scholarly journals Optimum Selection of Variable Pitch for Chatter Suppression in Face Milling Operations

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 112 ◽  
Author(s):  
Alex Iglesias ◽  
Zoltan Dombovari ◽  
German Gonzalez ◽  
Jokin Munoa ◽  
Gabor Stepan
Keyword(s):  
Removal Rate ◽  
Face Milling ◽  
Heavy Duty ◽  
Variable Pitch ◽  
Thin Walls ◽  
Chatter Suppression ◽  
Milling Operations ◽  
Optimum Selection ◽  
Cutting Capacity ◽  
Selection Of

Cutting capacity can be seriously limited in heavy duty face milling processes due to self-excited structural vibrations. Special geometry tools and, specifically, variable pitch milling tools have been extensively used in aeronautic applications with the purpose of removing these detrimental chatter vibrations, where high frequency chatter related to slender tools or thin walls limits productivity. However, the application of this technique in heavy duty face milling operations has not been thoroughly explored. In this paper, a method for the definition of the optimum angles between inserts is presented, based on the optimum pitch angle and the stabilizability diagrams. These diagrams are obtained through the brute force (BF) iterative method, which basically consists of an iterative maximization of the stability by using the semidiscretization method. From the observed results, hints for the selection of the optimum pitch pattern and the optimum values of the angles between inserts are presented. A practical application is implemented and the cutting performance when using an optimized variable pitch tool is assessed. It is concluded that with an optimum selection of the pitch, the material removal rate can be improved up to three times. Finally, the existence of two more different stability lobe families related to the saddle-node and flip type stability losses is demonstrated.

Optimal Selection of Machining Parameters by Genetic Algorithms for Face-Milling Operations Based on Minimum Unit Machining Time

2012 ◽  
Vol 602-604 ◽  
pp. 1989-1992 ◽  
Author(s):  
Pei Qing Yang ◽  
Li Bao An
Keyword(s):  
Face Milling ◽  
Machining Process ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Machining Time ◽  
Milling Operations ◽  
Tool Replacement ◽  
Optimal Values ◽  
Cutting Speeds ◽  
Selection Of

In this paper, the parameter optimization problem for face-milling operations is studied. A mathematical model is developed in order to minimize unit machining time. The machining process needs one finishing pass and at least one roughing pass depending on the total depth of cut. Maximum and minimum allowable cutting speeds, feed rates and depths of cut, as well as tool life, surface roughness, cutting force and cutting power consumption are constraints of the model. Optimal values of machining parameters are found by a genetic algorithm (GA). The influence of tool replacement time and GA operators is evaluated.

Update on High-Speed Milling Dynamics

1990 ◽  
Vol 112 (2) ◽  
pp. 142-149 ◽  
Author(s):  
S. Smith ◽  
J. Tlusty
Keyword(s):  
High Speed ◽  
Metal Removal ◽  
Removal Rate ◽  
Spindle Speed ◽  
Stability Lobe ◽  
Milling Operations ◽  
Force Signal ◽  
The Stability ◽  
Milling Dynamics ◽  
Selection Of

As spindle speeds and power have increased, the possibility of using the stability lobe phenomena to substantially increase the metal removal rate has become more attractive, and selection of optimum spindle speeds has become an important consideration. It is shown that, for many milling operations, it is desirable to set the tooth frequency equal to the natural frequency. At this spindle speed, the development of resonant forced vibration is actually inhibited by regeneration of waviness. An algorithm is presented for automatically selecting the optimum spindle speed based on the cutting force signal.

scholarly journals Electric Discharge Grinding of Polycrystalline Diamond Materials

2012 ◽  
Vol 271-272 ◽  
pp. 333-337 ◽  
Author(s):  
Song Lin Ding ◽  
John P.T. Mo ◽  
Milan Brandt ◽  
Richard Webb
Keyword(s):  
Electrical Discharge ◽  
Material Removal ◽  
Working Condition ◽  
Removal Rate ◽  
Polycrystalline Diamond ◽  
Optimal Parameters ◽  
Power Generator ◽  
The Poor ◽  
Edm Process ◽  
Selection Of

The poor electric conductivity of polycrystalline diamond (PCD) makes it difficult to machine with the conventional EDM process. Inappropriate selection of parameters of the power generator and the servo system leads to unstable working condition and low material removal rate. This paper introduces a method to find optimal parameters in the Electrical Discharge Grinding (EDG) of PCD materials with Taguchi method. The theory and detailed procedures are presented, experimental results are analyzed. The optimized configuration was validated through confirmation tests.

Mathematical Modeling of Machining Parameters in Electrical Discharge Machining with Cu-B4C Composite Electrode

2012 ◽  
Vol 488-489 ◽  
pp. 871-875
Author(s):  
V. Anandakrishnan ◽  
V. Senthilkumar
Keyword(s):  
Mathematical Models ◽  
Current Pulse ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Removal Rate ◽  
Machining Parameters ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time ◽  
Selection Of

Copper based metal matrix composite reinforced with Boron Carbide is a newly developed Electrical Discharge Machining (EDM) electrode showing better performance than the conventional copper based electrode. Right selection of machining parameters such as current, pulse on time and pulse off time is one of the most important aspects in EDM. In this paper an attempt has been made to develop mathematical models for relating the Material Removal Rate (MRR), Tool Removal Rate (TRR) and Surface roughness (Ra) to machining parameters (current, pulse-on time and pulse-off time). Furthermore, a study was carried out to analyze thSubscript texte effects of machining parameters on various performance parameters such as, MRR, TRR and Ra. The results of Analysis of Variance (ANOVA) indicate that the proposed mathematical models, can adequately describe the performance within the limits of the factors being studied. Response surface modeling is used to develop surface and contour graphs to analyze the effects of EDM input parameters on outer parameters.

Numerical investigation of chatter suppression in milling using active fixtures in open-loop control

2016 ◽  
Vol 24 (9) ◽  
pp. 1757-1773 ◽  
Author(s):  
Lorenzo Sallese ◽  
Niccolò Grossi ◽  
Antonio Scippa ◽  
Gianni Campatelli
Keyword(s):  
Numerical Investigation ◽  
Removal Rate ◽  
Active Vibration Control ◽  
Open Loop ◽  
Influential Factors ◽  
Depth Of Cut ◽  
Control Logic ◽  
Loop Control ◽  
Testing Environment ◽  
Chatter Suppression

Among the chatter suppression techniques in milling, active fixtures seem to be the most industrially oriented, mainly because these devices could be directly retrofittable to a variety of machine tools. The actual performances strongly depend on fixture design and the control logic employed. The usual approach in the literature, derived from general active vibration control applications, is based on the employment of adaptive closed-loop controls aimed at mitigating the amplitude of chatter frequencies with targeted counteracting vibrations. Whilst this approach has proven its effectiveness, a general application would demand a wide actuation bandwidth that is practically impeded by inertial forces and actuator-related issues. This paper presents the study of the performance of alternative open-loop actuation strategies in suppressing chatter phenomena, aiming at limiting the required actuation bandwidth. A dedicated time-domain simulation model, integrating fixture dynamics and the features of piezoelectric actuators, is developed and experimentally validated in order to be used as a testing environment to assess the effectiveness of the proposed actuation strategies. An extensive numerical investigation is then carried out to highlight the most influential factors in assessing the capability of suppressing chatter vibrations. The results clearly demonstrated that the regenerative effect could be effectively disrupted by actuation frequencies close to half the tooth-pass frequency, as long as adequate displacement is provided by the actuators. This could sensibly increase the critical axial depth of cut and hence improve the achievable material removal rate, as discussed in the paper.

Design of LQR based PI controller with optimum selection of weights for Time Delay Process

2021 ◽  
Author(s):  
K Harshavardhana Reddy ◽  
Sachin Sharma ◽  
B. Madhuri ◽  
K Shivarama Krishna
Keyword(s):  
Time Delay ◽  
Pi Controller ◽  
Optimum Selection ◽  
Selection Of
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