Solid base on which to turn one-offs

Colchester has combined the stability of a solid base and an advanced control and software package into the Combi K-Series CNC lathe for one-off components or batch production.
By combining the stability of a solid base, a 30 deg cast iron slant bed and one of the most advanced control and software packages available for one-off components or batch production, Colchester Lathe's Combi K-Series of CNC turning machines redefine the advantages of simplicity of operation, power and accuracy in a turning machine. Developed specifically for the workshop, toolroom, jobshop and lower quantity batchwork, Combi is now available in K2, K3 and K4 versions which depict capacity and power. In addition across the range, a wide array of options allows the user to specify a machine for general or specific requirements.

For instance, a choice is available of chucks, steadies and tailstock that runs on independent ways, quick-change tool posts or 8-station auto-indexing Duplomatic turrets.

The Combi K2 has a swing over bed of 400mm, X-axis travel of 220mm and up to 1,270mm between centres while the mid-range K3 increases swing to 460mm, X-axis to 290mm and introduces a choice of between centres dimensions of 1016 mm, 1524 mm and 2032 mm.

For the K4 its larger 554mm swing is complemented with X-axis and between centres the same as K3 but with an additional capacity for between centres of 3168mm.

With machining capacity of this order, stability is critical to achieve high performance.

Combi's engineered concrete fill for the base creates an equilibrium within the structure giving the turning process the basic advantage of consistency even when using higher feed rates and greater depth of cut.

In addition, improved surface finish and consistent tolerance machining from part to part can be readily achieved.

Mounted on the base is a cast iron bed giving a 30 deg slant bed configuration which has been patented by Colchester based on its accessibility for operation.

It also creates a low centre of gravity and new levels of freedom for swarf evacuation from the cutting zone.

The machine saddle and cross-slide assembly uses a triple bearing configuration utilising two linear rails at the front and one at the rear which eliminates any tendency for the saddle to 'crab' and the ballscrew drive is mounted in board of the rails.

This design ensures accuracy and stability are maintained under cut and accommodates the 98 per cent increase in Z-axis thrust available with the new K-Series over the previous machine design.

The guide rail also bridges the bed gap via a further patented design.

The single piece cast headstock fitted with Gamet precision taper roller bearings uses a two-stage ZF clutch/pulley arrangement between the 11kW, 15kW and 22kW GE Fanuc Alpha main spindle motors fitted respectively to the K2, K3 and K4 variants.

The Colchester design of spindle drive gives a 20:1 constant power band ratio for high torque turning at low revolutions.

This is best illustrated with the K4 which can provide a massive 1,900Nm of torque at just 112 revs/min.

In keeping with the target users of Combi, Colchester Lathe has developed the Fanuc 210-TA digital control and Windows 95TM format software around Visual Basic.

The on-screen, icon-driven CAM-based system gives a real time virtual tool display while having full compatibility with other Fanuc G-code based programs.

The open-CNC control software can be programmed by six different methods from a simple digital read-out, through on-screen CAM and electronic handwheel teach and repeat, cut and paste, traditional G-code and by direct numerical control download.

The 960 capacity tool library also utilises icon identification and visual recognition of the tool shape and carries the respective geometric tool data with feed and speed information which can be overridden by the operator.

Rescaling of the tool active zone helps detail viewing of the operation which is a critical function when working on intricate or internal features and a wide selection of macros speed the operator through his setting task.

With new design of slide-aside guarding, access is excellent while large viewing windows coupled with high integrity interlocks and a sliding operator panel means the Colchester Combi introduces new levels of ergonomic operation.