Method for Providing a Component Assembly for a Motor Vehicle, and Component Assembly for a Motor Vehicle

Abstract

A method for providing a component assembly for a motor vehicle includes inserting a weldable element into an opening of a first metal sheet such that a joint is defined between the weldable element and the first metal sheet and such that a reservoir connected to the joint is preserved at a first side of the first metal sheet that faces a second metal sheet where the reservoir is open in a direction toward the second metal sheet. The method further includes applying an adhesive to the first side of the first metal sheet and/or to the second metal sheet and placing the second metal sheet against the first metal sheet and the weldable element and welding the second metal sheet to the weldable element.

Claims

1.-10. (canceled)

11. A method for providing a component assembly for a motor vehicle, comprising the steps of: inserting a weldable element into an opening of a first metal sheet such that a joint is defined between the weldable element and the first metal sheet and such that a reservoir connected to the joint is preserved at a first side of the first metal sheet that faces a second metal sheet, wherein the reservoir is open in a direction toward the second metal sheet; applying an adhesive to the first side of the first metal sheet and/or to the second metal sheet; and placing the second metal sheet against the first metal sheet and the weldable element and welding the second metal sheet to the weldable element.

12. The method according to claim 11, wherein the weldable element terminates flush with the first side of the first metal sheet that faces the second metal sheet and completely covers an opening cross section of the opening.

13. The method according to claim 11, further comprising the step of placing a vacuum suction device against a second side of the first metal sheet that faces away from the second metal sheet after the step of placing the second metal sheet against the first metal sheet, wherein the vacuum suction device covers the joint and wherein adhesive in the reservoir is drawable from the reservoir into the joint by the vacuum suction device.

14. The method according to claim 11, wherein the second metal sheet is welded to the weldable element by resistance spot welding.

15. The method according to claim 14, further comprising the step of predetermining a temperature for the joint and adjusting a current flow of the resistance spot welding to result in the temperature.

16. The method according to claim 15, further comprising the step of selecting the adhesive based on the temperature, wherein a boiling point of adhesive substance proportions of the adhesive is below the temperature.

17. The method according to claim 11, wherein the adhesive contains magnetizable particles and/or a propellant and/or a gelling agent.

18. The method according to claim 11, further comprising the step of heating the component assembly in a heating apparatus after the step of applying the adhesive.

19. A component assembly for a motor vehicle, comprising: a metal sheet with an opening; and a weldable element disposed in the opening such that a joint is defined between the metal sheet and the weldable element; wherein a reservoir that is open in a direction toward a side of the metal sheet is preserved at the side of the metal sheet and is connected to the joint.

20. The component assembly according to claim 19, wherein the reservoir is an annular groove.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0017] The single FIGURE shows a cross section of a component assembly for a motor vehicle, in which an aluminum sheet as a first metal sheet with a steel sheet as a second metal sheet are connected in the context of a resistance element welding operation using an auxiliary means, which is a weldable element, and the weldable element and the steel sheet are electrically insulated against the aluminum sheet by means of an adhesive.

DETAILED DESCRIPTION OF THE DRAWING

[0018] The single FIGURE shows a component assembly 1 for a motor vehicle. The component assembly 1 comprises an aluminum sheet 2 and a weldable element 4 which is inserted into an opening 3 of the aluminum sheet 2. The weldable element 4 is an auxiliary means, via which the aluminum sheet 2 can be secured to an additional component. In this instance, the component assembly 1 further comprises a steel sheet 5. The aluminum sheet 2 can be secured to the steel sheet 5 via the weldable element 4 as an auxiliary means. The steel sheet 5 can be retained via an adhesive layer on the aluminum sheet 2. Additionally, the steel sheet 5 can be resistance spot welded to the weldable element 4, whereby a materially engaging connection between the weldable element 4 and the steel sheet 5 is provided. In order to produce the component assembly 1, consequently, the weldable element 4 is introduced into the opening 3 of the aluminum sheet 2, wherein a joint 7 is delimited between the aluminum sheet 2 and the weldable element 4. Subsequently, the adhesive 6 is applied to a side 8 of the aluminum sheet 2 facing the steel sheet 5 and/or the steel sheet 5 and the steel sheet 5 is placed against the side 8 of the aluminum sheet 2 facing the steel sheet 5. By placing the steel sheet 5 against the side 8 of the aluminum sheet 2, the adhesive 6 is urged at least in regions, whereby the weldable element 4 is moved into abutment with the steel sheet 5. Subsequently, respective electrodes of a welding device are applied to the weldable element 4 and the steel sheet 5 and the weldable element 4 is welded to the steel sheet 5 by means of resistance spot welding using the welding device.

[0019] In order to keep corrosion particularly low between the aluminum sheet 2 and the weldable element 4 or the steel sheet 5, there is provision for the adhesive 6 to be introduced into the joint 7, whereby the joint 7 can be completely filled with the adhesive 6. Using the adhesive 6, consequently, air can be urged out of the joint 7. It is thereby possible to prevent air humidity from precipitating in the joint 7 or fluid from accumulating in the joint 7. As a result of the accumulation of fluid in the joint 7 being prevented, a current flow in the liquid can be prevented with the aluminum sheet 2 and/or the weldable element 4, whereby the risk of corrosion is kept particularly low.

[0020] In order to be able to ensure that the adhesive 6 flows into the joint 7, a reservoir 9 connected to the joint 7 is preserved at the side 8 of the aluminum sheet 2 facing the steel sheet 5. In this case, the reservoir 9 is in the form of an annular groove. In particular, the adhesive 6 which is located between the weldable element 4 and the steel sheet 5 can be urged into the reservoir 9. Subsequently, the adhesive 6 can flow out of the reservoir 9 into the joint 7 in order to completely fill the joint 7. The reservoir 9 is in this instance a recess of the aluminum sheet 2. The reservoir 9 is constructed to be open in the direction toward the steel sheet 5.

[0021] The weldable element 4 is in this case a press-in element. In this case, the weldable element 4 has a double cone form with tips directed counter to each other. The weldable element 4 can thereby be introduced in the aluminum sheet 2 in a positive-locking manner, whereby a particularly reliable connection is provided between the aluminum sheet 2 and the weldable element 4. The weldable element 4 can terminate flush with the aluminum sheet 2 at the side of the aluminum sheet 2 facing the steel sheet 5. Alternatively, the weldable element 4 can spring forward between the aluminum sheet 2 and the steel sheet 5 over the side 8 of the aluminum sheet 2 facing the steel sheet 5 at the height of an adhesive layer which is intended to be preserved. It is thereby possible to ensure that the adhesive layer between the steel sheet 5 and the aluminum sheet 2 is adjusted, wherein at the same time a direct planar abutment of the weldable element 4 against the steel sheet 5 is enabled.

[0022] In order to support an inflow of the adhesive 6 into the joint 7 and in this case to ensure a complete electrical insulation of the weldable element 4 with respect to the aluminum sheet 2, a vacuum suction device can be placed against an additional side 10 of the aluminum sheet 2 opposite the side 8 which faces the steel sheet 5. Using the vacuum suction device, the joint 7 can be acted on with a reduced pressure, whereby adhesive 6 stored in the reservoir 9 is drawn into the joint 7. Alternatively or additionally, by means of a temperature of the adhesive 6 being adjusted, the flow behavior thereof in the joint 7 can be influenced. One possibility is to heat the component assembly 1 in a heating apparatus, such as a heating apparatus of a cathode dip-coating apparatus. As a result of the heating of the component assembly 1, a viscosity of the adhesive 6 can be reduced, whereby the adhesive 6 flows particularly advantageously out of the reservoir 9 into the joint 7. Alternatively or additionally to heating the entire component assembly 1, at least adhesive 6 in the vicinity of the joint 7 can be heated by adjusting a temperature in the joint 7 during resistance welding, whereby the adhesive 6 flows into the joint 7 particularly advantageously. A temperature of an outer side, which delimits the joint 7, of the weldable element 4 can be adjusted via an adjustable current flow between the weldable element 4 and the steel sheet 5, whereby again the temperature of the joint 7 can be adjusted. In particular, a temperature which is intended to be adjusted in the joint 7 can be predetermined and the current flow can be selected in accordance with the predetermined temperature for the joint 7 during resistance welding, in which the predetermined temperature in the joint 7 results from thermal conduction in the weldable element 4. In order to be able to keep a welding temperature particularly low, the adhesive 6 may comprise adhesive substance proportions, the boiling temperature of which is below the temperature produced in the joint 7 during welding. During resistance welding, consequently, these adhesive substance proportions particularly evaporate out of the reservoir 9 into the joint 7 and can condense in the joint 7, whereby the joint is filled with the adhesive 6. Alternatively or additionally, a gelling agent and/or a propellant and/or magnetizable particles can further be added to the adhesive 6. The magnetizable particles bring about a flow of the adhesive 6 into the joint 7 in the event of a current flow between the steel sheet 5 and the weldable element 4 during the resistance welding. As a result of the current flow between the weldable element 4 and the steel sheet 5 during resistance welding, a magnetic field is produced at least in the joint 7. As a result of the magnetic field produced, the magnetizable particles of the adhesive 6 are orientated in the magnetic field, whereby the adhesive 6 is transported into the joint 7. The propellant may be, for example, a foam-forming agent which brings about a forward movement of the adhesive 6, particularly into the joint 7. Via the propellant, consequently, the adhesive 6 is urged out of the reservoir 9 into the joint 7. Using the gelling agent, the adhesive 6 can be gelled, whereby flow properties of the adhesive 6 can be adjusted. The adjusted flow properties by gelling the adhesive 6 can be selected in such a manner that the adhesive 6 flows into the joint 7 in a particularly simple and rapid manner. Using the adhesive 6, consequently, a contact zone, in this case the joint 7, between the aluminum sheet 2 and the weldable element 4 can be sealed.

[0023] The described component assembly 1 is based on recognition that in body construction there is the challenge of joining together aluminum sheets and steel sheets. In order to join the aluminum sheet 2 to the steel sheet 5, different joining methods can be used. In particular, the aluminum sheet 2 and the steel sheet 5 can be connected to each other via resistance element welding. If auxiliary means, in this instance the weldable element 4, are pressed in, a completely fluid-tight connection is scarcely possible without additional auxiliary agents between the weldable element 4 and the aluminum sheet 2. In order to secure the weldable element 4 to the aluminum sheet 2 so as to prevent corrosion, there is provision for the joint 7 to be completely filled with the adhesive 6. Using the adhesive 6, the aluminum sheet 2, the steel sheet 5 and the weldable element 4 can be protected from corrosion.

[0024] A problem which forms the basis of the corrosion is that, as a result of an electrochemical potential of aluminum and steel, a potential gradient is applied between the aluminum sheet 2 and steel sheet 5 which can result, with direct contact between the metal sheets and in the presence of an electrolyte, in corrosion effects. Similarly, air inclusions in cavities can result in corrosion effects if air humidity precipitates from included air. During the resistance element welding, in a first process step the weldable element 4 is pressed into the aluminum sheet 2, whereby a direct metal contact can occur between the weldable element 4 and the aluminum sheet 2 in the prior art. As a result of technical production inaccuracies, a contact zone of the weldable element 4 with the aluminum sheet 2 in the prior art cannot be formed to be completely smooth. In this case, air inclusions or capillaries may be anticipated.

[0025] In the component assembly 1 which is shown in the single FIGURE, initial effects of the adhesive 6 are selectively used in order to keep a risk of corrosion of the component assembly 1 particularly small. There is provision in the component assembly 1 for the opening 3 not to be completely filled with the weldable element 4, but instead for the reservoir 9 to be preserved, when the weldable element 4 is arranged in the opening 3 of the aluminum sheet 2. After application of the adhesive 6 between the steel sheet 5 and the aluminum sheet 2, the adhesive 6 is pressed, when the steel sheet 5 is pressed against the aluminum sheet 2, and flows into the preserved reservoir 9. Subsequently, the adhesive 6 is intended to be selectively brought into a contact zone between the weldable element 4 and the aluminum sheet 2. As a result of the vacuum suction device which is placed from an upper side, in this case the additional side 10, onto the aluminum sheet 2, can be combined with a set of welding tongs of a resistance welding device, can be placed flush around the weldable element 4 and can be acted on with suction, the adhesive 6 is drawn into the joint 7, which is a remaining air gap between the weldable element 4 and the aluminum sheet 2. In this manner, remaining cavities can be filled with the insulating adhesive 6 which further brings about a particularly high connection strength.

[0026] By selectively controlling the current load during the resistance spot welding, a temperature field in the joint 7 can be adjusted, which leads to the adhesive 6 in the reservoir 9 reaching a temperature, in particular a boiling temperature, which results in the adhesive 6 evaporating. This vapor with displaced adhesive particles can rise upward in the joint 7 in the manner of a chimney and close the joint 7 by means of the contained adhesive particles. By adding readily vaporizing, adhesive substance proportions in the adhesive 6, this selective vaporizing can be adjusted to temperature ranges which can be reached during resistance spot welding in the joint 7.

[0027] Alternatively or additionally, the magnetizable particles can be added to the adhesive 6. As a result of the alternating current field which is produced during resistance spot welding in the steel sheet 5 and the weldable element 4, an acting magnet is also produced in the joint 7. This magnetic field enables an adhesive proportion which is magnetized by means of the magnetizable particles to be pressed by means of an acting Lorentz force into the joint 7.

[0028] Alternatively or additionally, a temperature effect of a dryer oven acting as a heating apparatus of a cathode dip-coating device can be used in order to use the adhesive 6 for at least partially vaporizing and rising in the joint 7. Alternatively or additionally to adding magnetizable particles, it is possible to add propellant. This propellant leads to an increase in volume of the adhesive 6 when a predetermined temperature is adjusted and/or to the adhesive 6 flowing, whereby the adhesive 6 advances into the joint 7 by this propelling force and closes the joint in an insulating manner increasing the strength.

[0029] Effects of a diffusion can also be used, as a result of which the adhesive 6 diffuses in the joint 7 and closes it with increasing cooling. This diffusion effect can be supported by gelling the adhesive 6, whereby a capacity of the adhesive 6 for propulsion in comparison with the non-gelled adhesive is increased.

[0030] The aluminum sheet 2 may be at least a portion of an aluminum side frame of a motor vehicle. The connection of the aluminum sheet 2 to the steel sheet 5 can be reliably produced only via the resistance element welding, wherein an occurrence of a contact zone between the weldable element 4 and the aluminum sheet 2 can be sealed by the above-described effects. A particularly high connection strength can be achieved and a tendency toward corrosion can be kept particularly low, whereby a particularly advantageous failure behavior is achieved in a dynamic loading area.

[0031] Overall, the invention sets out a novel combination of at least one adhesive reservoir during resistance element welding for sealing and for increasing the strength.

LIST OF REFERENCE CHARACTERS:

[0032] 1 Component assembly [0033] 2 Aluminum sheet [0034] 3 Opening [0035] 4 Weldable element [0036] 5 Steel sheet [0037] 6 Adhesive [0038] 7 Joint [0039] 8 Side [0040] 9 Reservoir [0041] 10 Additional side