The current research on noncircular hobbing mainly focuses on the linkage model and motion realization.However,the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing proc...The current research on noncircular hobbing mainly focuses on the linkage model and motion realization.However,the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing process.In this paper,a hobbing machining model with tool-shifting characteristics was proposed to solve the problems of cutting force fluctuation and inconsistency of tooth profile envelope accuracy at different positions of the pitch curve in noncircular gear hobbing.Based on the unit cutting force coefficient method,the undeformed chip volume generated by interrupted cutting was used to characterize the fluctuation trend of the hobbing force.The fluctuation characteristics of the cutting force generated by different hobbing models were compared and analyzed.Using the equivalent gear tooth and hob slotting numbers,an analysis model of the tooth profile envelope error of the noncircular gear was constructed.Subsequently,the tooth profile envelope errors at different positions of the pitch curve were compared and analyzed based on the constructed model.The transmission structure of the electronic gearbox was constructed based on the proposed hobbing model,and the hobbing experiment was conducted based on the selfdeveloped noncircular gear CNC hobbing system.This paper proposes a hobbing method that can effectively suppress the fluctuation of the peak and whole circumference cutting force and reduce the maximum envelope error of the whole circumference gear teeth.展开更多
Nanolubricant mixing the normal lubricant with nanoparticles, gradually becomes a new trend study for metal cutting enhancement. An addition of the nanoparticles improves lubricating properties and convective heat tra...Nanolubricant mixing the normal lubricant with nanoparticles, gradually becomes a new trend study for metal cutting enhancement. An addition of the nanoparticles improves lubricating properties and convective heat transfer coefficient (cooling properties) of nanolubricants. In the present work, nanolubricant is formulated by using dispersions of 0.3% Al2O3 nanoparticles in normal industrial oil VG46 for enhancement of gear machining performance of SCM420 steel. Comparative study of flank wear, crater wear and gear profile error in gear hobbing with normal oils in the existing production line as well as nanolubricant is studied. This study clearly reveals that tool wear, and gear profile error are reduced by the use of nanolubricant compared to that of normal oils. The paper results not only contribute the deeper understanding of the novel performance of nanoparticles in conventional cutting fluids, but also show a very promising solution to achieve the engineering economy effectiveness in gear machining.展开更多
In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and ...In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and the law of water demand of P.szechuanica was grasped.In this paper,potted seedlings of 1-0 rooted cuttings of P.szechuanica were taken as research objects,and change situation of water consumption under different water control gradients was measured regularly by using weighing method,further analyzing dynamic change of water consumption of P.szechuanica and revealing water demand law of 1-0 rooted cuttings of P.szechuanica.The results showed that total change of water consumption of 1-0 rooted cuttings of P.szechuanica had"slow-fast-slow-fast"double-peak trend in the growth period of the current year,and corresponded with univariate linear relation(R^(2)=0.7137),with significant difference.In whole growth period,water consumption in August was the highest,which was 2.7 times of that in June and July and 1.5 times of that after September.In different water control treatments,the dynamic changes of daily and monthly water consumption were significantly different.In seven water control treatments,monthly water consumption was between(6315.95±1690.70)and(10105.28±3065.30)g/month,and mean was(8211.07±2308.23)g/month.With intensification of water control treatment,water consumption increased,but there was no seedling death due to water shortage.P.szechuanica has great plasticity in water demand,and can survive in both arid and humid environments.Meanwhile,it is revealed that P.szechuanica is the most widely distributed tree species in the region.展开更多
For helping find out the cause of the extrusion wound of gear and the abnormal abrasion wear in the process of gear shaping, this disquisition studies the varying law of the cut-thickness of chips in gear shaping and ...For helping find out the cause of the extrusion wound of gear and the abnormal abrasion wear in the process of gear shaping, this disquisition studies the varying law of the cut-thickness of chips in gear shaping and deduces a set of formulas for it.展开更多
According to work tool thermocouple principle,the equipment for measuring hobbing temperature is developed.The changing character of cutting temperature in gear hobbing,the relation between cutting conditions and hob...According to work tool thermocouple principle,the equipment for measuring hobbing temperature is developed.The changing character of cutting temperature in gear hobbing,the relation between cutting conditions and hobbing temperature,and the influence of cutting conditions on hobbing temperature are discussed by means of experiments.All these have provided the reference standards for the equitably selecting cutting conditions and geometrical parameter of hob,prolonging the life of gear hobs,and predicting processes of gear hobbing.展开更多
Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to impro...Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.52075142 and U22B2084).
文摘The current research on noncircular hobbing mainly focuses on the linkage model and motion realization.However,the intermittent cutting characteristics of hobbing would increase uncertainties in the manufacturing process.In this paper,a hobbing machining model with tool-shifting characteristics was proposed to solve the problems of cutting force fluctuation and inconsistency of tooth profile envelope accuracy at different positions of the pitch curve in noncircular gear hobbing.Based on the unit cutting force coefficient method,the undeformed chip volume generated by interrupted cutting was used to characterize the fluctuation trend of the hobbing force.The fluctuation characteristics of the cutting force generated by different hobbing models were compared and analyzed.Using the equivalent gear tooth and hob slotting numbers,an analysis model of the tooth profile envelope error of the noncircular gear was constructed.Subsequently,the tooth profile envelope errors at different positions of the pitch curve were compared and analyzed based on the constructed model.The transmission structure of the electronic gearbox was constructed based on the proposed hobbing model,and the hobbing experiment was conducted based on the selfdeveloped noncircular gear CNC hobbing system.This paper proposes a hobbing method that can effectively suppress the fluctuation of the peak and whole circumference cutting force and reduce the maximum envelope error of the whole circumference gear teeth.
文摘Nanolubricant mixing the normal lubricant with nanoparticles, gradually becomes a new trend study for metal cutting enhancement. An addition of the nanoparticles improves lubricating properties and convective heat transfer coefficient (cooling properties) of nanolubricants. In the present work, nanolubricant is formulated by using dispersions of 0.3% Al2O3 nanoparticles in normal industrial oil VG46 for enhancement of gear machining performance of SCM420 steel. Comparative study of flank wear, crater wear and gear profile error in gear hobbing with normal oils in the existing production line as well as nanolubricant is studied. This study clearly reveals that tool wear, and gear profile error are reduced by the use of nanolubricant compared to that of normal oils. The paper results not only contribute the deeper understanding of the novel performance of nanoparticles in conventional cutting fluids, but also show a very promising solution to achieve the engineering economy effectiveness in gear machining.
基金Supported by Natural Science Foundation of Tibet Autonomous Region(XZ2019ZRG-58)Forestry Discipline Innovation Team Construction Project of Tibet Agriculture&Animal Husbandry University(Tibet Financial Forecast:2020-001).
文摘In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and the law of water demand of P.szechuanica was grasped.In this paper,potted seedlings of 1-0 rooted cuttings of P.szechuanica were taken as research objects,and change situation of water consumption under different water control gradients was measured regularly by using weighing method,further analyzing dynamic change of water consumption of P.szechuanica and revealing water demand law of 1-0 rooted cuttings of P.szechuanica.The results showed that total change of water consumption of 1-0 rooted cuttings of P.szechuanica had"slow-fast-slow-fast"double-peak trend in the growth period of the current year,and corresponded with univariate linear relation(R^(2)=0.7137),with significant difference.In whole growth period,water consumption in August was the highest,which was 2.7 times of that in June and July and 1.5 times of that after September.In different water control treatments,the dynamic changes of daily and monthly water consumption were significantly different.In seven water control treatments,monthly water consumption was between(6315.95±1690.70)and(10105.28±3065.30)g/month,and mean was(8211.07±2308.23)g/month.With intensification of water control treatment,water consumption increased,but there was no seedling death due to water shortage.P.szechuanica has great plasticity in water demand,and can survive in both arid and humid environments.Meanwhile,it is revealed that P.szechuanica is the most widely distributed tree species in the region.
文摘For helping find out the cause of the extrusion wound of gear and the abnormal abrasion wear in the process of gear shaping, this disquisition studies the varying law of the cut-thickness of chips in gear shaping and deduces a set of formulas for it.
文摘According to work tool thermocouple principle,the equipment for measuring hobbing temperature is developed.The changing character of cutting temperature in gear hobbing,the relation between cutting conditions and hobbing temperature,and the influence of cutting conditions on hobbing temperature are discussed by means of experiments.All these have provided the reference standards for the equitably selecting cutting conditions and geometrical parameter of hob,prolonging the life of gear hobs,and predicting processes of gear hobbing.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University(IRT1294)the China National Science and Technology Major Projects(Grant No:2016ZX05011)
文摘Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.