TPT July 2007

S traightening & F inishing T echnology

After the introduction of high-speed CNC tube bending machines the demands of the industry changed. Furniture makers now demanded very good straightness so that the loading and feeding stations could feed the tube into the CNC bender at high speed and without any misfeed or tube jams. Although 6-roll straightening machines have their niche, today, the 10-roll machine is now the standard. Automotive prop shaft tubing, steel or aluminium is the preserve of the 10-roll, computer controlled straightening machine. With 5 pairs of

vertically opposed rolls, the outgoing tube is corrected to less than 0.001" TIR (0.025mm) with exacting straightness. The difficulty in setting 10-roll machines initiated the development of computer setting systems in the late 1980s. These systems store all the required data to reset the machine for a specific tube. This stored data is used to control motorised roll positioning equipment to reset the machine for a new size of tube in less than a minute. The majority of 6 and 10 roll machines are now shipped with these systems.

Small batch production with many size changes per shift is now possible with consistent quality. In addition to providing better tube straightness and ovality, the 10-roll machine produces a considerable increase in straightening consistency. This increase in consistency is clear when processing badly bent tubes. It is a function of the additional number of plastic cyclic deflections that occur within this type of machine. The 10-roll machine is clearly more flexible, being able to apply a large bending moment at the first pair of deflecting rolls, which is then linearly reduced to apply a finishing action at the last pair of deflecting rolls. The leading end and trailing tube ends are straightened more effectively due to the ability of the machine to apply additional pressure straightening between 5 pairs (10 roll) rather than 3 pairs (6 roll) of rolls. Turner Machine Company Inc – USA Fax : +1 330 332 5871 Email : turnermachine@turnermachineco.com Website : www.turnermachineco.com

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fi Computer setting systems ensure more accurate roll positioning

Computer setting systems provide more accurate roll positioning and ensure that each operator sets the machine with recorded and well- established roll positions. Tube quality is maintained from batch to batch due to setting the rolls to the same positions that were used to run the machine when that specific tube size was last produced.

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J uly /A ugust 2007