Start up made easy - Flexible servodrive for butter packing plant
Whether it is a new product or a retrofit, starting up a machine for the first time is always an exciting moment. The same feeling arises when integrating drive technology. This makes it all the more satisfying when start up of the drive on site goes so smoothly that even experienced mechanical engineers are amazed. The following two applications demonstrate how easily this can be achieved using servodrives.
WAL Mess- und Regelsysteme GmbH of Oldenburg, northern Germany, develops and produces measurement systems and controllers for industrial use. The main purpose of these systems is to measure and control physical variables. The company also manufactures custom solutions for the food industry. One such solution is a fully automated filling and packaging plant for butter, vegetable fats and other food pastes (Image 1). Yaskawa servodrives are used in both the butter packaging plant and an additional module connected to it – a carton erector (Image 2).
Reliable processing
The fully automated butter filling and packaging plant fills and packages 25 kg units of butter. The plant guides an empty carton to the filling position, lines the inside of it with foil and then fills it. This is done with the aid of a drive, which enables the plant to pull the foil off a roll (Image 3), cut it to the required length and lay it around the filler head. The filler head is then inserted into the carton together with the foil. When the filler pipe pumps the butter into the filler head, the head thus “swims” up to the top of the package on the surface of the butter. Durability and hygiene were key considerations when it came to designing the machine: The interior sections needed to be easy to clean, and fully automated CIP (Cleaning in Place) was a must for every component that comes into contact with the product, as well as the inside and outside of the filler head. The modular design of the plant keeps start up times short and makes it easy to expand.
The motorized foil supply unit unrolls evenly without running on. Together with the exact foil lengths, this ensures that packaging is carried out reliably. In the past, the foil was pulled off using a stepper motor. Without regular maintenance, this motor often broke down. The difficulty was compounded by the design of the stepper motor, which prevented it from reaching its maximum torque unless at a standstill and caused the torque to decrease as the unit built up speed. The act of pulling on the foil roll increasingly required a dynamic response that the stepper motor was unable to provide. A servodrive was required (Image 4). Mathias Willner (Image 5), Technical Director at WAL Mess- und Regelsysteme GmbH, explains: “We sell our plants not just in Europe, but in the USA as well. Because of this, one of the key requirements for our new servodrive was that it had to support both Profinet and EtherNet/IP as communication media. We found a good solution in the Sigma7 (see technology box) from Yaskawa.” Both the European and the American models of the butter filling plant are fitted with the same AC servo motor. The only change is the servo amplifier, which is chosen to match the required bus interface in each case. The new plant also provides another improvement that has delighted Mr. Willner: “In some countries, we were having problems with imprecise power supply voltages. That was a real challenge for the stepper motor, but the servodrives keep running reliably even in the face of fluctuating power supply voltage.”