Okuma VTM-1200YB vertical lathe/5-axis hybrid offers single set-up efficiency
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The 30-tonne, double column Okuma VTM-1200YB from NCMT has been designed as a cross between a heavy duty vertical turning and boring facility and a 5-axis machining centre. Structurally, it is configured as a bed-type machining centre, but, instead of a conventional table, it has a 30 kW/500 rpm/6,000 Nm torque turning spindle with 360,000-increment C-axis positioning.
The Okuma VTM-1200YB's table has a pair of large cross section X-axis slideways carrying a substantial column with vertical Z-axis slides. These in turn locate a saddle with Y-axis cross slides to support a 37 kW/10,000 rpm/505 Nm milling spindle (B-axis) with HSK-A 100 taper. By locking it using a Curvic coupling, turning operations on components up to 1,200 mm diameter by 1,080 mm long can be carried out without risk of damaging the bearings.
With 150º B-axis positioning, standard tooling can be used in situations where specials might otherwise have to be considered. In addition, says NCMT, it is possible to improve milling efficiency when using ballnose cutters by using the tool at an angle to avoid zero surface speed cutting at the tip. Similarly, angled holes can be produced without the need for special fixtures using a three-dimensional co-ordinate conversion facility within the control software.
The standard tool magazine houses 60 cutters and a common taper standard is used for both milling and turning. Through-tool coolant is rated at 150 bar for efficient cooling and chip control, especially important when working with tough materials such as titanium and Inconel.
XYZ axis travels are 1,270, 1,080 (vertical) and 1,000 mm respectively. Absoscale linear encoders guarantee 0.1 micron feedback. Rapid traverse rate is 32 m/min in all linear axes, 20 rpm for the 360º C-axis and 19.5 rpm on the B-axis. Control is by Okuma's own OSP-P200 CNC system.
During simultaneous 5-axis milling, tool centre point control and Super-NURBS provides high contour accuracy and surface finish. In combination with Okuma's 'thermo-friendly concept', even if the ambient temperature changes, achieve accuracies better than 10 microns can be achieved, says NCMT.
Options include a pallet change system, allowing the machine to be configured as a semi-automated, stand-alone machining cell.
