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.
Friday, June 16, 2006
Transmissions supplier installs 21 CNC lathes
First-tier automotive supplier has, since 1998, installed 21 UK-built lathes for hard- and soft-turning of transmission components and a further three machines are ready.
Almost every day there are gloomy reports of a declining manufacturing base in Britain, but there is still some good news, even in large volume production which is supposedly being lost to low-wage countries. For example, first-tier automotive supplier, GKN Driveline, Birmingham, has since 1998 installed 21 UK-built lathes from the MHP division of Geo Kingsbury Machine Tools for hard- and soft-turning of transmission components. A further three machines are ready for pass-off at Geo Kingsbury's Gosport factory.
In addition, a robotically loaded MHP50 CNC lathe is currently in build, due for installation at GKN Driveline in October 2005, for hard turning critical features on the constant velocity joint, or bell, that forms part of front-wheel and four-wheel driveshafts.
There are already five robot-fed MHP machines on the Birmingham site being used for similar work, each teamed with other machinery including hardening, spline rolling, washing plant to form automated manufacturing cells for outer race constant velocity bells.
Production rate is 1,400 components per cell per shift with five operators.
Each automated MHP lathe is fitted with its ABB robot at Geo Kingsbury's Gosport factory and is supplied, after pass-off, to GKN Driveline as a turnkey package, complete with programs.
The other MHP lathes are in manually loaded cells for soft turning operations on bells and tulips, the latter forming part of the plunging joint in a driveshaft nearer to the gearbox.
Mike Poyner, the engineer responsible for project managing the new production cells at the Birmingham factory, said, 'It is our policy to replace as many grinders as possible with hard turning'.
'Each time a lathe is installed it replaces pairs of external, angle-approach grinders'.
'By doing this, there is a six-fold saving in capital investment, amounting to several hundred thousand pounds''.
''Additionally, it takes two hours to change over an external grinder for a new batch compared to 10 minutes for a lathe, so production downtime is less by a factor of 12.' Driving the original change from grinding to hard turning were difficulties with grinding the hub support diameter of the bell and more particularly a shoulder called the back location face, both of which are pre-hardened to 58-62HRC.
The main problem used to be cracking of the location face during grinding, caused by overheating owing to difficulty in projecting sufficient coolant between the grinding wheel and the vertical face.
The earlier grinding operation and the dry hard-turning sequence that has replaced it includes in-cycle machining of a third OD in an unhardened state of 45-48HRC, namely a seating diameter for an ABS pulse ring.
As all turned features need to be concentric with six internal ball tracks, drawing tolerances are tight: +/-0.013mm for the hub support diameter and +/-0.015mm for the ABS diameter, surface finish for both being 1.6 micron.
As regards the back face, 0.15mm of material is machined away to leave a 0.8 micron surface finish.
The Ra figures achieved in practice are significantly lower than these.
Process capability achieved is Cpk 3.66 for the hub support diameter and Cpk 2.65 for the ABS diameter - significantly better than the required Cpk of 1.67 (5 Sigma).
More recently, GKN Driveline has been working in conjunction with Geo Kingsbury to identify inserts for soft turning that would last longer and reduce cycle times.
When machining a bell in its soft state, the incumbent supplier's insert used to result in a 65s turning cycle and it lasted for 70 components.
After research and subsequent trials, a Kennametal insert reduced the cycle to 55s and was found to machine nearly three times as many parts before it needed replacing.
Poyner described the improvement as a 'step change'.
Almost every day there are gloomy reports of a declining manufacturing base in Britain, but there is still some good news, even in large volume production which is supposedly being lost to low-wage countries. For example, first-tier automotive supplier, GKN Driveline, Birmingham, has since 1998 installed 21 UK-built lathes from the MHP division of Geo Kingsbury Machine Tools for hard- and soft-turning of transmission components. A further three machines are ready for pass-off at Geo Kingsbury's Gosport factory.
In addition, a robotically loaded MHP50 CNC lathe is currently in build, due for installation at GKN Driveline in October 2005, for hard turning critical features on the constant velocity joint, or bell, that forms part of front-wheel and four-wheel driveshafts.
There are already five robot-fed MHP machines on the Birmingham site being used for similar work, each teamed with other machinery including hardening, spline rolling, washing plant to form automated manufacturing cells for outer race constant velocity bells.
Production rate is 1,400 components per cell per shift with five operators.
Each automated MHP lathe is fitted with its ABB robot at Geo Kingsbury's Gosport factory and is supplied, after pass-off, to GKN Driveline as a turnkey package, complete with programs.
The other MHP lathes are in manually loaded cells for soft turning operations on bells and tulips, the latter forming part of the plunging joint in a driveshaft nearer to the gearbox.
Mike Poyner, the engineer responsible for project managing the new production cells at the Birmingham factory, said, 'It is our policy to replace as many grinders as possible with hard turning'.
'Each time a lathe is installed it replaces pairs of external, angle-approach grinders'.
'By doing this, there is a six-fold saving in capital investment, amounting to several hundred thousand pounds''.
''Additionally, it takes two hours to change over an external grinder for a new batch compared to 10 minutes for a lathe, so production downtime is less by a factor of 12.' Driving the original change from grinding to hard turning were difficulties with grinding the hub support diameter of the bell and more particularly a shoulder called the back location face, both of which are pre-hardened to 58-62HRC.
The main problem used to be cracking of the location face during grinding, caused by overheating owing to difficulty in projecting sufficient coolant between the grinding wheel and the vertical face.
The earlier grinding operation and the dry hard-turning sequence that has replaced it includes in-cycle machining of a third OD in an unhardened state of 45-48HRC, namely a seating diameter for an ABS pulse ring.
As all turned features need to be concentric with six internal ball tracks, drawing tolerances are tight: +/-0.013mm for the hub support diameter and +/-0.015mm for the ABS diameter, surface finish for both being 1.6 micron.
As regards the back face, 0.15mm of material is machined away to leave a 0.8 micron surface finish.
The Ra figures achieved in practice are significantly lower than these.
Process capability achieved is Cpk 3.66 for the hub support diameter and Cpk 2.65 for the ABS diameter - significantly better than the required Cpk of 1.67 (5 Sigma).
More recently, GKN Driveline has been working in conjunction with Geo Kingsbury to identify inserts for soft turning that would last longer and reduce cycle times.
When machining a bell in its soft state, the incumbent supplier's insert used to result in a 65s turning cycle and it lasted for 70 components.
After research and subsequent trials, a Kennametal insert reduced the cycle to 55s and was found to machine nearly three times as many parts before it needed replacing.
Poyner described the improvement as a 'step change'.
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