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Article

Lie Yu, Jianbin Zheng, Yang Wang, Enqi Zhan and Qiuzhi Song

The purpose of this paper is to present a direct force control which uses two closed-loop controller for one-degree-of-freedom human-machine system to synchronize the…

Abstract

Purpose

The purpose of this paper is to present a direct force control which uses two closed-loop controller for one-degree-of-freedom human-machine system to synchronize the human position and machine position, and minimize the human-machine force. In addition, the friction is compensated to promote the performance of the human-machine system.

Design/methodology/approach

The dynamic of the human-machine system is mathematically modeled. The control strategy is designed using two closed-loop controllers, including a PID controller and a PI controller. The frictions, which exist in the rotary joint and the hydraulic wall, are compensated separately using the Friedland’s observer and Dahl’s observer.

Findings

When human-machine system moves at low velocity, there exists a significant amount of static friction that hinders the system movements. The simulation results show that the system gives a better performance in human-machine position synchronization and human-machine force minimization when the friction is compensated.

Research limitations/implications

The acquired results are based on simulation not experiment.

Originality/value

This paper is the first to apply the electrohydraulic servo systems to both actuate the human-machine system, and use the direct force control strategy consisting of two closed-loop controllers. It is also the first to compensate the friction both in the robot joint and hydraulic wall.

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Article

Shouyan Chen and Tie Zhang

The purpose of this paper is to reduce the strain and vibration during robotic machining.

Abstract

Purpose

The purpose of this paper is to reduce the strain and vibration during robotic machining.

Design/methodology/approach

An intelligent approach based on particle swarm optimization (PSO) and adaptive iteration algorithms is proposed to optimize the PD control parameters in accordance with robotic machining state.

Findings

The proposed intelligent approach can significantly reduce robotic machining strain and vibration.

Originality value

The relationship between robotic machining parameters is studied and the dynamics model of robotic machining is established. In view of the complexity of robotic machining process, the PSO and adaptive iteration algorithms are used to optimize the PD control parameters in accordance with robotic machining state. The PSO is used to optimize the PD control parameters during stable-machining state, and the adaptive iteration algorithm is used to optimize the PD control parameters during cut-into state.

Details

Industrial Robot: An International Journal, vol. 45 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

S. Vishnupriyan

Source errors in a workpiece fixture system include the compliance of the workpiece fixture system and workpiece dynamics. The purpose of this paper is to study the…

Abstract

Purpose

Source errors in a workpiece fixture system include the compliance of the workpiece fixture system and workpiece dynamics. The purpose of this paper is to study the relative significance of these two. The findings would help to achieve computational economy in optimization of fixture layout and/or clamping forces.

Design/methodology/approach

Different layouts are generated with the help of a reconfigurable fixture set up and a slot is end milled on the workpiece. Using these data and the finite element software ANSYS, the machining error due to system compliance is computed. The machining error due to workpiece dynamics is obtained using a data acquisition system with the LabView software. These steps are repeated for different clamping forces and the relative contribution of these two sources to the overall machining error is studied.

Findings

Results show that the system compliance is much smaller in magnitude compared to workpiece dynamics and hence does not contribute appreciably to the overall machining error. This leads to the conclusion that, for bulky and stiff parts, evaluation of the machining error due to compliance can be done away with.

Originality/value

The paper's originality lies in comparing the two sources of machining error using experimental work and finite element models. To the author's knowledge such a comparison has not been reported in the literature.

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Article

Imen Abdennadher and Ahmed Masmoudi

The paper is aimed at the investigation of the magnetic forces generated by fractional slot surface mounted PM machines, considering a comparative study between two…

Abstract

Purpose

The paper is aimed at the investigation of the magnetic forces generated by fractional slot surface mounted PM machines, considering a comparative study between two topologies: a 9 slot/10 pole machine and a 12 slot/10 pole machine.

Design/methodology/approach

Following the distribution of the armature windings using the star of slots approach, an investigation of the magnetic forces developed by both machines under study, using 3D finite element analysis (FEA). Prior to such investigation, a 2D FEA based sizing procedure is carried out in order to select a set of suitable geometrical parameters. Then, the comparison between both machines is extended to the torque production capability.

Findings

It has been found that the 9 slot/10 pole machine has a pic value of the average magnetic force reaching almost 40N which is located in one side of the air gap. Such a peak does not exceed 7N in the 12 slot/10 pole machine and is located in two diametrically‐opposite areas of the air gap.

Research limitations/implications

This work should be extended by an experimental validation of the FEA results regarding the magnetic force generation.

Practical implications

The list of the selection criteria of fractional slot PM machines should be extended to the magnetic force generation in order to fulfil the requirements of many applications such as the propulsion systems.

Originality/value

The paper proposes a combined electromagnetic‐mechanical approach to investigate the magnetic forces generated by fractional slot surface mounted PM machines using 2D and 3D finite element analysis.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 32 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

A.G.F. Alabi, T.K. Ajiboye and H.D. Olusegun

Developing countries are now fully aware of the importance of the manufacturing sector as a key factor of growth and transformation of their economy. Improved technology…

Abstract

Purpose

Developing countries are now fully aware of the importance of the manufacturing sector as a key factor of growth and transformation of their economy. Improved technology and method of manufacturing have produced quality products at reduced cost and this has advanced development. The study uses experimental methods based on orthogonal cutting process to measure the cutting forces using a dynamometer while machining the test specimen with a diamond cutting tool at 5° rake angle. The machining forces for the dry cutting are higher than the wet cutting in the range of 31.2‐44.31, 32.09‐40.67, 29.10‐35.62, 29.21‐45.03 and 29.94‐38.74 percent for “as received”, normalized, tempered, annealed and hardened specimen, respectively. For annealed and hardened test specimen, the cutting speed of 245 rpm is ideal for machining when it gives a fine surface finish. Also for precision machining, dry turning is by far a better cost saver and cleaner option than wet turning. This is because though wet machining is relatively more expensive, it is hazardous to health. Normalized and annealed specimens require lower cutting forces and chip formation is slow. Tempering and annealing medium carbon steel facilitated rapid machining and chip formation is rapid. It is therefore an advantage to temper or anneal medium carbon steel before processing into component parts in the manufacturing industry as it saves cost and gives fine component surface finish. The paper aims to address these issues.

Design/methodology/approach

Tensile samples are prepared from medium carbon steel. These prepared samples were later subjected to heat‐treatment operations (normalizing, hardening, tempering and annealing). Tensile test were carried out to obtain the materials' sensitive properties used in the modeling equations. An experimental method based on orthogonal cutting is adopted to measure the machining forces using techquipment dynamometer.

Findings

It is observed that as tu increases, Fc increases for all conditions, i.e. as tu increases, tool‐chip contact area increases and increasing frictional force, also volume of metal removal increase resulting in increasing energy input. Fc values is highest for the normalized followed by that of the annealed. They are less for hardened and tempered. This is because of the mode of chip formation whereby ductile structures give continuous chips as against discontinuous structure for the hardened and quenched structures. Input energy is high for the former and low for the later. This is confirmed by the m values and observed chips.

Research limitations/implications

There is no limitation, except for the instrumentation. On availability of the appropriate equipment, like the Kystler dynamometer for the correct reading of the experimental results.

Practical implications

The implication is limited to the workshop hazard during the experiment.

Originality/value

The research work is original.

Details

Journal of Engineering, Design and Technology, vol. 8 no. 1
Type: Research Article
ISSN: 1726-0531

Keywords

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Article

M.P. Jenarthanan, Venkata Sai Sunil Gujjalapudi and Venkatraman V.

The purpose of this paper is to originate a statistical model for delamination factor, surface roughness, machining force and also to determine and compare the effects of…

Abstract

Purpose

The purpose of this paper is to originate a statistical model for delamination factor, surface roughness, machining force and also to determine and compare the effects of machining parameters (spindle speed, fiber orientation angle, helix angle and feed rate) on the output responses during end-milling of glass fiber reinforced polymers (GFRP) by using desirability functional analysis (DFA) and grey relational analysis (GRA).

Design/methodology/approach

Based on Taguchi’s L27 orthogonal array, milling experiments were carried on GFRP composite plates employing solid carbide end mills with different helix angles. The machining parameters were optimized by an approach based on DFA and GRA, which were useful tools for optimizing multi-response considerations, namely, machining force, surface roughness and delamination factor. A composite desirability index was obtained for multi-responses using individual desirability values from DFA. Based on this index and grey relational grade the optimum levels of parameters were identified and significant contribution of parameters was ascertained by analysis of variance.

Findings

Fiber orientation angle (66.75 percent) was the significant parameter preceded by feed rate (15.05 percent), helix angle (7.76 percent) and spindle speed (0.30 percent) for GFRP composite plates.

Originality/value

Multi-objective optimization in end-milling of GFRP composites using DFA and GRA has not been performed yet.

Details

Multidiscipline Modeling in Materials and Structures, vol. 13 no. 3
Type: Research Article
ISSN: 1573-6105

Keywords

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Article

M.P. Jenarthanan, R. Gokulakrishnan, B. Jagannaath and P. Ganesh Raj

The purpose of this paper is to find out the optimum machining parameters using Taguchi technique with principal component analysis (PCA) during end milling of GFRP composites.

Abstract

Purpose

The purpose of this paper is to find out the optimum machining parameters using Taguchi technique with principal component analysis (PCA) during end milling of GFRP composites.

Design/methodology/approach

In multi-objective optimization, weight criteria of each objective are important for producing better and accurate solutions. This method has been employed for simultaneous minimization of surface roughness, cutting force and delamination factor. Experiments were planned using Taguchi’s orthogonal array with the machining parameters, namely, helix angle of the end mill cutter, spindle speed, feed rate and depth of cut were optimized with considerations of multiple response characteristics, including machining force, surface roughness and delamination as the responses. PCA is adopted to find the weight factors involved for all objectives. Finally analysis of variance concept is employed on multi-SN ratio to find out the relative significance of machining parameter in terms of their percentage contribution.

Findings

The multi-SN ratio is achieved by the product of weight factor and SN ratio to the performance characteristics in the utility concept. The results show that a combination of machining parameters for the optimized results has helix angle of 35°, machining speed of 4,000 m/min, feed rate of 750 mm/rev and depth of cut of 2.0 mm.

Originality/value

Effect of milling of GFRP composites on delamination factor, surface roughness and machining force with various helix angle solid carbide end mill has not been analysed yet using PCA techniques.

Details

Multidiscipline Modeling in Materials and Structures, vol. 13 no. 1
Type: Research Article
ISSN: 1573-6105

Keywords

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Article

Bernhard Weilharter, Oszkár Bíró and Siegfried Rainer

The purpose of this paper is to analyse the surface vibrations of an induction machine due to force waves acting on the stator and rotor core. The focus lies on the…

Abstract

Purpose

The purpose of this paper is to analyse the surface vibrations of an induction machine due to force waves acting on the stator and rotor core. The focus lies on the investigation of the influence of force waves with axial variation and with higher spatial ordinal numbers on the surface vibration of an induction machine and thus its emitted noise.

Design/methodology/approach

Unit force waves with different spatial ordinal numbers and varying in axial direction are set up and applied on the stator and rotor teeth of a structural finite element model of an induction machine. Structural harmonic analyses with different frequencies are performed and the deformation of the machine is determined. After that, the root mean square of the normal component of the velocity on the surface of the machine's housing is determined and compared for the different force waves.

Findings

The influence of force waves with spatial ordinal numbers of higher order can have a significant influence on the structural vibration, especially if the spatial ordinal number is near the number of teeth. Furthermore, it is shown that the structure may react sensitively to axial variations of the forces, particularly near distinct structural resonances.

Originality/value

The presented investigations show relevant issues influencing the noise behaviour of electrical machines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

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Article

Branko Tadic, Bojan Bogdanovic, Branislav M. Jeremic, Petar M. Todorovic, Ognjan Luzanin, Igor Budak and Djordje Vukelic

– The purpose of this paper is to propose a general model for locating and clamping workpieces of complex geometry with two skewed holes under multiple constraints.

Abstract

Purpose

The purpose of this paper is to propose a general model for locating and clamping workpieces of complex geometry with two skewed holes under multiple constraints.

Design/methodology/approach

Numerous constraints related to application of the proposed model are discussed as prerequisite to design of fixture solution. Based on theoretical model, a fixture was designed and successfully tested in experimental investigation. Experimental results were also verified using FEM simulations.

Findings

This study showed that, opposed to conventional approach, novel solution results in significantly smaller fixture dimensions, while providing greater stability. Insertion of mandrels and supports element sub-assemblies into the workpiece holes significantly increases workpiece stiffness through an increased moment of inertia, while the internal support elements largely diminish the problem of thin wall deformation in the workpiece.

Practical implications

The fixture designed in this case was actually used in industrial application to accommodate a thin-walled casting of gearbox housing, where it proved to be a very stable framework. It can be used in industry without any major readjustments.

Originality/value

According to available literature, this work is the first successful implementation of a fixture solution in which the problem of multiple constraints is solved by attaching centering elements, support sub-assemblies, and other fixture elements to the internal workpiece walls, and then locating them in the second part of the fixture.

Details

Assembly Automation, vol. 33 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

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Article

Piotr Tyczyński, Jan Lemańczyk, Robert Ostrowski and Romana Ewa S´liwa

The purpose of this paper is to analyze machinability of CFRP, GFRP, GLARE-type composites in drilling process taking into account their features and properties (the…

Abstract

Purpose

The purpose of this paper is to analyze machinability of CFRP, GFRP, GLARE-type composites in drilling process taking into account their features and properties (the geometric characteristics, the volume fraction and the mechanical properties of the individual components of the composite). Drilling in non-plan surfaces and slope drilling.

Design/methodology/approach

The tests were carried out in two stages: perpendicular drilling of materials such as GLARE with special drill bits, and drilling of composite structures with non-planar surfaces made of unidirectional carbon fiber prepregs, using the modified special drill. Measurement of cutting forces and torque, stress distribution (photoelastic method) and a visual assessment of defects occurring during drilling allowed to determine the relationship between the type and geometry of the composite drill.

Findings

Identified great effect of kind of composite on the machinability of these materials has substantiated modification of the standard geometry of drills and matching this geometry to specific properties of the various type of composites.

Practical implications

Drilling of assembly holes for aerospace parts.

Originality/value

New type of drill geometry for different type of composite.

Details

Aircraft Engineering and Aerospace Technology: An International Journal, vol. 86 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

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