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 ultrasonic welding a plastic sensor mount to a plastic bumper of a vehicle, comprising: moving a sonotrode between a plurality of welding locations along a weld path defined along a region where the plastic sensor mount overlies the plastic bumper, wherein the welding locations are spaced from one another by distances of at least 5 mm, and wherein the sonotrode is moved between the welding locations at time intervals of less than one second; spot welding the plastic sensor mount to the plastic bumper via at least one pin of the sonotrode at each of the plurality of locations with a power output of the sonotrode set at between 200 W and 600 W; whereby the distance of at least 5 mm, the time interval of less than one second and the power output of between 200 W and 600 W relieve tension in the plastic materials of the sensor mount and bumper at adjacent subsequent welding locations.

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

3. The method according to claim 1, wherein the weld path extends linearly or circularly.

4. The method according to claim 1, wherein the at least one pin of the sonotrode terminates at either a flat or pointed end for engaging different contours on the plastic components to be welded.

5. The method according to claim 1, wherein the sonotrode is mechanically moved with at least one of an electric motor, a pneumatic drive and a robot arm.

6. The method in according to claim 1 wherein the sensor mount has a ring-shaped support surface, and wherein the weld path extends in a circle shape along the support surface.

7. The method according to claim 1, wherein the at least one pin of the sonotrode has a diameter of 0.8 to 1.4 mm.

8. The method according to claim 1, wherein the sensor mount is made of a polypropylene with talc.

Description

DRAWINGS

(1) 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.

(2) The invention will be described below by way of example with reference to the appended drawing.

(3) FIG. 1 shows a schematic illustration of a bumper at the front,

(4) FIG. 2 shows a sonotrode in the prior art,

(5) FIG. 3 shows exemplary embodiments for sonotrodes,

(6) FIG. 4 shows an exemplary weld path.

DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows an exemplary embodiment with an exemplary bumper 1, as it is used in the front of a vehicle.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) In the example of a bumper, the mount is produced from polypropylene with talc.

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) The sonotrode 6 used has a pin here, but can also have 4, 5, 6, 7 or 8 pins.

(19) 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.

(20) The energy input is between 200-600 W of power output by the generator for the individual weld point.

(21) 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

(22) 1 Bumper 2 Mount 3 Support surface 4 Receptacle 5 Tabs 6 Sonotrode 7 Pins 8 Tip 9 Region 10 Weld path 11 Weld point