METHOD FOR THE ULTRASONIC WELDING OF TWO PLASTIC COMPONENTS, AND PLASTIC COMPONENT PRODUCED THEREBY

Abstract

The invention relates to a method for the ultrasonic welding of two plastic components using a sonotrode, wherein the energy for the welding is introduced into the plastic components via at least one or more pins of the sonotrode, wherein the two plastic components are welded to one another step by step, wherein the respectively subsequent step of the welding is carried out in a region which has already been loaded and relieved of tension as a result of the preceding step of the welding.

Claims

1. A method for the ultrasonic welding of two plastic components using a sonotrode, wherein the energy for the welding is introduced into the plastic components via at least one pin of the sonotrode, wherein the two plastic components being spot-welded to one another step by step, wherein the respectively subsequent step of the welding is carried out in a region which has already been loaded and relieved of tension as a result of the preceding step of the welding.

2. The method according to claim 1, wherein the individual steps of the welding are performed spatially close to one another along a weld path.

3. The method according to claim 1, wherein the individual steps of the welding follow one another at a time interval which makes it possible to relieve the material of the plastic components of tension in the region of a weld.

4. The method according to claim 1, wherein the sonotrode is guided along the weld path.

5. The method according to claim 1, wherein the weld path extends linearly, circularly, or such that it follows any desired contour.

6. The method according to claim 1, wherein the pins of the sonotrode are placed flat, with a tip or with another specific contour on the plastic components to be welded.

7. The method according to claim 1, wherein the plastic components are bumpers and mounts for sensors, reinforcing parts and other parts with a relatively thin wall thickness.

8. Plastic components bonded in accordance with the method according to claim 1.

Description

DRAWINGS

[0026] 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.

[0027] The invention will be described below by way of example with reference to the appended drawing.

[0028] FIG. 1 shows a schematic illustration of a bumper at the front,

[0029] FIG. 2 shows a sonotrode in the prior art,

[0030] FIG. 3 shows exemplary embodiments for sonotrodes,

[0031] FIG. 4 shows an exemplary weld path.

DESCRIPTION OF THE INVENTION

[0032] FIG. 1 shows an exemplary embodiment with an exemplary bumper 1, as it is used in the front of a vehicle.

[0033] Mounts 2 for different sensors are fastened on that side of the bumper 1 which faces the vehicle. The mount 2 illustrated by way of example has in this case an annular support surface 3 and also a cylindrical receptacle 4. A sensor is plugged into the receptacle 4 and locked by way of the tabs 5 attached to the receptacle.

[0034] The support surface 3 can in this case of course also be of a square or rectangular, as well as asymmetric, configuration in order to ensure a precise determination of the relative position of the mount 2 on the bumper 1. A possible weld path 10 is indicated as a circular path.

[0035] The method according to the invention makes use of ultrasonic welding using a sonotrode 6, as is illustrated by way of example in FIG. 2. In this exemplary embodiment, the sonotrode 6 has two pins 7.

[0036] The mount 2 is spot-welded to the bumper 1 at the two pins 7 via such a sonotrode 6. A diameter of 0.8 to 1.4 mm has proven to be an optimum pin size in this case.

[0037] In the example of a bumper, the mount is produced from polypropylene with talc.

[0038] The welding operation is performed in this case step by step via a movement of the sonotrode 6 along the support surface 3 of the mount 2. In the example of FIG. 1, the sonotrode is moved along a circular line in the region of the annular support surface 3.

[0039] A linear weld path is illustrated in FIG. 4. The weld points 11 are placed in pairs by virtue of the use of a sonotrode with two pins. Welding step S2 takes place after welding step S1, etc. For welding step S1, a region of the energy manipulation 9 is identified in a similar manner in welding step S4.

[0040] In this case, after the first step of the welding, e.g. S1, the next step S2 takes place in a region 9 of the plastic element which was subjected already to a specific load as a result of the first welding step S1 and is in the tension-relieved state again. That is to say that, for the second welding step S2, less energy, stress and heat manipulation has to be applied than for S1, since the material has not yet completely cooled and hardened again. The step-by-step welding introduces integrally less energy into the components to be welded.

[0041] In this respect, a certain time interval has to be present between the individual welding steps S1, S2 . . . , in order to allow the material to be relieved of tension.

[0042] To carry out the method, the sonotrode 6 is moved mechanically along the weld path 10. This is realized by a suitable electric motor or a pneumatic drive or by a robot arm. The time needed to move the sonotrode over the workpiece is sufficient to allow the recovery process of the last weld to progress as far as possible.

[0043] The sonotrode 6 used has a pin here, but can also have 4, 5, 6, 7 or 8 pins.

[0044] Examples of different embodiments of the pins 7 are illustrated in FIG. 3. It can be seen here that the sonotrode 6 has either flat pins 7 which have a direct plane of contact with the support surface 3, or, as illustrated in the middle example, make contact with the support surface 3 in a tip 8.

[0045] The energy input is between 200-600 W of power output by the generator for the individual weld point.

[0046] By way of example, the distance between the individual weld points should be at least 5 mm, wherein the time interval of the placing of the weld points is determined by the mechanical options, but is preferably under 1 second.

LIST OF REFERENCE SIGNS

[0047] 1 Bumper [0048] 2 Mount [0049] 3 Support surface [0050] 4 Receptacle [0051] 5 Tabs [0052] 6 Sonotrode [0053] 7 Pins [0054] 8 Tip [0055] 9 Region [0056] 10 Weld path [0057] 11 Weld point