In turning thin-walled parts, machining errors and deviations from the aspired workpiece shape occur due to influences of the workpiece clamping and elastic deformations of the workpiece caused by ...clamping forces. This paper introduces a newly designed sensor integrated chuck jaw for turning applications, which allows for an on-line monitoring of the actual clamping forces and an in-process prediction of shape deviations of the machined parts. The design and characteristics of the sensory jaw are described and its monitoring capability is validated in turning experiments. Correlations of sensor data with workpiece shape deviations and models for error prediction are analyzed.
Evaluating surface frequency components in the fabrication process is critical for controlling the machined surface quality. The presence of anisotropic ripples on diamond-turned surfaces makes this ...challenging. A multiscale frequency evaluation method, referred to as Surface Intrinsic Mode Decomposition (SIMD), is proposed for evaluating on-machine surface measurement (OMSM) data. It decomposes continuous surface probing profiles, incorporating both temporal and spatial frequency information. In comparison to the conventional power spectral density (PSD) analysis method, the approach enriches frequency details over a wider range, which contributes to a more comprehensive understanding of surface quality and helps to identify mid-spatial frequency (MSF) errors.
Various non-coated micro-grooves with 7–149μm in depth and 0.14–0.50 in aspect ratio are proposed on tool rake surfaces along cutting chip flowing. The objective is to understand how the micro-groove ...shape and size influence cutting temperature and cutting force in dry turning of titanium alloy. First, the micro-grinding with a diamond wheel V-tip was employed to fabricate accurate and smooth micro-grooves; then dry turning experiments were performed with regard to material removal rate; finally, cutting temperature, cutting force and tool wear were investigated. It is shown that these micro-grooves patterned on tool rake surface contribute to decreasing cutting chip frictions and excluding cutting heat. The micro-grooved tool decreases cutting temperature by 103°C and more against traditional plane tool. The predicted cutting tip temperature reaches about 1322°C for traditional plane tool, but it does only about 500°C for micro-grooved tool. Moreover, the cutting temperature decreases and the shear angle increases with decreasing micro-groove depth except for the case of 7μm in micro-groove depth. The 25-μm-depth micro-grooved tool decreases cutting temperature and cutting force more greatly in larger material removal rate turning. In the dry turning with a micro-grooved tool, it is required that the micro-groove width is less than cutting chip width and its aspect ratio is enough large to maintain the air spaces between chip back surface and tool rake surface.
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•The micro-grinding may be used to fabricate accuracy and smooth micro-grooves on tool rake surface.•The micro-grooved tool may decrease cutting temperature by 103° and more against plate tool.•The 25-μm-depth micro-grooved tool decrease cutting temperature and force more greatly in larger material removal rate turning.•The micro-groove depth and width influence cutting temperature and force.
Abstract
There are situations when obtaining surfaces that correspond to one-sheeted revolution hyperboloid surface is formulated in industrial practice. Solving such a problem may require the use of ...expensive procedures and equipment. The analysis of some solutions from the specialized literature led to the acceptance of some possibilities to obtain certain surfaces specific to the one- sheeted revolution hyperboloids by turning and milling. A technological solution that involves using a milling device adaptable to a universal lathe has been proposed.
This article reports on the mechanism design, dimension optimization, closed-loop control, and practical application of a piezoelectrically actuated fast tool servo (FTS) for the diamond turning of ...microstructured surfaces. With the mechanism, a finite-element based analytical model is developed to theoretically relate the working performance with its structural dimensions. Considering its application for micro/nanocutting, the structural dimensions of the mechanism are deliberately determined through evolutionarily optimizing a comprehensive objective. To ultrafinely track the cutting trajectory with a high bandwidth, a proportional-integral-derivative controller together with the dynamics inversion based feedforward compensation is optimally designed with assistance of the Nyquist diagram, and a disturbance observer is further employed to compensate for the inherent hysteresis nonlinearity as well as external cutting force disturbances. Both open-loop and closed-loop experimental tests on the prototype suggest that a stroke of 18 <inline-formula><tex-math notation="LaTeX"> \mu</tex-math></inline-formula>m and a closed-loop bandwidth of 1730 Hz are achieved. Taking advantage of the newly developed FTS, two typical microstructured surfaces are ultraprecisely turned, well demonstrating the effectiveness of the FTS.
Ultrasonic vibration assisted turning (UAT) is a machining method for creating precision surfaces that because of advantages such as increased tool life, decreased cutting force, high surface ...quality, and increasing the machinability of hard cutting materials is widely used. In this method, optimal choice of machining parameters has a significant effect on the obtained surface texture. This paper examines the parameters that influence surface texture in the UAT. Therefore, an algorithm was provided to simulate surface textures in the process of ultrasonic vibration assisted face-turning in three modes of one-dimensional, two-dimensional and three-dimensional. To validate this algorithm, experimental tests were performed on Al7075-T6. Comparing the results of the algorithm and experimental tests shows that the surface texture resulted from simulation algorithm is well-matched with the results of experimental tests. Finally, the effect of machining parameters of cutting speed and feed rate are investigated in a variety of vibration modes applied to the tool.
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•Ultrasonic vibration assisted turning(UAT)•Precision surfaces of Machining•High surface quality•Hard cutting materials•Surface texture Simulation
State of the art in hard turning Bartarya, Gaurav; Choudhury, S.K.
International journal of machine tools & manufacture,
02/2012, Letnik:
53, Številka:
1
Journal Article
Recenzirano
Hard turning is gaining grounds for machining hardened steels as it has several benefits over grinding. There are several issues, which should be understood and dealt with, to achieve successful ...performance of the process. Researchers have worked upon several aspects related to hard turning. The present work is an effort to review some of these works and to understand the key issues related to process performance. The review shows that the type of tool material, cutting edge geometry and cutting parameters affect the process efficiencies in terms of tool forces, surface integrities integrity, and white layer. Adequate machine rigidity is a must essential to minimize the process inaccuracies. Also moreover, for finish hard turning, where the depth of cut is less than the nose radius of the tool, the forces deviate from the conventional trends as the radial force component is the maximum and axial force component becomes minimum. The present work finally lists down certain areas that can be taken up for further research in hard turning.
► Review shows many areas and problems still to be addressed in hard turning. ► Effective investigations about force and friction conditions are still to be taken up. ► Very little work has been done to reduce tensile stresses on the machined surface. ► Different phases in hardened steel are cut simultaneously by the tool. ► So, forces should be modelled on microstructure level.
The present work focuses on the performance of vegetable oil based nanofluids on machining performance during turning of AISI 1040 steel through minimum quantity lubrication (MQL). Different samples ...of nanofluids are formulated using dispersions of nanomolybdenum disulphide (nMoS2) in coconut (CC), sesame (SS) and canola (CAN) oils at varying nanoparticle inclusions (npi) and examined for basic properties. Machining parameters are measured during machining. It is observed that basic properties have increased with increase in npi, except absorbance. 0.5%CC+nMoS2is found to exhibit better machining performance compared to all the lubricant conditions. Cutting forces, temperatures, tool wear and surface roughness are approximately reduced by 37%, 21%, 44% and 39% respectively by using CC+nMoS2 at 0.5% npi compared to dry machining.
•Thermo-physical properties of vegetable oil based nanofluids are evaluated.•Machining performance of nanofluids is assessed at varying npi.•0.5% nMoS2+CC improved machining performance compared to other nanofluids.
The attenuation and fluctuation of ultrasonic vibration amplitude caused by the change of cutting load have become crucial factors limiting the precision improvement of the 2D ultrasonic-assisted ...turning (2DUAT). Therefore, the precise control of ultrasonic amplitude is very critical for 2DUAT precision improvement. However, it is difficult to arrange external sensors since the contact between the tool and the workpiece. Here, a novel 2D sensing and actuating integrated ultrasonic turning tool (2DSAIUTT) is proposed. The sensing and actuating of 2D amplitude are realized simultaneously with a single longitudinal-bending hybrid transducer without external sensors. First, the structure of 2DSAIUTT is designed and its open-loop characteristics are tested. Then, a negative feedback decoupler is proposed to overcome the coupling between the longitudinal and bending self-sensing signals, by which the self-sensing error is reduced by 70.1%. Finally, a cutting experiment under variable depth-of-cuts (DOCs) is carried out. The results show that the amplitude control error under variable DOC load is less than ±0.156 μ m. Moreover, the precision is 70.8% higher than that of traditional 2DUAT, and the surface roughness of stainless-steel turning reaches Sa0.127 μ m. These advantages show that 2DSAIUTT has great potential in the field of ultra-precision machining.
•Owing to the unique nature of UVAT processes in creating micro-dimples on the surface, surface geometric properties and 3D parameters of roughness improve and surface hardness increases. These ...factors cause increased wear resistance and decreased friction coefficient.•The results obtained from topography of surface texture and micro-hardness shows that the increased feed rate leads to the improvement of 3D parameters of roughness and surface hardness. As a result, wear resistance and friction coefficient decrease.•ANOVA results for average friction coefficient indicate that type of UVAT process with 32.32% effectiveness has the most effect on average friction coefficient. Feed rate and cutting speed with the effectiveness of 17.46% and 11.73% are other parameters which affect output parameter of average friction coefficient.
Ultrasonic vibration-assisted turning process (UVAT) is one of the effective methods in improving the tribological properties. In this research, the effect of different machining parameters such as cutting speed and feed rate as well as the effect of three vibration modes of one-dimensional (LVT), elliptical (EVT), and three-dimensional (3D-VT) on the tribological properties is examined. In order to validate the results of UVAT process, conventional face-turning operation was performed as well. Wear and friction tests were performed using pin-on-disk wear and friction machine with identical vertical load and sliding speed. The results of the tests show that the surfaces upon which micro-dimples have been created by UVAT processes reduce the average friction coefficient, wear rate and adhesion between pin and samples surface compared with conventional machined surfaces. Compared with conventional face-turning surfaces, average friction coefficient of the surfaces face-turned by LVT, EVT, and 3D-VT processes, show a maximum decrease of 13%, 18%, and 21% respectively. Moreover, compared with CT process, because of the unique features of UVAT process in creating micro-dimples, the contact between chrome steel pin and the sample surface decreases; this in turn leads to further reduction in wear rate for the processes of LVT, EVT, and 3D-VT respectively.
