Beverage: the solutions

This month, our “Did you know that…?” column is taking a look at some problems and solutions in the world of beverages, focusing especially on rotating bottling lines. Here are a few examples:

Inertial unbalancing. In these applications, there are often high inertial loads such as carousels and star wheels. Rexroth has a vast range of high inertia servomotors and frameless torque motors that guarante the optimisation of the inertial unbalancing between the load and the motor. In this way, good control is guaranteed during all the processing phases, including the transitory ones.

Cogging torque. The torque swing, even at constant rotation speeds, is due to the construction geometry of the brushless motors (misalignment of the magnetic fields) and is particularly troublesome at low speeds. In the Rexroth drives, this effect is compensated by the advanced cogging torque compensation function.
 
Tracking error. To obtain better control of the mechatronic system, we use different following error management parameters at constant speed and during the transitory phases.

Stabilisation of the mains voltage and synchronized stops in the event of a voltage drop. In many countries, the oscillation of the mains voltage is a problem that arises quite frequently. The regenerative stabilised power supply unit of Rexroth's HMV-R range successfully overcomes this problem: it regenerates in the mains, and stabilises the DC bus at 750V regardless of the voltage or of any possible voltage oscillations. The stabilised DC bus also means that a blackout (which would trigger an emergency stop) can be detected immediately, thereby guaranteeing the constancy of the synchronism thanks to the energy produced by the decelerating axes.

Independent, decentralised drives for star wheels and carousels. The rotary filling lines are evolving towards a type of design with independent drives for the star wheels and carousels.
The new range of motors with integrated IndraDrive Mi servo drive is a step forward in this sector, thanks to the daisy chain connection of all the drives via a single cable. The new version of Indradrive Mi offers several important innovations: the multi-protocol command interface (Sercos III, Ethercat, Profinet, EtherNet/IP), the possibility to connect external peripherals (I/Os, solenoid valves, etc.) directly to the servomotor, and the introduction of certified safety functions (such as STO) to create safe areas based on your own particular requirements, thanks to the safe disconnection of each single axis.

With regards the software, the following functions are particularly handy
Master change on the fly; in the event of an error on an axis, you can synchronize all the other axes with the one that is stopping, thereby guaranteeing the following of the slaves in this critical deceleration phase as well;
Operating mode change; it is possible to change quickly from a position control to a speed control or even a torque control. This can be the case in capper units, that require a position control during the approach phase and then a torque control for the final tightening.