A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a no...A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a nominal component independent of the runout and a perturbation component induced by the runout. The instantaneous value of the nominal component is used to calibrate the cutting force coefficients. With the help of the perturbation component and the cutting force coefficients obtained above, the cutter runout is identified. Based on simulation and experimental results, the validity of the identification approach is demonstrated. The advantage of the proposed method lies in that the calibration performed with data of one cutting test under a specific regime can be applied for a great range of cutting conditions.展开更多
The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milli...The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process.展开更多
A roll-bending process that minimizes the flat areas on the leading and trailing ends of formed plates will produce more accurate and easier assemble final shapes. There are several methods of minimizing flat areas, b...A roll-bending process that minimizes the flat areas on the leading and trailing ends of formed plates will produce more accurate and easier assemble final shapes. There are several methods of minimizing flat areas, but they are costly or difficult to apply for thick plates. This study proposes a new, simple approach that reduces these flat areas. This approach includes moving the bottom roll slightly along the feeding direction and adjusting the bottom roll location. Sensitivity analyses were performed using a developed 3D dynamic FE （finite element） model of an asymmetrical roll-bending process in the Ansys/LS-Dyna software package. Simulations were validated by experiments run on an instrumented roll-bending machine. The FE results indicate that this new approach not only minimizes the flat areas but also reduces the forming forces.展开更多
In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. Th...In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. The mediums without aging treatment, which are prepared by using a prepolymer process and have diamond-machined end faces to produce the required optical finish, give a highest laser output of 281.9 mJ with 0.215% slope efficiency at 2.0x 10^-4 mol/L. The best medium lifetime is 21 shots to 50% of original output equating 74.6 k J/liter.展开更多
Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consis...Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consistent mechanical parameters due to substantial variations in rock properties.In this research,uniaxial compression tests on dolerite specimens collected from a gold mine in Western Australia showed substantial scatter in the results.Rock categorization based on the P-wave velocities is as accurate as the thin section analysis,which suggests that they can be used together to gain a more accurate initial understanding of the rock types before any laboratory testing.The quality of specimen preparation and rockemachine interaction greatly affect the test results.For instance,non-parallelness of loading platens can lead to considerable scatter of the testing results,which would be perceived as rock variability.It is suggested that the current testing standards should be modified towards a better control of the loading machine performance and equipment precision.Finally,the possibility of pre-existing microcracks in rock,neither detected by the thin section analysis nor by the ultrasonic measurement,must be examined by computed tomography(CT)scanning as they can affect the test results.This study will enhance our knowledge about the sources of variability in laboratory test results of rock which is essential for obtaining reliable data.展开更多
基金National Natural Science Foundation of China (50435020) Natural Science Foundation of Shaanxi Province(2004E217)+1 种基金the Doctorate Creation Foundation of Northwestern Polytechnical Uni-versity (CX200411)Youth for NPU Teachers Scientific and Technologi-cal Innovation Foundation
文摘A new mechanistic cutting force model for flat end milling using the instantaneous cutting force coefficients is proposed. An in-depth analysis shows that the total cutting forces can be separated into two terms: a nominal component independent of the runout and a perturbation component induced by the runout. The instantaneous value of the nominal component is used to calibrate the cutting force coefficients. With the help of the perturbation component and the cutting force coefficients obtained above, the cutter runout is identified. Based on simulation and experimental results, the validity of the identification approach is demonstrated. The advantage of the proposed method lies in that the calibration performed with data of one cutting test under a specific regime can be applied for a great range of cutting conditions.
基金supported by National Natural Science Foundation of China (Grant No. 51075054)National Basic Research Program of China (973 Program, Grant No. 2005CB724100)Program for New Century Excellent Talents in University of China (Grant No. NCET-08-081)
文摘The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process.
文摘A roll-bending process that minimizes the flat areas on the leading and trailing ends of formed plates will produce more accurate and easier assemble final shapes. There are several methods of minimizing flat areas, but they are costly or difficult to apply for thick plates. This study proposes a new, simple approach that reduces these flat areas. This approach includes moving the bottom roll slightly along the feeding direction and adjusting the bottom roll location. Sensitivity analyses were performed using a developed 3D dynamic FE （finite element） model of an asymmetrical roll-bending process in the Ansys/LS-Dyna software package. Simulations were validated by experiments run on an instrumented roll-bending machine. The FE results indicate that this new approach not only minimizes the flat areas but also reduces the forming forces.
文摘In order to obtain a high output energy from a xenon lamp-pumped solid-state dye laser, homogeneities of laser mediums and flatnesses of medium faces with different processing treatments are discussed in the paper. The mediums without aging treatment, which are prepared by using a prepolymer process and have diamond-machined end faces to produce the required optical finish, give a highest laser output of 281.9 mJ with 0.215% slope efficiency at 2.0x 10^-4 mol/L. The best medium lifetime is 21 shots to 50% of original output equating 74.6 k J/liter.
基金the Curtin Strategic International Research Scholarship(CSIRS)and Mining Research Institute of Western Australia(MRIWA)-project M474 scholarshipthe Australian Research Council through project DP190103260.
文摘Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consistent mechanical parameters due to substantial variations in rock properties.In this research,uniaxial compression tests on dolerite specimens collected from a gold mine in Western Australia showed substantial scatter in the results.Rock categorization based on the P-wave velocities is as accurate as the thin section analysis,which suggests that they can be used together to gain a more accurate initial understanding of the rock types before any laboratory testing.The quality of specimen preparation and rockemachine interaction greatly affect the test results.For instance,non-parallelness of loading platens can lead to considerable scatter of the testing results,which would be perceived as rock variability.It is suggested that the current testing standards should be modified towards a better control of the loading machine performance and equipment precision.Finally,the possibility of pre-existing microcracks in rock,neither detected by the thin section analysis nor by the ultrasonic measurement,must be examined by computed tomography(CT)scanning as they can affect the test results.This study will enhance our knowledge about the sources of variability in laboratory test results of rock which is essential for obtaining reliable data.
