Advanced Materials Research Vols. 129-131

Abstract: In order to know whether the ICT rotary detecting table can achieve its work requests, performance and structure characteristics of ICT scanning worktable are analyzed. In view of the rotary detecting table turning motion, the method of finite element is used to do dynamic analysis. According to the structure and working features of the rotary detecting table, it is modeled. Then, in terms of the actual operating mode, the model is done the analysis of modal and transient dynamic. The deformation curve figures and dynamic response curve figures are received. By deformation analysis and stress analysis, the dynamic performance of this structure meets design requirements.

Abstract: Tamper mechanism is one of the most important parts in all of Asphalt-pavers. In this article, the mathematical model of the tamper system has been established and the stability of the system has been analyzed by using Matlab. According to the operating principle of tamper system of Asphalt-paver, the simulation model of tamper system of Asphalt-paver has been established by using AMESim. The main parameters of the model were set, and then, the simulation results were analyzed, which show that the system is stable and the dynamic performance of system will be improved, when accumulator and PID controller were equipped. Besides, the tamping frequency of hammer is very important to the performance of system. When tamping frequency of hammer over 20HZ, the performance of system will go bad.

Abstract: Lubricating characteristics of sector cavity multi-pad hydrostatic thrust bearing are affected significantly by velocity, poor design can cause lubricant film rupture and dry friction, even leading to failure of hydrostatic bearing tribology. For this problem, the Computational Fluid Dynamics and the lubrication theory have been used to analyze velocity characteristics of the parameters such as cavity pressure of oil, oil cavity flow and film thickness, to gain relationship between velocity and lubricating properties of sector cavity multi-pad hydrostatic thrust bearing, avoiding the occurrence of hydrostatic bearing tribological failure. It is shown that along with the speed of the worktable increasing, the flow of lubricant oil caused by inertia and centrifugal force become larger, the flow of efflux from the oil cavity also become larger, causing the pressure drop of the oil cavity, the thinning of the film thickness, the occurrence of film rupture and dry friction and failure of hydrostatic bearing tribology. The study provides the basic data for the hydrostatic thrust bearing design, the lubrication and the experiment, implements of the prediction of the hydrostatic thrust bearing lubrication velocity characteristics, and reaches the purpose of reducing economic loss.

Abstract: Plasma beam is currently advisable and advantageous in surface modification for several reasons; for instants, high energy, portability and low cost. In this study, plasma beam was employed to deposit pre-paste, and also used for surface quenching. The results are shown that a uniformed harden layer free of crack and porosities with a thickness of 1.8-2.2mm can be produced by both two methods. After plasma beam alloying, the overlayer with obvious two interfaces can achieve a maximum hardness of 1100HV0.2. This improvement is the mainly contribution not only by land-like TiC reinforced particles and Fe2.5Ti0.5O4, a product of reaction between the pre-paste and molten matrix, with dispersive distribution at the surface, but also alloying elements enriched at the top of molten pool. The experiment suggested that the hardness of the surface was also highly affected by the parameters of plasma beam process alloying; namely, the higher velocity plasma beam moves and the more TiC particles contained, the higher hardness can be obtained. In contrast with the former process, after plasma surface quenching, the overlayer with one interface has a maximum hardness of 600HV0.2.

Abstract: The aim of this paper is to investigate the effects of HIP treatment on 440C-TiC composite steel. In this study, AISI 440C stainless steel powders were added with different amounts of TiC powders (25, 33 and 40 wt%), the composite materials were sintered at 1473 K, 1573 K, and 1673 K, followed by different pressures of HIP and HIP plus heat treatment. HIP treatments were used 120 and 150 MPa at 1523 K 1 hour. Experimental results showed that the microstructure of matrix had small needle structures after HIP treatment, which were effective in improving the hardness and strength. Furthermore 440C-TiC composite steels which were added with 25wt% TiC powder after 1673 K sintered and high pressure HIP treatments, TiC powders were uniformly dispersed in the high chromium stainless steel matrix were observed and consequently possessed the higher hardness (HRA 85) and highest TRS (1213 MPa).

Abstract: Hydrostatic center rack is an open type hydrostatic supporting equipment. In this paper, taking oil film of middle pillow of hydrostatic center rack as the research object, the velocity field, pressure field and dynamic pressure effect are simulated based on CFX finite element analysis software. The velocity distribution, pressure field and the relationship curve between spindle speeds and dynamic pressure are obtained. The simulation results show that there is negative pressure at the entrance of spindle rotation direction. When the spindle speed is less than 360r/min, the dynamic pressure effect is not obvious and at the steady state basically. Above this speed, the dynamic pressure effect increases significantly as the spindle speed rises. The simulation results can reflect the flow law of internal flow field of the middle pillow. It provides a theoretical basis for the structure optimization of hydrostatic center rack and open type radial sliding bearing in engineering practice.

Abstract: Inspired from the serious plastic deformation of some gears with heavy power transmission in practical usage in metallurgical industry, we believe that there must existed some kind of gear profile which is most suitable in both the contact and bending fatigue strength. The aim of this paper is intention to produce a gearing of these properties. From careful analysis and deep going investigation, we think that it is the profile of equal conjugate curvature with high order of contact, and analyzed the forming principle of this kind profile in mathematic method. The contact stress is so low that even the Hertz theory, with which the contact stress can be calculated for most of gearing, is invalid. This paper researched how to realize this kind of gearing.

Abstract: Physical simulation was conducted on the process of upsetting cylinder between flat platens by using colorful plasticine. The results of the physical simulation are basically consistent with rigid-plastic finite element analysis, which supports the rigid-plastic mechanical model for the cylindrical billets whose height-diameter ratio are greater than 1. Further physical simulation is conducted on cylinders upsetting between platen and supporting ring. The experimental method provides a reference for physical simulation of large deformation.

Abstract: The metallic magnesium by siliconthermic reducing method was studied by magnetite as raw materials. The Mg reduction rate, such as reduction temperature and time, Si-Fe added mount, mineralize CaF2 added, briquette pressure, were discussed by experiments. Through siliconthermic reducing process analyzed, the result showed reduction process was in line with three-dimensional phase boundary reaction D3 model and kinetic equitation were expressed as , with an apparent activation energy 313.58 KJ/mol, frequency factor 2.7×106 s-1.

Abstract: The flexural fatigue experiment of plain concrete (C) and Steel - Polypropylene Hybrid Fiber Reinforced Concrete (HFRC) is carried out to study the flexural fatigue performance and damage laws under cyclic loading. With the strain gauges pasted on the bottom of the specimens, the strain is collected by dynamic acquisition instrument.We obtain the fatigue life and the maximum strain - cyclic ratio ( ) curves by counting and analyzing the results of fatigue experiment ,which move forward a single step for analysis of fatigue damage laws of HFRC. The study would provide reference for flexural fatigue properties of HFRC.