Yaskawa controller optimizes chocolate production

As an enhancement to the modular components used in the production of chocolate (depositing machines), Knobel AG and SwissDrives AG jointly created the HighFlex handling system, which perfectly complements Knobel’s modular production approach. In creating the system, particular importance was attributed to its flexibility and minimal servicing requirements. In chocolate production, the depositing moulds must be implemented and the chocolate formed at high cycle rates. Knobel satisfied these requirements with a patented procedure, ingenious design and the use of high-quality components.
At the heart of the HighFlex system are two linear motors from Yaskawa, both of which use the same guide. The head module, which is mounted according to the scissor principle, travels in x- and z-direction based on the absolute or relative movements. Depending on the application, a grabbing, vacuum, cutting, turning or other tools can be fitted to the same head.
A teach-in function enables the programming of different processing positions. By means of a transformation, the values from the “head coordinate system” are transferred to the “motor coordinate system”. The head load is then moved from one processing position to the next via the time-optimized path on the basis of a mathematical curve calculation. This prevents any jerking movements and allows the motion dynamics to be adapted to the individual products. In some movements, the product (praline/chocolate) travels with the machine. These special circumstances can be addressed by means of adapted motion dynamics.

Thanks to the clever mechanism, oscillation and vibration are largely eliminated. The residual machine resonance is suppressed by innovative control algorithms in the servo amplifiers of the linear motors. The entire system is characterized by its extremely high control quality, thus achieving great accuracy across the whole motion sequence without overshooting at the end of the movement.
The entire motion sequence is coordinated by a Yaskawa motion controller, which enables position-specific generation of all necessary pre-signals. This allows a pneumatic grabber, for example, to start its motion once the head module has passed a specific position. The movements thus begin to “converge”, which results in an enormous boost in performance.
Where cycle times were previously around 10 cycles per minute, the new systems can achieve up to 30 cycles per minute – and the machine movements are buttery smooth. Mechanical strain is minimized, the service life of the machine is increased and servicing/maintenance requirements are all but eliminated, largely thanks to the use of linear motors. In this system, the linear motor functions as a direct drive without mechanical power transmission, while the positioning system takes the form of a non-contact optical reading system. All that is required is regular lubrication of the linear guides.