Until now, the manufacture of large wormgears has taken advantage of the specialist skills and knowledge of the operator, enhanced by each operator’s personal familiarity with his or her gear hobbing machine, which over time will develop special and unique characteristics.
Consequently, the production of large gearsets has traditionally required time-consuming design procedures, followed by a complicated series of machining processes – including the cutting of the wormwheel and grinding of the worm thread prior to meshing. In rare cases, this has been followed by the regrinding or recutting of the worm or wheel in order to achieve the desired contact.
Holroyd has conducted research into practical ways to combat the disadvantages inherent in traditional design and production methods and the reliance of these methods upon a declining number of skilled gearcutters and ageing machines.
As well as investing in the refurbishment of these machines, the company has been instrumental in the development of a Wormgear Contact Analysis Program capable of predicting wormgear contact between worm and wheel, given pre-determined design parameters and known application characteristics.
Four years in the making, the program has been proven with hundreds of hours of theoretical, synthesised (accounting for known machine errors) and actual marking patterns, logged on wormwheel sizes from 3’/76.2mm to 33’/838.2mm.
Holroyd’s Wormgear Contact Analysis Program can predict contact movement affected by worm/wheel distortion or centre line/ centre distance misalignment as well as delivering approximately 95% mirror image between predicted and actual marking patterns.
This enables Holroyd to use information regarding the predicted worm/wheel distortion imposed by a given load, to cut wormgears off-load, whose contact pattern will automatically compensate for the distortion imposed by the load to which the gears will be subjected during use.
‘The beauty of the Wormgear Contact Analysis Program is that it now represents an integral part of the wormgear design process and is no longer used solely as a retrospective tool for correcting inaccuracies,’ explains Steve Whitehead Holroyd Sales Director (Gears).
‘As a mark of our confidence in the Wormgear Contact Analysis Program, we’re inviting wormgear users to present us with their manufacturing challenges, to which we will provide a predicted solution model absolutely free of charge!’