Experimental study of the nature of the load distribution on the turns of the thread of the planetary roller-screw mechanism

2019 ◽  
Author(s):  
O.A. Ryakhovskiy ◽  
A.S. Marokhin ◽  
A.N. Vorobyev ◽  
O.A. Khachirova
Keyword(s):  
Load Distribution ◽  
Axial Load ◽  
Flat Surface ◽  
Experimental Setup ◽  
Feed Drives ◽  
The Press ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Force Displacement ◽  
Made In

The article considers the effect of axial load on the turns of the thread of the planetary roller-screw converter of rotational motion into translational one. For this purpose an experimental setup was made in which the nut lies end-face on the flat surface of the press, a screw is screwed into it. The force is applied to the screw through a ball to distribute the load uniformly. The design of the machine for compression measurement allows automatic recording the axial mutual movement of tested mechanism parts when the loading force changes. Contact and displacement occur when the loading force reaches 300 N. The results are obtained in the form of a "force – displacement" graph. In the course of the experiment, the influence of step error on the uniformity of the contacts of the turns of the mating parts of the planetary roller-screw mechanism was checked. The results of the experiment are analyzed, the influence of inaccuracy of manufacturing thread of planetary roller-screw mechanism parts on its capacity for use in feed drives of various machines is considered.

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.

scholarly journals Thermo-mechanical coupling–based finite element analysis of the load distribution of planetary roller screw mechanism

2018 ◽  
Vol 10 (6) ◽  
pp. 168781401877525 ◽  
Author(s):  
Shangjun Ma ◽  
Chenhui Zhang ◽  
Tao Zhang ◽  
Geng Liu ◽  
Shumin Liu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Load Distribution ◽  
Three Dimensional ◽  
Theoretical Models ◽  
Element Model ◽  
Element Analysis ◽  
Mechanical Coupling ◽  
Roller Screw ◽  
Screw Mechanism

In this article, 3D or three-dimensional finite element analysis is used to simulate and evaluate the load distribution characteristics of a planetary roller screw mechanism under thermo-mechanical coupling. The finite element model takes into account the installation modes of the planetary roller screw mechanism, which is verified by comparison with theoretical models for a certain load magnitude in four installation modes. In addition, the effects of the installation mode, load magnitude, and temperature condition on the load distribution are also systematically analyzed. The numerical results reveal a phenomenon of threads separating from the meshing, which indicates that the influence of thermo-mechanical coupling on the load distribution cannot be ignored. Furthermore, the influence of the installation mode on the screw–roller interface is larger than that on the nut–roller interface. Compared with the screw–roller interface, the temperature difference is one of the main conditions affecting the load distribution of the planetary roller screw mechanism and has a significant effect on the nut–roller interface. In addition, the influences of the screw rotational speed and the load magnitude on the load distribution on the screw–roller interface are larger than those on the nut–roller interface for the four installation modes.

Load Distribution and Axial Static Rigidity for Planetary Roller Screw Mechanism

2019 ◽  
Author(s):  
Xinhua Zhang ◽  
Xijian Huo ◽  
Jian Huang ◽  
Xiaoshuai Duan ◽  
Wei Zhou ◽  
...  
Keyword(s):  
Load Distribution ◽  
Roller Screw ◽  
Static Rigidity ◽  
Screw Mechanism

scholarly journals Thread Modification Method for Load Balance on Planetary Roller Screw Mechanism

2018 ◽  
Vol 36 (4) ◽  
pp. 685-692
Author(s):  
Hui Guo ◽  
Ruiting Tong ◽  
Geng Liu ◽  
Wenjie Zhang ◽  
Shangjun Ma
Keyword(s):  
Load Balancing ◽  
Load Balance ◽  
Load Distribution ◽  
Load Capacity ◽  
Optimal Value ◽  
Modification Method ◽  
The Future ◽  
Roller Screw ◽  
Screw Mechanism ◽  
The Relationship

Based on the relationship between the load distribution and the load deformation of the thread of the planetary roller screw mechanism (PRSM), a modification method of the roller thread is proposed. The nut side and the screw side of the roller thread are modified by different amount of modification, and the modified thread load distribution is calculated and analyzed. The results show that the effects of roller thread modification on the load distribution are significant, and the sensitivity of the load capacity of the nut and screw to the modification is different. Through the study of the influence of roller thread modification on thread load distribution, the optimal value of the roller thread modification on the nut side and the screw side is obtained under the PRSM parameters given in this paper, which provides a theoretical guidance for the future PRSM load balancing design.

scholarly journals Research on friction torque analysis of planetary roller screw mechanism considering load distribution

2018 ◽  
Author(s):  
Fajin Gan ◽  
Pengcheng Mao ◽  
Shicheng Zheng ◽  
Guangliang Li ◽  
Shupeng Xin
Keyword(s):  
Load Distribution ◽  
Friction Torque ◽  
Roller Screw ◽  
Torque Analysis ◽  
Screw Mechanism

Load distribution of planetary roller screw mechanism and its improvement approach

2016 ◽  
Vol 230 (18) ◽  
pp. 3304-3318 ◽  
Author(s):  
Wenjie Zhang ◽  
Geng Liu ◽  
Ruiting Tong ◽  
Shangjun Ma
Keyword(s):  
Load Distribution ◽  
Applied Load ◽  
Uniform Load ◽  
Contact Conditions ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Deformation Compatibility ◽  
Load Conditions ◽  
Force Equilibrium

A model of load distribution over threads of planetary roller screw mechanism (PRSM) is developed according to the relationships of deformation compatibility and force equilibrium. In order to make the applied load of PRSM uniformly distributed over threads, an improvement approach is proposed, in which the parameters of thread form of roller and nut are redesigned, and the contact conditions of roller with screw and nut are changed to compensate the axial accumulative deformation of shaft sections of screw and nut. A typical planetary roller screw mechanism is taken as example to analyze the load distribution, and the effects of installation configurations, load conditions and thread form parameters on load distribution are studied. Furthermore, the improvement approach is applied to the PRSM, and it is proved to be beneficial to reach uniform load distribution over threads.

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.

The "Right to Die": A Case Study in American Lawmaking*

1996 ◽  
Vol 3 (1) ◽  
pp. 49-74
Author(s):  
Alan Meisel
Keyword(s):  
Legal System ◽  
Right To Die ◽  
Judicial Process ◽  
Clinical Issue ◽  
The Press ◽  
American Law ◽  
American Legal System ◽  
The Right ◽  
Made In

AbstractIn the 20 years that have passed since the Karen Quinlan case exposed a simmering clinical issue to the light of day — more precisely, to the press and to judicial process — a consensus has developed in American law about how end-of-life decisionmaking should occur. To be sure, there are dissenting voices from this consensus, but they are often (though not always) about minor issues. By illustrating how this consensus has evolved, this paper explores how law is made in the American legal system and the roles that different legal and extra-legal institutions play in lawmaking.

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