Automatic piloting in progressive dies using medial axis transform

Nowadays, progressive dies have a special role in various methods of sheet metal production. The design process, however requires a considerable amount of time and expertise. During the last three decades, different concepts of Computer Aided Progressive Die Design (CAPDD) have been studied all around the world. CAPDD involves various activities and among them piloting has been paid the least attention by researchers. In this paper, a mathematical model based on Medial Axis Transform (MAT) is introduced. This model is applicable to parts without suitable circular holes for direct piloting. The model analyzes the part geometry in order to find the best position for semi-direct and indirect pilots. It also optimizes the piloting system using minimum scrap strategy. A prototype software is also developed to automatically design auxiliary holes on the scrap part of the strip for piloting purposes. The input to the software is nesting template of the workpiece, which is composed of line and arc segments, and the output is the piloting system. The model is demonstrated through several industrial examples.     

光子晶体多组元缺陷态问题研究

缺陷态光子晶体可以用于制作良好的谐振器、偏振器、滤光器等光学器件,具有重要的应用价值。本文发展了光子晶体缺陷态问题的PG有限元界面问题计算方法,有效地处理了各种不同组元体系、几何结构、界面形状、材料属性以及模态的光子晶体缺陷态问题。数值结果表明,二组元结构单点缺陷对带隙的影响较小,只是使局部范围内的波继续传播而产生一条缺陷带,多点缺陷使一些特定范围内的波可以传播而产生多条缺陷带,线缺陷产生的影响较大,可以使整个禁带消失。结合线缺陷与点缺陷,波导结构中的侧点缺陷可以有效地应用于光子晶体阻带内诱导窄通带或在波导的通带内诱导非常窄的阻带。三组元结构引入了不均匀介质、复杂介质形状以及不同几何结构的缺陷态。通过计算与分析发现Ω₃区域的介质形状对结果影响比较有限,表面层越不光滑禁带越窄,n型缺陷态在TM模中的高频区域更容易产生禁带。对于TE模来说,n型与v型的缺陷态更容易产生禁带。     

Heteropoly acid supported on activated natural clay-catalyzed synthesis of 3,4-dihydropyrimidinones/thiones through Biginelli reaction under solvent-free conditions

Dihydropyrimidinones/thiones (DHPM’s) have been prepared by one-pot condensation of methyl acetoacetate, aldehydes, urea/thiourea in the presence of heteropoly-11-tungsto-1-vanadophosphoric acid, H₄[PVW₁₁O₄₀]?·?32H₂O, (HPV) supported on activated natural clay (HPVAC) under solvent-free reaction condition have been proposed. The DHPM derivatives were identified through elemental analysis and melting point measurements and characterized by FT-IR, ¹H-NMR, ¹³C-NMR spectroscopic methods.     

Viscous heating correction for thermally developing flows in slit die viscometry

In the thermally developing region, d _yy /dx| _y=h varies along the flow direction x, where _yy denotes the component of stress normal to the y-plane; y = ±h at the die walls. A finite element method for two-dimensional Newtonian flow in a parallel slit was used to obtain an equation relating d _yy /dx/ _y=h and the wall shear stress ₀ at the inlet; isothermal slit walls were used for the calculation and the inlet liquid temperature T₀ was assumed to be equal to the wall temperature. For a temperature-viscosity relation /₀ = [1+(T–T₀]^–1, a simple expression [(hd _yy /dx/ _y=h )/ _w0] = 1–[1-F _c(Na)] [M()+P(Pr) ·Q(Gz ^–1)] was found to hold over the practical range of parameters involved, where Na, Gz, and Pr denote the Nahme-Griffith number, Graetz number, and Prandtl number; is a dimensionless variable which depends on Na and Gz. An order-of-magnitude analysis for momentum and energy equations supports the validity of this expression. The function F _c(Na) was obtained from an analytical solution for thermally developed flow; F _c(Na) = 1 for isothermal flow. M(), P(Pr), and Q(Gz) were obtained by fitting numerical results with simple equations. The wall shear rate at the inlet can be calculated from the flow rate Q using the isothermal equation.Notation x,y Cartesian coordinates (Fig. 2) - , dimensionless spatial variables [Eq. (16)] - dimensionless variable, : = Gz(x)^–1 - dimensionless variable [Eq. (28)] - t,t ^* time, dimensionless time [Eq. (16)] - , velocity vector, dimensionless velocity vector - _x , velocity in x-direction, dimensionless velocity - _y , velocity in y-direction, dimensionless velocity - V average velocity in x-direction - _yy , ^* normal stress on y-planes, dimensionless normal stress - shear stress on y-planes acting in x-direction - _w , _w ^* value of shear stress stress at the wall, dimensionless wall shear stress - _w0, _w0 ^* wall shear stress at the inlet, dimensionless variable - , ^* rate-of-strain tensor, dimensionless tensor - wall shear rate, wall shear rate at the inlet - Q flow rate - T, T ₀, temperature, temperature at the wall and at the inlet, dimensionless temperature - h, w half the die height, width of the die - l,L the distance between the inlet and the slot region, total die length - T ₂, T ₃, T ₄ pressure transducers in the High Shear Rate Viscometer (HSRV) (Fig. 1) - P, P2, P3 pressure, liquid pressures applied to T ₂ and T ₃ - , ₀, ^* viscosity, viscosity at T = T ₀, dimensionless viscosity - viscosity-temperature coefficient [Eq. (8)] - k thermal conductivity - C _p specific heat at constant pressure - Re Reynolds number - Na Nahme-Griffith number - Gz Graetz number - Pr Prandtl number     

Optimum optics for die-to-wafer-like image mask inspection

The most annoying problem relating to the sensitivity of mask inspection systems is the encountering of false signals arising from nuisance defects. In order to overcome this problem, we have previously proposed a new algorithm for die-to-wafer-like image (D-to-WI) in real time. This paper describes the optimum mask inspection optics for the D-to-WI mask inspection. We examine the optimum mask inspection optics with numerical simulation for various numerical apertures (NAs) and partial coherence factors (σ) in these optics. The simulated result shows that the optimum mask inspection optics for the D-to-WI mask inspection has NA 0.9 and σ = 0.95 for an ArF-6%-phase shift mask (PSM) 260/260 nm line/space pattern on the mask plane, in which the 193 nm-ArF scanner has NA 0.93, σ = 0.92 − 0.92/0.3 annular illumination, reduction factor of ×4, and circular polarization incident light.     

纳米银焊膏烧结大功率LED模块的高温可靠性研究

介绍了一种加速老化试验模型对LED模块进行寿命预测。分别采用纳米银焊膏、锡银铜焊料、导电银胶作为芯片粘结材料。控制环境温度和正向电流,在特定的时间测量光输出。比较了不同粘接材料及环境温度对LED老化过程的影响,并针对老化过程进行分析推导,建立老化数学模型,对其进行寿命预测。试验结果表明,纳米银焊膏粘接的模块对温度的抗性最好,纳米银焊膏有潜力在未来固态照明、投影和其他高功率器件领域得到应用。     

摆辗成形后的摩托车启动齿轮三维塑性应变场的光塑性分析

本文叙述了采用聚碳酸脂材料模拟低碳钢和低碳合金钢一类金属的摩托车启动齿轮(下面陶称为端面齿轮)摆辗成形过程。运用光塑性法计算分析了氐形后的光塑性模型内部三维塑性应雯分布;对采用螺旋形轨迹和玫瑰线轨迹成形后的光塑性模型内部的三维塑性应变分布进行了分析比较。该方法已为摆辗最佳工艺参数的选择提供了有用的依据。     

Similarity Reductions of (2+1)-Dimensional Multi-component Broer-Kaup System

Painlevé property of the (2+1)-dimensional multi-component Broer-Kaup (BK) system is considered by using the standard Weiss-Kruskal approaches. Applying the Clarkson and Kruskal (CK) direct method to the (2+1)-dimensional multi-component BK system, some types of similarity reductions are obtained. By solving the reductions, one can get the solutions of the (2+1)-dimensional multi-component BK system.     

Attaching Planar Waveguide Dies to Aluminum Using Low-Stress Thermal Conductive Adhesives

We analyzed stress and heat transfer in attached planar waveguides. Die attaching adhesives were known to be the key to avoiding stress buildup in and dissipating heat from waveguides. When adhesives have a shear modulus of less than 1 MPa and a thermal conductivity of 2 w/mk, a 0.1-0.2-mm-thick layer of adhesive can eliminate stress-related effects and efficiently dissipate 30-50 mW/mm² of heat, even if aluminum is used as a substrate. Supersoft thermal conductive adhesives were thus developed and used to attach 60-mm-long AWG dies to aluminum with excellent results.     

A type of multi-component integrable hierarchy

A new isospectral problem is established by constructing a simple interesting loop algebra. A commutation operation of the loop algebra is as straightforward as the loop algebra ?_1. It follows that a type of multi-component integrable hierarchy is obtained. This can be used as a general method.