Wormgear contact analysis reduces errors

Wormgear Contact Analysis program has revolutionized the production of large centre-distance wormgears by reducing error margins and manufacturing leadtimes.
Specialist UK gear manufacturer, Holroyd, has developed a new Wormgear Contact Analysis program that revolutionizes the production of large centre-distance wormgears. The program both reduces the margin for error in the manufacture of precision, made-to-order gearsets and enables dramatic reductions in lead times to be achieved. It also ensures greater consistency in manufacture and longer gear life by providing benefits, such as improved controllable contact spread, smoother unscraped finish, enhanced lubrication and the ability to cut wormgears off-load to offset distortion due to loading during use.

Developed at Holroyd's Rochdale production plant over a four-year period, the analysis program has been proven with hundreds of hours of theoretical, synthesised and actual marking patterns, logged on wormwheel sizes from 3in (76.2mm) to 33in (838.2mm).

In addition to delivering approximately 95% mirror image accuracy between predicted and actual marking patterns, crucially, Holroyd's Wormgear Contact Analysis Program also predicts contact movement, affected by worm/wheel distortion or centre line/centre distance misalignment (see graphics).

This enables Holroyd to use information regarding the predicted worm/wheel distortion imposed by a given load, to cut wormgears off-load, whose carefully calculated contact pattern will automatically compensate for the inevitable distortion imposed by the load to which the gears will be subjected during use.

Stephen Whitehead, Holroyd's Sales Director for Gears, is one of the main driving forces behind the new program.

He explains its significance: 'Historically, the manufacture of large wormgears has taken advantage of the specialist skills and knowledge of skilled gearcutters and their familiarity with gear hobbing machines, which, over time, develop special and unique characteristics'.

'Traditionally therefore, the production of large gearsets has involved a time-consuming and painstaking design procedure, followed by a complicated series of machining processes, including cutting of the wormwheel and grinding of the worm thread prior to meshing, followed, in rare cases, by the regrinding or recutting of the worm or wheel, in order to achieve the desired contact'.

'The introduction of the Wormgear Analysis Program changes this situation fundamentally.

The program functions as an integral part of our wormgear design process, removing the reliance on traditional - and declining - skills-based manufacturing.

It enables us to eliminate trial and error from the design and production process using contact prediction graphics and revised calculations, with the result that we are able to manufacture accurate and efficient gearsets right first time'.

'The fact that we have spent so much time and resources on the development of this program highlights our determination to remain leaders at the very forefront of precision wormgear production technology.

Over the years Holroyd has earned a reputation for creating effective and affordable solutions to even the most problematic wormgear engineering challenges, thriving on an unrivalled ability to realise business opportunities in complex and demanding applications which other manufacturers often find difficult to address.

The Analysis Program further strengthens our abilities in this area, so much so that 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!'