| Analogue position sensor optimising ultrasonic welding systems |
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In order to cope with the requested material diversity in automotive engineering, flexible production systems are needed. Therefore the Lühr Group opts for Turcks analogue magnetic field sensor WIM. |
Due to direct mounting on the pneumatic cylinder the change over to new materials is possible during on-going production process without manual adjustment.
Today, ultrasonic welding systems are an integral part of interior construction in the automotive industry. They shape the plastic components like instrument panels, centre consoles or door trims as intended by the engineer. The ultrasound is produced with a generator, the mechanical resonance unit, consisting of a converter, amplitude transformer and sonotrode, is mechanically linked to the generator and mounted on a pneumatic cylinder. Mechanically produced vibrations generated by the converter are carried forward under pressure by the sonotrode to the thermoplastic joining parts.
The ultrasonic energy transmitted into the joining zones creates the molecular and interfacial friction, resulting into warming and melting of the plastic components. The ingress depth of the sonotrode in the plastic material is a measure for the quality of the joining parts, whereupon each material has its own specific optimum value. As long as only one product is assembled, flexibility is not required because the optimum ingress depth remains constant. Especially in the automotive industry various materials of different thickness have to be processed.
Material diversity requires flexibility of systems
As one of the leading manufacturer of ultrasonic welding systems even the Lühr Group has to implement flexibility demands of their customers. Magnetic field sensors were used in the past to adapt the US-ultrasonic welding systems of the Lühr Group to the material change. For each changeover, i.e. from leatherette to plastic, the operator had to change the switch point of the sensor manually in order to attain the optimum values for the currently processed material. This was associated with a production stop and long retrofitting times...
The author:
Dipl.-Phys. Ing. Holger Spies is Product Specialist
for Position and Proximity Sensors
at Hans Turck GmbH & Co., Mülheim a.d. Ruhr
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