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Discussion on advanced manufacturing
WANG Xiankui
Front. Mech. Eng.. 2007, 2 (3): 251-262.
https://doi.org/10.1007/s11465-007-0044-4
Advanced manufacturing consists of continuity of manufacturing, its broad sense, and the core of the manufacturing process. The technology of continuous manufacturing is discussed according to both historical and modern perspectives. The relationship between human development and manufacturing technology is also discussed. Manufacturing is a continuously evolving topic. It is not only the foundation and means of imagination, conception, the science, and the technology of material change, but also the expression of national economy, national defense, and the support industries. The broad sense of manufacturing theory, which extends the concept of manufacturing, is an important development in the 20th century. The sense is analyzed in connection with design, material forming theory, synthesis of manufacturing technology, manufacturing modes, life cycle of product, hardware and software, and support environment, etc. At the same time, the core action and the development of the theory and technology of process is also discussed. At the end of this paper, the development directions of mechanical manufacturing science and technology are mentioned.
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New method for computer numerical control machine tool calibration: Relay method
LIU Huanlao, SHI Hanming, LI Bin, ZHOU Huichen
Front. Mech. Eng.. 2007, 2 (3): 301-304.
https://doi.org/10.1007/s11465-007-0053-3
Relay measurement method, which uses the kilogram-meter (KGM) measurement system to identify volumetric errors on the planes of computer numerical control (CNC) machine tools, is verified through experimental tests. During the process, all position errors on the entire plane table are measured by the equipment, which is limited to a small field. All errors are obtained first by measuring the error of the basic position near the original point. On the basis of that positional error, the positional errors far away from the original point are measured. Using this analogy, the error information on the positional points on the entire plane can be obtained. The process outlined above is called the relay method. Test results indicate that the accuracy and repeatability are high, and the method can be used to calibrate geometric errors on the plane of CNC machine tools after backlash errors have been well compensated.
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Research on physical shape preserving curve reconstruction
TANG Kelun, ZHANG Xiangwei, CHENG Siyuan, XIONG Hanwei, ZHANG Hong
Front. Mech. Eng.. 2007, 2 (3): 305-309.
https://doi.org/10.1007/s11465-007-0054-2
Fusion of various data is an effective way to improve the precision and efficiency of acquiring information in reverse engineering. A method of physical shape preserving curve reconstruction is proposed to better realize the data fusion of coordinate measuring machine (CMM) and visual information. From the principle of materials mechanics, the strain energy of the curve corresponding to the distortion is advanced as the internal energy, and the elastic potential energy of the curve is established, using a few precise measured data points as the equilibrium position, to be the external energy. On the basis of the principle of variation calculus, the basic spline finite element method (B-spline FEM) is used to determine the equilibrium position of curve deformation. Numerical simulation indicates that there is an extremely good agreement between the new fitted curve and the actual curve.
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Experimental research on cyclone performance at high temperature
LI Wenqi, CHEN Jianyi
Front. Mech. Eng.. 2007, 2 (3): 310-317.
https://doi.org/10.1007/s11465-007-0055-1
To predict the influence of operating temperatures on cyclone performance, an experimental investigation was conducted on particle separation in a reverse flow, tangential volute-inlet cyclone separator with a diameter of 300 mm and with air heated up to 973 K. The test powder silica has a mass median diameter of 10 um, while inlet velocity range was 12-36 m/s. Both the separation efficiency and pressure drop of the cyclone were measured as a function of the inlet velocity and operating temperature. At the same inlet velocity, both the separation efficiency and pressure drop decrease with increasing temperature. In addition, optimum inlet velocity, at which the cyclone has its highest separation efficiency, tends to increase with a rise in temperature. An analysis on our own data and published results has shown that the fractional efficiency of a cyclone is a definite function of dimensionless numbers such as the Stokes number, the Reynolds number, the Froude number, dimensionless cyclone inlet area, and dimensionless outlet diameter. A nondimensional experimental correlation of the cyclone performance, including the influence of temperature, was obtained on the basis of our own previous work. The prediction of the influence of temperature on separation efficiencies and pressure drops is in fairly good agreement with experimental results.
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Design method and magnetic field analysis of axial-magnetized permanent magnet micromotor
YANG Jiewei, WU Yihui, JIA Hongguang, ZHANG Ping, WANG Shurong
Front. Mech. Eng.. 2007, 2 (3): 318-322.
https://doi.org/10.1007/s11465-007-0056-0
To investigate the impact of size on its performance in designing an axial-magnetized permanent magnet micro motor, the finite element method is adopted to simulate the magnetic field of the dual rotor motor, and the flux density wave form distributed in the airgap is obtained. The influence of the external dimensions, pole numbers and magnet thicknesses of the rotor, and the airgap distances on the flux density, are analyzed and analytical results are given. With the increase of the airgap distance, the flux density under more poles reduces more quickly than under fewer poles. With the increase of the magnet thickness, the flux density is a rising curve, and after the magnet thickness attains a certain point, the flux density is almost a constant. While reducing the diameter of the rotor, the decrease of the flux density slows down as magnet thickness is reduced. To avoid having a seriously distorted waveform, the distance between inner and outer radii of the rotor must be larger than 1.5 millimeter. Results of the magnetic field analysis can guide a microminiaturization of the motor. Moreover, the results are analyzed theoretically and the simulated values are almost consistent with the experimental values.
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Error analysis of the parameters for non-coaxial grazing X-ray microscope
ZHAO Lingling, HU Jiasheng, LI Xiang
Front. Mech. Eng.. 2007, 2 (3): 323-329.
https://doi.org/10.1007/s11465-007-0057-z
A non-coaxial grazing X-ray microscope, consisting of four spherical mirrors, is designed for diagnosis of inertial confinement fusion (ICF). The aberrations and imaging quality of the microscope are analyzed. To acquire excellent imaging quality, suitable tolerances for manufacturing and assembling the microscope are necessary. This paper researches the changes of Gauss parameters and aberrations due to component and subsystem parameters (such as the radius of the mirror, angle between mirrors, grazing angle, object distance, etc.). Here, spot diagrams and modulation transfer function (MTF) are first adopted to quantitatively evaluate the imaging quality of the microscope. Suitable manufacturing tolerances of components and assembly tolerances of the system are established on the basis of the discussion and analysis. A set of non-coaxial grazing X-ray microscopes is manufactured based on the tolerances. In site tests of ICF, the images with high resolution are obtained by the microscope.
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Quality monitoring of resistance spot welding based on electrode displacement characteristics analysis
ZHANG Pengxian, ZHANG Hongjie, CHEN Jianhong, MA Yuezhou
Front. Mech. Eng.. 2007, 2 (3): 330-335.
https://doi.org/10.1007/s11465-007-0058-y
A new method is developed to monitor joint quality based on the information collection and process in spot welding. First, twelve parameters related to weld quality are mined from electrode displacement signal on the basis of different phases of nugget formation marked by simultaneous dynamic resistance signal. Second, through correlation analysis of the parameters and taking tensile-shear strength of the spot-welded joint as evaluation target, different characteristic parameters are reasonably selected. At the same time, linear regression, nonlinear regression and radial basis function (RBF) neural network models are set up to evaluate weld quality between the selected parameters and tensile-shear strength. Finally, the validity of the proposed models is certified. Results show that all of the models can be used to monitor joint quality. For the RBF neural network model, which is more effective for monitoring weld quality than the others, the average error validated is 2.88% and the maximal error validated is under 10%.
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Functional tolerance theory in incremental growth design
YANG Bo, ZE Xiangbo, YANG Tao
Front. Mech. Eng.. 2007, 2 (3): 336-343.
https://doi.org/10.1007/s11465-007-0059-x
The evolutionary tolerance design strategy and its characteristics are studied on the basis of automation technology in the product structure design. To guarantee a successful transformation from the functional requirement to geometry constraints between parts, and finally to dimension constraints, a functional tolerance design theory in the process of product growth design is put forward. A mathematical model with a correlated sensitivity function between cost and the tolerance is created, in which the design cost, the manufacturing cost, the usage cost, and the depreciation cost of the product are regarded as control constraints of the tolerance allocation. Considering these costs, a multifactor-cost function to express quality loss of the product is applied into the model. In the mathematical model, the minimum cost is used as the objective function; a reasonable process capability index, the assembly function, and assembly quality are taken as the constraints; and depreciation cost in the objective function is expressed as the discount rate terminology in economics. Thus, allocation of the dimension tolerance as the function and cost over the whole lifetime of the product is realized. Finally, a design example is used to demonstrate the successful application of the proposed functional tolerance theory in the incremental growth design of the product.
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Basic model study on efficiency evaluation in collaborative design work process
XIE Qiu, YANG Yu, LI Xiaoli, ZHAO Ningyu
Front. Mech. Eng.. 2007, 2 (3): 344-349.
https://doi.org/10.1007/s11465-007-0060-4
During the efficiency evaluation process of collaborative design work, because of the lack of efficiency evaluation models, a basic analytical model for collaborative design work efficiency evaluation is proposed in this paper. First, the characteristics of the networked collaborative design system work process were studied; then, in accordance with those characteristics, a basic analytical model is created. This model, which is built for centralized collaborative design work, includes an analytical frame, a process view model, a function view model and an information view model. Finally, the application process and steps of this basic analytical model are elaborated when used for efficiency evaluation through an experiment.
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Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel
ZHAO Qingliang, Brinksmeier Ekkard, Riemer Oltmann, Rickens Kai
Front. Mech. Eng.. 2007, 2 (3): 350-355.
https://doi.org/10.1007/s11465-007-0061-3
In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 yD grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope. The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential of super abrasive diamond wheels in ductile machining brittle materials.
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Novel precision piezoelectric step rotary actuator
LIU Jianfang, YANG Zhigang, ZHAO Hongwei, CHENG Guangming
Front. Mech. Eng.. 2007, 2 (3): 356-360.
https://doi.org/10.1007/s11465-007-0062-2
A novel piezoelectric (PZT) precision step rotary actuator was developed on the basis of PZT technology. It adopts the principle of bionics and works with an inside anchoring/loosening of the stator and a distortion structure of the uniformly distributed thin flexible hinge to solve problems such as ineffective anchoring/loosening, low step rotary frequency, small travel, poor resolution, low speed and unsteady output. The developed actuator is characterized by high frequency (30 Hz), high speed (380 μrad/s), large travel (>270º), high resolution (1 μrad/step), and work stability. It greatly improves the ability to drive the existing PZT step rotary actuator. The new actuator can be applied in the field of micromanipulation and precision engineering, including precision driving and positioning and optics engineering.
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22 articles
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