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Machine manufacturer returns to Control Techniques

05 January 2010

A heat exchange machine manufacturer has turned to Control Techniques for Unidrive SP AC drives and Unimotors to provide high-speed servo control throughout one of its machines. The machine is destined for components manufacturer, Denzo Corporation, and will produce radiators for the Italian motor industry.

Fin machine drive panel
Fin machine drive panel

“Control Techniques’ Unidrive SP drives are our standard servo drive,” says electrical manager, Mark Forster. “We find them by far the easiest to commission and program – typically half a day for a system.”

Denzo’s new machine is in two sections. The first section, making fins from aluminium strip features nine Unidrive SP drives. The second, integrating the folded tubes and fins into a core, has a further 15 Unidrive SP drives and a Commander SK AC drive. Most of the Unidrive SP drives are paired with a Unimotor FM servo-motor from Control Techniques.

The fin section starts with aluminium strip from 32 up to 100-mm width, which is fed through a back-tension unit, then through a splitter unit to divide the strip into two and on to form rolls that put the 10-mm louver into the fin to increase the surface area for maximum heat-exchange performance. A gathering station takes the form and gathers it to a tight pitch and onto the pack-up station featuring a scroll-screw to generate the required pitch in peaks per decimetre. An encoder fitted to the last gearbox on the gathering station provides a line-speed reference to which the other drives are digitally locked, with the gathering station being at a ratio more, or less, than the line speed. Finally, a rotary blade cuts the fins to length. Throughout the section, 1.1 kW Unidrive SP drives and Unimotor FM servo-motors precisely control all of the key movements.

Corebuilder machine from fin machine
Corebuilder machine from fin machine

At the start of the corebuilder section, a pick-and-place vacuum system unloads paper-wrapped packs of cut tube into the machine, the paper is spliced and the tubes are tamped into a two storage sections. This involves two pick-and-place processes, one pneumatic, one controlled by Unidrive SP drives with Unimotors. A ‘pecker’ indexing them into position alternately with sections of fin, building up the required number of tubes and fins together, before moving the set forward to the locator area, where blades drop behind and in front of the set to tamp them into place. Airway locators are raised from under the table for receiving tubes and positioning the fin to the correct position from the end of the tube. Side-plates are brought across and dropped into position and the core in centred and moved down the table. This is servo-drive controlled and has to be absolutely precise, with effectively no tolerance. With the core compressed, the tamper plate lowers to position the fins correctly and, at the core assembly section side members are fitted. At the manifold location, a two-piece round tube manifold is positioned onto the core. Use of Unimotors controlled by Unidrive SP drives provide both core compression and header fit, giving absolute accuracy and throughput as well as low maintenance.

The core is now completely built with interference fit of the parts and is moved to the end of the corebuilder section ready for subsequent tunnel brazing.

Unimotor FM installed at fin machine
Unimotor FM installed at fin machine

All of the Unidrive SP AC drives are running in servo-mode and are 1401 models (1.1 kW), mostly paired with small, high-performance Unimotor FM servo-motors. Each drive is fitted with applications modules to give on-board programming and a Devicenet and Profibus module for communications. All of the drives on the corebuilder section are digitally locked, giving tolerances, typically, of 0.1-mm, with the header tooling tolerance even better than this, since any error in positioning can result is a blocked airway, which would means the whole core would be subsequently rejected.

“We work very closely with Control Techniques as we further develop our machines to give even greater outputs,” said Forster. “For example, we are looking into greater use of Ethernet which has the potential to give both faster communications and to allow us to access the machine remotely, in the event of a problem. Our relationship with Control Techniques is excellent and we value the worldwide support that they can provide through their drive centres. Above all, we find Unidrive SP very easy to use, very versatile and ultra-reliable.”


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