Dynamic Stiffness Model of Planetary Roller Screw Mechanism With Clearance, Geometry Errors and Rolling-Sliding Friction

2017 ◽  
Author(s):  
Shangjun Ma ◽  
Cheng Peng ◽  
Xiaofeng Li ◽  
Geng Liu
Keyword(s):  
Sliding Friction ◽  
Contact Stiffness ◽  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Helix Angle ◽  
Calculation Model ◽  
Load Distributions ◽  
Roller Screw ◽  
Screw Diameter ◽  
Screw Mechanism

This paper applies the bond graph theory to construct a dynamic stiffness calculation model for the planetary roller screw mechanism with factors such as structural stiffness and contact stiffness of screw, clearances, geometry errors, rolling-sliding friction, and load distributions on the roller threads and a group of rollers under two installation modes. In addition to predicting how dynamic stiffness varies with the load frequency and load amplitude under two installation modes, how does it change with the structural parameters such as screw diameter, helix angle, contact angle and number of roller threads under two installation modes are also investigated. The results can provide theoretical basis for the design of planetary roller screw mechanism considering dynamic stiffness with the influences of clearances, geometry errors, friction and installation modes.

Friction Torque Modelling and Efficiency Analysis of the Preloaded Inverted Planetary Roller Screw Mechanism

2017 ◽  
Author(s):  
Guan Qiao ◽  
Geng Liu ◽  
Shangjun Ma ◽  
Zhenghong Shi ◽  
Teik C. Lim
Keyword(s):  
Optimization Design ◽  
Sliding Friction ◽  
Helix Angle ◽  
Efficiency Analysis ◽  
Transmission Efficiency ◽  
Friction Torque ◽  
Operating Conditions ◽  
Design Parameters ◽  
Roller Screw ◽  
Screw Mechanism

The efficiency analytical model of the inverted planetary roller screw mechanism is formulated based on the friction torque calculation. Firstly, the friction torque model considering the load distribution of thread teeth is established including the components such as curvature friction torque, friction torque due to spinning sliding, pure sliding friction torque between rollers and carriers, friction torque generated by the viscosity of lubricant, and preload torque. Secondly, the contribution of the friction torque components and torque distribution on the roller thread teeth are investigated. Finally, efficiency analysis is conducted by discussing the influences of structure parameters of the inverted planetary roller screw mechanism and operating conditions. Computational results reveal that the total friction torque and efficiency are influenced by axial load, number of roller thread teeth, nut speed, contact angle, and helix angle of nut with different extents. This study provides an understanding of the relationship between friction torque, transmission efficiency, and system design parameters, which can be employed to enhance the inverted planetary roller screw mechanism optimization design.

scholarly journals Modelling of Electro-mechanical Servo System Based on the Planetary Roller Screw Mechanism

2020 ◽  
Vol 306 ◽  
pp. 02004
Author(s):  
Jianxin Zhang ◽  
Chuanming Du ◽  
Shangjun Ma ◽  
Geng Liu
Keyword(s):  
Contact Stiffness ◽  
Servo System ◽  
Response Speed ◽  
Load Force ◽  
System Response ◽  
Analysis Model ◽  
Roller Screw ◽  
Fluctuation Amplitude ◽  
Screw Mechanism ◽  
Main Components

Taking the electro-mechanical servo system as the research object, considering the contact stiffness, friction and clearance of the main components in the electro-mechanical servo system, the analysis model of the electro-mechanical servo system based on Planetary roller screw mechanism (PRSM) is established by using AMESim software. The results showed that the response speed of the system slowed down when the friction of PRSM was taken into account. The larger the clearance or the smaller the stiffness, the greater the fluctuation amplitude of the system response. After the controller was adjusted, the steady-state error of the system caused by the load force can be reduced quickly.

Load distribution over threads of planetary roller screw mechanism with pitch deviation

2018 ◽  
Vol 233 (13) ◽  
pp. 4653-4666 ◽  
Author(s):  
Wenjie Zhang ◽  
Geng Liu ◽  
Shangjun Ma ◽  
Ruiting Tong
Keyword(s):  
Load Distribution ◽  
Machining Error ◽  
Experimental Conditions ◽  
Load Distributions ◽  
Machining Errors ◽  
Proposed Model ◽  
Roller Screw ◽  
Multiple Threads ◽  
Screw Mechanism ◽  
Pitch Deviation

A model is proposed to calculate load distribution over threads of planetary roller screw mechanism (PRSM) with pitch deviation. Firstly, four kinds of machining errors of threads including pitch deviation, deviation of thread angle, division error of multiple threads and deviation of pitch diameter are analyzed, and the relationships among them are investigated. After analyzing the relationships among the errors, pitch deviation is chosen to be the main machining error to investigate because it can reflect the effects of other machining errors, and is the most influential machining error on the contact condition and deformation compatibility relationship, i.e. the load distribution of PRSM. Based on the proposed model, the effects of pitch deviation on the load distribution of PRSM are studied through numerical analyses, and load distributions under different machining precisions are analyzed. In order to experimentally verify the investigation, two PRSM samples are measured and tested under the same experimental conditions. The experimental results show that load distributions over threads will fluctuate because of the existence of pitch deviations. The pitch deviations, load distributions over threads and wear depths of threads in the samples show obvious accordance, which indirectly demonstrates the effects of pitch deviation on load distribution.

scholarly journals Loading Performance of a Novel Shearer Drum Applied to Thin Coal Seams

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 358
Author(s):  
Kuidong Gao ◽  
Xiaodi Zhang ◽  
Liqing Sun ◽  
Qingliang Zeng ◽  
Zhihai Liu
Keyword(s):  
Rotational Speed ◽  
Production Efficiency ◽  
Loading Rate ◽  
Positive Impact ◽  
Structural Parameters ◽  
Helix Angle ◽  
Structure Design ◽  
Coal Seams ◽  
Coal Particles ◽  
Relationship Of

The poor loading performance of shearer drums restricts the development and production efficiency of coal in thin coal seams. Changing operation and structural parameters can improve the drum’s loading performance to some extent, but the effect is not obvious. A two-segment differential rotational speed drum (TDRSD) was proposed after analyzing the drum’s influence mechanism on coal particles. To further reveal the drum’s coal loading principle, the velocity, particles distribution, and loading rate were analyzed. The effect of the matching relationship of the rotational speed and helix angle between the front and rear drum are also discussed. The results show that a lower front drum rotational speed had a positive impact on improving the loading performance, and the loading rate first increases and then decreases with the increase in rear drum rotational speed. The optimal loading performance was obtained in the range 60–67.5 rpm. The front drum’s helix angle had no evident effect on loading performance, and the loading rate increase with the increase in the rear drum’s helix angle. The results provide a reference and guidance for operation parameters selection, structure design, and drum optimization.

Grinding Force Model for Low-Speed Grinding Based on Impact Principle

2013 ◽  
Vol 797 ◽  
pp. 123-128
Author(s):  
Ming He Liu ◽  
Xiu Ming Zhang ◽  
Shi Chao Xiu
Keyword(s):  
Sliding Friction ◽  
Impact Load ◽  
Grinding Force ◽  
Calculation Model ◽  
Force Model ◽  
Grinding Process ◽  
Low Speed ◽  
Impact Area ◽  
Force Mechanism ◽  
The Impact

In the low-speed grinding process, the force generated when the wheel grinding the workpiece is the result of sliding friction, plough and cutting. While in the actual study, the cutting process has attracted extensive attention. Impact effect to the entire grinding process on the contact is ignored so that the error exists between the calculation grinding force and the measured grinding force. Basing on the shock effect to the grinding process, the paper divides the contact area into impact area and cutting area. And the model of impact load generated from single grit is built. Moreover, the grinding force theoretical calculation model and total grinding force mathematical model is also constructed by analyzing the impact load affecting on the grinding force mechanism. Finally experimental study verifies the correctness of theoretical analysis.

scholarly journals Hybrid Bandgaps in Mass-coupled Bragg Atomic Chains: Generation and Switching

2021 ◽  
Vol 8 ◽  
Author(s):  
Shao-Feng Xu ◽  
Zhu-Long Xu ◽  
Kuo-Chih Chuang
Keyword(s):  
Structural Parameters ◽  
Dynamic Stiffness ◽  
Detailed Examination ◽  
Acoustic Metamaterials ◽  
Acoustic Metamaterial ◽  
Chain System ◽  
Different Types ◽  
Atomic Chains ◽  
Amplification System ◽  
Three Degree Of Freedom

In this work, without introducing mass-in-mass units or inertial amplification mechanisms, we show that two Bragg atomic chains can form an acoustic metamaterial that possesses different types of bandgaps other than Bragg ones, including local resonance and inertial amplification-like bandgaps. Specifically, by coupling masses of one monatomic chain to the same masses of a diatomic or triatomic chain, hybrid bandgaps can be generated and further be switched through the adjustment of the structural parameters. To provide a tuning guidance for the hybrid bandgaps, we derived an analytical transition parameter (p-value) for the mass-coupled monatomic/diatomic chain and analytical discriminants for the mass-coupled monatomic/triatomic chain. In our proposed mass-coupled monatomic/triatomic chain system, each set of analytical discriminants determines a hybrid bandgap state and a detailed examination reveals 14 different bandgap states. In addition to bandgap switching, the analytical p-value and discriminants can also be used as a guide for designing the coupled-chain acoustic metamaterials. The relations between the mass-coupled monatomic/triatomic chain system and a three-degree-of-freedom (DOF) inertial amplification system further indicate that the band structure of the former is equivalent to that of the latter through coupling masses by negative dynamic stiffness springs.

Lastverteilung in Planetenrollengewindetrieben/Description of the load distribution in planetary roller screws

2020 ◽  
Vol 110 (05) ◽  
pp. 322-327
Author(s):  
Christian Brecher ◽  
Thomas Frenken ◽  
Gabriel Axelrad ◽  
Stephan Neus
Keyword(s):  
Load Distribution ◽  
Load Capacity ◽  
Calculation Model ◽  
Axial Stiffness ◽  
Contact Points ◽  
Calculation Results ◽  
Roller Screw ◽  
The Individual ◽  
Individual Contact ◽  
High Load Capacity

Planetenrollengewindetriebe finden aufgrund ihrer hohen Tragfähigkeit Anwendung in Bereichen, in denen Kugelgewindetriebe an ihre Lastgrenzen stoßen. Um ein Berechnungsmodell für Planentenrollengewindetriebe zu entwickeln, wurden Berechnungsmethoden zur Beschreibung der Lastverteilung innerhalb des Planetenrollengewindetriebs entwickelt. Mit diesen lassen sich die in den einzelnen Kontaktpunkten wirkenden Kräfte sowie die Verlagerungen des Gewindetriebs bestimmen. Die Berechnungsergebnisse werden unter anderem für die Berechnung der statischen axialen Steifigkeit und der Ermüdungslebensdauer benötigt.   Due to their high load capacity, planetary roller screws are used in areas where ball screws reach their load limits. To develop a calculation model for planetary roller screws, calculation methods to describe the load distribution within the planetary roller screw were developed in this step. With these methods, the forces acting in the individual contact points as well as the displacements of the screw drive can be determined. The calculation results are required, among other things, for the calculation of static axial stiffness and fatigue life.

Dynamic Modeling of the Double-Nut Planetary Roller Screw Mechanism Considering Elastic Deformations

2021 ◽  
Author(s):  
Xiaojun Fu ◽  
Geng Liu ◽  
Xin Li ◽  
Ma Shangjun ◽  
Qiao Guan
Keyword(s):  
External Force ◽  
Load Distribution ◽  
Equations Of Motion ◽  
Great Influence ◽  
Compressive Force ◽  
Mass System ◽  
Elastic Deformations ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Nonlinear Equations Of Motion

Abstract With the rising application of double-nut Planetary Roller Screw Mechanism (PRSM) into industry, increasing comprehensive studies are required to identify the interactions among motion, forces and deformations of the mechanism. A dynamic model of the double-nut PRSM with considering elastic deformations is proposed in this paper. As preloads, inertial forces and elastic deformations have a great influence on the load distribution among threads, the double-nut PRSM is discretized into a spring-mass system. An adjacency matrix is introduced, which relates the elastic displacements of nodes and the deformations of elements in the spring-mass system. Then, the compressive force acting on the spacer is derived and the equations of load distribution are given. Considering both the equilibrium of forces and the compatibility of deformations, nonlinear equations of motion for the double-nut PRSM are developed. The effectiveness of the proposed model is verified by comparing dynamic characteristics and the load distribution among threads with those from the previously published models. Then, the dynamic analysis of a double-nut PRSM is carried out, when the rotational speed of the screw and the external force acting on the nut #2 are changed periodically. The results show that if the external force is increased, the preload of the nut #1 is decreased and that of the nut #2 is increased. Although the nominal radii of rollers are the same, the maximum contact force acting on the roller #2 is much larger than that of the roller #1.

A Mathematical Calculation Method for Hysteresis Characteristics Analysis of Arc-Shaped Finger Seal

2020 ◽  
Author(s):  
Chun-Hua Du ◽  
Yan-Chao Zhang ◽  
Ya-Hui Cui ◽  
Shu-Na Dong ◽  
Hong-Hu Ji ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Structural Parameters ◽  
Maximum Error ◽  
Calculation Model ◽  
Correction Coefficient ◽  
Research Results ◽  
Characteristics Analysis ◽  
Leakage Characteristics ◽  
The Mathematical Model ◽  
Hysteresis Characteristics

Abstract In order to accurately predict the hysteresis characteristics of finger seal, the minimum hysteresis which can directly reflect the hysteresis of finger seal is proposed to characterize the hysteresis of finger seal. The mathematical model for calculating the minimum hysteresis of finger seal is established, the correction coefficient in the mathematical model is determined, and the mathematical model is verified by experiments. The influence of the structure and working condition parameters of finger laminates on the hysteresis characteristics is studied based on the modified calculation model, and the rule of influence is obtained in the end. Research results show that the maximum error between the leakage characteristics numerical calculation of finger seal base on modified calculation model and the experiment results is 7.64%, and the mathematical model of the minimum hysteresis is reasonable and reliable. The descending order of influence degree of structural parameters on the hysteresis characteristics of finger seal is: thickness of each finger laminate, finger repeat angle, arc radius of the finger beam arcs‘ centers, diameter of the finger base circle, width of the interstice between fingers, arc radius of finger beam. The research results provide a theoretical basis for further research on the influence of hysteresis on the finger seal leakage characteristics and the optimal design of finger seal structure.

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