Papers by Author: Yong Tang Li

Abstract: The numerically simulation of temperature field was carried out by the ANSYS software in multi-layer powder-feeding laser cladding forming.3-D finite element model was found, which nonlinear characteristics of the material thermal properties and the boundary conditions of the convective transfer heat was considered; The process of powder falling into the substrate and cladding element growing was accomplished by “Element Birth and Death technology” in the process of numerical simulation. The result shown that the primarily solidified cladding layer to the following cladding layer has a preheating function in the process of multi-layer laser cladding forming, the initial temperature of following cladding layer is higher than primarily melted cladding layer; The thermal cycling curves of the molten pool nodes takes on periodic variation and basic similar in every layer cladding; The end effect problem is apt to happen in cladding layer, which the phenomenon of edge collapsing or partially burnt is formed; The temperature gradient distribution is divided into two parts, the temperature gradient level distribution along the laser scanning direction in the top and perpendicular distribution in the bottom, The temperature gradient appearances mutation and maximum value in the junction of the substrate and cladding layer, which the crack is apt to be caused in this region.

Abstract: In this paper, the first 80MN rapid forging hydraulic press in China was developed. The inclined double-column and pre-stress combined frame structure and the direct Pump-driven technologies were adopted for the first time in the design of this press. The linkage driving with the full-hydraulic orbital manipulator has been realized. A rapid forging frequency of 75~80 /min and a finishing precision of ±1mm for hot-state forgings can be obtained. The three dimensional full-contact solid model of the double-column combined frame structure of the 80 MN rapid forging hydraulic press has been set up. The modal analysis of the pre-tightened frame has been carried out with the FEM analysis software ANSYS. The first five-order inherent frequencies and the corresponding natural modes have been obtained, the mode shapes of various orders have also been analyzed in detail. It is shown from the research results that the inherent frequency of the frame is larger than the impact frequency. Therefore, resonant vibration of the structure will not occur. The analysis results will have an important significance for the understanding of the dynamic performance of the rapid forging hydraulic press, optimization of the structure design of the press and the decrease of vibration and noise pollution.

Abstract: The CCT curve and TTT curve of as-cast 42CrMo steel were precisely simulated by using JmatPro software. The quenching process(which is as follow: quenching at 860°C by AQ251 quenching liquid and cooling to 200°C) was given by analysizing the CCT curve. The quenching microstructure, hot-stress field and hardness after quenching were simulated by using the Deform-HT module The results were obtained as follows:(1)The microstructure of the materials is martensite+bottom bainite at the surface and pearlite+ferrite at the centure.(2)The surface hardness and central hardness were separately 51.3 and 28.5 HRC. The metallographic observation and hardness experiment were done and the results of numerical simulation was finally verified.

Abstract: Traditional network control systems require designers to use the serial interface or the bus as tools to control equipments. These ways lead to complicated circuit connection and unreliability of hardware. It is therefore imperative to have good methods to explore a more suitable design choice, which can avoid the problems mentioned above as more as possible. This paper presents a TD-SCDMA network control system based on rapid prototyping equipment in VC++ 2008. It also provides high-level modelling, programming methods and running results for this system in terms of software and hardware. More specifically, this system takes advantage of network control technology, TD-SCDMA network technology and advanced manufacturing technology. Wireless communication and control are accomplished timely and accurately between the network control centre and a number of controlled equipments by use of Winsock control in TD-SCDMA network. This system also can manage the historical data by using database. Furthermore, it has such advantages as low cost and easy to maintain and promote.

Abstract: Cold rolling precision forming process of spline is one of the high-efficiency, precision and non-chip forming advanced manufacturing technologies. It has the characteristics such as high forming efficiency, energy-saving, low material consumption and better forming properties of components. The principle and the force of involute spline cold rolling precision forming process were analyzed. Forming experiments of involute spline cold rolling were carried out, and the microhardness map of the tooth outline was gained. The rule of the metal flow in the deforming area and the forming mechanics of the microstructure were analyzed. The influence of plastic deformation on the forming properties was also conducted. Experimental results showed that dramatic plastic deformation has taken place on the upper surface of the workpiece during the cold rolling process of spline, while the influence on the inner materials were very small. The grains were distributed as a flow line pattern along the tooth profile, and the grains in the plastic deformation zone presented a fine and long fibrous state. The hardness on the section of the tooth outline is regularly distributed. Compared with the spline components obtained from conventional cutting method, the hardness of the spline was greatly increased, therefore, comprehensive mechanical property such as wear resistance and impact resistance were largely improved. Precision measuring and hardness testing of the tooth outline section showed that the components obtained by the experiments were free of defects, and the application requirement can be satisfied.