Control of Regenerative Self-Excited Vibrations in the Milling Process

2019 ◽  
Vol 20 (5) ◽  
pp. 291-298
Author(s):  
O. B. Shagniev ◽  
I. K. Shanshin ◽  
S. F. Burdakov
Keyword(s):  
Control Algorithm ◽  
Amplitude Spectrum ◽  
Movement Control ◽  
Depth Of Cut ◽  
Robot Arm ◽  
Machined Surface ◽  
Elastic Suspension ◽  
Work Surface ◽  
Subsequent Decrease ◽  
Axial Depth

The problem of the occurrence and rapid suppression of vibrations arising in the process of milling using robot arm is considered. It is assumed that the tool (cutter) is connected with the robot by an elastic suspension, which is used for the force sensation of the robot. Based on the mathematical model of regenerative self-excited vibrations (chattering), the simulation of the system "robot-tool-work surface" was carried out. The tool moves evenly along the work surface with a given pressure on it. The cutter is pressed using the position-force control algorithm based on two PID-controllers with coordinate and force feedbacks. It provides the necessary axial depth of cut. Uniform movement along the work surface is carried out using the velocity control algorithm based on PID-controller with velocity feedback. It provides the required tool feed. Several authors have experimentally and analytically shown that in the process of milling "on the track" unstable regenerative self-oscillations can occur. Track remains on the machined surface during the previous cutter tooth pass. Chattering is a deterrent to increase productivity which mainly depends on rotation speed of cutter and the axial depth of cut. In this paper we consider the possibility of promptly detecting the onset of unstable auto-oscillations from the amplitude spectrum of the sensor readings of the horizontal forces of interaction between the instrument and the work surface. The amplitude spectrum is obtained using the fast Fourier transform, which allows to promptly determine the beginning of unstable processes in system. The subsequent decrease of the axial depth of cut (within one to two percent) almost completely stabilizes the cutting process. This paper proposes a variant of adaptation contour for the robot vertical movement control system based on the allowable change of the axial depth of cut.

Experimentation on the Residual Stresses Generated by Endmilling

2000 ◽  
Vol 123 (4) ◽  
pp. 748-753 ◽  
Author(s):  
Kurt Jacobus ◽  
S. G. Kapoor ◽  
R. E. DeVor
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Design Of Experiments ◽  
End Milling ◽  
Depth Of Cut ◽  
Coordinate Frame ◽  
Machined Surface ◽  
Multiple Points ◽  
Stress Measurements ◽  
Axial Depth

Residual stress measurements from endmilling of annealed AISI 4340 have been made at multiple points within the cut geometry to investigate the effects of location on the machining-induced residual stresses from endmilling. In the same experiments the effects of axial depth of cut and feed on the residual stresses induced in the machined surface have been investigated in a design of experiments framework. The experimentation demonstrates that location, feed and axial depth of cut have strong influences on the machining-induced residual stresses from end-milling when expressed in a workpiece coordinate frame. In addition, expression of the residual stresses in a coordinate frame fixed in the tool demonstrates a simplification in the residual stresses from endmilling in that the stresses at multiple locations within the cut geometry show strong similarities when expressed in this coordinate frame.

Experimental Investigation on Cutting Performance of Face Milling Cutter

2012 ◽  
Vol 217-219 ◽  
pp. 2133-2137
Author(s):  
Bing Yan ◽  
Yang Li ◽  
Wei Wang ◽  
Hao Feng
Keyword(s):  
Cutting Force ◽  
High Speed ◽  
Cutting Parameters ◽  
Rake Angle ◽  
Tool Geometry ◽  
Depth Of Cut ◽  
Machined Surface ◽  
High Speed Cutting ◽  
Angle Effect ◽  
Axial Depth

The cutting tool geometry and cutting parameters have a great impact on cutting force, while cutting force is an important factor which affecting the tool life. High speed cutting experiments have shown that when slight axial depth of cut is adopted, rake angle effect on main cutting force significantly. When cutting aluminum alloy, the roughness of machined surface decrease with increasing tool rake angle. The axial depth of cut does not have a big influence on machined surface ’s roughness.

Surface Roughness Identification in End Milling Using Vibration Signals and Fuzzy Clustering

2016 ◽  
Author(s):  
Issam Abu-Mahfouz ◽  
Amit Banerjee ◽  
A. H. M. Esfakur Rahman
Keyword(s):  
Surface Roughness ◽  
Fuzzy Clustering ◽  
Wavelet Transforms ◽  
Fourier Transforms ◽  
End Milling ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Machined Surface ◽  
Vibration Signals

The study presented involves the identification of surface roughness in Aluminum work pieces in an end milling process using fuzzy clustering of vibration signals. Vibration signals are experimentally acquired using an accelerometer for varying cutting conditions such as spindle speed, feed rate and depth of cut. Features are then extracted by processing the acquired signals in both the time and frequency domain. Techniques based on statistical parameters, Fast Fourier Transforms (FFT) and the Continuous Wavelet Transforms (CWT) are utilized for feature extraction. The surface roughness of the machined surface is also measured. In this study, fuzzy clustering is used to partition the feature sets, followed by a correlation with the experimentally obtained surface roughness measurements. The fuzzifier and the number of clusters are varied and it is found that the partitions produced by fuzzy clustering in the vibration signal feature space are related to the partitions based on cutting conditions with surface roughness as the output parameter. The results based on limited simulations are encouraging and work is underway to develop a larger framework for online cutting condition monitoring system for end milling.

scholarly journals Surface Integrity Investigation to Determine Rough Milling Effects for Assessment of Machining Allowance for Subsequent Finish Milling of Alloy 718

2021 ◽  
Vol 5 (2) ◽  
pp. 48
Author(s):  
Jonas Holmberg ◽  
Anders Wretland ◽  
Johan Berglund ◽  
Tomas Beno ◽  
Anton Milesic Karlsson
Keyword(s):  
Surface Integrity ◽  
Milling Process ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Milling Operations ◽  
Milling Operation ◽  
Machining Allowance ◽  
Rough Milling

The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm.

The Effects of Cutting Parameters on Work-Hardening of Milling Invar 36

2015 ◽  
Vol 1089 ◽  
pp. 373-376
Author(s):  
Xing Wei Zheng ◽  
Guo Fu Ying ◽  
Yan Chen ◽  
Yu Can Fu
Keyword(s):  
Work Hardening ◽  
Lattice Distortion ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Metallographic Structure ◽  
Metallographic Observation ◽  
Coated Carbide ◽  
Carbide Insert ◽  
Axial Depth

An experiment of face milling of Invar36 was conducted by using coated carbide insert, the microhardness was tested and the metallographic structure was observed to figure out the principles of work-hardening. The results showed that the depth of work-hardening ranges from 80μm to 160μm among the parameters selected in the experiments. The degree and the depth of work-hardening were significantly affected by the axial depth of cut and feed per tooth. The degree and the depth of work-hardening showed a tendency to increase with the increase of the axial depth of cut and feed per tooth. Compared with the axial depth of cut and feed per tooth, cutting speed had less influence on the degree and depth of work-hardening. The degree and depth of work- hardening decreased slowly with the increase of cutting speed. Metallographic observation showed that work-hardening layer consisted of the thermal force influenced layer and the force influenced layer, while the amorphous metallographic structure was observed in the thermal force influenced layer, and lattice distortion was observed in the force influenced layer.

scholarly journals Sliding Mode Robot Control with Friction and Payload Estimation

2004 ◽  
Vol 8 (5) ◽  
pp. 553-561 ◽  
Author(s):  
Lörinc Márton ◽  
◽  
Béla Lantos ◽  
Keyword(s):  
Robot Control ◽  
Control Algorithm ◽  
Lyapunov Method ◽  
Sliding Mode ◽  
Robot Arm ◽  
Tracking Accuracy ◽  
Parameter Adaptation ◽  
Robust Parameter ◽  
Payload Mass ◽  
Friction Parameters

The paper deals with robust motion control of robotic systems with unknown friction parameters and payload mass. The parameters of the robot arm were considered known with a given precision. To solve the control of the robot with unknown payload mass and friction parameters, sliding mode control algorithm was proposed combined with robust parameter adaptation techniques. Using Lyapunov method it was shown that the resulting controller achieves a guaranteed final tracking accuracy. Simulation results are presented to illustrate the effectiveness and achievable control performance of the proposed scheme.

Theoretical Analysis and Experimental Verification of Validity Finished by Abrasive Jet with Grinding Wheel as Restraint

2008 ◽  
Vol 53-54 ◽  
pp. 39-44
Author(s):  
Chang He Li ◽  
Shi Chao Xiu ◽  
Yu Cheng Ding ◽  
Guang Qi Cai
Keyword(s):  
Ground Surface ◽  
Hydrodynamic Pressure ◽  
Machining Process ◽  
Grinding Wheel ◽  
Workpiece Material ◽  
Machined Surface ◽  
Mean Values ◽  
Work Surface ◽  
Geometry Parameter ◽  
Parameter Values

The integration manufacturing technology is a kind of compound precision finishing process that combined grinding with abrasive jet finishing, in which inject slurry of abrasive and liquid solvent into grinding zone between grinding wheel and work surface under no radial feed condition when workpiece grinding were accomplished. The abrasive particles are driven and energized by the rotating grinding wheel and liquid hydrodynamic pressure and increased slurry speed between grinding wheel and work surface to achieve micro removal finishing. In the paper, the machining process validity was verified by experimental investigation. Experiments were performed with plane grinder M7120 and workpiece material 40Cr steel which was ground with the surface roughness mean values of Ra=0.6μm. The machined surface morphology was studied using Scanning Electron Microscope (SEM) and metallography microscope and microcosmic geometry parameters were measured with TALYSURF5 instrument respectively. The experimental results show the novelty process method, not only can obviously diminish longitudinal geometry parameter values of ground surface, but also can attain isotropy surface and uniformity veins at parallel and perpendicular machining direction. Furthermore, the finished surface has little comparability compared to grinding machining surface and the process validity was verified.

Machining Evaluation of High-Speed Milling for Thin-Wall Machining of Al7075-T651

2014 ◽  
Vol 541-542 ◽  
pp. 785-791 ◽  
Author(s):  
Joon Young Koo ◽  
Pyeong Ho Kim ◽  
Moon Ho Cho ◽  
Hyuk Kim ◽  
Jeong Kyu Oh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Cutting Forces ◽  
High Speed ◽  
Surface Condition ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Thin Wall ◽  
Machined Surface ◽  
High Speed Milling

This paper presents finite element method (FEM) and experimental analysis on high-speed milling for thin-wall machining of Al7075-T651. Changes in cutting forces, temperature, and chip morphology according to cutting conditions are analyzed using FEM. Results of machining experiments are analyzed in terms of cutting forces and surface integrity such as surface roughness and surface condition. Variables of cutting conditions are feed per tooth, spindle speed, and axial depth of cut. Cutting conditions to improve surface integrity were investigated by analysis on cutting forces and surface roughness, and machined surface condition.

Thermal hardening and calculation of the mathematical model of face milling of parts made of steel 95X18-Sh to improve the quality of the surface layer

2021 ◽  
pp. 200-206
Author(s):  
I.N. Sedinin ◽  
V.F. Makarov
Keyword(s):  
Mathematical Model ◽  
Cutting Speed ◽  
Physical And Mechanical Properties ◽  
Face Milling ◽  
Experiment Planning ◽  
Depth Of Cut ◽  
Machined Surface ◽  
The Mathematical Model ◽  
Full Factorial

It is considered the complex of operations of the technological process for the heat treatment of steel 95X18-Sh, as a result of which the material of the samples increases the hardness to 59...61 HRC, and also improves the physical and mechanical properties. A full-scale full factorial experiment of face milling of samples was carried out using the method of mathematical planning. In the experiments, a high-precision machine and a carbide cutting tool were used. To calculate the values of the roughness function, the following are taken as independent variables: cutting speed, feed per tooth and depth of cut. In order to determine the coefficients of the linear equation, a central compositional orthogonal plan of the second order for three factors was used. A matrix of levels of variation of independent variable factors and a matrix of experiment planning were compiled. A regression analysis of the obtained experimental statistical data was carried out using the Microsoft Excel, Statistica and Wolfram Alpha programs. As a result of the calculations, a mathematical model of the roughness of the machined surface and optimal cutting conditions were determined.

Performance assessment of energy efficient and eco-friendly turning of Nimonic C-263: A comparative study on MQL and cryogenic machining

2021 ◽  
pp. 095440542110619
Author(s):  
Prashant S Jadhav ◽  
Chinmaya P Mohanty
Keyword(s):  
Work Environment ◽  
Manufacturing Industry ◽  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Work Piece ◽  
Cryogenic Machining ◽  
Machined Surface ◽  
Machining Strategies ◽  
The Impact

Nimonic C-263 is predominantly used in the manufacturing of heat susceptible intricate components in the gas turbine, aircraft, and automotive industries. Owing to its high strength, poor thermal conductivity, the superalloy is difficult to machine and causes rapid tool wear during conventional machining mode. Moreover, the unpleasant machining noise produced during machining severely disrupts the tool engineer’s concentration, thereby denying a precise and environment friendly machining operation. Hence, close dimensional accuracy, superior machined surface quality along with production economy, and pleasant work environment for the tool engineers is the need of an hour of the current manufacturing industry. To counter such issues, the present work attempts to compare and explore the machinability of two of the most popular machining strategies like minimum quantity lubrication (MQL) and cryogenic machining process during turning of Nimonic C-263 work piece in order to achieve an ideal machining environment. The machining characteristics are compared in terms of surface roughness (SR), power consumption (P), machining noise (S), nose wear (NW), and cutting forces (CF) to evaluate the impact of machining variables like cutting speed (Vc), feed (f), and depth of cut (ap) with a detailed parametric study and technical justification. Yet again, an investigation is conducted to compare both the machining strategies in terms of qualitative responses like chip morphology, total machining cost, and carbon emissions. The study revealed that cryogenic machining strategy is adequately proficient over MQL machining to deliver energy proficient and gratifying work environment for the tool engineers by reducing the cost of machining and improving their work efficiency.

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