Changzhou ChangBao from Changzhou, Jiangsu Province, China, has commissioned a new stretch-reducing mill including automation system from SMS Meer www.sms-meer.com , Germany. The scope of supply includes the CARTA® technology package (Computer Aided Rolling Technology Application) and a fully automated groove dressing machine of type KR III 25 CNC. It will enable Changzhou ChangBao to produce heavy-walled tubes with small diameters from high-alloy steels.

The stretch-reducing mill is equipped with the SMS Meer single universal drive. Each roll shaft is driven individually by an electric motor. By contrast with conventional stretch-reducing mills, the undesirable internal polygonization does not occur here. An internal polygon is a wall thickness irregularity of hexagonal shape that occurs particularly in tubes with large wall thicknesses and small diameters. “With the stretch-reducing mill from SMS Meer we can produce more flexibly and improve the product quality. CARTA® ensures a very good tube quality and uniform wall thicknesses. With the new groove dressing machine, we also have the right groove for every diameter quickly and easily to hand,” says Wang Kui, Technical Director at Changzhou ChangBao.

The mill has an annual capacity of around 100,000 tons of seamless tubes in the diameter range from 26.7 to 114.3 millimeters.

Free groove shaping
Changzhou ChangBao has also received a KR III 25 CNC groove dressing machine from SMS Meer for machining the rolls of the new stretch-reducing mill. The grooves in the rolls can be machined fully automatically on this machine. The machine is equipped with a measuring device which records the stand and roll data under automatic program control. Machining of the rolls from the front side of the stand allows any desired groove form to be produced and the edge radii to be machined in a single pass.

Changes to the groove forms are easily possible by quick repro-gramming of the machine. Linking to the works databases and control systems, for example to the CARTA® technology system from SMS Meer, is also possible. SMS Meer has trained the customer's personnel intensively so that they can operate the machine efficiently.

SMS Siemag