Kai Yong Jiang

Experimental Study of Bipolar Pulse Electroforming on Micro Optical Aspheric Mold Manufacturing

Compared with unipolar and periodic reverse pulse current electroforming, bipolar pulse current in electroforming is known to result 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 value, temperature and pulse current parameters have been studied on experiments. Experiments on nickel and nickel alloys electroforming on micro optical aspheric moulds have been done. The results indicated that bipolar pulse current could improve the quality and precision, reduce internal stress in micro electroforming.

Feature Line Extraction of the Triangular Mesh Model Based on Curvature and PCA

A method of feature line extraction from triangular mesh model is presented. Firstly, initial feature point is manually specified based on feature points extraction from triangular mesh model. Then begin with initial feature point, Principal Component Analysis (PCA) method is applied to analyze primary direction of special feature region of feature points. Search the feature point which is furthest from the center of mass in the primary direction and it is chosen as subsequent feature point. Iteratively, record the feature point sequence in order. Finally, use three order non-uniform B-spline curve to fit and construct feature line. The experimental results demonstrate that the proposed method in this paper is efficient.

Performance and Microstructure of TiN/Cu EDM Electrodes

This paper is to explore the feasibility of TiN/Cu-based composite materials as electrical discharge machining (EDM) electrodes.The tool wear ratio (TWR) of EDM electrode directly reflects the machining precision. To reduce the tool wear ratio(TWR) of Cu electrode in the EDM processing, Inorganic mixture of different content of ceramic materials TiN powder and Cu powder are prepared , then pressed and sintered into EDM electrodes.Experimental results show that: in the six batchs of experiments, the tool wear ratio (TWR) of 35%TiN/Cu electrode is the least, which is about 4.98%, much less than that of commercial copper electrode . The microstructures of the TiN/Cu electrodes after electrical discharge machining (EDM) as well are analyzed in this paper.

Foot Shape Reconstruction Based on a Monocular System Using Structured Light Projection

Reverse engineering has an increasing use in shoemaking process for rapid prototyping of shoe lasts. Foot shape reconstruction is one of the most important techniques in custom-made scheme. A system for reconstruction a foot shape from its 2D views using a coded structured light projection combining with the optical triangulation method is presented. A set of multiple gray coded patterns are projected to the target object through a projector and the distorted stripes patterns produced by its surface are captured by a digital camera. By adopting the optical triangulation method with the projector-camera parameters known in advance, the foot shape surface is reconstructed. The results show that the implemented system is able to reconstruct dense and precise 3D foot shapes.

Behavior of Microwave Heating of 316 Stainless Steel Green Body

This paper mainly introduces the mechanism of microwave heating: electric conduction loss, eddy current loss and arc discharge. The microwave heating behavior of 316 stainless steel powder body which made by gel casting was investigated in the paper. Experiments on different microwave power, powder particle size, and the content of auxiliary heating material showed that the smaller the powder particle size, the larger microwave power and auxiliary heating materials help 316 stainless steel body for sintering.

Complex Freeform Surface Measurement Based on Stereo Vision and Digital Phase-Shifting Techniques

In this paper, a method combining stereo vision and digital phase-shifting techniques is presented, which can measure the profile of complex freeform surfaces expeditiously and accurately. A chessboard is used to determine the camera parameters for the camera calibration of the system and the epipolar line rectification is executed based on the stereo calibration result. The stereo matching is processed with the combination of four-step phase-shifting and Gray code techniques, and the maximum probability method is proposed to remove the fringe order confusion problem between Gray code and phase shifting measurement. Bilinear interpolation method is also adopted to improve the speed and accuracy of stereo matching. Experiments were carried out with measuring a step gauge block and a shoe last model. Experimental results show that the measurement can be completed within 3 s for a measuring region of 640 mm × 480 mm, and the average measurement error is less than 0.054 mm.

An Experimental Study on Microwave Welding Technology of CuW to Cu Substrate

A preliminary study of welding CuW alloy to Cu substrate via microwave energy was investigated. Different proportions of CuW alloy powders were directly consolidated on clean Cu substrate surface. Then, they were heated at a certain temperature in a high vacuum microwave furnace. The results show that the appropriate conditions of 20°C/min heating rate, 900°C welding temperature and 5 minutes soaking time can weld CuW alloy to Cu substrate well, and the whole processing cycle is approximately 40 min. SEM morphologys reveal that the combination between CuW and Cu substrate is firm. The surface hardness of CuW alloy layer is 257HV, which is 2.5 times than that of Cu substrate. This technology reduces the processing cycle and has a positive significance on the surface modification and wear resistance of copper parts.

Experimental Study on Drying Process of Green Body in Gelcasting of Metal Part

In this paper, gelatin was selected as binder, sodium alginate as dispersant. The slurries with low viscosity and high solid loading were prepared by mixing two types of 316L stainless steel powders with different particle sizes in proper mass ratios. The freeze drying process was adopted to treat the wet green body. The results show that the slurry with a solid loading as high as 58 vol.% can be obtained by mixing 316L stainless steel powders with mass ratio of fine particles to coarse as 4:6, which has better fluidity and densification. The viscosity of the slurry is less than 1Pa•s. After the freeze drying process, the bending strength of green body reaches 11.15MPa, the drying shrinkage is decreased to 0.44%, and the generation of crack can be prevented. The study results provide some helpful references for further research in rapid manufacturing of complex metal part.

Effect of Laser Processing on Electroless Copper Deposition on Modified Plastic

Copper was selectively deposited on modified plastic without the palladium-catalyzed process. Laser direct writing was used to create the selective seeds.The effect of laser processing on the electroless copper deposition was investigated. Thus the morphologies and compositions of the sample before and after laser processing were investigated by means of sanning electron microscopy(SEM) equipped with an energy dispersive X-ray spectrometer(EDX) and X-ray photoelectron spectroscopy(XPS). The relationship between laser pulse frequency , scanning velocity and the topography of the deposited copper lines were also discussed

Study on Rollover Security Based on the Bus Middle Body Frame

Based on the middle body frame of a Half-integral bus which a bus manufacturer mainly produces in China, this paper discusses analyses and improvements for rollover security of the bus middle body frame with TRIZ methodology and TRIZ tools. On the basis of forming mechanism of bus rollover, a breakthrough point has been found from cause and effect relationship and function achievements aspect; some customized measures are therefore proposed. It focuses on the stiffness design of side pillars and the strength enhancement of soldering joints. Applying CAE analysis based on Ls-dyna, the results show that the deformation and deformation mode of the bus middle body frame have been greatly improved during bus rollover, which fulfills the requirements of the force of ECE R66 Rollover Security Regulations and validates the correctness of suggested measures.