The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexi...The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexible ball-end body-armor-like abrasive tool(BAAT)can effectively remove micro-convex peaks from the surfaces of brittle materials by employing a high tangential grinding force and a low normal grinding force,thereby achieving nano-level surface roughness and ultra-smooth mirror finishes.However,the surface contact me-chanism,pressure distribution pattern,and grinding force behavior between BAAT and workpiece remain in-adequately understood.This study examines the mechanism of liquid film formation and the distribution pattern of elastohydrodynamic pressure in high-shear and low-pressure grinding areas,drawing on the theories of elastohydrodynamic lubrication,non-Newtonian fluid dynamics,and material mechanics.A high-shear low-pressure grinding force model,which incorporates elastohydrodynamic liquid film thickness and abrasive grain size,was developed.The effects of the main grinding parameters(normal load,spindle rotational speed,and abrasive grain size)on the tangential grinding force were investigated through the processing of lithium niobate crystals using an intelligent precision-grinding system.The experimental results indicated that the relative error between the predicted and experimental values was 10.74%,thereby confirming the accuracy of the grinding force model.This study advances the understanding of elastohydrodynamic lubrication mechanisms in abrasive machining and provides a crucial theoretical foundation for the application of flexible ball-end BAAT.展开更多
Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufact...Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufacturing field.To improve the surface quality of the ground workpiece,a new high-shear and low-pressure grinding wheel,with high ratio of tangential grinding force to normal grinding force,was fabricated for the grinding of selective laser melting(SLM)manufactured Inconel718 alloy.The principle of high-shear and low-pressure grinding process was introduced in detail,which was quite different from the conventional grinding process.The fabrication process of the new grinding wheel was illustrated.A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained.The surface roughness of ground workpiece was reduced to 0.232μm from the initial value of 0.490μm under the optimal grinding conditions.It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM).The capability of the newly developed highshear and low-pressure grinding wheel was validated.展开更多
This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by...This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by the effects of operation conditions such as water content,initial particle size distribution,and the concentrate ratio.The results show that the granule size increased significantly with increasing the granulation time,and the structure of granule can be divided into three types:non-nuclei,single-nuclei,and multi-nuclei.Water promotes the coalescence and growth of particles,and a better granulation performance was obtained at the water content of 8.8wt%under the current raw material conditions.Increasing the nuclei particle ratio led to an increase in average size of granules and permeability of the granules bed,but a decrease in growth index.Besides,with increasing of concentrate ratio,granulation performance such as granule size,bed permeability,and uniformity became worse.展开更多
A material removal mechanism is a prerequisite to maintaining high-quality surfaces for high-shear and low-pressure grinding using body-armor-like grinding wheels(BAGWs).However,the pressure distribution and material ...A material removal mechanism is a prerequisite to maintaining high-quality surfaces for high-shear and low-pressure grinding using body-armor-like grinding wheels(BAGWs).However,the pressure distribution and material removal efficiency for machining brittle materials using BAGWs remain unclear.This research investigated two types of elastic deformations during grinding by analyzing the contact mechanism between BAGWs and the workpiece.Additionally,the model of elastohydrodynamic pressure distribution was refined,and the material removal mechanism for machining brittle materials,incorporating the maximum undeformed chip thickness,was revealed.A material removal rate(MRR)model was established based on Hertzian contact,ductile-brittle transition,and spherical indentation theory.The theoretical model was validated through single-factor experiments utilizing a high-shear and low-pressure grinding experimental platform.At a normal grinding force of 15 N and a grinding speed of 10 m/s,the MRR could reach up to 0.276 mm3/s.The experimental results revealed that the model could accurately predict the MRR under various grinding parameters,with an average prediction error of 8.5%.展开更多
Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guida...Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guidance on the selection and design for the purposes of granulation. Lactose granules were produced using wet granulation with water as a binder. A Kenwood KM070 mixer was used as a standard apparatus and five impeller designs with different shapes and surface areas were used. The efficacy of granulate for- mation was measured by adding an optically sensitive tracer to determine variations in active ingredient content across random samples of granules from the same size classes. It was found that impeller design influenced the homogeneity of the granules and therefore can affect final product performance. The vari- ation in active ingredient content across granules of differing size was also investigated. The results show that small granules were more potent than larger granules,展开更多
There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes...There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes the high-shear granulation process based on relevant process parameters in time and space. The model comprises a coupled-flow-field and population-balance solver and is used to resolve and analyze the effects of mesoscales on the evolution of particle properties. A Diosna high-shear mixer was modelled with microcrystalline cellulose powder as the granulation material. An analysis of the flow-field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations showed the importance of resolving the impeller region, for aggregating systems and systems with breakage. An independent study investigated the time evolution of the flow field by changing the particle properties in three discrete steps that represent pow- der mixing, the initial granulation stage mixing and the late stage granular mixing. The results of the temporal resolution study show clear changes in collision behavior, especially from powder to granular mixing, which indicates the importance of resolving mesoscale phenomena in time and space.展开更多
Wet granulation is one of the most important agglomeration processes,and high-shear granulation(HSG)one of the most employed technologies in the pharmaceutical industry.The most critical process parameters of HSG are ...Wet granulation is one of the most important agglomeration processes,and high-shear granulation(HSG)one of the most employed technologies in the pharmaceutical industry.The most critical process parameters of HSG are discussed in this work.The main concern in scaling up the wet granulation process is the differences between scales,which prevent the particles from having the same experience across all scales.The scale-up of wet granulation processes is commonly divided into two categories:engineering and attribute-based methods.An engineering-based scale-up approach is a strategy based on dimensional analysis and an attribute-based supported on the principles of“equifinality”,where process variables are adjusted to obtain equivalent granule attributes.This work presents the effect of different HSG process parameters on the scale-up,as well as the use of process analytical tools(PAT)and modelling strategies.The aim is to review applied scale-up approaches in HSG and discuss benefits and limitations.It is proven why the scale-up for oral solid pharmaceutical products is still considered a hot topic and a very challenging task for development and engineering teams.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52575516,51875329)Taishan Scholar Special Foundation of Shandong Province(Grant Nos.tstp20240826,tsqn201812064)+2 种基金Shandong Provincial Natural Science Foundation(Grant No.ZR2023ME112)Key Research and Development Project of the Ningxia Hui Autonomous Region(Grant No.2024BEE02019)Innovation Capacity Improvement Programme for High-tech SMEs of Shandong Province(Grant Nos.2022TSGC1333,2022TSGC1261).
文摘The surfaces of brittle materials are susceptible to defects such as scratches,cracks,and chipping during con-ventional grinding processes,which significantly compromise surface quality and service performance.A flexible ball-end body-armor-like abrasive tool(BAAT)can effectively remove micro-convex peaks from the surfaces of brittle materials by employing a high tangential grinding force and a low normal grinding force,thereby achieving nano-level surface roughness and ultra-smooth mirror finishes.However,the surface contact me-chanism,pressure distribution pattern,and grinding force behavior between BAAT and workpiece remain in-adequately understood.This study examines the mechanism of liquid film formation and the distribution pattern of elastohydrodynamic pressure in high-shear and low-pressure grinding areas,drawing on the theories of elastohydrodynamic lubrication,non-Newtonian fluid dynamics,and material mechanics.A high-shear low-pressure grinding force model,which incorporates elastohydrodynamic liquid film thickness and abrasive grain size,was developed.The effects of the main grinding parameters(normal load,spindle rotational speed,and abrasive grain size)on the tangential grinding force were investigated through the processing of lithium niobate crystals using an intelligent precision-grinding system.The experimental results indicated that the relative error between the predicted and experimental values was 10.74%,thereby confirming the accuracy of the grinding force model.This study advances the understanding of elastohydrodynamic lubrication mechanisms in abrasive machining and provides a crucial theoretical foundation for the application of flexible ball-end BAAT.
基金supported by the National Natural Science Foundation of China(Nos.51875329 and 51905322)China postdoctoral Science Foundation(No.2021T140420)+4 种基金Taishan Scholar Special Foundation of Shandong Province(No.tsqn201812064)Shandong Provincial Natural Science Foundation(No.ZR2017MEE050)Shandong Provincial Key Research and Development Project(No.2018GGX103008)Scientific Innovation Project for Young Scientists in Shandong Provincial Universities(No.2019KJB030)Key Research and Development Project of Zibo City(No.2019ZBXC070).
文摘Nickel-based alloy has been widely used due to its outstanding mechanical properties.However,Nickel-based alloy is a typical difficult-to-machine material,which is a great constrain for its application in the manufacturing field.To improve the surface quality of the ground workpiece,a new high-shear and low-pressure grinding wheel,with high ratio of tangential grinding force to normal grinding force,was fabricated for the grinding of selective laser melting(SLM)manufactured Inconel718 alloy.The principle of high-shear and low-pressure grinding process was introduced in detail,which was quite different from the conventional grinding process.The fabrication process of the new grinding wheel was illustrated.A serial of experiments with different processing parameters were carried out to investigate the grinding performance of the developed grinding wheel via analyzing surface roughness and surface morphology of the ground workpiece.The optimal processing parameters of high-shear and low-pressure grinding were obtained.The surface roughness of ground workpiece was reduced to 0.232μm from the initial value of 0.490μm under the optimal grinding conditions.It was found that the initial scratches on the ground workpiece were almost completely removed after the observations with the metalloscopy and the fieldemission scanning electron microscopy(FE-SEM).The capability of the newly developed highshear and low-pressure grinding wheel was validated.
基金financially supported by the National Natural Science Foundation of China (Nos. 51974048 and 52004046)the China Postdoctoral Science Foundation (Nos. 2021T140783 and 2020M673131)the Postdoctoral Science Foundation of Chongqing (No. cstc2020jcyj-bsh X 0030)
文摘This work proposes a novel horizontal high-shear granulator for iron ore granulation before sintering process.The granulation behavior such as growth process and structure of granules were firstly analyzed,followed by the effects of operation conditions such as water content,initial particle size distribution,and the concentrate ratio.The results show that the granule size increased significantly with increasing the granulation time,and the structure of granule can be divided into three types:non-nuclei,single-nuclei,and multi-nuclei.Water promotes the coalescence and growth of particles,and a better granulation performance was obtained at the water content of 8.8wt%under the current raw material conditions.Increasing the nuclei particle ratio led to an increase in average size of granules and permeability of the granules bed,but a decrease in growth index.Besides,with increasing of concentrate ratio,granulation performance such as granule size,bed permeability,and uniformity became worse.
基金supported by the National Natural Science Foundation of China(Grant No.51875329)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2023ME112)+2 种基金the Taishan Scholar Special Foundation of Shandong Province,China(Grant Nos.tstp20240826 and tsqn201812064)the Key Research and Development Project of the Ningxia Hui Autonomous Region,China(Grant No.2024BEE02019)the Shandong Science and Technology Small and Medium-sized Enterprises Innovation Capacity Enhancement Project,China(Grant Nos.2022TSGC1261 and 2022TSGC1333).
文摘A material removal mechanism is a prerequisite to maintaining high-quality surfaces for high-shear and low-pressure grinding using body-armor-like grinding wheels(BAGWs).However,the pressure distribution and material removal efficiency for machining brittle materials using BAGWs remain unclear.This research investigated two types of elastic deformations during grinding by analyzing the contact mechanism between BAGWs and the workpiece.Additionally,the model of elastohydrodynamic pressure distribution was refined,and the material removal mechanism for machining brittle materials,incorporating the maximum undeformed chip thickness,was revealed.A material removal rate(MRR)model was established based on Hertzian contact,ductile-brittle transition,and spherical indentation theory.The theoretical model was validated through single-factor experiments utilizing a high-shear and low-pressure grinding experimental platform.At a normal grinding force of 15 N and a grinding speed of 10 m/s,the MRR could reach up to 0.276 mm3/s.The experimental results revealed that the model could accurately predict the MRR under various grinding parameters,with an average prediction error of 8.5%.
文摘Small mixer impeller design is not tailored for granulation because impellers are intended for a wide range of processes. The aim of this research was to evaluate the performances of several impellers to provide guidance on the selection and design for the purposes of granulation. Lactose granules were produced using wet granulation with water as a binder. A Kenwood KM070 mixer was used as a standard apparatus and five impeller designs with different shapes and surface areas were used. The efficacy of granulate for- mation was measured by adding an optically sensitive tracer to determine variations in active ingredient content across random samples of granules from the same size classes. It was found that impeller design influenced the homogeneity of the granules and therefore can affect final product performance. The vari- ation in active ingredient content across granules of differing size was also investigated. The results show that small granules were more potent than larger granules,
文摘There is a need for mesoscale resolution and coupling between flow-field information and the evolution of particle properties in high-shear granulation. We have developed a modelling framework that com- partmentalizes the high-shear granulation process based on relevant process parameters in time and space. The model comprises a coupled-flow-field and population-balance solver and is used to resolve and analyze the effects of mesoscales on the evolution of particle properties. A Diosna high-shear mixer was modelled with microcrystalline cellulose powder as the granulation material. An analysis of the flow-field solution and compartmentalization allows for a resolution of the stress and collision peak at the impeller blades. Different compartmentalizations showed the importance of resolving the impeller region, for aggregating systems and systems with breakage. An independent study investigated the time evolution of the flow field by changing the particle properties in three discrete steps that represent pow- der mixing, the initial granulation stage mixing and the late stage granular mixing. The results of the temporal resolution study show clear changes in collision behavior, especially from powder to granular mixing, which indicates the importance of resolving mesoscale phenomena in time and space.
基金Fundação para a Ciência e Tecnologia(FCT-MCTES)Portugal,under contract UIDB/00102/2020Bluepharma,Coimbra,Portugal.The authors would like to acknowledge FCT for the financial support to João Gomes(CEECIND/01207/2018).
文摘Wet granulation is one of the most important agglomeration processes,and high-shear granulation(HSG)one of the most employed technologies in the pharmaceutical industry.The most critical process parameters of HSG are discussed in this work.The main concern in scaling up the wet granulation process is the differences between scales,which prevent the particles from having the same experience across all scales.The scale-up of wet granulation processes is commonly divided into two categories:engineering and attribute-based methods.An engineering-based scale-up approach is a strategy based on dimensional analysis and an attribute-based supported on the principles of“equifinality”,where process variables are adjusted to obtain equivalent granule attributes.This work presents the effect of different HSG process parameters on the scale-up,as well as the use of process analytical tools(PAT)and modelling strategies.The aim is to review applied scale-up approaches in HSG and discuss benefits and limitations.It is proven why the scale-up for oral solid pharmaceutical products is still considered a hot topic and a very challenging task for development and engineering teams.
