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Shop Gains Control

Dec. 21, 2007
Over converter production
A Siemens control and operator panel oversee a Twinmaster roll-forming and laserwelding system at Eberspaecher.

For its new automotive catalytic converter production line, Eberspaecher N.A., a Tier One supplier based in Brighton, Mich., decided to install a laser-welding short-tube production cell instead of a conventional tube mill.

At the heart of the system is a Twinmaster roll-forming and laserwelding production system supplied by Weil Engineering North America of Troy, Mich., a subsidiary of Weil Engineering GmbH out of Muellheim, Germany.

The Twinmaster combines two major functions in one machine: roll-forming and welding. Secondary processes such as blank feeding and post-welding expansion of tubes for perfect roundness are linked directly to the Twinmaster to create a complete production center. A Siemens ( Sinumerik 840D CNC handles CNC operations, and a Siemens Simatic OP170 operator panel provides dialog functions.

The Sinumerik 840D monitors, operates and controls the sequences of operations, the exact timing of each process and all movements. It also monitors the position, power and the on/off condition of the laser beam as well as all the transfer mechanisms and tooling.

“The open architecture and substantial power of the CNC make it possible to easily monitor and control all the various functions. We also produce our own HMI protocols for the CNC and PLC on the operator panel, and the Siemens system makes this much easier to accomplish,” Matthias Philipp, Weil Engineering’s service manager, said.

Onboard the Twinmaster, the Siemens CNC technology controls eight rotary axes, with a Siemens Simodrive 611U drive package on the destacker and chamfering device. Another 611U operates four axes on the expander and handling system.

Using the Profibus field bus system pioneered by Siemens, all CNC, PLC, HMI and drive systems communicate in a more reliable fashion. This lets machine builders such as Weil Engineering adapt CNC programs and modify their controls based on the particular functionalities of their equipment. In this case, for example, two analog outputs are used for power and sequencing to control ramping, on/off and other parameters of the laser. The Trumpf laser on the Twinmaster machine has a 200-mm optics bifocal mirror with a constant focal length. When the material thickness changes, the CNC tooling varies the position of the workpiece.

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