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991.
992.
四辊轧机有载辊缝解析模型研究 总被引:1,自引:0,他引:1
针对轧制过程中轧辊的弹性变形和轧辊与轧件间的相互作用,通过对四辊轧机辊系变形和受力状况的分析,从理论上详细推导了直观的有载辊缝形状函数,明确了有载辊缝形状函数与相关因素的对应关系。同时,为了验证辊缝解析模型的准确性,采用该模型对某铝热连轧机的精轧末机架的出口板凸度进行了理论计算,并与在线测得数据进行比较,结果表明:该模型计算精度高,相对误差较小(低于15%)。该模型不但为板形的控制以及轧制板凸度的建模提供了理论基础,还为预报板形、研究板带截面上任一点的板凸度提供了方便。 相似文献
993.
MPS中速磨煤机磨辊磨损机理研究 总被引:1,自引:0,他引:1
在半工业性运行试验条件下,对MPS磨煤机磨辊的磨损机理进行了进一步模拟磨损试验。结果表明:尽管磨辊表面内外侧的磨损形貌特征存在较明显的差异,但其磨损机理却很相似,都为切削磨损、塑变疲劳磨损和脆性相断裂三种机制并存,且都以切削磨损为主,所不同的只是磨料对磨辊外侧区域的切削磨损作用远比对其内侧区域强烈,且切削方向也比内侧区域更加集中一致,这也正是磨辊在使用过程中内外侧磨损速率产生明显差异的根本原因。这种差异是由磨机本身的结构特点和运行特性所决定的。 相似文献
994.
Calculation of tool paths for a torus mill on free-form surfaces on five-axis machines with detection and elimination of interference 总被引:3,自引:1,他引:2
Dr Walter Rubio Pierre Lagarrigue Gilles Dessein François Pastor 《The International Journal of Advanced Manufacturing Technology》1998,14(1):13-20
Within the framework of a study carried out in cooperation with the Sapex Company, we sought to develop an overall machining program for free-form surfaces on a 5-axis NC machine tool. This program comprises a certain number of general cases that will then have to be adapted to specific situations. In this paper, we present the algorithms allowing the following cases to be dealt with:Positioning a torus mill at a given point on the surface with automatic search for interference between the end of the tool and the surface.Angular correction or the raising of the tool to avoid interference.Calculation of trajectories for a rolling torus mill on a ruled surface resting on a free-form surface of the NURBS (Non Uniform Rational B-Splines) type.The latter can be broken down into two parts:Seeking the axis position on the adjusted surface.Determination of the tool's point of contact on the freeform surface. 相似文献
995.
The present investigation aims to represent three-dimensional motion and breakage phenomena of black pepper seeds in the cryogenic mill (hammer mill) using discrete element method (DEM). In DEM modeling, bonded particle model was coupled with Hertz-Mindlin contact model. Calibration method was used to select appropriate model (bond) parameters. The calibrated set of bond parameters includes 3.12?×?1011?Pa?m?1 normal stiffness; 1.56?×?1011?Pa?m?1 shear stiffness; 3.88?×?108?Pa critical normal stiffness; 1.94?×?108?Pa critical shear stiffness. Besides, the validity of calibrated parameters was tested in the hammer mill. The observed qualitative and quantitative results (breakage and flow pattern) of numerical and experimental approaches were in good agreement. Based on these results, a few prefatory suggestions were provided to improve the design aspects of the mill. Overall, DEM modeling offered a better understanding of particle breakage and flow pattern in the mill. 相似文献
996.
This paper investigates the grindability of calcite powder (D50 = 6.68 µm) to submicron particle sizes using stirred media mill (0.75 l) and ultrasonic generator (400 W, 24 kHz). The present study focuses directly on the comminution of calcite powder in water media by combined stirred milling and ultrasonic treatment and effects of some operational parameters such as grinding time (10–30 min), ultrasonic power (40–100% µm as amplitude settings), and solid ratio (10–30% w/w) on comminution. Experimental results have been evaluated on the basis of product size and width of particle size distribution. 相似文献
997.
Kazuaki Kanai Yoshifumi Fukui Takahiro Kozawa Akira Kondo Makio Naito 《Advanced Powder Technology》2017,28(1):50-54
Here, we report on the effect of BaF2 powder addition on the mechanical synthesis of Ce3+-doped Y3Al5O12 (Y2.97Al5O12:Ce0.033+, YAG:Ce3+) phosphors for white light emitting diodes. The YAG phosphors were synthesized by the mechanical method using an attrition-type mill. When BaF2 was added at 6 wt% to the raw powder materials and milled, the synthesis of YAG:Ce3+ was favorably achieved at the vessel temperature of 255 °C, which was about 1200 °C lower than the YAG phosphor synthesis temperature by solid-state reaction. The synthesized YAG:Ce3+ phosphor revealed the maximum internal quantum yield of 57%. 相似文献
998.
《Advanced Powder Technology》2020,31(5):1957-1962
In recent years, significant research has been focused on the development of carbon nanotube (CNT) reinforced aluminum nanocomposites, which are quickly emerging because of their lightweight, high strength and other mechanical properties. The potential applications of these composites include the automotive and aerospace industries. In this study, powder metallurgy techniques are employed to fabricate aluminum (Al)/CNT nanocomposites with different raw material properties with optimized conditions. We successfully fabricated three different samples, including un-milled Al, un-milled Al with CNT and milled Al with CNT nanocomposites, in the presence of additional CNTs with various experimental conditions using a planetary ball mill. Scanning electron microscopy and field emission scanning electron microscopy are used to evaluate the particle morphology and CNT dispersion. The CNTs are well dispersed on the surface of the fabricated milled Al with CNT nanocomposites than un-milled Al with CNT nanocomposites for milling. The fabricated Al/CNT nanocomposites are processed by a compacting, sintering and rolling process. Vickers hardness measurements are used to characterize the mechanical properties. The hardness of the Al/CNT nanocomposites are improved milled Al with CNT nanocomposite compared other fabricated composites. 相似文献
999.
Fine grinding in stirred media mills is an important process in mineral, chemical and pharmaceutical industry. The stressing mechanism in these mills is grinding through compression and shearing by grinding beads. A few studies have examined grinding bead transport in stirred media mills. Radiometric methods detect the local filling degree, but little is known about the experimental motion of the grinding beads in the mill. This study aims to investigate the position, velocity and radial circulation of individual grinding beads at different operation parameters (viscosity and tip speed) by a fast and inexpensive measurement technique. Additional information about stresses in the mill were derived, such as a relation between axial grinding media distribution and grinding bead velocity. As a result, the two investigated operation parameter (viscosity and tip speed) effect the grinding bead velocity and grinding bead transport in the mill. The mentioned results can be used to validate DEM simulation results. 相似文献
1000.
Cutting forces modeling is the basic to understand the cutting process, which should be kept in minimum to reduce tool deflection, vibration, tool wear and optimize the process parameters in order to obtain a high quality product within minimum machining time. In this paper a statistical model has been developed to predict cutting force in terms of geometrical parameters such as rake angle, nose radius of cutting tool and machining parameters such as cutting speed, cutting feed and axial depth of cut. Response surface methodology experimental design was employed for conducting experiments. The work piece material is Aluminum (Al 7075-T6) and the tool used is high speed steel end mill cutter with different tool geometry. The cutting forces are measured using three axis milling tool dynamometer. The second order mathematical model in terms of machining parameters is developed for predicting cutting forces. The adequacy of the model is checked by employing ANOVA. The direct effect of the process parameter with cutting forces are analyzed, which helps to select process parameter in order to keep cutting forces minimum, which ensures the stability of end milling process. The study observed that feed rate has the highest statistical and physical influence on cutting force. 相似文献