Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 215-224).

A real-time dynamic feedback control system is developed. An improved PID algorithm, called the integral separated piecewise PID scheme, is used in the control system. This algorithm is able to limit the contribution of the integral component in the PID calculation to avoid integral windup. In addition, it could use different PID parameters to adapt to different segments within one punch motion cycle. Hence, the error of the punch motion, either resulting from the machine assembly or from the machine dynamics, can be compensated by tuning the velocity of the servomotor. This is a unique feature of the new press that ensures its accuracy. / Based on the novel structure, the detailed design is then carried out, which includes the mechanical design, kinematics and inverse kinematics analysis, static force analysis, parametric design and the other related designs. A calibration method based on the experiment and computer simulation is proposed for the new press, which is also useful for the parallel mechanisms. Cooperated with Guangdong Metal Forming Machine Works Co. Ltd., a 250 KN prototype has been built and tested. / In order to ensure the desirable performance, dynamic control is necessary. The thesis uses two dynamic modeling methods to study the dynamics of the press. One is the kineto-static method. It is also called D'Alembert principle which rearranges Newton's second law and transfers a dynamic problem to an equivalent static problem by adding the inertial forces and inertial torques onto the system. The model can then be analyzed easily and exactly as a static system subjected to the inertial forces and torques and the external forces. The other method is the Lagrangian method which derives the dynamic model from the energy perspective. Based on the model, the dynamics of the press is studied by means of computer simulation and is validated experimentally. / In this thesis, a controllable hybrid mechanical metal forming press is developed, which is driven by a CSM with a flywheel and a servomotor. From a mechanism point of view, it is a closed-loop 2-DOF parallel planar five-bar mechanism with four resolute joints and one prismatic joint. Thanks to the usage of the servomotor, the punch motion of the new press can be controlled by tuning the velocity of the servomotor. Accordingly, desired punch motions for different stamping processes can be obtained. In other words, the new press is flexible and controllable like the servo mechanical press and the hydraulic press. Moreover, the CSM with flywheel provides the main power during the stamping operation, and hence, it is energy efficient. In addition, it is not expensive to build, as it uses only a small servomotor. / Metal forming is one of the oldest production processes and yet, is still one of the most commonly used processes today. Everyday, millions of parts are produced by metal forming ranging from battery caps to automobile body panels. Therefore, even a small improvement may add to significant corporative gain. / The thesis also describes the trajectory planning method for the press, which is based on the combination of the inverse kinematics and cubic spline interpolation. The trajectory is optimized under multiple constraints on velocity, acceleration and jerk of the servomotor. It guarantees the new press is controllable and energy efficient. / Two typical stamping processes, drawing and forging, are taken as examples for the operations of the new press. The results of the simulation and the experiment match well. Based on the simulation and experiments, it is found that the CSM provides the main power for the metal forming operations, while the servomotor is mainly responsible for overcoming the inertia forces to realize the desired punch motion. The experiments show that the new press is energy efficient, fast, controllable and inexpensive to build. It combines the advantages of both mechanical press and hydraulic press and has a good performance. It is expected the new press will have a great potential for the metal forming industry. (Abstract shortened by UMI.) / He, Kai. / "February 2008." / Adviser: Ruxu Du. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1902. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 147-149). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Thesis (Ph.D.)--Virginia Commonwealth University, 2009. / Prepared for: Dept. of Mechanical Engineering. Title from title-page of electronic thesis. Bibliography: leaves 162-172.

Ng Yiu Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 110-114). / Abstracts in English and Chinese. / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Diagnosis concept based on thermal energy distribution --- p.6 / Chapter 1.1.1 --- A cup drawing example --- p.8 / Chapter 1.2 --- Need for 3D infrared thermal distribution measurement --- p.10 / Chapter 1.3 --- Outline of the Thesis --- p.11 / Chapter 2. --- Approach --- p.15 / Chapter 2.1 --- Similarity and extreme temperature analysis --- p.15 / Chapter 2.2 --- Thermodynamics for FEA in sheet metal stamping --- p.17 / Chapter 2.3 --- Acquisition of 3D thermal distribution --- p.20 / Chapter 3. --- Implementation of the Diagnosis System --- p.23 / Chapter 3.1 --- Thermograph acquisition --- p.23 / Chapter 3.2 --- Diagnosis system setup --- p.24 / Chapter 3.3 --- Perspective camera model --- p.25 / Chapter 3.4 --- System calibration --- p.27 / Chapter 3.4.1 --- LEDs calibration board --- p.27 / Chapter 3.4.2 --- Net-and-board calibration box --- p.29 / Chapter 3.5 --- Reconstruction algorithm --- p.33 / Chapter 3.6 --- Summary --- p.37 / Chapter 4. --- Consistency from Different Viewpoints --- p.38 / Chapter 4.1 --- Summary --- p.42 / Chapter 5. --- Visual Reconstruction of Objects --- p.44 / Chapter 5.1 --- Visual camera calibration --- p.45 / Chapter 5.2 --- Results --- p.49 / Chapter 5.2.1 --- "Cartoon model ""SiuSun""" --- p.49 / Chapter 5.2.2 --- Stamping disc --- p.51 / Chapter 5.3 --- Summary --- p.53 / Chapter 6. --- Thermal Distribution Reconstruction of Stamping Workpieces --- p.54 / Chapter 6.1 --- Infrared camera calibration --- p.54 / Chapter 6.2 --- Results --- p.57 / Chapter 6.2.1 --- Air conditioner cap --- p.57 / Chapter 6.2.2 --- Deep drawing cup --- p.59 / Chapter 6.2.3 --- Stamping cylinder from KS Factory --- p.61 / Chapter 6.3 --- Summary --- p.65 / Chapter 7. --- Infrared Camera on a Robotic Arm --- p.66 / Chapter 7.1 --- Robotic arm system setup --- p.67 / Chapter 7.2 --- System calibration --- p.68 / Chapter 7.3 --- Results --- p.77 / Chapter 7.3.1 --- Image sequence from horizontal viewpoints --- p.77 / Chapter 7.3.2 --- Image sequence from inclined viewpoints --- p.80 / Chapter 7.3.3 --- Image sequence from arbitrary viewpoints --- p.83 / Chapter 7.4 --- Comparison of the three different viewpoints --- p.85 / Chapter 7.5 --- Summary --- p.87 / Chapter 8. --- Compensation of Temperature Fade-out Problem --- p.88 / Chapter 8.1 --- Causes of temperature fade-out --- p.88 / Chapter 8.2 --- Solutions --- p.90 / Chapter 8.3 --- Summary --- p.91 / Chapter 9. --- Other Applications --- p.92 / Chapter 9.1 --- Automotive industry --- p.92 / Chapter 9.1.1 --- Background --- p.93 / Chapter 9.1.2 --- Experiment and result --- p.94 / Chapter 9.2 --- General heat transfer analysis --- p.97 / Chapter 9.3 --- Summary --- p.98 / Chapter 10. --- Conclusions --- p.99 / Chapter 10.1 --- Summary --- p.99 / Chapter 10.2 --- Future work --- p.104 / Chapter A. --- Transformation Matrices of the System --- p.106 / Bibliography --- p.110

No description available.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 187-192).

"March 2003." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (p. 183-193). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xxv, 222 p.; also includes graphics (some color). Includes bibliographical references (p. 185-191).

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2016. / The purpose of this study is the optimisation of the stamping analysis process in order to investigate the possible reasons for the part failure. (Altan & Vasquez, 2000) have conducted similar research to optimise a forming process. However, they focussed on dies for a forging process and in this study, we are looking at cold forming and this study is also different in that we are trying to reduce the number of stages while maintaining the formability. Formability is based on the dimensional conformance of the final part with additional criteria being the thinning, appearance of wrinkling, dynamic effects leading to the localisation of strain, cracking and residual stress. A numerical modelling procedure that is close enough to the real process is used to investigate the effects of changes in the frictional contact that would correspond to lubrication and also the effect of adding draw beads to the forming tools to change the frictional contact. We also investigated the effect of using a different material in terms of meeting the design requirements. Experimental results for comparison are available for certain of the stamping processes investigated that were tested in pre-production. The finite element simulation is used to account for all residual thinning, stress and strain of the multi-stage forming process to ensure optimum thickness changes of the sheet at each stage. The variations of material and manufacturing parameters are established to accurately predict the behaviour of this specific forming process. The material model required to meet physical experiments is deduced from the results of standard tensile tests and fitted to the Hill’s 48 Law for Work Hardening. The commercial packages Ls-Dyna with Dynaform and Pam-Stamp software are used for the simulation to produce 2 results for comparison.

After the review of the basic theory of the inverse method, a new modified arc-length search method is proposed to find better initial solution. The methods to deal with the vertical walls are also discussed and presented. Then, a generalized multi-step inverse FEM method is proposed. It solves two key obstacles: the first one is to determine the initial solution of the intermediate three-dimensional configurations and the other is to control the movement of nodes so they could only slide on constraint surfaces during the search by Newton-Raphson iteration. The computer implementation of the generalized multi-step inverse FEM is also presented. By comparing to the simulation results using a commercial software system, the effectiveness of the new method is validated. / Currently, there are a number of commercial FEM software systems available in the market. These software systems are based on an incremental FEM process that models the sheet metal stamping process in small incremental steps. Even though the incremental FEM is accurate, it is not suitable for the initial conceptual design for its needing of detailed design parameters and enormous calculation times. As a result, another type of FEM, called the inverse FEM method or one-step FEM method, has been proposed. While it is less accurate than that of the incremental method, this method requires much less computation and hence, has a great potential. However, it also faces a number of unsolved problems, which limits its application. This motivates the presented research. / From a physical point of view, the formability and the quality of a product are influenced by several factors. The design of the product in the initial stage and the motion of the press during the production stage are two of these crucial factors. This thesis focuses on the numerical simulation for these two factors using FEM. / Other than the product design, the punch motion (including punch speed and punch trajectory) of the stamping press also has significant effect on the formability and the quality of the product. In fact, this is one of the major reasons why hydraulic presses and/or servo presses are used for parts which demand high quality. In order to reveal the quantitative correlation between the punch motion and the part quality, the Cowper-Symonds strain rate constitutive model and the implicit dynamic incremental FEM are combined to conduct the research. The effects of the punch motion on the part quality, especially the plastic strain distribution and the potential springback, have been investigated for the deep drawing and the bending processes respectively. A qualitative relationship between the punch motion and the part quality is also derived. / The reaction force of the punch motion causes the dynamic deformation of the press during the stamping, which in turn influences the part quality as well. This dynamic information, in the form of the strain signal, is an important basis for the on-line monitoring of the part quality. By using the actual force as the input to the press, the incremental FEM is needed to predict the strain of the press. The result is validated by means of experiments and can be used to assist the on-line monitoring. / The sheet metal stamping process plays an important role in modern industry. With the ever-increasing demand for shape complexity, product quality and new materials, the traditional trial and error method for setting up a sheet metal stamping process is no longer efficient. As a result, the Finite Element Modeling (FEM) method has now been widely used. / Huang Ying. / "March 2006." / Adviser: Ruxu Du. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6694. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 141-160). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.