scholarly journals Impact System Dynamic Characteristics of Hydraulic Rock Drill Based on an Overlapped Reversing Valve

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yelin Li ◽  
Youxin Luo ◽  
Xiao Wu
Keyword(s):  
Dynamic Characteristics ◽  
Equilibrium Position ◽  
Pressure Pulsation ◽  
System Dynamic ◽  
Characteristic Curves ◽  
Pressure Characteristic ◽  
Impact System ◽  
Rock Drill ◽  
Newton’S Laws ◽  
The Impact

For the phenomenon of a hydraulic rock drill based on an underlapped reversing valve, the mechanical structure of the overlapped reversing form was proposed, which affected the pressure pulsation of the impact system, and motion of the impact piston was analyzed. The model of a hydraulic rock drill was built based on Newton’s laws. The initial lead size of the reversing point was calculated by the equilibrium position of the damping piston and final velocity of the impact piston. The size of the overlapped reversing valve was designed and the best impact interval was calculated, according to pressure characteristic curves in the piston of the front-rear chamber and in the reversing valve of the left-right chamber, and the damping piston floating feature had an impact on initial lead size of the reversing point. The advantages of the overlapped reversing valve were analyzed, by contrasting the pressure pulsation of the impact system and motion of the impact piston with the underlapped reversing valve. The inner mechanism experiment of the hydraulic rock drill was designed to test the pressure characteristic curves in the piston of the front-rear chamber and in the reversing valve of the left-right chamber. The model of the overlapped reversing valve was verified by the experiment.

Response Analysis of van der Pol Vibro-Impact System with Coulomb Friction Under Gaussian White Noise

2018 ◽  
Vol 28 (13) ◽  
pp. 1830043 ◽  
Author(s):  
Meng Su ◽  
Wei Xu ◽  
Guidong Yang
Keyword(s):  
White Noise ◽  
Coulomb Friction ◽  
Gaussian White Noise ◽  
Original System ◽  
Stochastic Averaging ◽  
Response Analysis ◽  
State Variables ◽  
Van Der Pol ◽  
Impact System ◽  
The Impact

In this paper, the stationary response of a van der Pol vibro-impact system with Coulomb friction excited by Gaussian white noise is studied. The Zhuravlev nonsmooth transformation of the state variables is utilized to transform the original system to a new system without the impact term. Then, the stochastic averaging method is applied to the equivalent system to obtain the stationary probability density functions (pdfs). The accuracy of the analytical results obtained from the proposed procedure is verified by those from the Monte Carlo simulation based on the original system. Effects of different damping coefficients, restitution coefficients, amplitudes of friction and noise intensities on the response are discussed. Additionally, stochastic P-bifurcations are explored.

Study on Dynamic Characteristics of Hydraulic Pressure System of MPM Tube Rolling Mill

2013 ◽  
Vol 706-708 ◽  
pp. 1580-1584
Author(s):  
Gui Hua Fang ◽  
Jian Bo Wang ◽  
Wen Shuai Zheng
Keyword(s):  
Dynamic Characteristics ◽  
Response Speed ◽  
Pipe Production ◽  
Hydraulic Pressure ◽  
Hydraulic Control ◽  
Pressure System ◽  
Steel Rolling ◽  
Hydraulic Servo ◽  
Tube Rolling Mill ◽  
The Impact

Now MPM mill is widely used in hydraulic servo control technology in the field of seamless steel pipe production. But the hydraulic control system has the defect of complex control, bigger load power, more disturbance factors, higher response speed requirement and so on, which are unfavorable for analyzing the impact of factors of steel rolling precision. The conclusions show that: the system model is conducive to the analysis of the factors that affect the rolling accuracy, and it provides a theoretical basis for study the dynamic characteristics of the system, the optimal design and so on.

scholarly journals Influence of the Lubrication Oil Temperature on the Disengaging Dynamic Characteristics of a Cu-Based Wet Multi-Disc Clutch

2021 ◽  
Vol 11 (23) ◽  
pp. 11299
Author(s):  
Liangjie Zheng ◽  
Biao Ma ◽  
Man Chen ◽  
Liang Yu ◽  
Qian Wang
Keyword(s):  
Dynamic Characteristics ◽  
Hydrodynamic Lubrication ◽  
Friction Pair ◽  
Automatic Transmission ◽  
Friction Torque ◽  
Asperity Contact ◽  
Uniformity Coefficient ◽  
Lubrication Oil ◽  
The Impact ◽  
First Time

Clutch disengaging dynamic characteristics, including the disengaging duration and the variations of friction pair gaps and friction torque, are crucial to the shifting control of an automatic transmission. In the present paper, the influence of lubrication oil (ATF) temperature on disengaging dynamic characteristics is investigated through a comprehensive numerical model for the clutch disengaging process, which considers the hydrodynamic lubrication, the asperity contact, the heat transfer, the spline resistance, and the impact between the piston and clutch hub. Moreover, the non-uniformity coefficient (NUC) is proposed to characterize the disengaging uniformity of friction pairs. As the ATF temperature increases from 60 °C to 140 °C, the clutch disengaging duration shortens remarkably (shortened by 55.1%); besides, the NUC sees a decreasing trend before a slight increase. When the ATF temperature is 80 °C, the distribution of friction pair gaps is most uniform. During the disengaging process, the increase of ATF temperature not only accelerates the change of the lubrication status between friction pairs but also contributes to the decrease of contact torque and hydrodynamic torque. This research demonstrates for the first time, evidence for clutch disengaging dynamic characteristics with the consideration of ATF temperature.

scholarly journals Analysis and Experimental Investigation of Vibration Characteristics of Rotary Platform of Hydraulic Excavator under Complex Working Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Tinghao Li ◽  
Fuxiu Liu ◽  
Zhaojun Li ◽  
Mingjin Lu ◽  
Qiulu He
Keyword(s):  
Working Conditions ◽  
Dynamic Characteristics ◽  
Pressure Pulsation ◽  
Vibration Characteristics ◽  
Hydraulic Excavator ◽  
Rotary Platform ◽  
Road Excitation ◽  
Engine Excitation ◽  
Internal Relationships ◽  
Excitation Pressure

The rotary platform is the load-bearing substrate of a hydraulic excavator. The dynamic characteristics of the rotary platform directly affect the reliability and safety of the whole machine of a hydraulic excavator. In this work, the characteristics of the main external excitations acting on the hydraulic excavator such as the engine excitation, pressure pulsation excitation of the piston pump, inertial excitation of the working device, and road excitation are analyzed. The vibration transmission paths under the action of external excitations are ascertained. A vibration test method for the rotary platform of the hydraulic excavator is proposed. The vibration characteristics of the rotary platform under complex working conditions are researched, and the internal relationships between the vibration characteristics of the rotary platform and the engine excitation, pressure pulsation excitation of the piston pump, and road excitation are analyzed experimentally. The results show that the rotary platform is subjected to different excitations when it is under different working conditions. Moreover, the internal relationships between the dynamic characteristics of the rotary platform and the external excitation characteristics can be discovered by analyzing the vibration signals of the rotary platform, and the dynamic characteristics of the whole machine of the hydraulic excavator can be deeply studied based on the vibration characteristics of the rotary platform.

scholarly journals The theoretical approaches for calculation of the vertical effective pressure of drop impact of artificial rain on soil and hard surface

2016 ◽  
Vol 1 ◽  
pp. 16-20
Author(s):  
Bryl S.V. ◽  
Zverkov M.S.
Keyword(s):  
Solid Surface ◽  
Land Reclamation ◽  
Effective Pressure ◽  
Pressure Drops ◽  
Impact Performance ◽  
Theoretical Approaches ◽  
Rain Drops ◽  
Artificial Rain ◽  
Newton’S Laws ◽  
The Impact

The article considers the problem of calculating the vertical effective pressure drops of artificial rain on soil and hard surfaces. It is noted that the problem of determining the effective vertical pressure p of rain drops on soil although it is difficult, however, has a solution using Newton’s laws. This issue V.V. Slastenin, G. and A.P. Isaev, V.M. Moskovkin and V.F. gahs, etc., and N scientists. Erowyn S. , M.B. Lebedev, V.I., Gorodnichev, etc. proposed different approaches for determining the pressure p in terms of land reclamation (artificial irrigation). These issues dealt with and foreign researchers. Selected according to, according to the authors, the most suitable for the study of impact of the drops of artificial rain with the help of the patented device, and also to compare the obtained results with those of researchers dealing with the drip of erosion and determining the impact performance characteristics of droplets on a solid surface.

Effect of Secondary Force on Rigidity of Oil Film of the Slipper Pair Based on Hydrostatic Support

2012 ◽  
Vol 468-471 ◽  
pp. 1380-1383
Author(s):  
Hui Wang ◽  
Yu Xin Wang
Keyword(s):  
Computer Simulation ◽  
Friction Coefficient ◽  
Simulation Model ◽  
Dynamic Characteristics ◽  
Mathematics Model ◽  
Support Structure ◽  
Oil Film ◽  
Work Pressure ◽  
The Impact

Rigidity of oil film is an important hydrostatic support performance of the slipper pair. This paper establishes the mathematics model of hydrostatic support structure on the basis of considering secondary force. And establish the simulation model of rigidity of oil film by using the toolbox of Simulink. Study the dynamic characteristics of rigidity of oil film under the influence of secondary force through computer simulation. And reach a conclusion that the impact of secondary force on rigidity of oil film has a relationship with friction coefficient and work pressure.

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