Design and Analysis of Disturbance Force Observer for Machine Tools Application

2015 ◽  
Vol 761 ◽  
pp. 148-152
Author(s):  
J. Jamaludin ◽  
Zamberi Jamaludin ◽  
T.H. Chiew ◽  
Lokman Abdullah
Keyword(s):  
Cutting Force ◽  
System Performance ◽  
Machine Tools ◽  
Material Removal ◽  
External Disturbance ◽  
Milling Process ◽  
Frequency Content ◽  
Positioning Accuracy ◽  
Fast Fourier Transform Analysis

In milling process, the quality of tracking performance is influenced by the characteristics of the cutting forces generated during the material removal process. The undesired frequency harmonics of the cutting force contributes negatively to the positioning accuracy. An effective compensation of these harmonics is desired. This paper presents and discusses a disturbance force observer as an approach to estimate and compensate effect of external disturbance forces on system performance. Knowledge of the properties of the disturbance signal is essential for the design of an observer. A Fast Fourier Transform analysis of the disturbance force reveals the harmonics content of the signal. The frequency harmonics is a function of the spindle rotational speeds. The results show effective compensation of the cutting force with reduced amplitudes of the harmonics frequency content.

Machining a Micro-Scale Structure Using an in-House Developed Miniature Machine Tool

2011 ◽  
Vol 418-420 ◽  
pp. 1502-1506
Author(s):  
Abdul Shukor Syaimak
Keyword(s):  
Surface Quality ◽  
Machine Tools ◽  
Milling Process ◽  
Micro Milling ◽  
Batch Size ◽  
End Mill ◽  
Geometrical Accuracy ◽  
Custom Made ◽  
Solid Carbide

Custom-built Miniature Machine Tools (MMTs) are now becoming more popular with the demand for reduced energy consumption and workshop floor when machining small/medium batch size micro-components. This paper investigates the capability of a custom-built 4-axis MMT through machining a micro-component demonstrator. The experiments have been carried out in Titanium Alloyed (TiAL6V4) using 0.6mm solid carbide flat end mill cutters. From here, the surface quality and geometrical accuracy of the machined testpiece are evaluated and analysed. The investigation has shown that acceptable geometrical accuracies and surface quality of the machined micro-demonstrator can be achieved using the in-house developed MMT. These results show that the use of the custom-made MMT does not hinder the micro-milling process to produce a good and satisfactory surface quality and acceptable geometrical accuracy.

scholarly journals ANALYSIS OF PARAMETERS AFFECTING THE QUALITY OF A CUTTING MACHINE

2014 ◽  
Vol 54 (1) ◽  
pp. 63-67
Author(s):  
Iveta Onderová ◽  
Lubomír Šooš
Keyword(s):  
Machine Tools ◽  
Qualitative Evaluation ◽  
Fem Analysis ◽  
Technological Parameters ◽  
Positioning Accuracy ◽  
Linear Motors ◽  
Cutting Machine ◽  
Innovative Solution ◽  
Linear Synchronous Motors

The quality of cutting machines is affected by several factors that can be directly or indirectly influenced by manufacturers, technicians and users of machine tools. The most critical qualitative evaluation parameters of machine tools include accuracy and stability. Investigations of accuracy and repeatable positioning accuracy were essential for the research presented in this paper. The aim was to develop and experimentally verify the design of a methodology for cutting centers aimed at achieving the desired working precision. Before working on the topic described here, it was necessary to make several scientific analyses, which are summarized in this paper. We can build on the initial working hypothesis that by improving the technological parameters (e.g. by increasing the working speed of the machine, or by improving the precision of the positioning) the quality of the cutting machine will also be improved. For the purposes of our study, several investigated parameters were set affecting positioning accuracy, such as rigidity, positioning speed, etc. First, the stiffness of the portal structure of the cutting machine was analyzed. FEM analysis was used to investigate several alternative structures of the cutting machine, and also an innovative solution for beam mounting. The second step was to integrate two types of drives into the design of the cutting machine. The first drive is a classic rack and pinion drive for cutting machines. To increase (improve) the working speed of the machine, linear motors were designed as an alternative drive. The portal of the cutting machine was designed for a working speed of 260mmin−1 and acceleration of 25 m. s−2. The third step was based on the results of the analysis. In collaboration with Microstep, an experimental cutting machine in a portal version was produced using linear synchronous motors driving the portal on both sides, and with direct linear metering of its position. In the fourth step, an experiment was designed and conducted to explore the positioning accuracy and the repeatable positioning accuracy.

Improvement of cutting force and material removal rate for disc milling TC17 blisk tunnels using GRA–RBF–PSO method

2019 ◽  
Vol 233 (16) ◽  
pp. 5556-5567
Author(s):  
Nan Zhang ◽  
Yaoyao Shi
Keyword(s):  
Cutting Force ◽  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Rbf Neural Network ◽  
Cutting Speed ◽  
Pso Algorithm ◽  
Milling Process ◽  
Aero Engines ◽  
Cutting Height

Blisk is a key component of new aero-engines. To improve machining efficiency, disc milling is used for roughing blisk tunnels. The multi-objective optimization is employed to optimize disc milling process. In this study, an integration-based approach that used grey relational analysis (GRA) coupled with radial basis function (RBF) neural network and particle swarm optimization (PSO) algorithm is applied to solve the optimization problem. To achieve smaller cutting force and greater material removal rate (MRR), the appropriate cutting speed, feed rate per tooth, and cutting height needed to be determined. A hybrid experiment scheme of three factors–five levels is carried out to generate data sample. Results of verified experiments indicate that GRA–RBF–PSO approach can improve performance better than original GRA.

scholarly journals Comparison of different mathematical models for prediction of self-excited vibrations occurance in milling process

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Aleksandar Kosarac ◽  
Cvijetin Mladjenovic ◽  
Milan Zeljkovic ◽  
Lana Sikuljak
Keyword(s):  
Machine Tools ◽  
Metal Cutting ◽  
Influencing Factor ◽  
Mechanical Vibration ◽  
Decisive Role ◽  
Milling Process ◽  
Stability Lobe ◽  
Excited Vibration ◽  
Stability Lobe Diagrams

In modern production, despite the existence of other production methods, metal cutting still plays an important role. The performance of machine tools has a decisive role in terms of productivity and quality of production increase. Undoubtedly, productivity and quality of production are two mail requirements which are key elements to stay on top in a competitive market. One of the most influencing factor that affect the machine tools are vibrations. The most unwanted vibrations that can appear during metal cutting process are self-excited vibrations, which are one of the three kinds of mechanical vibration, free vibration, forced vibration, and self-excited vibration. When it comes to improving the performance of machine tools, the analysis of the appearance of self-excited vibrations and their isolation occupy a significant place. The aim of this paper derives from trends and limitations exists in metal production. The way to isolate the self-excited vibrations is to predict their occurrence by defining the stability lobe diagram. The paper presents two popular analytical methods for identifying stability lobe diagrams in milling, which shows the boundary between stable and unstable zone of machining operations, depending on the number of revolutions of the spindle and cutting depth. First considered method is Fourier series approach and second one id average tooth angle approach. Lather, both stability lobe diagrams were compared with results obtained experimentally.

FEM-Based Simulation for Workpiece Deformation in Thin-Wall Milling

2015 ◽  
Vol 9 (2) ◽  
pp. 122-128 ◽  
Author(s):  
Jun Wang ◽  
◽  
Soichi Ibaraki ◽  
Atsushi Matsubara ◽  
Kosuke Shida ◽  
...  
Keyword(s):  
Cutting Force ◽  
Material Removal ◽  
Oblique Line ◽  
Milling Process ◽  
Cutting Edge ◽  
Time Interval ◽  
Thin Wall ◽  
Constant Cutting Force ◽  
Cutting Experiments

This paper focuses on the deformation of a thin wall during the milling process. Cutting experiments were performed to investigate the influence of the workpiece thickness on its deformation and the cutting force. An FEM-based model was developed to simulate the deformation of a thin-wall workpiece during the milling process. With a tool’s rotation, the cutting force is distributed along the helical cutting edge, and the workpiece deformation can be calculated for a given time interval. The simulated results were compared with those of a simpler model where a constant cutting force is uniformly distributed along an oblique line representing the material removal by a cylindrical tool. Finally, the application of these results to the design of ribs for thin-wall parts during machining was considered.

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.

Dynamics of the processes in metal machining

1998 ◽  
Vol 2 ◽  
pp. 115-122
Author(s):  
Donatas Švitra ◽  
Jolanta Janutėnienė
Keyword(s):  
High Frequency ◽  
Machine Tools ◽  
Metal Cutting ◽  
Cutting Tool ◽  
Low Frequency ◽  
Metal Cutting Machine ◽  
Cutting Machine ◽  
Metal Machining

In the practice of processing of metals by cutting it is necessary to overcome the vibration of the cutting tool, the processed detail and units of the machine tool. These vibrations in many cases are an obstacle to increase the productivity and quality of treatment of details on metal-cutting machine tools. Vibration at cutting of metals is a very diverse phenomenon due to both it’s nature and the form of oscillatory motion. The most general classification of vibrations at cutting is a division them into forced vibration and autovibrations. The most difficult to remove and poorly investigated are the autovibrations, i.e. vibrations arising at the absence of external periodic forces. The autovibrations, stipulated by the process of cutting on metalcutting machine are of two types: the low-frequency autovibrations and high-frequency autovibrations. When the low-frequency autovibration there appear, the cutting process ought to be terminated and the cause of the vibrations eliminated. Otherwise, there is a danger of a break of both machine and tool. In the case of high-frequency vibration the machine operates apparently quiently, but the processed surface feature small-sized roughness. The frequency of autovibrations can reach 5000 Hz and more.

О ТОЧНОСТИ ОПРЕДЕЛЕНИЯ КООРДИНАТ ПОДВОДНОГО МОДУЛЯ НА ОСНОВЕ ИЗМЕРЕННЫХ ПАРАМЕТРОВ ДВИЖЕНИЯ БУКСИРУЕМОЙ СИСТЕМЫ

2020 ◽  
Author(s):  
V.V. Kostenko ◽  
Yu.V. Vaulin ◽  
F.S. Dubrovin ◽  
O.Yu. Lvov
Keyword(s):  
Immersion Depth ◽  
Computational Algorithms ◽  
Navigation Systems ◽  
Short Baseline ◽  
Positioning Accuracy ◽  
Underwater Acoustic ◽  
Ground Speed ◽  
Cable Length ◽  
Acoustic Navigation

Буксируемый подводный модуль (БПМ) эффективно используется для решения задач, связанных с координированием подводных объектов, местоположение которых подлежит уточнению в процессе их детальногообследования. При этом большое значение имеет точность определения координат самого буксируемогомодуля относительно судна-буксировщика. Использование гидроакустических навигационных средств, вчастности систем с ультракороткой базой (ГАНС УКБ), ограничено вследствие помех, влияющих на качествосигналов в приемной антенне. Альтернативой служит метод определения координат БПМ на основе данныхтраекторных измерений параметров буксируемой системы. К числу последних относятся расчетные значенияпараметров кабеля связи в установившихся режимах буксировки, значения путевой скорости и путевого углабуксировщика, а также измеренные значения длины кабеля, глубины погружения и курса БПМ. В работе дансравнительный анализ различных вариантов вычислительных алгоритмов, позволяющих получить оценки точности определения координат БПМ в различных режимах стационарной буксировки и при наличии сбоев вработе навигационных средств.The towed underwater module (TUM) is a useful toolfor solving problems of the positioning of the underwaterobjects, the location of which must be clarified during its detailedinspection. Herewith, the accuracy of the determinationof the coordinates of the towed module itself relative tothe towing vessel is essential for such kind of problems. Theuse of underwater acoustic navigation means, the systemswith ultra-short baseline (USBL) in particular, are limiteddue to interference affecting the quality of the signals on thereceiving antenna. As an alternative, the method is proposedfor TUM positioning based on trajectory measurements ofparameters of the towed system, which may include calculatedvalues of communication cable parameters in steadystatetowing modes, values of ground speed and towing angle,as well as measured cable length, immersion depth, andTUM heading. The paper provides a comparative analysisof various versions of computational algorithms, which allowobtaining estimates of the TUM positioning accuracy indifferent modes of stationary towing and in the presence offailures in navigation systems operation.

scholarly journals Control of an IPMC Soft Actuator Using Adaptive Full-Order Recursive Terminal Sliding Mode

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 33
Author(s):  
Romina Zarrabi Ekbatani ◽  
Ke Shao ◽  
Jasim Khawwaf ◽  
Hai Wang ◽  
Jinchuan Zheng ◽  
...  
Keyword(s):  
Sliding Mode ◽  
External Disturbance ◽  
Tracking Error ◽  
Working Environment ◽  
Parametric Uncertainties ◽  
Metal Composite ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Positioning Accuracy ◽  
Soft Actuator

The ionic polymer metal composite (IPMC) actuator is a kind of soft actuator that can work for underwater applications. However, IPMC actuator control suffers from high nonlinearity due to the existence of inherent creep and hysteresis phenomena. Furthermore, for underwater applications, they are highly exposed to parametric uncertainties and external disturbances due to the inherent characteristics and working environment. Those factors significantly affect the positioning accuracy and reliability of IPMC actuators. Hence, feedback control techniques are vital in the control of IPMC actuators for suppressing the system uncertainty and external disturbance. In this paper, for the first time an adaptive full-order recursive terminal sliding-mode (AFORTSM) controller is proposed for the IPMC actuator to enhance the positioning accuracy and robustness against parametric uncertainties and external disturbances. The proposed controller incorporates an adaptive algorithm with terminal sliding mode method to release the need for any prerequisite bound of the disturbance. In addition, stability analysis proves that it can guarantee the tracking error to converge to zero in finite time in the presence of uncertainty and disturbance. Experiments are carried out on the IPMC actuator to verify the practical effectiveness of the AFORTSM controller in comparison with a conventional nonsingular terminal sliding mode (NTSM) controller in terms of smaller tracking error and faster disturbance rejection.

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