Heavy-duty machining poses special challenges for processing machines in terms of stiffness, robustness and usually also in terms of the size of machines. The recently built large-scale portal milling machines by Rottler-Maschinenbau are an impressive example for this, utilising large-scale angular heads by ROMAI for certain machining tasks.
ROMAI in Vaihingen/Enz has been developing transmission gears in the form of driven tools, angular heads and multi-spindle heads for 60 years. One of the special strengths of the family business is the production of application-specific special solutions. “Since the tried-and-tested KÜMA product range has been produced and further developed by us, this also includes more and more machining heads for large-scale processing machines - stiff, angular, or with added integrated NC axes,“ explains Mathias Maier, General Manager at ROMAI. The heads with swivel axis which we have recently delivered for the large-scale portal milling machines of Rottler Werkzeugmaschinen GmbH are an impressive example for the huge dimensions.
The large-scale portal milling machines from Rottler are designed specifically for the customer for heavy-duty machining. Ulrich Krause, Authorised Signatory at Rottler Maschinenbau explains the gigantic dimensions: “The portal milling machines have a portal of 3,700 mm and the portal, driven by four engines overall, covers its 21 metres of travel on the X-axis on hydrostatic guides.” Rottler-Maschinenbau relies on complex technology, which does not exploit the machine bed as an oil return channel. Therefore, there cannot be any contamination of the hydrostatics oil with cooling lubricant. Another speciality is that the classic gantry design has been perfected and built with the X-axis at the bottom, which improves the accessibility of the floor plate. The two supports on a fixed crossbeam, which is the Y-axis, stand out with this individually-customized design and enable simultaneous processing. “Feed forces are at 150 kN here, and maximum torque is at 9,500 Nm with a possible 110 kW at every spindle,” Krause explains the utilisation in heavy-duty machining.
As additional components for certain processes, the portal machines are equipped with transmission heads from ROMAI, which can be put into the vertical ram fully-automatically. With a weight of around 1,600 kg and a length of 750 mm overall, its dimensions are also impressive. The housing of the angular head has an additional pivoting spindle housing on the output side, which has a 90° angle. This is interlocking and indexable every 2.5° via axial clamping through Hirth joints or alternatively adjustable with axial clamping in every position. Adapted to designated processes, the transmission heads have a transmission ratio of 1:1.5 at 2,000 rpm.