METHOD FOR PRODUCING A CONNECTION BETWEEN A FIRST PLASTIC COMPONENT AND A SECOND PLASTIC COMPONENT AND COMPONENT CONNECTION PRODUCED THEREBY

Abstract

The invention relates to a method for producing a connection between a first plastic component and a second plastic component, wherein at least one of the two components is produced by plastics injection moulding, wherein at least one fastening region is provided on the at least one component and is moulded with a surface structure of grooves having a small spacing, and wherein the components are connected to one another by an ultrasonic welding method in the fastening region.

Claims

1. A method for producing a connection between a first plastic component and a second plastic component, comprising: producing at least one of the two components by plastics injection moulding; forming at least one fastening region on the at least one component that is moulded with a surface structure of grooves having a small spacing; and connecting the components to one another by ultrasonic welding in the fastening region, wherein the grooves being produced in the fastening region of the at least one component with a groove apex to groove apex spacing of from 0.1 to 2 mm.

2. The method according to claim 1, wherein the grooves are produced in the fastening region of the at least one component so as to be at least partially parallel to one another.

3. The method according to claim 1, wherein the grooves are produced in the fastening region of the at least one component with a depth between the groove apex and a groove base of from 0.1 to 2 mm.

4. The method according to claim 1, wherein the grooves form squares, rectangles or hexagons that are produced with an extent of from 0.2 to 3 mm and a depth of from 0.1 to 1.5 mm.

5. The method according to claim 1, wherein the fastening region is structured with pyramids or cones.

6. The method according to claim 1, wherein energy for the welding is introduced into the plastic components via at least one pin of a sonotrode, the two components being spot-welded to one another step-by-step.

7. The method according to claim 6, characterized in that the next respective welding step is carried out in a region which has already been stressed by the previous step of the welding and relaxed again.

8. The method according to claim 1, characterized in that the components are bumpers and holders for sensors, reinforcing parts and other parts having a relatively thin wall thickness.

9. A component connection produced between two components which are connected by the method according to claim 1.

Description

DRAWINGS

[0028] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0029] FIG. 1 shows a schematic representation of a bumper at the front.

[0030] FIG. 2 shows a sonotrode in the prior art.

[0031] FIG. 3 shows an exemplary welding path.

[0032] FIG. 4. shows a surface structure.

[0033] FIGS. 5a, 5b and 5c each show a plan view of surfaces of a component.

DESCRIPTION OF THE INVENTION

[0034] FIG. 1 shows an exemplary embodiment of an exemplary bumper 1, such as is used on the front of a vehicle. The bumper 1 in this case constitutes a first plastic component 31. The latter may however also be a sill, a boot door, a wheel arch trim or another plastic part in the exterior region of the vehicle.

[0035] On a side 1b of the bumper 1 facing towards the vehicle, holders 2 for various sensors, for example, are fastened. Reinforcing parts, spoilers, etc, may however also be connected as a second component 32 to the first component 31. The holder 2 represented by way of example in this case has an annular bearing surface 3 and a cylindrical receptacle 4. A sensor is inserted into the receptacle 4 and is retained by means of the connectors 5 fitted on the receptacle 4 using a clip connection or a bayonet connection. An outwardly facing surface 1a of the bumper 1 must not show visible traces of the holder or holders 2, and must impart a perfect paint appearance.

[0036] The bearing surface 3 of the holder 2 may, in this case, naturally also be configured to be square or rectangular, as well as asymmetrical, in order to ensure accurate positioning definition of the holder 2 on the bumper 1. A possible welding path 10 is indicated as a circular path.

[0037] On the inner side 1b of the bumper 1, a fastening region 20 for the holder 2 is shown, which in this example is selected to be rectangular.

[0038] A cross section through the fastening region 20 of the bumper 1 is shown by FIG. 4. The surface of the bumper 1 is formed with a groove structure, which is also shown in plan view in FIG. 5a. The grooves 21 are applied with their depth only on the surface of the bumper 1, which has a substantially larger thickness of up to 15 mm.

[0039] The grooves have a spacing of less than one millimetre, this being a spacing of 0.7 mm from one groove apex 21a to the next groove apex 21a in the exemplary embodiment. The depth of the grooves from the groove apex 21a to the groove base 21b is for example 0.6 mm. The range for the spacing of the groove apexes is set between 0.1 and 2 mm, and the groove depth at 0.1-2 mm. In this range, an optimal strength is imparted to the desired connection.

[0040] The grooves 21, as shown in FIG. 5a, are arranged linearly and parallel to one another in one embodiment. FIG. 5b shows an arrangement in a chequerboard pattern, in which the groove apexes 21a form squares or rectangles or a hexagonal structure. In this case, however, the small spacing between the groove apexes 21a and the depth from the groove base 21b are preserved.

[0041] One exemplary embodiment uses 1×1 mm large squares having a depth of 0.2 mm and a spacing of 1.5 mm of the groove apexes from one another. The optimal range is a configuration of 0.2 to 3 mm spacings and a depth of from 0.2 to 3 mm.

[0042] FIG. 5c represents a surface structure which forms small pyramids based on a square or rectangle. A cone structure based on circles and ellipses is also possible. The height of the pyramids or cones is in this case between 0.1 and 2 mm, and the spacings are from 0.1 to 2 mm. The cones may also be configured as truncated cones.

[0043] During the production of the connection between the bumper 1 and the holder 2, that is to say a first plastic component 31 and a second plastic component 32, the first and second plastic components are produced by plastics injection moulding. The first component 31 or the second component 32, or both components, have one or more fastening regions 20. These are produced with the overall shape of the components during the plastics injection moulding.

[0044] The materials used in this case are for example PP, PP with talc, PP with glass fibres, ABS, PC with ABS and ASA.

[0045] In the next step, the components 31, 32 are connected to one another with a form-fit, the fastening regions 20 being used as bonding surfaces.

[0046] Ultrasonic welding methods may be used as the welding methods. For example, the welding method known from DE 10 2020 200 184 A1 is used.

[0047] The method uses ultrasonic welding employing a sonotrode 6, which is represented by way of example in FIG. 2. The sonotrode 6 in this exemplary embodiment has two pins 7. By means of such a sonotrode 6, the holder 2 is spot-welded to the bumper 1 at the two pins 7.

[0048] The welding process is in this case carried out step-by-step by means of moving the sonotrode 6 along the bearing surface 3 of the holder 2, which bears on the fastening region 20. In the example of FIG. 1, the sonotrode moves along a circular line in the region of the annular bearing surface 3.

[0049] FIG. 3 represents a linear welding path. The welding spots 11 are placed pairwise by employing the sonotrode with two pins. After the welding step S1, the welding step S2 is carried out, etc. A region of the energy influence 9 is denoted for the welding step S1, and likewise in the welding step S4.

[0050] After the first step of the welding, for example S1, the next step S2 is carried out in a region 9 of the plastic element which has already been exposed to specific loading by the first welding step S1 and is again in the relaxed state. Because of the surface structuring with grooves 21, the surface of the first and/or second component 31, 32 is increased so that the melting of the structure takes place better and more efficiently.

[0051] This means that less energy, stress and thermal influence need to be applied for the second welding step S2 than for S1, since the material has not yet fully cooled and resolidified. Because of the stepwise welding, less energy is introduced overall into the components to be welded, yet the welded connection is very strong. The strength of the connection is increased by from 9 to 13% compared with connection between components without a surface structure.

[0052] There must in this case be a certain time interval between the individual welding steps S1, S2, in order to give the material the opportunity to relax.