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四辊轧机辊系偏移距机理的不确定性和微尺度静定性 总被引:1,自引:0,他引:1
生产板带的四辊轧机辊系,普遍设置偏移距求得轧辊间平行定位及其稳定以防止辊间交叉,成为四辊轧机辊系平行定位机理编入轧机教科书及参考书中。近代相继出现的现代四辊轧机辊系都设置偏移距,但未能保证其机理的确定性,辊间动态交叉现象的发生屡禁不止,引发超大轴向力损坏推力滚动轴承或生成轧制支反力偏差破坏板形控制的稳定性。设置偏移距3mm的高速铝箔四辊轧机轴向力在线检测试验,揭示轧制过程中工作辊与支承辊之间发生规律性动态交叉现象。轧制中轧辊之间的动态交叉行为,与轴承座和机架窗口立柱间微小间隙大小相对应,只限于轧机的交叉角β≤0.05°区间,远小于交叉(Paircross,PC)轧机的交叉角(β=1°~1.5°),但派生的轴向力超出额定值的3倍以上。四辊轧机模拟辊系偏移距静态零调试验,探明轧辊间初始安装位置不变没有轧辊的水平位移。辊间动态交叉现象和静态水平位移为零的两种结果,揭示出设置偏移距机理的不确定性,不能用于四辊轧机辊系平行定位及稳定性设计。 相似文献
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介绍一种新型冷轧板带轧机工作辊轴承座的结构设计,此设计可得到较大的传动轴直径,整体装卸工作辊轴承座,减少安装时间,提高轧机的生产效率。 相似文献
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分析辊系更换现状,查找影响辊系更换效率的因素,通过系统性优化辊系更换方案,提升辊系更换效率,大幅缩短换辊时间。 相似文献
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介绍一种新型冷轧板带轧机工作辊轴承座的结核设计,此设计可得至较大的传动轴直径。整体装卸工作辊轴承座,减少安装时间,提高轧机的生效率。 相似文献
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设计了磨粉机快辊轴承座的加工工艺和具体的工装夹具.利用卧式加工中心加工磨粉机快辊轴承座,辅以能够高效快速夹紧的夹具,既可以保证加工精度,又能够提高加工效率. 相似文献
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介绍了如何利用计算机对于形状复杂和高精度的凸轮进行辅助设计,以及将设计结果直接在数控机床上加工的方法,分析了图解法设计的局限性和计算机辅助设计的优越性,指出了利用计算机辅助解析法设计是实现数控加工的基础,也是未来机械设计的发展方向。 相似文献
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Dr Amy J. C. Trappey C. Richard Liu 《The International Journal of Advanced Manufacturing Technology》1993,8(5):297-304
The geometric and topological specification of a workpiece boundary is usually represented in a specific data format in a CAD database. To retrieve a set of workpiece data, to analyse its shape in addition to the machining requirements, and to determine the proper fixture configuration accordingly, are not trivial tasks when a part has a complicated shape. The real challenge is to recognise and synthesise the shape of a workpiece from its data representation. Consequently, the decision for fixturing can be made when the shape of a workpiece and the relationship of the shape and the fixturing configuration can be derived by a systematic methodology. In this paper, a projective spatial occupancy enumeration (PSOE) approach is applied as a representational and manipulating scheme for developing algorithms in automatic fixture configuration. The workpiece is projected onto the working plane of the fixture baseplate. A 2D projection is defined as a matrix of cells which can represent a workpiece with an arbitrary shape. Using a discrete search based upon the matrix of cells, the fixture types and their locations are generated according to a set of heuristic algorithms. This work is a generalisation and extension of previous works for prismatic parts. The same methodology is equally applicable in general robot grasping. 相似文献
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Hongbo Lan Yucheng Ding Jun Hong Bingheng Lu 《The International Journal of Advanced Manufacturing Technology》2008,37(3-4):341-353
This paper presents a novel reverse engineering digitizing system for full part geometry, which is based on a cross-sectional
imaging device built in a NC milling machine. The system successively captures a picture for each planar cross-section contour
of the part by end-milling and CCD imaging, and builds the geometry for both external and internal surfaces of the complex
3D part based on a set of the vectored cross-sectional contours. The system mainly consists of three components: a NC milling
machine, a cross-sectional imaging device and a computer control unit. Some issues involving the principle and process flow
of the system, encasing materials, cross-sectional imaging and NC code generation, etc. are described in detail. Built on
an existing NC milling machine, a portable device for capturing the cross-sectional images is designed, which includes an
isolated light source, a digital camera, a protective case, a rigid arm and a robust tripod. The device, connected to a computer
control unit, serves as a highly flexible accessory for the NC milling machine, constructing the cross-sectional imaging system
for reverse engineering. Furthermore, the error analysis and accuracy assessment of the system are also addressed. A typical
case is discussed in detail to illustrate the applications of the system. Such a re-configurable digitizing system for reverse
engineering offers a number of advantages, such as the functional extension of an existing NC milling machine, low costs,
and rapid construction. As a result, this system provides a feasible and useful scheme for many enterprises to construct their
own reverse measuring system based on existing equipment to aid in rapid product development and extend the function of existing
equipment. 相似文献
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A method for local measurement of air leakage rate is presented that can be used to accurately and quickly assess leakage rates across a surface, such as around a valve or hatch in a pressurized gas tank or a window in a building. The method uses a small local enclosure with constant volume placed about a region on the structure under investigation (e.g., a window), which is depressurized and injected with a small concentration of carbon dioxide as a tracer gas. The time variation of the pressure and carbon dioxide concentration inside the enclosure are monitored and used to quantify the leakage flow rate as a function of pressure difference. This method uses a small enclosure with internal mixing so that a quasi-steady-state condition is quickly achieved. Because of the small size of the enclosure, advanced data processing techniques are necessary to reduce uncertainty in determination of the rate of change of the carbon dioxide concentration that arises from sensor variability. Results of a laboratory demonstration of the proposed leakage detection and characterization device are reported for the problem of leakage through a circular hole in a plate with prescribed pressure differences. Experimental results from the laboratory tests are found to be in excellent agreement with results of a numerical simulation of leakage flow through a hole, as well as predictions from a number of empirical equations for this problem found in the literature. 相似文献
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F. L. Chen Y. M. Chiang 《The International Journal of Advanced Manufacturing Technology》1999,15(4):261-267
This study presents a novel mathematical method for resolving the accessibility of a through slot when using coordinate measuring
machines. The proposed method considers the actual shape of a probe consisting of a motor column, a stylus, and a probe tip.
Also derived herein is a mathematical method to derive the feasible probe orientation of the measurement point in the bottom
of a slot using a geometrical relationship between the probe and the slot. 相似文献
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为了在微尺度范围内实现对目标对象进行柔性施力、推拉等一系列微纳操作,提出一种通过生成控制单个微尺度气泡直接与目标对象进行微纳操作的方法。当用气泡作为执行器对目标对象施力时,由于气体的可压缩性,气泡会被挤压变形,实现了柔性施力的过程。首先通过毛细管连接气泵的方式在液体环境下生成单个微尺度气泡,并定性分析气压法生成控制气泡变化的过程;随后,为了验证气泡可以作为执行器对研究对象进行施力,实验以一个微型悬臂梁作为参照物,气泡作为执行器对悬臂梁的末端施力,通过悬臂梁的形变来估算气泡的施力值。对实验数据进行分析,得出气泡作为执行器特性以及气泡的形变与其输出力之间的线性关系。 相似文献
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Jeong-Hyun Sohn Wan-Suk Yoo Keum-Shik Hong Kwang-Suk Kim 《Journal of Mechanical Science and Technology》2002,16(6):810-818
When the contribution of lightweight components to the total energy of a system is small, the inertia effects are sometimes
ignored by replacing them to massless links. For example, a revolute-spherical massless link generates two kinematic constraint
equations between adjacent bodies and allows four relative degrees of freedom. In this paper, to implement a massless link
systematically in a computer program using the velocity transformation technique, the velocity transformation matrix of massless
links is derived and numerically implemented. The velocity transformation matrix for a revolute-spherical massless link and
a revolute-universal massless link are appeared as a 6X4 matrix and a 6X3 matrix, respectively. A massless link model in a
suspension composite joint transmitting external forces is also developed and the numerical efficiency of the proposed model
is compared to a conventional multibody model. For a massless link transmitting external forces, forces acting on links are
resolved and transmitted to the attached points with a quasi-static assumption. Numerical examples are presented to verify
the formulation. 相似文献
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This paper presents a new concept of scene recognition by a genetic algorithm (GA), using the 2-D gray-scale image of a working space, termed here as raw-image, and a model shaping the 2-D top-surface of a target object. In fact here, the problem of object recognition in the raw-image is changed into an optimization problem of a model-based evaluation function. We make use in this research of a GA, as a search and optimization method. This GA employs a model-based fitness function as its objective function to perform the search of a target in the raw-image. In this research, three object models, namely a frame model, a surface model, and a surface-strips model are investigated in order to determine which one is the best for scene recognition in a noisy environment. Also, in order to appraise the recognition performance of each model, a comparative study is performed by analyzing the answers to the following criteria questions: sensitivity, reliability, and speed. The effectiveness of the method has been verified through experiments using real-world raw-images, and the method has shown its robustness of object recognition with the surface-strips model, in spite of the noises in the scene. 相似文献