Overlap adhesive joint

TECHNICAL FIELD

The present invention relates to an overlap adhesive _. joint including a first and a second plate part, which

-, overlap each other, and an intermediate adhesive layer, the joint preferably being a joggled joint.

Although the term "plate part" is to be taken as having 10 a wide sense in the present context, the invention is prima¬ rily directed to thin sheet metal parts and particularly vehicle body panel parts. The invention will therefore be described hereinafter in connection with vehicle plane joints, particularly joints for the rebuilding of door edges, 15 wing edges, bootlid edges and the like.

TECHNICAL BACKGROUND

There is a great amount of rust and damage repairs to vehicle bodies. The kind of activity envisaged here is, for 20 example, the repair of panel edges that have rusted away or the repair of collision and similar damage, in which so-called economy panel parts are utilised.

Up to now, these economy panel parts have usually been put in place with the aid of welding. Welding requires 25 special equipment, extensive dismantling of combustible material and causes difficulties with respect to protection against later rust attack.

Economy panel parts have also been put in place utili¬ sing riveted and/or screwed joints, which, however, is a 30 complicated technique and from many aspects gives poorer joint properties.

More recently it has been proposed that body panel parts should be joined together using an adhesive joint. Adhesive joints have a series of advantages: good '* ^■ 35 stiffness and dynamic strength; they dampen vibrations; there

V is no distortion due to heating, since curing or setting may take place at room temperature; different kinds of plates can

be joined together; thin plates can be joined without diffi¬ culty.

However, adhesive joints are burdened with certain problems such as: poor peeling strength and also poor shear strength in certain cases; the plates must be carefully secu- red in relation to each other during the setting time; the plates must be very carefully fitted to each other to avoid, inter alia, injurious stresses; there may be a certain creep in the joint after some time; the visco-elastic properties of the adhesive may have drawbacks.

OBJECT OF THE INVENTION

The object of the present invention is to provide an improved overlap adhesive joint of the kind mentioned in the introduction, whereby the above-mentioned problems are miti¬ gated to a substantial extent.

SUMMARY OF THE INVENTION

In accordance with the invention, this object is achieved by an overlap adhesive joint having the distinguishing features disclosed in the accompanying claims.

The overlap adhesive joint in accordance with the in¬ vention is thus essentially distinguished in that the plate parts also are mutually, mechanically locked, in that projec- tionβ projecting from one plate part extend through apertures made in the second plate part, so that peeling strength and shear strength are improved. The projections preferably extend in under the second plate part and advantageously such that the projections are in engagement with the underside of said second plate part.

It will be understood that the dimensions of the pro¬ jections and the apertures should be such that the actual, mechanical joining of the plate parts will be simple, but after this the plate parts will be, in principle, unmovably locked to each other in predetermined mutual fixation corresponding to their desired positions in the joint.

Advantageously, the projections are tongues stamped or bent out. Suitably, they have their extension substantially at right angles to the longitudinal direction of the joint and to advantage are achieved by cutting or slitting ^ 5 inwardly from the joint edge of the associated plate part. Advantageously, the projections have a hook configuration. As will be easily understood, the apertures coacting with the projections are easily provided in an optional manner.. Advantageously, the apertures can have a width 10 corresponding to the width of the projections passing through them. The apertures may have round or square or other suit¬ able configuration, as long as the desired lock against mutual movement between the plate parts in the shearing plane is obtained. The desired lock against peeling is ensured, as 15 will be understood, primarily by the projections locking against the underside of the plate part having the apertures. According to a preferred embodiment, the apertures have been achieved by stamping or bending out tongues or the like on the underside of the plate part provided with the aper- 20 tures, these aperture tongues being adapted to coact with the projections taken through the apertures formed to give a re¬ silient compressing effect.

The adhesive utilised is suitably applied so that an adhesive joint is also obtained between the underside of the 25 holed plate part and adjacent projection parts, as well as round the projections in the apertures. It is also suitable for the adhesive to fill up the cavities formed in the plate part having projections in conjunction with stamping or bending out the tongue-like projections. Such shaping of the 30 projections can easily be provided with the aid of tongs for¬ med for the purpose.

As will be understood, the mechanical lock in accordan¬ ce with the invention means that peeling or shearing of the » joint is mechanically inhibited. Furthermore, mechanical fi- - ^' 35 xation and location are obtained, which means that previously utilised special means to that effect (such as spot welds, tongs etc) can be dispensed with. All creeping and other un-

favourable effects due to the viscoelastic properties of the adhesive are prevented. A joint is thus obtained which has generally improved strength properties simultaneously as the achievement of the joint can be simplified, particularly with regard exact fitting of the plate parts in the joint to each other and locking in such a position.

The invention will how be described in more detail with the aid of embodiments and with reference to the accompanying drawing.

BRIEF DESCRIPTION OF DRAWING

Figure 1 is a schematic partial plan view illustrating an overlap adhesive joint in accordance with the present in¬ vention. Figure 2 is a schematic sectional view taken along the line 11—11 in figure 1.

Figure 3 is a schematic sectional view as in figure 2, the adhesive included in the joint being excluded for the sake of clarity. Figure 4 is a schematic sectional view of the same kind as in figure 3, illustrating an alternative embodiment.

DESCRIPTION OF EMBODIMENTS

Figures 1-3 illustrate joining, in accordance with the invention, two plate parts 1 and 3, which in the illustrated embodiment are substantially flat at the joint and which may be part of a car door, for example. Thus, the upper case panel part 1 is the lower part of the outer door panel, while the panel part 3 i a so-called economy panel part for re- placing a rusted door pannel lower edge. The joint is a joggled joint, where the lower edge region of the panel part 1 is pressed down to form a continuous flat flange 5, against which the upper edge part 7 of the panel part 3 is adhered with the aid of a thin adhesive layer 9 in the form of a brushed-on completely covering film. The joggling, which can be achieved in a manner known per se using a joggling tool, corresponds to the thickness of the panel part 3 plus the

thickness of the adhesive layer, so that the outside of the panel part 3 is flush with the outside of the panel part 1. The width of the flange 5 is about 20 mm. The thickness of the adhesive layer 9 is typically 50 to 200 μm. The adhesive is a two-component polyurethane adhesive setting already at about 20°C. The adhesive also fills out the gap 11 between the edge 13 of the panel part 3 and the step 15 between the flange 5 of the panel part 1 and the remainder of the panel part. Panel part thickness is typically about 1 mm. The panel parts 1 and 3 are also mechanically locked to each other and posi ionally fixed at regular intervals along the joint, more specifically in connection with the edge 13 of the edge part 7. At each locking location there is ob¬ tained mechanical locking by the coaction between a tongue 17, parted and bent downwards from the panel edge part 7 and a corresponding aperture 19 in the flange 5. The substantial¬ ly uniformly wide tongue 17 is defined by two cuts extending from the panel edge 13 inwards on the edge portion 7 and thus leaves a substantially rectangular opening 21 in the edge portion 7. The tongue has a generally hooked configuration as illustrated and thus includes a first part extending general¬ ly transversely away from the underside of the edge portion 7 and passing through the aperture 19, and a second part ex¬ tending generally along and below the flange 5. However, said parts have respective inclinations such that the projection

17 may easily be passed through the associated aperture 19 by the edge part 7 and flange 5 being approached to each other at a given angle while inserting the projection 17 in the aperture 19, subsequent to which the edge part 7 is swung downwards to its position along the flange 5, the mechanical lock thus being ensured.

The aperture 19 is rectangular and has a width corresponding to the width of the projection 17, whereby po¬ sitioning and locking with relation to lateral displacement <i.e. in the direction of the joint) is ensured. The inner edge of the aperture 19 (i.e. closest to the step 15) has a position such that the edge gives a well-defined location to

S

the edge 13 of the panel part 7 when this aperture edge is in contact with the projection 17 in the locked position.

The length of the aperture 19 (i.e. the extension at right angles to the direction of the joint) is selected such 5 that the projection 17 may be inserted with sufficient ease as well as suitably such that withdrawal of the edge portion 7 from the locked position in figures 2 and 3 (i.e. pulling the panel parts 5 and 7 apart along themselves) is prevented. The. panel parts 5 and 7 will thus be unmovably secured rela- 0 t±v-€- each other when the position illustrated in figures 2 and. 3 has been obtained.

As will be seen from figure 2, the adhesive joint it¬ self includes the parts of the projection 17 in the aperture 19 and on the remote side of the flange 5 as well as the 5 opening 21. There is thus obtained a reinforced joint which is substantially smooth on its upper side, and which is secured against both peeling and shearing.

An alternative embodiment of an overlap adhesive joint in accordance with the invention is schematically illustrated 0 in figure 4. This embodiment differs from the one according to figures 1-3 in that the respective aperture 19 is provided by cutting and bending out a tongue 23 in the flange 5. The tongue 23 is generally directed in the same direction as the projection 17 and is adapted yieldingly to press against the 5 projection 17 so that the parts 5 and 7 are pressed together by the part 7 striving to be "swung in" towards the part 5. It will be understood that the tongue 23 can also advan¬ tageously define the rear edge of the aperture 19 so that the previously mentioned withdrawal of the part 7 is prevented. _3. The invention is naturally not restricted to the illustrated and described embodiments, and alterations and modifications are possible within the scope of the following claims .