Gently does it

Gently does it
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November 2015

 

The FLOWTOS machine made by Winkler+Dünnebier produces as many as 4,600 paper tissues a minute. Bosch Rexroth was involved in the development of the latest generation of the machines – from the planning stages through to market introduction.

The objectives that Winkler+Dünnebier (W+D) set for themselves when developing a new paper tissue machine were high. The machine was not only to process two-, three- or four-layer tissues at lightning speed but at the same time to package them ready for sale. In addition, the company wanted to use the same automation components for all their manufacturing processes and thus offer a machine “cast in a single mold”. From the very beginning W+D took Bosch Rexroth, with its 20 years of experience in this field, on board for this task. The drive and control specialists contributed to the machine’s development right from the concept stage and continued through to commissioning and marketing.

Electronics instead of mechanical elements

In earlier machine generations toothed belts were used to coordinate movements. This mechanical link made sure that various tools were synchronized, but it did require intricate and time-consuming fine tuning – especially where changes in formats or products were involved. A self-contained configuration manager now performs these adjustments in order to reduce FLOWTOS tool set-up times. It is based on the intelligent IndraDrive Mi servo drives, in combination with the IndraMotion MLC motion logic control. This solution lets the machine to be adjusted by just pressing a button. The machine adapts to the size of the tissues and the number in each packet. These IndraDrive Mi servo drives are cabinet free and work harmoniously, in full compatibility, with conventional servo drives. The latter are housed in control cabinets due to the higher power requirements – to drive the large-scale rollers used to unwind, smooth and emboss the web of material, for instance. A central power supply, located in the control cabinet, supplies the IndraDrive Mi units with direct current. The power supply and the SERCOS fieldbus are contained in a single hybrid cable. This reduces the amount of wiring by up to 90 percent.

Thanks to the electronic motion control the operator can simply enter new products whenever specifications change and continuously optimize processes during production. In the background, the FlexProfile suite of functions automatically adjusts cam movements. “This is much faster and simpler than having to make mechanical adjustments,” says Frank Jungbluth, the system developer responsible for FLOWTOS at W+D. In addition to shortening setup times, W+D also wanted to adopt an open concept to achieve new milestones in machine operation, maintenance and accessibility. This is why the company designed the new FLOWTOS with the rollers attached on one end only – this being made feasible by the servo drive concept with its distributed intelligence. “We wanted use cantilevered rollers exclusively in this machine. This is why we have a rear panel into which the tools and drives can be screwed. This gives the operator of the FLOWTOS unimpeded access to the machine,” explains Jungbluth. This saves time when work is being performed right at the machine.

W+D designed the new FLOWTOS

W+D designed the new FLOWTOS entirely with rollers mounted on one end only, thus making the machine completely accessible to operators. This saves a great deal of time, especially when work has to be done directly at the machine.

 

Keeping your mind free for the essentials

W+D used various Rexroth tools even when laying out the design for the machine. The extensive library of pre-programmed technical functions was especially useful in this respect. Collaborating with Rexroth appealed to Frank Jungbluth because he was able to concentrate entirely on his own processes. This engineering expert mentions in particular the options provided by IndraWorks, which carries out basic actions largely by way of prepared suites of functions. In this way, machines can be adapted by entering simple parameters. “We don’t need to waste time re-inventing the wheel, especially for standard functions,” says Jungbluth.

Since dynamic cams control motions during paper tissue production, the CamBuilder software tool, which is integrated into the engineering suite IndraWorks, was used extensively. It is ideal for graphic programming of complex motions and is easy to use. During the engineering process, the interaction between the axes can be optimized using preview functions. The system developer quite simply, with a single touch, creates the FlexProfile module needed for linking with the motion program. “We really came to appreciate this procedure,” Jungbluth exclaims. “This is because each member of the team was able to concentrate on the actual process solutions and not on how to design the required motion profile. These basic functions are already included as standard in the IndraMotion package and do not have to be purchased separately.”

Drives and controls from Bosch Rexroth support various functions in the FLOWTOS

Drives and controls from Bosch Rexroth support various functions in the FLOWTOS, from grouping the tissues ... through to separating the groups.

 

Support from A to Z

During the entire development phase the Bosch Rexroth application engineers were available to W+D’s staff by phone or video conference, simplifying the engineering process. Rexroth’s mechatronics support section also helped the company through simulations and vibration analyses. The results provided valuable references for developing the mechanical components. Once the preparatory development work had been completed, Bosch Rexroth continued to liaise with the company as necessary during the machine’s commissioning. Joachim Loock, vice-president for engineering of controls and drive technology at W+D, summarizes the entire process: “In retrospect, we jointly implemented a very sophisticated project in perfect fashion. The machine has established itself on the market and several customers around the world are running it in 24/7 operations. We chose the right partner to engineer the automation.”