WO2004004941A1 - Method and device for securing components on peripherally closed hollow profiles - Google Patents

Abstract

The invention relates to a method for fixing components (2) to peripherally closed hollow profiles (3). Walls (4,5) of the component (2) and the hollow profile (3) are connected to each other in a positive fit. In order to fix the component (2) to the hollow profile (3) in a simple manner, independent of position, the walls (4,5) to be joined are placed in an adjacent position and are locally impinged upon by external pressure such that the walls (4,5) are pressed inside (12) the hollow profile (3) and a double-walled indentation (10) is formed, whereupon the walls (4,5) are clamped against each other.

Description

 Method and device for fastening components to circumferentially closed hollow profiles

The invention relates to a method for fastening components to circumferentially closed hollow profiles according to the preamble of claim 1 and a device therefor according to the preamble of claim 15.

A generic method and a generic device is known from DE 196 18 626 C2. Holders are attached to a hollow profile in such a way that both the holder and the hollow profile are inserted into the engravings of a hydroforming tool and then the hollow profile is acted upon by means of a fluidic internal high pressure. Under this pressure, the hollow profile material flows radially outward and at the point of the holder true to the contour around walls formed on it with undercut, so that a positive connection is established between the holder and the hollow profile. The described fastening of the holder to the hollow profile is, however, only possible in the widened area between the axial sealing stamps which close the ends of the hollow profile. Furthermore, the flexibility of the method is limited to the extent that the engraving contour of the forming tool specifies the shape and location of the connection, so that different tools are required in each case with different requirements regarding the position and type of the form-fitting fastening. This results in a high level of equipment and investment.

The invention has for its object to develop a generic method or a generic device such that a secure attachment of the component on Hollow profile is made possible in a simple manner regardless of the location of the attachment.

The object is achieved by the features of claim 1 with respect to the method and by the features of claim 15 with respect to the device.

The fact that the adjacent walls of the hollow profile and the component are acted upon locally by an external pressure with the aid of a pressure medium and thereby pressed into the interior of the hollow profile with the formation of a double-walled indentation, results in a jamming of the walls, which securely fastens the component to the hollow profile guaranteed. This indentation is possible axially and radially at any point of the hollow profile and is detached from certain contour shapes of the receptacle of the hollow profile and the add-on part, so that not only the receptacle but also the entire device construction can be designed in the simplest way. With the method according to the invention, a production-safe and practicable, simple fastening possibility for hollow profiles that are not otherwise process-safe to be connected to one another, in particular hollow high-pressure formed hollow profiles with add-on parts or with other hollow profiles possibly produced in the same way, is offered.

Expedient embodiments of the invention can be found in the subclaims; otherwise, the invention is explained in more detail below with reference to several exemplary embodiments shown in the drawings; shows:

1 in a lateral longitudinal section a device according to the invention with a mandrel inserted into a hollow profile and a stamp which can be moved from the outside onto the walls of the hollow profile and component, 2 shows a cross section of the device from FIG. 1 in the pressed-in position of the stamp with an undercut recess shape of the mandrel,

3 shows, in a lateral longitudinal section, an expandable stamp of a device according to the invention,

4 shows, in a lateral longitudinal section, a device according to the invention with a stamp in the press-in phase and with a stamp from FIG. 3 spread out in the press-in position,

5 is a lateral longitudinal section of a device according to the invention with a two-part mandrel and a fluid pressure medium for indentation,

6 shows, in a lateral longitudinal section, a device according to the invention with a two-part mandrel with a squeezing effect on the wall material of the walls to be connected,

Fig. 7 in a lateral longitudinal section a device according to the invention with an elastic bellows inserted into the hollow profile.

1 shows a device 1 for fastening a component 2 to a circumferentially closed hollow profile 3. The hollow profile 3 and the component 2 are held in a receptacle, not shown here, the walls 4 and 5 of which are to be joined lying against one another. It is advantageous for the joining process and for a simplified design of the receptacle if the wall 5 of the component 2 is adapted to the wall 4 of the hollow profile 3 in accordance with the contour. The wall 5 of the flat component 2 is formed here by a flange protruding at right angles. For joining, a metallic mandrel 6 of the device 1 is now pushed into the hollow profile 3, on the circumference of which a recess 7 which is open in the sliding direction is formed. The axial opening of the recess 7 ensures easy removal of the mandrel 6 after the joining process. This recess 7 comes to lie in the place of the walls 4 and 5 to be joined. Then a plunger 8 forming the pressure medium according to the invention, which is arranged locally outside the hollow profile 3, is opposite the recess 7 directly from the outside onto the wall 5 and indirectly onto the adjacent wall 4 according to the direction of the arrow by means of a hydraulic, pneumatic, electromotive, electromagnetic, connected to the plunger 8 on the rear or move mechanical drive. In a continuing movement, the massive cylindrical punch 8 presses the walls 4 and 5 into the recess 7, which thus forms a die engraving of the dome 6 serving as a die.

Although a certain form-fitting jamming of the walls 4 and 5 is achieved, it is advantageous if the walls 4 and 5 are pressed into the recess 7 by the punch 8 in such a way that they are pressed against the recess wall 9 to effect the jamming in the manner of a To improve the press fit (Fig. 2) and to achieve a positive fit in addition to the positive connection, which holds the walls 4 and 5 more securely, ie more difficult to remove. In this case, the wall 4 of the hollow profile 3 which is closest to the recess lies against the wall 9 of the contour in accordance with the contour. The double-walled indentation 10 formed during the pressing can have essentially straight surface lines. However, the recess 7 can also be formed with undercut surfaces, in particular in the manner of a dovetail 11. As a result of the counterpressure exerted by the recess wall 9 from the interior 12 of the hollow profile 3, the walls 4 and 5 are pressed into and pressed into the recess 7 the walls 4 and 5 undercuts 13 and 14 formed. As a result, the walls 5 of the component 2 are anchored radially non-detachably in the wall 4 of the hollow profile 3. In the present exemplary embodiment, the component 2 is fastened with its wall 5 to the outside of the hollow professional wall 4. However, it is also possible within the scope of the invention to place the wall 5 of the component 2 within the hollow profile 3 and on the wall thereof 4 to be fastened on the inside. The mandrel 6 only has to be reduced in diameter. With the above variant, it is possible in a simple manner to fasten the component 2 also on the circumference of the ends of the hollow profile 3 - in extreme cases with the inclusion of the end edge of the hollow profile 3 - using other methods, in particular using the method shown in the prior art Procedure is not possible or is difficult. It is also conceivable to use a stamp design instead of the cylindrical design of the stamp 8, in which the stamp tip penetrating into the interior 12 of the hollow profile 3 is spatula-like. If the punch 8 is now pressed into the recess 7 with the walls 4 and 5, these do not completely fill the shape of the recess 7 in the axial end position of the punch 8. By rotating the plunger 8 in the axial end position by 90 °, the wall material of the walls 4 and 5 is pressed into the recess 7 in such a way that the latter is completely filled and a contour-accurate molding of the walls 4, 5 results in accordance with the shape of the recess. Then the punch 8 is turned back 90 ° and can then be easily moved out of the recess 7 and the wall indentation 10. As a result of the complete positive locking of the walls 4, 5 in the recess 7, the desired undercut is optimally formed on them, as a result of which the interlocking of the walls 4, 5 in one another and thus the hold on one another is increased.

In a further embodiment according to FIGS. 3 and 4, an advantageous variant of the invention is shown on the basis of its simple design. The receptacle forms an internal high-pressure forming tool 15, in which one or more axially spaced stamps 8 are integrated, which can be displaced in guides 16 according to the vertical double arrow. It is conceivable that the plunger 8, in its first phase, in which it presses the walls 4 and 5 into the interior 12 of the hollow profile 3, works against atmospheric pressure in the hollow profile 3, after which a high fluidic pressure is built up there (Fig. 4, I ). However, it is more economical and reduces cycle times if the hollow profile 3 is under high internal pressure while the punch 8 presses in the walls 4 and 5. The counter pressure, which was brought into contact with the punch 8 and the walls 4 and 5 for molding in the previous exemplary embodiment by contact with the recess wall 9, is here provided by the internal high pressure. Due to the forces of the internal high pressure and the plunger 8 acting on the end face 17 of the indentation 10, there is a material displacement of the hollow profile and component material that has become fluid under the internal high pressure. The end face 17 consequently thins out, which leads to a material accumulation of hollow profile and component material in the edge region 18 of the end face 17. This has the effect that undercut surfaces are formed in the indentation 10 on all sides in this area 18, so that, compared to the previous exemplary embodiment, there is an improved connection in the form of the push-through joint in any direction (axially and radially).

An increased expression of the undercut surfaces is achieved by using a stamp 8 according to FIG. 3, which can be expanded at its end 19 facing the hollow profile. This has a central axial channel 20 which tapers towards the end 19 facing the hollow profile and ends there. In the area of the taper, the punch 8 is provided, depending on the elasticity of the material of the punch 8 or its wall thickness, at least at one circumferential point with an axial slot 21 for the purpose of spreading or expanding the end 19, which cuts the channel 20 over its entire length , A pin 22 is guided displaceably in the channel 20 according to the double arrow, the pin 22 having at its lower end 23 wedge surfaces 24, by means of which it comes into contact with the channel walls when the stamp channel 20 is tapered and the slotted segments of the end 19 drifts apart. As a result, both the hollow profile and the construction Partial material of the indentation 10 in the pressed-in end position of the punch 8 in the region of the end face 17 is pressed radially apart according to the two arrows, as a result of which the undercut surfaces are enlarged (FIGS. 4, II). As a result, the positive connection between the walls 4 and 5 and thus their connection to one another is strengthened. After the desired undercut has been formed, the pin 22 is withdrawn, after which the end 19 contracts due to its elasticity into its starting position, so that the punch 8 can be moved out of the indentation 10.

In an alternative to the two exemplary embodiments described, if the receptacle is designed as an internal high-pressure forming tool 15, a mandrel 6 can also be inserted into the hollow profile 3. In this case, the mandrel 6 can advantageously form both the die for the punch 8 and the sealing axial punch of the tool 15 in a double function.

So far it has been assumed that the pressure medium according to the invention is the stamp 8. In a further exemplary embodiment, however, the pressure medium can also be a fluid pressure cushion 25, as can be seen, for example, from FIG. 5. For this purpose, a channel 27 is formed in the receptacle, which is likewise an internal high-pressure forming tool 26 here, which is connected to a pressure generator outside the receptacle and opens out on the walls 4 and 5 in the receptacle. The channel 27 is sealed in the edge region 28 of the receptacle next to its mouth opening 29 by at least one sealing ring 30. The pressure pad 25 produces almost no wear for the device 1 and has the further advantage that the pressure on the walls 4 and 5 can be set very finely and quickly and can be continuously adapted to the desired sequence of the indentation process. In the present embodiment according to FIG. 5, a mandrel 31 with little play is inserted into the hollow profile 3. In order to form undercut areas on all sides in the indentation 10 in the edge region 18 of the end face 17 the recess 32 of the mandrel 31 is trough-shaped - that is, closed all around - with a dovetail-like cross section. Through the pressure pad 25, the walls 4 and 5 are now pressed into the recess 32 until the recess wall 33 abuts, the flexibility of the pressure fluid, which counteracts the restricted movement of an in., Being used for the contour-accurate molding of the walls 4 and 5 on the recess shape rigidly shaped stamp can follow the indentation progress in all directions. The impression is thus made directly by the tensioned fluid pressure medium.

In order to remove the mandrel 31 from the forming tool 26 after the indentation 10 has been shaped and the undercut surfaces are released, the mandrel 31 is divided into two parts 34 and 35 transversely to the longitudinal extension of the mandrel 31. Each part 34 and 35 has a section of the recess 32, which is formed on the end face 36 of each part 34 and 35, so that the complete recess 32 results when the two end faces 36 abut each other. In order to ensure that the two parts 34 and 35 abut against one another during the pressing-in process, it is expedient to screw the two parts 34 and 35 together. After the indentation 10 has been formed, the screw connection is then released and the two parts 34 and 35 are pulled in the opposite direction from the hollow profile 3 or the forming tool 26. Alternatively, the parts 34 and 35 can be driven by hydraulic cylinders and held securely in the end position within the hollow profile 3. Compared to the screw connection, this saves cycle times, but is very expensive in terms of equipment. Furthermore, it is alternatively conceivable to hold the parts 34 and 35 to one another in a simple manner by means of an external, if necessary, quick-release clamping device after the end position has been reached.

To accelerate the shaping of the undercut surfaces and to improve the uniform filling of the radii of the recess 32 and thus to achieve an optimally form-fitting Sigen connection between the walls 4 and 5, the mandrel 31 has an axial fluid channel 37, from which a radial channel 38 branches off, which opens into the recess 32 at the bottom 39 thereof. The channels 37 and 38 can run alone in one of the parts 34 or 35 or - as shown in FIG. 5 - pass through the part 34 with respect to the channel 37 and run out in the part 35 and with respect to the channel 38 through a recess on both end faces 36 of the Parts 34 and 35 may be formed. By introducing a high-pressure fluid via the channels 37 and 38, the walls 4 and 5 become flowable when pressed in, so that, driven by the pressure cushion 25 in the corner regions of the recess 32, they can nestle against the wall thereof. Due to its locally limited fluid pressure, the variant described can also be used where any other deformation of the hollow profile 3 is undesirable.

A further advantageous variant is shown in the exemplary embodiment according to FIG. 6. In contrast to the variant from FIG. 5, the recess wall 33 of the parts 34 and 35 has undercut surfaces 41 when viewed in longitudinal section. Instead of the pressure pad 25 - as in the variant of FIG. 5 - a hollow or solid stamp can be used. In order to press the wall material of the walls 4, 5 into the recess 32 in such a way that it comes to conform to the contour on the undercut surfaces 41, an indentation of small depth is first produced in the two walls 4 and 5 by the pressure cushion 25 or the punch 8 , At this time, the two parts 34 and 35 are still spaced apart with their end faces 36. After the indentation has been created, the two parts 34 and 35 are now moved towards one another in the direction of the arrows, the wedge-shaped end edges 42 of the parts 34, 35 carrying the undercut surfaces 41 taking along and squeezing the wall material of the walls 4, 5. In this squeezing movement, the wall material lies against the undercut surfaces 41 in a simple manner until the two end faces 36 come into contact with one another. In order to have this process-safe, so that no wall material between the end faces 36, it must be ensured that either the indentation is small enough when the parts 34, 35 begin to approach each other, or the bottom 39 of the recess 32 must at least be so deep that the wall material of the indentation 10 only then Reason 39 comes to rest when the end faces 36 of the parts 34, 35 abut each other. The method variant described has the advantage that for the formation of the indentation 10 wall material is axially pushed in by the parts 34, 35, so that stretching which is liable to damage is prevented. Furthermore, due to the active axial action of the parts 34, 35 on the wall material, the variant represents a method of how an almost completely positive connection of two walls 4, 5 with undercut surfaces 41 can be achieved in a quick manner.

In a further advantageous exemplary embodiment according to FIG. 7, the component 2 can also be designed as a hollow profile, this being plugged together with the hollow profile 3 before being fastened. As shown in this exemplary embodiment according to FIG. 7, a hose-like elastic bellows 40 can be inserted into the hollow profile 3 lying inside, which supports the hollow profile 3 on the inside during the pressing-in process by the punch 8, a fluidic internal high pressure being exerted inside the bellows 40 which, on the one hand, expands the hollow profile 3 together with the tubular component 2 and, in cooperation with the punch 8, as already described in the exemplary embodiment in FIGS. 3 and 4, forms the undercut surfaces of the indentation 10. The bellows 40 thus forms part of a die, which additionally consists of the pressure medium itself, into which the walls 4 and 5 can be pressed. The bellows 40 ensure that the hollow profile 3 is not wetted by the pressure medium, which is favorable for easily corrodible materials. Furthermore, the bellows 40 prevent pressure fluid from escaping uncontrollably in the event of a crack forming in the indentation 10 and causing an undesirable pressure drop which would undermine a process-reliable shaping of undercut surfaces. Instead of the bellows 40, the front direction 1 contain a membrane which is attached, for example, to the axial ram.

For a further reinforcement of the connection of the walls 4 and 5, these can be coated or coated with an adhesive prior to their arrangement with one another, the adhesive ability of the adhesive being activated preferably by heat treatment after the formation of the double-walled indentation 10. As an alternative to this, the walls 4 and 5 can also be coated with a solder, which, after the indentation 10 has been formed, are soldered to one another in a furnace by heat treatment of the solder and the component 2 and the hollow profile 3.

The hollow profile 3 itself can be made from a drawn tube blank or a rolled and then longitudinally welded plate. In the same way, extruded or rolled profiles are conceivable. However, it can also be formed from two superimposed blanks by means of fluidic internal high pressure, the indentation being able to take place in a process-economical manner during or after the internal high pressure forming of the blanks. The hollow profile 3 can have a circular cross-section according to the tube blank shape or also have other cross-sectional shapes that are caused by flattening, folding and squeezing or the like. can be achieved.

In addition, the indentation 10 can also run around the component 2 and the hollow profile 3 in the manner of an annular groove. The pressure pad 25 and a segmented ring stamp are conceivable as pressure medium, which comprises component 2 as well as hollow profile 3.

An additional advantage of the exemplary embodiments according to FIGS. 4 and 7 should also be mentioned at this point. The internal high pressure ensures that when the walls 4, 5 are pressed in by means of the plunger 8 or the pressure pad 25 in the edge region adjacent to the indentation 10, there are no sinking deformations with large bending forces due to the all-round support of the internal high pressure 3. dien form that conflict with the dimensional accuracy of the outer contour of the hollow profile 3. Thus, the contour profile remains unaffected when pressed in, which, among other things, meets the visual requirements for the assembly of the hollow profile 3 on the component 2.

Claims

DaimlerChrysler AG patent claims 1. A method for fastening components to circumferentially closed hollow profiles, the walls of the component and the hollow profile being connected to one another in a form-fitting manner, characterized in that the walls (4, 5) to be joined lie against one another and are acted upon locally by an external pressure, so that there the walls (4, 5) are pressed into the interior (12) of the hollow profile (3) to form a double-walled indentation (10), the walls (4, 5) being clamped together. 2. The method of claim 1, d a d u r c h g e k e n n z e i c h n e t that the indentation takes place mechanically by means of a stamp (8). 3. The method according to claim 1, which also means that the indentation is carried out directly by a tensioned fluidic pressure medium. 4. The method according to any one of claims 1 to 3, that the component (2) with its wall (5) is fastened to the inside of the hollow profile wall (4) with its wall (5). 5. The method according to any one of claims 1 to 3, characterized in that the component (2) with its wall (5) is attached to the outside of the hollow professional wall (4). 6. The method according to any one of claims 1 to 5, so that the component (2) is designed as a hollow profile and is plugged together with the hollow profile (3) before fastening. 7. The method according to any one of claims 1 to 5, so that the component (2) is fastened to the hollow profile (3) with a flange. 8. The method according to any one of claims 1 to 7, characterized in that the walls (4,5) in a recess formed on the circumference (7,32) of a in the hollow profile (3) pushed mandrel (6,31) until the system wall (4, 5) of the component (2) or the hollow profile (3) closest to the recess is pressed against the wall of the recess (7, 32) according to the contour. 9. The method according to any one of claims 1 to 8, characterized in that when the walls (4, 5) are pressed in by an undercut (13) exerted by a back pressure exerted on the walls (4, 5) from the inside (12) of the hollow profile (3). 14) are formed. 10. The method according to claim 9, so that the counterpressure is generated by a high fluid pressure in the hollow profile (3). 11. The method according to any one of claims 9 or 10, characterized in that the undercuts (13, 14) are formed with the aid of a radial expansion of an expandable end (19) facing the hollow profile of a stamp (8) located in the indentation position. 12. The method according to any one of claims 1 to 11, characterized in that before arranging the walls (4,5) to be fastened together of the component (2) and the hollow profile (3) to one another, at least one of the walls (4,5) with an adhesive is provided and that after the formation of the double-walled indentation (10) the adhesiveness of the adhesive is preferably activated by heat treatment. 13. The method according to any one of claims 1 to 11, characterized in that before arranging the walls (4,5) to be fastened together of the component (2) and the hollow profile (3) to one another, at least one of the walls (4,5) is coated with solder and that after the formation of the double-walled indentation (10) the component (2) and the hollow profile (3) are soldered to one another by heat treatment of the solder. 14. The method according to any one of claims 1 to 13, so that the hollow profile (3) is formed from two superimposed blanks by means of fluidic high pressure and that the indentation takes place during or after the high pressure forming of the blanks. 15. Device for fastening components to circumferentially closed hollow profiles, with a receptacle in which the hollow profile and the component are held in such a way that walls of the hollow profile and the component lie against one another, and with a pressure medium, under the action of which the walls form-fit can be connected, characterized in that the pressure medium is arranged locally outside the hollow profile (3) and is designed to be movable in such a way that the adjoining walls (4, 5) to be joined into the interior (12) of the hollow profile (3) to form a double-walled indentation (10) can be pressed in and clamped together. 16. The apparatus of claim 15, d a d u r c h g e k e n n e e e c h n e t that the pressure medium is a fluid pressure cushion (25). 17. The apparatus according to claim 15, so that the pressure medium is a stamp (8) provided on the back with a drive. 18. Device according to one of claims 15 to 17, so that the receptacle is a high-pressure forming tool (15, 26). 19. Device according to one of claims 15 to 18, characterized in that the device (1) includes a mandrel (6) which can be pushed into the hollow profile (3) and forms a die for the pressure medium, with a circumference in the sliding direction Open recess (7) is formed, which forms a die engraving into which the walls (4, 5) can be pressed for joining by means of the pressure medium. 20. The apparatus according to claim 19, so that the mandrel (6) is an axial punch that seals an internal high-pressure forming tool (15, 26). 21. Device according to one of claims 19 or 20, d a d u r c h g e k e n n z e i c h n e t that the recess (7, 32) has undercut surfaces. 22. The apparatus according to claim 21, characterized in that the undercut surfaces are designed in the manner of a dovetail (11). 23. Device according to one of claims 19 or 20, so that the mandrel (6, 31) has an axial fluid channel (37), from which a radial channel (38) branches, which opens into the recess (7, 32). 24. Device according to one of claims 17 to 23, so that the stamp (8) can be expanded at its end facing the hollow profile (19). 25. Device according to one of claims 15 to 24, characterized in that the device (1) has a membrane or a hose-like bellows (40) which can be inserted into the hollow profile (3) and is supported on the inside during the pressing-in process, wherein the membrane or the bellows (40) forms part of a die into which the walls (4, 5) can be pressed.