A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p ...A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p erature, tool life and cutting temperature were investigated and compared. The m aterial can be heated by this instrument which using low voltage and high elec trical current, while PCBN can’t be heated by electrifying directly, so the ke ntanium layer coating over the PCBN is heated, so the PCBN is heated and its th ermoelectric property is got by this method. [TPP129,+60mm88mm,Y,PZ#] Fig.1 Effect of cutting depth and workpiec hardness on. the cutting temperatureThe objective was to determine the influence of the workpiece hardness on change s in cutting temperature and tool wear characterize. It can be found from Fig.1 that the cutting temperature show an increasing tendency with the improvement of workpiece hardness within the cutting speed scope when the workpiece hardness i s under HRC50. And on the other hand, it is found that the cutting temperature s how the downtrend with the improvement of workpiece hardness when the workpiece hardness is over HRC50. According to experimental results, the critical hard ness when turning hardened GCr15 bearing steel with PCBN tool is about HRC50. Th e wear causes of PCBN tool have been found out through taking photos on the micr o-shape of PCBN poly-laminate initial surface as well as face and flank of wea r tool and analysis on chemical elements. It is discovered that the PCBN tools a re not suitable for cutting the workpiece at nearly critical hardness, because n ear the critical hardness, PCBN wear at the highest speed. For researching the w ear rule of PCBN tool, the tool wear experiments have been carried on by using b earing steel GCr15 at hardness HRC40 and HRC60 with changing cutting speed. The indexes of tool life equations is gained under two kinds of conditions w hich are bigger than 0.6, so the effects of cutting speed on the PCBN tool are m uch less than that of carbide tool and ceramic tool.展开更多
Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received ...Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via intemet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.展开更多
Many researches show that, in metal cutting process, tool wear rate depends on some cutting process parameters, such as temperature at tool face, contact pressure and relative sliding velocity at tool/chip and tool/wo...Many researches show that, in metal cutting process, tool wear rate depends on some cutting process parameters, such as temperature at tool face, contact pressure and relative sliding velocity at tool/chip and tool/workpiece interfaces. Finite element method(FEM) application enables the estimate of these parameters and the tool wear. A tool wear estimate program based on chip formation and heat transfer analysis is designed and compiled with Python to calculate the wear rate and volume, and update tool geometry according to the tool wear. The progressive flank and crater wears in milling operation are estimated by the program. The FEM code ABAQUS/Explicit and Standard are employed to analyze chip formation and heat transfer process.展开更多
High speed machining has received an important interest because it leads to an increase of productivity and a better workpiece surface quality. However, at high cutting speeds, the tool wear increases dramatically due...High speed machining has received an important interest because it leads to an increase of productivity and a better workpiece surface quality. However, at high cutting speeds, the tool wear increases dramatically due to the high temperature at the tool-workpiece interface. Tool wear impairs the surface finish and hence the tool life is reduced. That is why an important objective of metal cutting research has been the assessment of tool wear patterns and mechanisms. In this paper, wear performances of PCBN tool, ceramic tool, coated carbide tool and fine-grained carbide tool in high speed face milling were presented when cutting cast iron, 45# tempered carbon steel and 45# hardened carbon steel. Tool wear patterns were examined through a tool-making microscope. The research results showed that tool wear types differed in various matching of materials between cutting tool and workpiece. The dominant wear patterns observed were rake face wear, flank wear, chipping, fracture and breakage. The main wear mechanisms were mechanical friction, adhesion, diffusion and chemical wear promoted by cutting forces and high cutting temperature. Hence, the important considerations of high speed cutting tool materials are high heat-resistance and wear-resistance, chemical stability as well as resistance to failure of coatings. The research results will be great benefit to the design and the selection of tool materials and control of tool wear in high-speed machining processes.展开更多
Inconel 718, a high temperature alloy, is extensive ly used in aircraft, gas engines and nuclear-power plants. It is generally known that the life of ceramic cutting tools in machining Inconel 718 is often restric ted...Inconel 718, a high temperature alloy, is extensive ly used in aircraft, gas engines and nuclear-power plants. It is generally known that the life of ceramic cutting tools in machining Inconel 718 is often restric ted by depth-of-cut (DOC) notch wear. In view of the number of various factors involved and the variety of tool materi als and cutting conditions available, the analysis of the DOC notch wear is very difficult. According to previous work concerning the DOC notch wear of ceramics tools, some Al 2O 3 - and Si 3N 4 -based ceramics tools have show n that the degree of tool notching depends on the thermal shock resistance of a tool material and thermal gradients (interrupted cutting, use of flood coolants) . Other observations suggest that there are chemical interactions between the to ol material and the work-piece. At the same time, an analytical technique based on thermodynamic properties for estimating cutting tool wear was proposed. Howe ver, so far, there is no concrete and convincing explanation for the DOC notch w ear. In all previous studies on the DOC notch wear, it is often assumed that notch we ar happened in the contacting region of the cutting tool and the work-piece, wh ile the exact position of notch wear is always neglected. In his article, He Ning measured the distance l n between tool nose and the center of DOC notch wear, and calculated the theoretical working length l d ― the ideal distance between the DOC notch center and the intersection of th e theoretical depth of cut line and the cutting edge. He found that l n is always greater than l d. It means that the position of the DOC notch is not at the depth of cut line, but out of the theoretical cutting area. He supposed that the saw-tooth shaped burrs and fin-shaped chip edges cause the DOC no tch wear, because only the saw-tooth shaped burrs and fin-shaped chip edges ha ve effect on the tools at the region of notch wear. Although He described the reason of notch wear and did some theoretical analysis of it, he has not done some experiments to verify it. In this paper, an experim ent was done to verify He’s assumption about DOC notch wear. In the present exp eriment, which has been done with the ceramic inserts (LT55), Working conditions at the region of DOC notch wear were analyzed. By using a KISTLER 9265B dyn amometer, the dynamic cutting force signals in three directions were pick up. By comparison between the theoretical frequency, with which the saw-shaped burr a nd fin-shaped chip edge impact on the region of notch wear, and the experimenta l results, it can be seen that the high frequency components of dynamic cutting forces mainly result from the impact effects of the saw-shaped burr and fin-sh aped chip edge. In high speed machining of nickel based alloys, DOC notch wear of ceramic tools is mainly because the impact effect of the burr and fin-shaped chip edge causes tools to be of fatigue damage, and the adherence between tool material and work piece material changes the direction of pressure stress and makes the micro-cra ck to appear and extend quickly.展开更多
The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cu...The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.展开更多
Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytica...Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytical force model to indicate the effect of coating material, cutting speed, feed rate on tool life and surface roughness was conducted experimentally. Cutting tests were performed using round inserts, with cutting speeds ranging from 50 to 300 rn/min, and feed rates from 0.1 to 0.4 mm/tooth, without using cooling liquids. The behavior of the TiN and TiCN layers using various cutting conditions was analyzed with orthogonal machining force model. Cutting results indicate that different coated tools, together with cutting variables, play a significant role in determining the machinability when milling Mar-M247.展开更多
文摘A study was undertaken to investigate the performan ce of PCBN tool in the finish turning GCr15 bearing steel with different hardness between 30～64 HRC. The natural thermocouple was used to measure the cutting tem p erature, tool life and cutting temperature were investigated and compared. The m aterial can be heated by this instrument which using low voltage and high elec trical current, while PCBN can’t be heated by electrifying directly, so the ke ntanium layer coating over the PCBN is heated, so the PCBN is heated and its th ermoelectric property is got by this method. [TPP129,+60mm88mm,Y,PZ#] Fig.1 Effect of cutting depth and workpiec hardness on. the cutting temperatureThe objective was to determine the influence of the workpiece hardness on change s in cutting temperature and tool wear characterize. It can be found from Fig.1 that the cutting temperature show an increasing tendency with the improvement of workpiece hardness within the cutting speed scope when the workpiece hardness i s under HRC50. And on the other hand, it is found that the cutting temperature s how the downtrend with the improvement of workpiece hardness when the workpiece hardness is over HRC50. According to experimental results, the critical hard ness when turning hardened GCr15 bearing steel with PCBN tool is about HRC50. Th e wear causes of PCBN tool have been found out through taking photos on the micr o-shape of PCBN poly-laminate initial surface as well as face and flank of wea r tool and analysis on chemical elements. It is discovered that the PCBN tools a re not suitable for cutting the workpiece at nearly critical hardness, because n ear the critical hardness, PCBN wear at the highest speed. For researching the w ear rule of PCBN tool, the tool wear experiments have been carried on by using b earing steel GCr15 at hardness HRC40 and HRC60 with changing cutting speed. The indexes of tool life equations is gained under two kinds of conditions w hich are bigger than 0.6, so the effects of cutting speed on the PCBN tool are m uch less than that of carbide tool and ceramic tool.
基金supported by Changwon National University in 2009-2010
文摘Remote monitoring of tools for prediction of tool wear in cutting processes was considered, and a method of implementation of a remote-monitoring system previously developed was proposed. Sensor signals were received and tool wear was predicted in the local system using an ART2 algorithm, while the monitoring result was transferred to the remote system via intemet. The monitoring system was installed at an on-site machine tool for monitoring three kinds of tools cutting titanium alloys, and the tool wear was evaluated on the basis of vigilances, similarities between vibration signals received and the normal patterns previously trained. A number of experiments were carried out to evaluate the performance of the proposed system, and the results show that the wears of finishing-cut tools are successfully detected when the moving average vigilance becomes lower than the critical vigilance, thus the appropriate tool replacement time is notified before the breakage.
基金Sponsored by National Natural Science Foundation of China(NSFC50505003)Excellent Young Scholars Research Foundation of Beijing Institute of Technology(000Y03-14)
文摘Many researches show that, in metal cutting process, tool wear rate depends on some cutting process parameters, such as temperature at tool face, contact pressure and relative sliding velocity at tool/chip and tool/workpiece interfaces. Finite element method(FEM) application enables the estimate of these parameters and the tool wear. A tool wear estimate program based on chip formation and heat transfer analysis is designed and compiled with Python to calculate the wear rate and volume, and update tool geometry according to the tool wear. The progressive flank and crater wears in milling operation are estimated by the program. The FEM code ABAQUS/Explicit and Standard are employed to analyze chip formation and heat transfer process.
文摘High speed machining has received an important interest because it leads to an increase of productivity and a better workpiece surface quality. However, at high cutting speeds, the tool wear increases dramatically due to the high temperature at the tool-workpiece interface. Tool wear impairs the surface finish and hence the tool life is reduced. That is why an important objective of metal cutting research has been the assessment of tool wear patterns and mechanisms. In this paper, wear performances of PCBN tool, ceramic tool, coated carbide tool and fine-grained carbide tool in high speed face milling were presented when cutting cast iron, 45# tempered carbon steel and 45# hardened carbon steel. Tool wear patterns were examined through a tool-making microscope. The research results showed that tool wear types differed in various matching of materials between cutting tool and workpiece. The dominant wear patterns observed were rake face wear, flank wear, chipping, fracture and breakage. The main wear mechanisms were mechanical friction, adhesion, diffusion and chemical wear promoted by cutting forces and high cutting temperature. Hence, the important considerations of high speed cutting tool materials are high heat-resistance and wear-resistance, chemical stability as well as resistance to failure of coatings. The research results will be great benefit to the design and the selection of tool materials and control of tool wear in high-speed machining processes.
文摘Inconel 718, a high temperature alloy, is extensive ly used in aircraft, gas engines and nuclear-power plants. It is generally known that the life of ceramic cutting tools in machining Inconel 718 is often restric ted by depth-of-cut (DOC) notch wear. In view of the number of various factors involved and the variety of tool materi als and cutting conditions available, the analysis of the DOC notch wear is very difficult. According to previous work concerning the DOC notch wear of ceramics tools, some Al 2O 3 - and Si 3N 4 -based ceramics tools have show n that the degree of tool notching depends on the thermal shock resistance of a tool material and thermal gradients (interrupted cutting, use of flood coolants) . Other observations suggest that there are chemical interactions between the to ol material and the work-piece. At the same time, an analytical technique based on thermodynamic properties for estimating cutting tool wear was proposed. Howe ver, so far, there is no concrete and convincing explanation for the DOC notch w ear. In all previous studies on the DOC notch wear, it is often assumed that notch we ar happened in the contacting region of the cutting tool and the work-piece, wh ile the exact position of notch wear is always neglected. In his article, He Ning measured the distance l n between tool nose and the center of DOC notch wear, and calculated the theoretical working length l d ― the ideal distance between the DOC notch center and the intersection of th e theoretical depth of cut line and the cutting edge. He found that l n is always greater than l d. It means that the position of the DOC notch is not at the depth of cut line, but out of the theoretical cutting area. He supposed that the saw-tooth shaped burrs and fin-shaped chip edges cause the DOC no tch wear, because only the saw-tooth shaped burrs and fin-shaped chip edges ha ve effect on the tools at the region of notch wear. Although He described the reason of notch wear and did some theoretical analysis of it, he has not done some experiments to verify it. In this paper, an experim ent was done to verify He’s assumption about DOC notch wear. In the present exp eriment, which has been done with the ceramic inserts (LT55), Working conditions at the region of DOC notch wear were analyzed. By using a KISTLER 9265B dyn amometer, the dynamic cutting force signals in three directions were pick up. By comparison between the theoretical frequency, with which the saw-shaped burr a nd fin-shaped chip edge impact on the region of notch wear, and the experimenta l results, it can be seen that the high frequency components of dynamic cutting forces mainly result from the impact effects of the saw-shaped burr and fin-sh aped chip edge. In high speed machining of nickel based alloys, DOC notch wear of ceramic tools is mainly because the impact effect of the burr and fin-shaped chip edge causes tools to be of fatigue damage, and the adherence between tool material and work piece material changes the direction of pressure stress and makes the micro-cra ck to appear and extend quickly.
基金Project(51175122)supported by the National Natural Science Foundation of China
文摘The aim of this work is to simulate thermal deformation of tool system and investigate the influence of cutting parameters on it in single-point diamond turning(SPDT) of aluminum alloy. The experiments with various cutting parameters were conducted. Cutting temperature was measured by FLIR A315 infrared thermal imager. Tool wear was measured by scanning electron microscope(SEM). The numerical model of heat flux considering tool wear generated in cutting zone was established. Then two-step finite element method(FEM) simulations matching the experimental conditions were carried out to simulate the thermal deformation. In addition, the tests of deformation of tool system were performed to verify previous simulation results. And then the influence of cutting parameters on thermal deformation was investigated. The results show that the temperature and thermal deformation from simulations agree well with the results from experiments in the same conditions. The maximum thermal deformation of tool reaches to 7 μm. The average flank wear width and cutting speed are the dominant factors affecting thermal deformation, and the effective way to decrease the thermal deformation of tool is to control the tool wear and the cutting speed.
文摘Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytical force model to indicate the effect of coating material, cutting speed, feed rate on tool life and surface roughness was conducted experimentally. Cutting tests were performed using round inserts, with cutting speeds ranging from 50 to 300 rn/min, and feed rates from 0.1 to 0.4 mm/tooth, without using cooling liquids. The behavior of the TiN and TiCN layers using various cutting conditions was analyzed with orthogonal machining force model. Cutting results indicate that different coated tools, together with cutting variables, play a significant role in determining the machinability when milling Mar-M247.
