Cutting tool giant Sandvik officially opened its Global Application Centre for Deep Hole Machining, in Cirencester, on Friday, 21 May 2010. The setting up of this operation follows the acquisition by Sandvik, in 2008, of deep hole machining specialist BT Heller Drilling Systems.
In its new demonstration area, the company put on a show of its capabilities.
The production of such chambers is not new, but the demands for this particular example were, with the solution shown just 6 months old, as at the official opening of the Cirencester facility.The demands included the ability to machine the exotic material, so a challenge for tool wear, concentricity and surface finish requirements. The latter meant that support pads that ride (rub) on the machined surface could not be employed.
The demonstration is of a special turning head that features both an expanding/retracting single-point cutting unit and hydraulically operated support pads within a rotating body.
So, the bore is first drilled, then the turning head is fed down the bore; at the appropriate point, an X-axis (coincident with the drilling Z-axis) is used to expand/retract a turning tool to generate the chamber under CNC control; when the turning head requires it, hydraulically-driven support pads spring out from the cutter head, resting on the just-cut surfaces, but are held within a rotating body such that the pads are stationary on the bore surface, rotating with the component.
Additionally, the hydraulic mechanism that drives the pads, which is located behind the drilling spindle, features a linear measuring scale that indicates what the chamber diameter is, allowing for remachining, should that be necessary.
Author: Andrew Allcock