The Future of Manufacturing: A Common Language for Robots and Machine Tools

CNC machine tools and robots used to inhabit different worlds. Their control systems couldn’t talk to each other. Now, Siemens’ Run MyRobot bridges the gap by integrating robots into the Sinumerik CNC controls for machine tools.

 

by Bernd Müller

Modern factories would be unimaginable without Computerized Numerical Control (CNC) machine tools. Thanks to CNC, machines can bore, mill, and grind workpieces that have complex shapes with high precision. What’s more, CNC machines are now increasingly being supported by robots that place and remove workpieces in the machines. This combination is intended to speed things up. And it really does – according to the International Federation of Robotics, the number of handling robots serving machine tools is growing at a rate of 15% per year.

Increased Precision for Robots

There is just one problem. Machine tools and robots are separate entities and are programmed separately. Machines use a CNC control system such as Sinumerik from Siemens, whereas robots use a controller from their manufacturer. A really seamless integration of the processes is not possible under these circumstances, and programming robots requires a significant amount of know-how. Ideally, machine tool operators, who are skilled in programming Sinumerik on machine tools, should also program associated robots.

Robot and Machine Tool: Different Aspects of Integration

This is exactly the goal that Rainer Adolf and his team at Siemens’ Digital Factory division in Erlangen, Germany have set for themselves. It has launched Run MyRobot on the market – an extension of Sinumerik that enables robots to be seamlessly integrated into the controls of CNC machines. The extension makes programming a robot significantly easier, so that a machinist doesn’t need to acquire extra know-how. As a result, a robot’s movements can be better adapted to the working environment and much more precise.

 

Controllers from robot manufacturers are optimized for the fastest possible movements along unchanging paths, for example when welding in the automotive industry. If, however, robots are required to perform freely-chosen and frequently changing movements, their controllers are not precise enough. “This is due to the mathematics of control algorithms, which are simplified and optimized for speed,” says Adolf. “Sinumerik, in contrast, utilizes more complex mathematics.” For example, sophisticated algorithms in machine tools automatically optimize parameters such as machining rate or damping while taking account of friction and the contours of a workpiece – and they do so in advance, before the tool has been moved. These algorithms also increase precision when steering a robot. In addition, Sinumerik, which is extensively used as a comprehensive solution in Industry 4.0 scenarios, offers simplicity of operation and powerful work preparation tools despite its complex range of functions.

Run MyRobot makes programming a robot significantly easier, so that a machinist doesn’t need to acquire extra know-how.

Precision in Aerospace Engineering – to a Tenth of a Millimeter

Zum ersten Mal auf das Präzisionsproblem aufmerksam wurde der Siemens-Experte bei einem Projekt für die Flugzeugindustrie. Airbus und Boeing bauen die Rümpfe ihrer Jets aus Kohlefaser, um Gewicht zu sparen. Dazu fährt eine Maschine in der Größe eines Krans am Rumpf entlang und legt das klebrige Gewebeband auf. Die Maschine ist eine Spezialkonstruktion, deren Kosten sich auf einen zweistelligen Millionenbetrag belaufen. Ein auf Schienen montierter Standardroboter würde nur einen Bruchteil kosten und wäre obendrein flexibler. Doch erste Versuche der Anlagenhersteller scheiterten, weil der Roboter mitunter Zentimeter vom Weg abkam. Im Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung (IFAM) in Stade ist man da bereits weiter: Ein Universalroboter arbeitet dort beim Belegen der Rümpfe mit Kohlefasergeweben auf einen zehntel Millimeter genau – dank Sinumerik Run MyRobot und einer ausgeklügelten Laserkalibrierung des Roboters.

From Sidekick to Partner

Until now robots working in collaboration with CNC machine tools have been limited to simple handling tasks such as placing and removing workpieces. Run MyRobot opens up completely new possibilities in production, namely hybrid processing. For example, let’s say a machine tool has milled a metal workpiece which, however, has to be deburred and polished. A nearby robot might then hold of the workpiece and perform postprocessing, using its own built-in grinding tool. In the meantime, the machine tool would already be milling the next component. Here too, the decisive advantage is Sinumerik’s high level of precision. A controller from a robot manufacturer could never bore holes or carry out fine grinding work to a precision of fractions of a millimeter, but Sinumerik can. Robots can even print – using a 3D printing head attached to a robot’s tool holder. Such a head can print fiber-reinforced plastic components.

 

A demonstrator is now in operation at Siemens in Erlangen. Productivity gains of ten percent are certainly there, says Rainer Adolf. In a sector that celebrates productivity gains of a few percent as success, that’s a real wake-up call. “Our customers are beating a path to our door with new requests.” he adds.

The integration of robots into Sinumerik makes them part of a greater whole – the digital factory and the digital company.

For Robots of All Types

Run MyRobot requires direct access to a robot’s electrics and mechanics for the hybrid manufacturing applications mentioned above. Comau, for instance, an Italian manufacturer for industrial automation solutions, offers complete access to the mechanics of its robots and thus perfect conditions for Sinumerik, which controls the company’s robots directly using its CNC algorithms. The reward is simple operation and high precision.

 

Other robot manufacturers only offer systems with integrated control electronics, but here too, Sinumerik opens its interface for new concepts. In the simplest variant, Run MyRobot Handling, Sinumerik uses commands from standardized libraries, e.g. from robotics specialist Kuka. In Run MyRobot Machining, Sinumerik links up to a robot’s controller via a special digital interface. This frees the user to decide which robot to buy and which machine tools to operate it with. “Not all from a single source, but all out of the same mold,” is the Siemens motto.

Vast Savings Thanks to Digital Twins

The integration of robots into Sinumerik makes them part of a greater whole  the digital factory and the digital company. The entire value creation chain, including production facilities, will in the future be represented, simulated, and optimized in a digital twin before the first machine actually enters service. To this end, Sinumerik has, for example, established interfaces to CAD programs for years and offers a complete virtual CNC kernel. A CAM postprocessor derives the appropriate processes from engineering design data, and adaptations are first run in the model. This speeds up engineering and collaboration dramatically  especially between continents  and simulates realistic parameters such as computing time and specific features of associated algorithms in the process.

 

All of this enables substantial savings, since the configuration and commissioning of a robot accounts for half of total costs. “The simulation of robots and handling systems with the help of digital twins enables new manufacturing processes in factories to be planned and introduced much more rapidly. What’s more, digital solutions reduce the complexity of procedures. Fewer control systems are necessary, because Sinumerik can take over controlling robots,” says Klaus Helmrich, the member of the Managing Board of Siemens who is responsible for the topic Digital Factory. “In this way, digitalization opens up new possibilities for flexibility, enhanced efficiency, and quality in production.”

 

2018-06-20

Bernd Müller

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