The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusio...The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.展开更多
Ultrasonic vibration grinding differs from traditional grinding in terms of its material removal mechanism.The randomness of grain-workpiece interaction in ultrasonic vibration grinding can produce variable chips and ...Ultrasonic vibration grinding differs from traditional grinding in terms of its material removal mechanism.The randomness of grain-workpiece interaction in ultrasonic vibration grinding can produce variable chips and impact the surface roughness of workpiece.However,previous studies used iterative method to calculate the unformed chip thickness(UCT),which has low computational efficiency.In this study,a symbolic difference method is proposed to calculate the UCT.The UCT distributions are obtained to describe the stochastic interaction characteristics of ultrasonic grinding process.Meanwhile,the UCT distribution characteristics under different machining parameters are analyzed.Then,a surface roughness prediction model is established based on the UCT distribution.Finally,the correctness of the model is verified by experiments.This study provides a quick and accurate method for predicting surface roughness in longitudinal ultrasonic vibration grinding.展开更多
The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple ...The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.展开更多
Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for the...Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ratio.However,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low stiffness.Instead,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy machining.In this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of HUVC.First,the kinematics,tool path,and dynamic cutting thickness of HUVC are evaluated.Second,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness model.HUVC can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the system.Finally,comparison experiments are conducted between HUVC and CC processes.The results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting force.In addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC.展开更多
Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottlene...Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difculty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were frst studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of diferent layers of abrasive particles under diferent instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.展开更多
It is extremely important to select appropriate feedrates for the stable machining of parts with ruled surface in modern aviation industrial applications.However,the current studies take too much time to achieve this ...It is extremely important to select appropriate feedrates for the stable machining of parts with ruled surface in modern aviation industrial applications.However,the current studies take too much time to achieve this goal.Therefore,this paper presents an efficient feedrate optimization method for constant peak cutting force in five-axis flank milling process.The solution method of the instantaneous undeformed chip thickness(IUCT)is proposed using least squares theory with the cutter entry angle and feedrate as variables.Based on this method,an explicit analytical expression of the peak cutting force for each cutting point is established.Furthermore,a feedrate scheduling method is developed to quickly solve the appropriate feedrate under constant peak cutting force.To verify the proposed IUCT model,the fitting IUCT is compared with the accuracy data at different feedrates.Additionally,some experiments of five-axis flank milling are conducted to demonstrate the effectiveness of the peak force model and the feedrate scheduling method.And the surface roughness before and after feedrate scheduling is detected.The results show that the proposed feedrate scheduling method can quickly adjust the feedrate and ensure constant peak force during machining.At the same time,the surface quality is kept at a high level.展开更多
In a milling operation, there must be processes of a cutter entering and exiting the workpiece boundary. The cutter exit is usually in the feed direction and the dynamic response is different from that in the normal c...In a milling operation, there must be processes of a cutter entering and exiting the workpiece boundary. The cutter exit is usually in the feed direction and the dynamic response is different from that in the normal cutting process. This paper presents a new time-domain modeling of mechanics and dynamics of the cutter exit process for the slot milling process. The cutter is assumed to exit the workpiece for the first time with one tooth right in the feed direction. The dynamic chip thickness is summed up along the feed direction and compared with the remaining workpiece length in the feed direction to judge whether the cutter is ready to exit the workpiece or not. The developed model is then used for analyzing the cutting force and machining vibration in the cutter exit process.The developed mathematical model is experimentally validated by comparing the simulated forces and vibrations against the measured data collected from real slotting milling tests. The study shows that stable cutting parameters cannot guarantee stable cutting in a cutter exit process and further study can be performed to control the vibration amplitude in this specific process.展开更多
A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cut...A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.展开更多
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...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.展开更多
Grinding operation is a finishing process often employed when high precision and narrow geometric tolerances are required.These requirements can be achieved only if cutting conditions are properly selected,especially ...Grinding operation is a finishing process often employed when high precision and narrow geometric tolerances are required.These requirements can be achieved only if cutting conditions are properly selected,especially the cooling-lubrication technique.In general,grinding is performed in presence of cutting fluid,however,due to the environmental impacts and costs of the conventional coolant delivery technique(flow rates from 4 L/min to 300 L/min),alternative cooling-lubrication techniques have been developed on restriction of the coolants use.Among the several techniques,MQL(minimum quantity of lubricant)technique has received special attention from machining users because of its advantages in terms of surface quality of workpiece and drastic reduction in use of coolant.In this context,this paper evaluated the performance of the MQL technique as compared to the flood coolant in peripheral surface grinding of AISI P100(VP100)steel with conventional aluminum oxide grinding wheel in relation to the surface roughness(Ra and Rz).Input parameters tested were equivalent chip thickness(0.09μm,0.18μm and 0.27μm)and flow rate of the cutting fluid(60 mL/h,150 mL/h and 240 mL/h)of the MQL system.Results showed that the grinding with MQL technique provided lower surface roughness values compared to conventional flood cooling,especially when machining under the intermediary cutting conditions.Also,with exception of heq of 0.09 m,the MQL technique resulted in lower values of Rz parameter as compared to the conventional coolant technique,regardless of the flow rate tested.展开更多
Alumina dispersion-strengthened copper (ADSC), as a representative particle-reinforced metal matrix composite (PRMMC), exhibits superior wear resistance and high strength. However, challenges arise in their processabi...Alumina dispersion-strengthened copper (ADSC), as a representative particle-reinforced metal matrix composite (PRMMC), exhibits superior wear resistance and high strength. However, challenges arise in their processability because of the non-uniform material properties of biphasic materials. In particular, limited research has been conducted on the reinforcement mechanism and behavior of particles during material cutting deformation of PRMMC with nanoscale particles. In this study, a cutting simulation model for ADSC was established, separating the nanoscale reinforcement particles from the matrix. This model was utilized to analyze the interactions among particles, matrix, and tool during the cutting process, providing insights into chip formation and fracture. Particles with high strength and hardness are more prone to storing stress concentrations, anchoring themselves at grain boundaries to resist grain fibration, thereby influencing the stress distribution in the cutting deformation zone. Stress concentration around the particles leads to the formation of discontinuous chips, indicating that ADSC with high-volume fractions of particle (VFP) exhibits low cutting continuity, which is consistent with the results of cutting experiments. The tool tip that is in contact with particles experiences stress concentration, thereby accelerating tool wear. Cutting ADSC with 1.1% VFP results in tool blunting, which increases the radius of cutting edge from 0.5 to 1.9 μm, accompanied with remarkable coating delamination and wear. Simulation results indicate that the minimum uncut chip thickness increases from 0.04 to 0.07 μm as VFP increases from 0.3% to 1.1%. In conjunction with scratch experiments, MUCT increases with the augmentation of VFP. Computational analysis of the specific cutting force indicates that particles contribute to the material’s size effect. The results of this study provide theoretical guidance for practical engineering machining of ADSC, indicating its great importance for the process design of components made from ADSC.展开更多
Brittle materials have been widely employed for industrial applications due to their excellent mechanical, optical, physical and chemical properties. But obtaining smooth and damage-free surface on brittle materials b...Brittle materials have been widely employed for industrial applications due to their excellent mechanical, optical, physical and chemical properties. But obtaining smooth and damage-free surface on brittle materials by traditional machining methods like grinding, lapping and polishing is very costly and extremely time consuming. Ductile mode cutting is a very promising way to achieve high quality and crack-free surfaces of brittle materials. Thus the study of ductile mode cutting of brittle materials has been attracting more and more efforts. This paper provides an overview of ductile mode cutting of brittle materials including ductile nature and plasticity of brittle materials, cutting mechanism, cutting characteris- tics, molecular dynamic simulation, critical undeformed chip thickness, brittle-ductile transition, subsurface damage, as well as a detailed discussion of ductile mode cutting enhancement. It is believed that ductile mode cutting of brittle materials could be achieved when both crack-free and no subsurface damage are obtained simultaneously.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.92160301,92060203,52175415 and 52205475)the Science Center for Gas Turbine Project(Nos.P2022-AB-Ⅳ-002-001 and P2023-B-Ⅳ-003-001)+3 种基金the Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology(No.JSKL2223K01)the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the Henan Science and Technology Public Relations Project(No.212102210445).
文摘The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.
基金supported by the National Key Research and Development Program of China(No.2018YFB2000402)the Open Fund Project of Xinchang Research Institute of Zhejiang University of Technology,and the Fundamental Research Funds for the Universities of Henan Province,China(No.NSFRF200102).
文摘Ultrasonic vibration grinding differs from traditional grinding in terms of its material removal mechanism.The randomness of grain-workpiece interaction in ultrasonic vibration grinding can produce variable chips and impact the surface roughness of workpiece.However,previous studies used iterative method to calculate the unformed chip thickness(UCT),which has low computational efficiency.In this study,a symbolic difference method is proposed to calculate the UCT.The UCT distributions are obtained to describe the stochastic interaction characteristics of ultrasonic grinding process.Meanwhile,the UCT distribution characteristics under different machining parameters are analyzed.Then,a surface roughness prediction model is established based on the UCT distribution.Finally,the correctness of the model is verified by experiments.This study provides a quick and accurate method for predicting surface roughness in longitudinal ultrasonic vibration grinding.
文摘The miniaturisation context leads to the rise of micro-machining processes. Micro-milling is one of the most flexible and fast of them. Although it is based on the same principles as macro-cutting, it is not a simple scaling-down of it. This down-sizing involves new phenomena in the chip formation, such as the minimum chip thickness below which no chip is formed. This paper presents a review of the current state of the art in this field from an experimental and a numerical point of view. A 2D finite element model is then developed to study the influence of the depth of cut on the chip formation. After the model validation in macro-cutting, it highlights the phenomena reported in literature and allows to perform a minimum chip thickness estimation.
基金supported by the Defense Industrial Technology Development Program of China(No.JCKY2018601C209)。
文摘Titanium alloys are widely used in the aviation and aerospace industries due to their unique mechanical and physical properties.Specifically,thin-walled titanium(Ti)cylinders have received increasing attention for their applications as rocket engine casings,aircraft landing gear,and aero-engine hollow shaft due to their observed improvement in the thrust-to-weight ratio.However,the conventional cutting(CC)process is not appropriate for thin-walled Ti cylinders due to its low thermal conductivity,high strength,and low stiffness.Instead,high-speed ultrasonic vibration cutting(HUVC)assisted processing has recently proved highly effective for Ti-alloy machining.In this study,HUVC technology is employed to perform external turning of a thinwalled Ti cylinder,which represents a new application of HUVC.First,the kinematics,tool path,and dynamic cutting thickness of HUVC are evaluated.Second,the phenomenon of mode-coupling chatter is analyzed to determine the effects and mechanism of HUVC by establishing a critical cutting thickness model.HUVC can increase the critical cutting thickness and effectively reduce the average cutting force,thus reducing the energy intake of the system.Finally,comparison experiments are conducted between HUVC and CC processes.The results indicate that the diameter error rate is 10%or less for HUVC and 51%for the CC method due to a 40%reduction in the cutting force.In addition,higher machining precision and better surface roughness are achieved during thin-walled Ti cylinder manufacturing using HUVC.
基金Supported by National Natural Science Foundation of China(Grant Nos.51975305,52105457,and 52205481)the Special Fund of Taishan Scholars Project(Grant No.tsqn202211179)+1 种基金Shandong Provincial Youth Talent Promotion Project(Grant No.SDAST2021qt12)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2023QE057,ZR2022QE028,ZR2021QE116,and ZR2020KE027).
文摘Micro-grinding with a spherical grinding head has been deemed an indispensable method in high-risk surgeries, such as neurosurgery and spine surgery, where bone grinding has long been plagued by the technical bottleneck of mechanical stress-induced crack damage. In response to this challenge, the ultrasound-assisted biological bone micro-grinding novel process with a spherical grinding head has been proposed by researchers. Force modeling is a prerequisite for process parameter determination in orthopedic surgery, and the difculty in establishing and accurately predicting bone micro-grinding force prediction models is due to the geometric distribution of abrasive grains and the dynamic changes in geometry and kinematics during the cutting process. In addressing these critical needs and technical problems, the shape and protrusion heights of the wear particle of the spherical grinding head were frst studied, and the gradual rule of the contact arc length under the action of high-speed rotating ultrasonic vibration was proposed. Second, the mathematical model of the maximum thickness of undeformed chips under ultrasonic vibration of the spherical grinding head was established. Results showed that ultrasonic vibration can reduce the maximum thickness of undeformed chips and increase the range of ductile and bone meal removals, revealing the mechanism of reducing grinding force. Further, the dynamic grinding behavior of diferent layers of abrasive particles under diferent instantaneous interaction states was studied. Finally, a prediction model of micro-grinding force was established in accordance with the relationship between grinding force and cutting depth, revealing the mechanism of micro-grinding force transfer under ultrasonic vibration. The theoretical model’s average deviations are 10.37% in x-axis direction, 6.85% in y-axis direction, and 7.81% in z-axis direction compared with the experimental results. This study provides theoretical guidance and technical support for clinical bone micro-grinding.
基金co-supported by the Major National S&T Program(2017ZX04002001)the Major National S&T Program(2016ZX04004004)。
文摘It is extremely important to select appropriate feedrates for the stable machining of parts with ruled surface in modern aviation industrial applications.However,the current studies take too much time to achieve this goal.Therefore,this paper presents an efficient feedrate optimization method for constant peak cutting force in five-axis flank milling process.The solution method of the instantaneous undeformed chip thickness(IUCT)is proposed using least squares theory with the cutter entry angle and feedrate as variables.Based on this method,an explicit analytical expression of the peak cutting force for each cutting point is established.Furthermore,a feedrate scheduling method is developed to quickly solve the appropriate feedrate under constant peak cutting force.To verify the proposed IUCT model,the fitting IUCT is compared with the accuracy data at different feedrates.Additionally,some experiments of five-axis flank milling are conducted to demonstrate the effectiveness of the peak force model and the feedrate scheduling method.And the surface roughness before and after feedrate scheduling is detected.The results show that the proposed feedrate scheduling method can quickly adjust the feedrate and ensure constant peak force during machining.At the same time,the surface quality is kept at a high level.
基金co-supported by the National Natural Science Foundation of China (Nos. 51305354 and 51611130191)National Basic Research Program of China (No. 2013CB035802)the Fundamental Research Funds for the Central Universities (No. 3102015JCS05002)
文摘In a milling operation, there must be processes of a cutter entering and exiting the workpiece boundary. The cutter exit is usually in the feed direction and the dynamic response is different from that in the normal cutting process. This paper presents a new time-domain modeling of mechanics and dynamics of the cutter exit process for the slot milling process. The cutter is assumed to exit the workpiece for the first time with one tooth right in the feed direction. The dynamic chip thickness is summed up along the feed direction and compared with the remaining workpiece length in the feed direction to judge whether the cutter is ready to exit the workpiece or not. The developed model is then used for analyzing the cutting force and machining vibration in the cutter exit process.The developed mathematical model is experimentally validated by comparing the simulated forces and vibrations against the measured data collected from real slotting milling tests. The study shows that stable cutting parameters cannot guarantee stable cutting in a cutter exit process and further study can be performed to control the vibration amplitude in this specific process.
基金co-supported by Open National Natural Science Foundation of China(No.51005183)National Science and Technology Major Project(No.2011ZX04016031)China Postdoctoral Science Foundation(No.2012M521804)
文摘A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.
基金Supported by National Natural Science Foundation of China(Grant Nos.52275405,52275311,51875050)Hunan Provincial Key Research and Development Program(Grant No.2021GK2021).
文摘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.
基金This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—Brasil(CAPES)—Finance Code 001The authors are grateful too to the FAPEMIG and the Post Graduate Program of Mechanical Engineering of UFU for financial support.Authors are also grateful to Villares Metals(Brazil)+1 种基金Saint Gobain Abrasives for supporting this work with workpiece material and wheel.One of authors thanks CNPq(PQ 2013 Project No.308067/2013)for the research scholarship and FAPEMIG project process No.PPM-00265-13 for financial supportThe authors are also thankful to ABCM for transferring the copyright of the article.
文摘Grinding operation is a finishing process often employed when high precision and narrow geometric tolerances are required.These requirements can be achieved only if cutting conditions are properly selected,especially the cooling-lubrication technique.In general,grinding is performed in presence of cutting fluid,however,due to the environmental impacts and costs of the conventional coolant delivery technique(flow rates from 4 L/min to 300 L/min),alternative cooling-lubrication techniques have been developed on restriction of the coolants use.Among the several techniques,MQL(minimum quantity of lubricant)technique has received special attention from machining users because of its advantages in terms of surface quality of workpiece and drastic reduction in use of coolant.In this context,this paper evaluated the performance of the MQL technique as compared to the flood coolant in peripheral surface grinding of AISI P100(VP100)steel with conventional aluminum oxide grinding wheel in relation to the surface roughness(Ra and Rz).Input parameters tested were equivalent chip thickness(0.09μm,0.18μm and 0.27μm)and flow rate of the cutting fluid(60 mL/h,150 mL/h and 240 mL/h)of the MQL system.Results showed that the grinding with MQL technique provided lower surface roughness values compared to conventional flood cooling,especially when machining under the intermediary cutting conditions.Also,with exception of heq of 0.09 m,the MQL technique resulted in lower values of Rz parameter as compared to the conventional coolant technique,regardless of the flow rate tested.
基金supported by the National Key R&D Program of China(Grant No.2023YFC2413303)the National Natural Science Foundation of China(Grant No.52075128)the Natural Science Foundation of Heilongjiang Province,China(Grant No.YQ2020E013).
文摘Alumina dispersion-strengthened copper (ADSC), as a representative particle-reinforced metal matrix composite (PRMMC), exhibits superior wear resistance and high strength. However, challenges arise in their processability because of the non-uniform material properties of biphasic materials. In particular, limited research has been conducted on the reinforcement mechanism and behavior of particles during material cutting deformation of PRMMC with nanoscale particles. In this study, a cutting simulation model for ADSC was established, separating the nanoscale reinforcement particles from the matrix. This model was utilized to analyze the interactions among particles, matrix, and tool during the cutting process, providing insights into chip formation and fracture. Particles with high strength and hardness are more prone to storing stress concentrations, anchoring themselves at grain boundaries to resist grain fibration, thereby influencing the stress distribution in the cutting deformation zone. Stress concentration around the particles leads to the formation of discontinuous chips, indicating that ADSC with high-volume fractions of particle (VFP) exhibits low cutting continuity, which is consistent with the results of cutting experiments. The tool tip that is in contact with particles experiences stress concentration, thereby accelerating tool wear. Cutting ADSC with 1.1% VFP results in tool blunting, which increases the radius of cutting edge from 0.5 to 1.9 μm, accompanied with remarkable coating delamination and wear. Simulation results indicate that the minimum uncut chip thickness increases from 0.04 to 0.07 μm as VFP increases from 0.3% to 1.1%. In conjunction with scratch experiments, MUCT increases with the augmentation of VFP. Computational analysis of the specific cutting force indicates that particles contribute to the material’s size effect. The results of this study provide theoretical guidance for practical engineering machining of ADSC, indicating its great importance for the process design of components made from ADSC.
文摘Brittle materials have been widely employed for industrial applications due to their excellent mechanical, optical, physical and chemical properties. But obtaining smooth and damage-free surface on brittle materials by traditional machining methods like grinding, lapping and polishing is very costly and extremely time consuming. Ductile mode cutting is a very promising way to achieve high quality and crack-free surfaces of brittle materials. Thus the study of ductile mode cutting of brittle materials has been attracting more and more efforts. This paper provides an overview of ductile mode cutting of brittle materials including ductile nature and plasticity of brittle materials, cutting mechanism, cutting characteris- tics, molecular dynamic simulation, critical undeformed chip thickness, brittle-ductile transition, subsurface damage, as well as a detailed discussion of ductile mode cutting enhancement. It is believed that ductile mode cutting of brittle materials could be achieved when both crack-free and no subsurface damage are obtained simultaneously.
