ENHANCED CYCLE EFFICIENCY THANKS TO ROTARY INDEXING MACHINES
3 July 2012
With maximum flexibility, minimum setup times and extremely short non-productive times, rotary indexing machines like the Winema RV 10 Flexmaster are breaking into the domain of cam-controlled machines. Designer Eckhard Neth, Managing Director of Winema Maschinenbau GmbH in Germany, discusses the road to maximum output.
Our customers want maximum output with the shortest possible setup time. This is particularly true for price-sensitive mass products such as plug pins, cam discs and cable connectors made of all types of metal materials. However, ancillary times below 0.3 seconds have only been possible up to now thanks to the use of cam-controlled machines, which require compromises in the machining process and often incur setup times of one half to two shifts.
With the newly developed RV 10 Flexmaster, which is suitable for small work pieces from two to 13 millimeters in diameter, Winema now boosts productivity by 20 percent compared to more conventional solutions. The rotary indexing machine boasts a complete setup time of around 1.5 hours – four to six times faster than comparably equipped cam-controlled machines. For parts families with an annual volume of five to ten million units, we surpass the speed of cam-controlled alternatives and combine this with the advantages of CNC technology for enhanced flexibility. Up until now, no machine manufacturer has been able to satisfactorily meet these requirements for the entire work piece spectrum. The highly dynamic processes are made possible by the extremely high rigidity of the load-bearing components and by optimizing the masses of the moving parts as well as extremely tight manufacturing tolerances.
54 electrical and hydraulic CNC axes
On account of the compact machine form, only hydraulic drives can be used for linear motions. They enable rapid acceleration and an extremely dynamic control response. This means that the use of wearing parts to transfer force is obsolete. Additionally, the heat produced by the drive can be easily dissipated at the hydraulic station outside the machine tool – significantly reducing thermal stress.
From our perspective, Rexroth offers the only complete system on the market that provides control units, hydraulic controllers and control valves from a single source. Consequently, we are using its IndraMotion MTX CNC system solution for the first time in our new RV 10 Flexmaster. It meets all requirements for quality of control and dynamics for a large number of axes. In the MTX performance version, it controls the 54 CNC axes of the RV 10 Flexmaster, 27 of which are IndraDrive spindle drives. Thanks to its lean architecture, the CNC core can also execute the Flexmaster’s complex tasks in an extremely short time, thus reducing non-productive periods. The highly dynamic torque motor increases output even further. It positions the indexing table so precisely that the hydraulically clamped spur gear can engage immediately. This enables us to reduce unproductive ancillary times to less than 0.3 seconds.
Unsurpassed functionality in control, user interface and handling
Rotary indexing machines with a high number of axes place exceptional demands on the functionality of the control system, the user interface and data handling. Transferring our many years of experience to a new control concept and realizing further improvements with this step is an enormous challenge. But early in the development phase, multiple laboratory tests at Bosch Rexroth contributed greatly to our progress. By means of simulations, we were able to decisively enhance the control technology basis of the mechanical components with regard to the desired quality of control. Not only were all requirements of the specification met, but the extremely constructive and creative collaboration generated additional ideas for further optimising operating convenience and ease of retooling before the start of series production.
The Rexroth HNC100®-3X motion control-system assumes the micrometer-precise control of the hydraulic feed axes. Its software takes into account all special characteristics of the fluid technology, thus decoupling the drive from the control level. IndraWorks provides the same software tools for the electrical commissioning of the hydraulic axes as for the other drives, which greatly simplifies our work.
Real-time communication cuts cycle time
All electrical and hydraulic drives communicate with the controller via sercos. The Ethernet-based automation bus uses strictly deterministic real-time mechanisms. By combining HNC with sercos and the IndraMotion MTX, output is increased by 20 percent compared to solutions previously available and we can even machine two work pieces simultaneously with no difficulties.
It is of course an advantage that the entire automation was supplied by a single source to greatly simplify interface matching. Bosch Rexroth supported us intensively throughout the entire development phase and thus significantly reduced our time to market.
Further information on Bosch Rexroth can be found at www.boschrexroth.co.uk.