DE102020108759B4 - Process for joining at least two components - Google Patents

Abstract

Method for joining at least two components (1, 2), with a setting process in which an auxiliary joining element (3) is driven into a first component (1), so that an element head (7) of the auxiliary joining element (3) has an element head overhang projects beyond a component surface of the first component (1), with a delivery step in which the second component (2) is brought into contact with an upper side of the element head (7), so that between the first component (1) and the second component (2 ) a gap (11) remains, and with a resistance spot welding step in which the second component (2) is welded to the element head (7) of the auxiliary joining element (3), an insulating element (15) being provided which, after the setting process, replaces the element head (7) of the auxiliary joining element (3) radially on the outside, and with the insulating element (15) acting as a component support which ensures direct electrical contact between the two components (1, 2) prevented as a result of a component tilting movement, characterized in that the insulating element (15) is clamped after the setting process between the element head (7) and the component surface of the first component (1) to prevent loss.

Description

The invention relates to a method for joining at least two components according to the preamble of claim 1.

In automobile construction, the vehicle body can be manufactured in a mixed construction, for example in which a press-hardened steel component is connected to an aluminum structure. From the DE 102014 011 599 A1 An exemplary joining method is known in which an auxiliary joining element (i.e. a rivet element) is first driven into a first component (i.e. an aluminum structure) in a setting process, so that an element head of the auxiliary joining element protrudes with an element head overhang from a component surface of the first component . In a subsequent delivery step, the second component (e.g. a press-hardened steel component) is brought into contact with an upper side of the element head of the auxiliary joining element, so that a gap remains between the first component and the second component, which approximately corresponds to the overhang of the element head. This is followed by a resistance spot welding step, in which the second component (ie the press-hardened steel component) is welded to the element head of the auxiliary joining element.

The resistance spot welding step can be done on both sides with spot welding guns with the welding electrodes on opposite sides of the assembly in alignment. As an alternative to this, the resistance spot welding step can optionally also be carried out on one side, in which case the two welding electrodes are arranged on the same side of the component arrangement to be connected. Especially when implementing a resistance spot welding step carried out on one side, the two welding electrodes of the welding tongs are not aligned centrally with one another, but rather arranged side by side with a lateral offset. In the resistance spot welding step, the component arrangement can therefore be subjected to a tilting moment, so that under certain circumstances the two components can come into direct electrical contact as a result of a component tilting movement. In this case, there is a shunt between the two components (i.e. the aluminum component and the steel structure). As a result, there is no longer enough thermal energy available for the formation of a weld nugget at the intended joining point, which results in a reduced weld joint strength or the weld joint does not come about at all.

From the U.S. 2017/0057005 A1 a method for joining two components by means of an auxiliary joining element is known. From the DE 10 2018 003 083 A1 a weld rivet joint is known. From the U.S. 2018/0272417 A1 and from the U.S. 2010/0173123 A1 other joining methods are known.

From the DE 10 2014 115 370 A1 an assembly unit with an assembly part and a welding element as well as a generic method for producing the assembly unit are known. The US 2020/0147671 A1 discloses a method of making various material fasteners.

The object of the invention is to provide a method for joining at least two components in which an operationally reliable component connection is made possible in a simple manner in terms of process and production technology.

The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the dependent claims.

The invention relates to a method in which an auxiliary joining element is initially driven into a first component in a setting process, so that an element head of the auxiliary joining element projects beyond a component surface of the first component with an element head overhang. In addition, the auxiliary joining element is driven into the first component while maintaining a residual bottom thickness in the first component and while spreading the auxiliary joining element. This is followed by a resistance spot welding step, in which the second component is welded to the element head of the auxiliary joining element. According to claim 1, an additional insulating element is provided which, after the setting process, surrounds the element head of the auxiliary joining element radially on the outside. The insulating element acts as a component support, in which an excessively large misalignment of the two components, for example as a result of a component tilting movement, is prevented in the infeed step and in the resistance spot welding step. In this way, the insulating element prevents direct electrical contact between the two components.

By using an insulator in the immediate vicinity of the auxiliary joining element, designed as an insulating disc, an unwanted flow of current between the components can be prevented and thus conducted to the intended point. A welding process implemented on one side enables the improvement or redesign of future body concepts with regard to the joining sequence or optimization of the vehicle weight, for example by eliminating so-called steel adapters. The welding process can be significantly improved with the new idea. In a technical implementation, by means of a preferential wisely perforated plastic disk, an isolating surface or gap between the two components for one-sided/indirect resistance spot welding with rivet element is deliberately created in order to prevent a shunt through, for example, sheet metal trimmed edges, especially with narrow flanges. Furthermore, the components are stabilized relative to one another (that is, tilting is prevented).

The plastic disc is used in combination with semi-hollow rivet-like auxiliary parts. The plastic disc also prevents the aluminum material from spattering, which is an essential quality feature.

Other element geometries that only form a head-like geometry during the setting process, such as a clinch rivet, are included. This can also be used for other elements such as the WES element or solid punch rivet.

The technical implementation is carried out, for example, via a swivel unit that brings the pane into position immediately before the element is set and holds it until the hold-down device has touched it.

The disc should preferably have the following technical specifications: maximum material thickness of 0.5 mm; temperature resistant up to 600°C; Outer diameter of the insulating disk is at least twice the diameter of the head, but no more than a flange width of 18 mm; Inner diameter of insulating washer depends on element size; Insulator material can be nylon, PTFE, vinyl or the like.

The insulating disk can be used for one-sided as well as two-sided rivet spot welding. It also makes no difference whether it is a single- or multi-shear joint and whether adhesive is used in one of the joint planes. Furthermore, the disc can be pre-drilled or designed as a full disc, i.e. without a pre-drilled hole. With the latter, the pane is punched through when the element is set. After the setting process, the insulating disc is clamped between the underside of the head edge of the element head and the component surface of the first component, in particular the aluminum sheet part.

The clamping of the washer between the rivet head and the aluminum component can be created in three ways: In a first version, the washer can already be applied captively during the manufacturing process of the rivet element. This means a high degree of friction or tension between the disc and the element, since the entire (transport) route, from filling to setting the element, it must be ensured that the disc does not fall off.

In a second variant, the setting process can be decoupled and divided into two partial steps. First, the disc is placed below and coaxially under the hold-down device using a separate feed and gripping unit and held in position until it fixes the disc, then the spindle presses the element into the aluminum component and the disc and element head are clamped.

In a third variant, a disk-like sticker or a correspondingly perforated adhesive tape or foil can be applied to the individual part in an upstream process step. The element is then set in a further process step.

A fourth variant can take place using a running process belt arranged below the hold-down device, which is pre-perforated or equipped with the discs. Before it is set, the disc is pressed onto the component by the hold-down device and punched out. After that or during this process, the element is set in the usual way.

After setting the element including the disc, the welding process takes place. The welding electrode is preferably positioned on one side of the matrix formation (aluminum side). The disc now prevents tilting, or in the event of a slight tilting, the two joining partners (steel and aluminum) do not touch each other due to the disc, but only the intended joining point (element head).

In order to carry out the setting process, a setting unit is provided in common practice, which has a hold-down device, a setting punch and a die. In the setting process, the hold-down device presses the first component (i.e. aluminum component) against the die with a hold-down force. The setting die then drives a pre-positioned auxiliary joining element into the first component with a setting force.

Aspects of the invention are highlighted in detail below: According to the invention, the insulating element is clamped after the setting process between the element head and the component surface of the first component to prevent loss. In addition, with regard to its support function, the insulating element can be designed as a substantially structurally stable hard plastic component. This is particularly heat-resistant, even in cons Spot welding step to be able to fulfill the support function. So that the insulating element does not act as an interfering contour in the lining step and in the resistance spot welding step, it is preferred if the insulating element has a material thickness that is smaller than the overhang of the element head. In this way, a direct electrical contact between the upper side of the element head and the second component is ensured during the delivery step.

In a preferred embodiment, the gap between the two components can be filled with adhesive. The adhesive is applied, for example, after the setting process. Due to the defined element head overhang of the auxiliary joining element, the adhesive can be locally displaced during the infeed step and distributed in the gap. In contrast to the insulating element, the adhesive is not formed from a hard component, but rather is made from a pasty, non-heat-resistant soft component (starting component), at least in the delivery step. For this reason, the adhesive cannot fulfill a supporting function within the meaning of the insulating element according to the invention, either in the delivery step or in the resistance spot welding step.

The insulating element can be positioned in the joint in different variants: According to a first variant, the insulating element can be captively connected to the not yet formed (i.e. not set) auxiliary joining element in a pre-assembly step preceding the setting process. The connection takes place in particular on the underside of the element head of the auxiliary joining element.

In a further embodiment variant, the insulating element can be positioned below the hold-down device on the first component before the setting process is carried out (that is to say by means of a separate feed and gripper unit). This is followed by the setting process, in which the auxiliary joining element is driven into the first component. This takes place with the insulating element being jammed between the element head and the component surface.

In a further embodiment variant, the insulating element can be glued captively to the component surface of the first component (i.e. aluminum component) at a predefined desired joint point in an assembly step preceding the setting process. This is followed by the setting process, in which the glued-on insulating element is clamped between the element head of the auxiliary joining element and the component surface.

In a fourth embodiment variant, the setting unit can be assigned a running process belt, which is arranged below the hold-down device and is equipped with insulating elements. For example, the insulating elements can be integrated in the strip material of the process strip from the same material and/or in one piece and can be detached from the strip material at predetermined breaking points. In this case, before the setting process is carried out, the hold-down device presses one of the insulating elements onto the first component (for example by being punched out of the process strip). The setting process is then carried out, in which the insulating element is clamped between the element head of the auxiliary joining element and the component surface of the first component.

Exemplary embodiments of the invention are described below with reference to the accompanying figures.

• 1 und 2 in unterschiedlichen Teilschnittdarstellungen eine fertiggestellte Bauteilverbindung;
• 3 bis 5 jeweils Ansichten, anhand derer Prozessschritte zur Herstellung der in der 1 gezeigten Bauteilverbindung veranschaulicht sind; und
• 6 bis 8 jeweils Ansichten, die Ausführungsvarianten der Erfindung andeuten.

Show it:

• 1 and 2 a completed component connection in different partial sectional views;
• 3 until 5 each views, based on which process steps for the production of in the 1 component connection shown are illustrated; and
• 6 until 8th each views indicating variants of embodiment of the invention.

In the 1 a finished component connection is shown, in which an aluminum sheet part 1 is connected to a press-hardened sheet steel part 2 . The sheet steel part 2 is, for example, part of a rocker panel of a vehicle body. The two sheet metal parts 1 , 2 are connected to one another via an auxiliary joining element 3 . The joining aid element 3 is according to 3 (Shows the auxiliary joining element 3 in the undeformed manufacturing state) in the manner of a semi-hollow punch rivet, with an element shaft 5 and an element head 7. In FIG 1 the auxiliary joining element 3 is driven into the aluminum sheet part 1 while spreading its element shaft 5 and maintaining a residual base r. The auxiliary joining element 3 is at its element head 7 via a weld nugget 9 in a welded connection with the sheet steel part 2. According to FIG 1 the auxiliary joining element 3 projects beyond the component surface of the aluminum sheet part 1 with an element head overhang, as a result of which the two sheet metal parts 1, 2 are spaced apart from one another by a gap 11. In the 2 the gap 11 is partially filled with an adhesive 13.

How from the 2 As can further be seen, a disk-shaped insulating element 15 (hereinafter insulating disk) is clamped between the underside of the head edge of the element head 7 and the component surface of the aluminum sheet part 1 . The ring-shaped insulating disc 15 surrounds the element head 7 and has an outer diameter d _l which is a technical implementation can be about twice as large as the head diameter d _K of the element head 7. The material thickness m of the insulating disk 15 is in the 2 slightly smaller than the gap dimension of the gap 11. The insulating disc 15 is made of a heat-resistant plastic hard component, for example nylon, PTFE, vinyl, or the like.

The following is based on the 3 until 5 a process chain for the production of the 1 or 2 shown component connection described: Accordingly, in the 3 a setting unit is provided, which has a hold-down device 17, a setting punch 19 and a die 21. The aluminum sheet part 1 is first placed on the die 21 . The insulating pane 15 is positioned on the upper component surface of the aluminum sheet part 1 by means of a separate feed and gripper unit (not shown). The insulating disk 15 is in the 3 arranged below the hold-down device 17 at a predefined desired joint point S on the aluminum sheet part 1 . The insulating disk 15 is in the 3 already pre-punched. The setting process then starts, in which the hold-down device 17 presses the aluminum sheet part 1 with a hold-down force F _N against the die 21 with the insulating disk 15 interposed. The setting die 19 then drives the auxiliary joining element 3, which is pre-positioned in the hold-down device 17, with a setting force Fs into the aluminum sheet part 1, with the insulating washer 15 being securely clamped between the top edge of the auxiliary joining element 3 and the component surface of the aluminum sheet part 1.

After the setting process, there is a delivery step ( 4 ), in which the sheet steel part 2 is positioned on top of the element head 7 of the auxiliary joining element 3 .

The following resistance spot welding step ( 5 ) is carried out on one side, namely with welding electrodes 23, 25 of a spot welding gun, not shown, which are positioned with a lateral offset on the same side of the component connection. The welding electrode 23 is in electrical contact with a closed matrix formation 14 (or residual base r) of the aluminum component 1 at the specified joint S, while the welding electrode 25 is pressed laterally offset against the component surface of the sheet steel part 2 .

The following are based on the 6 until 8th different variants for pre-assembly of the insulating element 15 described: Accordingly, according to the 6 before the setting process is carried out, a pre-assembly step takes place, in which the insulating element 15 is captively connected to the still undeformed auxiliary joining element 3 . An example is in the 6 the insulating element 15 is glued to the underside of the edge of the element head of the auxiliary joining element 3 .

In the 7 In an assembly step preceding the setting process, the insulating element 15 is glued captively to the component surface of the aluminum sheet part 1 via an adhesive layer 27 at a predefined desired joint point S. For example, a disk-like sticker or a correspondingly perforated adhesive tape and/or foil can be applied to the aluminum sheet part 1 . The setting process then takes place, with the insulating element 15 being clamped between the edge of the element head and the component surface of the aluminum sheet part 1.

According to the 8th the setting unit also has a running process belt 29 arranged below the hold-down device 17 . The process band is fitted with a row of insulating elements 15 which, for example, are of the same material and are integrated directly in the band material of the process band 29 in one piece. Each of the insulating elements 15 can be detached from the strip material at predetermined breaking points 31 . Before the setting process, the hold-down device 17 punches one of the insulating elements 15 out of the process strip 29 and presses it against the component surface of the aluminum sheet part 1. The setting process is then carried out, with the stamped-out insulating element 15 being clamped between the element head edge of the auxiliary joining element 3 and the Component surface of the aluminum sheet part 1.

reference list

1

first component

2

second component

3

joining aid element

5

elementary

7

element header

9

weld nugget

11

gap

13

adhesive

14

die forming

15

insulating element

17

hold-down

19

setting stamp

21

die

23, 25

welding electrodes

27

adhesive layer

29

process belt

31

predetermined breaking point

H

Element Head Overhang

dI

Insulator diameter

dK

head diameter

FS

setting force

FN

hold down force

m

Material thickness of the insulating element

S

target joint

right

rest floor

Claims (8)

Method for joining at least two components (1, 2), with a setting process in which an auxiliary joining element (3) is driven into a first component (1), so that an element head (7) of the auxiliary joining element (3) has an element head overhang projects beyond a component surface of the first component (1), with a delivery step in which the second component (2) is brought into contact with an upper side of the element head (7), so that between the first component (1) and the second component (2 ) a gap (11) remains, and with a resistance spot welding step in which the second component (2) is welded to the element head (7) of the auxiliary joining element (3), an insulating element (15) being provided which, after the setting process, replaces the element head (7) of the auxiliary joining element (3) radially on the outside, and with the insulating element (15) acting as a component support which ensures direct electrical contact between the two components (1, 2) prevented as a result of a component tilting movement, characterized in that the insulating element (15) is clamped after the setting process between the element head (7) and the component surface of the first component (1) to prevent loss. procedure after claim 1 , characterized in that the insulating element (15) is designed as a hard plastic component with regard to its supporting function, and in that the hard plastic component is heat-resistant in order to also fulfill the supporting function in the resistance welding step, and/or that the insulating element (15) has a material thickness (m) that is smaller than the projection of the element head, in order to ensure electrical contact between the upper side of the element head (7) and the second component (2) during the delivery step. Procedure according to one of Claims 1 or 2 , characterized in that the gap (11) between the two components (1, 2) is filled with adhesive (13), and that the adhesive (13), in contrast to the insulating element (15), does not consist of a hard component but of a pasty one , Not heat-resistant soft component is made, so that the adhesive (13) are in the delivery step and in the resistance spot welding step without a support function. Method according to one of the preceding claims, characterized in that the insulating element (15) is captively connected to the still undeformed auxiliary joining element (3) in a pre-assembly step preceding the setting process, specifically on the underside of the element head (7) of the auxiliary joining element (3). Method according to one of the preceding claims, characterized in that a setting unit is provided for carrying out the setting process, which has a hold-down device (17), a setting punch (19) and a die (21), and that in the setting process the hold-down device (17) with a hold-down force (F _N ) presses the first component (1) against the die (21) and the setting punch (19) drives a pre-positioned auxiliary joining element (3) into the first component (1) with a setting force (Fs), and that the insulating element (15) is positioned below the hold-down device (17) on the first component (1) before the setting process is carried out, and that the setting process then takes place, in which the auxiliary joining element (3) is driven into the first component (1), specifically under Clamping of the insulating element (15) between the element head (7) and the component surface. Procedure according to one of Claims 1 until 3 , characterized in that the insulating element (15) is glued captively to the component surface of the first sheet metal part (1) at a predefined desired joint (S) in a pre-assembly step preceding the setting process, and in that the setting process is carried out with the insulating element (15) being clamped between the element head (7) of the auxiliary joining element (3) and the component surface of the first component (1). procedure after claim 4 , characterized in that the setting unit has a running process belt (29) which is arranged below the hold-down device and is equipped with insulating elements (15), and in that the insulating elements (15) are integrated in the belt material of the process belt (29) from the same material and/or in one piece and /or can be detached from the strip material at predetermined breaking points (31), and that before the setting process, the hold-down device (17) presses one of the insulating elements (15) onto the first component (1) and punches it out of the process strip (29), and that the setting process then follows with the intermediate clamping of the insulating element (15) between the element head (7) and the component surface of the first component (1). Method according to one of the preceding claims, characterized in that in the setting process the auxiliary joining element (3) is driven into the first component (1) while spreading and maintaining a residual base (r) or a closed matrix formation (14), and/or that the Resistance spot welding step takes place with welding electrodes (23, 25) arranged on one side, namely with a first welding electrode (23) which is in electrical contact with the matrix formation (14) of the first component (1) and a second welding electrode (25) which is in electrical contact with the second component (2).

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