The program is controlled by the CNC software, which allows the operator to have full control of speeds & feeds which can be adjusted without alteration to the finished shape, and thus improving surface finish and size control.

BSA Machine Tools offer machines with "PRO-ELIP" for turning parts such as pistons, cam worm threads and components with eccentric features.  "PRO-ELIP" is fully under the control of the CNC,

PRO-ELIP Elliptical Turning

Components having "OUT OF ROUND" features have in the past been a time consuming process having to be produced on copy type lathes using rotating templates. BSA Machine Tools for the past decade has been in the forefront of development, of "OUT OF ROUND" Turning which is requisite in the manufacture of automotive & marine pistons, heavy duty automotive steering gear, rock drilling coupling thread forms and ballscrews.

Single Pass - Threading of Drill Bits

PRO-ELIP is a full CNC version, with a high performance CNC Slide which follows a form detailed by a data table in the CNC control, where the displacement of the "X" axis is in strict relationship to the angular relationship of the spindle.

For a thread type form only a simple table of one revolution of the spindle is required, with the helixing being provided by another axis. With elliptical piston turning with the piston having a totally variable geometry down its length then a full table containing up to 65,000 discrete points can be programmed. The system can be applied to ANY SHAPE or type of component, limited only by the dynamics of the system which allows up to 3G of acceleration, and the geometry of the tooling.

Rock Bits & Couplings

Rock Bit & Coupling manufacture are typical components that benefit from “PRO-ELIP” when fitted to a Churchill Omega CNC Turning Centre. The machine can be manually loaded or as part of an automated set up with In Process Gauging, and Gantry loading to from a carousel material Feeder

Feathered Edge

A feathered edge is the sharp edge at the start of a thread that results from the thread flank cutting into the component nose angle, and at the end of the thread where the flank angle breaks out into the recess entrance angle.

The “PRO-ELIP” process removes this by creating a shape equal and opposite to that which creates the thread form, and adding the two shapes together.

Initially by applying a shape that is fully equal & opposite, one cancels the other out, but by gradually changing the proportion of the additional negative shape, the original positive shape is affected, until eventually the additional shape is equal to zero, thus not affecting the original shape. The gradual change of shape occurs over a number of revs at both the start & end of the thread, producing a clean feathered edge.

Piston Turning

The example shown is manufactured in cast iron. The component 160mm in diameter, and 280mm long consists of a varying elliptical form along its longitudinal stroke, with a second eccentric form which has to remain constant and in synchronisation with the pistons ovality.