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Number of results: 55
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Abstract

The methods of making diamond tools have undergone a remarkable development since the invention of synthetic diamond in the mid-1950s. The current review summarises key historical, recent and ongoing trends and developments in sintered diamond tools. The report concentrates on tools used within the stone and construction industries which, being the main consumers of metal-bonded diamond tools fabricated by powder metallurgy (P/M) technology, have always fuelled advances in tool design and production technologies.
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Authors and Affiliations

J. Konstanty
1
ORCID: ORCID

  1. AGH – University of Science & Technology, Al. Mickiewicza 30, 30-059 Krakow, Poland
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Abstract

The paper presents the results of research on the modification of the face geometry of the refill friction stir spot welding tool sleeve for welding thin aluminum sheets with an Alclad and an oxide anode coating. The analysis of the impact of such modification on the process perform (tool motion parameters, temperature) and microstructure as well as mechanical strength of the lap joints were analyzed. The tests were carried out using aluminum alloy 2024-T3 sheets with thickness 1.27 mm. For comparative purposes, joints were also made using plates without an Alclad and without anodized coating with using unmodified tool and modified tools with developed 3 variants of face geometry. The samples with the joint were subjected to metallographic and strength tests. It has been shown that the use of modified geometry has a decisive influence on the performance of the process and the effect of softening and mixing of materials in the zone of point connection.

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Authors and Affiliations

W. Łogin
R.E. Śliwa
R. Ostrowski
J. Andres
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Abstract

Tests were performed on example tools applied in hot die forging processes. After withdrawal from service due to excessive wear, these tools can be regenerated for re-use through machining and hardfacing. First, analysis of worn tools was carried out for the purpose of identifying tool working conditions and wear mechanisms occurring in the surface layer of tools during forging. Testing of worn tools included observations under a microscope, surface scanning and microhardness measurement in the surface layer. The results indicate very diverse work conditions, which suggest the application of different materials and hardfacing tool regeneration technology in individual die forging processes.
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Authors and Affiliations

P. Widomski
1
ORCID: ORCID
M. Kaszuba
1
ORCID: ORCID
J. Krawczyk
1
ORCID: ORCID
B. Nowak
2
ORCID: ORCID
A. Lange
1
ORCID: ORCID
P. Sokołowski
1
ORCID: ORCID
Z. Gronostajski
1
ORCID: ORCID

  1. Wroclaw University of Science and Technology, Department of Metal Forming, Welding and Metrology, 7-9 Lukasiewicza Str., 50-371, Wroclaw, Poland
  2. CEO, Kuźnia Jawor S.A. Poland
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Abstract

The paper deals with evaluation of a 3D scanning method elaborated by the authors, by applying it to the analysis of the wear of forging tools. The 3D scanning method in the first place consists in the application of scanning to the analysis of changes in geometry of a forging tool by way of comparing the images of a worn tool with a CAD model or an image of a new tool. The method was evaluated in the context of the important measurement problems resulting from the extreme conditions present during the industrial hot forging processes. The method was used to evaluate wear of tools with an increasing wear degree, which made it possible to determine the wear characteristics in a function of the number of produced forgings. The following stage was the use it for a direct control of the quality and geometry changes of forging tools (without their disassembly) by way of a direct measurement of the geometry of periodically collected forgings (indirect method based on forgings). The final part of the study points to the advantages and disadvantages of the elaborated method as well as the potential directions of its further development.

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Authors and Affiliations

Marek Hawryluk
Jacek Ziemba
Łukasz Dworzak
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Abstract

In recent years the application of computer software to the learning process has been found to be an indisputably effective tool supporting the traditional teaching methods. Particular focus has been put on the application of techniques based on speech and language processing to the second language learning. Most of the commercial self-study programs, however, do not allow for introduction of an individualized learning course by the teacher and to concentrate on segmental features only. The paper discusses the use of speech technology in the training of foreign languages' pronunciation and prosody and defines pedagogical requirements for an effective training with CAPT systems. In this context, steps taken in the development of the intelligent tutoring system AzAR3.0 (German ‘Automat for accent reduction’) in the scope of the Euronounce project (Cylwik et al., 2008) are described with the focus on creation of the linguistic content. In response to the European Union's call for promoting less widely spoken languages, the project focuses on German as a target language for native speakers of Polish, Slovak, Czech, and Russian, and vice versa. The paper presents the design of the speech corpus for the purpose of the tutoring system and the analysis of pronunciation errors. The results of the latter provide information which is important for Automatic Speech Recognition (ASR) training on the one hand, and for automatic error detection and feedback generation on the other hand. In the end, Pitch Line software for implementation in the prosody visualization and training module of AzAR3.0 tutoring system is described.

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Authors and Affiliations

Grażyna Demenko
Agnieszka Wagner
Natalia Cylwik
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Abstract

Description of program tools simplifying simulation applications building for physical phenomenons described by differential equations in state equations form modeling is presented in the paper. A method for using prepared libraries for squirrel-cage motors including any motor damages modeling had been described. For that purpose, squirrel-cage motor mathematical model in natural coordinates system had been presented. Presented solutions provide also supply sources (inverters) modeling, including their microprocessor implementation and other phenomenons, that assume state equation structure step changes, depending on variable limitations and time value.
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Authors and Affiliations

Adam Sołbut
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Abstract

This article discusses results of an analysis of mechanical properties of a sintered material obtained from a mixture of elemental iron, copper and nickel powders ball milled for 60 hours. The powder consolidation was performed by hot pressing in a graphite mould. The hot pressing was carried out for 3 minutes at 900 °C and under a pressure of 35 MPa. The sintered specimens were tested for density, porosity, hardness and tensile strength. Their microstructures and fracture surfaces were also examined using a scanning electron microscope (SEM). The study was conducted in order to determine the suitability of the sintered material for the manufacture of metal-bonded diamond tools. It was important to assess the effects of chemical composition and microstructure of the sintered material on its mechanical properties, which were compared with those of conventional metal bond material produced from a hot-pressed SMS grade cobalt powder. Although the studied material shows slightly lower strength and ductility as compared with cobalt, its hardness and offset yield strength are sufficiently high to meet the criteria for less demanding applications.

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Authors and Affiliations

J. Lachowski
J.M. Borowiecka-Jamrozek
J. Konstanty
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Abstract

The paper presents the results of theoretical analysis and experimental research on the material’s influence and tool geometry on the welding speed and mechanical strength of Al 2024 thin sheet metal joints. To make the joints, tungsten carbide and ceramics tools with a smooth and modified surface of the shoulder were used. The choice of the geometrical parameters of the tool was adjusted to the thickness of the joined sheet. During welding, the values of axial and radial force were recorded to determine the stability of the process. The quality of the joint was examined and evaluated on the basis of visual analysis of the surface and cross-sections of the joint area and the parent material, and subjected to mechanical strength tests. The test results indicate that both the geometry of the tool shoulder and the tool material have a decisive influence on the quality of the joint and the welding speed, making it possible to shorten the duration of the entire process.

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Authors and Affiliations

S. Buszta
P. Myśliwiec
R.E. Śliwa
R. Ostrowski
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Abstract

Touch-trigger probes for CNC milling machines usually use wireless communication in the radio or IR band. Additionally they enable triggering signal filtering in order to avoid false triggers of the probe. These solutions cause a delay in trigger signal transmission from the probe to the machine tool controller. This delay creates an additional pre-travel component, which is directly proportional to the measurement speed and which is the cause of a previously observed but not explained increase of the pre-travel with the increase of the measurement speed. In the paper, a method of testing the delay time of triggering signal is described, an example of delay time testing results is presented and the previous, unexplained results of other researchers are analysed in terms of signal transmission delay.
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Authors and Affiliations

Michał Jankowski
Adam Woźniak
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Abstract

Computer-aided tools help in shortening and eradicating numerous repetitive tasks that reduces the gap between digital model and actual product. Use of these tools assists in realizing free-form objects such as custom fit products as described by a stringent interaction with the human body. Development of such a model presents a challenging situation for reverse engineering (RE) which is not analogous with the requirement for generating simple geometric models. Hence, an alternating way of producing more accurate three-dimensional models is proposed. For creating accurate 3D models, point clouds are processed through filtering, segmentation, mesh smoothing and surface generation. These processes help in converting the initial unorganized point data into a 3D digital model and simultaneously influence the quality of model. This study provides an optimum balance for the best accuracy obtainable with maximum allowable deviation to lessen computer handling and processing time. A realistic non trivial case study of free-form prosthetic socket is considered. The accuracy obtained for the developed model is acceptable for the use in medical applications and FEM analysis.

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Authors and Affiliations

Vimal Kumar Pathak
Chitresh Nayak
Amit Kumar Singh
Himanshu Chaudhary
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Abstract

The main purpose of the work was to determine the powder influence of the powder preparation on the microstructure and properties of iron-based sinters used as a metallic-diamond matrix. The sinters obtained from a mixture of comercial powders were used for research. A mixture of powders was selected for the tests, in which the mass fractions of individual powders were as follows: 60% Fe, 23.8% Cu, 4.2% Sn and 12% Ni. The powders were pre-mixed in a Turbula mixer and next a part of material was subjected to milling in a ball mill. Sintering was performed using hot-pressing technique in a graphite mould. The investigated properties of the sinters were concerned density, porosity, hardness, oxygen content, static tensile test and analysis of microstructure. Spot chemical analysis revealed the presence of Fe solution, Cu solution and the presence of iron oxides oxides. Nickel atoms were present throughout the sinter volume. The obtained test results showed that the presented sinter has good functional properties (hardness and thermal expansion) and can be used as a diamond-metal composite matrix in diamond tools.The microstructure and mechanical properties of sinters were investigated.
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Authors and Affiliations

Jan Lachowski
1
ORCID: ORCID
Joanna Borowiecka-Jamrozek
1
ORCID: ORCID

  1. Kielce University of Technology, 7 Tysiąclecia P.P. Av., 25-314 Kielce, Poland
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Abstract

A laser measurement system for measuring straightness and parallelism error using a semiconductor laser was proposed. The designing principle of the developed system was analyzed. Addressing at the question of the divergence angle of the semiconductor laser being quite large and the reduction of measurement accuracy caused by the diffraction effect of the light spot at the longworking distance, the optical structure of the system was optimized through a series of simulations and experiments. A plano-convex lens was used to collimate the laser beam and concentrate the energy distribution of the diffraction effect. The working distance of the system was increased from 2.6 m to 4.6 m after the optical optimization, and the repeatability of the displacement measurement is kept within 2.2 m in the total measurement range. The performance of the developed system was verified by measuring the straightness of a machine tool through the comparison tests with two commercial multi-degree-of-freedom measurement systems. Two different measurement methods were used to verify the measurement accuracy. The comparison results show that during the straightness measurement of the machine tool, the laser head should be fixed in front of the moving axis, and the sensing part should move with the moving table of the machine tool. Results also show that the measurement error of the straightness measurement is less than 3 m compared with the commercial systems. The developed laser measurement system has the advantages of high precision, long working distance, low cost, and suitability for straightness and parallelism error measurement.
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Bibliography

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[2] Chen, Z., & Liu, X. (2020). A Self-adaptive interpolation method for sinusoidal sensors. IEEE Transactions on Instrumentation and Measurement, 69(10), 7675–7682. https://doi.org/10.1109/ TIM.2020.2983094
[3] Acosta, D., & Albajez, J. A. (2018). Verification of machine tools using multilateration and a geometrical approach. Nanomanufacturing and Metrology, 1(1), 39–44. https://doi.org/10.1007/ s41871-018-0006-y
[4] Chen, B. Y., Zhang, E. Z., & Yan, L. P. (2009). A laser interferometer for measuring straightness and its position based on heterodyne interferometry. Review of Scientific Instruments, 80(11), 115113. https://doi.org/10.1063/1.3266966
[5] Zhu, L. J., Li, L., Liu, & J. H. (2009). A method for measuring the guideway straightness error based on polarized interference principle. International Journal of Machine Tools and Manufacture, 49(3–4), 285–290. https://doi.org/10.1016/j.ijmachtools.2008.10.009
[6] Lin, S. T. (2001). A laser interferometer for measuring straightness. Optics & Laser Technology, 33(3), 195–199. https://doi.org/10.1016/S0030-3992(01)00024-X
[7] Jywe, W. Y., Liu, C. H., Shien, W. H., Shyu, L. H., & Fang, T. H. (2006). Development of a multidegree of freedoms measuring system and an error compensation technique for machine tools. Journal of Physics Conference Series, 48(1), 761–765. https://doi.org/10.1088/1742-6596/48/1/144
[8] Feng, Q. B., Zhang, B. & Cui, C. X. (2013). Development of a simple system for simultaneous measuring 6DOF geometric motion errors of a linear guide. Optics Express, 21(22), 25805–25819. https://doi.org/10.1364/OE.21.025805
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[10] Fan, K. C. (2000). A laser straightness measurement system using optical fiber and modulation techniques. International Journal of Machine Tools Manufacture, 40(14), 2073–2081. https://doi.org/ 10.1016/S0890-6955(00)00040-7
[11] Hsieh, T. H., Chen, P. Y., & Jywe, W. Y. (2019). A geometric error measurement system for linear guideway assembly and calibration. Applied Sciences, 9(3), 574. https://doi.org/10.3390/app9030574
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[13] Rahneberg, I., & Büchner, H. J. (2009). Optical system for the simultaneous measurement of twodimensional straightness errors and the roll angle. Proceedings of the International Society for Optics and Photonics, the Czech Republic, 7356. https://doi.org/10.1117/12.820634
[14] Chou, C., Chou, L. Y. & Peng, C. K. (1997). CCD-based CMM geometrical error measurement using Fourier phase shift algorithm. International Journal of Machine Tools and Manufacture, 37(5): 579–590. https://doi.org/10.1016/S0890-6955(96)00078-8
[15] Sun, C., Cai, S., & Liu, Y. (2020). Compact laser collimation system for simultaneous measurement of five-degree-of-freedom motion errors. Applied Sciences, 10(15), 5057. https://doi.org/10.3390/app10155057
[16] Huang, Y., Fan, Y., Lou, Z., Fan, K. C., & Sun, W. (2020). An innovative dual-axis precision level based on light transmission and refraction for angle measurement. Applied Sciences, 10(17), 6019. https://doi.org/10.3390/app10176019
[17] Born M., & Wolf E. (2013). Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light. Elsevier. https://www.sciencedirect.com/book/9780080264820/ principles-of-optic
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Authors and Affiliations

Peng Xu
1
Rui Jun Li
1
Wen Kai Zhao
1
Zhen Xin Chang
1
Shao Hua Ma
1
Kuang Chao Fan
1

  1. Hefei University of Technology, School of Instrument Science and Opto-Electronics Engineering, Hefei, China
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Abstract

The paper presents the results of research and analysis of the effect of joining by the RFSSW method of alclad sheets made of Al2024 with an anodic oxide coating, with the using the tool with modified geometry of the front surface of inner sleeve. The different effects of the modifications made on the phenomenon of plasticization and stirring of materials in the process of creating a weld, microstructure of welds and mechanical strength of lap joints were shown. The tests were carried out on 1.27 mm thick sheets, with the use of an unmodified tool and modified tools with three variants of the geometry. The welds and the joints samples were subjected to metallographic and strength tests. It has been shown that the use of a properly selected modified geometry has a beneficial effect on the transport of materials to be joined in the joint zone (flow pattern of plasticized layers and the stirring effect) during the welding, which translates into the strength of the joints and the nature of the weld failure.
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Authors and Affiliations

W. Łogin
1
ORCID: ORCID
R.E. Śliwa
2
ORCID: ORCID
R. Ostrowski
2
ORCID: ORCID

  1. Development Project Office, Polskie Zakłady Lotnicze w Mielcu Sp. z o.o., Poland
  2. Rzeszów University of Technology, 12 Powstańców Warszawy Av., 35-959 Rzeszów, Poland
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Abstract

The main objective of the present work was to determine the effect of powder composition on microstructure and properties of iron-base materials used as matrices in diamond impregnated tools. The Fe-Cu-Ni powders premixed and ball-milled for 30 hours, were used for the experiments. The influence of manufacturing process parameters on microstructure and mechanical properties of produced sinters was investigated. Sintering was done by hot-pressing technique in graphite mould. The powders were consolidated to a virtually pore-free condition during 3 minutes hold at 35MPa and 900°C. Investigations of the sintered materials included: density, hardness, static tensile test and X-ray diffraction (XRD) analysis. Microstructural and fractographic observations were also made with a scanning electron microscope (SEM). The obtained results indicate that the sintered parts have a high density, close to the theoretical value, good plasticity, relatively high hardness and yield strength, and are characterized by a coarse-grained microstructure.

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Authors and Affiliations

J. Borowiecka-Jamrozek
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Abstract

Electromagnetic theoretical concepts, which are represented mathematically, are usually challenging to grasp by students. In this study, we explore an interactive technology-based teaching tool to develop further students’ mastery of electromagnetic concepts through learning development and visualization of electromagnetic problems. This visualization of the problems will help students analyse, evaluate, and draw conclusions of the impact of electromagnetic-related problems in real-life. The simulation tool in this study is based on a MATLAB® toolbox package, in which partial-differential equations (PDE) solver is the core engine. In this paper, we will also provide a step-by-step guide on the use of such an interactive computer-aided tool so that it can be a great self-guide tool for beginners in the field of physics and a first-level introductory course in electromagnetism. This study will focus mainly on one classical electrostatic problem that is a challenge to students to visualize, analyze and evaluate. Based on students feedback by the end of the course, 80% of students’ population are more comfortable with the introduced interactive learning tool.
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Authors and Affiliations

Mohammed M. Bait-Suwailam
1 2
Joseph Jervase
1
Hassan Al-Lawati
1
Zia Nadir
1

  1. Department of Electrical and Computer Engineering, Sultan Qaboos University, Muscat, Oman
  2. Remote Sensing and GIS Research Center, Sultan Qaboos University
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Abstract

The paper concerns a risk assessment and management methodology in critical infrastructures. The aim of the paper is to present researches on risk management within the experimentation tool based on the OSCAD software. The researches are focused on interdependent infrastructures where the specific phenomena, like escalating and cascading effects, may occur. The objective of the researches is to acquire knowledge about risk issues within interdependent infrastructures, to assess the usefulness of the OSCAD-based risk manager in this application domain, and to identify directions for further R&D works. The paper contains a short introduction to risk management in critical infrastructures, presents the state of the art, and the context, plan and scenarios of the performed validation experiments. Next, step by step, the validation is performed. It encompasses two collaborating infrastructures (railway, energy). It is shown how a hazardous event impacts the given infrastructure (primary and secondary eects) and the neighbouring infrastructure. In the conclusions the experiments are summarized, the OSCAD software assessed and directions of the future works identified.

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Authors and Affiliations

Andrzej Białas
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Abstract

Passion fruit is an important fruit crop grown in parts of southern and north-eastern states of India. Leaf curl symptoms typical to begomovirus infection were observed on passion fruit plants at three locations of Madikeri District, Karnataka State, India. The disease incidence ranged from 10–20% in all the locations. In order to determine if the begomovirus was associated with leaf curl disease of passion fruit, 20 infected samples collected from different locations were subjected to PCR analysis using primers specific to begomovirus. This resulted in an expected PCR product of ~1.2 kb. Sequence analysis of these products revealed that they have more than 98% similarity among them and have similarity with other begomoviruses. Complete genome sequencing of begomovirus associated with one sample (PF1 collected from CHES, Madikeri) was done using RCA. Further, sequencing of betasatellite and alphasatellite was done after PCR amplification using specific primers. Complete DNA-A sequence of PF-isolate with other begomoviruses revealed that it shared nucleotide (nt) identity of 87.8 to 88.8% with Ageratum enation virus. This indicated the association of a novel begomovirus with leaf curl disease of passion fruit in India, for which we propose the name, Passion fruit leaf curl virus (PFLCuV) [IN-Kar-18]. PFLCuV associated betasatellite shared 98.3% sequence identity with Tomato leaf curl Bangladesh betasatellite, while alphasatellite had 95.7% sequence identity with Cotton leaf curl Multan alphasatellite. Recombinant analysis indicated a major component of PFLCuV DNA-A may have originated from a recombination of earlier reported begomoviruses. Recombination as well as GC plot analysis showed that the recombination occurred in the genome regions having low GC content regions of PFLCuV. However, there is no evidence of recombination in alphasatellite and betasatellite associated with leaf curl disease of passion fruit. This is the first record of a novel begomovirus and satellites associated with leaf curl disease of passion fruit from India.
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Authors and Affiliations

Venkataravanappa Venkataravanappa
1
Lakshminarayana Reddy Cheegatagere Narasimha Reddy
2
Shridhar Hiremath
2
Bommanahalli Munivenkategowda Muralidhara
3
Suryanarayana Vishweswarasastry
4
Virendra K. Baranwal
5
Krishna Reddy Manem
6

  1. Central Horticultural Experimental Station, Indian Council of Agricultural Research – Indian Institute of Horticultural Research, Chettalli, Madikeri, Karnataka, India
  2. Department of Plant Pathology, University of Agricultural Sciences, Gandhi Krishi Vigyana Kendra, Bangalore, Karnataka, India
  3. Indian Council of Agricultural Research – Directorate of Cashew Research, Puttur, Karnataka, India
  4. Department of Forest Biology and Tree Improvement, University of Agricultural Science, Dharwad, Sirsi, Karnataka, India
  5. Division of Plant Pathology, Indian Council of Agricultural Research – Indian Agricultural Research Institute, New Delhi, India
  6. Indian Council of Agricultural Research – Indian Institute of Horticultural Research, Hessaraghatta Lake, Bangalore, Karnataka, India
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Abstract

Friction stir welding (FSW) currently contributes a significant joining process for welding aluminium, magnesium, and other metals in which no molten or liquid state were involved. It is well known that aluminium alloys are more effective, promising for different applications light weight, strength and low cost. This study aims to determine how such tools geometry and tool speed can be related to dissimilar material in the joining process. Specifically, it investigates whether the distribution of the weld zone particularly between tool pin profile to rotational speed. In this context, the influence of tool pin profile and tool rotational speed in relation to the mechanical properties and microstructure of friction stir welded. The aim of this study is also to test the hypothesis that better mixing between dissimilar metals at higher tool rotational speed along the weld path. Three different tool profiles were configured with AA5083 and AA7075. During welding, notable presence of various types of defects such as voids and wormholes in the weld region. The results of this work showed that the tool pin profile and weld parameter are significant in determining mechanical properties at different tool rotational speed. The highest tensile strength achieved was about 263 MPa and the defectfree joint was obtained by using the threaded tapered cylindrical pin tool at a rotational speed of 800 rpm. These findings indicate that different tool profiles influence differently on the formation of defects at welds. On this basis, the tool geometry should be considered when designing experimental friction stir welded joint.
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Authors and Affiliations

M.H. Azmi
1
ORCID: ORCID
M.Z. Hasnol
1
ORCID: ORCID
M.F.A. Zaharuddin
1
ORCID: ORCID
S. Sharif
1
ORCID: ORCID
S. Rhee
2
ORCID: ORCID

  1. Universiti Teknologi Malaysia, School of Mechanical Engineering, Faculty of Engineering, 81310 Johor Bahru Johor, Malaysia
  2. Hanyang University, Department of Mechanical Engineering, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Korea
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Abstract

This paper presents the results of research into the cross wedge rolling (CWR) process of axle forgings. The presented results concern the parallel rolling process with two wedges. The use of two parallel wedges is aimed at shortening the tool length (increasing productivity) and reducing the values of wedge opening angles and increasing the forming angles, so that the condition 0.04 ≤ tgαtgβ ≤ 0.08 is maintained to guarantee the highest quality forgings. The article analyses the influence of the design of the double wedge tool on the geometric correctness of the forgings obtained, the value of the failure criterion and the force parameters of the process. The results obtained show that the use of multi wedge tools improves rolling conditions by increasing productivity and reducing the tendency of the material to crack with appropriately selected tool parameters.
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Authors and Affiliations

T. Bulzak
1
ORCID: ORCID

  1. Lublin University of Technology, Faculty of Mechanical Engineering, Department of Metal Forming, 36 Nadbystrzycka Str., 20-618, Lublin, Poland
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Abstract

The study discusses the issues of low durability of dies used in the first operation of producing a valve type forging from high nickel steel assigned for the application in motor truck engines. The analyzed process of manufacturing the exhaust valve forgings is realized in the coextrusion technology, followed by forging in closed dies. This process is difficult to master, mainly due to elevated adhesion of the charge material (high nickel steel – NCF3015) to the tool substrate as well as very high abrasive wear of the tool, most probably caused by the dissolution of hard carbide precipitates during the charge heating. A big temperature scatter of the charge during the heating and its short presence in the inductor prevents microstructure homogenization of the bearing roller and dissolution of hard precipitates. In effect, this causes an increase of the forging force and the pressures in the contact, which, in extreme cases, is the cause of the blocking of the forging already at the beginning of the process. In order to analyze this issue, complex investigations were conducted, which included: numerical modelling, dilatometric tests and hardness measurements. The microstructure examinations after the heating process pointed to lack of structure repeatability; the dilatometric tests determined the phase transformations, and the FEM results enabled an analysis of the process for different charge hardness values. On the basis of the conducted analyzes, it was found that the batch material heating process was not repeatable, because the collected samples showed a different amount of dissolved carbides in the microstructure, which translated into different hardnesses (from over 300 HV to 192 HV). Also, the results of numerical modeling showed that lower charge temperature translates into greater forces (by about 100 kN) and normal stresses (1000 MPa for the nominal process and 1500 MPa for a harder charge) and equivalent stresses in the tools (respectively: 1300 MPa and over 1800 MPa), as well as abrasive wear (3000 MPa mm; 4500 MPa mm). The obtained results determined the directions of further studies aiming at improvement of the production process and thus increase of tool durability.
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Authors and Affiliations

M.R. Hawryluk
1
ORCID: ORCID
M. Lachowicz
1
ORCID: ORCID
M. Janik
1
ORCID: ORCID
Z. Gronostajski
1
ORCID: ORCID
M. Stachowicz
1
ORCID: ORCID

  1. Wrocław University of Science and Technology, Faculty of Mechanical Engineering, 5 Ignacego Łukasiewicza Str., 50-371 Wrocław , Poland
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Abstract

The present research employs the statistical tool of Response surface methodology (RSM) to evaluate the machining characteristics of carbon nanotubes (CNTs) coated high-speed steel (HSS) tools. The methodology used for depositing carbon nanotubes was Plasma-Enhanced Chemical Vapor Deposition (PECVD). Cutting speed, thickness of cut, and feed rate were chosen as machining factors, and cutting forces, cutting tooltip temperature, tool wear, and surface roughness were included as machining responses. Three-level of cutting conditions were followed. The face-centered, Central Composite Design (CCD) was followed to conduct twenty number of experiments. The speed of cutting and rate of feed have been identified as the most influential variables over the responses considered, followed by the thickness of cut. The model reveals the optimized level of cutting parameters to achieve the required objectives. The confirmation experiments were also carried out to validate the acceptable degree of variations between the experimental results and the predicted one.
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Authors and Affiliations

Chandru Manivannan
1
ORCID: ORCID
Selladurai Velappan
2
ORCID: ORCID
Venkatesh Chenrayan
3
ORCID: ORCID

  1. Dhirajlal Gandhi College of Technology, Salem – 636309, Tamilnadu, India
  2. Coimbatore Institute of Technology, Coimbatore – 641014, Tamilnadu, India
  3. Adama Science and Technology University, Adama, Ethiopia
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Abstract

The sequential multilateration principle is often adopted in geometric error measurement of CNC machine tools. To identify the geometric errors, a single laser tracker is placed at different positions to measure the length between the target point and the laser tracker. However, the measurement of each laser tracker position is not simultaneous and measurement accuracy is mainly subject to positioning repeatability of the machine tool. This paper attempts to evaluate the measurement uncertainty of geometric errors caused by the positioning repeatability of the machine tool and the laser tracker spatial length measurement error based on the Monte Carlo method. Firstly, a direct identification method for geometric errors of CNC machine tools based on geometric error evaluation constraints is introduced, combined with the geometric error model of a three-axis machine tool. Moreover, uncertainty contributors caused by the repeatability of positioning of numerically controlled axes of the machine tool and the laser length measurement error are analyzed. The measurement uncertainty of the geometric error and the volumetric positioning error is evaluated with the Monte Carlo method. Finally, geometric error measurement and verification experiments are conducted. The results show that the maximum volumetric positioning error of the machine tool is 84.1 μm and the expanded uncertainty is 5.8 μm (�� = 2). The correctness of the geometric error measurement and uncertainty evaluation method proposed in this paper is verified compared with the direct geometric error measurement methods.
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Authors and Affiliations

Xingbao Liu
1
Yangqiu Xia
1
Xiaoting Rui
1

  1. Institute of Launch Dynamics, Nanjing University of Science and Technology, Nanjing 210094, China
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Abstract

The binary classifiers are appropriate for classification problems with two class labels. For multi-class problems, decomposition techniques, like one-vs-one strategy, are used because they allow the use of binary classifiers. The ensemble selection, on the other hand, is one of the most studied topics in multiple classifier systems because a selected subset of base classifiers may perform better than the whole set of base classifiers. Thus, we propose a novel concept of the dynamic ensemble selection based on values of the score function used in the one-vs-one decomposition scheme. The proposed algorithm has been verified on a real dataset regarding the classification of cutting tools. The proposed approach is compared with the static ensemble selection method based on the integration of base classifiers in geometric space, which also uses the one-vs-one decomposition scheme. In addition, other base classification algorithms are used to compare results in the conducted experiments. The obtained results demonstrate the effectiveness of our approach.

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Authors and Affiliations

Izabela Rojek
1
ORCID: ORCID
Robert Burduk
2
ORCID: ORCID
Paulina Heda
2

  1. Institute of Computer Science, Kazimierz Wielki University, ul. Chodkiewicza 30, 85-064 Bydgoszcz, Poland
  2. Faculty of Electronic, Wroclaw University of Science and Technology, ul. Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland

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