An alternative wheel regenerative mechanism in surface grinding: distributed grit dullness captured by specific energy waves

Máté Tóth,Neil D Sims,David Curtis

doi:10.1016/j.ymssp.2021.107964

Máté Tóth, Neil D Sims + Show 1 more

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https://doi.org/10.1016/j.ymssp.2021.107964

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Abstract

Regenerative chatter is a serious problem in machining. It is an unstable relative vibration between the workpiece and the cutting tool that adversely affects virtually all chip formation processes. This paper addresses regenerative chatter in grinding, which is one of the most widely used abrasive processes today. As a result of significant tool wear in grinding, surface regeneration (which is a prerequisite for regenerative chatter) can occur not only on the workpiece but also on the grinding wheel. This article is concerned with the regenerative mechanism by which wheel-related instability develops.In the present study, the role of distributed grit dullness alone is explored. A new chatter model is formulated and validated by both numerical simulations and experimental data. The new theory accurately predicts the existence of stable regimes in grinding, for the first time. This is in contrast to the published literature where the consensus has been that grinding cannot be stable with respect to wheel regeneration. Consequently, the present contribution enables a novel opportunity to increase the productivity of industrial grinding operations.

Highlights

Grinding is the oldest machining operation [1], and represents 20–25% of the manufacturing sector in developed countries [2]
Due to the fact that the stability boundaries are rather sensitive to low grinding ratios, which varied quite a lot in the experiments, ideally, every test point should be presented with its own set of stability boundaries, which would be an impractical way of summarising the stability results
The authors plot only three sets of stability boundaries corresponding to the minimum, average and maximum grinding ratios, in order to consider the non-negligible variation of this parameter, yet present the results as concisely as possible

Summary

Introduction

Grinding is the oldest machining operation [1], and represents 20–25% of the manufacturing sector in developed countries [2]. The downside of machining with a grinding wheel instead of a conventional cutting tool is excessive tool wear, significant heat generation, and – from a theoretical point of view – the complexity of process modelling and prediction due to the inherent randomness of the wheel geometry [3] This last disadvantage makes it especially complicated to accurately capture an already intricate phenomenon in machining, which harmfully affects virtually all chip formation processes, namely regenerative chatter. This is a self-excited relative vibration between the workpiece and the cutting tool, the consequences of which are seriously adverse. It deteriorates the surface quality and dimensional accuracy of the workpiece, reduces the lifetime of the cutting tool, generates unpleasant

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