Advanced Materials Research Vol. 939

Abstract: At present, quite a lot of enterprises, small or medium-sized, are engaged in developing the various necessaries of livelihood. And, the forming processes are generally adopted for the methods of parts manufacture. Though various forming technology progress rather well, but the warm working process often cannot obtain fine finished products in the process of manufacturing. The warm working process still needs more adequate techniques. This study is focused on the analyzing of the warm forging-flaring process of brass tube, and the improving of the die design and the working procedures. In this paper, two sets of forging and flaring die are designed for experimental works. The results of simulation are compared with the experiments, the formability of brass tube showed a good agreement. Therefore, we suggest a multi-pass of forging process instead of single-pass process. The stress distributions and loading history in forming processes are also assessed in details. The method used in this study is available in the relative warm forming processes and die design. It is helpful to increase the additional value of products and promote the level of competition in manufacturing industry.

Abstract: This study has established the equivalent CAE model of a loading large-scale gear reducer for simulating and evaluating the dynamic responses, including the rotation speeds of shafts and meshing forces of gear pairs, in the time and frequency domains by using MSC.ADAMS. The transient response results were compared with measurement data under the practical application to verify reliability and equivalence of the constructed CAE model. The proposed approach and model may be served as the basis to access the transmission performance, vibration analysis, failure diagnosis and even structure improvement for the large gear reducers.

Abstract: The slot coating process in the production of polymer films has a wide range of applications. However, the process cannot be systemized. This study used the computational fluid dynamics software Polyflow to analyze the slot coating process and investigate the influence that the process parameters have on the characteristics of thin-film coating to reduce the time and cost consumed in the experimental methods. The rheological characteristics of the non-Newtonian fluid used in this study were first identified by conducting experiments, and then configured in the simulation software for fitting with mathematical models. In addition, the models of the slot coating process were constructed, and the Arbitrary Lagrangian-Eulerian (ALE) calculation methods were then used in the Polyflow software. The simulation results were then compared to the experimental results and the findings reported in relevant literature, to determine the influence that the process parameters have on the characteristics of thin-film coating. The simulation results were represented graphically in a coating window plot. The comparison results indicate that the viscosity-shear rate characteristic of the material in the shear rate range of optical film coating is an excellent fit for the Cross Law. When the coating speed is too high or the amount of fluid supply is insufficient, phenomena such as break lines, uneven thickness, and air entrainment can occur.

Abstract: Data-mining methods using hierarchical and non-hierarchical clustering are proposed that will help engineers determine appropriate drilling conditions. We have constructed a system that uses clustering techniques and tool catalog data to support the determination of drilling conditions for printed wiring boards (PWBs). Variable cluster analysis and the K-means method were used together to identify tool shape parameters that have a linear relationship with the drilling conditions listed in the catalogs. The response surface method and significant tool shape parameters obtained by clustering were used to derive drilling condition decision equations, which were used to determine the indicative drilling conditions for PWBs. Comparison of the conditions recommended by toolmakers demonstrated that our proposed system can be used to determine the drilling condition for PWBs. We carried out the drilling experiments in accordance with the catalog conditions and mining conditions, and estimated the board temperature around a drilled hole, the drilling forces, and the roughness of the drilled hole wall.

Abstract: In this report, an approach to calculating meshing frequency through the rotational speed of the sun gear, ring gear, and carrier of a planetary gear set is proposed. The proposed method includes a convenient contour map of the rotational speed of each component of the planetary gear sets and the meshing frequency. This contour map is used to estimate the relationship between the numbers of teeth, the rotational speed, and the meshing frequency. The results of experiments measuring acceleration via an accelerometer attached to the edge of a carrier clearly showed the meshing frequency and rotational component frequency at each rotational speed. A comparison of the acceleration at each meshing frequency shows that the vibrational level can be reduced by modifying the specifications of the planetary gear set (the number of teeth, number of pinions, radius of the carrier, etc.). The proposed method is an effective means of reducing vibration and noise in planetary gear sets.

Abstract: This study applies the finite element method (FEM) to predict maximum forging load, billet volume and effective strain in near net-shaped helical-bevel gear forging. Finite element analysis is also applied when designing the near net-shape of a helical-bevel gear, a reverse forming approach to acquire the initial dimensions of the billet based on the forward forging of the helical-bevel gear. Maximum forging load, billet volume and effective strain are determined for different process parameters, such as modules, number of teeth, helix angle and workpiece temperature of the helical bevel gear forging, using the FEM. Finally, the prediction of the power requirement and billet dimensions for the helical-bevel gear warm forging are determined.

Abstract: Traditional dental impression approach is not applicable to most of the oral and craniofacial trauma patients. Without a physical model, it is not easy to evaluate a patients fracture and occlusion, limiting the treatment process. Especially, the accuracy of the maxillofacial model for occlusion evaluation needs to meet strict clinical demands. Therefore, in this research, we attempted to use computed tomography (CT), without damaging the oral and craniofacial tissues of patients, together with image processing and Rapid Prototyping (RP) technique to obtain physical oral and maxillofacial models with high accuracy. Initially, a set of procedures of generating maxillofacial model was developed. CT images were segmented and converted to a CAD file by a commercial medical image processing software. RP technique was used to fabricate maxillofacial model. After comparison, the deviations were greater than clinical demands of less than 1 mm. After analyzing the sources of errors, issues of CT slice thickness, images threshold selection and editing, and RP fabrication were investigated to improve the accuracy. As a result, updated standard procedures were suggested to obtain RP maxillofacial models with higher accuracy. The improved average deviation can be reduced to 0.22 mm. The biological RP models with high accuracy generated in this research can be used to improve success rate and safety in a surgery, to reduce complications after the surgery, and to decrease the time and cost of treatment.

Abstract: The directive is to develop a new type of cross-flow fan for cooling electronic devices. First, the module is based on the 60X60X6mm fan and attempts to use several parameters to enhance the fan’s performance. The parameters considered here include blade number, angle of the blade, impeller diameter, divergent structure, and outlet area. Both numerical and experimental analyses are carried out on the cross-flow fan which was oriented horizontally. The ANSYS Fluent software is used in a 2D simulation to predict the heat transfer coefficient and the flow fields. Next, the flow and acoustic noise measurements are carried out at different parameters with the aid of AMCA and semi-anechoic chambers. The results show that when the outlet vent size is 70% of fan outside diameter the outcome is an enhanced fan performance of 12%. The optimal number of blades is 37. A block is inserted below the fan blade to improve the fan performance by 8%. The numerical and experimental values of air flow were plotted and found to be consistent. In summary, this study provides a systematic process to develop a cross-flow fan that can meet the requirements for thin and light laptop computers.

Abstract: In this paper, it based on the ideal gas conditions in the Maxwell velocity distribution and considering only the elastic collisions between gas molecules to study the distribution of gas molecules in the gravity field as a means of computer simulation. The simulation results show the process of molecular movement and distribution patterns. And it can be found that the distribution of gas molecules in the gravity field distribution is determined by the frequent collisions between molecules and it has nothing to do with the velocity and the initial position of molecules. In addition, the simulation also reveals the Boltzmann distribution law is a statistical regularity in terms of the large number of particles. The ideal gas elastic collision simulation software can increase intuitive awareness of students on the knowledge, and to provide an effective adjunct to consolidate what they have learned.

Abstract: Bicycle becomes famous transportation as efforts cut greenhouse gas emission. Comfortable, less injured, and less energy are the requirement of bicycle that urban communities wanted. Seat tube angle (STA) is an angle formed between seat tube and chain stay, which has influences on the above requirement. The objective of this study is to investigate the effect of varying seat tube angle (STA) on the muscle tension leg riders during cycling. This study used changeable frame bicycle into several STA. A total five cycling trials with body mass index 21-25, were conducted at seventeen STA’s position (form 62° until 78°). Muscle tension leg was measured before and after cycling by using leg dynamometer. Oxygen consumption (VO2) and heart rate (HR) data were also collected during cycling at 6 minutes and will be converted to paddle energy. Through this study was found that muscle tension leg rider decreasing with the increasing STA. However, after STA of 66°, the muscle leg tension increasing respecively. The smallest muscle tension leg was 21,4 Kg at 66° STA. At the same position, pedal energy showed 7.148 Kcal which was the smallest result as well. From these study found, that 66° STA also had less muscle tension leg and paddle energy during cycling.