Product category:
Chucks and collets for rotational work
News Release from: Pratt Burnerd International | Subject: Bespoke and standard live and dead centres
Edited by the Manufacturingtalk Editorial
Team on 25 December 2007
Live and dead centres support large
parts
For turning, boring or grinding large rotational pats, a seies of live and dead centres an be selected according to machine rev/min, machine type and accuracy considerations.
Pratt Burnerd International will launch bespoke and standard live and dead centres at the UK's MACH 2008 machine tool exhibition Typically suitable for the oil and energy industries, the centres can be used for any application where large components need to be turned, ground or bored accurately
This article was originally published on Manufacturingtalk on 5 Mar 2002 at 8.00am (UK)
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The range of high quality live and dead centres, which has workpiece capabilities from 125g to 200,000kg, has been designed to meet the demands of precision engineering.
There is a particular emphasis on difficult or heavy machining applications.
The range complements the chucks and workholding systems available from the company.
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Offering a jaw stroke of more than 50mm per jaw, when compared with the typical power chuck of 5mm, a programmable power chuck provides greater versatility and reduction in setting up times.
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Clamping force is controlled through the machine tool's controller in a geared programmable power chuck allowing the safe operating speed can be more than twice that of a conventional chuck.
Designed to give customers the most suitable centre according to application, centres can be selected on the following criteria.
* Required machine rev/min.
* Machine type.
* Workpiece weight.
* Accuracy considerations.
* Shank taper.
* Whether a live or dead centre is required.
The range includes special purpose live centres for applications in spline rolling, medical and lightweight components and workpieces requiring linear compensation.
The standard range incorporates the following.
* High rev/min live and dead centres for precision turning applications.
* Live centres for workpiece weights from 450 to 200,000kg.
* High accuracy live and dead centres.
* Live and dead centres for large bore parts, pipes, tubing and thin-walled workpieces.
Pratt Burnerd told manufacturingtalk.com that its range of live and dead centres is distinguished from competing products by its use of high quality, exclusively configured bearings.
These bearings ensure the highest precision in performance and greatest longevity.
Specialists in the science of rotational workholding - evidenced by the extensive range of specialist precision chucks the company designs and manufactures - the design incorporates multiple bearings to spread the load along the full length of the taper.
* Maintaining accuracy - bearing bores are ground concentric and coaxial to the taper in one operation to within +2.5 micron TIR (total indicated run-out).
This ensures maximum bearing life and accuracy.
Through precisely calculated fulcrum positioning, the full spindle length maintains maximum rigidity, dampens vibration and flexes rather than breaks when subjected to severe loads, crucial in heavy duty applications.
Complementing the novel bearing configuration to give assured precision and maximum rigidity in performance, each bearing shoulder is held to within +2.5 micron TIR perpendicular to the centreline of the shank, conforming to strict DIN standards.
Accuracy of the centres is further enhanced by the gaugeline, cross section and robust spindle construction, designed to produce exceptional resistance to deflection, said Pratt Burnerd.
The threaded seal retainer allows easy bearing access and is lapped to be parallel to the bearing face.
This ensures that the seal adaptor makes complete contact with the face of the bearing for consistent accuracy and rigidity.
Points are hard-turned to 61-63 HRc and bodies are heat treated for extra strength.
Live and dead centres have their accuracies of up to 0.005mm guaranteed.
The range includes centres rated up to 12,000 rev/min, such as for hard turning applications.
Heavy duty centres, for exceptionally heavy workpieces, are of a four-bearing design to ensure radial pressure, thrust and rigidity requirements.
Knockout ends on carbide tipped dead centres are hardened to reduce wear and friction.
* For special use - special application centres available from within the standard range include, for example, the multi-use live centre designed for general machine shop use, where the centre needs to be changed with the job, and are ideal for thin walled workpieces or general shaft work applications.
Bull nose centres, for larger workpieces, are constructed with larger bearings.
The strength and alignment of the fully supported bull nose gives longer centre life.
The Concentric spring loaded live centre is designed with a streamlined low profile, less overhang, added load capacity, and increased rigidity.
The spring loaded spindle compensates for workpiece expansion or contraction.
Director/general Manager of Pratt Burnerd, David Tucker, said: "Our task is to provide solutions to workholding problems".
"Adding bespoke and standard live and dead centres to our range ensures that, whatever the application, we can provide a suitable workholding mechanism.".
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