Zhijian Wang, Yin Wang, Lin Liu, Wengsheng Zhu, Jing Li, Yujie Zhao, Haijun Pang and Qilong Wu
The aim of this study is to first investigate the surface integrity of cylindrical rollers under grinding process and then design a reasonable superfinishing process that improve…
Abstract
Purpose
The aim of this study is to first investigate the surface integrity of cylindrical rollers under grinding process and then design a reasonable superfinishing process that improve the anti-fatigue performance of cylindrical rollers by optimization of the surface integrity.
Design/methodology/approach
First, the white and dark layers produced by the grinding process is analyzed by microscope. Then, the influence of oilstone pressure on the stock removal, surface precision and crowned profile are explored. Finally, an optimal superfinishing process and a novel turnaround device are designed to improve surface integrity.
Findings
The experimental results show that as the oilstone pressure increases, the stock removal first increases and then remains stable. This hints that the stock removal of a single-time superfinishing process has an upper limit. In the current conditions, the maximum stock removal is 6 µm. Double-time superfinishing process and the turnover device can effectively eliminate the white and dark layers and improve the symmetric of roller profile. In addition, the surface precision is also improved.
Originality/value
The surface integrity of bearing rollers is very important to the application of industry field. The findings and the methods in the study can be helpful to improve the surface integrity of the bearing rollers.
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Zhijian Wang, Xuejin Shen, Xiaoyang Chen, Qiang Han and Lei Shi
The purpose of this paper is to study starvation in grease-lubricated finite line contacts and to understand film-forming mechanisms of grease-lubricated finite line contacts.
Abstract
Purpose
The purpose of this paper is to study starvation in grease-lubricated finite line contacts and to understand film-forming mechanisms of grease-lubricated finite line contacts.
Design/methodology/approach
A multiple-contact optical elastohydrodynamic (EHL) test rig is constructed to investigate the influences of lubricant properties on film thickness and lubrication conditions at different working conditions. The film thickness is calculated according to the relative light intensity principle. The degree of starvation is evaluated by the air–oil meniscus distance and the corresponding film thickness.
Findings
The experimental results show that for greases with high-viscosity base oil, the high-frequency fluctuation of film thickness is observed in low-speed operating conditions. Reducing the viscosity of the base oil and improving running speed can weaken the fluctuation of film thickness. The degree of starvation increases with increasing base oil viscosity, rolling speed and the crown drop. In addition, reducing the replenishment time by reducing the gap between the rollers also can increase the degree of starvation.
Originality/value
Starvation is often to occur in finite line contacts, such as roller bearings and gears; there are still limited finite line contact EHL test rigs, much less multiple-contact optical test rigs. Therefore, the present work is undertaken to construct the multiple-contact test rig and to evaluate the mechanism of starvation in finite line contacts.
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Hongyu Duan, Qingtao Yu and Zhijian Wang
The purpose of this paper is to study the film-forming capacity of logarithmic crowned roller for tapered roller bearing (TRB) and to design a tapered roller profile based on an…
Abstract
Purpose
The purpose of this paper is to study the film-forming capacity of logarithmic crowned roller for tapered roller bearing (TRB) and to design a tapered roller profile based on an elastohydrodynamic lubrication model.
Design/methodology/approach
A coupled model, incorporating a quasi-static model of TRBs and an elastohydrodynamic lubrication model was developed to investigate the load distribution of TRB and to evaluate the lubrication state of tapered roller/raceway contact.
Findings
The model is verified with published literature results. Parametric analysis is conducted to investigate the effect of crown drop on azimuthal load distribution of the roller, film thickness and pressure distribution in the contact area. The result shows that crown drop has little influence on the azimuthal load distribution; also, the film thickness and the pressure distribution are asymmetric. When the tapered roller is designed and manufactured, the crown drop of the small end should be larger than that in the large end.
Originality/value
Precise roller profile design is conducive to improve the fatigue life of TRBs. Currently, most crown design methods neglect the influence of lubrication, which can lead to a non-suitable roller profile. Therefore, the present work is undertaken to optimize roller profiles based on lubrication theory.
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Arash Arianpoor, Imad Taher Lamloom, Bita Moghaddampoor, Hameed Mohsin Khayoon and Ali Shakir Zaidan
The present study investigates the impact of managerial psychological characteristics on the supply chain management efficiency (SCME) of companies listed in Tehran Stock Exchange.
Abstract
Purpose
The present study investigates the impact of managerial psychological characteristics on the supply chain management efficiency (SCME) of companies listed in Tehran Stock Exchange.
Design/methodology/approach
To this aim, information about 215 companies was analyzed during 2014–2021. The sales per inventory ratio was used to calculate SCME. In the present study, the focus is on characteristics such as managerial entrenchment, managerial myopia, managerial overconfidence (MOC) and managerial narcissism, all considered as managerial attributes.
Findings
The present findings showed that managerial myopia/managerial entrenchment (MOC/managerial narcissism) have a negative (positive) effect on SCME. Hypothesis testing based on robustness checks confirmed these results. Moreover, the findings are presented separately for companies with high business strategy (first quarter) and low business strategy (third quarter). The results show that at low levels of differentiation strategy, managerial entrenchment does not have a significant effect on SCME while other managerial attributes have a significant effect on both high and low business strategy.
Originality/value
The present study contributes to the identification of managerial psychological characteristics influencing SCME to advance future studies and support practical efforts. The present findings can prove the significance of this research and fill the existing gap in research.
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The purpose of the paper is to analyse the characteristics, development and implementation of the Chinese labour arbitration system and its role in settling labour disputes.
Abstract
Purpose
The purpose of the paper is to analyse the characteristics, development and implementation of the Chinese labour arbitration system and its role in settling labour disputes.
Design/methodology/approach
The paper analyses official statistics and the arbitral cases published on the web sites of government labour and social security departments.
Findings
The paper finds that labour arbitration has become the most important mechanism for settling labour disputes in China since the middle 1990s. This trend indicates the fading of traditional political and administrative means due to the decreasing influence of governmental labour administration and the subordinate status of trade unions, and the emergence of the rule of law in setting labour terms. The effectiveness and fairness of labour arbitration is to a certain extent constrained by its limitations and workers' weak position in employment relations that prohibit it from fully upholding the Labour Law.
Research limitations
The paper shows that there is a paucity of literature devoted to labour arbitration in China. Further research is necessary to study labour arbitration, particularly the issues concerning: the frequency and reasons for workers to compromise in demands when claims, especially unfair dismissal cases; the process and the way in which arbitrators handle cases and make decisions; the fairness of arbitration awards; and the ways for improving competency and neutrality of arbitrators and arbitration committees.
Practical implications
The paper shows that the party‐appointed method is necessary to improve the two parties' control of arbitration process. The public should be allowed to access to case and arbitrator related information in order to increase the transparency of arbitration.
Originality/value
This is the first paper that introduces the labour arbitration system in China and analyzes its role in setting labour disputes and its potential for improvement.
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Liangwei Qiu, Xiaoyang Chen and Fakai Dong
This paper aims to experimentally investigate the film-forming capability of base oils containing poly-methacrylate (PMA) and poly-isobutene (PIB), in a point contact under pure…
Abstract
Purpose
This paper aims to experimentally investigate the film-forming capability of base oils containing poly-methacrylate (PMA) and poly-isobutene (PIB), in a point contact under pure rolling.
Design/methodology/approach
By using the relative light intensity method, the film thickness is calculated from the interferometer images which are captured by multiple-contact optical elastohydrodynamic lubricated test rig.
Findings
The test results reveal that polymers, both PMA and PIB, have a significant contribution to the film-forming capability of base oils and the film thickness increases with concentration. The forming-film capabilities for PMA and PIB in base oils are similar at low concentration, while PIB gives a higher film thickness than PMA at high concentration. Shear-thinning phenomenon are observed in all polymer-based oils.
Originality/value
The polymer usually as an additive is added into the low viscosity base oils to improve the properties of lubricant oil. This paper reports the lubricated properties of PMA and PIB with different concentrations in base oils and to evaluate their functional mechanism in a point contact.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-07-2020-0263/
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Yi Lin and Sifeng Liu
This paper seeks to investigate the roles of small and large projects in the development and evolution of a commercial company and why companies with a history of taking on large…
Abstract
Purpose
This paper seeks to investigate the roles of small and large projects in the development and evolution of a commercial company and why companies with a history of taking on large projects tend to eventually fail with large projects.
Design/methodology/approach
In terms of small and large projects, analytic models are established to: describe investors' behaviors; depict the dynamics between CEOs and their boards of directors; and reveal how profit ceilings exist for large projects.
Findings
After making the concepts of small and large projects precise, the paper establishes several analytic models for the investigation of the behaviors of various market participants. Then, it develops an explanation for why some decision makers like to take on large projects and why most new startups fail because of a lack of funds. A theory is given to show how investors value small projects more than large projects and why the current trend of moving manufacturing operations from industrialized nations to third world countries does not seem reversible in the foreseeable future, as long as international transportation costs stay low and the global economic system stays open and competitive. Among other results, it is also shown that: the higher the level the CEO's initial ability is, the more likely he would initiate and manage small projects, and the more labor effort he will devote to these projects; the CEO's additional effort spent on the small projects helps him gain non‐pecuniary benefits, which he can use to gain additional bargaining power over the board; to realistically maximize his private utility, the CEO would spend more of his time and effort on small projects; each large project has a glass ceiling for its maximum level of profits; companies taking on large projects cannot afford to devote much of their scarce resources to expand their market share and appearance; and to increase their profit potential, these companies have to control their spending so that their profit can be maximized by lowering their unit selling price ps; for small projects, the profit potential for the company is unlimited.
Originality/value
This work is the first to employ models of human behaviors to research the interactions and dynamics between projects of different scales. It provides a theoretically reliable distinction between small and large projects.
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Kanwal Jit Singh, Inderpreet Singh Ahuja and Jatinder Kapoor
This review paper reveals the literature on ultrasonic, chemical-assisted ultrasonic and rotary ultrasonic machining (USM) of glass material. The purpose of this review paper is…
Abstract
Purpose
This review paper reveals the literature on ultrasonic, chemical-assisted ultrasonic and rotary ultrasonic machining (USM) of glass material. The purpose of this review paper is to understand and describe the working principle, mechanism of material removal, experimental investigation, applications and influence of input parameters on machining characteristics. The literature reveals that the ultrasonic machines have been generally preferred for the glass and brittle work materials. Some other non-traditional machining processes may thermally damage the work surface. Through these USM, neither thermal effects nor residual stresses have been generated on the machined surface.
Design/methodology/approach
Various input parameters have the significant role in machine performance characteristics. For the optimization of output response, several input parameters have been critically investigated by the various researcher.
Findings
Some advance types of glasses such as polycarbonate bulletproof glass, acrylic heat-resistant glass and glass-clad polycarbonate bulletproof glass still need some further investigation because these materials have vast applications in automobile, aerospace and space industries.
Originality/value
Review paper will be beneficial for industrial application and the various young researcher. Paper reveals the detail literature review on traditional ultrasonic, chemical assisted ultrasonic and rotary USM of glass and glass composite materials.
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Ping Yang, Yawei Wang, T. Chang, H. Ma, Zhuyong Li, Zhijian Jin and Zhiyong Hong
The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current (DC…
Abstract
Purpose
The purpose of this paper is to propose a hybrid driving system that couples a motor and flywheel energy storage (FES) for a megawatt-scale superconducting direct current (DC) induction heater. Previous studies have proven that a superconducting DC induction heater has great advantages in relation to its energy efficiency and heating quality. In this heater, a motor rotates an aluminium billet in a DC magnetic field and the induced eddy current causes it to be heated. When the aluminium billet begins to rotate, a high peak load torque appears at a low rotation speed. Therefore, driving the billet economically has been a great challenge when designing the driving system, which is the focus of this paper.
Design/methodology/approach
A hybrid driving system based on FES is designed to provide extra torque when the peak load torque occurs at a low rotation speed, which allows the successful start-up of the aluminium billet and the operation of the motor at its rated capacity. The mechanical structure of this hybrid driving system is introduced. A simulation model was constructed using Matlab/Simulink and the dynamic start-up process is analysed. The influence of the flywheel’s inertia and required minimum engagement speed are investigated.
Findings
The results of this paper show that the hybrid driving system that couples FES and a motor can successfully be used to start the aluminium billet rotating. The flywheel’s inertia and engagement speed are the most important parameters. The inertia of the flywheel decreases with an increase in its engagement speed.
Practical implications
The cost of the driving system is significantly reduced, which is very important in relation to the commercial potential of this apparatus.
Originality/value
A novel start-up strategy for driving the aluminium billet of a superconducting DC induction heater at low speed is proposed based on FES.
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Kairong Shi, Zhijian Ruan, Zhengrong Jiang, Quanpan Lin and Long Wang
The purpose of this paper is to propose a new hybrid algorithm, named improved plant growth simulation algorithm and genetic hybrid algorithm (PGSA-GA), for solving structural…
Abstract
Purpose
The purpose of this paper is to propose a new hybrid algorithm, named improved plant growth simulation algorithm and genetic hybrid algorithm (PGSA-GA), for solving structural optimization problems.
Design/methodology/approach
PGSA-GA is based on PGSA and three improved strategies, namely, elitist strategy of morphactin concentration calculation, strategy of intelligent variable step size and strategy of initial growth point selection based on GA. After a detailed formulation and explanation of its implementation, PGSA-GA is verified using the examples of typical truss and single-layer lattice shell.
Findings
Improved PGSA-GA was implemented and optimization was carried out for two typical optimization problems; then, a comparison was made between the PGSA-GA and other methods. The results show that the method proposed in the paper has the advantages of high efficiency and rapid convergence, which enable it to be used for the optimization of various types of steel structures.
Originality/value
Through the examples of typical truss and single-layer lattice shell, it shows that the optimization efficiency and effect of PGSA-GA are better than those of other algorithms and methods, such as GA, secondary optimization method, etc. The results show that PGSA-GA is quite suitable for structural optimization.