Investigation of load distribution and deformations for ball screws with the effects of turning torque and geometric errors

2019 ◽  
Vol 141 ◽  
pp. 95-116 ◽  
Author(s):  
Jiajia Zhao ◽  
Mingxing Lin ◽  
Xianchun Song ◽  
Qizhen Guo
Keyword(s):  
Load Distribution ◽  
Geometric Errors

Low Order Static Load Distribution Model for Ball Screw Mechanisms Including Effects of Lateral Deformation and Geometric Errors

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Bo Lin ◽  
Chinedum E. Okwudire ◽  
Jason S. Wou
Keyword(s):  
Load Distribution ◽  
Static Load ◽  
High Order ◽  
Contact Model ◽  
Ball Screw ◽  
Distribution Model ◽  
Computational Time ◽  
Geometric Errors ◽  
Lateral Deformation ◽  
Low Order

Accurate modeling of static load distribution of balls is very useful for proper design and sizing of ball screw mechanisms (BSMs); it is also a starting point in modeling the dynamics, e.g., friction behavior, of BSMs. Often, it is preferable to determine load distribution using low order models, as opposed to computationally unwieldy high order finite element (FE) models. However, existing low order static load distribution models for BSMs are inaccurate because they ignore the lateral (bending) deformations of screw/nut and do not adequately consider geometric errors, both of which significantly influence load distribution. This paper presents a low order static load distribution model for BSMs that incorporates lateral deformation and geometric error effects. The ball and groove surfaces of BSMs, including geometric errors, are described mathematically and used to establish a ball-to-groove contact model based on Hertzian contact theory. Effects of axial, torsional, and lateral deformations are incorporated into the contact model by representing the nut as a rigid body and the screw as beam FEs connected by a newly derived ball stiffness matrix which considers geometric errors. Benchmarked against a high order FE model in case studies, the proposed model is shown to be accurate in predicting static load distribution, while requiring much less computational time. Its ease-of-use and versatility for evaluating effects of sundry geometric errors, e.g., pitch errors and ball diameter variation, on static load distribution are also demonstrated. It is thus suitable for parametric studies and optimal design of BSMs.

scholarly journals Online Bearing Clearance Monitoring Based on an Accurate Vibration Analysis

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 389 ◽  
Author(s):  
Jianguo Wang ◽  
Minmin Xu ◽  
Chao Zhang ◽  
Baoshan Huang ◽  
Fengshou Gu
Keyword(s):  
Load Distribution ◽  
Lead Time ◽  
Cost Effective ◽  
Local Defect ◽  
Geometric Errors ◽  
Distribution Method ◽  
Outer Race ◽  
Bearing Clearance ◽  
Optimal Maintenance ◽  
Local Defects

Accurate diagnosis of incipient faults in wind turbine (WT) assets will provide sufficient lead time to apply an optimal maintenance for the expensive WT assets which often are located in a remote and harsh environment and their maintenance usually needs heavy equipment and highly skilled engineers. This paper presents an online bearing clearance monitoring approach to diagnose the change of bearing clearance, providing an early and interpretable indication of bearing health conditions. A novel dynamic load distribution method is developed to efficiently gain the general characteristics of vibration response of bearings without local defects but with small geometric errors. It shows that the ball pass frequency of outer race (BPFO) is the primary exciting source due to biased load distribution relating to bearing clearance. The geometric errors, including various orders of runouts on different bearing parts, can be the secondary excitation source. Both sources lead to compound modulation responses with very low amplitudes, being more than 20 dB lower than that of a small local defect on raceways and often buried by background noise. Then, Modulation Signal Bispectrum (MSB) is identified to purify the noisy signal and Gini index is introduced to represent the peakness of MSB results, thereby an interpretable indicator bounded between 0 and 1 is established to show bearing clearance status. Datasets from both a dedicated bearing test and a run-to-failure gearbox test are employed to verify the performance and reliability of the proposed approach. Results show that the proposed method is capable to indicate a change of about 20 µm in bearing clearance online, which provides a significantly long lead time compared to the diagnosis method that focuses only on local defects. Therefore, this method provides a big opportunity to implement more cost-effective maintenance works or carry out timely remedial actions to prolong the lifespan of bearings. Obviously, it is applicable to not only WT assets, but also most rotating machines.

A Modular Race Tire Model Concerning Thermal and Transient Behavior using a Simple Contact Patch Description

2013 ◽  
Vol 41 (4) ◽  
pp. 232-246
Author(s):  
Timo Völkl ◽  
Robert Lukesch ◽  
Martin Mühlmeier ◽  
Michael Graf ◽  
Hermann Winner
Keyword(s):  
Load Distribution ◽  
Thermal Condition ◽  
Transient Behavior ◽  
Wheel Load ◽  
Contact Patch ◽  
Fundamental Parameters ◽  
Dry Conditions ◽  
Simple Contact ◽  
Tire Forces ◽  
Descriptive Set

ABSTRACT The potential of a race tire strongly depends on its thermal condition, the load distribution in its contact patch, and the variation of wheel load. The approach described in this paper uses a modular structure consisting of elementary blocks for thermodynamics, transient excitation, and load distribution in the contact patch. The model provides conclusive tire characteristics by adopting the fundamental parameters of a simple mathematical force description. This then allows an isolated parameterization and examination of each block in order to subsequently analyze particular influences on the full model. For the characterization of the load distribution in the contact patch depending on inflation pressure, camber, and the present force state, a mathematical description of measured pressure distribution is used. This affects the tire's grip as well as the heat input to its surface and its casing. In order to determine the thermal condition, one-dimensional partial differential equations at discrete rings over the tire width solve the balance of energy. The resulting surface and rubber temperatures are used to determine the friction coefficient and stiffness of the rubber. The tire's transient behavior is modeled by a state selective filtering, which distinguishes between the dynamics of wheel load and slip. Simulation results for the range of occurring states at dry conditions show a sufficient correlation between the tire model's output and measured tire forces while requiring only a simplified and descriptive set of parameters.

Dynamic Service Placement and Load Distribution in Edge Computing

2020 ◽  
Author(s):  
Adyson Magalhaes Maia ◽  
Yacine Ghamri-Doudane ◽  
Dario Vieira ◽  
Miguel Franklin de Castro
Keyword(s):  
Load Distribution ◽  
Edge Computing ◽  
Service Placement

Comparative assessment of rubber steel cables for vertical mine hoists

2020 ◽  
pp. 85-93
Author(s):  
V. E. Perekutnev ◽  
V. V. Zotov
Keyword(s):  
Feasibility Study ◽  
Carrying Capacity ◽  
Load Distribution ◽  
Comparative Assessment ◽  
Life Extension ◽  
Steel Cable ◽  
Motion Stability ◽  
Cable Length ◽  
Steel Cables ◽  
Mine Hoist

Operation of inhaul rubber steel cables in vertical mine hoisting is discussed. The research in the field of mine hoisting is reviewed, and the further R&D directions are identified. Some studies concern life extension of hoisting ropes. One of the promising trends seems to be application of belt pullers as inhaul cables, which can essentially enhance mine hoist efficiency. In the meanwhile, capabilities of rubber steel cables suffer from deficient attention. The performance capabilities of rubber steel cables of top manufacturers (Promkanat and SAG) are compared, and application ranges in vertical mine hoisting are determined for such cables. It is found that the Polish manufacturer’s rubber steel cables offer a wider range of application. The analysis shows that rubber steel cables can be used as inhaul cables of vertical mine hoisters. Rubber steel cables possess suitable characteristics and are capable to elevate considerable loads to various hoisting heights. In particular, the existing rubber steel cables ensure carrying capacity of hoists up to 20-25 t at the hoisting heights to 400-500 m and sometimes can elevate skips with tonnage of 10 t to a height up to 1000 m and more. The further feasibility study of operation of inhaul steel rubber cables in hoisting units should address motion stability of a puller on a driving drum, load distribution in ropes of base of rubber steel cables, validation of hoister design, adjustability of rubber steel cable length during its operation, etc.

Load distribution in cylindrical roller bearing with EHD lubricated contact force

2019 ◽  
Author(s):  
Natália Akemi Hoshikawa Tsuha ◽  
Fabio Nonato ◽  
Katia Lucchesi Cavalca Dedini
Keyword(s):  
Contact Force ◽  
Load Distribution ◽  
Roller Bearing ◽  
Lubricated Contact ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller
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