The German machine tool manufacturer SHW Werkzeugmaschinen — located in Aalen, near Stuttgart — has introduced a trio of portal machining centres with gantry drive for the production of large high-accuracy components. Called PowerBridge, they are available in the UK through Geo Kingsbury Machine Tools Ltd, Gosport (www.gkholdings.com).

Featuring a new dynamic tool-changer that exchanges HSK A 100 tools (or similar) while machining is in progress, the PowerBridge also has an operator platform/cabin that can travel with the spindle into the working area.

Other highlights include automatic milling-head replacement, liquid-cooled drives and the possibility to integrate turning by fitting a 250rev/min rotary table with torque drive.

During tool change, the next cutter is not picked up by the spindle from the magazine but is transported by a five-axis robot to the spindle, no matter where it is located. The robot is synchronised with the bridge and the tool is transferred synchronously to a tool-changer fork, thereby minimising spindle idle time.

The mechanism can supply tools to two separate bridges.
In the travelling control cabin, the operator is at the same height as the spindle and has a good view of the machining cycle as it progresses.

Alternatively, the cabin can be parked at any position along the longitudinal axis in the work area (for example, to avoid a potential collision).

The machining centres feature a modular design that is shared with SHW’s travelling-column machines; they also use similar components for other key elements, including
the bridge, milling head and rack-and-pinion drive.

The three models have widths of 3,100, 4,100 and 5,100mm respectively; the bed lengths range from 10 to 50m, and the Z-axis travel is 1,800mm. Control is via a Siemens 840 DSL.

A laser tracking system that continuously measures and compensates for axis errors during machining is currently being developed.