Study on the influencing factors of the deformation in the process of gear shaping

Ring gear is an important part of high-power transmission system. Because of its thin wall and low stiffness, it is easy to produce deformation in the process of gear shaping, which affects its accuracy. In order to ensure the machining quality of gear shaper, this research focuses on the typical material 42CrMo, which is used in the gear ring of automobile gearbox. Through the finite element simulation and actual test, the influence of gear shaper cutting parameters on the deformation of gear ring is studied. The results show that the influence of the main cutting parameters on the deformation of the ring gear is in the order of radial feed, circumferential feed, stroke speed and cutting depth. In the actual gear shaping process, the cutting parameters can be adjusted according to the deformation law of 42CrMo workpiece in the gear shaping process, so as to control the deformation of gear ring.

Global experience of HVDC composite insulators in outdoor and indoor environment

High-voltage direct current (HVDC) transmission is known as green-energy transfer technology and has recently become an attractive alternative of high-voltage alternating current (HVAC) due to its high-power transmission capability and lower power loss. Use of composite insulators on direct current (DC) transmission lines experienced rapid growth in recent years due to their high hydrophobicity and better performance in contaminated environment than conventional ceramic insulators. During their service operation on DC lines, insulators are prone to more accumulation of contaminants due to unidirectional electric field. The contaminants under wet conditions allow leakage current to flow on the insulator surface. Being organic in nature, polymeric insulators have a tendency to age under the combined effects of electrical and environmental stresses. To fully understand the long-term aging performance of DC composite insulators, a detailed survey was considered necessary. Towards that end, this paper critically summarizes worldwide experience of aging performance of composite insulators in the field as well as in laboratory conditions.

Determination of the Operating Temperature of the Gas-Insulated Transmission Line

Gas-insulated lines (GILs) have been increasingly used as high-current busducts for high-power transmission. Temperature is one of the most important factors affecting the performance and ampacity of GILs. In this paper, an analytical method was proposed to determine the temperature of a three-phase high-current busduct in the form of a single pole GIL. First, power losses in the phase conductors and enclosures were determined analytically with the skin, and proximity effects were taken into account. The determined power losses were used as heat sources in thermal analysis. Considering the natural convection and radiation heat transfer effects, the heat balance equations on the surface of the phase conductors and the screens were established, respectively. Subsequently, the temperature of the phase conductors and the enclosures were determined. The validation of the proposed method was carried out using the finite element method and laboratory measurements.