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Automation Technologies 5/2014

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Automation Technologies 5/2014

previous page 03 The

previous page 03 The manufacturer was able to reduce the component count in the Fusion press by close to 60 % with two cylinders, one containing the image and the other applying the ink. All of these cylinders are driven by Rexroth IndraDrive drives and motors. During changeover, once the color cylinders are exchanged and the press web rethreaded, setting the image registration and impressions is the next step. In the past, this involved time-consuming manual adjustment, deck by deck. Using Rexroth intelligent IndraDrive servo drives, PCMC developed a new setup feature called Print- Sense. The image cylinder and anilox inking cylinder in each deck are brought together to reach “the kiss point” where the image impression will be correct. IndraDrive motor feedback data generated by each cylinder’s drive is captured and used by pre-established algorithms to calculate when the proper feedback setpoint is reached from both drives, eliminating the need for time-consuming initial print setup. Feeding energy back IndraDrive systems set new standards in drive engineering, with intelligent functionality, integrated safety features and regenerative power capabilities. “During setup, we can use the IndraDrive Safe Halt feature while we change the plate; normally we would have to build a brake or lockout mechanism to safely hold the axis in position, adding more parts to the system”, states Dave Wall, Engineering Value Stream Leader for Printing, Coating and Laminating at PCMC. The regenerative drive feature lets the Fusion system capture energy typically wasted when machine axes slow or stop, feeding it back into the system power bus to reduce energy demand. Ensuring highest quality printing To ensure high printing quality, the Rexroth IndraMotion MLC motion logic controller is used to operate and control the tension and registration of the press. The system is suited for synchronizing multi-axis systems up to 64 axes. It features pre-engineered function blocks for winding, registration, tension, and other key settings, open system interfaces such as the Sercos(R) automation bus, and support for IEC 61131-3 function blocks and motion sequences. According to Wall, the MLC helps to complete image registration faster, using an integrated endof-line vision inspection system: “The vision system shows the press operator the image registration at AUTOMATION TECHNOLOGIES 5/2014

Control and drive technology Interview with Peter Lutz We spoke to Peter Lutz, Managing Director Sercos International e.V., at Industrial Automation 2014 in Chicago about the appeal of the North American market, the Sercos multi-vendor demo and the network infrastructure of the future. Video About Company name: Sercos International e.V. Headquarters: Süssen, Germany Membership: More than 90 member companies worldwide Products: Sercos-enabled products for any automation application operator controls; the operator can use the controller to advance/retard a color, or move left/right, to get the registration correct.” Reducing costs For major systems like Fusion, cost control is the result of smart engineering that reduces component counts. To accomplish this goal, PCMC, working with CMA/ Flodyne/Hydradyne, chose Rexroth IndraDyn T frameless motors to drive 11 of the Fusion’s axes. IndraDyn T torque motors are liquid-cooled kit motors consisting of a separate stator and rotor designed for maximum torque applications up to 13,800 Nm. The rotor is mounted directly to the extended journal of the cylinder. The central impression cylinder can be > 80” diameter. In order to hold 0.001” accuracy on a 40” radius, Bosch Rexroth utilizes a 32 million ppr sin/cos feedback device. With Sercos, the position commands to the printing cylinders are synchronized with less than 100 ns of jitter. This, along with the high-bandwidth servo gains that are achieved with direct-drive motors and IndraDrive Advanced control sections, results in accurate print registration that is limited only by mechanical and process influences that are outside the scope of the drive and control system. Doug Anderson, sales engineer from CMA/ Flodyne/Hydradyne, worked with PCMC from the outset to select and size the IndraDyn motors. “One of the strengths that Rexroth offers is its vast array of kit motors,” Anderson said. “We selected one torque motor size for the large impression drum, which needs to stop within 10 to 15 s, and then another size to handle the different widths of the image and color rolls.” Using the torque motors enabled PCMC to reduce the Fusion’s part count by nearly 60 % compared to the previous generation machine. Critical rigidity A crucial mechanical design challenge on a printing press is the decks mounting the image and inking rolls. These rolls range in width from 42” to 75”; each deck must move in and out for job changeovers when the press is re-webbed and the rolls exchanged. However, once printing commences, the decks must be extremely rigid and hold the rolls in position, to keep each color layer in perfect registration while the rolls spin up to maximum speed. To provide the flexibility and rigidity needed, each image cylinder and inking cylinder incorporate two Rexroth precision Ball Screws and four profiled Ball Rails. Rexroth Ball Screws and Ball Rails combine high rigidity and load capacity in compact sizes, engineered to deliver precise tolerances and operate error-free with minimal maintenance. AUTOMATION TECHNOLOGIES 5/2014


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