Pub Date : 2017-11-30DOI: 10.5545/SV-JME.2017.4529
J. Mei, Jiawei Zang, Yabin Ding, Shenglong Xie, Xu Zhang
This paper deals with the rapid and automatic zero-offset calibration of a 2-DOF parallel robot using distance measurements. The calibration system is introduced with emphasis on the design of a new measuring mechanism. A simplified error model of the robot is proposed after the sensitivity analyses of source errors, based on which a zero-offset identification model is developed using the truncated singular value decomposition (TSVD) method, and then it is modified with the manufacturing and assembly errors of the measuring mechanism (MAEMM). Furthermore, an optimization approach for selecting measurement positions is proposed by considering the condition number of the identification matrix. Finally, simulations and experiments are carried out to verify the effectiveness of the zero-offset calibration method. The results show that the identification model has good identifiability and robustness, and the position accuracy after calibration can be significantly improved.
{"title":"Rapid and Automatic Zero-Offset Calibration of a 2-DOF Parallel Robot Based on a New Measuring Mechanism","authors":"J. Mei, Jiawei Zang, Yabin Ding, Shenglong Xie, Xu Zhang","doi":"10.5545/SV-JME.2017.4529","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4529","url":null,"abstract":"This paper deals with the rapid and automatic zero-offset calibration of a 2-DOF parallel robot using distance measurements. The calibration system is introduced with emphasis on the design of a new measuring mechanism. A simplified error model of the robot is proposed after the sensitivity analyses of source errors, based on which a zero-offset identification model is developed using the truncated singular value decomposition (TSVD) method, and then it is modified with the manufacturing and assembly errors of the measuring mechanism (MAEMM). Furthermore, an optimization approach for selecting measurement positions is proposed by considering the condition number of the identification matrix. Finally, simulations and experiments are carried out to verify the effectiveness of the zero-offset calibration method. The results show that the identification model has good identifiability and robustness, and the position accuracy after calibration can be significantly improved.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86339261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-30DOI: 10.5545/SV-JME.2017.4307
Ningning Wang, Xueyi Li, Kun Wang, Q. Zeng, X. Shen
The transmission of spur gear mechanism may generate uneven load distribution because of machining error, assembly error, elastic deformation, and other factors, resulting in serious damage to the bearing capacity and service life of gears. To improve the contact condition of gear pairs and enhance the meshing performance and bearing capacity, this study proposed a novel axial modification method based on a composite modification curve with indefinite parameters and an evaluation method to evaluate modification effects. In addition to the surface equation of modified tooth was derived according to the composite modification curve, and the finite element model was built for gear pair. After conducting simulation analysis for the meshing process, the location and the shape of contact area as well as the other results can be acquired. In addition, the modification parameters can be optimized by performing orthogonal experiments for modified gear pairs; thus, the ideal modification effect is obtained at a specific operating condition. Moreover, comparison analysis was performed, and the results show that the phenomenon of uneven load distribution is dramatically improved when the gear pair was modified with optimized parameters, and the bearing capacity of the gear pair was increased. Finally, using the optimized parameters to trial-produce gears and conducting running-in tests, the effectiveness and the practicability of the method proposed in this study were verified.
{"title":"A Novel Axial Modification and Simulation Analysis of Involute Spur Gear","authors":"Ningning Wang, Xueyi Li, Kun Wang, Q. Zeng, X. Shen","doi":"10.5545/SV-JME.2017.4307","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4307","url":null,"abstract":"The transmission of spur gear mechanism may generate uneven load distribution because of machining error, assembly error, elastic deformation, and other factors, resulting in serious damage to the bearing capacity and service life of gears. To improve the contact condition of gear pairs and enhance the meshing performance and bearing capacity, this study proposed a novel axial modification method based on a composite modification curve with indefinite parameters and an evaluation method to evaluate modification effects. In addition to the surface equation of modified tooth was derived according to the composite modification curve, and the finite element model was built for gear pair. After conducting simulation analysis for the meshing process, the location and the shape of contact area as well as the other results can be acquired. In addition, the modification parameters can be optimized by performing orthogonal experiments for modified gear pairs; thus, the ideal modification effect is obtained at a specific operating condition. Moreover, comparison analysis was performed, and the results show that the phenomenon of uneven load distribution is dramatically improved when the gear pair was modified with optimized parameters, and the bearing capacity of the gear pair was increased. Finally, using the optimized parameters to trial-produce gears and conducting running-in tests, the effectiveness and the practicability of the method proposed in this study were verified.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80246509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-11-30DOI: 10.5545/SV-JME.2016.4196
V. Ostaševičius, V. Jūrėnas, A. Vilkauskas, G. Balevicius, A. Senkus, E. Jotautienė
Usage of ultrasound is prevalent in a wide range of industrial applications; it is employed in aiding the removal of hard-to-machine materials. In such cases, special care needs to be taken in designing an ultrasonic horn, as the geometrical make-up of this part that strongly influences the ultrasonic power output, frequency, and amplitude transferred to the area of effect. This article proposes a novel solution to the excitation of rotating interfaces: the excitation of the workpiece in cylindrical grinding. The approach focuses on the excitation of stationary centres, holding the workpiece, rather than the workpiece itself. The modelling and development procedures for a high-power actuator as well as experimental verifications to the validity and effectiveness of the approach are provided.
{"title":"A Novel Excitation Approach to Ultrasonically-Assisted Cylindrical Grinding","authors":"V. Ostaševičius, V. Jūrėnas, A. Vilkauskas, G. Balevicius, A. Senkus, E. Jotautienė","doi":"10.5545/SV-JME.2016.4196","DOIUrl":"https://doi.org/10.5545/SV-JME.2016.4196","url":null,"abstract":"Usage of ultrasound is prevalent in a wide range of industrial applications; it is employed in aiding the removal of hard-to-machine materials. In such cases, special care needs to be taken in designing an ultrasonic horn, as the geometrical make-up of this part that strongly influences the ultrasonic power output, frequency, and amplitude transferred to the area of effect. This article proposes a novel solution to the excitation of rotating interfaces: the excitation of the workpiece in cylindrical grinding. The approach focuses on the excitation of stationary centres, holding the workpiece, rather than the workpiece itself. The modelling and development procedures for a high-power actuator as well as experimental verifications to the validity and effectiveness of the approach are provided.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84735368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-30DOI: 10.5545/SV-JME.2017.4491
J. Mei, Shenglong Xie, Hai-tao Liu, Jiawei Zang
The pneumatic artificial muscle (PAM) has attracted extensive attention from both industrial and academic fields due to its high power/weight ratio and significant compliance. However, the inherent hysteresis nonlinearities, including force-length and length-pressure hysteresis, have significant influence on the accuracy of trajectory tracking control. This paper presents a generalized Prandtl-Ishlinskii (GPI) model and its inversion for the asymmetric hysteresis characterization and compensation of the PAM. By using the Levenberg-Marquardt (L-M) method, the parameters in the proposed GPI model are identified, based on which the simulation result of the GPI model and the measured experimental data are compared to validate the identification. To compensate for the nonlinear length-pressure hysteresis, a feedforward/feedback combined control scheme is developed to realize highly accurate trajectory tracking control of the PAM. The experimental results show that the inverse GPI model has a good capability of compensating the asymmetric length-pressure hysteresis.
{"title":"Hysteresis Modeling and Compensation of Pneumatic Artificial Muscles using the Generalized Prandtl-Ishlinskii Model","authors":"J. Mei, Shenglong Xie, Hai-tao Liu, Jiawei Zang","doi":"10.5545/SV-JME.2017.4491","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4491","url":null,"abstract":"The pneumatic artificial muscle (PAM) has attracted extensive attention from both industrial and academic fields due to its high power/weight ratio and significant compliance. However, the inherent hysteresis nonlinearities, including force-length and length-pressure hysteresis, have significant influence on the accuracy of trajectory tracking control. This paper presents a generalized Prandtl-Ishlinskii (GPI) model and its inversion for the asymmetric hysteresis characterization and compensation of the PAM. By using the Levenberg-Marquardt (L-M) method, the parameters in the proposed GPI model are identified, based on which the simulation result of the GPI model and the measured experimental data are compared to validate the identification. To compensate for the nonlinear length-pressure hysteresis, a feedforward/feedback combined control scheme is developed to realize highly accurate trajectory tracking control of the PAM. The experimental results show that the inverse GPI model has a good capability of compensating the asymmetric length-pressure hysteresis.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86671075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-30DOI: 10.5545/SV-JME.2017.4406
J. Kuczmaszewski, I. Zagórski, Olga Gziut, S. Legutko, G. Królczyk
This paper presents new approaches to safety assessment in the milling of magnesium alloy. The objective of the study is to determine the effect of milling parameters and end mill geometry on machining safety, defined as the minimum probability of chip self-ignition. The assessment of safety and effectiveness in the milling of magnesium must include analysis of chip fractions formed during the milling process. The paper presents the state of the art of magnesium alloy machinability in terms of chip formation (chip fragmentation). Furthermore, the paper investigates the correlation between the quantity of distinguished chip fractions and variations in the parameters vc and fz as well as in the rake angle γo. In addition, the results of the dimensions of individual chip fractions are reported. The study was conducted on AZ91HP magnesium cast alloy, and the milling process was performed using carbide tools with varying rake angles (γo = 5o and γo = 30o). It has been found that chip fragmentation increases by increasing the above parameters, i.e. the feed rate fz and the cutting speed vc. The observed chip fragmentation (the quantity of chip fractions) is lower at the tool rake angle γo = 30o. Finally, technological recommendations are formulated based on the quantity of chip fractions generated at particular settings. The results do not unequivocally demonstrate that chip dimensions increase or decrease by increasing the operational parameters of the milling process. In terms of their application, it is vital that machining processes be simultaneously effective and safe.
{"title":"Chip Fragmentation in the Milling of AZ91HP Magnesium Alloy","authors":"J. Kuczmaszewski, I. Zagórski, Olga Gziut, S. Legutko, G. Królczyk","doi":"10.5545/SV-JME.2017.4406","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4406","url":null,"abstract":"This paper presents new approaches to safety assessment in the milling of magnesium alloy. The objective of the study is to determine the effect of milling parameters and end mill geometry on machining safety, defined as the minimum probability of chip self-ignition. The assessment of safety and effectiveness in the milling of magnesium must include analysis of chip fractions formed during the milling process. The paper presents the state of the art of magnesium alloy machinability in terms of chip formation (chip fragmentation). Furthermore, the paper investigates the correlation between the quantity of distinguished chip fractions and variations in the parameters vc and fz as well as in the rake angle γo. In addition, the results of the dimensions of individual chip fractions are reported. The study was conducted on AZ91HP magnesium cast alloy, and the milling process was performed using carbide tools with varying rake angles (γo = 5o and γo = 30o). It has been found that chip fragmentation increases by increasing the above parameters, i.e. the feed rate fz and the cutting speed vc. The observed chip fragmentation (the quantity of chip fractions) is lower at the tool rake angle γo = 30o. Finally, technological recommendations are formulated based on the quantity of chip fractions generated at particular settings. The results do not unequivocally demonstrate that chip dimensions increase or decrease by increasing the operational parameters of the milling process. In terms of their application, it is vital that machining processes be simultaneously effective and safe.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82319554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-30DOI: 10.5545/SV-JME.2017.4450
E. Bagci, Ercument Ugur Yuncuoglu
The high-performance machining of curved surfaces is a highly critical process that is crucial in modern engineering applications. Different methodologies and CAM tools have been developed by manufacturers to improve the efficiency of the sculptured surface milling. The determination of appropriate tool path strategies and milling conditions is crucial in ensuring a high productivity rate, meeting the bettersurface texture values, and lower cutting forces, tool deflection, and surface errors. The objective of this research is to analyse the effect oftool path strategies on dynamic tool deflection, cutting forces, machining time, effective cutter diameter (ECD), cutter/workpiece engagement (CWE) area, instantaneous material removal rate (IMRR), and machining errors in rough machining of a sculptured surface. The B-rep solid modeling-based simulation and the optimization system were developed and integrated with the commercial CAD/CAM software for 3-axis ball-end milling. The experimental results clearly show the influence of the cutter path strategies on machining times and their importance for reducing time needed and, consequently, costs. It was observed that the profiles of deflection, IMRR values, cutting forces, machining errors and ECD values match very well for cutting strategies. Machining strategies employed include various degrees of zig-zag, profiling, and spiral. The conclusion is that the 90° zig-zag strategy provokes the lowest cutting forces, tool deflection, and surface error values. The in-house NC simulation system performed well in determining values and the location of milling form errors on the surface.
{"title":"The Effects of Milling Strategies on Forces, Material Removal Rate, Tool Deflection, and Surface Errors for Rough Machining of Complex Surfaces","authors":"E. Bagci, Ercument Ugur Yuncuoglu","doi":"10.5545/SV-JME.2017.4450","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4450","url":null,"abstract":"The high-performance machining of curved surfaces is a highly critical process that is crucial in modern engineering applications. Different methodologies and CAM tools have been developed by manufacturers to improve the efficiency of the sculptured surface milling. The determination of appropriate tool path strategies and milling conditions is crucial in ensuring a high productivity rate, meeting the bettersurface texture values, and lower cutting forces, tool deflection, and surface errors. The objective of this research is to analyse the effect oftool path strategies on dynamic tool deflection, cutting forces, machining time, effective cutter diameter (ECD), cutter/workpiece engagement (CWE) area, instantaneous material removal rate (IMRR), and machining errors in rough machining of a sculptured surface. The B-rep solid modeling-based simulation and the optimization system were developed and integrated with the commercial CAD/CAM software for 3-axis ball-end milling. The experimental results clearly show the influence of the cutter path strategies on machining times and their importance for reducing time needed and, consequently, costs. It was observed that the profiles of deflection, IMRR values, cutting forces, machining errors and ECD values match very well for cutting strategies. Machining strategies employed include various degrees of zig-zag, profiling, and spiral. The conclusion is that the 90° zig-zag strategy provokes the lowest cutting forces, tool deflection, and surface error values. The in-house NC simulation system performed well in determining values and the location of milling form errors on the surface.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74809509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-30DOI: 10.5545/SV-JME.2016.4230
R. Panowicz, M. Konarzewski, Michał Trypolin
The ConWep method is one of the most frequently used methods of modelling the effects of a blast wave impulse on a structure. The main goal of the study was to assess a TNT equivalent used in this approach. Six different methods to calculate this parameter for different explosive materials and charge shapes were analysed in this paper. The results error was lower than 20 % only when a TNT equivalent based on comparing the pressure impulses was used. This error can be lower only for spherical charges. In addition, for the tested distances (25 cm to 40 cm), TNT equivalents with an error margin of 5 % were assessed.
{"title":"Analysis of Criteria for Determining a TNT Equivalent","authors":"R. Panowicz, M. Konarzewski, Michał Trypolin","doi":"10.5545/SV-JME.2016.4230","DOIUrl":"https://doi.org/10.5545/SV-JME.2016.4230","url":null,"abstract":"The ConWep method is one of the most frequently used methods of modelling the effects of a blast wave impulse on a structure. The main goal of the study was to assess a TNT equivalent used in this approach. Six different methods to calculate this parameter for different explosive materials and charge shapes were analysed in this paper. The results error was lower than 20 % only when a TNT equivalent based on comparing the pressure impulses was used. This error can be lower only for spherical charges. In addition, for the tested distances (25 cm to 40 cm), TNT equivalents with an error margin of 5 % were assessed.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77149100","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-30DOI: 10.5545/SV-JME.2017.4638
S. Oman, M. Nagode
This paper presents an alternative method for calculating the operating forces on bolts in the bolted connections of the end-plate cantilever beams. Since operating force reduces pressure between the joined surfaces the influence of the operating force needs to be considered when determining the clamping force. Therefore, correctly defined operational force on each bolt is a base for all further calculations. To evaluate proposed method, results of four existing analytical methods for calculating the operating forces in the bolted connections of the end-plate cantilever beams are compared with the results of the alternative method and the results gained by finite element analyses. Because finite element analysis take into account all influential parameters it is expected that the results obtained by finite element analyses are a good approximation to reality and can serve as a reference when comparing different analytical methods. It turns out that the results of the proposed method coincide with the results of finite element analyses the most. Only the proposed method correctly determines which bolts in the connection are subjected to the highest additional loads.
{"title":"Bolted Connection of an End-Plate Cantilever Beam: The Distribution of Operating Force","authors":"S. Oman, M. Nagode","doi":"10.5545/SV-JME.2017.4638","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4638","url":null,"abstract":"This paper presents an alternative method for calculating the operating forces on bolts in the bolted connections of the end-plate cantilever beams. Since operating force reduces pressure between the joined surfaces the influence of the operating force needs to be considered when determining the clamping force. Therefore, correctly defined operational force on each bolt is a base for all further calculations. \u0000To evaluate proposed method, results of four existing analytical methods for calculating the operating forces in the bolted connections of the end-plate cantilever beams are compared with the results of the alternative method and the results gained by finite element analyses. Because finite element analysis take into account all influential parameters it is expected that the results obtained by finite element analyses are a good approximation to reality and can serve as a reference when comparing different analytical methods. It turns out that the results of the proposed method coincide with the results of finite element analyses the most. Only the proposed method correctly determines which bolts in the connection are subjected to the highest additional loads.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87597617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-10DOI: 10.5545/SV-JME.2017.4424
Miha Prijatelj, Marko Jerman, H. Orbanić, I. Sabotin, J. Valentinčič, A. Lebar
Abrasive water jet (AWJ) cutting is a versatile technology, but it is limited by relative poor accuracy. The main problem is the unknown diameter of the jet, as there is no device or instrument on the market that would enable a quick and easy measurement of it. With such an instrument the diameter could be regularly measured, nozzle wear monitored and noted offset adjusted. This would greatly improve the quality control of the process and the accuracy of the cut. This paper investigates the usage of a through-beam laser sensor for monitoring jet diameter and nozzle wear. Experiments were performed with five differently worn nozzles, with two different water pressures, with and without abrasive, at different standoff distances and with varying measuring times. Results show that the instrument is capable of monitoring the jet diameter and nozzle wear with an accuracy of ±0.03 mm, but it is very susceptible to the jet’s spray and abrasive sticking to the sensor’s screens. Jet diameter correlated better with the diameter of the focusing nozzle when taking measurements without the abrasive, at high water pressures and at a standoff distance of 1 mm.
{"title":"Determining Focusing Nozzle Wear by Measuring AWJ Diameter","authors":"Miha Prijatelj, Marko Jerman, H. Orbanić, I. Sabotin, J. Valentinčič, A. Lebar","doi":"10.5545/SV-JME.2017.4424","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4424","url":null,"abstract":"Abrasive water jet (AWJ) cutting is a versatile technology, but it is limited by relative poor accuracy. The main problem is the unknown diameter of the jet, as there is no device or instrument on the market that would enable a quick and easy measurement of it. With such an instrument the diameter could be regularly measured, nozzle wear monitored and noted offset adjusted. This would greatly improve the quality control of the process and the accuracy of the cut. This paper investigates the usage of a through-beam laser sensor for monitoring jet diameter and nozzle wear. Experiments were performed with five differently worn nozzles, with two different water pressures, with and without abrasive, at different standoff distances and with varying measuring times. Results show that the instrument is capable of monitoring the jet diameter and nozzle wear with an accuracy of ±0.03 mm, but it is very susceptible to the jet’s spray and abrasive sticking to the sensor’s screens. Jet diameter correlated better with the diameter of the focusing nozzle when taking measurements without the abrasive, at high water pressures and at a standoff distance of 1 mm.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87373513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2017-10-10DOI: 10.5545/SV-JME.2017.4365
A. Piaget, M. Museau, H. Paris
This paper focuses on the manufacturing space homogeneity of the electron beam melting (EBM) technology. An Arcam AB A1 machine is used as tool for experimentations, with titanium (Ti-6Al-4V) as material. The objective of this study is to show the correlation between workpieces geometrical deformations and their position in the manufacturing space. Results show that the position on Z-axis does not affect quality, but there is a strong link in the Z-plane: significant defects appear near the manufacturing space boundaries. First manufactured layers are deformed in the vicinities of the manufacturing space edges. Up to 3 mm of material loss and 8mm of dimensional deformation are measured. Further analyses point that this phenomenon is particularly related to a sintering variation in the powder: there are up to 3 % density difference from the center to borders. To avoid the problem, reduction of the manufacturing space and a supporting strategy are proposed. Defects can also be removed by implementing thermal insulation on the machine or by modifying the beam operation.
本文主要研究了电子束熔化(EBM)技术的制造空间均匀性问题。实验工具为Arcam AB A1型机床，材料为钛(Ti-6Al-4V)。本研究的目的是显示工件几何变形与其在制造空间中的位置之间的相关性。结果表明，在z轴上的位置不影响质量，但在z平面上存在很强的联系:在制造空间边界附近出现明显的缺陷。首先制造的层在制造空间边缘附近变形。测量了高达3mm的材料损失和8mm的尺寸变形。进一步的分析指出，这种现象特别与粉末的烧结变化有关:从中心到边界的密度差高达3%。为了避免这一问题，提出了缩小制造空间和配套策略。缺陷也可以通过在机器上实施隔热或通过修改光束操作来消除。
{"title":"Manufacturing Space Homogeneity in Additive Manufacturing – Electron Beam Melting Case","authors":"A. Piaget, M. Museau, H. Paris","doi":"10.5545/SV-JME.2017.4365","DOIUrl":"https://doi.org/10.5545/SV-JME.2017.4365","url":null,"abstract":"This paper focuses on the manufacturing space homogeneity of the electron beam melting (EBM) technology. An Arcam AB A1 machine is used as tool for experimentations, with titanium (Ti-6Al-4V) as material. The objective of this study is to show the correlation between workpieces geometrical deformations and their position in the manufacturing space. Results show that the position on Z-axis does not affect quality, but there is a strong link in the Z-plane: significant defects appear near the manufacturing space boundaries. First manufactured layers are deformed in the vicinities of the manufacturing space edges. Up to 3 mm of material loss and 8mm of dimensional deformation are measured. Further analyses point that this phenomenon is particularly related to a sintering variation in the powder: there are up to 3 % density difference from the center to borders. To avoid the problem, reduction of the manufacturing space and a supporting strategy are proposed. Defects can also be removed by implementing thermal insulation on the machine or by modifying the beam operation.","PeriodicalId":49472,"journal":{"name":"Strojniski Vestnik-Journal of Mechanical Engineering","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2017-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84155719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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