scholarly journals Hilbert-Huang Transform Analysis of Machining Stability in Ball-Nose End-Milling of Curved Surface

2020 ◽  
Vol 14 (3) ◽  
pp. 500-511
Author(s):  
Muizuddin Azka ◽  
Keiji Yamada ◽  
Mahfudz Al Huda ◽  
Kyosuke Mani ◽  
Ryutaro Tanaka ◽  
...  
Keyword(s):  
Cutting Force ◽  
Inclination Angle ◽  
End Milling ◽  
Curved Surface ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
Machining Errors ◽  
Cutting Velocity ◽  
Cylindrical Workpiece ◽  
The Stability

This paper investigates the machining stability in ball-end-milling of curved surface in which the inclination of tool continuously changes. Initially, the influence of inclination angle is geometrically investigated on the parameters such as immersion angle and cutting velocity. Then, the paper presents the stability lobe diagrams of the process. Curved surface milling is simulated by slot milling on a cylindrical workpiece using a ball-end-mill to obtain the cutting force and vibration, which are used for fast-Fourier transform and Hilbert-Huang transform (HHT) analyses. Experimental results show that the cutting force increases, and the stability becomes worse with the inclination angle, while the machining errors decrease with the inclination. The vibration analysis showed that the HHT can detect the transition from stable to unstable during milling of curved surface in the time-frequency plots.

Analysis of Cutting Force in Elastomer End-Milling

2017 ◽  
Vol 11 (6) ◽  
pp. 958-963
Author(s):  
Koji Teramoto ◽  
◽  
Takahiro Kunishima ◽  
Hiroki Matsumoto
Keyword(s):  
Parameter Identification ◽  
Cutting Force ◽  
Cutting Forces ◽  
End Milling ◽  
Process Models ◽  
Force Model ◽  
Cutting Force Model ◽  
Cutting Force Prediction ◽  
Force Prediction ◽  
The Stability

Elastomer end-milling is attracting attention for its role in the small-lot production of elastomeric parts. In order to apply end-milling to the production of elastomeric parts, it is important that the workpiece be held stably to avoid deformation. To evaluate the stability of workholding, it is necessary to predict cutting forces in elastomer end-milling. Cutting force prediction for metal workpiece end-milling has been investigated for many years, and many process models for end-milling have been proposed. However, the applicability of these models to elastomer end-milling has not been discussed. In this paper, the characteristics of the cutting force in elastomer end-milling are evaluated experimentally. A standard cutting force model and its parameter identification method are introduced. By using this cutting force model, measured cutting forces are compared against the calculated results. The comparison makes it clear that the standard cutting force model for metal end-milling can be applied to down milling for a rough evaluation.

Stability Predictions for End Milling Operations With a Nonlinear Cutting Force Model

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Alex Elías-Zúñiga ◽  
Jovanny Pacheco-Bolívar ◽  
Francisco Araya ◽  
Alejandro Martínez-López ◽  
Oscar Martínez-Romero ◽  
...  
Keyword(s):  
Experimental Data ◽  
Cutting Force ◽  
End Milling ◽  
Stability Conditions ◽  
Force Model ◽  
Process Stability ◽  
Cutting Force Model ◽  
Stability Lobes ◽  
Milling Operations ◽  
The Stability

The aim of this paper is to obtain the stability lobes for milling operations with a nonlinear cutting force model. The work is focused on the generation of stability lobes based on a formulation with Chebyshev polynomials and the semidiscretization method, considering a nonlinear cutting force model. Comparisons were conducted between experimental data at 5% radial immersion with aluminum workpiece and predictions based on Chebyshev and semidiscretization. In all cases, the use of nonlinear cutting force model provides better prediction of process stability conditions.

scholarly journals Research on High-Frequency Combination Coding-Based SSVEP-BCIs and Its Signal Processing Algorithms

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Feng Zhang ◽  
Chengcheng Han ◽  
Lili Li ◽  
Xin Zhang ◽  
Jun Xie ◽  
...  
Keyword(s):  
High Frequency ◽  
Recognition Rate ◽  
Epileptic Seizures ◽  
New Paradigm ◽  
Safety Hazards ◽  
Hilbert Huang Transform ◽  
Time Frequency ◽  
High Frequency Response ◽  
Signal Processing Algorithms ◽  
The Stability

This study presents a new steady-state visual evoked potential (SSVEP) paradigm for brain computer interface (BCI) systems. The new paradigm is High-Frequency Combination Coding-Based SSVEP (HFCC-SSVEP). The goal of this study is to increase the number of targets using fewer stimulation frequencies, with diminishing subject’s fatigue and reducing the risk of photosensitive epileptic seizures. This paper investigated the HFCC-SSVEP high-frequency response (beyond 25 Hz) for 3 frequencies (25 Hz, 33.33 Hz, and 40 Hz). HFCC-SSVEP producesnnwithnhigh stimulation frequencies through Time Series Combination Code. Furthermore, The Improved Hilbert-Huang Transform (IHHT) is adopted to extract time-frequency feature of the proposed SSVEP response. Lastly, the differentiation combination (DC) method is proposed to select the combination coding sequence in order to increase the recognition rate; as a result, IHHT algorithm and DC method for the proposed SSVEP paradigm in this study increase recognition efficiency so as to improve ITR and increase the stability of the BCI system. Furthermore, SSVEPs evoked by high-frequency stimuli (beyond 25 Hz) minimally diminish subject’s fatigue and prevent safety hazards linked to photo-induced epileptic seizures. This study tests five subjects in order to verify the feasibility of the proposed method.

Anticipation of Stability Limits for Two Degree-of-Freedom Interrupted Milling

2009 ◽  
Vol 25 (1) ◽  
pp. 41-48
Author(s):  
B. M. Imani ◽  
M. H. Sadeghi ◽  
M. Kazemi
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Experimental Tests ◽  
Helix Angle ◽  
Vibratory System ◽  
Element Analysis ◽  
Stability Behavior ◽  
Milling Operations ◽  
The Stability ◽  
Low Radial Immersion

AbstractMilling is becoming an increasingly universal machining operation for producing parts used in aerospace, automotive, and life science engineering industries. The characteristics common to such parts are a high level of complexity and structural flexibility, both of which usually necessitate using low radial immersion milling operations. Low radial immersion milling operations involve interrupted cutting which induces chatter vibration under certain cutting conditions. The stability behavior of low immersion helical end milling processes is investigated in this paper. Time Finite Element Analysis (TFEA) is suggested for an approximate solution for delayed differential equations encountered during interrupted milling. An improved TFEA is proposed which includes the effects of helix angle variations on cutting force, cutting time and specific cutting force coefficients for a 2 DOF vibratory system. To verify the proposed method, experimental tests have been conducted which prove that the improved TFEA method accurately predicts the stability behavior of low immersion milling.

Supporting Method for Thin Parts Having Curved Surfaces – Improvement of End Milling Accuracy by Using Low-Melting Point Alloy and Elastomer Support –

2019 ◽  
Vol 13 (1) ◽  
pp. 92-100 ◽  
Author(s):  
Akinori Saito ◽  
Shinya Kato ◽  
Mitsuo Nagao ◽  
◽  
Keyword(s):  
Melting Point ◽  
Cutting Force ◽  
Turbine Blade ◽  
End Milling ◽  
High Accuracy ◽  
Curved Surface ◽  
Machining Accuracy ◽  
Curved Surfaces ◽  
Mechanical Parts ◽  
Experimental Part

Many mechanical parts have complicated and delicate shapes for improving their functionality and designability. To machine thin parts with high accuracy, it is necessary to reduce the cutting force induced on the workpiece or to clamp the workpiece optimally. Generally, cores are placed in the workpiece to fix it firmly at the production site. However, the cores must be adjusted precisely in accordance with the shape of the workpiece. A low-point melting alloy can be conveniently used instead of the cores. In this study, the influence of the supporting method for thin parts having a curved surface using a low-melting point alloy on machining accuracy is experimentally investigated. The turbine blade is selected as the experimental part. The shape is produced via end milling. The experimental results indicate that a low-melting point alloy can be closely fitted to the supporting curved surface of the turbine blade because the volume of the low-melting point alloy increases in the solidification. However, the machining accuracy is degraded when the turbine blade is deformed owing to the characteristics of the low-melting point alloy. A support method using the low-melting point alloy and an elastomer support is proposed to improve the machining accuracy. The effectiveness of the proposed method is experimentally confirmed.

Research on High Speed Ball-End Milling Forces

2006 ◽  
Vol 315-316 ◽  
pp. 25-29 ◽  
Author(s):  
Bin Jiang ◽  
Min Li Zheng ◽  
Shu Cai Yang ◽  
M. Fu
Keyword(s):  
Cutting Force ◽  
Inclination Angle ◽  
High Speed ◽  
End Milling ◽  
Complex Surface ◽  
Differential Method ◽  
Unstable State ◽  
Milling Force ◽  
Ball End Milling ◽  
Milling Forces

Based on the experiment of high speed milling ball-end milling forces, the model of ball-end milling force is established for high speed machining complex surface by differential method, and research on the principle of high speed ball-end milling force. Results show that the parameters of cutting layer are subjected to varying curvature of complex surface, and place in the unstable state, cutting force decreases as the curvature and the inclination angle increase. By means of lessening cutting speed’s grads and adjusting the inclination angle and the path interval of cutter to the variety of curvature, cutting force and its fluctuation can be depressed availably; the process of high speed ball-end milling can be obviously improved.

Research on the Tool Wear Mechanism of Cemented Carbide Ball End Mill Machining Titanium Alloy

2016 ◽  
Vol 836-837 ◽  
pp. 318-325 ◽  
Author(s):  
Yu Hua Zhang ◽  
Shu Cai Yang ◽  
Chuang Feng
Keyword(s):  
Tool Wear ◽  
Cutting Force ◽  
High Efficiency ◽  
Convex Surface ◽  
End Milling ◽  
Cutting Parameters ◽  
Least Square ◽  
Curved Surface ◽  
Force Model ◽  
Mill Machining

In order to achieve the high efficiency machining of titanium, the cutting force model is verified through the cutting experimental platform in machining cant and curved surface with ball end milling. And then the influence of cutting parameters and surface curvature on cutting force and tool wear are investigated. Finally, the prediction model of tool wear is established based on the orthogonal test and the least square method. This study proposes that the tool wear and each tooth feeding have a major impact on cutting force and that the convex surface from a small curvature to larger and the concave surface from a large curvature to smaller can effectively improve the life of tool in machining curved surface.

Dynamics and Stability Prediction of Five-Axis Flat-End Milling

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
YaoAn Lu ◽  
Ye Ding ◽  
LiMin Zhu
Keyword(s):  
Cutting Force ◽  
End Milling ◽  
Stability Prediction ◽  
Tool Orientation ◽  
Cutting Force Prediction ◽  
Vector Method ◽  
Force Prediction ◽  
Flat End Milling ◽  
The Stability ◽  
Five Axis

The tool orientation of a flat-end cutter, determined by the lead and tilt angles of the cutter, can be optimized to increase the machining strip width. However, few studies focus on the effects of tool orientation on the five-axis milling process stability with flat-end cutters. Stability prediction starts with cutting force prediction, and the cutting force prediction is affected by the cutter-workpiece engagement (CWE). The engagement geometries occur between the flat-end cutter and the in-process workpiece (IPW) are complicated in five-axis milling, making the stability analysis for five-axis flat-end milling difficult. The robust discrete vector method (DVM) is adopted to identify the CWE for flat-end millings, and it can be extended to apply to general cutter millings. The milling system is then modeled as a two-degrees-of-freedom spring-mass-damper system with the predicted cutting forces. Thereafter, a general formulation for the dynamic milling system is developed considering the regenerative effect and the mode coupling effect simultaneously. Finally, an enhanced numerical integration method (NIM) is developed to predict the stability limits in flat-end milling with different tool orientations. Effectiveness of the strategy is validated by conducting experiments on five-axis flat-end milling.

Turning Dynamics: Part 1 — Experimental Analysis

2012 ◽  
Author(s):  
Eric B. Halfmann ◽  
C. Steve Suh ◽  
N. P. Hung
Keyword(s):  
Instantaneous Frequency ◽  
Period Doubling ◽  
Displacement Sensor ◽  
Laser Displacement Sensor ◽  
Turning Process ◽  
Time Frequency ◽  
Spectral Components ◽  
Tool Vibrations ◽  
Exact Moment ◽  
The Stability

The workpiece and tool vibrations in a lathe are experimentally studied to establish improved understanding of cutting dynamics that would support efforts in exceeding the current limits of the turning process. A Keyence laser displacement sensor is employed to monitor the workpiece and tool vibrations during chatter-free and chatter cutting. A procedure is developed that utilizes instantaneous frequency (IF) to identify the modes related to measurement noise and those innate of the cutting process. Instantaneous frequency is shown to thoroughly characterize the underlying turning dynamics and identify the exact moment in time when chatter fully developed. That IF provides the needed resolution for identifying the onset of chatter suggests that the stability of the process should be monitored in the time-frequency domain to effectively detect and characterize machining instability. It is determined that for the cutting tests performed chatters of the workpiece and tool are associated with the changing of the spectral components and more specifically period-doubling bifurcation. The analysis presented provides a view of the underlying dynamics of the lathe process which has not been experimentally observed before.

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

Sign in / Sign up

Export Citation Format

Share Document