Study of Alloy Springs with Magnetorheological Dampers for Vibration Isolator Device

Vibration is a factor that must be controlled during the manufacturing process; variation in workpiece dimensions often results in inaccuracies due to vibration. This study adopted a spring and electromagnetic-repulsion and magnetorheological damper that can absorb the energy of external vibrations and deduced the influential vibration factors. ANSYS was employed to determine the energy that could be absorbed by the vibration isolation device under machine vibration, and the Taguchi method of quality engineering was used to design the structure of the device (metal spring, wire diameter, and material). The usability of the product was examined for application in computer numerical control and traditional machines. The considered parameters of the magnetorheological fluid were density, the coefficient of elasticity, and Poisson’s ratio. The results indicated that spring wire diameter exerted the strongest effect on the device’s performance and that the electrical current provided to the damper could be buffered

Finite element analysis and die design of non-specific engineering structure of aluminum alloy during extrusion

[[abstract]]Aluminum extension applies to industrial structure, light load, framework rolls and conveyer system platform. Many factors must be controlled in processing the non‐specific engineering structure (hollow shape) of the aluminum alloy during extrusion, to obtain the required plastic strain and desired tolerance values. The major factors include the forming angle of the die and temperature of billet and various materials. This paper employs rigid‐plastic finite element (FE) DEFORM™ 3D software to investigate the plastic deformation behavior of an aluminum alloy (A6061, A5052, A3003) workpiece during extrusion for the engineering structure of the aluminum alloy. This work analyzes effective strain, effective stress, damage and die radius load distribution of the billet under various conditions. The analytical results confirm the suitability of the current finite element software for the non‐specific engineering structure of aluminum alloy extrusion

Finite element analysis of rim ring rolling forming of bicycle aluminum alloy

[[abstract]]The bicycle is not only a pollution-free method of transportation, but also has sport and recreation functions. Therefore, the bicycle attracted attention in now society gradually. This study uses the rigid-plastic finite element (FE) DEFORMTM software to investigate the plastic deformation behavior of a 7075 aluminum alloy workpiece as it is formed through a ring rolling die. This study systematically investigates the relative influences of ring rolling velocity, entering velocity, and workpiece temperature under various ring rolling forming conditions. The effective strain, effective stress, and workpiece damage distribution in the ring rolling process are also investigated. Results confirm the suitability of the proposed design process, which allows a ring rolling manufacturer to achieve a perfect design during finite element analysis

Study of Injection Molding Warpage Using Analytic Hierarchy Process and Taguchi Method

This study integrated Analytic Hierarchy Process and Taguchi method to investigate into injection molding warpage. The warpage important factor will be elected by Analytic Hierarchy Process (AHP), the AHP hierarchy analysis factor from documents collected and aggregate out data, then through the expert questionnaire delete low weight factor. Finally, we used Taguchi quality engineering method to decide injection molding optimized combination factors. Furthermore, the paper used injection pressure, holding pressure, holding time, mold temperature to analyze four factors, three levels Taguchi design data. Moreover, the paper discussed the reaction of each factor on the S / N ratio and analysis of variance to obtain the best combination of minimal warpage

Vibration characteristics and modal analysis of a grinding machine

The machine industry has undergone several developments in the past years, and reducing the cost and time required for machine designing is important. In this study, the vibration characteristics of a precision grinding machine were obtained through experimental modal analysis and finite element analysis. The experimental modal analysis employed single point excitation, and the equipment used to determine the frequency response of the grinding machine comprised a hammer, an accelerometer, and a spectrum analyzer. In addition, the resonance frequency, damping factor, and modal shape of the grinding machine were determined. The natural frequency, modal shape, and interface stiffness were determined through finite element analysis. Finally, the theoretical model and the experimental modal analysis models were compared, and get closer to the actual situation of a model to conduct several times analysis. Thus, this paper presents a reliable and convenient method to study the characteristics of machine tools; this method can reduce unnecessary costs and find structural weaknesses in machine designs for improvement

以問題導向與混成學習為核心教學法應用於工具機與模治具專題研究課程之教學實踐研究

[[abstract]]本教學實踐計畫試圖透過計畫主持⼈於⼯教系研究所⼯具機與模治具專題研究課程進⾏教學⾏動研究的⽅式，授課對象是 以博⼠班研究⽣課程，以過去計劃主持⼈在教學現場所發現之問題，例如：選課學⽣的個⼈專業背景不同，⼯具機產業不 斷的發展進步、培養多元的⼯具機與模治具技術、增進團隊合作能⼒等的專題研究課程。在執⾏本教學實踐研究計畫中， 研究團隊⾸先針對相關議題，透過⼯具機之專家學者的訪談與學界及產業界的從業⼈員之座談會蒐集彙整相關聯之議題， 成為本教學實踐研究課程研發之參考。教學實驗研究前，授試者先以前測，以獲取授試者之起點⾏為，以成為統計分析依 據；在執⾏研究的過程中，以問題導向與混成學習之教學⽅法進⾏教學實驗，研究團隊亦安排參與研究之學⽣進⾏實地參 訪，以獲取相關產業之實務經驗；在實驗研究後，再施⾏後測以確認教學實驗研究之成效。本教學實踐研究結果發現學⽣ 在⼯具機與模治具的專業能⼒，呈現顯著的進步。因此，本教學實踐研究計畫所設計的課程教學內容與⽅法對⼯具機與模 治具的相關課程內容有助於學⽣在修課時及國內⼤專校院課程教學設計與實施的參考。[[abstract]]This teaching practice plan attempts to conduct teaching action research by the project host in the machine tool and mold fixture special research course of the Institute of Engineering and Education. The teaching object is the doctoral graduate course, and the past plan host is at the teaching site. The problems discovered, such as: the different personal professional backgrounds of the elective students, the continuous development and progress of the machine tool industry, the cultivation of diversified machine tool and mold fixture technology, and the promotion of teamwork ability. When implementing the teaching practice research plan, the research team first focused on relevant topics, collected relevant topics through interviews with machine tool experts and scholars, and seminars with scholars and industry practitioners, and became the teaching practice research courses. Before conducting teaching experiment research, the examiner first conducts a pre-test to obtain the examiner’s initial behavior, which will become the basis of statistical analysis; in the process of research, the teaching experiment is carried out using problem based and hybrid learning teaching methods. The research team also arrange for students participating in the research to conduct field trips to gain practical experience in related industries. After the experimental research, post-test to confirm the validity of the teaching experimental research. The teaching practice research found that the students' professional abilities of machine tools and mold fixtures have shown significant progress. Therefore, the curriculum teaching content and methods designed by this teaching practice research plan are helpful to the relevant curriculum content of machine tools and mold fixtures for students in class, and the reference for the teaching design and implementation of domestic colleges and universities

Using the Taguchi Method and Finite Element Method to Analyze a Robust New Design for Titanium Alloy Prick Hole Extrusion

AbstractIn the process of prick hole extrusion, many factors must be controlled to obtain the required plastic strain and desired tolerance values. The major factors include lubricant, extrusion speed, billet temperature, and die angle. In this paper, we employed rigid-plastic finite element (FE) DEFORMTM software, to investigate the plastic deformation behavior of a titanium alloy (Ti-6Al-4V) billet as it was extruded through a conical prick hole die. We systematically examined the influence of the semi-cone angle on the prick hole die, the diameter of prick hole die, the factor of friction, the velocity of the ram and the temperature of the billet, under various extrusion conditions. We analyzed the strain, stress and damage factor distribution in the extrusion process. We used the Taguchi method to determine optimum design parameters, and our results confirmed the suitability of the proposed design, which enabled a prick hole die to achieve perfect extrusion during finite element testing

A Finite Element Investigation into the Changing Channel Angular Extrusion of Brass Alloy

Abstract. This study investigates a novel changing channel angular (CCA) extrusion process, in which high strains are induced within the billet by passing it through a series of channels of unequal cross-sections arranged such that they form specified internal angles. Using commercial DEFORM TM 2D rigid-plastic finite element code, the plastic deformation behavior of CuZn37 brass alloy is examined during one-turn and two-turn CCA extrusion processing in dies with internal angles of φ =90 o , 120 o , 135 o or 150 o , respectively. The simulations focus specifically on the effects of the processing conditions on the effective strain, the rotation angle and the effective stress induced within the extruded billet. The numerical results provide valuable insights into the shear plastic deformation behavior of CuZn37 brass alloy during the CCA extrusion process. Introduction In general, rolling, extrusion and forging processes subject the working material to very high strains. The resulting plastic deformation causes a significant change in the physical and mechanical properties of the material. Accordingly, there are significant benefits to be gained from deforming metallic alloys under very high levels of plastic strain. The equal channel angular (ECA) extrusion process (also known as equal channel angular pressing (ECAP)) was first developed by Segal et al. [1-2] as a means of inducing large plastic strains within metallic workpieces without causing a significant change in their outer dimensions. More recently, Liu et al. [3] presented a novel changing channel angular (CCA) extrusion method designed to reduce the tensile stress within the workpiece and to increase the hydrostatic pressure during the extrusion process. Kim [4] used commercial DEFORM TM 2D software to perform a finite element analysis (FEA) investigation into the formation of corner gaps between the die and the workpiece during the plane strain ECAP process. In analyzing the multiple-pass ECAP process, Figueiredo et al. [5] neglected the strain path effect and predicted the material deformation behavior in each pass using a single stress-effective strain curve. Meanwhile, the present authors [6] applied a FE method to investigate the plastic deformation behavior of Ti-6Al-4V titanium alloy during one-and two-turn ECA extrusion. The current study uses DEFORM TM 2D FE code to investigate the plastic deformation behavior of CuZn37 brass alloy during one-and two-turn CCA extrusion processing, in which high strains are induced within the billet by passing it through a series of channels of unequal cross-sections arranged such that they form specified internal angles. The simulations focus particularly on the effects of the CCA processing conditions on the distributions of the effective strain, rotation angle and effective stress, respectively, within the extruded workpiece

Experimental Investigation into Suitable Process Conditions for Plastic Injection Molding of Thin-Sheet Parts

This study performs an experimental investigation into the effects of the process parameters on the surface quality of injection molded thin-sheet thermoplastic components. The investigations focus specifically on the shape, number and position of the mold gates, the injection pressure and the injection rate. It can be seen that the gravity force entering point improved filling of the cavity for the same forming time and injection pressure. Moreover, it shows the same injection pressure and packing time, the taper-shape gate yields a better surface appearance than the sheet-shape gate. The experimental results provide a useful source of reference in suitable the process conditions for the injection molding of thin-sheet plastic components

Stimulating the Influence of Teaching Effectiveness and Students’ Learning Motivation by Using the Hierarchical Linear Model

In the context of school learning and teaching, teachers are leaders who stimulate students’ learning outcomes through leadership styles. The teacher efficacy of this study is discussed by using multiple teaching and class management strategies. Because the situation of each school is different, the contingency theory is used to design the research structure. This study changed the original leadership style to the new leadership style; effectiveness to teacher effectiveness; and context to school context, and set them as moderators. Since the unit of analysis is teachers, it is difficult to find factors such as differences in regression coefficients in the school context. Therefore, the HLM hierarchical linear analysis is used, and the school context is set as the second level, and then statistical analysis is performed. Teachers’ leadership styles have significant differences in multiple teaching strategies for teacher effectiveness. Moral leadership and charismatic leadership have a moderating effect on the multiple teaching strategies of teacher effectiveness. The multiple teaching strategies of teacher effectiveness have a significant effect in middle school situations with lower moral leadership. On the other hand, charismatic leadership is more pronounced in middle school situations than in high school situations. Teachers’ leadership styles have a significant impact on classroom management of teacher effectiveness. Under the situational control of schools, moral leadership, charismatic leadership, and supportive leadership have moderating effects on classroom management of teacher effectiveness. When the classroom management of teacher effectiveness is in the middle school situation, low moral leadership is more significant; in the high school situation, charismatic leadership will reduce the effectiveness of the class management; in the moderate or high situation, the higher the support of the leader, the greater the effect of class management