The friction drive elevators the influence of the braking distance has very high significance to meet certain safety regulations and comfort.During the emergency braking the delay for the system a frame and a cabin sh...The friction drive elevators the influence of the braking distance has very high significance to meet certain safety regulations and comfort.During the emergency braking the delay for the system a frame and a cabin should be within the range from 0.2 to 9.81 m/s~2.However,there are no specialist literatures regarding the issues connected with emergency braking of elevating devices either.The results of the own empirical research work are presented regarding the influence of design changes on the working parameters of the friction drive elevator gears.ASG100,KB 160,PP16,PR2000UD and CHP2000 types of safety progressive gears are analyzed.ASG100,KB 160,PP16,PR2000UD type progressive gears are already produced by European manufacturers.CHP2000 type gears are established as the alternative option for the already existing solutions.The unique cam system has been used in the CHP 2000 gears.The cam leverage gives the chance to unblock,in a very easy way,the clamed gears after braking.Thus,it is a key aspect to perform laboratory tests over the braking process of a newly created solution.The proper value of the braking distance has a significant influence on the value of delay in terms of binding standards.The influence of loading on the effective braking distance and the value of the falling elevator cabin speed are analyzed and the results are presented.The results presented are interesting from lift devices operation and a new model of CHP 2000progressive gear point of view.展开更多
Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece (objective) and the other undeformable one (rigid). The microstructure evolut...Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece (objective) and the other undeformable one (rigid). The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.展开更多
The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable ...The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.展开更多
The flow field of the oil film between frictional pairs in the hydroviscous drive test rig is investigated. A three-dimensional Navier-Stokes(N-S) equation considering viscous force and inertial force rather than Re...The flow field of the oil film between frictional pairs in the hydroviscous drive test rig is investigated. A three-dimensional Navier-Stokes(N-S) equation considering viscous force and inertial force rather than Reynolds equation or modified Reynolds equation is presented to model the flow field. Pressure and temperature distribution in radial and circumferential direction under three different conditions, i.e., isothermal, that considering viscosity-temperature characteristic as well as shear thinning non-Newtonian fluid are simulated, respectively, by utilizing the commercial computational fluid dynamics(CFD) software FLUENT. The results reveal that the grooves on the driven plate make the pressure, temperature distribution present periodic variation. The oil temperature and shear rate have important effects on the flow field between frictional pairs, and the oil temperature is more important parameter. The simulation results lay a theoretical foundation for the reasonable designs ofhydroviscous drive.展开更多
On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are ...On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are investigated. The results of numerical simulation show that the temperature of friction surface is higher than that of other region and the peak temperature increases with the increase of welding time. During the process of friction stage, no flash appears because of the low temperature and the small axial friction pressure. At the forging stage, the flashes appear, whose dimensions and bending degree increase with the increase of welding temperature. Moreover, with the increase of rotational velocity and axial forging pressure, the dimensions and the bending degree of flashes of continuous drive friction welding increase.展开更多
The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque c...The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.展开更多
A friction model was established for impulse control design in a precision control system. First, the physical characteristics of the impulse in momentum, such as motion and energy, were analyzed and formulated. Then,...A friction model was established for impulse control design in a precision control system. First, the physical characteristics of the impulse in momentum, such as motion and energy, were analyzed and formulated. Then, experimental response to a new pulse with two harmonic expansions was studied. The first harmonic is the main pulse to drive the arm, and the second harmonic has two functions: its first half helps the main pulse eliminate the dead zone, and its second half, a negative pulse, stops the arm motion quickly. Finally, an impulse feedback controller was developed. Comparison between simulation and experiments shows the effectiveness of the proposed controller.展开更多
Continuous drive friction welding was employed to join the aeronautic aluminum alloy 2024.Parametric optimization and microstructural characterization were investigated.Results show that friction pressure is the most ...Continuous drive friction welding was employed to join the aeronautic aluminum alloy 2024.Parametric optimization and microstructural characterization were investigated.Results show that friction pressure is the most significant factor influencing the tensile strength of joints.To obtain a high joint efficiency,the combination of moderate friction pressure,less friction time and higher upset pressure is recommended.The optimized joint efficiency from Taguchi analysis reaches 92% of base metal.Under the optimized experimental condition,the interfacial peak temperature is calculated analytically in the range of 779-794 K,which is validated by experimental data.Fine recrystallized grains caused by the high temperature and plastic deformation are observed in the friction interface zone.The grain refinement is limited in the thermo-mechanically affected zone,where most of matrix grains are deformed severely.The extensive dissolution and limited re-precipitation of strengthening phases result in a lower microhardness in the friction interface zone than that in the thermo-mechanically affected zone.展开更多
基金Nova Trading Company from Torun and Rywal-RHC Company from Lublin for the financial support owing to which it was possible to perform the research study and tests presented in the compilation.
文摘The friction drive elevators the influence of the braking distance has very high significance to meet certain safety regulations and comfort.During the emergency braking the delay for the system a frame and a cabin should be within the range from 0.2 to 9.81 m/s~2.However,there are no specialist literatures regarding the issues connected with emergency braking of elevating devices either.The results of the own empirical research work are presented regarding the influence of design changes on the working parameters of the friction drive elevator gears.ASG100,KB 160,PP16,PR2000UD and CHP2000 types of safety progressive gears are analyzed.ASG100,KB 160,PP16,PR2000UD type progressive gears are already produced by European manufacturers.CHP2000 type gears are established as the alternative option for the already existing solutions.The unique cam system has been used in the CHP 2000 gears.The cam leverage gives the chance to unblock,in a very easy way,the clamed gears after braking.Thus,it is a key aspect to perform laboratory tests over the braking process of a newly created solution.The proper value of the braking distance has a significant influence on the value of delay in terms of binding standards.The influence of loading on the effective braking distance and the value of the falling elevator cabin speed are analyzed and the results are presented.The results presented are interesting from lift devices operation and a new model of CHP 2000progressive gear point of view.
文摘Macro-deformation characteristics of continuous drive friction welded mild steel joints were examined by using one deformable workpiece (objective) and the other undeformable one (rigid). The microstructure evolution and hardness change across the joint were studied. The results show that the axial shortening and radial increment of joints increase with increasing the frictiou time at l 200 rpm. The cementite particles of pearlites in the weld center are uniformly distributed on the ferrite matrix, while the cementites of the pearlite in the thermal-mechanically affected zone are broken and discontinuously dispersed in the pearlite. The hardness decreases rapidly from the weld center to the parent metal under the coupled effects of heat and deformation during the rapid heating and cooling processes.
文摘The aim of present study is introducing a method by subdividing friction welding phases into three steps according to the temperature change during continuous drive friction welding operation. Thermal curve allowable subdividing of the friction welding phase's time into three distinct periods, while the microstructure evolution during friction welding goes through three different situations. The effects of three distinct periods were achieved by macro-microscopy, microhardness HV_(0.1), tensile tests and scanning electronic microscopy(SEM).The results clearly show that the microstructure during the friction phase goes through three completely different situations which mechanically influenced on microstructure, tensile strength and ductility of the welded joint.
基金National Natural Science Foundation of China(No.50475106)
文摘The flow field of the oil film between frictional pairs in the hydroviscous drive test rig is investigated. A three-dimensional Navier-Stokes(N-S) equation considering viscous force and inertial force rather than Reynolds equation or modified Reynolds equation is presented to model the flow field. Pressure and temperature distribution in radial and circumferential direction under three different conditions, i.e., isothermal, that considering viscosity-temperature characteristic as well as shear thinning non-Newtonian fluid are simulated, respectively, by utilizing the commercial computational fluid dynamics(CFD) software FLUENT. The results reveal that the grooves on the driven plate make the pressure, temperature distribution present periodic variation. The oil temperature and shear rate have important effects on the flow field between frictional pairs, and the oil temperature is more important parameter. The simulation results lay a theoretical foundation for the reasonable designs ofhydroviscous drive.
基金Acknowledgement This work is supported by the National Natural Science Foundation of China (No. 51204111 ) and the Education Department Foun- dation of Liaoning Province (No. L2012047).
文摘On basis of the finite element software DEFORM, the 2D coupled thermo-mechanical model of continuous drive friction welding of ring parts is established. The temperature and the flashes during the welding process are investigated. The results of numerical simulation show that the temperature of friction surface is higher than that of other region and the peak temperature increases with the increase of welding time. During the process of friction stage, no flash appears because of the low temperature and the small axial friction pressure. At the forging stage, the flashes appear, whose dimensions and bending degree increase with the increase of welding temperature. Moreover, with the increase of rotational velocity and axial forging pressure, the dimensions and the bending degree of flashes of continuous drive friction welding increase.
基金Supported by National Natural Science Foundation of China(Grant Nos.51805351,U1810123)
文摘The hydro-viscous drive(HVD)has been widely used in fan transmission in vehicles,fans,and scraper conveyors for step-less speed regulation or soft starting.In the mixed friction stage,the contact,friction,and torque characteristics of friction pairs are very complex and change at any time.The characteristics of the frictional and hydrodynamic lubrication states were studied in order to calculate and predict the friction and torque characteristics of the friction pairs in the mixed friction stage.The fluid torque was calculated by applying the average shear stress model and the load-carrying capacity of asperity was determined on the basis of the fractal contact theory.In addition,the contact friction coefficient of the friction pairs was taken into consideration and measured by using the MM1000-Ⅲfriction and wear testing machine.The asperity friction torque and total torque in the mixed friction stage were obtained and finally,the test rig for the torque characteristics was set up.The results show that the contribution to the total torque is shared by the oil film and the asperity friction.The friction coefficient decreases sharply at first and then increases with a change in the relative rotational speed,following the Stribeck curve closely,and the contact frictional coefficient slowly decreases with increase in the pressure between the friction pairs.The torque between the friction pairs is provided by the asperity friction,and the torque due to the oil film reduces to zero.When the thickness of the oil film is small,a major contribution to the total torque is due to the asperity friction.The total torque also increases with the decrease in the film thickness ratio.Therefore,by theoretical analysis and experimental verification,the torque of the friction pairs in the mixed friction stage can be accurately calculated using the average shear stress model and asperity friction torque model.
基金The Foundation of Sichuan Education Department (No.09ZC24)
文摘A friction model was established for impulse control design in a precision control system. First, the physical characteristics of the impulse in momentum, such as motion and energy, were analyzed and formulated. Then, experimental response to a new pulse with two harmonic expansions was studied. The first harmonic is the main pulse to drive the arm, and the second harmonic has two functions: its first half helps the main pulse eliminate the dead zone, and its second half, a negative pulse, stops the arm motion quickly. Finally, an impulse feedback controller was developed. Comparison between simulation and experiments shows the effectiveness of the proposed controller.
基金Project(51475196) supported by the National Natural Science Foundation of ChinaProject(2017ZX04004001) supported by the National Science and Technology Major Project on High-end Numerically Controlled Machine Tools and Basic Manufacturing Technology,China
文摘Continuous drive friction welding was employed to join the aeronautic aluminum alloy 2024.Parametric optimization and microstructural characterization were investigated.Results show that friction pressure is the most significant factor influencing the tensile strength of joints.To obtain a high joint efficiency,the combination of moderate friction pressure,less friction time and higher upset pressure is recommended.The optimized joint efficiency from Taguchi analysis reaches 92% of base metal.Under the optimized experimental condition,the interfacial peak temperature is calculated analytically in the range of 779-794 K,which is validated by experimental data.Fine recrystallized grains caused by the high temperature and plastic deformation are observed in the friction interface zone.The grain refinement is limited in the thermo-mechanically affected zone,where most of matrix grains are deformed severely.The extensive dissolution and limited re-precipitation of strengthening phases result in a lower microhardness in the friction interface zone than that in the thermo-mechanically affected zone.