Pub Date : 2023-10-16DOI: 10.1186/s10033-023-00939-w
Guijian Xiao, Shengwang Zhu, Yi He, Gang Liu, Yuanhe Ni
Abstract The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specific strength and poor thermal conductivity, there are problems such as high cutting force, poor surface integrity, and high cutting temperature during conventional machining. As an advanced processing method with high efficiency and low damage, laser-assisted machining can improve the machinability of titanium alloy. In this study, a picosecond pulse laser-assisted scratching (PPLAS) method considering both the temperature-dependent material properties and ultrashort pulse laser’s characteristics is first proposed. Then, the effects of laser power, scratching depth, and scratching speed on the distribution of stress and temperature field are investigated by simulation. Next, PPLAS experiments are conducted to verify the correctness of the simulation and reveal the removal behavior at various combinations of laser power and scratching depths. Finally, combined with simulated and experimental results, the removal mechanism under the two machining methods is illustrated. Compared with conventional scratching (CS), the tangential grinding force is reduced by more than 60% and the material removal degree is up to 0.948 during PPLAS, while the material removal is still primarily in the form of plastic removal. Grinding debris in CS takes the form of stacked flakes with a “fish scale” surface, whereas it takes the form of broken serrations in PPLAS. This research can provide important guidance for titanium alloy grinding with high surface quality and low surface damage.
{"title":"Thermal-Mechanical Effect and Removal Mechanism of Ti-6Al-4V During Laser-Assisted Grinding","authors":"Guijian Xiao, Shengwang Zhu, Yi He, Gang Liu, Yuanhe Ni","doi":"10.1186/s10033-023-00939-w","DOIUrl":"https://doi.org/10.1186/s10033-023-00939-w","url":null,"abstract":"Abstract The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specific strength and poor thermal conductivity, there are problems such as high cutting force, poor surface integrity, and high cutting temperature during conventional machining. As an advanced processing method with high efficiency and low damage, laser-assisted machining can improve the machinability of titanium alloy. In this study, a picosecond pulse laser-assisted scratching (PPLAS) method considering both the temperature-dependent material properties and ultrashort pulse laser’s characteristics is first proposed. Then, the effects of laser power, scratching depth, and scratching speed on the distribution of stress and temperature field are investigated by simulation. Next, PPLAS experiments are conducted to verify the correctness of the simulation and reveal the removal behavior at various combinations of laser power and scratching depths. Finally, combined with simulated and experimental results, the removal mechanism under the two machining methods is illustrated. Compared with conventional scratching (CS), the tangential grinding force is reduced by more than 60% and the material removal degree is up to 0.948 during PPLAS, while the material removal is still primarily in the form of plastic removal. Grinding debris in CS takes the form of stacked flakes with a “fish scale” surface, whereas it takes the form of broken serrations in PPLAS. This research can provide important guidance for titanium alloy grinding with high surface quality and low surface damage.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136113948","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}
Abstract The hardening on surface of complex profiles such as thread and spline manufactured by cold rolling can effectively improve the mechanical properties and surface quality of rolled parts. The distribution of hardness in superficial layer is closely related to the deformation by rolling. To establish the suitable correlation model for describing the relationship between strain and hardness during cold rolling forming process of complex profiles is helpful to the optimization of rolling parameters and improvement of rolling process. In this study, a physical analog experiment reflecting the uneven deformation during complex-profile rolling process has been extracted and designed, and then the large date set (more than 400 data points) of training samples reflecting the local deformation characteristics of complex-profile rolling have been obtained. Several types of polynomials and power functions were adopted in regression analysis, and the regression correlation models of 45# steel were evaluated by the single-pass and multi-pass physical analog experiments and the complex-profile rolling experiment. The results indicated that the predicting accuracy of polynomial regression model is better in the strain range (i.e., $$varepsilon < 1.2$$ ε<1.2 ) of training samples, and the correlation relationship between strain and hardness out strain range (i.e., $$varepsilon > 1.2$$ ε>1.2 ) of training samples can be well described by power regression model; so the correlation relationship between strain and hardness during complex-profile rolling process of 45# steel can be characterized by a segmented function such as third-order polynomial in the range $$varepsilon < 1.2$$ ε<1.2 and power function with a fitting constant in the range $$varepsilon > 1.2$$ ε>1.2 ; and the predicting error of the regression model by segmented function is less than 10%.
{"title":"Relationship between Hardness and Deformation during Cold Rolling Process of Complex Profiles","authors":"Dawei Zhang, Linghao Hu, Bingkun Liu, Shengdun Zhao","doi":"10.1186/s10033-023-00950-1","DOIUrl":"https://doi.org/10.1186/s10033-023-00950-1","url":null,"abstract":"Abstract The hardening on surface of complex profiles such as thread and spline manufactured by cold rolling can effectively improve the mechanical properties and surface quality of rolled parts. The distribution of hardness in superficial layer is closely related to the deformation by rolling. To establish the suitable correlation model for describing the relationship between strain and hardness during cold rolling forming process of complex profiles is helpful to the optimization of rolling parameters and improvement of rolling process. In this study, a physical analog experiment reflecting the uneven deformation during complex-profile rolling process has been extracted and designed, and then the large date set (more than 400 data points) of training samples reflecting the local deformation characteristics of complex-profile rolling have been obtained. Several types of polynomials and power functions were adopted in regression analysis, and the regression correlation models of 45# steel were evaluated by the single-pass and multi-pass physical analog experiments and the complex-profile rolling experiment. The results indicated that the predicting accuracy of polynomial regression model is better in the strain range (i.e., $$varepsilon < 1.2$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mi>ε</mml:mi> <mml:mo><</mml:mo> <mml:mn>1.2</mml:mn> </mml:mrow> </mml:math> ) of training samples, and the correlation relationship between strain and hardness out strain range (i.e., $$varepsilon > 1.2$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mi>ε</mml:mi> <mml:mo>></mml:mo> <mml:mn>1.2</mml:mn> </mml:mrow> </mml:math> ) of training samples can be well described by power regression model; so the correlation relationship between strain and hardness during complex-profile rolling process of 45# steel can be characterized by a segmented function such as third-order polynomial in the range $$varepsilon < 1.2$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mi>ε</mml:mi> <mml:mo><</mml:mo> <mml:mn>1.2</mml:mn> </mml:mrow> </mml:math> and power function with a fitting constant in the range $$varepsilon > 1.2$$ <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\"> <mml:mrow> <mml:mi>ε</mml:mi> <mml:mo>></mml:mo> <mml:mn>1.2</mml:mn> </mml:mrow> </mml:math> ; and the predicting error of the regression model by segmented function is less than 10%.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114289","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 : 2023-10-16DOI: 10.1186/s10033-023-00946-x
Qunbao Xiao, Min Wan, Xuebin Qin
Abstract Nonlinear friction is a dominant factor affecting the control accuracy of CNC machine tools. This paper proposes a friction pre-compensation method for CNC machine tools through constructing a nonlinear model predictive scheme. The nonlinear friction-induced tracking error is firstly modeled and then utilized to establish the nonlinear model predictive scheme, which is subsequently used to optimize the compensation signal by treating the friction-induced tracking error as the optimization objective. During the optimization procedure, the derivative of compensation signal is constrained to avoid vibration of machine tools. In contrast to other existing approaches, the proposed method only needs the parameters of Stribeck friction model and an additional tuning parameter, while finely identifying the parameters related to the pre-sliding phenomenon is not required. As a result, it greatly facilitates the practical applicability. Both air cutting and real cutting experiments conducted on an in-house developed open-architecture CNC machine tool prove that the proposed method can reduce the tracking errors by more than 56%, and reduce the contour errors by more than 50%.
{"title":"Pre-compensation of Friction for CNC Machine Tools through Constructing a Nonlinear Model Predictive Scheme","authors":"Qunbao Xiao, Min Wan, Xuebin Qin","doi":"10.1186/s10033-023-00946-x","DOIUrl":"https://doi.org/10.1186/s10033-023-00946-x","url":null,"abstract":"Abstract Nonlinear friction is a dominant factor affecting the control accuracy of CNC machine tools. This paper proposes a friction pre-compensation method for CNC machine tools through constructing a nonlinear model predictive scheme. The nonlinear friction-induced tracking error is firstly modeled and then utilized to establish the nonlinear model predictive scheme, which is subsequently used to optimize the compensation signal by treating the friction-induced tracking error as the optimization objective. During the optimization procedure, the derivative of compensation signal is constrained to avoid vibration of machine tools. In contrast to other existing approaches, the proposed method only needs the parameters of Stribeck friction model and an additional tuning parameter, while finely identifying the parameters related to the pre-sliding phenomenon is not required. As a result, it greatly facilitates the practical applicability. Both air cutting and real cutting experiments conducted on an in-house developed open-architecture CNC machine tool prove that the proposed method can reduce the tracking errors by more than 56%, and reduce the contour errors by more than 50%.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114291","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}
Abstract Fast and accurate measurement of the volume of earthmoving materials is of great significance for the real-time evaluation of loader operation efficiency and the realization of autonomous operation. Existing methods for volume measurement, such as total station-based methods, cannot measure the volume in real time, while the bucket-based method also has the disadvantage of poor universality. In this study, a fast estimation method for a loader’s shovel load volume by 3D reconstruction of material piles is proposed. First, a dense stereo matching method (QORB–MAPM) was proposed by integrating the improved quadtree ORB algorithm (QORB) and the maximum a posteriori probability model (MAPM), which achieves fast matching of feature points and dense 3D reconstruction of material piles. Second, the 3D point cloud model of the material piles before and after shoveling was registered and segmented to obtain the 3D point cloud model of the shoveling area, and the Alpha-shape algorithm of Delaunay triangulation was used to estimate the volume of the 3D point cloud model. Finally, a shovel loading volume measurement experiment was conducted under loose-soil working conditions. The results show that the shovel loading volume estimation method (QORB–MAPM VE) proposed in this study has higher estimation accuracy and less calculation time in volume estimation and bucket fill factor estimation, and it has significant theoretical research and engineering application value.
{"title":"Fast Estimation of Loader’s Shovel Load Volume by 3D Reconstruction of Material Piles","authors":"Binyun Wu, Shaojie Wang, Haojing Lin, Shijiang Li, Liang Hou","doi":"10.1186/s10033-023-00945-y","DOIUrl":"https://doi.org/10.1186/s10033-023-00945-y","url":null,"abstract":"Abstract Fast and accurate measurement of the volume of earthmoving materials is of great significance for the real-time evaluation of loader operation efficiency and the realization of autonomous operation. Existing methods for volume measurement, such as total station-based methods, cannot measure the volume in real time, while the bucket-based method also has the disadvantage of poor universality. In this study, a fast estimation method for a loader’s shovel load volume by 3D reconstruction of material piles is proposed. First, a dense stereo matching method (QORB–MAPM) was proposed by integrating the improved quadtree ORB algorithm (QORB) and the maximum a posteriori probability model (MAPM), which achieves fast matching of feature points and dense 3D reconstruction of material piles. Second, the 3D point cloud model of the material piles before and after shoveling was registered and segmented to obtain the 3D point cloud model of the shoveling area, and the Alpha-shape algorithm of Delaunay triangulation was used to estimate the volume of the 3D point cloud model. Finally, a shovel loading volume measurement experiment was conducted under loose-soil working conditions. The results show that the shovel loading volume estimation method (QORB–MAPM VE) proposed in this study has higher estimation accuracy and less calculation time in volume estimation and bucket fill factor estimation, and it has significant theoretical research and engineering application value.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"145 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854584","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 : 2023-10-12DOI: 10.1186/s10033-023-00941-2
Mingcong Li, Shudong Zhao, Heng Li, Yun Huang, Lai Zou, Wenxi Wang
Abstract Improved energy utilisation, precision, and quality are critical in the current trend of low-carbon green manufacturing. In this study, three abrasive belts were prepared at various wear stages and characterised quantitatively. The effects of abrasive belt wear on the specific grinding energy partition were investigated by evaluating robotic belt grinding of titanium plates. A specific grinding energy model based on subdivided tangential forces of cutting and sliding was developed for investigating specific energy and energy utilisation coefficient E UC . The surface morphology and Abbott–Firestone curves of the belts were introduced to analyse the experimental findings from the perspective of the micro cutting behaviour. The specific grinding energy increased with abrasive belt wear, especially when the belt was near the end of its life. Moreover, the belt wear could lead to a predominance change of sliding and chip formation energy. The highest E UC was observed in the middle of the belt life because of its retained sharp cutting edge and uniform distribution of the grit protrusion height. This study provides guidance for balancing the energy consumption and energy utilization efficiency of belt grinding.
{"title":"On Energy Assessment of Titanium Alloys Belt Grinding Involving Abrasive Wear Effects","authors":"Mingcong Li, Shudong Zhao, Heng Li, Yun Huang, Lai Zou, Wenxi Wang","doi":"10.1186/s10033-023-00941-2","DOIUrl":"https://doi.org/10.1186/s10033-023-00941-2","url":null,"abstract":"Abstract Improved energy utilisation, precision, and quality are critical in the current trend of low-carbon green manufacturing. In this study, three abrasive belts were prepared at various wear stages and characterised quantitatively. The effects of abrasive belt wear on the specific grinding energy partition were investigated by evaluating robotic belt grinding of titanium plates. A specific grinding energy model based on subdivided tangential forces of cutting and sliding was developed for investigating specific energy and energy utilisation coefficient E UC . The surface morphology and Abbott–Firestone curves of the belts were introduced to analyse the experimental findings from the perspective of the micro cutting behaviour. The specific grinding energy increased with abrasive belt wear, especially when the belt was near the end of its life. Moreover, the belt wear could lead to a predominance change of sliding and chip formation energy. The highest E UC was observed in the middle of the belt life because of its retained sharp cutting edge and uniform distribution of the grit protrusion height. This study provides guidance for balancing the energy consumption and energy utilization efficiency of belt grinding.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135969565","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 : 2023-10-12DOI: 10.1186/s10033-023-00937-y
Cong Mao, Jiali Wang, Mingjun Zhang, Xincheng Wang, Yuanqiang Luo, Weidong Tang, Kun Tang, Zhuming Bi, Yongle Hu, Zhenheng Lin
Abstract The ability to predict a grinding force is important to control, monitor, and optimize the grinding process. Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding process. This paper aimed to establish a single-grit cutting force model to predict the ploughing, friction and cutting forces in a grinding process. It took into the consideration of actual topography of the grinding wheel, and a theoretical grinding force model for grinding hardened AISI 52100 by the wheel with orderly-micro-grooves was proposed. The model was innovative in the sense that it represented the random thickness of undeformed chips by a probabilistic expression, and it reflected the microstructure characteristics of the structured wheel explicitly. Note that the microstructure depended on the randomness of the protruding heights and distribution density of the grits over the wheel. The proposed force prediction model was validated by surface grinding experiments, and the results showed (1) a good agreement of the predicted and measured forces and (2) a good agreement of the changes of the grinding forces along with the changes of grinding parameters in the prediction model and experiments. This research proposed a theoretical grinding force model of an electroplated grinding wheel with orderly-micro-grooves which is accurate, reliable and effective in predicting grinding forces.
{"title":"Prediction of Grinding Force by an Electroplated Grinding Wheel with Orderly-Micro-Grooves","authors":"Cong Mao, Jiali Wang, Mingjun Zhang, Xincheng Wang, Yuanqiang Luo, Weidong Tang, Kun Tang, Zhuming Bi, Yongle Hu, Zhenheng Lin","doi":"10.1186/s10033-023-00937-y","DOIUrl":"https://doi.org/10.1186/s10033-023-00937-y","url":null,"abstract":"Abstract The ability to predict a grinding force is important to control, monitor, and optimize the grinding process. Few theoretical models were developed to predict grinding forces when a structured wheel was used in a grinding process. This paper aimed to establish a single-grit cutting force model to predict the ploughing, friction and cutting forces in a grinding process. It took into the consideration of actual topography of the grinding wheel, and a theoretical grinding force model for grinding hardened AISI 52100 by the wheel with orderly-micro-grooves was proposed. The model was innovative in the sense that it represented the random thickness of undeformed chips by a probabilistic expression, and it reflected the microstructure characteristics of the structured wheel explicitly. Note that the microstructure depended on the randomness of the protruding heights and distribution density of the grits over the wheel. The proposed force prediction model was validated by surface grinding experiments, and the results showed (1) a good agreement of the predicted and measured forces and (2) a good agreement of the changes of the grinding forces along with the changes of grinding parameters in the prediction model and experiments. This research proposed a theoretical grinding force model of an electroplated grinding wheel with orderly-micro-grooves which is accurate, reliable and effective in predicting grinding forces.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136014254","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 : 2023-10-11DOI: 10.1186/s10033-023-00919-0
Caiyi Liu, Shicheng Liang, Yan Peng, Jianliang Sun, Carlo Mapelli, Silvia Barella, Andrea Gruttadauria, Marco Belfi, Ludovica Rovatti
Abstract Bridge steel has been widely used in recent years for its excellent performance. Understanding the high-temperature Dynamic Recrystallization (DRX) behavior of high-performance bridge steel plays an important role in guiding the thermomechanical processing process. In the present study, the hot deformation behavior of Q370qE bridge steel was investigated by hot compression tests conducted on a Gleeble 3800-GTC thermal-mechanical physical simulation system at temperatures ranging from 900 ℃ to 1100 ℃ and strain rates ranging from 0.01 s −1 to 10 s −1 . The obtained results were used to plot the true stress-strain and work-hardening rate curves of the experimental steel, with the latter curves used to determine the critical strains for the initiation of DRX. The Zener-Hollomon equation was subsequently applied to establish the correspondence between temperature and strain rate during the high-temperature plastic deformation of bridge steel. In terms of the DRX volume fraction solution, a new method for establishing DRX volume fraction was proposed based on two theoretical models. The good weathering and corrosion resistance of bridge steel lead to difficulties in microstructure etching. To solve this, the MTEX technology was used to further develop EBSD data to characterize the original microstructure of Q370qE bridge steel. This paper lays the theoretical foundation for studying the DRX behavior of Q370qE bridge steel.
{"title":"Dynamic Recrystallization Behavior of Q370qE Bridge Steel","authors":"Caiyi Liu, Shicheng Liang, Yan Peng, Jianliang Sun, Carlo Mapelli, Silvia Barella, Andrea Gruttadauria, Marco Belfi, Ludovica Rovatti","doi":"10.1186/s10033-023-00919-0","DOIUrl":"https://doi.org/10.1186/s10033-023-00919-0","url":null,"abstract":"Abstract Bridge steel has been widely used in recent years for its excellent performance. Understanding the high-temperature Dynamic Recrystallization (DRX) behavior of high-performance bridge steel plays an important role in guiding the thermomechanical processing process. In the present study, the hot deformation behavior of Q370qE bridge steel was investigated by hot compression tests conducted on a Gleeble 3800-GTC thermal-mechanical physical simulation system at temperatures ranging from 900 ℃ to 1100 ℃ and strain rates ranging from 0.01 s −1 to 10 s −1 . The obtained results were used to plot the true stress-strain and work-hardening rate curves of the experimental steel, with the latter curves used to determine the critical strains for the initiation of DRX. The Zener-Hollomon equation was subsequently applied to establish the correspondence between temperature and strain rate during the high-temperature plastic deformation of bridge steel. In terms of the DRX volume fraction solution, a new method for establishing DRX volume fraction was proposed based on two theoretical models. The good weathering and corrosion resistance of bridge steel lead to difficulties in microstructure etching. To solve this, the MTEX technology was used to further develop EBSD data to characterize the original microstructure of Q370qE bridge steel. This paper lays the theoretical foundation for studying the DRX behavior of Q370qE bridge steel.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136062868","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 : 2023-10-02DOI: 10.1186/s10033-023-00908-3
Shihua Li, Sen Wang, Haoran Li, Yongjie Wang, Shuang Chen
Abstract In order to solve the problem of weak stiffness of the existing fully decoupled parallel mechanism, a new synthesis method of fully decoupled three translational (3T) parallel mechanisms (PMs) with closed-loop units and high stiffness is proposed based on screw theory. Firstly, a new criterion for the full decoupled of PMs is presented that the reciprocal product of the transmission wrench screw matrix and the output twist screw matrix of PMs is a diagonal matrix, and all elements on the main diagonal are nonzero constants. The forms of the transmission wrench screws are determined by the criterion. Secondly, the forms of the actuated and unactuated screws can be obtained according to their relationships with the transmission wrench screws. The basic decoupled limbs are generated by combination of the above actuated and unactuated screws. Finally, a closed-loop units construction method is investigated to apply the decoupled mechanisms in a better way on the high stiffness occasion. The closed-loop units are constructed in the basic decoupled limbs to generate a high-stiffness fully decoupled 3T PM. Kinematic and stiffness analyses show that the Jacobian matrix is a diagonal matrix, and the stiffness is obviously higher than that of the coupling mechanisms, which verifies the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in vehicle durability test platform.
{"title":"Type Synthesis of Fully Decoupled Three Translational Parallel Mechanism with Closed-Loop Units and High Stiffness","authors":"Shihua Li, Sen Wang, Haoran Li, Yongjie Wang, Shuang Chen","doi":"10.1186/s10033-023-00908-3","DOIUrl":"https://doi.org/10.1186/s10033-023-00908-3","url":null,"abstract":"Abstract In order to solve the problem of weak stiffness of the existing fully decoupled parallel mechanism, a new synthesis method of fully decoupled three translational (3T) parallel mechanisms (PMs) with closed-loop units and high stiffness is proposed based on screw theory. Firstly, a new criterion for the full decoupled of PMs is presented that the reciprocal product of the transmission wrench screw matrix and the output twist screw matrix of PMs is a diagonal matrix, and all elements on the main diagonal are nonzero constants. The forms of the transmission wrench screws are determined by the criterion. Secondly, the forms of the actuated and unactuated screws can be obtained according to their relationships with the transmission wrench screws. The basic decoupled limbs are generated by combination of the above actuated and unactuated screws. Finally, a closed-loop units construction method is investigated to apply the decoupled mechanisms in a better way on the high stiffness occasion. The closed-loop units are constructed in the basic decoupled limbs to generate a high-stiffness fully decoupled 3T PM. Kinematic and stiffness analyses show that the Jacobian matrix is a diagonal matrix, and the stiffness is obviously higher than that of the coupling mechanisms, which verifies the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in vehicle durability test platform.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135828310","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 : 2023-09-25DOI: 10.1186/s10033-023-00944-z
Kun Tang, Wangping Ou, Cong Mao, Jie Liang, Moke Zhang, Mingjun Zhang, Yongle Hu
Abstract Single-crystal silicon carbide (SiC) has been widely applied in the military and civil fields because of its excellent physical and chemical properties. However, as is typical in hard-to-machine materials, the good mechanical properties result in surface defects and subsurface damage during precision or ultraprecision machining. In this study, single- and double-varied-load nanoscratch tests were systematically performed on single-crystal 4H-SiC using a nanoindenter system with a Berkovich indenter. The material removal characteristics and cracks under different planes, indenter directions, normal loading rates, and scratch intervals were analyzed using SEM, FIB, and a 3D profilometer, and the mechanisms of material removal and crack propagation were studied. The results showed that the Si-plane of the single-crystal 4H-SiC and edge forward indenter direction are most suitable for material removal and machining. The normal loading rate had little effect on the scratch depth, but a lower loading rate increased the ductile region and critical depth of transition. Additionally, the crack interaction and fluctuation of the depth-distance curves of the second scratch weakened with an increase in the scratch interval, the status of scratches and chips changed, and the comprehensive effects of the propagation and interaction of the three cracks resulted in material fractures and chip accumulation. The calculated and experimental values of the median crack depth also showed good consistency and relativity. Therefore, this study provides an important reference for the high-efficiency and precision machining of single-crystal SiC to ensure high accuracy and a long service life.
{"title":"Material Removal Characteristics of Single-Crystal 4H-SiC Based on Varied-Load Nanoscratch Tests","authors":"Kun Tang, Wangping Ou, Cong Mao, Jie Liang, Moke Zhang, Mingjun Zhang, Yongle Hu","doi":"10.1186/s10033-023-00944-z","DOIUrl":"https://doi.org/10.1186/s10033-023-00944-z","url":null,"abstract":"Abstract Single-crystal silicon carbide (SiC) has been widely applied in the military and civil fields because of its excellent physical and chemical properties. However, as is typical in hard-to-machine materials, the good mechanical properties result in surface defects and subsurface damage during precision or ultraprecision machining. In this study, single- and double-varied-load nanoscratch tests were systematically performed on single-crystal 4H-SiC using a nanoindenter system with a Berkovich indenter. The material removal characteristics and cracks under different planes, indenter directions, normal loading rates, and scratch intervals were analyzed using SEM, FIB, and a 3D profilometer, and the mechanisms of material removal and crack propagation were studied. The results showed that the Si-plane of the single-crystal 4H-SiC and edge forward indenter direction are most suitable for material removal and machining. The normal loading rate had little effect on the scratch depth, but a lower loading rate increased the ductile region and critical depth of transition. Additionally, the crack interaction and fluctuation of the depth-distance curves of the second scratch weakened with an increase in the scratch interval, the status of scratches and chips changed, and the comprehensive effects of the propagation and interaction of the three cracks resulted in material fractures and chip accumulation. The calculated and experimental values of the median crack depth also showed good consistency and relativity. Therefore, this study provides an important reference for the high-efficiency and precision machining of single-crystal SiC to ensure high accuracy and a long service life.","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135859652","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 : 2023-09-25DOI: 10.1186/s10033-023-00947-w
Changhe Li, Yanbin Zhang, Shubham Sharma
{"title":"Enhanced Heat Transfer Technology Based on Emission Reduction and Carbon Reduction in Cutting and Grinding","authors":"Changhe Li, Yanbin Zhang, Shubham Sharma","doi":"10.1186/s10033-023-00947-w","DOIUrl":"https://doi.org/10.1186/s10033-023-00947-w","url":null,"abstract":"","PeriodicalId":10115,"journal":{"name":"Chinese Journal of Mechanical Engineering","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135769436","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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