scholarly journals Research on the Vertical Vibration Characteristics of Hydraulic Screw Down System of Rolling Mill under Nonlinear Friction

Processes ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 792 ◽  
Author(s):  
Yongshun Zhang ◽  
Wanlu Jiang ◽  
Yong Zhu ◽  
Zhenbao Li
Keyword(s):  
Parameter Uncertainty ◽  
Rolling Mill ◽  
Pid Controller ◽  
Vertical Vibration ◽  
Damping Coefficient ◽  
Practical Significance ◽  
Nonlinear Friction ◽  
Equivalent Damping ◽  
Leakage Coefficient ◽  
Equivalent Damping Coefficient

The rolling mill with hydraulic system is widely used in the production of strip steel. For the problem of vertical vibration of the rolling mill, the effects of different equivalent damping coefficient, leakage coefficient, and proportional coefficient of the controller on the hydraulic screw down system of the rolling mill are studied, respectively. First, a vertical vibration model of a hydraulic screw down system was established, considering the nonlinear friction and parameter uncertainty of the press cylinder. Second, the correlation between different equivalent damping coefficient, internal leakage coefficient, proportional coefficient, vertical vibration was analyzed. The simulation results show that, in the closed-loop state, when Proportional-Integral-Derivative (PID) controller parameters are fixed, due to the change of the equivalent damping coefficient and internal leakage coefficient, the system will have parameter uncertainty, which may lead to the failure of the PID controller and the vertical vibration of the system. This study has theoretical and practical significance for analyzing the mechanism of vertical vibration of the rolling mill.

The Calculation of the Equivalent Linear Damping Coefficient of the Magnetorheological Damper

2013 ◽  
Vol 336-338 ◽  
pp. 475-479 ◽  
Author(s):  
Yao Hui Guo ◽  
En Wei Chen ◽  
Qun Wu ◽  
Yi Min Lu ◽  
Zeng Qiang Xia
Keyword(s):  
Mr Damper ◽  
Magnetorheological Damper ◽  
Damping Coefficient ◽  
Control Voltage ◽  
Characteristic Analysis ◽  
Equivalent Damping ◽  
Equivalent Linear ◽  
Linear Damping ◽  
Damper Control ◽  
Equivalent Damping Coefficient

MR damper (magnetorheological damper) has broad application prospects, and equivalent damping coefficient is very important of its dynamic characteristic analysis. Based on the modified Bouc_Wen model, the performance of MR damper was analyzed and the equivalent linear damping coefficient of MR damper was calculated. Based on simulation date of the modified Bouc_Wen model, the relationships between the equivalent linear damping coefficient of MR damper and the parameters of control voltage and MR dampers movement amplitude were established by the curve fitting regression analysis method. Verification results prove that the equivalent linear damping coefficient model has higher accuracy. For the vibration systems using strongly nonlinear MR damper, new model can effectively improve the efficiency of calculating the vibration analysis and the stability of the system in a certain frequency. At the same time, the model provides a theoretical basis for the application of MR damper control.

A new type of damper combining eddy current damping with rack and gear

2020 ◽  
pp. 107754632093711
Author(s):  
Yafeng Li ◽  
Shouying Li ◽  
Jianzhong Wang ◽  
Zhengqing Chen
Keyword(s):  
Eddy Current ◽  
Permanent Magnets ◽  
Air Gap ◽  
Damping Coefficient ◽  
Apparent Mass ◽  
Damping Force ◽  
Equivalent Damping ◽  
Eddy Current Damping ◽  
New Type ◽  
Equivalent Damping Coefficient

A new type of damper combining eddy current damping with rack and gear, which can simultaneously export damping and inertial forces, is proposed. Eddy current damping with rack and gear is supposed to be installed between the building superstructure and foundation to mitigate the seismic response of the building. First, the concept of eddy current damping with rack and gear is introduced in detail and its apparent mass and equivalent damping coefficient are both theoretically investigated. Second, a prototype of eddy current damping with rack and gear is manufactured, and a series of tests on the prototype are carried out to verify its structural parameters. The experimental and theoretical results of the apparent mass of the prototype agree well with each other. The experimental result of the equivalent damping coefficient of the prototype is slightly lower than the numerical results obtained from COMSOL Multiphysics and its maximum relative differences are 11.3% and 13.6% for α = 0° and 45°, respectively. Third, detailed parametric studies on the damping force, including the effects of the thickness of the conductor plate, air gap, and number and location of permanent magnets, are conducted. The results show that the damping force keeps a linear relationship with velocity if it is lower than 0.15 m/s, and with the increase of the velocity, a strong nonlinear relationship between the damping force and the velocity is observed. The available maximum damping force can be increased by decreasing the thickness of the conductor plate and the air gap, increasing the number of permanent magnets. There is an optimal location about the permanent magnets for the available maximum damping force. In addition, the hysteretic curves of the eddy current damping with rack and gear obtained from the test indicate that the ability of energy dissipation is considerable.

scholarly journals Study on Equivalent Viscous Damping Coefficient of Sucker Rod Based on the Principle of Equal Friction Loss

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Qin Li ◽  
Bo Chen ◽  
Zhiqiang Huang ◽  
Haipin Tang ◽  
Gang Li ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Friction Loss ◽  
Damping Coefficient ◽  
Theoretical Formula ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Equivalent Damping ◽  
Rod System ◽  
Sucker Rod ◽  
Equivalent Damping Coefficient

Equivalent viscous damping coefficient is an important parameter of wave equation for sucker rod string. In this paper, based on the principle of equal friction loss, when the viscous energy consumption and the local damping energy consumption are taken into account, effects of equivalent viscous damping coefficients are obtained. Through deducing energy consumption equation of oil and energy consumption equation of the coupling, theoretical formula for equivalent damping coefficient of sucker rods is received. Results show that the smaller the K is (K is the ratio of sectional area of tubing to sucker rod), the larger the proportion of damping coefficient caused by viscous energy consumption in the equivalent damping coefficient of sucker rod system is. When K< 0.095, the proportion of damping coefficient caused by viscous energy consumption is more than 90%. Reducing the sudden change of cross-section area at sucker rod coupling has remarkable effect on reducing damping force of the sucker rod system. The research provides a theoretical basis for the application and design of sucker rod and tubing.

scholarly journals Study on Dynamic Characteristics of Aerostatic Bearing with Elastic Equalizing Pressure Groove

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Xiao-long Zhao ◽  
Hao Dong ◽  
Zhou Fang ◽  
Deng-di Chen ◽  
Jun-an Zhang
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Coupling Model ◽  
Damping Coefficient ◽  
Aerostatic Bearing ◽  
Equivalent Damping ◽  
New Type ◽  
Equivalent Damping Coefficient ◽  
Control Equation

Microvibration has an important influence on the dynamic performance of aerostatic bearings. Dynamic stiffness and equivalent damping coefficient are the main indexes to evaluate the dynamic characteristics of the aerostatic bearing. In order to study the dynamic characteristics of a new type of aerostatic bearing with the elastic equalizing pressure groove (EEPG), the dynamic characteristics of the new type of bearing are studied by theoretical calculation and experiment. First, the dynamic gas-solid coupling control equation is established. Then, the steady term and the perturbation term are decomposed by the perturbation method. By solving the coupling model, the dynamic characteristics of the bearing are calculated and analyzed. The calculation results show that the perturbation frequency has a significant effect on the dynamic stiffness and equivalent damping coefficient of the aerostatic bearing with EEPG. The dynamic stiffness increases with the increase of frequency, and the equivalent damping coefficient decreases with the increase of frequency. The experimental results are basically the same with the theoretical results, which effectively verify the correctness of the theoretical analysis.

Optimization of the Rollers System of Aluminum Strip Rolling Mill Based on the Stochastic Vibration

2010 ◽  
Vol 34-35 ◽  
pp. 544-550
Author(s):  
Bao Yu Xu ◽  
Yi Lun Liu ◽  
Xu Dong Wang ◽  
Fang Dong ◽  
Zhi Cheng Kang
Keyword(s):  
Mathematical Model ◽  
Natural Frequency ◽  
Dynamic Behavior ◽  
Rolling Mill ◽  
Vertical Vibration ◽  
Damping Coefficient ◽  
Hot Strip Rolling ◽  
Strip Rolling ◽  
Hot Strip ◽  
Roller System

The dynamic behavior of roller system of a "1+4" hot strip rolling tandem mill were analyzed. The stochastic vertical vibration and the optimum mathematical model were established based on the reliability after the system simplified to some extent. Stochastic optimum has been done to the system according to the optimum mathematical model of the roller system. Its best natural frequency and damping coefficient are obtained by computer simulation under the situation of minimum response of the rollers stationary acceleration when chatter occurs. The results indicate that by optimizing the natural frequency and damping coefficient of the system can greatly improve the dynamic behavior of rollers system and equality of the strip, and are useful to the new design of the rolling mill and the setting up of the rolling parameters.

EVALUATIONS OF CLUSTER STRUCTURE AND MAGNETO-RHEOLOGY OF MR SUSPENSIONS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1437-1442 ◽  
Author(s):  
HIDEYA NISHIYAMA ◽  
KAZUNARI KATAGIRI ◽  
KATSUHISA HAMADA ◽  
KAZUTO KIKUCHI ◽  
KATSUHIKO HATA ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Cluster Formation ◽  
Cluster Structure ◽  
Mr Damper ◽  
Magnetic Flux Density ◽  
Equivalent Damping ◽  
Damping Characteristics ◽  
Mr Fluids ◽  
Equivalent Damping Coefficient ◽  
Particle Shapes

In the present study, we sysnthesize two types of MR fluids with different particle shapes and sizes. The magnetic functions are evaluated circulatingly by the analysis of cluster formation, rheological properties in the applied magnetic field and damping characteristics in the MR damper, comparing with those of commercial MR fluids. Final objective is to provide the fundamental data for the development of newly advanced MR fluids. The main topics consist of geographycal cluster formation depending on particle shapes and sizes, relating to the apparent viscosity and yield stress with magnetic flux density and further equivalent damping coefficient of two newly sysnthesised MR fluids comparing with those of LORD MR fluid.

Fabrication and characterization of highly controllable magnetorheological material in compression mode

2020 ◽  
Vol 31 (14) ◽  
pp. 1641-1661 ◽  
Author(s):  
Amin Fereidooni ◽  
Afonso Martins ◽  
Viresh Wickramasinghe ◽  
Afzal Suleman
Keyword(s):  
Magnetic Fields ◽  
Loss Factor ◽  
Magnetorheological Fluid ◽  
Loading Frequency ◽  
Magnetorheological Elastomer ◽  
Magnetorheological Elastomers ◽  
Equivalent Damping ◽  
Magnetorheological Effect ◽  
Equivalent Damping Coefficient

This article is focused on the development and characterization of highly controllable magnetorheological materials for stiffness and damping control in semi-active control applications. Two types of magnetorheological materials are developed in-house: magnetorheological elastomer with soft base elastomer, and magnetorheological fluid encapsulated in regular elastomer, namely magnetorheological fluid-elastomer. In both cases of magnetorheological elastomers and magnetorheological fluid-elastomers, the samples are evaluated using in-house-developed shear and compression test rigs, which are equipped with electromagnets and Hall effect sensors for measuring the magnetic field. These features provide the capability to precisely control a wide range of magnetic fields during the experiments. In the case of magnetorheological elastomers, the experimental results of the in-house magnetorheological elastomers are compared with commercially available counterparts made of hard base elastomer. It is shown that the controllability of the material, that is, the relative magnetorheological effect, is significantly improved in the case of magnetorheological elastomer with soft base elastomer. In addition to various magnetic fields, the samples are subjected to a range of loading amplitudes and frequencies. A general trend is observed where the frequency and strain amplitude cause an opposite effect on both the shear and compressive moduli: the increase in frequency gives rise to a higher value of modulus whereas the increase in amplitude reduces the modulus. Furthermore, the effect of bonding on the performance of the magnetorheological elastomers in compression mode is evaluated and the results indicate a significant increase in the modulus and decrease in the loss factor. In all the cases, however, the change of loss factor does not exhibit a predictable trend as a function of magnetic fields. In order to investigate a magnetorheological-based solution for controlling the damping of a semi-active system, magnetorheological fluid-elastomer samples are made in-house. These samples are fabricated using three different iron concentrations, and are tested in compression (squeeze) mode. The results of these experiments confirm that the equivalent damping coefficient of the material rises with the increase in magnetic field, and this effect becomes stronger as the iron concentration of magnetorheological fluids increases. It is also demonstrated that the magnetorheological effect is highly dependent on the loading frequency and amplitude, where the equivalent damping coefficient decreases with the increase in loading frequency and amplitude. In all the aforementioned cases, the stiffness of magnetorheological fluid-elastomers exhibits minor changes, which offers the in-house-developed magnetorheological fluid-elastomers as a damping only control option, a development that is different from the magnetorheological fluid-elastomers reported in the literature.

Study on Dynamical Modeling of the Rolling Mill Vertical System

2011 ◽  
Vol 383-390 ◽  
pp. 4825-4830
Author(s):  
Xian Jin Shi ◽  
Di Ping Wu ◽  
Zhi Ying Gao
Keyword(s):  
Rolling Mill ◽  
Stand Structure ◽  
Contact Stiffness ◽  
Work Roll ◽  
Vertical Vibration ◽  
Ansys Simulation ◽  
Rigid Body Model ◽  
Rigid Model ◽  
Mill Stand ◽  
Vertical System

Vertical vibration is universal in the vertical system of rolling mill. It has a seriously bad effect on the quality of strip. Dynamic model of the vertical system plays an important role in the analysis of vertical vibration in rolling mill. On the basis of 1420mm six roller cold rolling mill, ADAMS rigid model and flexibility model are established in this paper. Contact stiffness of rollers is calculated through ansys simulation. Contact stiffness between the work-roll and strip is calculated by using theoretical methods and stiffness of mill stand is calculated by simplifying mill stand structure. Natural frequency and some amplitude-frequency response of vertical vibration are analyzed. The test results prove that the modeling method is feasible. Vibration derived from the deformation of rolls can be observed directly in the flexible model, which can’t be realized in the rigid body model. At the same time, the new method of calculating vertical system stiffness is also proved to be reasonable.

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