Lagniel SAS, France, produces automation assembly lines in continuous motion at very high speed. Two new machines were designed and built, which deliver up to 600 ultrasonically welded parts per minute. Previously it tooks 5 years to develop the technology. Herrmann Ultraschall has contributed to engineer and incorporate the ultrasonic welding process into the machine.
After initial trainings at Herrmann Ultraschall to broaden their understanding about ultrasonic welding, Lagniel developed as a first step a 35 kHz rotary ultrasonic test bench.
A continuous motion machine is basically a servo-driven rotating dial where the tools motions are cam-driven. The dial assembles parts continuously, controlling the approach and timing during the travelling around the circumference. Additional combined process can also be added like extra-force with controlled pneumatic pressure cylinder, like small motors for rotation, etc…
Using the decomposition of the movements, ultrasonic welding was made possible : approaching time to sonotrode, welding upon contact, keeping pressure after energy is shut down, cooling, removing the sonotrode contact without any impact on the dial speed.
One generator controls up to 6 sonotrodes. Energy, distance to sonotrode, pressure, time were the parameters to combine for achieving the welding process. Controlling mechanically the fixtures while having the proper response from the generator have been successfully challenged.
High performance generator
Among various suppliers, Herrmann was the only one to have the generator and control system with the desired characteristics:
- To switch quickly to different welding parameters memories
- To transfer fast enough all the process data thru the requested bus system, from the controller to the generator and from the generator to the line supervisory controller, which is a must in medical market.
- To offset normal mechanical tolerances of the machine
Ultrasonic engineering with DIASIM-Software
Hermann ultrasonic experts contributed greatly to determine the right welding parameters according to the part dimensions, the material properties, the machine speed and other specific customer requirements.
Hermann Ultraschall programming engineers also developed a dialog-simulation software to enable process set-up and optimization. Some features of the software very helpful such as broadening the process tolerances and stability, such as display and traceability of all the welding data recorded in the memories for further investigations.
Outlook and Realizations
The continuous motion machine with incorporated ultrasonic welding is an impressive combination of mechanical assembly at high speed and a complex and sophisticated ultrasonic technology.
LAGNIEL, with more than 30 years experience of Lagniel in dial cam/process control, and HERRMANN, providing high tech generator coupled to DIASIM software, together, did extensive teamwork that leads to this successful achievement.
Six complete continuous motion machines have already been installed in agriculture irrigation and medical devices applications. Using 4 generators to control 24 dial positions, a speed of 600 parts per minute is achieved as nominal production run. Further development will continue to reach even higher speed.
The ultrasonic welding assembly process can be extended to many applications, perfume spray nozzles, pens, food packaging components, batteries, syringes, etc. … In addition, other technologies can be incorporated like crimping, laser marking, and labelling.