DE102014001690A1 - Method for joining a metal component with a plastic component - Google Patents

Abstract

The invention relates to a method for joining a metal component (1) to a plastic component (3) made of a fiber-reinforced plastic, in which the two components (1, 3) are glued together in a first joining step (b) to produce a material connection (I ). According to the invention, the two components (1, 3) are connected to one another in a form-locking manner by means of electromagnetic pulse transformation in a second joining step (d) in order to produce a positive connection (II).

Description

The invention relates to a method for joining a metal component with a plastic component made of a particular fiber-reinforced thermoplastic according to the preamble of claim 1 and a component connection, which can be produced by means of the joining method.

With regard to a lightweight construction, hybrid connections are used in vehicle construction, in which metal sheet metal parts are connected with fiber composite plastic components in a joining process. Such a fiber composite plastic component has reinforcing fibers of, for example, carbon embedded in a matrix material. The matrix material is in common practice a thermoplastic or a thermosetting plastic.

In a generic joining method, the above-mentioned hybrid compound is ensured by an adhesive bond, in which the two joining partners are glued together over a large area to produce a fabric connection.

Alternatively and / or additionally, positive-locking connections between the two joining partners are also known. However, these have the following manufacturing disadvantages: For example, auxiliary joining elements are required when riveting or screwing, which causes additional costs and additional component weight. In addition, pressing tools (for example, a punch during riveting) are required, which are subject to wear in mass production. In addition, such mechanical joining methods lead to fiber damage in the plastic component, for example through a drill hole during riveting. As a result, the performance of the component connection is reduced, for example under dynamic load. Furthermore, certain materials (for example, the titanium alloy Ti-6Al-4V) have no or only a limited cold workability, which can result in the mechanical joining process cracks in the metal. Due to the manufacturing technology comparatively low joining / deformation rate in mechanical joining processes (for example, semi-hollow punching rivets) may also result in the problem that the reshaped material springs back. In particular, when bonding the two components process parameters, such as the curing time or the curing temperature are also to be considered, with immediately after an adhesive connection, the connection strength is still very low, which, further handling of the component connection is limited.

Generally, for example, from the CN 202861226 U known to connect sheet metal parts by electromagnetic pulse forming form-fitting together. Such electromagnetic pulse transformation is also referred to as magnetic forming and is an electrodynamic forming process in which sheet metal parts of electrically conductive material are bonded together using a pulsed magnetic field by cold working. The metal parts to be joined together are positioned in the vicinity of a magnetic coil and connected to each other by the force of the pulsed magnetic field with very high intensity. To generate a suitable magnetic field pulse, the magnetic coil is subjected to a current pulse of a few 100 kA. To generate such a high current pulse previously capacitors can be charged for a period of a few seconds to then act on the solenoid coil within a short pulse period with an excitation current pulse of more than 100 kA. The short magnetic field pulse causes a, the magnetic coil facing sheet metal part is moved at high speed against the other, facing away from sheet metal part. In this case, a sheet metal part meets at very high speed, about 300 m / s, on the other sheet metal part, so that local mixing processes occur on the material surface, whereby the sheet metal parts are interconnected.

The object of the invention is to provide a method for joining a metal component with a plastic component made of, in particular, a fiber-reinforced thermoplastic, which in terms of production technology simply provides a perfect component connection that can be used for mass production.

The object is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the subclaims.

According to the characterizing part of patent claim 1, in addition to the material connection known from the prior art, a positive connection between the two joining partners, in which the two components are connected to each other by means of electromagnetic pulse shaping. Compared to conventional mechanical form-locking connection processes, no additional mechanical auxiliary elements are required, especially in the case of electromagnetic pulse transformation, and no wear of a stamping tool results. In addition, fiber damage in the plastic component can be reliably prevented. Furthermore, in the case of pulse forming, it is also possible to transform restrictedly cold-workable metals without macrocracks. In comparison to the common mechanical joining methods, the electromagnetic pulse transformation takes place with a considerably higher joining / deformation speed. As a result, it is also possible to deform alloys which are not suitable for common mechanical joining methods. In addition, due to the greatly accelerated reshaping, only a minimal springback effect can occur, it being possible to work with high precision and re-accuracy.

The combination of the first joining step, in which a material connection takes place, with the second joining step, in which the electromagnetic pulse transformation takes place, results in a component connection with extremely high connection strength.

The electromagnetic pulse transformation carried out in the second joining step takes place after the first joining step, in which the two components are glued together. The form-fitting connection can take place immediately after the first joining step, that is, when not yet cured adhesive bond. In this way, when the adhesive bond has not yet hardened, a high bond strength can already be achieved and the further processing can be carried out reliably - despite not yet fully cured adhesive bond. Due to the fact that no springback is to be feared, the deformed connection remains permanently dimensionally stable for an ideal curing of the adhesive bond.

In order to make the second joining step process-reliable, the plastic component is to be brought into a deformable state before the electromagnetic pulse transformation is carried out. According to a first embodiment, the production of the plastic component may already be designed such that the plastic component already in the manufacturing state, that is already after its completion has a sufficiently large flowability with which the plastic component is non-destructively deformable in the second joining step. However, this is achievable only with manufacturing technology high effort and correspondingly difficult to implement.

In contrast, in a preferred second embodiment, the second joining step may be preceded by a heating step, with which the thermoplastic of the plastic component is brought into the deformable state under the action of heat. By way of example, the plastic component can be largely plasticized in the heating step.

When carrying out the electromagnetic pulse transformation in the second joining step, a force pulse can be exerted on the sheet metal part by the magnetic coil of a joining device with which the material of the sheet metal part is driven into the material of the plastic component. As a result, the form-fitting connection between the two components is produced under material deformation as well as the formation of undercuts. The material of the metal component is thereby driven into the plastic component, that a residual material strength is maintained in the plastic component. In this way it is ensured that the remote from the force pulse of the component connection is still covered over the entire surface of the plastic material of the plastic component. The material of the sheet metal part therefore does not pierce the plastic component.

In order to carry out the electromagnetic pulse transformation, a die can be provided as an abutment for the component connection, which is to be arranged on the side of the component connection facing away from the magnetic coil. In order to increase the form-locking connection, the die can have a cavity into which the material of the two components can flow when the force pulse is acted upon. The material displacement takes place with the formation of an impression on the side of the component connection facing away from the die.

According to one embodiment, in the first joining step, in which the adhesive bond is produced, the two components are joined together with the interposition of an additional adhesive layer. The adhesive layer may preferably be made of a material-like or material-identical with the thermoplastic of the plastic component. The adhesive layer not only creates the material bond between the two components, but also serves the electrical insulation and the seal between the two components.

To prepare the first joining step, in which the adhesive bond between the components takes place, a heating step can be carried out, in which the plastic component and / or the adhesive layer is melted at the contact surfaces to increase the adhesion.

The cavity of the die can also be designed such that the material deformation of the component connection is selectively adjustable. By way of example, the die cavity may have at least one undercut with respect to the effective direction of the force pulse into which the material of the component connection can flow. For demolding of the component connection, the die can be designed, for example, in two parts, whereby, for example, two matrices can be moved apart in a demolding perpendicular to the direction of force-effective direction.

The advantageous embodiments and / or developments of the invention explained above and / or reproduced in the subclaims can - except, for example, in the case of clear dependencies or incompatible alternatives - be used individually or in any combination with each other.

The invention and its advantageous embodiments and further developments and advantages thereof are explained in more detail below with reference to drawings.

Show it:

1 in a partial sectional view of the component connection according to the first embodiment;

2 Views, the process steps for the preparation of in the 1 illustrate component connection shown;

3 in a view corresponding to 1 a component connection according to the second embodiment, as well as

4 in a view corresponding to 3 the process steps for the preparation of in the 3 shown component connection.

In the 1 a hybrid connection according to a first embodiment is shown, in which a sheet metal part 1 with a plastic board 3 made of a fiber-reinforced thermoplastic. The two components 1 . 3 are both by a material connection I as well as by a positive connection II connected with each other. In the material connection I are the facing contact surfaces 5 the plastic board 3 and the sheet metal part 1 directly, ie without interposition of an additional adhesive layer, glued together. The positive connection II is generated by an electromagnetic pulse transformation, in which on the, the plastic board 3 opposite side of the sheet metal part an impression 7 with an embossing depth .DELTA.t is introduced, with the formation of undercuts 9 in the material of the softer plastic board 3 into which the material of the sheet metal part 1 is relocated. On the, the imprint 7 opposite side of the plastic board 3 results in a shape 11 in which the plastic board 3 the sheet metal part 1 covered with a residual material thickness Δr.

The following are based on the 2 the process steps to manufacture in the 1 described component connection described. Thus, according to the 2 in a first process step a, the plastic board 3 provided as a separate component and by means of a heating element 13 at the contact surface 5 to the metal component 1 heated to the thermoplastic in the area of the contact surface 5 melt. Subsequently, in a second process step b, the two joining partners, that is the sheet metal part 1 and the plastic board 3 , glued together under pressure to produce the adhesive connection I , The component connection thus formed is heated again in process step c to the thermoplastic of the plastic board 3 to spend in a workable state. In a technical realization, the process steps a and c can be combined to form a common process step. That means it will be the plastic board 3 heated, so that their surface melts and is deformable over the cross section. The heating of the thermoplastic can also be done indirectly by heat conduction due to the heating of the sheet (for example, by induction).

Subsequently, the heated component connection is moved in process step d in a forming device, in which the component connection first on a die 16 is filed. The plastic board 5 is arranged on the die side, while the sheet metal part 1 a magnetic coil 15 is arranged facing. By means of the magnetic coil 15 In the forming process, a momentary force F on the sheet metal part 1 exercised, with which the material of the sheet metal part 1 in the material of the plastic board 3 is driven. This takes place under material deformation as well as formation of the undercuts 9 ( 1 ), while maintaining the residual material thickness Δr in the plastic board 3 , The in the direction of action of the force pulse F with respect to the magnetic coil 15 arranged die 16 has a cavity 17 on. Upon application of the force pulse F, the material of the component connection is in the cavity 17 the matrix 16 driven, resulting in the above-mentioned shape 11 results.

In the 3 a hybrid connection according to the second embodiment is shown. In contrast to the first embodiment, the material connection I not by a direct bonding of the plastic board 3 achieved with the sheet metal part, but rather with the interposition of an additional adhesive layer 19 , The adhesive layer 19 is material identical or material similar to the thermoplastic of the plastic board 3 , Like from the 3 As can be seen, the adhesive layer extends 19 over a large area as well as consistently via the local positive connection II time. In this way, the adhesive layer takes over 19 an electrical insulation between the two components 1 . 3 as well as an additional sealing function.

The production of in the 3 The hybrid compound shown is in the 4 illustrated schematically. In contrast to 2 here falls the heating step a away and become the beginning of the process, the plastic board 3 , the sheet metal part 1 and the adhesive layer 19 provided separately from each other (process step b). In process step b, the two joining partners are then 1 . 3 with the interposition of the adhesive layer 19 glued together. To prepare the electromagnetic pulse transformation is in process step c the hybrid connection by means of a further heating element 14 heated so that the thermoplastic material is spent in a formable state. Subsequently, the process step d and e, which are carried out analogously to the first embodiment. In an alternative process control, the process step c and subsequently the process step b can also take place first. The adhesive in the adhesive layer 19 is typically low viscous.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 202861226 U [0005]

Claims (12)

Method for joining a metal component ( 1 ) with a plastic component ( 3 ) of a plastic, in particular fiber-reinforced plastic, in which the two components ( 1 . 3 ) are glued together in a first joining step (b) to produce a cohesive connection ( I ), characterized in that for the production of an additional, in particular local form-locking connection ( II ) the two components ( 1 . 3 ) are positively connected to each other in a second joining step (d) by means of electromagnetic pulse transformation. Method according to claim 1, characterized in that the fiber-reinforced plastic component ( 3 ) is brought into a deformable state before performing the second joining step (d). A method according to claim 2, characterized in that the composition of the plastic component ( 3 ) is designed so that it already in the manufacturing state, that is, after its completion, has a sufficiently large flowability with which the component ( 3 ) is non-destructively deformable in the second joining step (d). A method according to claim 1, 2 or 3, characterized in that the matrix material of the fiber-reinforced plastic part ( 3 ), in which the reinforcing fibers are embedded, is a thermoplastic. A method according to claim 4, characterized in that the second joining step (d) is preceded by a heating step (c), with which the thermoplastic of the plastic component ( 3 ) is brought into the deformable state under the action of heat. Method according to one of the preceding claims, characterized in that in the second joining step (d) in the implementation of the electromagnetic pulse transformation, a force pulse (F) on the sheet metal part ( 1 ) is applied, with which the material of the sheet metal part ( 1 ) in the material of the plastic component ( 3 ) and that under material deformation and / or with the formation of undercuts ( 9 ) the positive connection ( II ) is produced. Method according to one of the preceding claims, characterized in that for carrying out the electromagnetic pulse transformation in the second joining step (d) as an abutment for the component connection a die ( 16 ) provided. Method according to claim 7, characterized in that the die has a cavity ( 17 ), in which the material of the component connection is displaceable under the action of the force pulse (F), to form an impression ( 7 ) on the matrizenabgewandten side of the component connection. Method according to one of the preceding claims, characterized in that in the first joining step (b) with the interposition of an additional adhesive layer ( 19 ) the two components ( 1 . 3 ) are joined together, and that in particular the adhesive layer ( 19 ) material-like or material identical to the matrix material of the plastic component ( 3 ). Method according to one of the preceding claims, characterized in that the first joining step (b) is preceded by a heating step (a), in which the plastic component ( 3 ) and / or the adhesive layer ( 19 ) at the contact surfaces ( 5 ) is melted. Method according to one of the preceding claims, characterized in that the second joining step (d) is carried out during the curing of the adhesive joint produced in the first joining step (b). Method according to one of the preceding claims 6 to 10, characterized in that the cavity ( 17 ) of the die ( 16 ) with respect to the direction of action of the force pulse (F) has at least one undercut into which the material of the component connection is displaceable.

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