- 颜永年;李生杰;张人佶;林峰;吴任东;卢清萍;熊卓;王小红;
The rapid prototyping and manufacturing technology (RPM), is an integration of many different disciplines. It is based on an advanced dispersed-accumulated forming principle and originated from 1980s. It generates an entity by first forming a series of layers according to the dispersed section information of the digital model, and then piling the formed layers sequentially together. It is capable of forming parts with complicated structures and non-homogeneous materials. Traditional RPM techniques are mainly used as prototypes in product invention process, such as stereolithography, three-dimensional printing, laminated object manufacturing, and fused deposition modeling. Later, with the progress of material and enabling technology, many new RPM techniques emerged out and have been already applied in the fields such as rapid tooling/moulding, direct formed usable part, nano-/micro-RPM, and biomanufacturing. This high flexible digital manufacturing method has a likely ability to become an almighty forming technology.
2009年S1期 v.14 1-12页 [查看摘要][在线阅读][下载 567K] [下载次数：858 ] |[网刊下载次数：0 ] |[引用频次：88 ] |[阅读次数：2 ] - GIBSON Ian;SAVALANI Monica M;LAM Christopher X F;OLKOWSKI Radoslow;EKAPUTRA Andrew K;TAN Kim Cheng;HUTMACHER Dietmar W;
This paper describes fabrication of scaffolds for load-bearing applications, with primary consideration from the manufacturing perspective. An extrusion device, inspired by the FDM process, was used to create scaffolds from a variety of different polymeric materials and mixtures. The effectiveness of these scaffolds to host cells for bone regeneration has been investigated. This ongoing work has generated significant insight into the future direction of research and the possibilities of developing scaffolds for medium/high load-bearing applications.
2009年S1期 v.14 13-19页 [查看摘要][在线阅读][下载 704K] [下载次数：30 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - NOTARBERARDINO Bruno;BAKER Matthew;TABOR Gavin;TURNER Irene;YANG Lincoln;
Bio-scaffolds which are most commonly open celled porous structures are increasingly used for tissue engineering and regenerative medicine. A number of studies have shown that the bulk properties of such irregular structures are poorly modeled using idealized unit cell approaches. The paper therefore uses novel image based meshing techniques to explore both fluid flow and bulk structural properties of a bone scaffold, as accurate modeling of bio-scaffolds with non-uniform cellular structures is very important for the development of optimal scaffolds for tissue engineering application. In this study, a porous hydroxyapatite/tricalcium phosphate (HA/TCP) bone scaffold has been scanned in a Micro-CT scanner, and converted into a volumetric mesh using image processing software developed by the authors. The resulting mesh was then exported to commercial FEA and CFD solvers for analysis. Initial FEA and CFD studies have shown promising results and have highlighted the importance of accurate modeling to understand how microstructures influence the mechanical property of the scaffold, and to analyze flow regimes through the sample. The work highlights the potential use of image based meshing for the ad hoc characterization of scaffolds as well as for assisting in the design of scaffolds with tailored strength, stiffness, and transport properties.
2009年S1期 v.14 20-23页 [查看摘要][在线阅读][下载 498K] [下载次数：46 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - RAHMATI Sadegh;SHIRAZI Farid;BAGHAYERI Hesam;
Rapid prototyping (RP) is a computerized fabrication technology that additively builds highly complex three-dimensional physical objects layer by layer using data generated by computer, for example CAD or digital graphic. Three-dimensional printing (3DP) is one of such technologies that employ ink-jet printing technology for processing powder materials. During fabrication, a printer head is used to print a liquid on to thin layers of powder following the object's profile as generated by the system computer. This work looks at redesigning 3DP machine, using piezoelectric demand-mode technology head in order to improve accuracy, surface finishing and color quality of constructed models. The layers created with aforesaid system are between 25 to 150 μm (steps of 25 μm).
2009年S1期 v.14 24-28页 [查看摘要][在线阅读][下载 416K] [下载次数：207 ] |[网刊下载次数：0 ] |[引用频次：4 ] |[阅读次数：0 ] - MOSTAFA Nikzad;SYED Hasan Masood;IGOR Sbarski;ANDREW Groth;
Fused deposition modelling (FDM) is a filament based rapid prototyping system which offers the possibility of introducing new composite material for the FDM process as long as the new material can be made in feedstock filament form. Swinburne has been undertaking extensive research in development of new composite materials involving acrylonitrile-butadiene-styrene (ABS) and other materials including metals. In order to predict the behaviour of new ABS based composite materials in the course of FDM process, it is necessary to investigate the flow of the composite material in liquefier head. No such study is available considering the geometry of the liquefier head. This paper presents 2-D and 3-D numerical analysis of melt flow behaviour of a representative ABS-iron composite through the 90-degree bent tube of the liquefier head of the fused deposition modelling process using ANSYS FLOTRAN and CFX finite element packages. Main flow parameters including temperature, velocity, and pressure drop have been investigated. Filaments of the filled ABS have been fabricated and characterized to verify the possibility of prototyping using the new material on the current FDM machine. Results provide promising information in developing the melt flow modelling of metal-plastic composites and in optimising the FDM parameters for better part quality with such composites.
2009年S1期 v.14 29-37页 [查看摘要][在线阅读][下载 651K] [下载次数：170 ] |[网刊下载次数：0 ] |[引用频次：23 ] |[阅读次数：0 ] - 杨晓冬;刘鹏;
Three-dimensional reconstructions based on serial fault data can be divided into boundary contour splicing and end contour closure. In boundary contour splicing, the Delaunay triangulation algorithm can generate long, narrow triangles or radial shapes and with end contour closure, the Delaunay triangulation based on the determination of the convex-concave vertices tends to generate long, narrow triangles and triangles whose sizes differ greatly, and in some cases failure. This paper presents a Delaunay triangulation algorithm based on the shortest distance first principle for boundary contour splicing and an improved algorithm which combines Delaunay triangulation based on the determination of convex-concave vertices with interpolation for end contour closure. The results show that the algorithms retain the original advantages of the algorithms while increasing the triangulation effectiveness and enhancing the universality of the algorithms.
2009年S1期 v.14 38-42页 [查看摘要][在线阅读][下载 405K] [下载次数：36 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 朱根松;周天瑞;周捷;
Feature recognition and surface reconstruction from point clouds are difficulties in reverse engineering. A new surface reconstruction algorithm for slicing point cloud was presented. The contours of slice were extracted. Then, the intersection of two adjacent curve segments in the contour was obtained and curves feature was extracted. Finally, adjacent section contours were matched directly with Fourier-Mellin curve matching method for feature extraction. An example of 3-D model reconstruction shows the reliability and application of the algorithm.
2009年S1期 v.14 43-46页 [查看摘要][在线阅读][下载 174K] [下载次数：110 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 陈田;杜晓明;郑建明;邹欣珏;
Various types of cutting tools are known and are in use for machining parts. The dimensional parameters associated with cutting tools need to be estimated and compared to the desired values for determining their cutting performance. In this paper, a data analysis methodology for extracting parameters from a measured point set corresponding to the surface of a cutting tool is provided. We propose that the 3-D data can be simplified into 2-D data or regular data by virtually slicing it at a predetermined section or by projecting it onto a same axial plane after a simple fixed-axis rotation. A plurality of curves can be generated and optimized based on the obtained 2-D points on a cross section for calculating the section parameters, including radial (axial) rake angle, relief angle, and land width. Other dimensional parameters can also be extracted from the contour of the presented rotary axial projection data. The experimental results have shown that the approaches elaborated in this paper are effective and robust, which can be potentially extended to other applications such as the inspection of similar parts and their parameters extraction.
2009年S1期 v.14 47-55页 [查看摘要][在线阅读][下载 492K] [下载次数：53 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - 刘斌;上官宁;江开勇;林俊义;
For mesh reconstruction problems of point cloud models which have similar topological structure, a rapid and efficient method is presented to reconstruct triangular mesh surface. Based on projections of point cloud slicing that correspond to template sectional curves, the method constructs topological relevant information among discrete points, which makes unorganized points ordering and builds up optimal approximated B-spline curve, resamples every curve according to its curvature distribution and performes triangular mesh division on it. Finally, surface reconstruction is achieved. The experimental results demonstrate that the surface reconstruction is done as the point cloud hole is filled simultaneously.
2009年S1期 v.14 56-61页 [查看摘要][在线阅读][下载 420K] [下载次数：98 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - 周钢;李中伟;王从军;史玉升;
Human expression rapid reconstruction has many potential applications in entertainment and social security. In this work, a rapid human expression measurement system based on a digital fringe projection and phase-shift technique is developed. The measurement system consists of a digital light processing (DLP) projector and a high-speed change-coupled device (CCD) camera. The DLP projector is used to project computer-generated fringe patterns onto the human face, and the high-speed CCD camera synchronized with the projector acquires the fringe images at a frame rate of 30 frames/s. Based on a three-step phase-shifting method and an accurate phase-height mapping algorithm, each frame of the 3-D human expression can be reconstructed. The principle of the proposed method is described and some experimental results are presented to demonstrate its performance. The experiment results show that the measurement system can reconstruct accurate 3-D human expression. An obvious merit of this method is that it can reconstruct the 3-D human expression in a very short time and it is not sensitive to the movement of the face during the measurement processing.
2009年S1期 v.14 62-65页 [查看摘要][在线阅读][下载 322K] [下载次数：71 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - 秦大辉;李中伟;王从军;史玉升;
A new approach for three dimensional (3-D) shape measurement was proposed based on colorcoded fringe and neural networks. By applying the phase-shift technique to fringe projection, point clouds were generated with high spatial resolution and limited accuracy. The picture element correspondence problem was solved by using projected color-coded fringes with different orientations. Once the high accurate corresponding points were decided, high precision dense 3-D points cloud was calculated by the well trained net. High spatial resolution can be obtained by the phase-shift technique and high accuracy 3-D object point coordinates are achieved by the well trained net, which is not dependent on the camera model and will work for any type of camera. Some experiments verify the performance of this method.
2009年S1期 v.14 66-70页 [查看摘要][在线阅读][下载 507K] [下载次数：118 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - 上官景昌;阎艳;刘海涛;王国新;赵博;
Powerful expressive ability of semantic information, to be easily computed and flexibility are basic features of digital product model (DPM). Using ontology and object-oriented principle (OOP) together to cope with problems in modeling is brought forward in this paper. The two are widely used and do well in modeling, but they each alone cannot cope with all issues and new challenges. Three basic requests are pointed out in DPM modeling. Status, problems, and root of current non-semantic and semantic models are introduced. Ontology, OOP, and their difference are introduced. It is found that the two are entirely complementary with each other. How to assign the roles and to cooperate for the two in coping with the three basic issues in DPM modeling are explained in detail.
2009年S1期 v.14 71-76页 [查看摘要][在线阅读][下载 108K] [下载次数：86 ] |[网刊下载次数：0 ] |[引用频次：4 ] |[阅读次数：0 ] - 赵灿;孟祥林;
This paper is to improve the speed of k-nearest-neighbor search and put forward algorithms related to tangent plane estimation based on existing methods. Starting from the points cloud, the algorithm segments the whole data into many different small cubes in space, and the size of cube is related to the density of the points cloud. Considering the position of the point in the cube, the algorithm enlarges the area around the given point step by step until the k-nearest-neighbor is accomplished. The neighbor's least-squares tangent plane is estimated. In order to orient the planes, the k-nearest-neighbor is introduced into the problem of seeking the minimum spanning trees instead of searching the whole data. The research proved that the algorithms put forward in this paper were effective in processing data in short time and with high precision. The theory was useful for the practical application in reverse engineering and other areas related. Solution for finding k-nearest-neighbor problem, which still costs much time in present, was provided, and a propagation algorithm for orienting the planes was also discussed. The algorithm chose the orientation among the k-nearest-neighbor of the current point.
2009年S1期 v.14 77-81页 [查看摘要][在线阅读][下载 351K] [下载次数：100 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - 付红圣;高亮;鞠鲁粤;刘俞章;
The purpose of this paper is to overcome the limitations of the traditional cranial defects restoration technique and better satisfy the aesthetic and comfort demands of different patients. An arithmetic profile curve blending technique was used based on a well-proportioned points cloud data obtained by analyzing computer tomography (CT) images of the patients. This technique uses reverse engineering technique to reconstruct a model of the defective cranium, taking all the characteristics of the protruding cranium into consideration to check the form and appropriateness of the restoration and to adjust the surface in real time to obtain the ideal shape. Then, the model is transferred to a multiple-point forming (MPF) pressure machine to produce a titanium alloy restoration model. The system has greater flexibility, shorter production cycles, and lower cost through the use of digital production technology, guarantees the quality of the cranial defects restoration model, reduces the surgical risks, and alleviates the patients' pain. In addition, an improved contour curved bridge algorithm technique is used to repair any cranium defects on the contour curve to make the contour more complete and closed.
2009年S1期 v.14 82-88页 [查看摘要][在线阅读][下载 333K] [下载次数：67 ] |[网刊下载次数：0 ] |[引用频次：3 ] |[阅读次数：0 ] - 钟山;卢雪燕;
An approximating algorithm on handling 3-D points cloud data was discussed for reconstruction of complicated curved surface. In this algorithm, the coordinate information of nodes both in internal and external regions of partition interpolation was used to realize minimized least squares approximation error of surface fitting. The changes between internal and external interpolation regions are continuous and smooth. Meanwhile, surface shape has properties of local controllability, variation reduction, and convex hull. The practical example shows that this algorithm possesses a higher accuracy of curved surface reconstruction and also improves the distortion of curved surface reconstruction when typical approximating algorithms and unstable operation are used.
2009年S1期 v.14 89-93页 [查看摘要][在线阅读][下载 349K] [下载次数：44 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 埃文思·朱利安;杨守峰;
A view of manufacturing processes is presented in which five distinct categories are defined as casting, deformation, machining, joining, and solid freeforming. Solid freeforming is essentially biomimetic and shares problems of morphogenesis with natural processes. Our team in University of London has been exploring three mechanisms of solid freeforming. In dry powder deposition and direct ink-jet printing, the emphasis has turned to the problem of delivering a complex shape in which the three dimensional spatial arrangement of composition is delivered from the design file. In extrusion freeforming, the aim is to control microstructure at hierarchical levels also from the design file. The quest for 3-D functional gradients is satisfied by acoustic and ultrasonic dispensing and mixing of powders so that each layer can be patterned. These methods could be extended to deliver the complex patterns demanded by left-handed microwave metamaterials. Dry powder deposition and direct ink-jet printing are turning towards combinatorial methods in which multiple sample libraries are used to accelerate discovery. In turn, this paves the way for 'autonomous research machines' which steer their own search refinements in response to our requests for new materials. In this way, solid freeforming used for sample preparation can give an 'arm' to an intelligent machine so that it can conduct its own experimentation and learning; an idea that originated with Alan Turing in the late 1940s.
2009年S1期 v.14 94-99页 [查看摘要][在线阅读][下载 604K] [下载次数：46 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - Mario Monzón;Pedro M Hernández;Antonio N Benítez;María D Marrero;ngel Fernández;
One of the most important issues to resolve in parts manufactured from rapid manufacturing (RM) technologies is to know their behavior working under real conditions. Total quality manufacturing (TQM) is only possible if mechanical properties are well known in the design stage depending on the processing parameters. This work is mainly focused on testing of several samples made with different selective laser sintering (SLS) parameters and technologies. This procedure is the starting point to establish a basis for designing for RM and the standardization of RM testing. The experiments and the analysis of variance (ANOVA) analyzed the effects of several factors on mechanical properties. The SLS technologies were 3DSystem and EOS. The results show which factor has a large effect on the variables and the interaction between them. The conclusions are very useful for developing rules for designing (designing for RM) and creating new standard rules (ISO, AISI, and DIN) for RM materials and parts testing. The ANOVA gives a better knowledge of the effects of these factors and eliminates unimportant parameters.
2009年S1期 v.14 100-107页 [查看摘要][在线阅读][下载 302K] [下载次数：40 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - RAHMATI Sadegh;REZAEI Mohamad Reza;AKBARI Javad;
A rapid wax injection tool of a gearbox shift fork was designed, simulated, and manufactured using rapid prototyping and rapid tooling technology to save time and cost of producing wax models used for the investment casting process. CAE simulation softwares, in particular, MoldFlow, are used to get wax injection moulding parameters such as filling parameters, temperature profiles, freeze time, speed, and pressure. The results of this research were compared with conventional wax model production methods. The criteria of such comparison were based upon parameters such as time, cost, and other related characteristics, which resulted in saving of 50% in time and 60% in cost. In this research, design, assembly, and wax injection operation of the wax tool took 10 days. Considering the fact that wax melting temperature is as low as 70℃ and injection pressure of 0.5 MPa, the tool suffers no damage due to the thermal and pressure stresses, leading to the mass production of wax models.
2009年S1期 v.14 108-115页 [查看摘要][在线阅读][下载 389K] [下载次数：213 ] |[网刊下载次数：0 ] |[引用频次：9 ] |[阅读次数：0 ] - 刘丰;张人佶;
Scaffolds require individual external shape and well-defined internal structure, which is of great importance for tissue engineering. Rapid prototyping (RP) uses layer-manufacturing strategies to create physical objects and has the advantage on scaffold fabrication. A new RP technology called aerodynamically assisted tip-pen direct writing was developed to construct the complex architectures. Compared with the traditional nozzle, the new nozzle has a micro-tip in the center of the micro-hole. The flow is determined by the gap between the micro-hole and micro-tip, which makes it practical for more accurate flow control. A highly accurate three-dimensional (3-D) micro-positioning system was employed with the new nozzle to deposit maltose structures. 3-D architectures had been made by this method, the width of fiber in which is about 120 μm. The results show that this method provides a possibility to construct 3-D scaffolds with tissue-scale features (i.e., 10-100 μm) without bad influence on the biological activities.
2009年S1期 v.14 116-119页 [查看摘要][在线阅读][下载 411K] [下载次数：27 ] |[网刊下载次数：0 ] |[引用频次：3 ] |[阅读次数：0 ] - 陆伟;林峰;韩建栋;齐海波;晏耐生;
In electron beam selective melting process, powder pushed-away phenomena and uneven temperature field are two main obstacles, which are greatly associated with the electron beam scan mode. In this paper, various scan strategies, including iterative scan mode, reverse scan mode, interlaced reverse scan mode, randomized block scan mode, and constant length scan mode, are investigated. The analyses for each scan strategy are presented based on the influence to the temperature field over the formation zone and the powder pushed-away phenomena. The most promising strategy, interlaced reverse scan mode, is approved by the ANSYS simulation and a two-dimensional scan experiment. The result shows interlaced reverse scan mode can improve the uniformity of the temperature field and reduce the powder pushed-away phenomena.
2009年S1期 v.14 120-126页 [查看摘要][在线阅读][下载 499K] [下载次数：89 ] |[网刊下载次数：0 ] |[引用频次：7 ] |[阅读次数：0 ] - 张宇;刘红武;
This paper studies engineering applications of rapid prototyping (RP) technology in die making of diesel engine. On demand of product development and die making of, an integrated system of reverse engineering and rapid prototyping (RE/RP) for engineering application is constructed, and effective application of RP technology in die making is thus realized. Taking the casting die for clutch house of diesel engine as an example, this paper studied the engineering application of laminated object manufacturing (LOM) technology in rapid die making and discussed related technologies as parameter setting of temperature and pressure in heat pressing, the matching of laser power and cutting speed of laser, and layout and post treatment of the prototype in RP technology. The casting die manufactured with LOM technology has satisfactory lifetime and is successfully used in 100 rough castings of clutch house for diesel engine. The manufacturing cost for the die is decreased and the production period is shortened.
2009年S1期 v.14 127-131页 [查看摘要][在线阅读][下载 301K] [下载次数：162 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 张鹏;于静泊;郑雄飞;
Laser forming is a highly flexible sheet metal forming technique. In laser forming along curved irradiation paths, the heated zone is bigger and the effects of the processing parameters on the deformation are complex. The deformation behaviors of laser forming of ring sheet metals have been investigated from the thermal-mechanics analysis by the finite element (FE) simulation based on the proposed finite element method model. The effects of ring central angle and scanning path on deformation of ring sheet metal were investigated. The results are as follows: (1) in comparison with the laser bending along linear path, the marked third point has two peak temperatures during the laser forming process along curved path; (2) the forming process fluctutes continuously and the sheet edge is warped because the rigid-ends effect due to the restriction of sheet; (3) when the ring central angle increases, the displacement difference of the marked three points decreases and then increases, and the warped curvature of sheet edge decreases; (4) when the laser beam diameter increases, the displacement difference of the marked three points decreases and the warped curvature increases.
2009年S1期 v.14 132-136页 [查看摘要][在线阅读][下载 585K] [下载次数：60 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 钱波;张李超;史玉升;刘冰;
This paper studies the practical generation of Voronoi diagrams for multiply-connected planar areas bounded by line segments. The core of the algorithm was calculating Voronoi polygon of every Voronoi object in planar areas independently. The main approach had two steps. The first step was calculating all relevant bisectors of every Voronoi object. The second was combining obtained bisectors into completed Voronoi polygons individually. All code was implemented in Visual C++ platform. The resulting code was extensively tested in real-world data and its practical running time grew only linearly. Three statistical CPU-consumption charts had been drawn with the Voronoi diagrams computation data, and compared with other published codes for computing Voronoi diagrams. The algorithm was applied to compute offsetting of slice area consisting of large-scale line segments for the selective laser melting (SLM) trajectory scanning technology which is a kind of rapid prototyping (RP). The experimental results of offsetting for slice area based on Voronoi diagrams show that the approach is effective and simple for polygon offsetting problems. The method is helpful to those offsetting work and can provide more effective offsetting solution.
2009年S1期 v.14 137-143页 [查看摘要][在线阅读][下载 455K] [下载次数：124 ] |[网刊下载次数：0 ] |[引用频次：4 ] |[阅读次数：0 ] - 李洪友;江开勇;郭隐彪;彭云峰;
Electroforming is a specialised electroplating process for the manufacture of precision metal parts and mold tooling. Because it can simplify technical process and shorten molding cycles, electroforming is also a rapid manufacturing technology. Compared with direct and unipolar pulse current, bipolar pulse current in electroforming can obtain fine structure and grain size as well as surface leveling, resulting in better precision and surface finish. In this paper, bipolar pulse current electroforming is introduced. The influencing parameters such as electrolyte parameter, additives, current density, pH, temperature, and pulse parameters have been studied by experiments. Experiments on nickel electroforming in molds and dies have been done. The results indicated that bipolar pulse current electroforming could improve the quality and precision further, while reducing internal stress.
2009年S1期 v.14 144-148页 [查看摘要][在线阅读][下载 615K] [下载次数：62 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - 郑炜;郑珲;廖锐;
A new process and technology of rapid prototyping for a μ-micro motor is presented as a nontraditional machining and an advanced manufacturing technology (AMT) to be realized by using masks, including the operation principle of the motor, structure design, technique, driven circuit, and quality examination with Raman spectrum. The μ-micro motor is fabricated by the micro electro-mechanical systems (MEMS) process, the structure design must be considered to fabricate or assembly the parts during machining the motor in the meantime. The research proved that integration of IC (integrated circuit) process and MEMS using masks is effective in obtaining the rapid prototyping manufacturing of the μ-micro motor. With the mature technique to fabricate the motor, there are advantages to produce the motor in short time and with lower cost than before. The motor is a common power source of micro machines in military and civilian applications, for example, applied to micro robot, micro bio medicine, and micro machine. The size of the motor is 190 μm in maximum diameter by 125 μm in height that is bulk machined in array with the number of hundreds of micro motors on a substrate.
2009年S1期 v.14 149-153页 [查看摘要][在线阅读][下载 231K] [下载次数：105 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 胡围围;康进武;黄天佑;
Direct laser metallic powder deposition technique is widely used in manufacturing, part repairing, and metallic rapid prototyping. The ability to predict geometrical accuracy and residual stress requires an understanding of temperature distribution during the deposition process. This study presents a numerical model of three-dimensional transient heat transfer in a finite model heated by a moving laser beam. Thermal phenomena in the process were investigated. The complex solid-liquid problem and latent heat of fusion were treated by means of equivalent thermal conductivity and modified specific heat, respectively. Using method of birth and death of elements, the growth of additive layers and the shape of melt pool were obtained. The effect of processing parameters such as absorbed power, travel speed, and preheated temperature on melt pool sizes and cross-section of deposited layer profile was studied. The results show that the melt pool sizes increase with absorbed power and decrease with travel velocity. In addition, the preheated temperature contributes less to the melt pool size. The results are generally in a good agreement with experiments in published literature.
2009年S1期 v.14 154-159页 [查看摘要][在线阅读][下载 705K] [下载次数：54 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - Soshu Kirihara;Daisuke Sano;Masaru Kaneko;
Photonic crystals with three-dimensional dielectric structures were fabricated to control terahertz waves effectively by using micro-stereolithography of a CAD/CAM process. The photonic crystals with a diamond structure composed of acrylic lattice with nanosized alumina particles were fabricated. Dense alumina structures were obtained by successive dewaxing and sintering in an air atmosphere. The electromagnetic wave properties of these samples were measured by using a terahertz spectroscopy device. The micro periodic structures exhibited perfect band gaps in the terahertz range. To control terahertz waves, micrometer sized electromagnetic devices for cavities, filters, and antennas will be necessary.
2009年S1期 v.14 160-163页 [查看摘要][在线阅读][下载 544K] [下载次数：54 ] |[网刊下载次数：0 ] |[引用频次：1 ] |[阅读次数：0 ] - Svetan Ratchev;Michele Turitto;Joel Segal;
This paper introduces a non-assembly manufacturing case with microstereolithography technology. The design and manufacturing process of a pneumatic thrust bearing is described, and a special tessellation method is developed to further improve the capability of the manufacturing system thus bigger products can also be easily manufactured. Implemented in a layer-by-layer fashion, stereolithography has been used for the rapid manufacturing of complex devices, and it avoids the expensive assembly process in the traditional manufacturing. This paper presents that microstereolithography can produce high-resolution products with intricate details, small openings, and smooth surfaces. The potential of the microstereolithograhy technique is explored for the rapid manufacturing of small and complex objects.
2009年S1期 v.14 164-167页 [查看摘要][在线阅读][下载 488K] [下载次数：45 ] |[网刊下载次数：0 ] |[引用频次：9 ] |[阅读次数：0 ] - 吕雪松;LEE Yoonjae;EVANS Julian R G;PARINI Clive G;
Extrusion freeforming can be used for the rapid prototyping of millimeter-wave electromagnetic bandgap (EBG) structures. In this work, an alumina-polymer paste with a relatively high volatility solvent (propanol) was used and the characteristics of the ceramic paste, particularly the rheological features are described. The advantage of high volatility solvent is that the viscosity and elastic modulus of the paste are increased sharply as the solvent evaporates. Thus, the rigidity of the extruded filament is quickly increased as a small amount of solvent evaporates. Finally, by employing this procedure, different EBG structures such as 2-D, 3-D woodpile and aperiodic structures were fabricated and their bandgaps were measured. The experimental results show that extrusion freeforming is a relatively simple and easy method to fabricate these woodpile structures with a bandgap in the 90-110 GHz region.
2009年S1期 v.14 168-174页 [查看摘要][在线阅读][下载 984K] [下载次数：81 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：0 ] - 李炯;杨伟东;刘丽冰;颜永年;
In this paper, by studying the different kinds of jetting system in patternless casting manufacturing (PCM) technique, the different types of jetting mode are tested which affect whether PCM process can be done successful. The two different kinds of jetting device and their control circuits are designed based on which the relationship between the jetting system and amount of the catalyst flow is analyzed. The experiments show that the amount of the catalyst by using discrete jetting mode in the discrete jetting device is much lower than that by using continuous jetting mode in the discrete jetting device and in the continuous device when the pressured is fixed. At the same time, in the discrete jetting mode the amount of the catalyst flow can also be changed by adjusting the pulse frequency and its duty cycle, this can ensure the strength of the sand mould. The flow of catalyst in this discrete jetting device can match the scanning speed of the jetting device in real time which will improve the resolution and building precision of casting mould. When the amount of the catalyst jetting is too large, PCM process will fail.
2009年S1期 v.14 175-179页 [查看摘要][在线阅读][下载 251K] [下载次数：66 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 杨伟东;颜永年;张人佶;刘丽冰;
The patternless casting manufacturing (PCM) technique, which adopts a new concept of double scanning method, combines the principle of discreteness and deposition with resin-bonded sand technique. This paper is to evaluate the dimensional accuracy of sand mould on PCM. The two important factors-the liquid penetration rule in the space of particles and the shape and dimension of the agglomeration unit body, which influence the process parameters such as scanning speed, layer thickness, liquid flux on dimension accuracy, and surface qualities, were investigated systematically, thus the theoretical basis for these parameters was provided. Experiments on rapid manufacturing of sand mould were carried out, and the results of the free penetration and the constraint penetration well verified the relationship of the two factors and the process parameters.
2009年S1期 v.14 180-185页 [查看摘要][在线阅读][下载 315K] [下载次数：89 ] |[网刊下载次数：0 ] |[引用频次：4 ] |[阅读次数：0 ] - 靳晓曙;杨洗陈;
Off-line programming provides an essential link for CAD/CAM. This paper introduced the principle of developing off-line programming system for laser re-manufacturing. Task and information flow of off-line programming for laser re-manufacturing robot was analyzed and the software structure of off-line programming based on commercial CAD software was constructed. The off-line programming system developed in this study includes 3-D solid model design, direct slicing for obtaining path data, graphical simulation of the robot and its workcell, kinematic model of the robot, motion planning, and creation of the control program for manufacturing process. The CAD software was used to design models of robot, workpiece, coaxial nozzle, and workspace. Through the application programming interface provided by the CAD software, the VC++ and ATL were chosen to develop such modules as direct slicing for obtaining path data, path planning, process specification, and control program automatic generation. The FANUC Roboguide software was used to realize graphical simulation. By direct slicing, the position and orientation data of robot end-effector was determined. The results show that the proposed system can be applied in laser re-manufacturing robot for manufacturing operations.
2009年S1期 v.14 186-191页 [查看摘要][在线阅读][下载 975K] [下载次数：125 ] |[网刊下载次数：0 ] |[引用频次：14 ] |[阅读次数：0 ] - 王维;尚晓峰;
The functionally gradient material laser rapid prototyping system is developed based on the increasing material manufacture idea of the rapid prototyping. The system hardware is composed of a 5 kW CO2 laser, a three-dimensional numeric control table, a three-stock-bin coaxial powder delivery device, and an integration operation control desk. The system software is composed of the CAD slicing and scan filling module, materials component distributing design module, and hardware equipment integration drive module. The real time change proportion allocation technique of three metal powders, powder uniform mixing technique, and coaxial powder delivery technique are studied. According to the principle of the output powder cumulative volume invariable in unit time, the real time powder allocation formulae are deduced. The design method of the materials component distributing regularity in the part entity is studied. The gradient change regularity of the face gradient, line gradient, and point gradient is studied. A sort of the file layout of integrating material information and geometry information is brought forward.
2009年S1期 v.14 192-199页 [查看摘要][在线阅读][下载 360K] [下载次数：141 ] |[网刊下载次数：0 ] |[引用频次：3 ] |[阅读次数：0 ] - 王志坚;仉安娜;尚晓峰;
The metal powder direct and rapid prototyping technology is one of the most developing methods in the laser rapid prototyping technique. The coaxial powder delivery system is the key technique. The purpose of this paper is to introduce a new type of coaxial powder delivery system and simulate the metal powder and shield gas flow in the powder nozzle. 2-D and 3-D model of the new coaxial powder delivery system are established. Then gas-solid two-phase flow model and the k-ε turbulent model are selected to simulate the flow of metal powder in powder nozzle. The Euler-Lagrange method is used in the simulating computation. The results show that the new coaxial powder delivery system has stable performance, uniform powder flux, high cooling efficiency, and long useful life.
2009年S1期 v.14 200-205页 [查看摘要][在线阅读][下载 473K] [下载次数：104 ] |[网刊下载次数：0 ] |[引用频次：5 ] |[阅读次数：0 ] - 李晓燕;
Experiment of rapid prototyping (RP) is a multi-level and multi-factor problem with long process cycle. As powder-based RP method, three dimensional printing (3DP), and selective laser sintering (SLS) are the most prominent RP methods for their flexibility in material selecting. The research of 3DP process shows that much experiments work can be greatly decreased by the method of uniform design with restricted mixtures for RP products' performance to its forming material. Then, according to backward regression methods, the binomial and inverse terms nonlinear regression equations were set up by statistic analysis and computation. Together with evaluation function method, multi-object optimization model for performance of products to the powder mixtures was developed, and the optimization problem was solved by software MATLAB. After that, the optimum results were solved and tested by experiment with the same condition as before. Differences between the calculation results and testing results, which including product's density, compression strength, surface evaluation, and deformation in three dimensions, are less than 10%, and have the same error direction. Uniform design method for regression and optimization was proved to be an excellent method to obtain optimum results for multi-level and multi-factor experiments of RP and other process which have a long processing cycle.
2009年S1期 v.14 206-211页 [查看摘要][在线阅读][下载 229K] [下载次数：64 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 董晓丽;李新亚;单忠德;刘丰;
Direct milling of sand molds is an important development in rapid manufacturing of sand molds. Direct milling is an effective method for manufacturing single or small batches of cast parts. This paper describes experimental investigations to find sand blocks with the appropriate strength, to describe wear patterns of different tools (high-speed steel (HSS), carbide, and polycrystalline diamond (PCD) tools), and to analyze sand mold cutting mechanisms. The results show that the PCD tool outperformes the other tools in terms of tool life. Average flank wear and micro-tipping are the dominant tool failure modes in the sand mold milling process. With a flank wear limit of 0.3 mm, the PCD tool works continuously for about 70 h under the experimental conditions. The experimental results show that the cutting mechanism for direct milling sand molds differs from metal cutting.
2009年S1期 v.14 212-215页 [查看摘要][在线阅读][下载 462K] [下载次数：157 ] |[网刊下载次数：0 ] |[引用频次：19 ] |[阅读次数：0 ] - 王霏;江开勇;徐西鹏;
This paper presents the gel casting of metal powder by agar gelation through mold decomposed injection sculpture (DIS) process:verifying the feasibility and improving the processing parameters to prepare stable metal slurry and strong green body. The optimal processing parameters were achieved after investigating the effects of these parameters such as temperature, agar content, dispersant concentration, and solid volume loading. The rheological behavior of metal slurry and the character of formed green body were also investigated. The mixture and dispersion mechanism of metal slurry as well as the consolidation forming and sintering technology of green body were studied based on analysis of experimental results. The results show that the optimal pH range is 8.5-9.5 with the grain size distribution of 2-30 μm and 55% solid suspension, which can be prepared by adding proper dispersant (Polyvinyl Alcohol). The agar and dispersant content has great effect on the properties of slurry. When 1.0 wt.% dispersant and 0.7 wt.% agar content (referred to dry solid) are adopted, stable metal slurry with viscosity less than 1 Pa·s and green body with bending strength of 2.7 MPa are obtained. The sintered bodies with uniform structure, relative density of 90%, and yield strength of 150 MPa are prepared at 1300℃/30min in vacuum. This process can be applied in rapid prototyping of complex shape metal products such as rotor blades.
2009年S1期 v.14 216-222页 [查看摘要][在线阅读][下载 980K] [下载次数：61 ] |[网刊下载次数：0 ] |[引用频次：2 ] |[阅读次数：0 ] - 黄小毛;叶春生;莫健华;刘海涛;
This paper presents a robust algorithm to generate support for fused deposition modeling (FDM). Since many flaws appear in most stereo lithography (STL) models, this algorithm utilizes slice data as input. A top-down approach was used to calculate the support slice layer by layer. The generation algorithm was described in detail including the slice grouping, oriental bounding box (OBB) calculation, offsetting, and Boolean operations. Several cases are given to validate the efficiency and robustness of the procedure. The algorithm provides necessary support not only for hanging surface but also for hanging vertexes and edges with O(n) time complexity, where n is the number of layers. The algorithm fully utilizes the parts' self-support ability and reduces support volume to the maximum extent. This slice data based algorithm has the same efficiency as the STL based algorithm but is more stable, which significantly enhances the robustness of the support generation process.
2009年S1期 v.14 223-228页 [查看摘要][在线阅读][下载 551K] [下载次数：172 ] |[网刊下载次数：0 ] |[引用频次：32 ] |[阅读次数：0 ] 下载本期数据