threaded spindle by upset of a federal government, allows a minimum of machining steps and tools in the manufacture of the threaded spindle and provides threaded spindles with integrated end stops with the greatest possible strength and durability properties, so that

 no separate production of the spindle part of the threaded spindle and of an end stop, which are to be connected to one another in an additional joining process, no machining operation for attaching an end stop,

 - No separate from the threaded spindle arrangement of separate stops on the device to be adjusted and

 no diameter of the blank or semi-finished product of the threaded spindle determined by the diameter of the end stop

required are.

In addition, the formation of end stops of the threaded spindle by upsetting a collar enables the integration of the end stop into a tool that can be used for further processing steps, so that additional forming tools can be saved.

Preferably, the starting diameter of the semi-finished product of the threaded spindle is smaller than the tip circle of the thread of the threaded spindle, which is attached after the upsetting of the federal instrument, so that with minimal material use attaching the thread and serving as an end stop federal and thus can be produced with minimal time and effort.

The method of forming the end stops of the threaded spindle by upsetting a bundle against the blank or semifinished product can be realized in different ways by:

 the collar is poked in the same tool before further machining processes of the threaded spindle,

 - the collar is puffed up separately and the pressed blank is subsequently machined in further machining processes, such as reshaping, joining or machining, for attaching the threaded section of the threaded spindle, the fastening section or fastening sections and the fastening point (s) or

 In a first processing step, the fastening portion or the fastening portions are formed on the blank of the threaded spindle, that in a second processing step, the collar of the threaded spindle and the pressed blank in further processing steps such as forming, joining, drilling or machining for attaching the threaded portion of the Threaded spindle and the attachment points is processed.

The fastening sections have at the end the fastening flanges with the fastening points, preferably designed as fastening openings, which are produced either in further machining processes or during the shaping of the fastening sections or mounting flanges.

Since under heavy load, especially in the event of a crash, the risk of buckling of the threaded spindle in the region between the threaded portion or the end stop of the threaded spindle and the holder or the mounting flange for connecting the threaded spindle with one of the relative to each other to be adjusted parts of the adjusting device, a Increasing the load capacity of a threaded spindle by a cross-sectional enlargement or use of a higher load capacity with increased manufacturing costs and a modification of conventional threaded spindle configurations is connected, the threaded spindle is formed according to a further feature of the invention from a cylindrical blank and the cross-sectional shape of at least a portion of the mounting portion of the threaded spindle changed plastically. This ensures a high strength of the threaded spindle with low production costs, while maintaining usual threaded spindle configurations, in particular a high load capacity of the fastening portion of the threaded spindle between the threaded portion and mounting flange in the event of a crash.

The one-piece design of the spindle, collar and mounting sections ensures a safe transmission of forces in the event of a crash. The above-solving threaded spindle for adjustment devices in motor vehicles with a threaded portion and a mounting portion containing a mounting flange with a mounting hole for receiving a threaded spindle to the vehicle floor connecting fastener and a transition region between the threaded portion and the mounting flange, according to the invention at least a non-rotationally symmetrical profile, which can be configured as a square profile, an oval profile, a triangular profile or a cross-shaped profile, forms part of the fastening section.

By molding and in particular embossing a profile while maintaining the threaded spindle high rigidity of the threaded spindle with low production costs, in particular a high load capacity of the fastening portion between the threaded portion and the mounting flange of a threaded spindle ensured even in the event of a crash, wherein the plastic change of the cross-sectional shape cold forming takes place, which leads during the plastic deformation to an increased dislocation density with a work hardening and thereby to an increased strength of the mounting portion.

In this case, the respective profile of the fastening portion of the threaded spindle can be aligned so that the largest cross-sectional height has in the main loading direction of the threaded spindle, so that a maximum modulus is achieved depending on the profile.

In a further refinement of the profiling of the fastening section of the threaded spindle, when a square profile is impressed, a part of the transitional region which is aligned with the threaded section of the threaded spindle can form a square profile with a substantially constant cross section and a flange which extends into the fastening flange. cranked part of the transition region have a square profile with decreasing height up to the thickness of the mounting flange and up to the width of the mounting flange of increasing width, wherein one of the diagonal of the square profile is aligned in the main loading direction of the threaded spindle.

An oval profile can be produced by embossing parallel sides and area- and kreissektorför-miger upper and lower sides.

When embossing a triangular profile whose cross-section is preferably formed by an isosceles triangle whose Seitenhalbierende between the even-length legs is aligned in the main loading direction of the threaded spindle.

So that when stamping a cross-shaped profile on the mounting portion in the plastic deformation does not occur too high dislocation density in the vertices of the cross structure, the cross-shaped profile has part-circular grooves.

As an alternative or in addition to embossing a profile on the fastening section, the profile may consist of two ribs integrally formed on the side edges of the transitional region of the fastening section, between which a channel-shaped depression is formed, the ribs being bent over to the side edges of the bent-over flange Part of the transition area are formed and leak into the side edges of the mounting flange. In the following the invention will be explained in more detail with reference to several embodiments shown in the drawing. Show it:

Figure 1 is a schematic-perspective exploded view of an adjusting device for a motor vehicle seat with relatively adjustable upper and lower rail, connected to the upper rail adjustment drive with a spindle nut and connected to the lower rail threaded spindle with integrated end stops. an end portion of a threaded spindle with a threaded portion, an end stop serving as an integrally formed collar and a Befestigungsab- cut with cranked, cylindrical transition area and flat mounting flange; a perspective view of an end portion of a threaded spindle with a mounting portion with an impressed square profile; a cross section through a mounting portion with embossed square profile; 5 shows a cross section through a mounting portion with embossed oval profile.

6 shows a cross section through a mounting portion with embossed oval profile and alignment of the largest axis in the main loading direction.

7 shows a cross section through an attachment section with an impressed isosceles triangular profile and alignment of the side bisectors in the main loading direction; 8 shows a perspective view of the end region of a threaded spindle with an impressed, cross-shaped profile of the fastening section; a cross section through the cross-shaped profile of FIG. 8; 10 is a perspective view of a threaded spindle formed by upsetting a federal end stops. a schematic-perspective view of a tool for the produc- tion of a threaded spindle with out by upsetting a federal formed end stops; a perspective longitudinal section through the tool of FIG. 1 1;

Fig. 13-16 is a schematic representation of the process steps for the preparation of

Threaded spindle with end formed by upsetting a collar striking and integrated in a tool machining process for the preparation of the mounting flange;

17 is a perspective view of an end portion of a threaded spindle with a threaded portion, an upset collar to form an end stop of the adjustment of an adjusting device, an impressed square profile in the transition region of the attachment portion and a groove profiling of the mounting flange and Fig. 18 is a perspective view of an end portion of a threaded spindle formed on the side edges of the bent portion of the mounting portion, the mounting flange expiring ribs.

1 shows a schematic perspective exploded view of an adjustment device for the longitudinal adjustment of a motor vehicle seat with rails 1, 2, which are adjustable relative to one another, of which an upper rail 1 is connected to the motor vehicle seat, while a lower rail 2 is fastened to the vehicle floor. The lower rail 2 comprises a base surface 20 with mounting holes not shown for attachment to the vehicle floor and two upwardly projecting from the base surface 20, de integrally molded side parts 21, 22, at the free ends of each guide and Verhakungsbereiche are formed. By means of these guide and hooking areas 21, 22, the engagement with the upper rail 1 can be produced, which is connected to the lower rail 2 with guide and hooking areas arranged on the side parts 11, 12 and movable in the longitudinal direction relative to the lower rail 2.

As drive for the longitudinal adjustment of the upper rail 1 in the lower rail 2 is a spindle drive with a threaded spindle 3 which is rotatably attached to the lower rail 2 and has a threaded portion 30 on which a spindle nut 40 of a spindle gear 4 is rotatably mounted and longitudinally displaceable. The spindle nut 40 of the spindle gear 4 is driven by a drive motor, not shown, which is connected via a drive shaft to the spindle gear 4, the connection to the upper rail 1 via mounting holes 13, 14 in the upper rail 1 and fasteners 41, 42 on the housing 45 of the Spindle gear 4 takes place. For attachment of the threaded spindle 3 to the lower rail 2, the threaded spindle 3 at its ends mounting portions 32 with end mounting flanges 35th on, which abut directly on the surface of the lower rail 2 or formed out of the base surface 20 of the lower rail 2 mounting brackets. In the mounting flanges 35 provided mounting holes 36 are aligned with associated openings in the base surface 20 of the lower rail 2 and in the bearing blocks of the lower rail 2. Through the mounting holes 36 through the threaded spindle 3 and the lower rail 2 can be assigned via suitable fastening means such as screws with Nuts or rivets are joined together.

The flat mounting flange 35 is crushed and is bent relative to the central axis of the threaded spindle 3 when it is attached to the base surface 20 of the lower rail 2. Furthermore, the attachment portions 32 include a transition region 33, 34, which consists of a aligned with the threaded portion 30 of the threaded spindle 3 cylindrical portion 33 and a transition into the mounting flange 35, bent portion 34, so that the mounting flange 35 flush and flush with the the vehicle floor connected base surface 20 of the lower rail 2 or formed in the lower rail 2 bearing block rests.

To limit the adjustment of the adjusting device by end stops, which also complete the threaded portion 30 of the threaded spindle 3, a collar 31 is integrated into the threaded spindle 3 on both sides, which was formed from the blank or semi-finished the threaded spindle 3 by upsetting. For this purpose, the starting diameter of the semifinished product or blank of the threaded spindle 3 was smaller than the tip circle of the threaded portion 30 of the threaded spindle 3 dimensioned and attached after the upsetting of the federal in a tool, the thread of the threaded portion 30 on the threaded spindle 3 in a joining process or cutting process.

Fig. 2 shows a perspective view of the end portion of the threaded spindle 3 with a cylindrical threaded portion 30, the thread meshes with the spindle nut 40. To limit the adjustment, the threaded spindle 3 has a trained as a collar 31 end stop, which has been aufgestaucht in a preferred embodiment of the blank of the threaded spindle 3 and thus an integral part of the threaded spindle 3.

In order to connect the threaded spindle 3 to the lower rail or the vehicle floor, the threaded spindle 3 has a fastening section 32, which contains a planar fastening flange 35 with a fastening opening 36 through which a fastening tion element in the form of a rivet or a screw inserted and connected to the lower rail or the vehicle floor, in particular screwed, is. The flat mounting flange 35 is crushed and is bent relative to the central axis of the threaded spindle 3 when it is attached to the base surface 20 of the lower rail 2.

Furthermore, the attachment portion 32 includes a transition region 33, 34, which consists of a aligned with the threaded portion 30 of the threaded spindle 3 cylindrical portion 33 and a merging into the mounting flange 35, bent portion 34, so that the mounting flange 35 flush and flush with the the vehicle floor connected base surface 20 of the lower rail 2 or formed in the lower rail 2 bearing block rests.

Since the area between the attachment opening 36 and the collar 31 is exposed to considerable bending and buckling loads when actuating the adjustment device, for example for the longitudinal adjustment of a motor vehicle seat, the attachment section 32 must have a correspondingly high strength in order to meet the high stresses during normal operation. In the event of a crash, due to the dynamic forces, even greater bending and bending forces act on the fastening section 32 of the threaded spindle 3, so that corresponding material properties of the fastening section 32 integrated in the threaded spindle 3 and / or material cross sections are required.

On the one hand, the geometry of the threaded spindle 3 and in particular its cross section not to change, so that the cramped, available for the adjusting device space is sufficient and on the other hand no production effort increasing material selection is to make is to the transition region 33, 34 a profile. 6 10 imprinted, which changes the cross-sectional shape of the transition region 33, 34 plastically and cold forming with appropriate strain hardening of the transition region 33, 34 causes. The dislocation density which increases during the plastic deformation during the embossing of the profile 6 - 10 leads to an increase in the yield strength and strength of the transition region 33, 34 and thus without an increase in cross-section and / or selection of a material of higher strength to an improvement of the mechanical properties of the base material over the undeformed base material as a result of cold work hardening associated with cold forming. 3 is a perspective view of a transition region 33, 34 with an impressed square profile 6, which is in the part aligned with the threaded section 30 33 has a substantially constant cross section, while in the bent into the mounting flange 35, bent portion 34, the square profile decreases in height to the thickness of the mounting flange 35 and increases in width to the width of the mounting flange 35.

Further embodiments for a cold forming of the transition region 33, 34 for increasing the bending and buckling strength of the transition region 33, 34 are shown in FIGS. 5, 7, 17 and 18 and are explained in more detail below.

In order to increase the strength of the fastening portion 32 against the loads, in particular in the event of a crash and to improve the bending and buckling strength, the surface resistance torque is additionally improved by a corresponding embossing of the fastening portion 32, in particular in the transition region 33, 34 in the direction of the main load of the threaded spindle 3 by increasing the profile 6 - 10 perpendicular to the bending or crease line.

As resistance moment a resistance is defined, which a body opposes a bending or torsional moment, which is caused by a force acting perpendicular to the moment axis on the body.

The magnitude of the moment of resistance results solely from the geometry of the cross-sectional area and, in the case of solid profiles, is proportional to the product of the width of the cross-sectional profile and the square of the height of the cross-sectional profile. For example, for a rectangle with the width b and the height h, a resistance moment W with respect to the horizontal axis b * h ² applies

W _x = -

6 In the same way, the area moment of inertia depends only on the geometry of the cross section, while in contrast the modulus of elasticity provides information about material properties. Among other things, the area moment of inertia provides information about the inclination of bars for buckling. With the area moment of inertia, a stress distribution due to bending over a cross section can be calculated and results as an integral over the product of the square of the square and the area element.

In practice, area moment of inertia and moment of resistance in the area of the linear elastic deformations are relevant. For the technical consideration, especially the moment of resistance is of importance. It takes into account not only the area moment of inertia but also the distance from the neutral fiber of a cross section in which neither compression nor tensile stresses occur in pure bending, to the edge fiber, the maximum vertical distance to the cross-sectional edge, so that on the comparison with the maximum voltage, the allowable stress of a Body can be considered.

4, the effect of the orientation of an embossed square profile 6 according to FIG. 3 will be explained:

Wird dagegen die Diagonalen d des Vierkantprofils 6 in Richtung der Belastung durch eine Kraft F ausgerichtet, so gilt wegen der geometrischen Beziehung d² = 2 a² und dem entsprechend d³ = 2 a³

ein um den Faktor höheres Widerstandsmoment. Für eine praktische Anwendung weiterhin geeignet ist ein angeprägtes ovales Profil 7, das gemäß Fig. 5 aus zwei parallelen Seitenflächen 71 , 72 und kreissektorförmigen O- ber- und Unterseiten 73, 74 zusammengesetzt ist, wobei in Fig. 5 zum Vergleich ein im Querschnitt kreisförmiges Zylinderprofil des Befestigungsabschnitts 32 strichpunktiert darstellt ist. For a square with the side length a, the resistance moment Wy or Wz with respect to the horizontal axis y or the vertical axis z is:

If, on the other hand, the diagonal d of the square profile 6 is aligned in the direction of the load by a force F, then due to the geometric relationship d ² = 2 a ² and the corresponding d ³ = 2 a ³

a resistance factor that is higher by a factor. Also suitable for a practical application is an embossed oval profile 7, which according to FIG. 5 is composed of two parallel side surfaces 71, 72 and sector-shaped upper and lower sides 73, 74, wherein in FIG. 5 a cross-sectionally circular one is shown in FIG Cylinder profile of the mounting portion 32 is shown in phantom.

Analogous to the orientation of the square profile in the loading direction F to increase the moment of resistance of the fixing portion 32 determining moment of inertia of the impressed oval profile shown in FIG. 5 is rotated according to the schematic representation of FIG. 6 in the direction of maximum stress F, which at an angle α acts on the threaded spindle and thus on the mounting portion 32, so that the longest diagonal 75 of the oval profile 7 is aligned in the direction of maximum load F. 7 shows a cross section through an isosceles triangular profile 8 embossed on the fastening section 32 with the base surface 80 and the legs 81, 82 of equal length and width b at the bending or bending line x - x and the height h from the bending or bending line x - x to the intersection of the legs 81, 82. To increase the resistance moment the triangular profile 8 is rotated in the direction of the force acting on the threaded spindle and thus on the mounting portion 32 at an angle α load F, This results in an area moment of inertia Ix with respect to the bending or crease line x - x of

8 shows, in a perspective view of the end region of a threaded spindle 3, the work hardening of the fastening section 32 by embossing a cross-shaped profile 5 which is symmetrical in the longitudinal and transverse direction in the part 33 of the transitional region 33, 34 which is aligned with the threaded section 30 of the threaded spindle 3. is formed and in which merges into the mounting flange 35, bent portion 34 of the transition region 33, 34 of the mounting portion 32 merges with decreasing height or increasing width in the mounting flange 35.

To the dislocation density in the plastic deformation of the mounting portion 32, especially in the aligned with the threaded portion 30 portion 33 is not too strong To increase and thereby reduce the strength of the mounting portion 32 again, has the cross-shaped profile 9 of FIG. 12 between the peripheral ends 91 to 94 of the cross-shaped webs formed circular sector-shaped grooves 95 to 98.

Since the area moment of inertia provides information on the inclination of bars for buckling and its size depends only on the geometry of the cross section (for example, the area moment of inertia for solid profiles is proportional to the product of width of the cross section profile and the square of the height of the cross section profile), is with the area moment of inertia a stress distribution can be calculated as a result of bending over a cross section and results as an integral over the product of the square of the square and the surface element.

In order to increase the strength of the fastening section 32 with respect to the loads, in particular in the event of a crash, and to improve the bending and buckling strength, the surface resistance moment and the area moment of inertia are additionally increased by a corresponding embossing of the fastening section 32, in particular in the transition area 33, 34 in the direction of the main load Threaded spindle 3 improved by the profile is increased perpendicular to the bending or bending line.

Thus, the bending and buckling strength of the attachment portion 32 is increased in the case of the impressed to the transition region 33, 34 of FIG. 4 square profile 6 that not the sides of the Verkantprofils 6 in the direction of the main load force of the threaded spindle 3 during adjustment or in the event of a crash, but the diagonal of the square profile 6 is aligned in the direction of the main load force, since this results in a factor higher resistance moment.

Fig. 10 shows an enlarged perspective view of one of the ends of the threaded spindle 3 with the threaded portion 30, serving as an end stop of the threaded spindle 3, produced by upsetting collar 31, the mounting flange 35 therein mounting hole 36 and one between the collar 31 and the mounting flange 35 provided transition portion 32 which is composed of a subsequent to the collar 31, aligned with the threaded portion 31 cylindrical portion 33 and a bent portion 34, which merges into the mounting flange 35. The upsetting of the collar 31 on a blank or semi-finished product and the further machining processes can preferably be carried out in one tool, but if necessary also in different tools, by

 - The collar 31 is popped before further machining processes of the threaded spindle 3 in the same tool,

 the collar 31 is then puffed up separately and the pressed blank is subsequently used in further machining processes, such as reshaping, joining or machining, for attaching the threaded section 30 of the threaded spindle 3, the fastening section 32 or the fastening sections 32 and the fastening section (s)

36 is processed or

 - In a first processing step, the mounting portion 32 and the mounting portions 32 are integrally formed on the blank of the threaded spindle 3, that in a second processing step, the collar 31 of the threaded spindle 3 and the compressed blank in further processing steps like

Forming, joining, drilling or machining for attaching the threaded portion 30 of the threaded spindle 3 and the attachment points 36 is processed.

In FIGS. 1 1 and 12, a pressing tool 5 for producing the threaded spindle 3 with an upset collar 31 is shown in a perspective view and in a perspective longitudinal section. The two-part pressing tool consists of a punch 51 and a collet 52, which for upsetting the collar 31 and molding the mounting flange 35 with a transition region 33, 34 to the collar 31 and end stop from a spaced apart position for inserting a semifinished product or blanks in axial direction are pushed together.

The punch 51 of the pressing tool 5 has a cylindrical longitudinal bore 50 with a diameter D1 and a cylindrical recess 55 on its end face 58 facing the collet 52, which corresponds to the negative shape of the collar 31 of the threaded spindle 3 to be picked up and has a diameter of the collar 31 corresponding diameter D2 has.

The collet 52 consists of a cylindrical or conical, radially slotted sleeve with a punch 51 facing the end face 59 and offset by 90 ° to each other slots 53, 54 and a centrally extending longitudinal bore 56 with a diameter D3, which is smaller than the diameter D1 the cylindrical longitudinal bore tion 50 of the punch 51. The longitudinal bore 56 is formed either as a blind hole or according to the dashed representation as a through hole. When forming the longitudinal bore 56 as a blind hole, the end of the bore has a flat extension 57, which corresponds to the negative shape of the mounting flange 35.

For collet 52 includes a collet receiving not shown with a suitable collet 52 inner cone, so that by tightening a nut the collet 52 pushes into the inner cone of the collet receiving and thus clamped inserted into the longitudinal bore 56 workpiece or a blank.

The production of a threaded spindle 3 with an upset collar 31 and a mounting flange 35 will be explained with reference to the processing phases shown in FIGS. 13 to 16.

To produce the threaded spindle 3, the punch 51 and the collet chuck 52 are separated from each other in a first processing step and, according to FIG. 13, a solid, cylindrical blank 300 is inserted into the mutually aligned longitudinal bores 50, 56 of the punch 51 and the collet chuck 52. With continuously formed longitudinal bore 56 of the collet 52, the collet 52 is clamped for clamping the blank 300 in the manner described above. If the longitudinal bore 56 of the collet 52 is formed as a blind hole, the end face of the blank 300 abuts against the hole end. Furthermore, the blank 300 is clamped in the punch 51 by means of a clamping device or a pressing device is brought to the end of the blank 300.

In a second processing step, either the punch 51 connected to the blank 300 and the collet chucking the blank 300 or receiving it in its blind bore are moved relative to one another until the end face 58 of the punch 51 abuts against the end face 59 of the collet chuck 52 or one Force exerted on the punch-side end face of the blank 300. Due to the associated pressing operation, the collar 31 is plunged as shown in FIG. 14 within the matrix formed by the cylindrical recess 45. Since the diameter D1 of the longitudinal bore 50 of the punch 51 is greater than the diameter D3 of the longitudinal bore 56 of the collet 52, the portion 301 of the pressed blank provided for the threaded portion 30 has a larger diameter than that of the attachment portion forming section 302, so that in a later, separate processing step, a thread on the portion 301 can be formed.

If the longitudinal bore 56 of the collet 52 is formed as a blind hole, is formed with the pressing of the mounting flange 35 of FIG. 15 in the flat recess 57 of the collet 52 and the transition region 33, 34 formed between the collar 31 and the mounting flange 35.

After the upset of the collar 31 and optionally molding of the mounting flange 35 of the punch 51 and the collet 52 are separated and the threaded spindle 3 with the now molded collar 31, the shape of the recess 55 of the punch 51 and the optionally molded mounting flange 35th taken from the tool 5 for further processing. In further processing steps, the attachment opening 36 as shown in FIG. 16 is punched, punched or drilled in the fastening flange 35 and a thread is formed on the threaded section 30 of the threaded spindle 3.

Since the area between the attachment opening 36 and the collar 31 is exposed to considerable bending and buckling loads during actuation of the adjustment device, for example for the longitudinal adjustment of a motor vehicle seat, the attachment section 32 must have a correspondingly high strength in order to meet the high stresses in normal operation. In the event of a crash, due to the dynamic forces, even greater bending and bending forces act on the fastening section 32 of the threaded spindle 3, so that corresponding material properties of the fastening section 32 integrated in the threaded spindle 3 and / or material cross sections are required.

In order on the one hand not to change the geometry of the threaded spindle and in particular its cross-section, so that the limited space available for the adjustment device is sufficient and, on the other hand, no production effort increasing material selection is to be made, a profile is impressed on the transition region 33, 34. which plastically changes the cross-sectional shape of the transitional region 33, 34 and effects cold working with appropriate strain hardening of the transitional region 33, 34. The dislocation density which increases during the plastic deformation during the embossing of the profile leads to an increase in the yield strength and strength of the transitional region 33, 34 and thus without an increase in cross-section and / or selection of a material of higher strength to an improvement of the mechanical properties. of the base material compared to the undeformed base material due to the work hardening associated with cold working.

Here, the so-called "degree of deformation" is a deformation parameter with which the permanent geometric change of a workpiece during the forming process can be detected.

Fig. 17 shows a perspective view of a mounting portion 32, at its aligned with the threaded portion 30 of the threaded spindle 3 part 33 a square profile 6 is stamped, while the transition into the mounting flange 5 and optionally bent part 34 includes an embossed bead 100 which as well the embossed square profile 6 of the part 33 of the transition region 33, 34 causes a cold work hardening caused by cold forming and thus increasing the strength of the attachment portion 32. The planar fastening flange 35 is shown in section in this representation and shows a fastening element 15 inserted into the fastening opening in the form of a fastening screw whose bearing surface is arranged exclusively in the region of the planar surface of the fastening flange 35.

A further exemplary embodiment for a cold forming of the transition region 33, 34 for increasing the bending and buckling strength of the transitional region 33, 34 is shown in FIG.

Fig. 18 shows a perspective view of the end portion of a threaded spindle 3 with a threaded portion 30 and a mounting portion 32 and a see see arranged collar 31 as an end stop to limit the adjustment of the adjustment with a aligned with the threaded portion 30 portion 33 of the transition region 33, 34th the fastening portion 32, which is cylindrical in this embodiment. The part 34 of the transitional region 33, 34 of the fastening section 32 which transitions into the fastening flange 35 and which is bent depending on the design of the support of the fastening section 32 on, for example, the base surface of a bottom rail or a bearing block, has a rib-shaped profile 10 of two at the side edges of the bent part 34 molded ribs 101, 102, between which a groove-shaped recess 103 is formed. The ribs 101, 102 run parallel to the side edges of the bent part 34 and, in the region of the fastening flange 35, merge into the upper side of the fastening flange 35, so that the groove-shaped depression 103 extends toward the fastening opening 36. farther and the ribs 101, 102 leak into the side edges of the mounting flange 35.

LIST OF REFERENCE NUMBERS

1 upper rail

 2 bottom rail

 3 threaded spindle

 4 spindle gear

 5 tool

 6 square profile

 7 Oval profile

 8 triangle profile

 9 Cross-shaped profile

 10 Rib-shaped profile

 1 1, 12 side parts

 13, 14 mounting holes

 15 fastener

 20 base area

 21, 22 side panels

 30 threaded section

 31 collar (end stop)

 32 attachment section

 33 Cylindrical part of the transition area

34 Bent part of the transition area

35 mounting flange

 36 mounting hole

 40 spindle nut

 41, 42 fortifications

 45 Housing of the spindle gearbox

 50 cylindrical longitudinal bore

 51 stamps

 52 collet

 53, 54 slots

 55 Cylindrical recess

 56 longitudinal bore

 57 Flat extension

58, 59 faces 71, 72 side surfaces

 73, 74 tops and bottoms

 80 base area

 81, 82 thighs

 91 - 94 Peripheral ends

 95 - 98 Circular sector chamfers

 100 embossed bead

 101, 102 Formed ribs

 103 Channel-shaped depression

 300 cylindrical blank

 301, 302, sections of the cylindrical blank

303

 loading angle

 D1 - D3 diameter

 F load direction

 I area moment of inertia

 W moment of resistance

a side length

b width

d diagonal

h height

y horizontal axis

z vertical axis

Claims

claims Method for producing a threaded spindle (3) for adjustment devices in motor vehicles with a threaded section (30), at the ends of which end stops (31) for limiting the adjustment path of a drive device are arranged, and a fastening section (32) having a fastening flange (35) with a Attachment opening (36) for receiving a threaded spindle (3) with the vehicle floor connecting fastener (15) and a transition region (33, 34) between the threaded portion (30) and the mounting flange (35), wherein the threaded spindle (3) consists of a cylindrical blank (300) is formed, characterized in that the cross-sectional shape of at least a portion of the mounting portion (32) is plastically changed. A method according to claim 1, characterized in that a profile (6 - 10, 101 - 103) by cold forming to the geometry of the part of the fastening portion (32) integrally formed, in particular impressed, is. Method according to claim 1 or 2, characterized in that the cross section of the profile (6 - 10; 101 - 103) is determined as a function of the strength of the fastening section (32) to be achieved. Method according to at least one of the preceding claims, characterized in that the profile (6 - 10; 101 - 103) is embossed with a cross-section which increases the moment of resistance of the fastening section (32) in the direction of the bending and bending load of the threaded spindle (3). 5. The method according to claim 4, characterized in that the profile (6 - 10, 101 - 103) is aligned with respect to the vehicle floor such that the largest cross-sectional length with the direction of the main load of the mounting portion (32) of the threaded spindle (3). matches. 6. The method according to at least one of the preceding claims, characterized in that on a part of the transition region (33, 34) of the fastening portion (32) of the threaded spindle ribs (101, 102) are integrally formed. 7. The method according to claim 6, characterized in that the transition region (33, 34) with a with the threaded portion (30) of the threaded spindle (3) aligned part (33) and in the mounting flange (35) merging, bent part (34) is formed and in that the ribs (101, 102) to the side edges of the in the mounting flange (35) merging, bent part (34) of the transition region (33, 34) are embossed and leak into the mounting flange (35). 8. The method according to at least one of the preceding claims, characterized in that between the threaded portion (30) and the fixing portion (32) serving as an end stop of the adjustment of the adjusting device collar (31) is integrally formed. 9. The method according to claim 8, characterized in that the collar (31) by upsetting a cylindrical blank or semi-finished product (300) of the threaded spindle (3) is integrally formed. 10. The method according to claim 9, characterized in that the starting diameter of the blank or semi-finished product (300) of the threaded spindle (3) is smaller than the tip circle of the thread of the threaded portion (30) of the threaded spindle (3). A method according to claim 9 or 10, characterized in that the collar (31) before further machining processes of the threaded spindle (3) in the same tool (5) is upset. A method according to claim 9 or 10, characterized in that the collar (31) popped separately and the pressed blank (300) subsequently in further machining processes, such as forming, joining or machining for attaching the threaded portion (30) of the threaded spindle (3) Attachment section (32) and the attachment points (36) for connecting the threaded spindle (3) is machined with a mounting portion of an adjustment. 13. The method according to claim 9 or 10, characterized in that in a first processing step, the fastening portions (32) on the blank (300) of the threaded spindle (3) are formed, that in a second processing step, the collar (31) of the threaded spindle (3 ) and the pressed blank (300) in further processing steps such as forming, joining, drilling or machining for attaching the threaded portion (30) and the attachment points (36) is processed. 14. The method according to at least one of the preceding claims, characterized in that the attachment sections (32) end see the Befestigungsflan (35) arranged therein mounting holes (36). 15. The method according to claim 14, characterized in that the fastening openings (36) in further machining processes or during molding of the fastening portion (32) or the mounting flange (35) to the blank (300) are produced. 16 threaded spindle (3) for adjusting devices in motor vehicles with a threaded portion (30), at the ends of end stops (31) for limiting the adjustment of a drive means are arranged, and a fixing portion (32) having a mounting flange (35) with a mounting opening (32) 36) for receiving a threaded spindle (3) with the vehicle floor connecting fastener (15) and a transition region (33, 34) between the threaded portion (30) and the mounting flange (35), characterized in that at least a part of Fixing portion (32) has a non-rotationally symmetrical profile (6 - 10; 101 - 103). 17. Threaded spindle according to claim 16, characterized by a square profile (6). 18 threaded spindle according to claim 17, characterized in that with the threaded portion (30) of the threaded spindle (3) aligned part (33) of the transition region (33, 34) a square profile (6) with a substantially constant cross-section and a in Having the mounting flange (35), bent part (34) of the transition region (33, 34) has a square profile (6) with decreasing height up to the thickness of the mounting flange (35) and increasing width to the width of the mounting flange (35). 19 threaded spindle according to claim 17, characterized in that one of the diagonals (61) of the square profile (6) in the main loading direction of the threaded spindle (3) is aligned. 20. Threaded spindle according to claim 16, characterized by an oval profile (7). 21. Threaded spindle according to claim 20, characterized by an oval profile (7) with parallel side surfaces (71, 72) and circular sector-shaped upper and lower sides (73, 74). 22 threaded spindle according to claim 20 or 21, characterized in that the long axis (75) of the oval profile (7) in the main loading direction of the threaded spindle (3) is aligned. 23 threaded spindle according to claim 16, characterized by a triangular profile (8). 24. A threaded spindle according to claim 23, characterized in that the cross section of the triangular profile (8) consists of an isosceles triangle and that the bisecting line (83) between the equally long legs (81, 82) of the isosceles triangle in the main loading direction of the threaded spindle (3 ) is aligned. 25 threaded spindle according to claim 16, characterized by a cross-shaped profile (9). 26 threaded spindle according to claim 25, characterized in that the cross-shaped profile (9) part-circular grooves (95 - 98). 27 threaded spindle according to claim 16, characterized in that the profile of two to the side edges of the transition region (33, 34) of the fastening portion (32) integrally formed ribs (101, 102), between which a groove-shaped recess (103) is formed is. 8. Threaded spindle according to claim 27, characterized in that the ribs (101, 102) on the side edges of the in the mounting flange (35) merging, bent part (34) of the transition region (33, 34) are integrally formed and in the side edges of the mounting flange (35) expire.