Method for forming a tubular structural component for motor vehicle seats

Abstract

Method for forming an end of a tubular structural component for motor vehicle seats, which is upset to form a stop for a connecting part of the motor vehicle seat and inserted into a bore of the connecting part, characterized by a multi-stage forming process in which, in a first process step, the end (12) of the tubular structural component (1) is partially pre-formed circumferentially and, in a second process step, is fully expanded.

Description

[0001] The invention relates to a method for forming an end of a tubular structural component for motor vehicle seats according to the preamble of claim 1 and to a device for carrying out the method according to claim 9.

[0002] From DE 10 2013 209 948 A1, a method for forming a tubular structural component for motor vehicle seats is known, which is upset to form bead- or tulip-shaped stops for flanges or frame parts of the motor vehicle seat and inserted into bores of the flanges or frame parts. The area of ​​the tubular structural component to be raised is heated before forming.

[0003] Tubular structural components with bead- or tulip-shaped stops are used, for example, in height adjustment devices for motor vehicle seats. These devices each have two flanges, pivotable relative to the vehicle floor, arranged on either side of the front and rear ends of the vehicle seat. Each flange is connected to the other and to a seat base via a swivel tube. The flanges have a bore through which the ends of the swivel tube are inserted. To axially secure the connection between the swivel tube and the flanges, in a first embodiment the swivel tube has upturned beads or tulips located away from its end faces. These beads or tulips bear against both sides of the flanges, while the connecting sections of the transverse tube located between the beads or tulips are positioned in the bores of the flanges.

[0004] To form the ridges or tulips, the rotary tube is deformed radially outwards, creating two adjacent folds projecting perpendicularly from the longitudinal axis of the rotary tube, the radial ends of which are bent at a 360° angle. These ridges or tulips, formed at an axial distance on both sides of the connecting section, define the connecting section of the rotary tube and, in the assembled state, lie tightly against the side surfaces of the flanges of the height adjustment mechanism or the frame components of the vehicle seat.

[0005] In a second embodiment, the connecting sections for receiving the connecting part designed as a flange, frame part or clamping ring are arranged between the beads or tulips formed at the end faces of the rotary tube and the upturned end faces of the rotary tube, which serve, among other things, to axially secure the connecting part in the event of a crash.

[0006] To form the end faces of the tubular structural component, a conical or frustoconical pressing tool is used, the larger diameter of which is a predetermined amount larger than the outer diameter of the tubular structural component. To widen the outer diameter of the end faces of the tubular structural component, the conical or frustoconical pressing tool, inserted into the tube ends, is pressed axially into the tubular structural component with a predefined force using a hydraulic or pneumatic pressing device. This force must be at least sufficient to cause the material of the tubular structural component to yield beyond its tensile strength.

[0007] The cone angle of the pressing tool depends on the emerging outer diameter of the end face of the tubular structural component, whereby the cone angle and the material of the tubular structural component determine the force required for upsetting and thus the stress on both the tubular structural component and the hydraulic or pneumatic pressing device and the pressing tool.

[0008] Because of the high forming forces required for the forming process, which must be introduced into the tubular structural component, the press device and the press tool must be dimensioned accordingly, and there is a risk of pre-damage to the tubular structural component, which destroys the fit between the connecting section and the connecting part due to the high force, resulting in jamming or unwanted play between the connecting section and the bore of the connecting part.

[0009] The object of the present invention is to provide a method of the type mentioned at the outset, by which the end face of a tubular structural component is expanded or compressed to a predetermined outer diameter with reduced forming force.

[0010] This problem is solved according to the invention by the features of claim 1.

[0011] The solution according to the invention enables the expansion or upsetting of the end face of a tubular structural component to a predetermined outer diameter with reduced forming force, so that both the pressing device and the pressing tool as well as the tubular structural component are subjected to significantly less stress when expanding the end face of the tubular structural component, thereby ensuring that such formed end faces of the tubular structural component are not destroyed or impaired in their function even under high or extremely high loads and especially in the event of a crash.

[0012] Partial circumferential pre-embossing can be performed either at specific points around the circumference, i.e., with a minimal circular sector or arc, or section by section, i.e., with a defined arc length. The optimal size and number of partial circumferential pre-embossings in the first process step depend on the desired outer diameter of the expansion, the wall thickness of the tubular structural component, and its material.A greater number and / or arc length of the circumferential partial pre-embossings necessitates a greater axially directed forming force in the first process step, but reduces the required axial forming force for full expansion in the second process step, and vice versa. An optimum with minimal forming force and thus minimal stress on the press, the press tool, and the tubular structural component is achieved when the pre-embossing force to be applied axially in the first process step is at least approximately equal to the forming force to be applied axially in the second process step.

[0013] To avoid pre-embossing forces occurring during partial pre-embossing in the first process step, which would lead to a displacement of the connecting section relative to the central longitudinal axis of the tubular structural component and thus to an inclination of the connecting part, a further feature of the inventive method is that the end of the tubular structural component is pre-embossed uniformly over its circumference.

[0014] Preferably, in the first process step, the end of the tubular structural component is pre-marked circumferentially at at least three points or sections arranged at equal angular distances from each other.

[0015] A material-friendly partial pre-embossing and full widening of the end of the tubular structural component is achieved by continuously widening the end of the tubular structural component in the axial direction at the locations of the partial pre-embossing in the first process step and by continuously widening it fully towards the end of the tubular structural component in the axial direction in the second process step.

[0016] A device for carrying out the method according to the invention is characterized by a first pressing tool with a base body which can be connected to a hydraulic or pneumatic pressing device, and a pressing punch which consists of several pre-embossing elements arranged distributed around the circumference of the pressing punch, wherein the pre-embossing elements consist of radially oriented pre-embossing bars arranged at equal intervals around the circumference, the radial outer edges or surfaces of which have a decreasing distance to the central longitudinal axis of the pressing punch in the axial direction starting from the base plate to the opposite end of the first pressing tool.

[0017] For targeted partial pre-embossing to a predetermined outer diameter that is smaller than or equal to the outer diameter of the full-circumference expansion, the pre-embossing sections form segments of a truncated cone.

[0018] Gentle pre-embossing that avoids material tears is achieved by rounding or forming circular arcs on the outer edges of the pre-embossing elements or pre-embossing bars.

[0019] An optimum in terms of force between the partial pre-embossing in the first process step and the full expansion in the second process step is achieved by at least three pre-embossing bars arranged circumferentially offset by 120° to each other and a maximum of eight pre-embossing bars arranged circumferentially offset by 45° to each other.

[0020] The device for carrying out the method according to the invention is completed by a second pressing tool with a cylindrical base body connectable to a hydraulic or pneumatic pressing device and a pressing ram with a cylindrical connecting section adjacent to the base body, a frustoconical forming section adjoining the connecting section, the larger diameter of which connects to the connecting section, a cylindrical guide section adjoining the smaller diameter of the forming section and a frustoconical insertion section, the larger diameter of which connects to the guide section.

[0021] The method according to the invention will be explained in more detail with reference to an embodiment shown in the drawing. The drawing shows:

[0022] Fig. 1 and Fig. 2 an exploded view and an isometric view of a tubular structural component inserted into a bore of a connecting part designed as a seat side part with a bearing bushing and retaining ring inserted therein, the end-side connecting surface of which is axially limited by a tuft or bead;

[0023] Fig. 3 an isometric view of a press die for the partial pre-forming of the end face of the tubular structural component for axial securing of the connection of the structural component with a connecting part;

[0024] Fig. 4 to Fig. 6 an isometric view, side view and top view of the pre-embossing guides of the press die for the partial widening of the end face of the tubular structural component;

[0025] Fig. 7 an isometric view of the tubular structural component inserted into the bore of the seat side part after partial pre-embossing of the end face of the tubular structural component;

[0026] Fig. 8 a longitudinal section through the pre-embossed end face of the tubular structural component before its complete expansion by a press punch with a frustoconical forming section and

[0027] Fig. 9 and Fig. 10 an isometric view of the fully expanded or compressed end of the tubular structural component and a longitudinal section through the tubular structural component connected to the seat side part with a fully expanded end face for axial securing of the connection.

[0028] The Fig. 1 and Fig. Figure 2 shows, in an exploded view and an isometric view, a bearing point of a seat height adjustment for connecting a tubular structural component designed as a transverse tube. 1 , the end of which is a connecting or storage surface 10 to accommodate a bearing bushing 5 features on which the bore 20 a connecting part in the form of a seat side panel 2 is attached. The storage area 10 is axially through a line from the end of the transverse tube 1 spaced tuft or bead 11 limited, to which one side of the seat side panel is attached. 2 Attaches. For axial securing of the connection of the seat side panel. 2 with the cross tube 1 A bearing bushing will be radially attached to it 5 attaching retaining ring 6 to the storage area 10attached, which blocks axial displacement against the insertion direction and thus the connection of the cross tube 1 with the seat side panel 2 to absorb operating forces that occur during the operation of the height adjustment device, securing it axially.

[0029] Since the crash forces occurring in a crash can significantly exceed the operating forces, there is a risk of the connection of the seat side panel coming loose. 2 with the cross tube 1 And since there is a risk of injury to the person sitting in the vehicle seat, additional axial securing of the connection of the seat side panel is carried out. 2 with the cross tube 1 the front end 100 of the cross tube 1 with a widening 17 provided so that both sides of the storage area 10 axial stops due to the tuft or bead 11 and the expansion 17according to the Fig. 9 and Fig. 10 are provided, which are also effective in the event of a crash.

[0030] Instead of a seat side panel, a flange or other frame component of a motor vehicle seat can also be used as a connecting element. The widening of the end face of the tubular structural component is also possible. 1 for axial securing of a connecting part 2 also intended for normal operation.

[0031] To form the bulge or tulip 11 will the cross tube 1 radially deformed outwards, so that two adjacent, perpendicular to the longitudinal extent of the transverse tube 1 Protruding folds form, the radial end of which is bent at an angle of 360°. The end widening or upsetting 16 is produced by a two-stage forming process described below and forms a tuft or bead. 11an axial stop to which the parts attached to the bore of the seat side panel can be attached 2 adjacent sides of the seat side panel 2 invest.

[0032] While the tufting is carried out in the manner described above, the widening or upsetting of the end of the tubular structural component is carried out. 1 carried out in two successive process steps to reduce the axial deformation force required for expansion or upsetting and thus the load on the pressing device, the pressing tool and in particular the tubular structural component 1 to minimize.

[0033] The first step in the process involves a partial pre-shaping of the end. 12 of the tubular structural component 1 , where only specific or small sections of the end 12 the cylindrical surface of the tubular structural component 1The ends are pre-marked. These pre-marks are evenly distributed around the circumference of the end. 12 the cylindrical surface of the tubular structural component 1 distributed and therefore require a lower axial pre-forming force than a full widening of the end. 12 the cylindrical surface of the tubular structural component 1 in one process step.

[0034] Fig. Figure 3 shows an isometric representation of a first pressing tool. 3 to carry out the first process step, i.e., to partially pre-form the end face of the tubular structural component 1 This first pressing tool 3 features a cylindrical base body that can be connected to a hydraulic or pneumatic pressing device 30 and a press stamp 31 on, which consists of a cylindrical base 32and four pre-embossing bars arranged circumferentially offset from each other by 90° 33 consists of whose rounded radial outer surfaces 34 according to the isometric representation in Fig. 4, the side view according to Fig. 5 and the top view according to Fig. 6 in the axial direction starting from the cylindrical base 32 to the basic body 30 opposite end of the first pressing tool 3 a decreasing distance to the central longitudinal axis of the press ram 31 exhibiting, i.e., whose imaginary lateral surface is frustoconical with a flattened end 35 is trained.

[0035] In contrast to the one in the Fig. 3 to Fig. 6 illustrated press dies 31 with four pre-embossing points arranged at 90° intervals from each other 33 can the press stamp 31also from three or more than four evenly spaced around the circumference of the press die 31 distributed pre-embossing marks 33 consist of a minimum of three pre-embossing elements, each offset by 120° from the others. 33 and an even distribution of the pre-embossing steps 33 about the circumference of the press die 31 prevents pre-forming forces from occurring during partial pre-forming in the first process step, which could lead to a displacement of the connecting section. 10 opposite the central longitudinal axis of the tubular structural component 1 and thus to an inclination of the connecting part 2 lead.

[0036] Partial circumferential pre-embossing can be performed either circumferentially at specific points, i.e., with a minimal arc length, or circumferentially in sections, i.e., with a defined arc length. The optimal size and number of partial pre-embossings depend primarily on the desired outer diameter of the pre-embossing, the wall thickness of the tubular structural component, and its material. A greater number and / or arc length of the partial circumferential pre-embossings necessitates a greater axially directed pre-embossing force in the first process step, but reduces the required axial forming force for full expansion in the second process step, and vice versa. Therefore, an optimum with minimal axial pressing force, and thus minimal stress on the press, the press tool, and the tubular structural component, is achieved when the pre-embossing force and the forming force are approximately equal.

[0037] After the tubular structural component has been tufted open 1 for the formation of the end face of the tubular structural component 1 distant tulip or bead 11 will the connecting part 2 with the one in the bore 20 inserted bearing bushing 5 to the storage area 10 attached and in this embodiment the retaining ring 6 to the storage area 10 The end of the tubular structural component is then attached. 1 for axial (crash) securing of the connecting part 2 in two process steps with a partial pre-shaping of the end 12 of the tubular structural component 1 in the first process step and a subsequent full widening of the tubular structural component 1 In the second process step, it is deformed or compressed.

[0038] For pre-forming the end face of the tubular structural component 1 will be the first pressing tool 3 into the front opening of the tubular structural component 1 inserted and, by means of a hydraulic or pneumatic pressing device, in an axial direction to the opposite end of the tubular structural component 1 moved, so that the pre-embossing marks 33 in contact with the end wall of the tubular structural component 1 step and, with further advancement of the first pressing tool, the end wall of the tubular structural component 1 Partially pre-emboss at these points.

[0039] Fig. Figure 7 shows the end face in an isometric view. 12 of the tubular structural component 1 after completion of the first process step with the partial pre-embossing of the end face of the tubular structural component 1at four pre-pressing stations 13 , 14 , 15 , 16 , which are formed by the four pre-embossing bars offset by 90° to each other 33 of the first pressing tool 3 were manufactured.

[0040] After the partial pre-shaping of the tubular structural component 1 In the first process step, the tubular structural component is fully expanded. 1 in the second process step using the second pressing tool 4 , which corresponds to the longitudinal section according to Fig. 8 from a cylindrical base body connectable to a hydraulic or pneumatic pressing device 40 and a press stamp 41 until 44 with one attached to the base body 40 adjacent cylindrical connecting section 41 , one connected to the connecting section 41 subsequent, frustoconical forming section 42, which, with its larger diameter, connects to the connecting section 41 connecting to the smaller diameter of the forming section 42 adjacent cylindrical guide section 43 and a frustoconical inlet section 44 , whose larger diameter is attached to the guide section 43 connects, exists.

[0041] The second pressing tool 4 is applied by means of a hydraulic or pneumatic pressing device in the direction of arrow K according to Fig. 8 into the one with the partial pre-embossing points 13 , 14 , 15 , 16 provided end 12 of the tubular structural component 1 pressed in, whereby the frustoconical wall of the forming section 42 of the second pressing tool 4 to the inner wall of the end 12 of the tubular structural component 1 lays up and the end 12according to the isometric representation of the Fig. 9 and the longitudinal section through the connection of the transverse tube 1 formed tubular structural component with the seat side panel 2 trained connecting part according to Fig. 10 to a predetermined outer diameter corresponding to the insertion depth of the second pressing tool 4 to form a full expansion 17 deformed. Reference symbol list 1 tubular structural component (cross tube) 2 Connecting part (seat side part) 3 first pressing tool 4 second pressing tool 10 Connecting or storage area 11. Bulging or bead 12. End face of the tubular structural component 13–16 pre-embossing points (partial widenings) 17 Expansion 20 bore 30 cylindrical base bodies 31 press dies 32 cylindrical base 33 Pre-embossing steps 34 rounded radial outer surfaces 35 flattened end 40 cylindrical base bodies 41 cylindrical connecting section 42 frustoconical forming section 43 cylindrical guide section 44 Fructed-cone-shaped introduction section K Axial force QUOTES INCLUDED IN THE DESCRIPTION

[0042] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0043] DE 102013209948 A1

[0002]

Claims

[1] Method for forming an end of a tubular structural component for motor vehicle seats, which is upset to form a stop for a connecting part of the motor vehicle seat and inserted into a bore of the connecting part, characterized by a multi-stage forming process in which, in a first process step, the end ( 12 ) of the tubular structural component ( 1 ) is partially pre-molded on the circumference and fully widened in a second process step. [2] Method according to claim 1, characterized by that the end ( 12 ) of the tubular structural component ( 1 ) is pre-marked at specific points along the circumference in the first process step. [3] Method according to claim 1, characterized by that the end ( 12 ) of the tubular structural component ( 1 ) is pre-molded section by section in the first process step. [4] Method according to at least one of the preceding claims, characterized by that the number and / or arc length of the partial widenings ( 13 – 16 ) is determined in such a way that the axial pre-forming force to be applied in the first process step is used for the partial pre-forming of the end ( 12 ) of the tubular structural component ( 1 ) at least approximately equal to that in the second procedural step for full expansion ( 17 ) of the end ( 12 ) of the tubular structural component ( 1 ) required axial forming force. [5] Method according to at least one of the preceding claims, characterized by that the end ( 12 ) of the tubular structural component ( 1 ) is partially pre-embossed evenly distributed across its circumference in the first process step. [6] Method according to claim 5, characterized by that the end ( 12 ) of the tubular structural component ( 1) in the first process step, a pre-marking is made on the circumference at at least three points or sections arranged at equal angular distances from each other. [7] Method according to at least one of the preceding claims, characterized by that the end ( 12 ) of the tubular structural component ( 1 ) at the locations of the partial pre-embossings ( 13 – 16 ) to the front ( 12 ) of the tubular structural component ( 1 ) is continuously and increasingly pre-shaped in the axial direction. [8] Method according to at least one of the preceding claims, characterized by that the end ( 12 ) of the tubular structural component ( 1 ) in the second process step, it is continuously and increasingly widened in the axial direction. [9] Device for carrying out the method according to at least one of the preceding claims, characterized by a first pressing tool ( 3) with a basic body ( 30 ), which can be connected to a hydraulic or pneumatic pressing device, and a pressing ram ( 31 ), which consists of several, around the circumference of the press die ( 31 ) distributed pre-forming elements ( 33 ) consists. [10] Device according to claim 9, characterized by that the pre-embossing elements consist of radially oriented pre-embossing bars arranged at equal intervals around the circumference ( 33 ) exist, whose radial outer edges or surfaces ( 34 ) in axial direction starting from the base body ( 30 ) to the opposite end of the first tool ( 3 ) a decreasing distance to the central longitudinal axis of the press ram ( 31 exhibit. [11] Device according to claim 10, characterized by that the pre-embossing points ( 33 ) Form sections of a truncated cone. [12] Device according to claim 10 or 11, characterized bythat the outer edges or outer surfaces ( 34 ) the pre-embossing elements or pre-embossing steps ( 33 ) are rounded or arc-shaped. [13] Device according to one of the preceding claims 10 to 12, characterized by at least three pre-embossing bars arranged circumferentially offset from each other by 120° ( 33 ). [14] Device according to one of the preceding claims 10 to 13, characterized by a maximum of eight pre-embossing bars arranged circumferentially offset from each other by 45° ( 33 ). [15] Device according to at least one of the preceding claims 9 to 14, characterized by a second pressing tool ( 4 ) with a cylindrical base body that can be connected to a hydraulic or pneumatic pressing device ( 40 ) and a press punch with a base body attached ( 40 ) adjacent cylindrical connecting section ( 41), one connected to the connecting section ( 41 ) subsequent, frustoconical forming section ( 42 ), which, with its larger diameter, connects to the connecting section ( 41 ) connects to the smaller diameter of the forming section ( 42 ) adjacent cylindrical guide section ( 43 ) and a frustoconical inlet section ( 44 ), whose larger diameter is attached to the guide section ( 43 ) connects.