共查询到20条相似文献,搜索用时 15 毫秒
1.
Minsung Choi Seongyong Eom Yonmo Sung Kiyoul Noh Gyungmin Choi 《Journal of Mechanical Science and Technology》2018,32(5):2127-2139
The objective of this paper is to provide quantitative information of uniform impact forces on the sprayed surface in order to optimize the multi-nozzle spray etching system. Spray characteristics obtained from optical non-intrusive measurements using particle image velocimetry (PIV) and particle motion analysis system (PMAS) are measured in single- and twin-nozzle sprays, and then the multi-nozzle spray characteristics is simulated based on those of measurement data. The influences of the multi-nozzle arrangement, nozzle pitch, and pipe pitch on the spray characteristics such as droplets’ velocity, diameter, number density, impact force and their uniformity are properly evaluated. The experimental cases E1 and E2 represent single-spray nozzle A and B, respectively. For twin-spray tests, three nozzle combinations, namely E3 (nozzle A-A), E4 (nozzle A-B) and E5 (nozzle B-B) are considered with different nozzle pitches. The multi-spray simulation cases S1 and S6 represent the multi-spray cases with a homo-nozzle arrays which is consisted in all nozzles of nozzle A or B. For cases from case S2 to S5, the multi-spray cases with a hybrid-nozzle arrays which is consisted in all nozzles of nozzle A and B. The results show that the impact force increases approximately twice as much for changing of experimental test cases from E1 to E5 owing to the differences in nozzle characteristics of single-sprays and the overlap region between two adjacent nozzles. For the multi-nozzle spray simulation, the uniformity of impact force (UI) is increased with increasing the number of nozzle B which has larger orifice diameter and a wider spray angle. The optimum multi-nozzle spray arrangement is case S4 with more than 90 % UI, based on the fact that the UI is quite stable with increasing the nozzle pitch ranging from 90 mm to 145 mm. 相似文献
2.
Materials are either removed from or added to a device, usually in a selective manner with using thin and/or thick film manufacturing
processes that transfer the lithographic patterns into integrated circuits (ICs) or three-dimensional micromachines. This
study deals with material removal by chemically assisted mechanical micromachining. Two methods are used chemical mechanical
machining method are introduced in this paper. One, mechanically assisted chemical etching, is applied to fabricate a micro
beam such as cantilever, and another is chemically assisted mechanical micromachining to fabricate microstructure such as
micropattern, microchannel. The results are discussed. 相似文献
3.
Tzu-Chiang Liu Rong-Kwei Li Meng-Chi Chen 《The International Journal of Advanced Manufacturing Technology》2006,27(11-12):1211-1216
The electronic industry is rapidly developing, creating high demand for IC production. Etched semiconductor lead frames are the basic material used in IC packaging. IC packaging requires high-precision lead frames. The dimensions of the pilot hole are generally required to be highly precise in lead frame manufacturing. The photo-etching process must control the dimension of the pilot hole and record the manufacturing data of the etching machine and inspection data. This study presents the development of an artificial neural network (ANN) model that can be applied to construct the predicting model. The predictive model can estimate the dimensions of the pilot hole and thus determine the process parameters needed to improve lead frame quality in the etching process. 相似文献
4.
Kun-Lin Hsieh 《The International Journal of Advanced Manufacturing Technology》2006,28(5-6):584-591
This study proposes an effective means of applying a neural network approach to parameter optimization for a multi-response
problem. No matter what type of experimental designs are being employed, the proposed approach can be directly applied. In
addition, the design factors with level settings or with continuous values can be also solved with the proposed approach.
Not only can parameter optimization be achieved, but the effects of the control factors reacting on a multi-response system
can also be simultaneously determined. An illustrative example given courtesy of a lead frame manufacturer in Taiwan is employed
to demonstrate the effectiveness of the proposed approach . 相似文献
5.
This paper analyzes heterogeneous distribution of branch-like structure at the downstream region of the spray. The liquid
and vapor phase of the spray are obtained using a 35mm still camera and CCD camera in order to investigate spray structure
of evaporating diesel spray. There have been many studies conducted on diesel spray structure but have yet only focused on
the analyses of 2-D structure. There are a few information which is concerned with 3-D structure analysis of evaporating spray.
The heterogeneous distribution of droplets in inner spray affects the mixture formation of diesel spray and the combustion
characteristics of the diesel engines. In this study, the laser beam of 2-D plane was used in order to investigate 3-D structure
of evaporating spray. The incident laser beam was offset on the central axis of the spray. From the analysis of images taken
by offset laser beam, we will examine the formation mechanism of heterogeneous distribution of the diesel spray by vortex
flow at the downstream of the spray. The images of liquid and vapor phase of free spray are simultaneously taken through an
exciplex fluorescence method. Through this, the branch-like structure consisting of heterogeneous distribution of the droplets
forms high concentrated vapor phase at the periphery of droplets and at the spray tip. 相似文献
6.
Sung Won Youn Hyun Il Kim Chung Gil Kang 《Journal of Mechanical Science and Technology》2005,19(11):2112-2121
Nanoprobe-based lithography techniques have attracted tremendous interst. However, most of these techniques have the several
technical problems still to be resolved such as low throughput, reproducibility, extensive processing time and tip-wear problem.
We considered that a patterning process with a multi-array tip can be a solution. The purpose of this study is to build up
the database in order to design a multi-array tip for patterning. In this study, the effects of tip-geometry factors (indenter
shape and tip radius) and process parameters (pattern pitch and normal load) on the deformation behaviors and etching chracteristics
of hard-brittle materials (Pyrex 7740 glass and silicon) were investigated by using both experiment and finite element analysis.
The results of the investigation will be applied to the design of the multi-array tip for patterning. 相似文献
7.
8.
The objective of this study is to investigate the effects of fuel temperature on the spray characteristics of a dual-orifice
type swirl injector used in a gas turbine. The major parameters affecting spray characteristics are fuel temperature and injection
pressure entering into the injector. In this study, the spray characteristics of a dual-orifice type swirl injector are investigated
by varying fuel temperature from — 30°C to 120°C and injection pressure from 0.29 to 0.69 MPa. Two kinds of fuel having different
surface tension and viscosity are chosen as atomizing fluids. As a result, injection instability occurs in the low fuel temperature
range due to icing phenomenon and fuel property change with a decrease of fuel temperature. As the injection pressure increases,
the range of kinematic viscosity for stable atomization becomes wider. The properties controlling the SMD of spray is substantially
different according to the fuel temperature range. 相似文献
9.
Hongseok Choi Yong Yang Xiaochun Li 《The International Journal of Advanced Manufacturing Technology》2005,26(4):335-341
Solid freeform fabrication has attracted considerable attention lately because of its ability to build a 3D structure with a complex and arbitrary shape. This work presents initial studies to adapt this technology for the fabrication of meso-/micro-3D structures. A pulsed Nd:YAG laser was used for laser microdeposition (additive) and micromachining (subtractive) processes. An ultrasonic-based micropowder feeding system was developed to generate precise patterns of micropowders on a substrate without any pre-processing. Laser microdeposition of copper and stainless steel micropowders was accomplished. The characterization of micromachining was performed on stainless steel and copper plates with a laser beam of wavelengths of 355 nm and 266 nm. The integration of laser microdeposition and micromachining processes improved the resolution and edge quality of the meso-/micropatterns. 相似文献
10.
Experimental study on fabrication and evaluation of micro pyramid-structured silicon surface using a V-tip of diamond grinding wheel 总被引:3,自引:0,他引:3
A mechanical fabrication of micro pyramid-structured silicon surface is proposed using crossed grooving with a 60° V-tip of diamond grinding wheel. It can obtain high form-accuracy, good surface quality and efficient productivity in contrast to laser machining and etching, and also assure a high aspect ratio in contrast to other mechanical processes. In order to describe its micro-structured topography, a white-light interferometer was employed, and its measured point cloud was matched using an Iterative Closest Point (ICP) algorithm. In micro grinding, a novel CNC mutual-wear truing was first developed to sharpen the wheel V-tip; then, the effects of microscopic wheel topography, silicon crystal-orientation and grinding parameter were investigated on ground micro-topography, truing ratio and material removal ratio; finally, its form-accuracy, pyramid top radius, groove tip radius, surface roughness and aspect ratio were evaluated. It is shown that better microscopic grain protrusion topography on wheel V-tip produces much larger material removal ratio and much better micro-structured topography in micro grinding, but it leads to much less truing ratio in finer GC truing. In micro grinding, silicon crystal-orientation has little effect on micro-structured topography due to diamond crystal-orientations that are randomly distributed on wheel V-tip. Although the micro pyramid-structured form error is only about 3.4 μm, its V-groove bottom and pyramidal top have very large form errors (23.1-47.9 μm) due to the sharpness of wheel V-tip and the frangibility of micro pyramid top. On increasing feed speed, its pyramid top radius decreases and its groove tip radius slightly increases, ultimately leading to an increase in aspect ratio, whereas its surface quality descends. It is concluded that the micro-pyramid arrays may be precisely patterned on silicon surface using a SD600 wheel with crossed tool paths, on-machine V-tip truing and the depth of cut in 1 μm. 相似文献
11.
12.
The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated.
The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore,
this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the
experimental parameter, is changed from 22 MPa to 112 MPa using a high pressure injection system (ECD-U2). Also, we conducted
simulation study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images
of liquid and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results,
the vapor concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure
than in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements
with experimental results. 相似文献
13.
本文建立直接固体进样-石墨炉原子吸收光谱法检测食品中铅的快速方法,采用铅标准溶液绘制标准曲线,0.1%Pd(NO_3)_2溶液作基体改进剂,优化石墨炉升温程序。方法的定量检出限为0.050ng,在奶粉、饼干基质的添加水平为0.5ng、1.0ng、2.0ng,回收率为95%~104%(n=6)。采用本方法对食品中铅进行测定,结果与微波消解石墨炉原子吸收法(AAS)和电感耦合等离子体质谱法(ICP-MS)的测定结果基本一致。固体样品直接测定,能避免样品消解过程中带来的污染,节约分析时间和成本。 相似文献
14.
电解加工在微细制造技术中的应用研究 总被引:3,自引:0,他引:3
电解加工是利用阳极金属电化学溶解原理来去除材料的制造技术,这种微去除方式使得电解具有微细加工的可能,这里着重探讨了高频窄脉冲微细电解加工技术、电液束微细电解加工技术和利用电解制备微细电极的工作原理,技术特点,应用领域和加工精度,并详细的讨论了目前微细电解加工脉冲电源和加工设备的研制和发展。 相似文献
15.
16.
The effects of change in injection pressure on spray structure in high temperature and pressure field have been investigated.
The analysis of liquid and vapor phases of injected fuel is important for emissions control of diesel engines. Therefore,
this work examines the evaporating spray structure using a constant volume vessel. The injection pressure is selected as the
experimental parameter, is changed from 400 bar to 800 bar by using a common rail injection system. Also, we conducted simulation
study by modified KIVA-II code. The results of simulation study are compared with experimental results. The images of liquid
and vapor phase for free spray were simultaneously taken by exciplex fluorescence method. As experimental results, the vapor
concentration of injected fuel is leaner due to the increase of atomization in the case of the high injection pressure than
in that of the low injection pressure. The calculated results obtained by modified KIVA-II code show good agreements with
experimental results. 相似文献
17.
为了获得更好的微压印工艺填充效果,利用有限元方法研究模压工艺的主要参数压印温度、压印力和压印时间对压印效果的影响,并对工艺参数进行优化;对压印过程中不同的模具结构的应力分布进行了研究.仿真结果表明,工艺参数优化为480℃,30N,1800s后,模具的填充率达到97.2%;对不同的模具结构,有相同的应力分布区域,在模具拐... 相似文献
18.
Journal of Mechanical Science and Technology - One of the major challenges in producing composites is the uniform distribution of micro/nano-sized particles in the metal matrix by powder metallurgy... 相似文献
19.
The characteristics of gear meshing vibration undesgo change as the vibration is transmitted from the gear to the housing.
Therefore, vibration transmission characteristics of helical gear systems must be understood before the effective methods
of reducing gear noise can be found. In this work, using a helical gear with different lead errors, the gear vibration in
the rotational direction and the bearing vibration are measured. The frequency characteristics of gear and bearing vibration
are investigated and a comparson is also provided. 相似文献
20.
Servo scanning 3D micro electrical discharge machining (3D SSMEDM) is a novel and effective method in fabricating complex 3D micro structures with high aspect ratio on conducting materials.In 3D SSMEDM process,the axial wear of tool electrode can be compensated automatically by servo-keeping discharge gap,instead of the traditional methods that depend on experiential models or intermittent compensation.However,the effects of process parameters on 3D SSMEDM have not been reported up until now.In this study,the emphasis is laid on the effects of pulse duration,peak current,machining polarity,track style,track overlap,and scanning velocity on the 3D SSMEDM performances of machining efficiency,processing status,and surface accuracy.A series of experiments were carried out by machining a micro-rectangle cavity (900 μm×600 μm) on doped silicon.The experimental results were obtained as follows.Peak current plays a main role in machining efficiency and surface accuracy.Pulse duration affects obviously the stability of discharge state.The material removal rate of cathode processing is about 3/5 of that of anode processing.Compared with direction-parallel path,contour-parallel path is better in counteracting the lateral wear of tool electrode end.Scanning velocity should be selected moderately to avoid electric arc and short.Track overlap should be slightly less than the radius of tool electrode.In addition,a typical 3D micro structure of eye shape was machined based on the optimized process parameters.These results are beneficial to improve machining stability,accuracy,and efficiency in 3D SSMEDM. 相似文献