Control and drive technology for a complex wood processing machine
22. July 2019
No household or construction site is complete without a folding ruler or yardstick – and yet, the handy measuring device is barely given a second thought. From an automation technology point of view, however, its production is a complex process, as a current solution from the Czech special purpose machinery designer VÚTS shows. Control and drive technology from Yaskawa ensures perfectly synchronized sequences of movement – and thus a 50 percent increase in productivity.
The Czech manufacturer of wooden products, Metrie spol. s r.o., has specialized in the production of folding rulers or yardsticks for almost 100 years, or since 1922 to be precise. And these are far from simple products: A folding yardstick, otherwise known as a double meter stick, is made up of no less than 48 individual parts. Despite this, the length deviation between the many thousands produced is at most 0.7 mm.
The largely automated production process requires a total of 16 work steps. In order to increase productivity and make the process more stable, the company decided it was time to replace an older, cam-controlled machine with a contemporary system featuring synchronized sequences of movements. The assignment was taken on by the experienced Czech special purpose machinery designer VÚTS, a.s., which is located in Liberec, near the Czech border with Poland and Germany.
The solution from the VÚTS design engineers involves a total of 16 stations arranged around a central, carousel turning station that can rotate through 360°. Several processing steps, such as drilling and milling, can then take place at the stations in parallel. Additional stations are used for loading and unloading the machine or for measuring processes as part of quality assurance. The major benefit of this concept is that the machine does not have to be mechanically retooled in the event of a product change. The required parameters can simply be set via the HMI control panel. The machine is capable of performing 60 cycles per minute, which equates to at least a 50 percent increase in productivity over its mechanically controlled predecessor.
Control and drive technology from Yaskawa
Components from Yaskawa – specifically the MP3200 machine control system as well as servodrives from the Sigma-5 series and ten V1000 inverter drives – are used both to control the complex, synchronized sequences of movements and to drive the carousel turning station as well as a further 20 axes.
It was an easy decision for the team at VÚTS, as Jan Kondr from the Czech Yaskawa partner CNC Technology, spol. s r.o. explains: "VÚTS is very familiar with the MP controllers in particular and has full confidence in the components and solutions from Yaskawa. When this challenging assignment for Metrie arose, the engineers were in no doubt about using Yaskawa's control and drive technology in this instance – particularly as it is ideally suited for perfectly synchronized movement sequences."
MP3200 high-performance controller
The MP3200 high-performance controller from Yaskawa delivers the highest standards in high-speed performance and accuracy. Alongside the standard MP3200 version, the MP3200iec variant has been designed specifically with the European market in mind. With its IEC development interface, it ensures simple, fast, and user-friendly programming in accordance with the IEC 61131-3 standard.
An extremely powerful CPU allows up to 62 axes to be controlled. As a result, greater precision can also be achieved in complex high-speed applications. Simple usability and easy maintenance were also key focal points during development.
Featuring real-time MECHATROLINK-III Ethernet interfaces, the controllers enable simple integration of servo axes into synchronous groups. The CPU size and base unit can be selected freely, meaning that, in the event of future expansion, the performance can be increased by adding a larger CPU. Several base units are available for input and output modules – with either three, five or nine slots depending on application – as well as the option for a cross-rack expansion.
The components in the MP3000 series deliver a high level of performance. Power can be evenly distributed between the axis control and PLC functionality. This ensures that sufficient computing power is available for PLC functions even during highly complex curve movements and high cycle rates that require a great deal of processing power for the motion control component. The controllers are thus at least 1.5 times more powerful than their predecessors.
Sigma-5 servo drive system
The machine designed by VÚTS incorporates two servo drives from the Sigma-5 series. The carousel is moved very precisely by a single-axis motor with 4.4 kW power. A 400 W servo system with 20 single axes works in the processing stations.
The Sigma-5 servo system range from Yaskawa contains servodrives consisting of servomotors, servo amplifiers and a powerful SigmaWin+ engineering tool. The range includes rotary motors, direct drives and linear motors. The standard models provide both faster positioning times and high positioning accuracy of less than 1 µm.
To help integrate the system into comprehensive automation solutions, there are—in addition to MECHATROLINK-III—modular interfaces for EtherCAT, CANopen, POWERLINK and MECHATROLINK-II. Thanks to an auto-tuning function and an automatic filter function to suppress vibration, the system continues to function quietly and with a minimum of vibration even at low speeds. Optimal operation is therefore guaranteed even for high-precision applications. At the same time, machine wear is reduced. This has a positive effect on subsequent costs.
Sigma-5 components can be started up and diagnosed quickly and easily using the user-friendly SigmaWin+ software. Manual settings and specialist technical knowledge are not required. For example using the auto-tuning algorithm, two axes can be accurately configured in high performance machines in less than two hours, instead of the normal eight.
V1000 inverter drives
A total of ten V1000 inverter drives are integrated into the drive solution – also via a MECHATROLINK-III interface. These move the drilling and milling spindles in five processing stations. Two processing units work in each of these five stations – one for the top and one for the bottom of the wooden workpiece.
The V1000 inverter drive series from Yaskawa provides a reliable and efficient solution for the safe and accurate control of permanent magnet motors. With its highly dynamic open-loop vector control, the inverters provide the optimum choice for driving both asynchronous and permanent magnet synchronous motors in the output range from 100 W to 15 kW.
Launched as one of the smallest compact inverter drives in the world, the V1000 is characterized by an extremely small footprint. In addition to its compact dimensions, it is also suitable for side-by-side installation, i.e. for mounting several devices directly alongside each other. This means that the inverter drives take up even less space in the switching cabinet. A patented hybrid cooling element made from a special alloy compensates for the reduced ventilation effect, thus preventing the inverter drives from overheating.
An integrated dual rating function means that the inverter drives can work at 120 percent overload in normal duty mode in applications that require low overload. This means that a comparatively smaller inverter drive can perform the work for which a larger drive would otherwise be required. Moreover, the braking resistor unit reduces the deceleration time by around 50 percent. Finally, the V1000 allows a rapid response to changes in load and speed, thereby optimizing the machine performance.
In a complex wood processing machine, the MP3200 high-performance controller, Sigma-5 servo drive system and ten V1000 inverter drives ensure perfectly synchronized movement sequences and thus a 50 percent increase in productivity compared to a mechanical solution. The design engineers from the Czech specialist machine constructor VÚTS therefore knew they made the right decision opting to use the control and drive technology from Yaskawa. Planning for a second, similar machine for Metrie is already underway.