In the printing industry, it is standard practice to take a larger role of labels and process it into smaller ones. Simply, because not all consumers have the infrastructure to handle these large rolls or they don’t need that many at a time. The larger label manufacturer specialises in large volumes and therefore usually only own large printers. However, it becomes a problem for them to interrupt a mass production line to make a few smaller roles for a client. As a result, there is a great need for small tabletop rewinders that can rewind small rolls from the big ones.
Our Solution to the Problem:
In most cheap rewind applications, there are no form of closed loop or constant torque control involved, because the technology is just simply too expensive for what’s been required. Therefore, some tabletop rewinders use only speed control and do not require expensive servo drives with encoders. HmT decided to use the new sensor less vector control algorithms inside the LSis S100 VFD to do excellent constant torque control, without the need for any encoders. Without any external feedback, torque control tolerances within 1% was achieved. We further improved the system with an HMI and PLC to add functions such as progressive torque rewinding, recipes and cut to length. The future goal is to be able to do label slitting on the same machine without much change.