Ying-Chien Tsai

Surface Geometry of Straight and Spiral Bevel Gears

The fundamental geometrical characteristics of bevel gears have been discussed in this study. The mathematical modeling of the tooth surface geometry of bevel gears can be developed based on the basic gearing kinematics and involute geometry along with the tangent planes geometry. The parametric representations of the spherical involute and the involute spiraloid, which are the tooth surface geometry of straight bevels and spiral bevels, respectively, have been derived in this paper. This study may provide some fundamentals for computer numerical controlled manufacturing of bevel gears.

A method for calculating static transmission errors of plastic spur gears using FEM evaluation

Abstract There are many ways to calculate the static transmission errors of steel gears, but none is developed for plastic gears. Since the Youngs modulus of the plastic material is lower than that of steel by two orders, the effects of large tooth deflection on the static transmission errors of plastic gears become significant. A multi-tooth contact analysis using finite element method for calculating the static transmission errors of plastic spur gears is established to compare with the existing method for steel spur gears. According to the comparison results, a modification of the existing method is proposed for plastic spur gears and verified by the same finite element contact analysis.

Design of high-contact-ratio spur gears using quadratic parametric tooth profiles

In order to obtain high contact ratios, the addendums of spur gears with involute profiles should be increased. This will increase the root stress sensitivity and the minimum tooth number of gears without undercut. This paper proposes a method of designing high-contact-ratio spur gears using quadratic parametric tooth profiles for the shorter addendums and no undercut. A design procedure is developed and a simplified derivation of the mathematical model of parametric tooth profiles is presented. The tooth root stresses and the static transmission errors are shown to be lower than those of high-contact-ratio spur gears with involute profiles, but the contact stresses and the wear height indices are traded off. Some examples are given to demonstrate the potential of this method.

Workspace synthesis of 3R, 4R, 5R and 6R robots

Abstract In a previous study [Y. C. Tsai and A. H. Soni, Mech. Mach. Theory19, 9–16 (1984)], the regional and orientational structures of a general 6R robot were analyzed as separate 3R assemblies and optimum kinematic parameters for these structures were obtained. This paper utilizes the above results to develop design methodologies for 3R, 4R, 5R and 6R industrial robots. For a given set of design conditions involving full description of the accessible region and a type of robot, the paper presents in a stepwise manner a procedure to obtain the design data involving link-lengths, relative orientations of the axes of the revolute pairs and the range of angular displacements at each of the joints. The method is illustrated by an example of a synthesis of 6R robots.

A study of a design and NC manufacturing model of ball-end cutters

Abstract The study of the design and manufacturing of special milling processes is important in the development of a mold with complex curved surfaces. In this paper, the analysis method integrates design, manufacturing and numerical simulation to obtain a suitable manufacturing model of the design and NC manufacturing of ball-end cutters. Furthermore, a helical edge curve with constant helix angle on the cylinder and the ball-head, the exact solution of the helical groove cross-section equation, and the mathematical model of the grinding wheel cross-section, are also presented in this study. Results of the numerical simulation and the compensation of NC manufacturing show that the manufacturing of ball-end cutters is capable of being carried out using a two-axis NC machine. These studies provide excellent references for the NC manufacturing of ball-end cutters.

Postweld-shift-induced fiber alignment shifts in laser-welded laser module packages: experiments and simulations

The fiber alignment shifts induced by the postweld shift (PWS) in laser-welded transistor outline (TO)-Can-type laser module packages were studied experimentally and numerically. The PWS-induced fiber alignment shifts were quantitatively determined by four geometrical parameters, namely: 1) the lateral shift (r); 2) the position angle (/spl alpha/); 3) the swing angle (/spl theta/); and 4) the tilt angle (/spl psi/). The measured coupling powers in laser module packages before welding, after welding, and after a welding compensation clearly confirmed with the measured fiber alignment shifts determined by the dominant parameters of the r and /spl alpha/ that the fiber shifts due to the PWS could be realigned back closer to their original optimum position after applying a welding compensation, and, hence, the coupling power loss due to the PWS could be regained. A coupled thermal-elastoplasticity model of finite-element-method (FEM) analysis was performed to evaluate the effects of PWS on fiber alignment shifts in laser module packages. The measured fiber alignment shifts determined by the dominant parameters of the r and /spl alpha/ were in good agreement with the numerical calculation of the FEM analysis. In this study, the combination of the experimental and numerical results have significantly provided a practical design guideline for fabricating reliable laser-welded TO-Can-type laser module packages with a high yield and high performance for use in low-cost lightwave transmission systems.

A novel fiber alignment shift measurement and correction technique in laser-welded laser module packaging

A novel measurement and correction technique employing an ultra-high-precision laser displacement meter (LDM) with a 20-nm resolution to probe the postweld-shift (PWS)-induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded laser module packaging can be quantitatively determined by four parameters: the lateral position (r), the position angle (/spl alpha/), the swing angle (/spl theta/), and the tilt angle (/spl psi/). Further studies show that the deformation of the lateral shift and the position angle are the dominant mechanisms that determine the fiber alignment shifts induced by the PWS. This clearly indicates that the PWS can be quantitatively corrected timely by applying a single weld spot on the negative lateral shift and the position angle to compensate for the fiber alignment shifts. In comparison with previous studies of the PWS correction by a qualitatively estimated technique, this LDM technique has significantly provided an important tool for quantitative measurement and correction to the effect of the PWS on the fiber alignment shifts in laser-welded laser module packaging. Therefore, the reliable laser modules with high yield and high performance used in low-cost lightwave transmission systems may be developed and fabricated.

Investigation and Comparison of Postweld-Shift Compensation Technique in TO-Can- and Butterfly-Type Laser-Welded Laser Module Packages

The postweld-shift (PWS) compensation techniques employing a laser displacement meter (LDM) in the transistor outline (TO)-Can-type laser-welded laser module package and a high-magnification camera with image capturing system (HMCICS) in the butterfly-type laser-welded laser module packages are quantitatively investigated and compared. The results show that the fiber alignment shifts due to the PWS can be aligned back closer to their original optimum position after applying the proposed compensation techniques, and hence the coupling powers loss due to the PWS could be regained significantly. Comparing with the measured coupling power and the PWS, the results show that the PWS are in the ranges of 0.2-1.6 mum and 2.1-4.2 mum for the TO-Can- and the butterfly-type laser packages, respectively. The reason for having a larger PWS in the butterfly laser package is that the fiber ferrule is not solidly constrained in the vertical direction. In this paper, a coupled thermal-elasto-plasticity model of a finite-element method (FEM) analysis is employed to evaluate the PWS in the TO-Can- and the butterfly-type laser module packages. The simulated results are in good agreement with the measured results and these show that the PWS in the butterfly-type laser packages are larger than those in the TO-Can packages. A combination of the experimental and numerical results has provided a practical design guideline for fabricating reliable and high-yield laser-welded TO-Can- and butterfly-type laser module packages for use in lightwave communication systems

A study on the mathematical models and contact ratios of extended cycloid and cycloid bevel gear sets

In this paper, the general mathematical models of conjugate tooth profiles and constraints for bevel gear sets are presented. The tooth profiles of involute bevel gears, extended cycloid bevel gears and cycloid bevel gears are derived from the general mathematical models. The contact ratios for the extended cycloid and cycloid bevel gear sets are investigated. The design charts comparing the contact ratios of cycloid bevel gear sets with those of involute bevel gear sets are provided. They are useful for the engineers to design the bevel gear sets of high contact ratio.

A new scheme of fiber end-face fabrication employing a variable torque technique

A new scheme of optical fibers with different types of end-faces by applying different types of periodical variable torques to control the polishing pressure is proposed and fabricated. Two types of mechanisms, mechanical torque and electrical torque controls, are developed to generate different types of periodical variable torques. The mechanical torque control type is mainly designed for fabricating an elliptical-cone-shaped fiber end-face that can be used in efficient coupling between a laser diode and fiber with a coupling efficiency up to 83% (Lu et al 2007 Opt. Express 15 1434). The electrical torque control type is even more versatile for fabricating optical fibers or micro-probes with polygon pyramid end-faces that may have other potential applications, such as various kinds of micro-indenters. Both types of fiber end-faces can deliver satisfactory results with single-step fabrication, a high fabrication yield and sufficient optical coupling efficiency.