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Joachim Zoll,

Head of Business Unit Machine Tools at Siemens I DT MC, Erlangen

"Best accuracies in the end product with simultaneous increase in productivity can be achieved by avoiding re-tensioning processes"

Siemens creates 'concentrated cargo' at its stand at the EMO in Hanover - from the high-performance drive system open and flexible to the easy-to-use, modern user interface. Despite all energy efficiency, the user is in the foreground of development. development scout talked to Joachim Zoll about the products in focus as well as the state of development and the trends in drive technology for machine tools, which should not only be scalable in the future.

development scout: What is the current state of development of your drives for machine tools?

Inch: With 'Sinamics S120' we have developed a high-performance drive system which, in combination with the CNC control 'Sinumerik', is perfectly tailored to every drive task around the machine tool. In addition to the aspect of energy efficiency, easy commissioning, flexibility and scalability are of great importance to us. The digital interface 'Drive-Cliq' ensures minimized wiring costs. In future, this system will be implemented as an open encoder system by all encoder manufacturers. Through standardization, we would like to consistently minimize the variety of parts and storage costs and at the same time reduce the commissioning costs.

With the 'Sinamics S120 Combi' we have recently introduced a highly integrated compact inverter for simple lathes and milling machines (up to 16 KW spindle power), which is perfectly designed for small installation space and difficult environmental conditions. With this product, we answer the requirements for compactness and increased robustness with regard to temperature fluctuations, dirt or moisture, especially in the prevailing manufacturing conditions of emerging countries.

development scout: What are the biggest challenges your customers in the machine tool industry have to your company?

Inch: A major challenge for mechanical engineering and the metalworking industry is to optimize the productivity of the machine tool while keeping an eye on the complexity of processes. As a partner throughout the entire lifecycle, Siemens can support not only the entire machine life cycle from machine planning to the optimized machine with services such as mechatronic support, but also the entire manufacturing process through a complete CAD / CAM / CNC process chain for even more efficient processes and lower life cycle costs.

An optimal integration of the CNC control into the processes therefore already plays an important role on the CAD / CAM level. With Sinumerik, all functions and cycles in the generation of the NC program can be fully utilized via the post processor, making later production all the more efficient. But the consistency of the CNC control, the networking in the production, the integration of machine tools in the entire production environment with a modern data management offers a great added value for the industry. Further important aspects are the usability around the CNC operation as well as the surface quality of work pieces, which are benchmark for the CNC equipment. With 'Sinumerik Operate', Siemens offers an easy-to-use, modern user interface that not only offers innovative functions, cycles and animated elements, but also unifies the various types of programming such as step programming and high-level language programming in a modern look and feel under one interface. With the technology packages 'Sinumerik M Dynamics' including the new motion control 'Advanced Surface', the industry's demands for perfect surface quality, processing quality and speed for 3 and 5 axis milling machines are even better met.

development scout: How much potential energy efficiency is still available for the drive technology of machine tools?

Inch: With feed axes and spindles, Sinamics drive technology and system-optimized motors already available today can achieve a very high level of efficiency. However, in many machines, especially general-purpose machines, the installed drive power is higher than required for the specific processing by the customer. Such over-dimensioning prevents the efficiency optimum that can be achieved in individual cases actually being achieved. The biggest savings potential is therefore in system optimization. Above all, this includes the appropriate choice of the engine to the drive profile in order to achieve the optimum efficiency of the engine. Examples of such system optimization are the energy-efficient design and configuration of drive systems with the 'Sizer' project planning tool and integrated efficiency calculation, partial load optimization through energy-optimized flow control, multi-axis drive with common DC link, optimum grid energy utilization through regulated feed-in feedback and integrated reactive power compensation. On request, we can provide machine builders with a complete, optimally dimensioned control cabinet - also from an energy point of view. There are various cooling options, including, for example, the 'cold plate' or direct liquid cooling, which reduces the air conditioning requirements of the control cabinet and makes waste heat from the drives available elsewhere as process heat for the customer.

By contrast, ancillary components in the machine tool such as enclosure air conditioning, lubrication, coolant pump, air extraction, chip conveyor, compressed air supply, etc. lead to a high base load of about 50 percent of the connected load of the machine - and thus to extremely uneconomic machine conditions during production interruptions. Closer observations show that ancillaries are seldom driven by high-efficiency motors in favor of a low purchase price, or only in a few cases by a frequency converter. Here you can currently find the greatest potential for optimization.

In addition to drive technology, Siemens has other solutions for efficient energy management. With the 'Mechatronic Support' we offer a service for the holistic mechatronic optimization of the drive systems of a machine tool. The dynamic properties of the drive technology are incorporated realistically into the simulations.

The energy balance per produced good part can also be optimized by the virtual Sinumerik control for verifying NC programs in virtual machines. Part programs are thus verified and optimized on a virtual machine with virtual Sinumerik, which eliminates the need to produce sample parts on the machine and reduces the time required for machine utilization.

development scout: What accuracies are required today for milling, turning and grinding machines and what does this mean for your drive technologies?

Inch: Best accuracies in the end product with simultaneous increase in productivity can be achieved by avoiding re-tensioning processes. Thanks to the technology-overlapping approach and the openness of Sinumerik, it is possible to combine any type of technology to implement high-performance, high-precision machines. This production optimization is best supported by our integrated drive platform Sinamics S120 with its outstanding accuracy. Already today all involved algorithms are calculated from the setpoint generation via model-based control structures with active compensation algorithms to the setpoint output, the actual value acquisition and further processing in floating-point arithmetic with a resolution of 80 bit. For this reason, Siemens markets this process as "80 bit floating point accuracy". With this computing accuracy beyond the nanometer limit highest precision and surface accuracy in the production are achieved.

Of course, all actor / sensor components / interfaces involved, such as circuit breaker, motor, encoder signal acquisition trimmed to highest resolution, lowest ripples, highest temperature stability, lowest Polrucken / cogging torque, highest equidistance, intelligent algorithms, which leads to even better accuracy in machining ,

development scout: What trends do you see in the development of the powertrain for machine tools?

Inch: Due to the fact that high-tech machine tool manufacturers are also developing into markets of simpler machines and vice versa, an electric drive system has to be scalable for the various markets. At the same time, this must have a consistency that enables the machine tool manufacturer to use the different drives without additional effort.

The need for ever shorter development cycles places demands on the simple integration of drives and various sensor / actuator suppliers and types into the automation environment. Openness to rapid and custom technology innovation is necessary. Also required are central data management and the uniform procedure for engineering, commissioning, assembly, diagnostics, service and acceptance. Last but not least, we need integrated and highly integrated safety solutions.

development scout: Which innovations will you present at the EMO and what features are behind it?

Inch: At this year's EMO, we will be providing versatile answers to the questions and requirements of today's and tomorrow's metalworking industry. The focus of the Sinumerik 840D sl is on increased performance and functions for complete machining. But also the new powerful functions in turning and milling prove the innovative power of the open and flexible CNC system. The Sinumerik 828D compact CNC will also be the focal point of the show with new functions, enhanced performance and optimized speed control. Two further CNC variants complement the compact CNC family: the Sinumerik 828D Basic T and M for standard lathes and milling machines. There are also innovations around our new user interface Sinumerik Operate or the technology package Sinumerik MDynamics. Let yourself be surprised.

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