Friday, February 23, 2007

Spindle design quality boosts turning accuracy

Performing machining trials over 30 components from 42mm diameter brass bar, the latest turning centre maintained a size tolerance within 3.5 microns, qualifying the quality of the spindle design.

Performing machining trials over 30 components from 42mm diameter brass bar, the latest Hyundai Super Kia SKT 15 turning centre maintained a size tolerance within 3.5 microns. In further machining trials over a series of 30 mm diameter aluminium parts, a roundness of 0.5 microns was achieved, qualifying the quality of the spindle design, and machine build with the repeatability available from the closed-loop measuring system employed. The new Super Kia machines designated under the 15/21 Series is now available from C Dugard of Hove in Sussex, UK, and can be specified in two-axis bar and chucking formats, with options to upgrade the specification to include subspindle and driven tooling.

Bar capacities are 44mm for the SKT 15 and 66mm diameter for the larger SKT 21.

On the larger machine, swing over cross slide is 350mm and maximum turning length is 410mm.

Hyundai-Kia is, by some significant margin, the largest builder of machine tools in Korea and has developed the SKT to provide higher accuracy and short cycling over a wide range of components.

Constructed on an exceptionally rigid single cast iron bed, it carries a three piece coupling designed turret with hydraulic clamping and a thermally symmetrical headstock with direct drive spindle.

Both the spindle with 11kW or 15kW motor giving 6,000 or 4,000 rev/min respectively and axis drives to the 12 station turret, have been specified for fast acceleration to minimise non-cutting times with the spindle able to accelerate to 6,000 rev/min in 2.2s and the rapid traverse from zero to 36m/min in 0.1s.

Both the SKT 15 and SKT 21 have a wide range of options such as driven tools for every turret station and a C-axis.

Tools are powered by a 3.7kW, 4,000 rev/min motor giving a drilling and end milling capacity of 20mm and M 16 for tapping.

When the subspindle is specified for 'one-hit' production cycles the chuck size is 135mm and is powered by a 3.7kW, 6,000 rev/min motor.

Indexing at 5 increments can also be added to cater for more complex work.

Rapid traverse of the subspindle is 30m/min for quick automatic part transfer from the main spindle.

A parts-catcher is optional to service both the main spindle or subspindle.

A one-touch tailstock is available having a 9s positioning time at 3 m/min rapid traverse rate.

Clamping and unclamping is automatic and the retraction rate is doubled to 6m/min to reduce lost cycle time.

Quick-change chuck jaws that can be exchanged within one minute are optional and a Q-Setter is standard to enable tool offsets to be automatically captured.