Chatter Suppression in Parallel Turning With Unequal Pitch Using Observer Based Cutting Force Estimation

2017 ◽  
Author(s):  
Shinya Sakata ◽  
Takashi Kadota ◽  
Yuki Yamada ◽  
Kenichi Nakanishi ◽  
Hayato Yoshioka ◽  
...  
Keyword(s):  
Cutting Force ◽  
Pitch Angle ◽  
Machine Tools ◽  
Prediction Models ◽  
Chatter Vibration ◽  
Force Estimation ◽  
Chatter Suppression ◽  
The Stability ◽  
Stability Limits ◽  
Turning Test

Parallel turning attracts attention as one of the important technologies for the multi-tasking machine tools. This is because there is a potential to enhance the stability limits compared to turning operation using single tool when cutting conditions are properly selected. Although stability prediction models for parallel turning have been developed in recent years, in-process monitoring technique of chatter is almost out of focus. In this study, to suppress chatter vibration, unequal pitch turning method was proposed. In this method, the upper tool was controlled based on optimum pitch angle calculated from spindle speed and chatter frequency. Chatter frequency was identified from estimated cutting force by disturbance observer. From the result of parallel turning test, it is clear that chatter vibration can be suppressed by controlling the upper tool based on optimum pitch angle.

Chatter Avoidance in Parallel Turning With Unequal Pitch Angle Using Observer-Based Cutting Force Estimation

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Shinya Sakata ◽  
Takashi Kadota ◽  
Yuki Yamada ◽  
Kenichi Nakanishi ◽  
Hayato Yoshioka ◽  
...  
Keyword(s):  
Cutting Force ◽  
Pitch Angle ◽  
Machine Tools ◽  
Prediction Models ◽  
Chatter Vibration ◽  
Force Estimation ◽  
Angle Difference ◽  
The Stability ◽  
Stability Limits ◽  
Turning Test

Parallel turning is garnering attention as one of the most important technologies for multitasking machine tools. This is because a potential exists to enhance the stability limits compared to the turning operation using a single tool when cutting conditions are properly selected. Although stability prediction models for parallel turning have been developed in recent years, in-process monitoring and in-process chatter techniques are almost not discussed. In this study, to suppress chatter vibration, an unequal pitch turning method was proposed. In this method, the upper tool was controlled based on the optimum pitch angle calculated from spindle speed and chatter frequency. Chatter frequency was identified from estimated cutting force by a disturbance observer (DOB). From the result of the parallel turning test, it is clear that chatter vibration can be avoided by controlling the upper tool based on optimum pitch angle. Meanwhile, the pitch angle difference that can suppress chatter had a certain range. Subsequently, the robustness of the optimum pitch angle difference is experimentally evaluated by both the continuous moving test and the stepwise moving test of the pitch angle.

Integrated Chatter Monitoring Based on Sensorless Cutting Force/Torque Estimation in Parallel Turning

2017 ◽  
Vol 11 (2) ◽  
pp. 215-225 ◽  
Author(s):  
Yuki Yamada ◽  
◽  
Takashi Kadota ◽  
Shinya Sakata ◽  
Junji Tachibana ◽  
...  
Keyword(s):  
Cutting Force ◽  
Disturbance Observer ◽  
Prediction Models ◽  
Estimation Methods ◽  
Torque Estimation ◽  
Frequency Components ◽  
Internal Information ◽  
The Stability ◽  
Stability Limits ◽  
Cutting Point

Parallel turning technology is considerably important in future multi-tasking machine tool because it has the potential to enhance the stability limits, compared to turning operations using a single tool. Although stability prediction models for parallel turning have been developed recently, the technique of in-process monitoring of chatter is almost out of focus. In this study, the monitoring of chatter based on the sensorless cutting force/torque technique was evaluated in the parallel turning and cutting of the same surface of an elongated workpiece. Two cutting force/torque estimation methods were evaluated: a conventional disturbance observer (DOB) using internal information from a servomotor and a multi-encoder-based disturbance observer (MEDOB) using load-side position/angular information as well. In the DOB-based monitoring, chatter frequency components were observable regardless of the guideway type and drive system. However, chatter monitoring may be difficult when the angle of the servomotor is changed slightly because of the damping properties of the sliding guideway. In the MEDOB-based monitoring, the waveform of the estimated cutting force reflected the vibrational state at the cutting point well, and the extraction of chatter frequency components became easier regardless of the guideway type.

scholarly journals Investigating Multiscale Phenomena in Machining: The Effect of Cutting-Force Distribution Along the Tool’s Rake Face on Process Stability

2015 ◽  
Author(s):  
Tamás G. Molnár ◽  
Tamás Insperger ◽  
S. John Hogan ◽  
Gábor Stépán
Keyword(s):  
Cutting Force ◽  
Distributed Delay ◽  
Chip Thickness ◽  
Rake Face ◽  
Center Manifold Reduction ◽  
Force System ◽  
Force Magnitude ◽  
Stability Lobe ◽  
The Stability ◽  
Stability Limits

Regenerative machine tool chatter is investigated in a nonlinear single-degree-of-freedom model of turning processes. The nonlinearity arises from the dependence of the cutting-force magnitude on the chip thickness. The cutting-force is modeled as the resultant of a force system distributed along the rake face of the tool. It introduces a distributed delay in the governing equations of the system in addition to the well-known regenerative delay, which is often referred to as the short regenerative effect. The corresponding stability lobe diagrams are depicted, and it is shown that a subcritical Hopf bifurcation occurs along the stability limits in the case of realistic cutting-force distributions. Due to the subcriticality a so-called unsafe zone exists near the stability limits, where the linearly stable cutting process becomes unstable to large perturbations. Based on center-manifold reduction and normal form calculations analytic formulas are obtained to estimate the size of the unsafe zone.

Research on Chatter Suppression in Machining Thin-Walled Components Based on Rigidity Optimization

2010 ◽  
Vol 97-101 ◽  
pp. 1947-1951 ◽  
Author(s):  
Jun Xue Ren ◽  
Bi Qi Yang ◽  
Yong Shou Liang ◽  
Wei Jun Tian ◽  
Chang Feng Yao
Keyword(s):  
Cutting Force ◽  
Material Removal ◽  
Milling Process ◽  
Precision Machining ◽  
Chatter Vibration ◽  
Sequence Optimization ◽  
Chatter Suppression ◽  
Stiffness Optimization ◽  
Machining Errors ◽  
Thin Walled

Precision machining of thin-walled complex components has been a serious challenge, and the machining errors are mainly due to cutting force which can induce tool-workpiece deformation and chatter vibration phenomenon. Based on the principle of stiffness optimization and material removal sequence optimization, rigidity of thin-walled component is greatly improved with non-uniform allowance distribution and spiral milling process techniques.

The Effect of Spindle Speed Variation on Chatter Suppression in Rotating-Tool Machining

2006 ◽  
Vol 505-507 ◽  
pp. 859-864 ◽  
Author(s):  
Chen Jung Li ◽  
A.G. Ulsoy ◽  
W.J. Endres
Keyword(s):  
Spindle Speed ◽  
System Stability ◽  
Constant Delay ◽  
Machining Processes ◽  
Speed Variation ◽  
Chatter Suppression ◽  
Spindle Speed Variation ◽  
Common Process ◽  
The Stability ◽  
Stability Limits

Spindle speed variation (SSV) is one of a number of promising strategies to suppress chatter. Most previous research on SSV stability analysis for nonintermittent machining processes has focused on stationary-bar boring or turning. However, nonintermittent rotating-tool machining is also a common process. This paper investigates the effect of SSV in nonintermittent rotating-tool machining, using rotating-bar boring as an example. This paper takes advantage of the rotating-frame approach and the resulting constant delay in the angle domain to investigate the SSV effect on system stability for rotating-bar boring. The results show that the SSV effect on rotating-bar boring flattens the stability lobes and lifts the tangential stability limits.

Stability as a constraint in sagittal plane human force exertion modeling

1998 ◽  
Vol 1 (1) ◽  
pp. 23-39
Author(s):  
Carter J. Kerk ◽  
Don B. Chaffin ◽  
W. Monroe Keyserling
Keyword(s):  
Muscle Strength ◽  
Ankle Joint ◽  
Coefficient Of Friction ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Whole Body ◽  
The Stability ◽  
Joint Center ◽  
Static Conditions ◽  
Stability Limits

The stability constraints of a two-dimensional static human force exertion capability model (2DHFEC) were evaluated with subjects of varying anthropometry and strength capabilities performing manual exertions. The biomechanical model comprehensively estimated human force exertion capability under sagittally symmetric static conditions using constraints from three classes: stability, joint muscle strength, and coefficient of friction. Experimental results showed the concept of stability must be considered with joint muscle strength capability and coefficient of friction in predicting hand force exertion capability. Information was gained concerning foot modeling parameters as they affect whole-body stability. Findings indicated that stability limits should be placed approximately 37 % the ankle joint center to the posterior-most point of the foot and 130 % the distance from the ankle joint center to the maximal medial protuberance (the ball of the foot). 2DHFEC provided improvements over existing models, especially where horizontal push/pull forces create balance concerns.

scholarly journals Prediction and Stability Assessment of Soft Foundation Settlement of the Fishbone-Shaped Dike Near the Estuary of the Yangtze River Using Machine Learning Methods

2021 ◽  
Vol 13 (7) ◽  
pp. 3744
Author(s):  
Mingcheng Zhu ◽  
Shouqian Li ◽  
Xianglong Wei ◽  
Peng Wang
Keyword(s):  
Extreme Learning Machine ◽  
Prediction Models ◽  
Good Prediction ◽  
Foundation Settlement ◽  
Machine Method ◽  
Settlement Prediction ◽  
Soft Foundation ◽  
Simulation Results ◽  
Learning Machine ◽  
The Stability

Fishbone-shaped dikes are always built on the soft soil submerged in the water, and the soft foundation settlement plays a key role in the stability of these dikes. In this paper, a novel and simple approach was proposed to predict the soft foundation settlement of fishbone dikes by using the extreme learning machine. The extreme learning machine is a single-hidden-layer feedforward network with high regression and classification prediction accuracy. The data-driven settlement prediction models were built based on a small training sample size with a fast learning speed. The simulation results showed that the proposed methods had good prediction performances by facilitating comparisons of the measured data and the predicted data. Furthermore, the final settlement of the dike was predicted by using the models, and the stability of the soft foundation of the fishbone-shaped dikes was assessed based on the simulation results of the proposed model. The findings in this paper suggested that the extreme learning machine method could be an effective tool for the soft foundation settlement prediction and assessment of the fishbone-shaped dikes.

Stability of Milling Operations With Asymmetric Cutter Dynamics in Rotating Coordinates

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Alptunc Comak ◽  
Orkun Ozsahin ◽  
Yusuf Altintas
Keyword(s):  
Time Domain ◽  
Machine Tools ◽  
High Speed ◽  
End Mill ◽  
Spindle Shaft ◽  
Milling Operations ◽  
Stability Model ◽  
Principal Directions ◽  
The Stability ◽  
Rotating Coordinates

High-speed machine tools have parts with both stationary and rotating dynamics. While spindle housing, column, and table have stationary dynamics, rotating parts may have both symmetric (i.e., spindle shaft and tool holder) and asymmetric dynamics (i.e., two-fluted end mill) due to uneven geometry in two principal directions. This paper presents a stability model of dynamic milling operations with combined stationary and rotating dynamics. The stationary modes are superposed to two orthogonal directions in rotating frame by considering the time- and speed-dependent, periodic dynamic milling system. The stability of the system is solved in both frequency and semidiscrete time domain. It is shown that the stability pockets differ significantly when the rotating dynamics of the asymmetric tools are considered. The proposed stability model has been experimentally validated in high-speed milling of an aluminum alloy with a two-fluted, asymmetric helical end mill.

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