Pub Date : 2024-10-18DOI: 10.1016/j.precisioneng.2024.10.010
Daniele Gottini , Giovanni Scimia , Niccolò Grossi , Antonio Scippa
Aluminum is the material of choice for the majority of aerospace components, and, in the past few years, its application has been extended also to the mirrors of space telescopes because of the improved thermal behavior and the possibility to build the entire telescope with the same material. However, the low elastic modulus of such material, combined with the extremely tight tolerances of optical applications, make the production of these components very challenging and, usually, based on a trial-and-error approach. This paper presents a structured methodology for the prediction of the results of manufacturing in Single Point Diamond Turning of optical components, both in terms of absolute deformation as well as optical aberrations (via Zernike polynomials). All the most significant parameters acting on the workpiece have been simulated and combined. The proposed approach has been experimental validated on an actual aluminum mirror, proving its good accuracy (<5 % rms error). While some improvement can be performed to better match the experimental data in terms of Zernike coefficients, especially for non-symmetric aberrations, this paper forms the basis for an off-machine optimization of the SPDT process, drastically reducing the trial-and-error efforts.
{"title":"Deformation and optical aberration prediction in ultra-precision Single Point Diamond Turning of optical components","authors":"Daniele Gottini , Giovanni Scimia , Niccolò Grossi , Antonio Scippa","doi":"10.1016/j.precisioneng.2024.10.010","DOIUrl":"10.1016/j.precisioneng.2024.10.010","url":null,"abstract":"<div><div>Aluminum is the material of choice for the majority of aerospace components, and, in the past few years, its application has been extended also to the mirrors of space telescopes because of the improved thermal behavior and the possibility to build the entire telescope with the same material. However, the low elastic modulus of such material, combined with the extremely tight tolerances of optical applications, make the production of these components very challenging and, usually, based on a trial-and-error approach. This paper presents a structured methodology for the prediction of the results of manufacturing in Single Point Diamond Turning of optical components, both in terms of absolute deformation as well as optical aberrations (via Zernike polynomials). All the most significant parameters acting on the workpiece have been simulated and combined. The proposed approach has been experimental validated on an actual aluminum mirror, proving its good accuracy (<5 % rms error). While some improvement can be performed to better match the experimental data in terms of Zernike coefficients, especially for non-symmetric aberrations, this paper forms the basis for an off-machine optimization of the SPDT process, drastically reducing the trial-and-error efforts.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 489-498"},"PeriodicalIF":3.5,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-16DOI: 10.1016/j.precisioneng.2024.10.008
Guangxi Li , Zhizhen Ren , Wei Yue , Haitao Liu
Robot welding with redundant kinematics demands precise coordination of the welding path and redundant axis motion for stable operation. This paper introduces an effective G3 continuous path planning approach for a 6-DOF friction stir welding robot, integrating redundant axis motion to enhance welding stability and quality. The method encompasses a two-pronged strategy: a five-axis path corner smoothing technique and a motion synchronization strategy. Initially, a robust toolpath preprocessing algorithm is presented to mitigate curvature extremities of the inserted smoothing curves within predefined error limits. Subsequently, leveraging G3 continuity criteria, a B-spline-based smoothing method is advanced for refining tool position and orientation paths, with an analytical determination of spline control points facilitated by an explicit smoothing error expression. An effective motion synchronization technique is then proposed, which formulates the tool position, tool orientation, and redundant axis path as explicit functions of the position path arc length. The effectiveness of the proposed method is demonstrated through simulations and experiments on a robot welding platform, with the integration of a jerk-continuous feedrate profile for smooth motion execution. The findings indicate a significant improvement in robotic welding quality by integrating the proposed path planning method with existing workpiece posture optimization techniques.
采用冗余运动学的机器人焊接需要精确协调焊接路径和冗余轴运动，以实现稳定运行。本文为 6-DOF 搅拌摩擦焊接机器人介绍了一种有效的 G3 连续路径规划方法，该方法整合了冗余轴运动以提高焊接稳定性和质量。该方法包括双管齐下的策略：五轴路径拐角平滑技术和运动同步策略。首先，提出了一种稳健的工具路径预处理算法，以在预定误差范围内减轻插入平滑曲线的曲率极值。随后，利用 G3 连续性标准，提出了一种基于 B 样条的平滑方法，用于细化刀具位置和方向路径，并通过明确的平滑误差表达式来分析确定样条控制点。然后提出了一种有效的运动同步技术，该技术将刀具位置、刀具方向和冗余轴路径表述为位置路径弧长的显式函数。通过在机器人焊接平台上进行仿真和实验，证明了所提方法的有效性。研究结果表明，通过将所提出的路径规划方法与现有的工件姿态优化技术相结合，机器人焊接质量得到了显著提高。
{"title":"An effective path planning approach for robot welding considering redundant kinematics","authors":"Guangxi Li , Zhizhen Ren , Wei Yue , Haitao Liu","doi":"10.1016/j.precisioneng.2024.10.008","DOIUrl":"10.1016/j.precisioneng.2024.10.008","url":null,"abstract":"<div><div>Robot welding with redundant kinematics demands precise coordination of the welding path and redundant axis motion for stable operation. This paper introduces an effective G<sup>3</sup> continuous path planning approach for a 6-DOF friction stir welding robot, integrating redundant axis motion to enhance welding stability and quality. The method encompasses a two-pronged strategy: a five-axis path corner smoothing technique and a motion synchronization strategy. Initially, a robust toolpath preprocessing algorithm is presented to mitigate curvature extremities of the inserted smoothing curves within predefined error limits. Subsequently, leveraging G<sup>3</sup> continuity criteria, a B-spline-based smoothing method is advanced for refining tool position and orientation paths, with an analytical determination of spline control points facilitated by an explicit smoothing error expression. An effective motion synchronization technique is then proposed, which formulates the tool position, tool orientation, and redundant axis path as explicit functions of the position path arc length. The effectiveness of the proposed method is demonstrated through simulations and experiments on a robot welding platform, with the integration of a jerk-continuous feedrate profile for smooth motion execution. The findings indicate a significant improvement in robotic welding quality by integrating the proposed path planning method with existing workpiece posture optimization techniques.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 462-475"},"PeriodicalIF":3.5,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-15DOI: 10.1016/j.precisioneng.2024.10.007
Weijie Fu , Xiangyv Shen , Xinming Zhang
To facilitate the formation of bifocal aspheric optical surfaces, we present an approach for predicting the surface profile of bifocal aspheric surfaces formed by the gas-liquid interface when an elliptical nozzle gas jet is employed. Through an analysis of the gas flow field morphology emanating from the elliptical nozzle, we inferred the impact of gas jet parameters on the gas-liquid interface surface shape within the core region of the gas jet. By analyzing the variation in the gas flow field morphology emitted from an elliptical nozzle, we deduced the influence patterns of gas jet parameters on the gas-liquid interface surface shape within the gas jet's core region. Theoretical analysis is substantiated by numerical simulations, confirming regular changes in the vertex curvature and conic constant of mirror blanks concerning variations in jet initial velocity and nozzle aspect ratio. A comparison between experimental data and numerical simulation results reveals an average prediction deviation of 0.0083 mm−1 for the vertex curvature and a prediction deviation of 10.7 % for the conic constant, challenging to rectify within numerical simulations. Hence, an empirical model, incorporating jet parameters, is developed based on experimental data to predict the vertex curvature and conic constant of mirror blanks. This model demonstrates an average prediction error of 2.901 × 10−3 mm−1 for the vertex curvature and 7.64 % for the conic constant, surpassing the predictive accuracy of the numerical simulation model.
{"title":"Advances in predicting surface shape changes of mirror blanks through elliptical nozzle gas jet forming","authors":"Weijie Fu , Xiangyv Shen , Xinming Zhang","doi":"10.1016/j.precisioneng.2024.10.007","DOIUrl":"10.1016/j.precisioneng.2024.10.007","url":null,"abstract":"<div><div>To facilitate the formation of bifocal aspheric optical surfaces, we present an approach for predicting the surface profile of bifocal aspheric surfaces formed by the gas-liquid interface when an elliptical nozzle gas jet is employed. Through an analysis of the gas flow field morphology emanating from the elliptical nozzle, we inferred the impact of gas jet parameters on the gas-liquid interface surface shape within the core region of the gas jet. By analyzing the variation in the gas flow field morphology emitted from an elliptical nozzle, we deduced the influence patterns of gas jet parameters on the gas-liquid interface surface shape within the gas jet's core region. Theoretical analysis is substantiated by numerical simulations, confirming regular changes in the vertex curvature and conic constant of mirror blanks concerning variations in jet initial velocity and nozzle aspect ratio. A comparison between experimental data and numerical simulation results reveals an average prediction deviation of 0.0083 mm<sup>−1</sup> for the vertex curvature and a prediction deviation of 10.7 % for the conic constant, challenging to rectify within numerical simulations. Hence, an empirical model, incorporating jet parameters, is developed based on experimental data to predict the vertex curvature and conic constant of mirror blanks. This model demonstrates an average prediction error of 2.901 × 10<sup>−3</sup> mm<sup>−1</sup> for the vertex curvature and 7.64 % for the conic constant, surpassing the predictive accuracy of the numerical simulation model.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 451-461"},"PeriodicalIF":3.5,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The extraction of 3D dimensional measurements based on a limited number of 2D X-ray radiographs of a part would offer a significant speed-up of quality control procedures in industry. However, there are challenges with respect to both measurements and uncertainties. This work addresses these challenges by creating an estimated numerical model of the imaged part on which dimensional measurements can be made. The numerical model is chosen as a parametric deformable model that encodes the expected shape variability of the parts resulting from the manufacturing process. The parameters and uncertainties of the numerical model of the imaged part are estimated by the registration of the computed projections of the model and the observed radiographs without the need of any segmentation. The registration requires the model, the initial parameters, and the observed radiographs. The proposed approach is applied to the inspection of turbine blades manufactured by investment casting, and in particular to the measurement of their wall thickness, which is a critical control. The deformable model consists in partitioning the inner ceramic core into multiple subparts, which may undergo a rigid body motion with respect to the master die. Wall thickness measurements are determined from the estimation of these rigid body motions. To assess the reliability of the proposed procedure, a repeatability study is performed. In addition, wall thickness measurements were compared to corresponding measurements from the surface of the metal boundary obtained by X-ray computed tomography. This surface was determined from a reconstructed tomogram using commercial software. Both analyses show that such measurements are reliable and efficient. Furthermore, residual differences between captured and computed projections reveal localized shape deviations from the CAD model, meaning that despite localized model errors, the approach is operable.
根据数量有限的部件二维 X 射线照片提取三维尺寸测量值，将大大加快工业质量控制程序的速度。然而，在测量和不确定性方面都存在挑战。为了应对这些挑战，这项工作创建了一个成像部件的估计数字模型，并在此基础上进行尺寸测量。数值模型被选为参数化可变形模型，该模型可对制造过程中产生的零件预期形状变化进行编码。成像部件数值模型的参数和不确定性是通过模型的计算投影与观察到的射线照片的配准来估算的，无需进行任何分割。注册需要模型、初始参数和观察到的射线照片。所提出的方法被应用于通过熔模铸造法制造的涡轮叶片的检测，特别是其壁厚的测量，这是一项关键控制。可变形模型包括将内部陶瓷芯分成多个子部分，这些子部分可相对于主模进行刚体运动。壁厚测量是通过对这些刚体运动的估计来确定的。为了评估所建议程序的可靠性，进行了重复性研究。此外，还将壁厚测量值与通过 X 射线计算机断层扫描获得的金属边界表面的相应测量值进行了比较。该表面是使用商业软件通过重建断层图确定的。这两项分析表明，这种测量方法既可靠又高效。此外，捕获投影和计算投影之间的残差显示了局部形状与 CAD 模型的偏差，这意味着尽管存在局部模型误差，但这种方法是可行的。
{"title":"Model-based dimensional NDE from few X-ray radiographs: Application to the evaluation of wall thickness in metallic turbine blades","authors":"Cédric Fragnaud , Clément Remacha , Julián Betancur , Stéphane Roux","doi":"10.1016/j.precisioneng.2024.10.002","DOIUrl":"10.1016/j.precisioneng.2024.10.002","url":null,"abstract":"<div><div>The extraction of 3D dimensional measurements based on a <em>limited</em> number of 2D X-ray radiographs of a part would offer a significant speed-up of quality control procedures in industry. However, there are challenges with respect to both measurements and uncertainties. This work addresses these challenges by creating an estimated numerical model of the imaged part on which dimensional measurements can be made. The numerical model is chosen as a parametric deformable model that encodes the expected shape variability of the parts resulting from the manufacturing process. The parameters and uncertainties of the numerical model of the imaged part are estimated by the registration of the computed projections of the model and the observed radiographs without the need of any segmentation. The registration requires the model, the initial parameters, and the observed radiographs. The proposed approach is applied to the inspection of turbine blades manufactured by investment casting, and in particular to the measurement of their wall thickness, which is a critical control. The deformable model consists in partitioning the inner ceramic core into multiple subparts, which may undergo a rigid body motion with respect to the master die. Wall thickness measurements are determined from the estimation of these rigid body motions. To assess the reliability of the proposed procedure, a repeatability study is performed. In addition, wall thickness measurements were compared to corresponding measurements from the surface of the metal boundary obtained by X-ray computed tomography. This surface was determined from a reconstructed tomogram using commercial software. Both analyses show that such measurements are reliable and efficient. Furthermore, residual differences between captured and computed projections reveal localized shape deviations from the CAD model, meaning that despite localized model errors, the approach is operable.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 536-545"},"PeriodicalIF":3.5,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142572441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-11DOI: 10.1016/j.precisioneng.2024.10.003
Yunsong Du , Tianbao Pan , Chongxin Qiao , Tiemin Li
This paper presents a dynamic and static modeling method for compliant mechanisms based on the dynamic stiffness matrix. Its advantage is that accurate dynamic and static modeling can be established simultaneously in frequency domain. Firstly, the dynamic stiffness matrices of flexure beams/hinges are introduced in detail. To ensure modeling accuracy, the nodes of flexible elements are translated to the research nodes, and the local coordinate system is rotated to make it consistent with the global coordinate system. The translation matrix and the rotation matrix are derived, and then the extended dynamic stiffness matrix of flexible elements is also obtained. Then the displacement of the discrete node and the displacement of the research node are taken as the hybrid state variables, and the dynamic model of the whole mechanism is established in frequency domain. The static model of the whole mechanism can be established by changing the angular frequency value. Eventually, two examples are given, and the proposed method is compared with other theoretical models and finite element analysis (FEA). The results show that this method has high modeling accuracy. It provides a reliable modeling method for dynamic and static performance analysis of compliant mechanisms.
{"title":"A novel mechanical model based on the dynamic stiffness matrix for unified dynamic and static modeling of planar compliant mechanisms","authors":"Yunsong Du , Tianbao Pan , Chongxin Qiao , Tiemin Li","doi":"10.1016/j.precisioneng.2024.10.003","DOIUrl":"10.1016/j.precisioneng.2024.10.003","url":null,"abstract":"<div><div>This paper presents a dynamic and static modeling method for compliant mechanisms based on the dynamic stiffness matrix. Its advantage is that accurate dynamic and static modeling can be established simultaneously in frequency domain. Firstly, the dynamic stiffness matrices of flexure beams/hinges are introduced in detail. To ensure modeling accuracy, the nodes of flexible elements are translated to the research nodes, and the local coordinate system is rotated to make it consistent with the global coordinate system. The translation matrix and the rotation matrix are derived, and then the extended dynamic stiffness matrix of flexible elements is also obtained. Then the displacement of the discrete node and the displacement of the research node are taken as the hybrid state variables, and the dynamic model of the whole mechanism is established in frequency domain. The static model of the whole mechanism can be established by changing the angular frequency value. Eventually, two examples are given, and the proposed method is compared with other theoretical models and finite element analysis (FEA). The results show that this method has high modeling accuracy. It provides a reliable modeling method for dynamic and static performance analysis of compliant mechanisms.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 396-417"},"PeriodicalIF":3.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reducing plastic interactions between abrasive grains and the material being processed improves grinding efficiency and lowers energy consumption. Widening the cutting zone with abrasive grains enhances chip formation and reduces lateral material displacement. This can be achieved by using abrasive microaggregates.
The paper presents an experimental analysis of grinding with modified wheels containing abrasive microaggregates. It examines how these microaggregates impact the grinding wheel's surface microgeometry and material removal efficiency. The study measured changes in the number, surface area, volume, and spacing of active contact areas on the grinding wheel active surface. A comparative analysis using the Shos indicator showed that abrasive microaggregates promote the formation of active areas with wide cutting edges perpendicular to the cutting direction.
Finite element method simulations confirmed that abrasive microaggregates enhance material removal by widening the micro-cutting zone and increasing lateral resistance, which reduces the formation of flashes along the cutting path. The study also assessed how these surface features impact the roughness of the ground surface. A comparative analysis of roughness parameters showed a statistically significant reduction in surface, volume, hybrid, and functional parameters when using grinding wheels with abrasive microaggregates. This analysis was conducted using bootstrap statistical hypothesis tests.
{"title":"Experimental investigation and numerical analysis of material removal efficiency using abrasive microaggregates in grinding processes of Ti6Al4V","authors":"Dariusz Lipiński , Łukasz Rypina , Kamil Banaszek , Robert Tomkowski","doi":"10.1016/j.precisioneng.2024.10.005","DOIUrl":"10.1016/j.precisioneng.2024.10.005","url":null,"abstract":"<div><div>Reducing plastic interactions between abrasive grains and the material being processed improves grinding efficiency and lowers energy consumption. Widening the cutting zone with abrasive grains enhances chip formation and reduces lateral material displacement. This can be achieved by using abrasive microaggregates.</div><div>The paper presents an experimental analysis of grinding with modified wheels containing abrasive microaggregates. It examines how these microaggregates impact the grinding wheel's surface microgeometry and material removal efficiency. The study measured changes in the number, surface area, volume, and spacing of active contact areas on the grinding wheel active surface. A comparative analysis using the Shos indicator showed that abrasive microaggregates promote the formation of active areas with wide cutting edges perpendicular to the cutting direction.</div><div>Finite element method simulations confirmed that abrasive microaggregates enhance material removal by widening the micro-cutting zone and increasing lateral resistance, which reduces the formation of flashes along the cutting path. The study also assessed how these surface features impact the roughness of the ground surface. A comparative analysis of roughness parameters showed a statistically significant reduction in surface, volume, hybrid, and functional parameters when using grinding wheels with abrasive microaggregates. This analysis was conducted using bootstrap statistical hypothesis tests.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 476-488"},"PeriodicalIF":3.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-11DOI: 10.1016/j.precisioneng.2024.10.006
Chenhao Xue, Ningsong Qu
Electrochemical discharge machining (ECDM) has a splendid application potential for machining difficult-to-cut materials. It is a challenge to limit and control the discharge energy and area of DC power supply in ECDM. Owing to the uncertainty and randomness of the position and range of the single discharge, the unpredictable discharges deteriorate the surface quality of the workpiece, alter the size of the inter-electrode gap (IEG), and influence the distribution of the multi-physical fields. Therefore, to regulate the machining state and energy, the ideology of pulse dynamic machining is introduced, and a method of pulse dynamic ECDM utilizing the slotted electrodes is proposed. With the tool electrode rotating, the tube electrode transforms the pure electrochemical machining (pure-ECM) stage and the electrochemical discharge machining (ECDM) stage periodically through the slots at the bottom of it. The machining current waveform, surface roughness and sidewall taper of machined grooves, material removal rate (MRR), and relative tool wear rate (RTWR) are investigated. Additionally, the discharge types of the ECDM are explicitly defined and statistically classified. The experimental results show that the pulse dynamic regulation of hybrid machining using the slotted electrodes is beneficial to regularize the machining current waveform and optimize the machining quality.
{"title":"Pulse dynamic regulation of electrochemical discharge milling by utilizing the slotted tube electrode","authors":"Chenhao Xue, Ningsong Qu","doi":"10.1016/j.precisioneng.2024.10.006","DOIUrl":"10.1016/j.precisioneng.2024.10.006","url":null,"abstract":"<div><div>Electrochemical discharge machining (ECDM) has a splendid application potential for machining difficult-to-cut materials. It is a challenge to limit and control the discharge energy and area of DC power supply in ECDM. Owing to the uncertainty and randomness of the position and range of the single discharge, the unpredictable discharges deteriorate the surface quality of the workpiece, alter the size of the inter-electrode gap (IEG), and influence the distribution of the multi-physical fields. Therefore, to regulate the machining state and energy, the ideology of pulse dynamic machining is introduced, and a method of pulse dynamic ECDM utilizing the slotted electrodes is proposed. With the tool electrode rotating, the tube electrode transforms the pure electrochemical machining (pure-ECM) stage and the electrochemical discharge machining (ECDM) stage periodically through the slots at the bottom of it. The machining current waveform, surface roughness and sidewall taper of machined grooves, material removal rate (MRR), and relative tool wear rate (RTWR) are investigated. Additionally, the discharge types of the ECDM are explicitly defined and statistically classified. The experimental results show that the pulse dynamic regulation of hybrid machining using the slotted electrodes is beneficial to regularize the machining current waveform and optimize the machining quality.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 433-443"},"PeriodicalIF":3.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2024-10-11DOI: 10.1016/j.precisioneng.2024.10.004
Jian Ma , Hongbing Wan , Feng Peng , Hongyu Chen , Chang Chen , Pengqi Chen , Tufa Habtamu Beri , Heng Chen , Kun Ren , Binghai Lyu
In this paper, the polishing mechanism of polycrystalline tungsten has been studied, focusing on the reasons for the appearance of grain steps and the effects of different polishing factors on the polishing effect. The surface morphology and mechanical properties after polishing were analyzed by electron backscatter diffraction, scanning electron microscope, nanoindentation and other characterization tools. Effects of different polishing factors on the polishing effect were also analyzed by orthogonal and single factor experiments. Results show that the effects of abrasive size, polishing pressure, polishing speed, and abrasive concentration on the polishing effectiveness decrease in turn. The optimal polishing parameters obtained by orthogonal experiments are 60 rpm polishing speed, 5.0 μm abrasive size, 5 wt% abrasive concentration, and 30 kPa polishing pressure. In the single factor experiment, with the increase of abrasive size, the height of grain step decreased from 0.5 μm to 0.11 μm, and the surface roughness (Ra) decreases from 11.3 nm to 5.2 nm. Grain anisotropy is the main reason for the appearance of grain steps on the surface after polishing. Different grain orientations lead to different surface mechanical properties. The hardness of high grain step is higher than that of low grain step. In addition, the increase of abrasive size can effectively suppress the grain step phenomenon, thereby improving the surface polishing effect.
{"title":"Study on grain removal characteristics and influencing factors of polycrystalline tungsten during polishing process","authors":"Jian Ma , Hongbing Wan , Feng Peng , Hongyu Chen , Chang Chen , Pengqi Chen , Tufa Habtamu Beri , Heng Chen , Kun Ren , Binghai Lyu","doi":"10.1016/j.precisioneng.2024.10.004","DOIUrl":"10.1016/j.precisioneng.2024.10.004","url":null,"abstract":"<div><div>In this paper, the polishing mechanism of polycrystalline tungsten has been studied, focusing on the reasons for the appearance of grain steps and the effects of different polishing factors on the polishing effect. The surface morphology and mechanical properties after polishing were analyzed by electron backscatter diffraction, scanning electron microscope, nanoindentation and other characterization tools. Effects of different polishing factors on the polishing effect were also analyzed by orthogonal and single factor experiments. Results show that the effects of abrasive size, polishing pressure, polishing speed, and abrasive concentration on the polishing effectiveness decrease in turn. The optimal polishing parameters obtained by orthogonal experiments are 60 rpm polishing speed, 5.0 μm abrasive size, 5 wt% abrasive concentration, and 30 kPa polishing pressure. In the single factor experiment, with the increase of abrasive size, the height of grain step decreased from 0.5 μm to 0.11 μm, and the surface roughness (Ra) decreases from 11.3 nm to 5.2 nm. Grain anisotropy is the main reason for the appearance of grain steps on the surface after polishing. Different grain orientations lead to different surface mechanical properties. The hardness of high grain step is higher than that of low grain step. In addition, the increase of abrasive size can effectively suppress the grain step phenomenon, thereby improving the surface polishing effect.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 499-506"},"PeriodicalIF":3.5,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is difficult for robots to manipulate flexible objects, and adhesive dispensing is one such task. In this task, the adhesive material is pulled by a dispensing robot, which is problematic to predict. In this paper, we propose an analysis-based and a learning-based model to predict the behavior of the adhesive material, and a method to explore the robot trajectory. While analysis-based models consider physical behavior and require less training data, they are limited to specific physical behaviors. Learning-based models, on the other hand, can model many physical behaviors, but require a lot of training data. Finally, we use the predictions of these models to perform experiments and evaluate the differences between the target adhesive trajectory and the actual application results.
{"title":"Trajectory generation for adhesive dispensing robots by modeling of material behavior","authors":"Takayuki Yamabe , Kazuki Takagi , Ryunosuke Yamada , Tokuo Tsuji , Shota Ishikawa , Tomoaki Ozaki , Tatsuhiro Hiramitsu , Hiroaki Seki","doi":"10.1016/j.precisioneng.2024.09.025","DOIUrl":"10.1016/j.precisioneng.2024.09.025","url":null,"abstract":"<div><div>It is difficult for robots to manipulate flexible objects, and adhesive dispensing is one such task. In this task, the adhesive material is pulled by a dispensing robot, which is problematic to predict. In this paper, we propose an analysis-based and a learning-based model to predict the behavior of the adhesive material, and a method to explore the robot trajectory. While analysis-based models consider physical behavior and require less training data, they are limited to specific physical behaviors. Learning-based models, on the other hand, can model many physical behaviors, but require a lot of training data. Finally, we use the predictions of these models to perform experiments and evaluate the differences between the target adhesive trajectory and the actual application results.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 444-450"},"PeriodicalIF":3.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-04DOI: 10.1016/j.precisioneng.2024.09.026
Yan Li , Gang Li , Zhonghou Wang , William Mayfield
Gear shaping causes processing characteristics on gear tooth surfaces (PCGTS), e.g., gear tooth surface deviation (GTSD) and processing textures (PT), which can affect gear meshing performances. Gear shaping simulation is operated to obtain PCGTS with different indexing feeds. An improved contact stiffness method of gear tooth surfaces is developed based on a wedge-shaped contact form to obtain tooth contact stiffness with PT caused by gear shaping. An improved time-varying meshing stiffness (TVMS) method for gears manufactured by gear shaping is developed to calculate TVMS of gears with GTSD and PT under different indexing feed conditions. Effectiveness of the improved TVMS method is validated using the finite element method. Analysis results of the proposed contact stiffness method of gear tooth surfaces indicate that PT caused by gear shaping can aggravate fluctuations of gear tooth contact stress. Analysis results of the proposed TVMS method for gears also indicate that GTSD of gear tooth surfaces caused by gear shaping can reduce their TVMS. The proposed TVMS method of gears can effectively analyze TVMS of gear tooth surfaces via gear shaping and evaluate processing settings of gear shaping to improve gear meshing performances.
{"title":"On gear time-varying meshing stiffness calculation considering indexing feeds and processing characteristics of gear shaping processing","authors":"Yan Li , Gang Li , Zhonghou Wang , William Mayfield","doi":"10.1016/j.precisioneng.2024.09.026","DOIUrl":"10.1016/j.precisioneng.2024.09.026","url":null,"abstract":"<div><div>Gear shaping causes processing characteristics on gear tooth surfaces (PCGTS), e.g., gear tooth surface deviation (GTSD) and processing textures (PT), which can affect gear meshing performances. Gear shaping simulation is operated to obtain PCGTS with different indexing feeds. An improved contact stiffness method of gear tooth surfaces is developed based on a wedge-shaped contact form to obtain tooth contact stiffness with PT caused by gear shaping. An improved time-varying meshing stiffness (TVMS) method for gears manufactured by gear shaping is developed to calculate TVMS of gears with GTSD and PT under different indexing feed conditions. Effectiveness of the improved TVMS method is validated using the finite element method. Analysis results of the proposed contact stiffness method of gear tooth surfaces indicate that PT caused by gear shaping can aggravate fluctuations of gear tooth contact stress. Analysis results of the proposed TVMS method for gears also indicate that GTSD of gear tooth surfaces caused by gear shaping can reduce their TVMS. The proposed TVMS method of gears can effectively analyze TVMS of gear tooth surfaces via gear shaping and evaluate processing settings of gear shaping to improve gear meshing performances.</div></div>","PeriodicalId":54589,"journal":{"name":"Precision Engineering-Journal of the International Societies for Precision Engineering and Nanotechnology","volume":"91 ","pages":"Pages 418-432"},"PeriodicalIF":3.5,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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