DE10250118A1 - Method for attaching an insert to a component made of a lightweight material - Google Patents

Abstract

A method for fastening an insert (6) that can be used as a mounting element to a component (1) made of a lightweight material, in particular a metallic-cellular material, is described. For this purpose, the component (1) is provided with a recess (2) into which a body (5) made of thermoplastic material is introduced. The insert (6) is fastened to a sonotrode (9) for insertion into the recess (2), which is used for plasticizing the thermoplastic material and thereby for a firm material and / or positive connection of the insert (6) to the component (1). is used in the region of the recess (2) (Fig. 5).

Description

The invention relates to a method specified in the preamble of claim 1 Genus.

Components made of lightweight materials, especially metal foams and others (Metallic) cellular materials are increasingly used in vehicle construction to sufficient strength and rigidity to reduce the component mass. But you find also used in wide areas of mechanical engineering and are characterized by Dissolution of the compact and massive structure in an open or closed pore cellular structure. For the industrial (large) use of such materials or with these manufactured composite materials, it is necessary, preferably with ans Metal-made mounting elements such. B. screws, bolts, pins or the like Mistake. Suitable joining methods are required for this, since the assembly elements are not can easily be permanently attached to the components.

Adhesive bonding, screwing, soldering and special welding processes proven. However, this does not apply without restriction.

Problems arise with the direct welding of metal foams, which are on the foam side to the very small and above all uneven thickness of the welded Areas. The relatively high welding temperature implies Residual stress in the heat affected zone and usually leads to warpage.

When soldering foam materials, due to the penetration of soldering flux in the porous foam structure corrosion problems as well as influencing the Properties of the cellular material occur in the contamination area. Furthermore, the The strength of soldered connections is often considerably lower than the technical yield point of the foam material with the same density.

The only non-positive joining process "screws" is due to insufficient Strength of the foam structure can hardly be used.

An areal or volume-like and materially joining process would be ideal. This Adhesion meets the requirements as a joining technique. Leave almost all material groups join together without impermissibility of the material properties of the parts to be joined to be changed. Gluing is one of the low-heat joining processes, in which none local weakening of the joining zone but a flat material connection of the Joined parts are made. Their strength is usually higher than that of the cellular one Material. Furthermore, the "gluing" joining method can be used in particular in the case of mixed construction, ie H. when using different metallic and / or non-metallic materials have multifunctional properties and additional tasks such as electrochemical Take over insulation and sealing function. Disadvantageous in terms of The process speed is the curing time, which often lasts several hours at room temperature suitable, in particular thermosetting reactive adhesives. A shortening of the Curing times would be possible by increasing the curing temperature, but requires additional equipment and financial effort.

In the case of installation elements in the form of inserts with which Screws, pins, nuts or the like could be firmly connected, allow metallic cellular materials (e.g. metal foams) the foaming or foaming of these inserts directly in the manufacturing process. However, only compact materials are suitable for this, which has a higher melting point than the prevailing process temperatures at Have foams. The use of such inserts made of compact material requires because of the considerable thermal load a larger volume and contradicts thus the lightweight design concept behind the use of cellular materials. On the other hand, the position of the fastening element is unambiguous due to the foaming set, and any tolerance overlaps may no longer be possible be balanced.

In addition, it is used to establish a firm connection between a component from a cellular material and a component made of a compact material known (DE 199 17 132 A1), to put the two components together and then by ultrasonic welding connect with each other. To make solid and permanent connections however, relatively large contact areas are required, which are not always desirable are and are not always available.

To connect plate-shaped components, it would also be possible to use a plate to be provided with a recess, insert a sleeve-shaped insert into it and then connect its bottom to the other plate by ultrasonic welding (DE 196 10 636 C2). However, such a type of attachment requires that at least the insert consists of a material that can be welded by ultrasonic energy, which consists of Stability reasons is not always desirable. It also says Procedure with the bottom of the insert only a comparatively small contact area available for the non-positive connection to be established.

Another known method (U.S. Patent 4,817,264) uses flanges Provided, rivet-like inserts used in through holes in the components used and on the protruding from the flanges, protruding from the holes Ends are plasticized by ultrasonic energy and deformed into rivet heads like this 1 is common in ultrasonic welding. The addition is made here exclusively by positive locking and requires a recess that completely penetrates the component.

If a recess in the form of a blind hole is desired instead, then you must first once a receiving body made of thermoplastic material is fastened in the recess be what in a special operation by forming an adhesive and Snap connection tracked. Then the actual use by ultrasonic energy in the Attachment body attached, so that it is a comparatively complex and only with suitable joining processes, which are fastened to the component, can be carried out.

Finally, a method of the type described in the introduction is known (DE 695 03 284 T2), in which a plate-shaped, made of foam or honeycomb material Component on opposite broad sides with cover layers or thermoplastic Material occupied and with a recess intended to accommodate an insert is provided. The insert is made of thermoplastic material and points to it axial ends on so-called sacrificial edges, which are plasticized by ultrasonic vibrations and with the edges of the two cover layers bordering on the recess to be merged. This procedure is therefore only applicable when both the stakes as well as the cover layers made of a thermoplastic material or the Inserts in a complex process step with thermoplastic sacrificial edges be provided.

Against this background, the invention is based on the technical problem that Develop the method of the type described in the introduction so that it also becomes Connection of metallic inserts on components made of metallic-cellular materials or composite materials made from it, is easy to use permanently good fastening of the inserts in the components and, in principle, neither Cover layers still require continuous recesses for the inserts.

The characteristic features of claim 1 serve to solve this problem.

The invention has the advantage that the additional introduction of a Body made of thermoplastic material through an insert made of metal Ultrasonic energy can be connected to a component that is also made of metal can. The connection does not have to be flat by contacting the insert with the Component take place on the broad sides provided, but can rather in substantial volume in the recess itself with the help of an intermediate layer thermoplastic material can be made. If a component is made from a (metallic) cellular material used, there is the further advantage that the Thermoplastic material penetrate deep into the pores of the material and thereby one can form-fit connection with this. The same applies on the side of the Use, if this with its in the recess protruding outer surface with the recording suitable recesses of the thermoplastic material is provided. The Joining method according to the invention also requires neither a penetrating component Recess still any top layers and is largely independent of that for that Component and the intended materials feasible.

Further advantageous features of the invention emerge from the subclaims.

The invention will be described in connection with the accompanying drawings Embodiments explained in more detail. Show it:

Fig. 1 shows a schematic section through an insert with a Being Trapped component in a first stage of the method;

. Figs. 2 to 4 of Figure 1 are corresponding views of further stages of the method according to the invention;

FIG. 5 shows a view corresponding to FIG. 2 on an enlarged scale; and

FIGS. 6 and 7 of Fig. 1 corresponding views with the use of alternative embodiments of the inventive method.

In the embodiment of FIGS. 1 to 4, a component 1 with a z. B. cylindrical recess 2 is provided, which is incorporated from a broad side 3 and is designed in the manner of a blind bore. The recess 2 has a central axis 4 , which in the exemplary embodiment runs essentially perpendicular to the broad side 3 . A body 5 made of a thermoplastic material is arranged in the recess 2 , which in the exemplary embodiment is designed as a sleeve-shaped or hollow-cylindrical hollow body and has an axial height which is expediently equal to the depth of the recess 2 . In the inserted state of Fig. 1, the body 5 therefore closes flush with the broad side 3.

An insert 6 is provided to be inserted into the recess 2 and to be firmly connected to the component 1 . The insert 6 has at its upper end, as shown in particular in FIG. 4, an axial bore 8 provided with an internal thread 7 . After the insert 6 has been fastened to the component 1, a fastening screw or the like can be screwed into this bore 8 , as a result of which the insert 6 forms a mounting element by means of which any other components per se can be firmly connected to the component 1 .

As shown in FIGS. 1 to 3, the bore 8 also serves to accommodate the free end of a sonotrode 9 when carrying out the joining method according to the invention, which is provided with an external thread that fits into the internal thread 7 and can be screwed firmly into the bore 8 .

The attachment of the insert 6 in the recess 2 is carried out according to the invention, for. B. by first introducing the body 5 made of thermoplastic material into the recess 2 and then the insert 9 previously screwed to the sonotrode 9 is approximated coaxially to the central axis 4 in the direction of the arrow of the recess 2 ( FIG. 1). As soon as the lower end of the insert 6 has reached the body 5 ( FIG. 2), the sonotrode 9 is activated or set in mechanical ultrasonic vibrations until the thermoplastic material of the body 5 has been largely or completely plasticized and is therefore close to the the circumferential wall of the component 1 enclosing the recess 2 and the outer jacket surface of the insert 6 lying opposite it nestles. Of course, the sonotrode 9 can also be activated shortly before or after the insert 6 has been brought into contact with the body 5 , as required.

After being placed on the body 5, the insert 6 is advanced continuously or stepwise with a force F in the direction of the arrow until it lies preferably on the bottom of the recess 2 ( FIG. 3) and the plasticized thermoplastic material 10 of the body 5 ( FIG. 3 and 4) completely in the space between the peripheral wall of the recess 2 and the outer surface of the insert 6 and is uniformly distributed in this. The sonotrode 9 is then unscrewed from the bore 8 and removed ( FIG. 4). The cooled thermoplastic material 10 then creates an intimate and firm connection between the insert 6 and the component 1 . The entire joining process, including the cooling of the thermoplastic material, only takes a few seconds.

To insert the insert 6 into the recess 2 , the sonotrode 9 is expediently attached to a converter, not shown, which, for. B. designed as a piezoelectric vibration generator and in turn is coupled to a motor, hydraulic or pneumatic operated feed unit. Suitable devices are e.g. B. generally known in devices for ultrasonic welding.

To carry out the joining method described, it is expedient if the body 5 has an outer cross section K _a ( FIG. 5) which is slightly smaller than the inner cross section A _{i of} the recess 2 and is therefore easily inserted into the recess 2 with a small gap dimension can be. In contrast, the z. B. cylindrical insert 6 have an outer cross section E _a , which is slightly larger than the inner cross section K _{i of} the body 5 . It is thereby achieved that the cavity formed between the insert 6 and the peripheral wall of the recess 2 has a somewhat smaller volume than the body 5 and the thermoplastic material is therefore displaced radially to the central axis 4 when inserting the insert 6 and during melting. Excess thermoplastic material can therefore enter, in particular, open pores and other cavities formed in the circumferential wall of the recess 2 , such as are present in particular when using metallic-cellular materials and other lightweight materials, and in this way a positive connection parallel to the central axis 4 enter with the peripheral wall of the recess 2 .

The insert 6 , which preferably consists of a hard, solid metal, is provided in a particularly preferred exemplary embodiment of the invention on its outer, originally cylindrical outer surface with at least one recess 11 ( FIG. 5), which, for. B. by a circumferential, incorporated into the lateral surface notch, groove, groove or other. Recess is formed and adjacent ribs 12 with the dimension E _{a can} stand. A plurality of such depressions 11 are preferably provided. As a result, the thermoplastic material 10 , as shown in FIGS. 3 and 4, can also penetrate into the depressions 11 during the melting process in order to establish a positive connection with the outer lateral surface of the insert 6 . After cooling, the thermoplastic material 10 then forms a hard plug, which not only connects the insert 6 to the component 1 in a form-fitting manner but also in a form-fitting manner and therefore could only be removed again in the direction of the central axis 4 with a very high pull-off force.

As FIG. 5 further shows, the insert 6 is provided at its lower end with a chamfer 14 which, when it is introduced into the recess 2 or the body 5, serves as an insertion bevel and centering means and promote the radial displacement of the plasticized material of the body 5 can. In addition, it is possible to provide the insert 6 with an encircling flange 15 at an axial end or in a region which is arranged above its part to be located in the recess 2 and which has a larger external cross section than the dimension E. _a corresponds to FIG. 5, and lies on the broad side 3 of the component 1 during the fastening process. As a result, the fatigue strength of the connection against tilting movements transverse to the central axis 4 can be improved in later use. In addition, the flange 15 can cover the connecting gap and, if necessary, prevent the plastic material from flowing out laterally before the final curing.

Fig. 6 shows an embodiment in which an insert 16 has at its upper end an axially projecting shoulder 17 provided with an externally threaded section, onto which a sonotrode 18 provided with a corresponding internally threaded thread is screwed. After the joining process and after the removal of the sonotrode 18 , the insert 16 therefore forms a mounting element, on the attachment 17 of which, B. a nut or another component provided with a corresponding internal thread can be attached. It is clear that the bore 8 and the internal thread 7 ( FIG. 4) could also be formed on an extension of the insert 6 projecting beyond the component 1 . Otherwise, the arrangement and the procedure in the exemplary embodiment according to FIG. 6 correspond to those according to FIGS. 1 to 5.

In the embodiment according to FIG. 7, there is a difference from FIGS. 1 to 5 in that a component 19 made of a composite construction is used, in which, for. B. a metallic-cellular material 20 is coated on both sides with a cover layer 21 made of metal or another material. Otherwise, this embodiment corresponds to that of FIGS. 1 to 5.

Instead of an internal or external thread section, the inserts 6 , 16 can alternatively also be provided with internal bores with grooves elongated parallel to the central axis 4 for receiving spring pins or, in the manner of stud bolts, with cylindrical projections which have cross bores for receiving dowel pins or the like. The particular form of the insert 6 , 16 depends on the needs of the individual case. In addition, it is clear that the properties or features of the insert 6 , 16 (e.g. outer cross section E _a in FIG. 5) that are important for the joining method and explained above (only) the part to be introduced into the recess 2 or to come to lie therein relate, while an additional section of the insert 6 protruding from the recess 2 after the joining process has ended can be designed essentially freely. As shown in FIG. 4, the insert 6 can, however, also be so short that it completely disappears in the recess 2 , in particular if it does not have a flange 15 .

A further embodiment of the invention provides for the recess 2 and / or at least the outer circumferential surface of the section of the insert 6 , 16 located in the recess 2 to be non-circular (for example oval or angular), in order to thereby increase the rotationally symmetrical shape To achieve anti-rotation. In addition, the recess 2 could completely penetrate the component 1 , in which case the component 1 would have to be placed on a suitable surface when the joining process was carried out, which would generate a counterpressure counter to the force F.

The component 1 and the material 20 of the component 19 can be made of materials suitable for lightweight structures such as. B. aluminum, steel and magnesium foams and other metals with high porosity. However, other materials can also be used, provided that they are not adversely affected by the sonotrodes 9 , 18 acting on them with ultrasonic vibrations. In contrast, for the body 5 preferably thermoplastic materials such. B. polyamide (PA), polycarbonate (PC) or acrylonitrile butadiene styrene (ABS) are used, which are easily plasticized by ultrasonic energy. The inserts 6 , 16 should finally consist of a metal or a metal alloy, although other, sufficiently hard and non-thermoplastic fusible plastics would also be suitable.

The invention is not limited to the exemplary embodiments described, which can be modified in many ways. This applies in particular to the dimensions and geometric shapes of the various parts described. It should also be noted that the outer contour of the section of the insert 6 , 16 inserted into the recess 2 does not have to be identical to the inner contour of the peripheral wall surrounding the recess 2 . It is only necessary that the body 5 has a sufficiently large volume in order to fill the space between the recess wall and the outer lateral surface of the insert 6 , 16 as completely as possible, ie in terms of volume. For this purpose it would also be possible to design the body 5 essentially solid and instead to design the insert 6 , 16 as a hollow body, at least on its underside, so that excess thermoplastic material can be accommodated in a cavity of the insert. In addition, the axial height of the body 5 could also be smaller than the depth of the recess 2 . Furthermore, it would be possible to insert the body 5 and the insert 6 , 16 into the recess 2 at the same time by the body 5 z. B. formed as a hollow body and optionally with a slight press fit on the insert 6 , 16 until it z. B. from below against the flange 15 ( Fig. 5). In this case it would even be possible to choose the dimension K _a ( FIG. 5) slightly larger than the dimension A _i . Combinations of these two variants are also possible. It would of course also be possible to dimension the axial length of the portion of the insert 6 coming into the recess to be shorter than the depth of the recess 2 measured in the axial direction. Furthermore, the sonotrode 9 , 18 could be coupled to the insert 6 , 16 by means other than those described. Finally, it goes without saying that the various features can also be used in combinations other than those shown and described.

Claims (9)

1. Method for attaching an insert ( 6 , 16 ) that can be used as a mounting element to a component ( 1 , 19 ) made of a lightweight material, in particular a metallic-cellular material, by providing the component ( 1 , 19 ) with a recess ( 2 ), the insert ( 6 , 16 ) is at least partially inserted into the recess ( 2 ) and the component ( 1 , 19 ) and the insert ( 6 , 16 ) are then firmly connected to one another by the use of ultrasonic energy, characterized in that the insert ( 6 , 16 ) or a section of the insert ( 6 , 16 ) introduced into the recess ( 2 ) with the aid of a body ( 5 ) made of thermoplastic material which is also inserted into the recess ( 2 ) and plasticized by the ultrasound energy and / or in a form-fitting manner with the peripheral wall of the component ( 1 , 19 ) delimiting the recess ( 2 ). 2. The method according to claim 1, characterized in that the body made of thermoplastic material ( 5 ) in the recess ( 2 ) introduced, the insert ( 6 , 16 ) attached to a sonotrode ( 9 , 18 ) and with this in the direction of Recess ( 2 ) is advanced and the sonotrode ( 9 , 18 ) for plasticizing the body ( 5 ) is set in ultrasonic vibrations. 3. The method according to claim 1 or 2, characterized in that the body made of thermoplastic material ( 5 ) is provided with such an oversize that plasticized when inserting the insert ( 6 , 16 ) or a portion thereof in the recess ( 2 ) thermoplastic material is radially displaced in cavities in the peripheral wall of the component ( 1 , 19 ). 4. The method according to any one of claims 1 to 3, characterized in that the insert ( 6 , 16 ) is provided on its outer surface with at least one intended for receiving thermoplastic material recess ( 11 ). 5. The method according to claim 4, characterized in that the recess ( 11 ) is formed by a notch, groove or recess machined into the jacket surface. 6. The method according to any one of claims 1 to 5, characterized in that the body made of thermoplastic material ( 5 ) is designed as a sleeve-shaped hollow body. 7. The method according to any one of claims 1 to 6, characterized in that at least one portion of the insert ( 6 , 16 ) to be inserted into the recess ( 2 ) is designed as a sleeve-shaped hollow body. 8. The method according to any one of claims 1 to 7, characterized in that the insert ( 6 ) for receiving a fastening means and / or the sonotrode ( 9 ) has an axial recess ( 8 ). 9. The method according to any one of claims 1 to 7, characterized in that the insert ( 16 ) has an axially projecting, for receiving a fastener and / or the sonotrode ( 19 ) certain approach ( 17 ).