Optimisation of variable helix tool geometry for regenerative chatter mitigation

Yusoff, Ahmad Razlan; Sims, Neil D.

doi:10.1016/j.ijmachtools.2010.10.004

Cited by 87 publications

(47 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…An alternative to the time-averaged approach is to consider the Fourier series expansion of the direction factors shown in equation (12). In this case, a frequency domain solution could be achieved by following the detailed methodology described by Wereley.…”

Section: Multi-frequency Formulationmentioning

confidence: 99%

See 1 more Smart Citation

Fast chatter stability prediction for variable helix milling tools

Sims

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

Regenerative chatter is a well-known form of self-excited vibration that limits the productivity of machining operations, in particular for milling. Variable helix tools have been previously proposed as a means of avoiding regenerative chatter, and although recent work has analysed the stability of such tools there has not always been a strong agreement with experimentally observed behaviour. Furthermore, the analysis of variable helix tool stability can be tedious and numerically slow, compared to standard tools. Consequently it has been difficult to gain insight into the potential advantages of variable helix tools. The present work attempts to address these issues, by first developing an efficient approach to variable helix tool stability based upon the Laplace transform. Then, this new analysis method is used to demonstrate the importance of multi-frequency effects and nonlinear cutting stiffness. The work suggests that whilst variable-helix tools can have more operating regions that are stable, un-modelled behaviour (such as nonlinearity and multi-frequency effects) can have a critical influence on the accuracy of model predictions.

show abstract

Section: Multi-frequency Formulationmentioning

confidence: 99%

“…As a result, the variations in time delay could be accounted for within the model. The approach was then used by Yusoff and Sims 12 to optimise tool geometry and perform experimental comparisons. More recently, Jin et al 13 also explored the use of semi-discretisation methods.…”

Section: Introductionmentioning

confidence: 99%

Fast chatter stability prediction for variable helix milling tools

Sims

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

View full text Add to dashboard Cite

show abstract

“…Milling tools with varying helix angle [14,15,16,17,10] or with wavy cutting edges [18,19] are used to achieve a similar effect by distributing the concentrated time delay even further to continuously varying delays over a given delay-interval. In these cases, the pitch angles are changing continuously along the axial coordinate of the tool, which leads to DDE models with distributed time delays [20].…”

Section: Introductionmentioning

confidence: 99%

Effect of wavy tool path on the stability properties of milling by the implicit subspace iteration method

Tóth

Bachrathy

Stépàn

2016

Int J Adv Manuf Technol

View full text Add to dashboard Cite

There are several practical methods to reduce machine tool vibrations that have negative effects especially on the quality of the machined surface. The most intricate vibration is the regenerative one originated in a delay effect of cutting processes. One group of the methods that may be successful in avoiding regenerative vibrations is the appropriate variation of the corresponding time delay. This study presents the stability analysis of milling processes in case of an especially intricate way of varying the delay in time: the radial depth of cut is varied in face milling resulting in a wavy tool path. The combination of the semidiscretization method and the implicit subspace iteration method is introduced to present an efficient way of calculating stability charts that provide conclusions regarding the use of this method in eliminating chatter.Keywords: chatter; wavy tool path; implicit subspace iteration; semi-discretization IntroductionMachine tool chatter has a negative effect on the lifetime of the machine tools and on the quality of the surface finish of the workpiece [1][2][3][4]. This self-excited vibration is originated in the so-called surface regeneration effect [3][4][5]. The mathematical modeling of chatter is rooted in the theory of delay differential equations (DDEs) [6], and the primary cause of instability is the presence of a large time delay in the cutting processes.A constant single point delay appears in the DDE of the commonly used mechanical models of milling processes at constant spindle speed if conventional helical tools with even pitch angles are used. The time delays are proportional to the pitch angles between two neighboring cutting edges, and inversely proportional to the spindle speed.Different tool geometries and operating conditions have been developed in order to improve the stability properties of cutting processes by weakening the negative effect of the inherent time delay by disturbing the concentrated nature of the delayed term in the corresponding equations of motion.In case of milling processes, the concentrated nature of the time delay can be changed to a more disturbed one by introducing uneven pitch angles between the cutting edges [7,8,9,10]. This idea results in multiple discrete time delays in the system, whose number depends on the number of teeth of the tool and the applied pitch angle distribution [11,12,13].Milling tools with varying helix angle [14,15,16,17,10] or with wavy cutting edges [18,19] are used to achieve a similar effect by distributing the concentrated time delay even further to continuously varying delays over a given delay-interval. In these cases, the pitch angles are changing continuously along the axial coordinate of the tool, which leads to DDE models with distributed time delays [20]. In addition to the continuously varying

show abstract

“…To the authors' knowledge, only Turner [12], Sims [13] and Yusoff [14] considered the cases of variable helix angle in their studies. Sims proposed the tool could be discrete into a number of axial layers to solve the problem of variable helix angle.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and stability predictions of variable helix milling

Xie¹

2015

Proceedings of the 2015 International Conference on Mechatronics, Electronic, Industrial and Control Engineering

View full text Add to dashboard Cite

Abstract-In milling, it is important to research the stability lobes charts which determine stable regions where no chatter occurs. This paper presents the nonlinear model of milling considering the variable helix angle. Base on this model, an improved semi-discretization method is used to predict stability. Due to the delay between each flute varies along the axial depth of the tool in milling, the cutting tool is discrete into some axial layers to simplify calculate. The effects of variable helix angle and uniform helix angle on the corresponding stability charts are explored, it is revealed that many unstable islands arise in the low radial immersion ratio. However, as the radial immersion rates increase, variable helix angle has a little effect on stability. This fully shows that the helix angle plays an important impact for stability. Meantime this also confirms our proposed method can accurately capture unstable phenomenon at low radial immersion milling operations.

show abstract

Optimisation of variable helix tool geometry for regenerative chatter mitigation

Cited by 87 publications

References 22 publications

Fast chatter stability prediction for variable helix milling tools

Fast chatter stability prediction for variable helix milling tools

Effect of wavy tool path on the stability properties of milling by the implicit subspace iteration method

Dynamics and stability predictions of variable helix milling

Contact Info

Product

Resources

About