Seven

Seven

The smart automotive factory of tomorrow demands flexibility. Painting robots, too, are having to take on ever more varied tasks. Dürr’s new generation of robots has seven axes of rotation, which makes them especially maneuverable. They can also feed a large amount of information into the digital data network.

Dürr’s new painting robot hums quietly in the test center in Bietigheim-Bissingen. It tilts forward, rotates, then extends its arm right out. The new EcoRP E043i robot’s strength is its maneuverability. Thanks to its additional joint, it can carry out maneuvers which were not possible previously. “It’s significantly more versatile in use than all preceding models,” says Detlev Hannig, Head of Robot Systems and Mechanical Engineering at Dürr.

Thanks to smart technology, automotive manufacturers can now paint completely different vehicle models in changing colors on one and the same line. The robot has to adjust to changing vehicle shapes within seconds. It moves the atomizer, which sprays the paint, precisely over the surface, while adhering to strict specifications in terms of distance and speed. This is essential in ensuring that the paint is applied to best effect. Maneuverable robots are therefore especially important in meeting customers’ ever more stringent requirements.

7th axis

It’s only one more axis for the robot – one giant leap for maneuverability and efficiency in automotive paint shops. The seventh 
axis of rotation extends the robot work zone, enabling it to paint vehicle models with completely different outlines on a single line. It replaces an expensive and space-grabbing rail, along which the robot had to move to and fro in the past.

» The new EcoRP E043i is significantly more versatile in use than all preceding models. « Detlev Hannig, Head of Robot Systems and Mechanical Engineering

No room for rails

A conventional painting robot has six joints – the technical term for which is axes. Although these make it fairly mobile, it’s still not enough to reach really difficult-to-access corners inside a vehicle body. That’s why painting robots often have to move forward and backward on rails to extend their work zone. “This procedure is effective, but expensive,” says Hannig. Because rails need space and have to be maintained. Dürr’s developers looked for a more elegant solution and opted to use a seventh axis of rotation to render the rails superfluous and extend the robot’s work zone. Rotary axes, unlike linear ones, are especially mobile and inexpensive.

Hannig set about his task at the beginning of 2014 together with a team of mechanics, engineers and drafting technicians. The first question they had to settle was where to locate the seventh axis. “We spent more than a year exhaustively discussing this issue,” says Hannig. They then turned to a special computer program and drafted the robot digitally, including its electronics, pneumatics and hose routing. Then, using comprehensive simulations, they improved one detail after another. Is there good access to the component for a service technician, if required? An exact 3D model helped to take account of such aspects in the design, too. In December 2015 the first metal prototype finally moved.

In human terms, the seventh joint is approximately at hip level. The first robot arm can be tilted to the side by rotating this additional axis. It can also more easily overcome obstacles. If a body passes with its doors open, the arm articulates upwards out of the way at the appropriate location, without interrupting its work. Another important aspect for the developers was designing a reliable and robust robot that is easy to maintain.

Smart hazard control

The EcoRP E043i is better than its predecessors in many respects. Its axes have more powerful motors and gears. This enables the arm to jump to a new position after an extremely short pause in order to continue painting the body at a different location. Although these dead times last just a few seconds per vehicle, they can add up to more than an hour a day in a paint shop.

However, the robot’s new mobility also entails risks. It would be conceivable, in light of the additional axis, 
for the arm to swivel out of its work zone, smash through 
the booth wall and put people in danger. With that in 
mind, Dürr has developed a smart safety controller for the EcoRP E043i. Sensors constantly capture the positions of the joints and, using this data, the controller continuously recalculates the position of the robot arm. “In the event of danger, the system shuts down,” says Jens Häcker, Senior Manager Product Development Control Products.

Behr 3/6

1984

Behr 3/6
First steps in robot technology: painting robot with a hydraulic drive, though maintenance-intensive and lacking in dynamic movement.

EcoRP 6/7

1998

EcoRP 6/7
Servomotors and a fiberglass arm mean that the robot responds substantially more dynamically.

EcoRP E/L XX3

2005

EcoRP E/L XX3
Lower weight, even better performance, a working height of 1.90 m – the new generation is faster, more maneuverable and, thanks to its modular construction, available as a family 
of robots.

EcoRP E/L XX3i

2016

EcoRP E/L XX3i
New arrival: the latest generation adds a 7-axis robot. The additional axis makes it a really efficient mover, while its smart controller ensures the transfer of data.

The fruit of decades of work

The EcoRP E043i is right at the leading edge of the products that Dürr can offer in painting technology. It has benefited from decades of experience. As recently as the 1990s, painting gantries were still the norm. They sprayed the large body panels with paint. Human spray painters, working with a spray gun and respirator in a hot and humid booth, then dealt with those areas which were difficult to access. That was time-intensive, and a great deal of paint also missed the vehicle body.

Dürr has had painting robots for more than 20 years. The first ones still worked with a hydraulic drive. In the late 1990s developers fitted the robots with servomotors, which delivered more dynamic movement. 2005 saw the launch by Dürr of the EcoRP E/L family. The seven-axis painting robot is now the latest generation. The first two such robots were installed on a painting line at the VW plant in Wolfsburg, Germany, in December. There they are undergoing beta testing – i.e. field testing on the production line.

The EcoRP E043i offers everything the smart factory of the future needs. It’s a straightforward matter to connect it to a company’s central data network. Sensors capture its components’ temperature, operating hours and degree of wear. The controller transmits this information to higher-level maintenance and control systems or to the Dürr Service Cloud. This technology enables data from a number of paint booths or even entire paint shops to be merged. Maintenance visits can be scheduled centrally, and the robots’ health can be monitored remotely.

The good-looking one with the smart control cabinet

The robot’s controller delivers the data. It is located in a control cabinet next to the painting line. The almost airtight housing protects the electronics against soiling. However, the electronics generate heat, which raises the temperature in the control cabinet. In the past, therefore, a power-guzzling cooling system was required. “Up to an ambient temperature of 40 °C, the control cabinets for the new robot no longer need that,” says Häcker. The heat generated by various parts is routed to the back of the control cabinet and discharged via an air duct, which saves energy.

A modern robot not only has to work smartly, it also has to be easy to operate – for example, if it needs to be reprogrammed when the car factory changes models. “That’s why we attached great importance to the easy operation of the additional axis,” says Häcker. The customer merely determines the key points on the body for painting and specifies the elbow’s angle of tilt for each operational step. The controller then automatically calculates all the other positions from these variables.

This results in movements such as those being described by the arm of the EcoRP E043i in the Bietigheim-Bissingen test center – powerful, yet elegant. Developer Hannig is proud. “The outlines were developed in collaboration with an industrial designer and bear the unmistakable Dürr signature.” Smart technology doesn’t just have to work perfectly – it should also look good.

Jens Häcker und Detlev Hannig

JENS HÄCKER (48), LEFT

Jens Häcker has been working at Dürr since 1995. He was team leader for many years, developing software for the operation of technical systems. Today Jens Häcker is Senior Manager Product Development Control Systems.

DETLEV HANNIG (56), RIGHT

Having studied mechanical engineering, Hannig began his career as an engineer with a machine tool maker. He then joined a manufacturer of special machines, where he was in charge of engineering. Since 2008 he has been Head of Robot Systems and Mechanical Engineering at Dürr.