By combining a twin spindle lathe configuration and two 12-station tool turrets (all positions live) with a separate, toolchanger-equipped, high power milling / drilling head that acts at either turning spindle, the new Nakamura Tome STW 40 offers unrivalled flexibility for complete machining of complicated components in a single set-up. Mills Manufacturing Services is UK agent for the Japanese machine builder which believes this configuration to be a world first. It eliminates many of the limitations experienced with mill-turning technology by combining all the advantages of a dual-opposed-spindle lathe with machining centre levels of milling and drilling capability and power.
The key element of the design is the dedicated milling spindle.
This is sited above the turning spindle centreline on its own set of slides so it can access either headstock.
The milling facility has three linear axes of movement afforded by the Z-axis slides (1600mm), X-axis saddle (620mm) and independent Y-axis (+110 mm / -90mm).
In addition, a B1-axis is provided for +/-100 degree indexable rotary positioning of the milling spindle in 0.001 degree increments.
A built-in motor drive provides 15kW of power and speeds up to 6,000 rpm, with a 12,000 rpm option.
Through-tool coolant is available.
Either Capto or KM toolholders may be specified, while the standard tool magazine accommodates 40 tools; 80 and 120 tools are optional.
Maximum tool dimensions are 120mm diameter by 250mm in length and exchange time is 1.5 seconds for adjacent pockets.
Both turning spindles have C-axis control in 0.001 degree increments and are powered by identical 22 kW built-in motors offering speeds up to 3,500 rpm.
Two spindle specifications are available with bar capacities of 71 mm or 88mm.
Maximum speed reduces to 2,500 rpm for the larger spindle option.
The right hand spindle is mounted on a B2-axis slideway having 1600mm of travel.
Maximum turning diameter is 570mm and turning length is up to 1500 mm.
Dedicated 12-station turrets with powered tooling are provided for each turning spindle.
The turrets are mounted on a common slideway and each has 275mm of X-axis stroke.
Z-axis travel for both turrets is 550mm.
There is also a single turret version of the machine, in which case the Z-axis travel is 1530mm.
Turret-mounted rotary tools benefit from a 5.5kW motor drive at speeds in the range 27 to 3,600 rpm.
Linear axis rapid traverse speeds are 25m/min in X, 20m/min in Y and 30m/min in Z and B2.
Rotary axis speeds are 400 rpm for the C-axis and 12.5 rpm for the B1 axis.
A variety of machining options is available including gantry load / unload and high pressure coolant.
Tool setting and probing for workpiece measuring may be included in the system.
With 11-axis simultaneous control, the machine offers an almost limitless range of machining possibilities.
It is possible to carry out complex machining operations on both spindles simultaneously so the opportunity exists to completely machine any component that fits into the work envelope.
Control is by a customised version of the Fanuc 16I-TA CNC system which can be supplied with a variety of software options including a shop floor-based, high level programming system, the NT Nurse monitoring system and the NT Work Navigator which provides a high level of cycle automation.