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Evaluation of MQCL Technique Using MoS2 Nanofluids During Hard Milling Process of SKD 11 Tool Steel
Tran Minh Duc,
Pham Quang Dong,
Tran The Long,
Dang Van Thanh
Issue:
Volume 7, Issue 4, August 2019
Pages:
91-100
Received:
24 May 2019
Accepted:
5 August 2019
Published:
23 August 2019
Abstract: The current study demonstrates the effect of minimum quantity cooling lubrication (MQCL) using MoS2 emulsion-based nanofluid on hard milling of SKD tool steel (52-60 HRC) with coated cemented carbide inserts. The input machining parameters including nanoparticle concentration, cutting speed and hardness on cutting forces are investigated in term of cutting force components by using ANOVA analysis applied for the Box-Behnken experimental design. The results indicate that the hardness and nanoparticle concentration have a strongest influence on cutting forces. The interaction effects of investigated parameters are studied in detail and provide the important direction for using MoS2 nanofluid efficiently with the proper concentration of 1.0-1.1 wt%. Moreover, the cutting performance of carbide tools is significant improved during hard milling process due to the better cooling and lubricating effects of MQCL technique.
Abstract: The current study demonstrates the effect of minimum quantity cooling lubrication (MQCL) using MoS2 emulsion-based nanofluid on hard milling of SKD tool steel (52-60 HRC) with coated cemented carbide inserts. The input machining parameters including nanoparticle concentration, cutting speed and hardness on cutting forces are investigated in term of...
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Influence of Different Heat Input on Submerged Arc Welded Joints of High Strength Low Alloy Steel SX780CF
Houyi Li,
Xiansheng Hu,
Zhixiang Peng,
Youlong Zhou
Issue:
Volume 7, Issue 4, August 2019
Pages:
101-105
Received:
14 July 2019
Accepted:
15 August 2019
Published:
3 September 2019
Abstract: SX780CF is a new type domestic high strength low alloy (HSLA) steel with tensile strength of 800 MPa, which was used firstly for pressure pipes in the hydropower unit. In order to improve the efficiency, SX780CF is generally welded by submerged arc welding (SAW), and a kind of special intelligent welding machine for large-scale pressure steel pipe was adopted, which can realize intelligent mechanized grouping and automatic welding in tunnel. In this paper, two different levels of heat input were used to weld SX780CF. The weldability of two joints was analyzed, the mechanical properties of the joints were measured, and the hardness distribution of the joints was tested. Meanwhile, the microstructure was observed. The results show that the properties of these joints welded by two different levels of heat input could satisfy the demand of the GB 50766 -2012 standard. The mechanical properties of the weld joint with larger heat input were slightly higher than those with smaller heat input. The hardened tendency of SX780CF is small, however, the steel with the thickness of 60 mm needs to be preheated at more than 112°C. Comprehensive comparison shows that the submerged arc welding method with larger heat input has better efficiency and cost advantage, and it is worthy of promotion in hydropower project.
Abstract: SX780CF is a new type domestic high strength low alloy (HSLA) steel with tensile strength of 800 MPa, which was used firstly for pressure pipes in the hydropower unit. In order to improve the efficiency, SX780CF is generally welded by submerged arc welding (SAW), and a kind of special intelligent welding machine for large-scale pressure steel pipe ...
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Design and Application of Insulator Detection Robot System for UHVDC Transmission Line
Xueneng Huang,
Yuwen Xie,
Chongjie Ma,
Jinpeng Tan,
Dongfeng Qiu,
Youneng Wu,
Su Fang,
Yitao Lu,
Yongjian Lin,
Xianning Li
Issue:
Volume 7, Issue 4, August 2019
Pages:
106-110
Received:
15 June 2019
Accepted:
16 August 2019
Published:
4 September 2019
Abstract: In recent years, with the vigorous construction of the ultra-high voltage grid, the line operating voltage level has become higher and higher. In order to ensure the safe operation of the transmission line, the line insulator string has a length of several tens of meters, and traditional manual testing has been unable to meet the requirements. With the continuous maturity of wireless communication technology, electromagnetic compatibility technology, sensor technology and other comprehensive technologies, it is necessary to develop an insulator string detection robot to replace artificial insulator detection work on UHV transmission lines. By means of wireless sensor communication technology, electromagnetic compatibility technology, video image technology and many other technologies, the insulator detection robot designed in this paper has realized automatic detection of zero resistance value of insulator of UHV transmission line. In addition, the real-time monitoring of insulator resistance value can be carried out through wireless communication to achieve the purpose of timely alarm. In addition, the robot's motion status and the insulator's field status can be observed in real time through video image acquisition. The insulator detection robot designed in this paper realizes the automatic detection of the zero value of insulator of the UHV DC transmission line. It can adapt to the UHV AC DC transmission line with different voltage levels by changing the length of the climbing arm, and at the same time adapt to the climbing detection of the string insulator of tension tower and the vertical insulator of the straight tower. The problem that the insulator string of the UHVDC transmission line can not be automatically detected by electric charge has been solved. It greatly improves the efficiency of insulator detection and the automation level of power transportation maintenance, reduces the cost of human transportation, and creates higher economic and social benefits.
Abstract: In recent years, with the vigorous construction of the ultra-high voltage grid, the line operating voltage level has become higher and higher. In order to ensure the safe operation of the transmission line, the line insulator string has a length of several tens of meters, and traditional manual testing has been unable to meet the requirements. With...
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Design of Self-restriction Hydrostatic Thrust Spherical Bearing (Fitted Type)
Ahmad Waguih Yacout Elescandarany
Issue:
Volume 7, Issue 4, August 2019
Pages:
111-122
Received:
14 August 2019
Accepted:
4 September 2019
Published:
20 September 2019
Abstract: This is the last part of the series studying the fitted hydrostatic thrust spherical bearing. It handles an unconventional design of this type of bearings. The conception of this design is to break the rules controlling the bearing restrictions, where it is believed that without restrictors no hydrostatic bearing could be got (axiom). The paper focused the effort to derive a general characteristic equation that can control the design in turn the bearing performance and behavior. This general characteristic equation, through its simple form, gives the designer the ability to get a comprehensive conception about his problem and widely opens the door in front of him to design a conventional or unconventional bearing whatever the bearing purpose. The effective parameters; needed to be known for designing the bearing; were concentrated into three items; the rotor speed, the seat dimensions and the lubricant properties. The characteristic equation shows that the seat radius and the inlet angle play the major role in determining the supply pressure, in turn the load carrying capacity. The inertia, the recess angle and the lubricant viscosity have the major effect on determining the bearing stiffness in case of the partial hemispherical seats while in case of the hemispherical seats the stiffness has slightly been affected. The design shows that the bearings with hemispherical seats have extremely low stiffness, practically zero stiffness and very high temperature rise, which make this bearing configuration invalid to be self restriction bearing; while the bearings with partial hemispherical seats have a very wide stiffness range allowing the designer to control and design the bearing with the stiffness needed for any purpose (from zero stiffness to extremely high stiffness). The lubricant temperature rises about three degrees centigrade which practically means that the bearing operates at constant temperature.
Abstract: This is the last part of the series studying the fitted hydrostatic thrust spherical bearing. It handles an unconventional design of this type of bearings. The conception of this design is to break the rules controlling the bearing restrictions, where it is believed that without restrictors no hydrostatic bearing could be got (axiom). The paper foc...
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