WO2010130271A1

WO2010130271A1 - Method for material bonding by means of friction welding using an adhesive

Info

Publication number: WO2010130271A1
Application number: PCT/EP2009/003362
Authority: WO
Inventors: Uwe Reisgen; Markus Schleser; Alexander Harms; Eva Regina Thiele
Original assignee: Rheinisch-Westfälische Technische Hochschule Aachen
Priority date: 2009-05-12
Filing date: 2009-05-12
Publication date: 2010-11-18
Also published as: WO2010130271A8; DE112009004072A5

Abstract

The invention relates to a method for the material bonding of at least two joined parts (1, 2) by means of friction welding, in particular friction stir welding, friction stir spot welding or friction stir seam welding or friction spot welding, wherein the joined parts (1, 2) to be bonded are fixed in relation to each other before the friction welding by an adhesive (4) and, during the subsequent friction welding, the forces and/or moments that occur during the bonding and tend to change the relative position of the joined parts (1, 2) in relation to each other are absorbed by the adhesive (4).

Description

PROCESS FOR CONNECTIVELY CONNECTING WITH FRICTION WELDING USING AN ADHESIVE AGENT

The invention relates to a method for materially joining at least two joining parts by means of friction welding, in particular friction stir welding (FSW) or stirring friction point welding or friction stir welding or friction spot welding.

Welding techniques for integrally joining at least two parts to be joined are well known in the art. Special attention has recently been given to a process in which the energy necessary for bonding is introduced by means of a rubbing process into the parts to be joined.

In the context of the invention, the friction welding process is understood to mean any type of welding in which the welding energy is introduced by rubbing by means of a tool into the parts to be joined. A typical method is agitation friction welding, or stirring friction welding, in which a rotating tool comprises a substantially cylindrical member having a friction shoulder from which a pin protrudes.

Under rotation, the tool is pressed with its pin into the parts to be joined with great force, until the friction shoulder comes to rest on the part or parts and by the effect of rubbing enters energy into the parts to be joined, so that the material piastifiziert the joining ie softens, but does not melt. As a result of a movement of the tool along a path to be welded with respect to the parts to be joined, the pin is moved through the plasticized material of the parts to be joined and stirred in the latter

BESTÄTIGÜNGSKOPIE Movement of the plasticized materials of the joining parts, so that sets a cohesive connection. This method of stirring-friction welding, which can be carried out both as seam and spot welding, has received a high level of attention because it operates below the melting temperatures of the materials involved and thus high-quality joint joints can be created without serious structural changes and resulting therefrom Property changes of the material as in other welding processes.

The invention is equally applicable to the method of Reibpunktschweißens, which is a subspecies of the stirring Reibpunktschweißens, in which the aforementioned pin on the tool in the axial direction relative to the shoulder of the tool is displaceable. This has the particular advantage that at the end of a weld or at the point of a spot weld joint no hole remains in the parts to be joined, which is otherwise typical for the rigid-pin agitation friction welding method.

Accordingly, the method according to the invention can be used both with a rigid and with an axially movable pin, in particular in the case of the stirring-friction welding method described above.

It is perceived as disadvantageous in these known methods that due to the extremely high process forces, which are registered by means of the tool in the Fügeteile, the Fügeteile previously fixed by means of external clamping devices must be fixed to each other stable, so that the joining parts maintain their relative position to each other during the rubbing process , However, the use of such tensioning devices is problematic or space-constrained in some desired applications not possible, especially so that just joining parts that move in the dimensioning of the tool can not be fixed with the usual fixtures in a sufficient manner or only with extreme effort. In so-designed joint connections is usually a complex device construction for fixing the weldments necessary and for special applications, the cost of fixation can be about 1/3 of the total cost.

It is therefore an object of the invention to provide a method for materially bonded connection of at least two parts to be joined by friction welding, in particular the above-mentioned stirring friction welding, which makes the previously used elaborate clamping technology by means of external clamping devices in the joining area completely unnecessary.

The solution to this problem is inventively achieved in that the joining parts to be joined are fixed relative to each other before the friction welding by an adhesive and during the subsequent friction welding by the adhesive the forces occurring during friction welding, in particular agitating friction welding and / or moments that tend to change the relative position of the parts to each other to be completely absorbed.

The essential idea of the invention is thus to render the tensioning devices, which were customary in the prior art, completely dispensable for absorbing the joining forces in the seam area, for which purpose an adhesive is used. For example, it can also be achieved that joining parts can be connected to one another by the method of friction welding, in particular stirred friction welding, which according to the original known prior art could not be tensioned with the hitherto known clamping devices, in particular due to geometric restrictions. The method according to the invention therefore makes not only the usual clamping tools dispensable, but opens up further fields of application that could hitherto not be processed by the use of the usual clamping technology.

According to the invention, it is therefore preferred to choose an adhesive in which the adhesion forces between adhesive and adherends and / or between adhesives and auxiliary elements and the cohesive forces in Adhesives are set to be greater than the forces acting in the process of joining (friction welding) between the parts to be joined or between a joining part and an auxiliary element. Accordingly, when selecting appropriate adhesives, tensioning tools previously used are dispensable since the forces acting on are completely removed by the adhesive and thus the parts to be joined remain stable in position during the implementation of a connection by friction welding, in particular stirring friction welding.

In principle, all adhesives which are suitable for absorbing the forces and moments arising during the welding process can be used in this process.

This may be, for example, two-component adhesives, which would however be associated with a disadvantage in that they require a certain setting time in order to achieve sufficient strength and thus are suitable for taking up forces and moments only after this minimum required time.

The use of reactive adhesives, such as from

Two-component adhesives, however, can continue to offer advantages, namely, if by the registered by the friction process welding such a reactive adhesive and thus the connection between the joining parts, which is given in addition to the pure Reibschweißverbindung also by the adhesive, a particularly high stability.

In a particularly preferred application, for example, pressure-sensitive adhesives or contact adhesives can be used, for example as an adhesive tape or in liquid form between the parts to be joined or a joining part and an auxiliary element, wherein such pressure-sensitive adhesives or contact adhesives reach their necessary initial strength immediately immediately when joining the parts to be bonded. According to the invention, it can be provided in one embodiment, for example, two joining parts to arrange each other at least partially overlapping, wherein an adhesive, for example a liquid adhesive or an adhesive in the form of an adhesive tape, in the overlapping region of the joining parts is arranged.

In another embodiment, it may also be provided to abut two joining parts, wherein an adhesive between a first joining part and an auxiliary element and between a second joining part and a, preferably the same auxiliary element is arranged. Here, an auxiliary element serves in particular to achieve the stability of the two parts to each other, which would otherwise not be given only by an adhesive bond between the abutting surfaces of the parts to be joined. An auxiliary element can therefore serve, for example, only temporarily as a contact element or supporting element in the welding process in order to guarantee the positional stability of the parts to be joined during the execution of the welded connection.

In conjunction with an auxiliary element, it can therefore be provided that this is not involved in the welding process itself, so only the two joining parts, which are interconnected by the auxiliary element, are connected by the method of friction welding.

In another embodiment, it may also be provided that the two joining parts are connected to one another and to the auxiliary element. In such an embodiment, it may for example also be provided in addition that an auxiliary element is removed by machining after performing the welding operation. Here, the auxiliary element has the particular advantage that a recess which is produced at the end of a weld by a pin of a stirring friction tool, can be arranged in the material thickness of the auxiliary element and thus can be completely removed by the cutting removal of the Hiifselementes without the between the actual parts to be welded existing existing negative influence. It can be that way by means of an auxiliary element surface flush welded joints are also produced with conventional stirring reaming tools with a fixed pin.

In a further arrangement, it can also be provided that two joining parts are arranged in abutment, with an adhesive being arranged between the opposite abutting sides of the joining parts. Such an arrangement can be chosen, for example, if the butt-facing sides or surfaces of the joining parts provide a sufficient size to achieve sufficient absorption of the process forces and / or moments by arranging an adhesive between these surfaces / sides, without that it requires another auxiliary element.

In all of these aforementioned embodiments and especially in the at least partially overlapping welding of two parts to be joined, it may be provided in a possible application that an adhesive is arranged below / below the later joining seam / the later joining point. In such a method, therefore, the adhesive is directly in the region of the subsequent connection, so it can be made in particular in an overlapping welding through the adhesive through the welded joint.

It is felt to be particularly advantageous if the adhesive is chosen so that it is displaced during joining from the region of the compound, so the friction weld or Reibschweißpunktes. For example, the adhesive may be chosen to have sufficient strength in the cold temperature range to absorb the process forces, but soften the additional heat in the immediate area of the joint where the welding tool introduces the frictional heat into the adherends. that a displacement from the connection area is made possible. In another embodiment, it may also be provided that an adhesive is arranged at a distance from the region of the subsequent connection / weld / weld point. For example, here the adhesive can be arranged on one side only at a distance or else in another embodiment on both sides at a distance to a later connection, in particular a longitudinally extending connection seam. This embodiment has the advantage that a sufficient fixation of the joining parts is given relative to each other along the connection to be performed, but in the actual connection region no adhesive is present.

In particular, in the case of butt welding, it may be provided that, when the adhesive connection between the parts to be joined takes place over the opposing abutment sides, the adhesive is at a distance from the surface of the parts to be joined, so that it lies below a submerged welding tool with friction shoulder and pin during welding the lowest end of the pin is arranged. The adhesive thus has at any time during a welding process at a distance from the weld and does not affect them.

Just here, and in principle in all applications in which an adhesive is used for fixing the joining parts relative to each other, an adhesive in addition to the advantage of clamping tool-free fixation of the parts to each other still bring the further advantage that any gaps between the parts to be joined after Performing a weld by the adhesive can be filled and thus the adhesive seals such gaps, in particular whereby also a tendency to corrosion is reduced. In this case, the adhesive can be arranged so that it enters by displacing during the friction welding in one or more remaining column.

In one embodiment of the invention, it may be provided that the adhesive surface between two parts to be joined or a joining part and a Auxiliary part is set smaller in the direction of a connection to be performed. This method step is based on the consideration that only initially, in particular when no joining connection has yet been produced by friction welding, the forces and moments introduced by friction welding into the parts to be joined must be completely and exclusively absorbed by the adhesive.

However, if a first portion of a Reibschweiß- in particular a stirring Reibschweißverbindung already formed, so this contributes already partially welded portion for force and moment recording with, so that accordingly the forces and moments no longer need to be completely absorbed by the adhesive alone. There is therefore the possibility of reducing the adhesive surface in the direction of a connection to be made, for example a weld, which means that the adhesive area in the welding direction can be reduced while the adhesive layer thickness remains the same.

In another application, it may also be provided that, together with an adhesive, at least one welding additive is arranged in the region of a later welded joint. For example, such a welding additive may be contained directly in the adhesive. In such an arrangement, it can be provided, for example, as described above, that the adhesive is also arranged directly in the connection region between two joining parts. It can thus be effected, for example, that a welding additive is introduced from the adhesive in the (stirring) friction weld and thus in the mixed materials of the two parts to be joined. For example, this can alloy the weld.

In the case of a liquid adhesive, provision can be made, for example, for a welding additive to be present, for example, as a particle within the liquid adhesive, and for example as an adhesive bead or adhesive dots as a result of the application is applied simultaneously with the adhesive between two parts to be joined or a joining part and an auxiliary element.

When using an adhesive in the form of an adhesive tape or liquid adhesive it may be provided that a welding additive is arranged along the longitudinal extent of the adhesive tape, e.g. occupies a web region, in particular a web region between two adhesive web regions of the adhesive. Thus, such an adhesive tape may accordingly have a structure in which a web-shaped welding additive is surrounded on the right and left sides by adhesive areas. An arrangement can thus be achieved in which such an inventive adhesive tape is arranged between two parts to be joined, for example in the case of overlapping joining or also between a joining part and an auxiliary element, namely e.g. in such a way that the adhesive areas connect the parts to be joined or the joining part with the auxiliary element and the web area of the welding additive comes to lie directly in or below the later connecting area of the joining parts. Thus, a welding additive from such an adhesive tape can be entered directly into the weld, without the adhesive portion of such an adhesive tape influencing the quality of the welded joint.

The inventive method, as described above, not only conventional clamping tools are unnecessary, but it also opens up applications that were previously not available with the usual clamping tools.

For example, there is the possibility of one of the joining parts as a sheet, in particular a very thin-walled sheet or a foil, for example, is given with a thickness of less than 1 mm. Here was the disadvantage of the known in the prior art friction or agitation friction welding that it came by touching the Reibschulter of the tool to warping of the joining part, ie in particular the thin sheet or the film due to the low stability or rigidity of the joining part and insufficient attachment of the Joining parts by the clamping tools in the area of the weld to be performed.

The method according to the invention now opens up the possibility here of attaching such critical adherends, such as sheets and thin foils, to one another with an adhesive, in particular in such a way that the adhesive extends completely adjacent to the subsequent weld seam, such a foil or such a thin sheet metal supported or even the adhesive is completely arranged under such a sheet or a film on the joint area. Due to this type of bonding, warping in or adjacent to the joining area can be completely avoided, and thus for the first time such particularly thin joining parts are connected to one another.

The method according to the invention is particularly suitable for joining metals, for example those metals which can not or only with difficulty be connected with classical welding methods, such as light metals, e.g. Aluminum or magnesium. Also alloys, such as e.g. Brass are to be welded by such a method. There is also the possibility of non-material joining parts, e.g. Aluminum and stainless steel or metal and plastic together, as well as basically non-metallic materials such. Thermoplastic plastics in the parts to be joined.

An adhesive may in principle be applied manually or automatically, e.g. liquid, for example as a bead, flat, punctiform or by spraying, as well as by means of an adhesive tape.

The method according to the invention as well as the arrangements of the parts to be joined and adhesives used in this case will be explained in more detail with reference to the following figures. Show it:

Figure 1 overlap welds

Figure 2 butt welds FIG. 3 orbital welds

FIG. 1 shows in FIG. 1 a) a possibility of overlap welding, in which two parts 1 and 2 are arranged in a partially overlapping manner, wherein in the overlapping region completely, but preferably also directly in the welding region 5, i. the area in which the rubbing process is performed with a stirring-friction tool 3, an adhesive 4 is arranged.

This adhesive 4 may be any suitable adhesive capable of completely absorbing the forces and moments involved and thus guaranteeing the positional stability of the adherends 1 and 2 to each other during the performance of the agitation friction welding process.

It is essential here, as in principle in all conceivable method steps according to the invention, that an inserted adhesive 4 has sufficient strength even before carrying out the friction-welding or agitating friction-welded connection in order to absorb the forces and moments acting on it and thus the positional stability of the joining part 1 and 2 to secure.

In the case of FIG. 1a), it is therefore such that by carrying out the stirring / friction-welding connection with the tool 3, the adhesive 4 can be displaced out of a connection region 5 without being thermally damaged. A thermal damage can be avoided here in particular because the friction energy is only sufficient to achieve a plastification of the involved joining parts 1 and 2, but a melting is avoided. The resulting temperature during joining is low enough to avoid damage to the adhesive 4.

On the other hand, FIG. 1b) shows an arrangement with overlapping joining parts 1 and 2, in which adhesive 4 is arranged on both sides of a connection zone 5, in which the agitating friction-welded connection is made. It can be avoided so that adhesive 4 enters the welding zone 5 and in particular, no displacement of the adhesive 4 from the welding zone 5 is required.

FIG. 1c) shows a further possibility of fixing the joining parts 1 and 2 by means of an adhesive 4, in which this adhesive 4 is arranged in the overlapping region only to one side of the joining region 5. Such an arrangement may be advantageous if, for example, the joint connection 5 is to be carried out close to one of the joining parts 1 or 2. Here, as well as in all other variants of the method, the adhesive may also have the advantage that a possible gap between the joining parts 1 and 2 is closed or sealed by this adhesive 4.

FIG. 2 shows in several illustrations the production of butt welds. Here, in an embodiment according to FIG. 2 a, it can be provided, for example, that two joining parts 1 and 2 are abutted against each other, here with a slight, possibly unavoidable, distance of the abutting sides, wherein the joining part 1 is connected to an auxiliary element 6 by means of an adhesive 6 As a result of the auxiliary element 6, the joining part 1 and the joining part 2 are fixed relative to one another in a positionally stable manner only by means of an adhesive 4 and it is possible to weld into the joint area 5 by means of the agitating friction tool 3 perform. Here, the implementation of the welded joint may be such that only joining part 1 and 2 or even the joining part 1 and 2 and auxiliary element 6 are connected to each other. The use of an auxiliary element 6 is particularly advantageous here when an adhesive bond over the relatively small-area abutment sides of the joining parts 1 and 2 is not sufficient strength of an adhesive bond between the Divide 1 and 2 would result.

In contrast, Figure 2b shows an embodiment with two joining parts 1 and 2, which are connected at their abutting sides by means of an adhesive 4 are. It is in this embodiment by two hollow profiles with square cross-section, this example is to be understood as non-limiting.

In this embodiment, a sufficient positional stability can be achieved by the adhesive 4 between the abutting sides of the joining parts 1 and 2. In this case, provision may be made for the adhesive 4 (not illustrated here) to be arranged at a distance from the connection region 5 such that the upper edge of the adhesive 4 lies below the immersed pen tip of the stirring tool 3. It is also possible, as shown here, apply the adhesive 4 over the entire surface over the entire impact surface, if the presence of an adhesive in the connection region 5 is not considered to be disadvantageous.

FIG. 2c) shows a variant in which two U-profiles are welded on impact and an auxiliary element 6 serves for fixing the parts to be joined. The implementation of gluing and welding is otherwise equivalent to FIG. 2a).

FIG. 3 shows a further embodiment of a possible welded joint, in which joining part 1 and joining part 2 are abutted against one another in this illustration and here again, for example, are made out as hollow profiles. Regardless of the type of embodiment of the joining parts 1 and 2, it may be provided that an auxiliary element 6 is provided overlapping the butt joint, wherein in each case between joining part 1 and auxiliary element 6 and also joining part 2 and auxiliary element 6, an adhesive 4 is applied.

In this embodiment, a welded connection is made by immersing the agitating reaming tool 3 through the auxiliary member 6 through into the joining parts 1 and 2 or the butt joint of the two. In this case, the adhesive 4 can be arranged such that it is arranged in the joining region or at a distance thereto. The auxiliary element 6 is thus arranged between the joining parts 1 and 2 and the tool 3. It is achieved so that a welded joint between joining part 1 and 2 and auxiliary element 6 results, with the possibility of removing the auxiliary element 6 after performing the weld, which here has the advantage that any, remaining through the pin of the stirring friction tool at the end of the weld hole as well is removed and results in a flush to the parts 1 and 2 flush welded joint.

Claims

claims

1. A method for cohesive joining of at least two joining parts (1, 2) by friction welding, in particular stirring friction welding or stirring Reibpunktschweißen or stirring Reibnahtschweißen or Reibpunktschweißen, characterized in that the joining parts to be joined (1, 2) before the friction welding an adhesive (4) are fixed relative to one another and during the subsequent friction welding by the adhesive (4) the forces occurring during connection and / or moments which tend to change the relative position of the joining parts (1, 2) to each other, are collected.

2. The method according to claim 1, characterized in that the

Adhesive forces between adhesive (4) and adherends (1, 2) and / or at least one auxiliary element (6) and the cohesive forces in the adhesive (4) are set to be greater than the forces acting in the process of joining forces between the joining parts (1, 2) or between a joining part (1, 2) and at least one auxiliary element (6).

3. The method according to any one of the preceding claims, characterized in that two joining parts (1,2) are arranged overlapping each other, wherein an adhesive (4) in the overlapping region of the joining parts (1, 2) is arranged.

4. The method according to any one of the preceding claims, characterized in that two joining parts (1, 2) are arranged in abutment, wherein an adhesive (4) between a first joining part (1) and an auxiliary element (6) and between a second joining part ( 2) and the same auxiliary element (6) is arranged, in particular wherein only the two joining parts (1, 2) are interconnected.

5. The method according to any one of the preceding claims, characterized in that two joining parts (1, 2) are arranged in abutment, wherein an adhesive (4) between the opposite abutting sides of the joining parts (1, 2) is arranged.

6. The method according to claim 3 to 5, characterized in that a

Adhesive (4) is arranged below / below the subsequent joining seam (5) / the subsequent joining point, in particular wherein the joining of the joining parts (1, 2) through the adhesive (4) is carried out.

7. The method according to claim 3 to 6, characterized in that the

Adhesive (4) is displaced upon connection from the region of the compound (5).

8. The method according to claim 3 to 5, characterized in that a

Adhesive (4) is arranged at a distance from the region of the subsequent connection (5), in particular to one or both sides of a later connecting seam (5).

9. The method according to claim 4, characterized in that the two joining parts (1, 2) with each other and with the auxiliary element (6), in particular with a tool (3) from the side of the auxiliary element (6) are connected, in particular after joining the auxiliary element (6) is removed by cutting, in particular up to a level / height of the joining parts (1, 2).

10. The method according to any one of the preceding claims, characterized in that the adhesive surface between two parts to be joined (1, 2) or a joining part (1, 2) and an auxiliary part (6) in the direction of the connection to be performed (5) is set smaller.

11.Verfahren according to any one of the preceding claims, characterized in that at least one of the joining parts (1, 2) is a sheet or a film, in particular with a thickness of less than 1 mm.

12. The method according to any one of the preceding claims, characterized in that together with an adhesive (4) at least one welding additive is arranged in the region of a later connection (5), in particular a welding additive which is contained in the adhesive (4).

13. The method according to any one of the preceding claims, characterized in that as adhesive (4) a pressure-sensitive adhesive or contact adhesive is used as an adhesive tape or in liquid form.

14. The method according to any one of the preceding claims, characterized in that as adhesive (4) a reactive adhesive is used, which cures by introducing the frictional heat during bonding.