International Journal of Mechatronics and Manufacturing Systems (13 papers in press)
Solution method of the kinematic function scheme for reconfigurable machine tools based on kinematic transformation
by Guodong Yi, Ye Gu, Shuyou Zhang
Abstract: The kinematic function scheme is the basis of the reconfigurable machine tool (RMT) design. However, the diversity and complexity of the scheme are not conducive to the realization of reconfiguration. To solve this problem, this paper proposes a solution method of the kinematic function scheme based on kinematic transformation. A tool-feature pose matrix is established based on an analysis of the relationship between machining surface features and machining tools to obtain a kinematic function expression that shows the kinematic requirements of the machine tool. The kinematic feature domain and the kinematic transformation domain are used to describe the motion type, motion direction and other information to describe the kinematic parameters of the module. The solution method of the kinematic function chain based on the kinematic decomposition and module combination is proposed to establish the kinematic function scheme of a RMT.
Keywords: reconfigurable machine tool; kinematic function scheme; tool-feature pose matrix; kinematic function expression; module; kinematic transformation; kinematic function chain.
Effect of grinding depth on surface topography by considering vibrations and a force prediction model
by Mingxia Kang, Lu Zhang, Wencheng Tang
Abstract: Little consideration has been given to vibrations when the effect of grinding process parameters on the surface morphology is studied. Taking a grinding force as the intermediate variable, influences of grinding depths on the surface topography are investigated more accurately with considering vibrations in this paper. Firstly, a novel grinding force prediction model is proposed through amending the Malkin model by integrating with contact arc length and abrasive grain contact angle two factors. Secondly, vibrations of the feed platform and the grinding wheel shaft are analyzed by means of threshold filtering and median filtering. It is found that the vibration displacement in the x-direction of the wheel axis remains substantially between 140-150 nm, while in the y-direction, it increases with the grinding depth. Finally, three-dimensional surface topographies with different grinding depths are investigated. It is observed that the deeper crack, more pronounced defects and a coarse texture are gradually generated as the grinding depth increases. And parameters like Sa, Sq, Sku, Ssk are more representative of the real grinding quality of workpiece surface than Ra, Rq, Rsk, Rku.
Keywords: contact arc length; abrasive grain contact angle; grinding force; surface topography; vibrations.
Statistical analysis of the parameters in SPIF/DPIF in the thickness reduction in an experimental geometry
by Ferney-Alexis Giraldo-Castrillon, Yessica-Maria Giraldo-Castrillon, Gabriel-Jaime Paramo-Bermúdez
Abstract: The objective of the present study was to determine the thickness reduction during the incremental deformation process with two techniques: SPIF/DPIF. A geometric structure was built using software (CAD), and the paths simulated in a software (CAM). Experimental design of a full factorial type was made 2^3, for each technique, eight simulations, and three replicas. The variables studied in each experiment were the wall angle, the depth increase and the diameter of the tool. The three parameters are associated with the incremental deformation, although the angle was the most influential and the interaction between them in both techniques was significant. There was no difference in the comparative analysis between the different points in which the reduction of the thickness measured, just as neither one technique showed to be superior to the other. The angle of 68
Keywords: metadata,incremental forming; SPIF; DPIF; design of experiments; CAD; CAM; dieless.
Experimental investigation in Photochemical Machining process through Response Surface Methodology for manufacturing of micro mould
by Devendra Agrawal
Abstract: Photochemical Machining (PCM) is used as one of the best micromachining technique for machining of difficult-to-cut material with appropriate machining parametric combinations. Ferric chloride is used as etchant for machining of Stainless Steel-304.In the present study, the effect of process parameters such as time of etching, temperature of etchant and concentration of etchant on Material Removal Rate (MRR), Surface roughness (Ra), Undercut (Uc) and Etch Factor (EF) in PCM of SS-304 is evaluated by using Response Surface Methodology (RSM) and the optimum machining condition is evaluated. The Central Composite Design (L20) is used to understand the behavior of responses with change in levels of machining parameters. The optimum machining parameters evaluated are temperature of etchant at 54.65oC, time of etching at 47.14 min. and concentration of etchant at 727.80 g/l. The confirmatory result shows the improvement in performance quality with setting of machining parameter at optimum level. The optimum machining parameters are used to manufacture the array of micro mould with size of 139
Keywords: PCM; Etching; Phototool; Undercut; MRR; RSM; Micro mould.
Modeling of MRR and hole taper for ultrasonic assisted jet electrochemical micro-drilling process using Buckinghams theorem
by Harsha Goel, Usharani Rath, Pulak Mohan Pandey
Abstract: Ultrasonic assisted jet-electrochemical micro-drilling (UAJet-ECMD) process integrates ultrasonic vibrations and jet electrochemical micro drilling process. In the present study, Buckinghams π theorem has been employed to model the process responses namely material removal rate (MRR) and hole taper of the UAJet-ECMD process with continuous DC voltage. The model has been formulated taking into account the experimental parameters namely voltage, electrolyte concentration, electrolyte pressure, inter electrode gap, pulse on time of ultrasonic vibrations and other physical properties related to ultrasonic vibrations such as speed of ultrasonic waves in the electrolyte, amplitude and frequency of ultrasonic vibrations. Electrochemical properties of work piece material namely chemical equivalent of copper and Faradays constant were also taken into considerations. The use of regression analysis has been done to model the process responses. From the resultant π terms contained in the developed models, insignificant terms based on their percentage contributions were reduced and the models for both MRR and hole taper were modified. The formulated models for MRR and hole taper were validated with the statistical models obtained from experimental results.
Keywords: Buckingham’s π theorem; Jet-Electrochemical; Hole taper; Material removal rate; Micro drilling; Ultrasonic vibrations.
Micro textured cutting tool effects on cutting forces, volumetric wear and adhesion in dry turning of titanium alloy
by Tugrul Özel
Abstract: There are several distinct advantages offered by micro-textures applied to cutting tool surfaces to reduce forces, friction, and wear. This study provides investigations on micro-grooves fabricated on the rake face of tungsten carbide inserts (WC/Co) that were used in turning titanium alloy Ti-6Al-4V under dry conditions. Tool inserts included varying micro-groove width (50 ~100 m), depth (10 ~ 30 m) and spacing (15 ~ 100 m). In the experiments, a constant depth of cut and a cutting speed were used. The effect of micro-textured tool surfaces on cutting force and tool wear was found to be significant.
Keywords: Cutting tool; machining; micro-texture.
Cutting force investigation in face milling of additively fabricated nickel alloy 625 via powder bed fusion
by Jixiong Fei, Kaushalendra Patel, Guoliang Liu, Tugrul Özel
Abstract: The face milling of additively fabricated nickel alloy 625 produced via laser powder bed fusion is experimentally investigated. Typically, cutting forces are the most important factor affects the process outcome in terms of surface finish and chatter vibrations in milling of difficult-to-cut materials. The additively fabricated materials possess different mechanical properties hence their cutting force performance is usually unknown. For additively fabricated nickel alloy 625, the build direction and scan strategy rotation are known to influence the resultant workpiece structure with columnar grains. The peak milling force is found dependent upon the feed direction as well as the layerwise scan rotation employed in fabricating the workpiece. Feeding the cutter against the build direction resulted in lower peak forces with larger deviations, however feeding along the build direction resulted in higher peak forces with lower deviations. The build direction was also observable on fan shaped chip surfaces.
Keywords: Additive Manufacturing; Milling; Force; Nickel.
Special Issue on: From the Members of the Editorial Board
Comparison of Model Free Control Strategies for Chatter Suppression by an Inertial Actuator
by Iker Mancisidor, Alexander Pena-Sevillano, Rafael Barcena, Oier Franco, Jokin Munoa, Luis Norberto Lopez de Lacalle
Abstract: The employment of inertial active damping devices for chatter suppression in machining processes has been widely studied. The main drawback is that machine tools generally offer reduced spaces for the actuator location close to the cutting point and, hence, a reduced volume design is required for this external device. Consequently, the ratio between the force capability and the occupied volume is of major importance. Therefore, the performance of the actuator must be exploited to the fullest, which depends principally on the selected control strategy to determine the force to be exerted. The work presents the comparison of the most used feedback control algorithms and a novel strategy based on the regenerative effect disturbance. Their results are assessed for orthogonal cutting cases, with the aim of optimizing the behavior of the active damping system.
Keywords: active damping; inertial actuator; chatter
Development of a portable stereolithography device for computer numerical control machining centers
by Vasileios Sergis, George-Christopher Vosniakos
Abstract: A low-cost portable stereolithography (SLA) device is designed to cure polymer resin at suitable laser light wavelength. Required motions are imparted by any three-axis CNC machining center exploiting serial communication interface, macro programming and machine data manipulation facilities. The device consists of three subsystems: laser beam, resin handling and micro-controller, making use of several sensors and actuators. For an approximately circular beam spot the G-code is generated by commercially available slicing software and is automatically modified to comply with the CNC machine controller’s own automation functions. Alternatively, for line-shaped laser beams G-code can be directly generated from STL files by making use of profiling and hatching library routines. The device has been tested with two different power diode lasers for manufacturing a variety of parts. Curing rate was tested by microhardness measurement. Dimensional accuracy with respect to nominal was recorded using a white-light scanner, proving that acceptable accuracy is reachable.
Keywords: Additive Manufacturing; Stereolithography; photopolymers; CNC; machining center; micro-controller; g-code macros
Ultrasonic-assisted machining processes: A review
by Uday Shanker Dixit, Pulak Mohan Pandey , Girish Chandra Verma
Abstract: Ultrasonic-assisted machining process is one of the most recently explored hybrid machining processes. In ultrasonic assisted machining process, an oscillating motion (of small amplitude and high frequency) is superimposed on the conventional machining operation. The assistance of ultrasonic vibrations in machining process improves the performance of the process by reducing cutting forces and enhancing surface quality. The effect of ultrasonic vibration has been found very beneficial in different conventional and non-conventional machining processes. This paper reviews the analytical and experimental studies in the area of ultrasonic-assisted turning, milling and drilling, respectively. Additionally, the effect of ultrasonic vibration on non-conventional machining processes is also reviewed. The paper also explains the effect of ultrasonic vibration on the cutting mechanics. The research gaps present in the ultrasonic-assisted machining process domain have also been highlighted in order to drive on the path of future research in this area.
Keywords: ultrasonic-assisted machining process; ultrasonic-assisted turning; ultrasonic-assisted milling; ultrasonic-assisted drilling; hybrid machining; ultrasonic-assisted grinding; cutting force; surface roughness; vibrations; cutting temperature.
Data-driven productivity improvement in machinery supply chains
by Lorenz Rafael, Torbjørn H. Netland, Philip Roh, Valentin Holzwarth, Andreas Kunz, Konrad Wegener
Abstract: Modern manufacturing machines are equipped with numerous sensors that collect a large amount of various data. This data can be used to improve the machines’ productivity. Both the users and suppliers of machines could benefit from such opportunities. However, because machine users risk the loss of intellectual property, they are often reluctant to share their data. This represents a major inhibitor of data sharing in machinery supply chains. This paper proposes a five-step method for initialising data sharing between machine users and their machine suppliers. The method was tested and validated in a case company, and the potential benefits for machine users were quantified.
Keywords: Data sharing; Remote Services; Smart Machining Systems; Product-Service-Systems.
Meshless Single Grain Cutting Simulations on the GPU
by Matthias Röthlin, Hagen Klippel, Mohamadreza Afrasiabi, Konrad Wegener
Abstract: Physically sound prediction of grinding results necessarily starts with the single grain interaction with the material, which is especially important for engineered grinding tools (EGT). The deformations encountered in single grain simulations are severe, especially due to the large negative rake angles. Conventional software tools using FEM suffer from the induced extreme distortions of the grid, necessitating costly remeshing operations. Meshless methods are not limited in the amount of deformation they can reproduce and thus a promising alternative, which also has the potential for extreme parallelization on the graphics co-processor (GPU). With the drastically increased computational speed unprecedented simulation resolutions can be achieved at reasonable computation times allowing parameter studies on different friction and constitutive models with first order complete meshless formulations.
Keywords: Meshless Methods, GPGU Computing, Simulation, Metal Cutting, Grinding, Engineered Grinding Tools, Smoothed Particle Hydrodynamics, Particle Methods, CUDA, Open Source
Robust Trajectory Control of an Unmanned Aerial Vehicle Using Acceleration Feedback
by Hammad Zaki, Gokhan Alcan, Mustafa Unel
Abstract: In this work, acceleration feedback is utilized in a hierarchical control structure for robust trajectory control of a quadrotor helicopter subject to external disturbances where reference attitude angles are determined through a nonlinear optimization algorithm. Furthermore, an acceleration-based disturbance observer (AbDOB) is designed to estimate disturbances acting on the positional dynamics of the quadrotor. For the attitude control, nested position, velocity, and inner acceleration feedback loops consisting of PID and PI type controllers are developed to provide high stiffness against external disturbances. Reliable angular acceleration is estimated through a cascaded filter structure. Simulation results show that the proposed controllers provide robust trajectory tracking performance when the aerial vehicle is subject to wind gusts generated by the Dryden wind model along with the uncertainties and measurement noise. Results also demonstrate that the reference attitude angles calculated through nonlinear optimization are smooth and within the desired bounds.
Keywords: robust control; acceleration feedback; disturbance observer; quadrotor; hierarchical control; nonlinear optimization