Re-manufactured VTLs are very competitive

Machine tool company is putting more investment into re-manufactured VTL's - having acuired more 'carcasses' to offer competitive CNC vertical borers to the aerospace and turbine industry

To find competitive CNC vertical borer solutions for the demands of the aerospace and turbine industry, Pennine has expanded its 'VTL Re-Engineering' programme with the addition of seven vertical turning lathe (VTL) carcasses for its 2006 programme.

The seven machines are, three Morando VLN-12, two Schiess DE14 and two Schiess DE18 models.

The Morando type VLN-12 machines are elevating rail, ram machines with 1200mm tables (1600mm swing) and 12 station toolchangers.

Schiess DE 14 machines are elevating rail turret machines with 1250mm tables (swing 1400mm).

The Schiess DE18 are elevating rail turret machines with 1600mm tables (swing 1800mm).

All will be supplied with new CNC controls and drive systems (Fanuc) although a particular customer requirement maybe possible.

The re-manufactured stock build programme takes sound machine carcasses, which are subsequently rebuilt, re-engineered and retrofit with the latest CNC technology.

Result is large capacity, sturdy accurate machines at a reduced cost (compared with new) having as new accuracy and performance.

These machines are then sold with full warranty John Ginley, Pennine's managing director, explains, "Typical parts which are produced on these VTLs are large rings with complex profiles to tight tolerances from exotic materials, such as titanium and nimonic alloys.

A significant priority is placed on accuracy, machine rigidity and high torque and power at relatively low cutting feeds and speeds.

Re-manufacturing and Re-engineering a sturdy carcass machine, such as the Schiess and Morando variants, provides an excellent base to achieve these priorities.

A re-manufacturing and re-engineering programme starts with a complete assessment of the machine condition, followed by dismantling of the machine for examination, logging and a quality audit of all the major sub assemblies.

At this stage, depending on the examination results, a decision is taken on which aspects of the machine will be retained and which will be re-engineered." Typical areas that maybe re-engineered are: * Replace the existing axis drive arrangement with the latest digital servo motors, coupled to the ballscrews through torsionally rigid couplings or timing belt drives, to improve positioning response and reduce backlash.

* Replace an existing multi-speed table drive gearbox and fixed speed motor with a 2 speed electric change unit and modern digital spindle motor.

This gives infinitely variable speeds, a better power profile, less noise, less driveline backlash and allows the use of constant surface speed control.

* Fit a table encoder to provide screw cutting and feed per rev operation.

* Replace the axis lubrication system (pump, distributors, piping, etc.) and enhance monitoring to aid precise positioning and to minimise wear.

* Replace the original hydraulic installation with a new compact system to reduce oil capacity, lower power consumption and allow greater monitoring (levels, pressures etc).

The more compact tank can often be fixed to the machine carcass, removing the need to disconnect the hydraulics when the machine is moved.

f* Fit an enhanced guarding system to meet current health and safety requirements and provide improved coolant and swarf control.

The guarding arrangement can accommodate a swarf conveyor if required.

* Replace existing wiring with new to meet CE requirements.

* Select a new CNC control to suit machine type with digital control, to provide latest features at the machine and with enhanced communication capabilities to allow connection to customer networks.

* Add direct axis measurement, particular to the X (diameter) axis, for enhanced accuracy and improved repeatability.

j* Upgrade the toolholding arrangement to incorporate modern systems, such as Sandvik's Capto.

k* Take advantage of modern compact electrical and electronic equipment to reduce the size of the electrical panels.

Where possible these are mounted on the machine carcass to ease maintenance, reduce floor space, remove the need to disconnect the machine when moving and provide a single machine lift.

* Decide on operator station type and position to provide flexible viewing and operation available with new compact CNC controls.

Fixed or portable handwheel arrangements can be incorporated to aid machine setting.

* Consider the fitment of tool setting and/or workpiece inspection probing systems.

The same care and attention to detail is applied to the elements of the machine that are being retained.

* After a thorough cleaning of all parts, the slideways are inspected and re-ground as necessary.

PTFE-based anti-friction material is fitted to the moving elements to reduce stiction and aid positioning accuracy and repeatability and/or linear bearings replaced or refurbished to return the machine alignments to British Standards for vertical CNC borers.

* Gearboxes (eg elevating rail and retained table drive components) are stripped and all bearings and any worn gearing replaced.

* Table bearings are inspected and, if required, replaced with new.

* The table bearing and gearbox lubrication system is overhauled and, where possible, improved and then checked for correct operation.

* Tool holding systems (turrets or toolchangers) are completely overhauled.

f* Ballscrews are refurbished or, if necessary, replaced with new.

New support bearings are fitted.

* Telescopic steel slideway covers are refurbished, with the fibre bellows type being replaced with steel telescopic units.

* The machine's moving elements are precisely aligned and adjusted using calibrated granite artifacts, and finally checked with Pennine's Renishaw laser interferometer.

* The re-assembled machine is now rewired using appropriate wiring, conduits and drag-chains and with due regard to CE requirements.

* Sensors and solenoid valves on the machine are wired directly to the CNC's distributed I/O, which allows a comprehensive software interface to be written to control the machine and provide the necessary safety interlocking and enhanced diagnostic support.

* In addition to cable routing meeting new CE requirements, the latest cabling, tubing and drag-chains provide a more modern appearance.

* Finally, a suitable enclosed and interlocked guarding system is designed, manufactured and fitted.

At the end of the Pennine re-manufacturing process, the machines are ready to meet the customer's 2006 production demands.