Computer Aided Process Planning for 3D Printing

Park, Hong-Seok,Tran, Ngoc-Hien The Korean Society of Manufacturing Technology Eng 2015 한국생산제조학회지 Vol.24 No.2

Computer aided process planning (CAPP) keeps an important role between the design and manufacturing engineering processes. A CAPP system is a digital link between a computer aided design (CAD) model and manufacturing instructions. CAPP have been researched and applied in manufacturing filed, however, one manufacturing area where CAPP has not been extensively researched is rapid prototyping (RP). RP is a technique for creating directly a three dimensional CAD data into a physical prototype. RP enables to build physical models automatically and to use to reduce the time for the product development cycle as well as to improve the final quality of the designed product. Three-dimensional (3D) printing is one kind of RP that creates three-dimensional objects from CAD models. The paper presents a computer aided process planning system for printing medical products. 3D printing has been used to solve complex medical problems such as surgical instruments, bioengineered products, medical implants, and surgical guides.

Finite element analysis for dynamic behavior of a machine tool structure fed in open loop control

최진우,이태홍,Choi, Jin-Woo,Lee, Tae-Hong The Korean Society of Manufacturing Technology Eng 2010 한국공작기계학회지 Vol.19 No.5

In this study, a fmite element model was developed for analysis of feeding a structure in open loop control The finite element analysis (FEA) can simulate dynamic behavior of the structure of a machine tool rapidly traveling with a screw feeding driving system. The feeding mechanism was implemented with screw element of the FEA tool used in this study. The procedure was developed for the dynamic transient FEA. First, motion parameters such as jerk and velocity were introduced for the structure to be fed in open loop control When its traveling distance was determined, set-points for the distance were generated based on the motion parameters. The set-points were applied to the FE model constructed for the traveling structure. The FEA was executed and evaluated. In this study, the FEA procedure was applied to the column of a machine tool and the dynamic behavior of the column was evaluated. The FEA helps in evaluation of the motion characteristics of a structure. The convergence time of the structure vibration posterior to feeding termination can be estimated and the stiffness of the flexible structure is also evaluated against jerk, and acceleration. It provides the feeding force which is helpful in selection of the feeding motor.

Simple Analysis of the Properties of Condenser Lens 1 in SEM

임선종,Lim, Sun-Jong The Korean Society of Manufacturing Technology Eng 2010 한국공작기계학회지 Vol.19 No.5

It is quite complex to draw the geometry of electron trajectories in electron optics because such trajectories have various aberrations that cannot be easily calculated. However, if we need to know roughly the geometry, the focal length and the principal planes in order to understand the properties of column, a simple numerical solution can be a useful method. We are developing the electron beam machining system based on SEM. In this paper, we show rough geometry, focal length and principal planes by a numerical solution for electron lens I in our column. These results will be utilized in developing a simulation program for electron optics.

Reliability-Based Topology Optimization Based on Bidirectional Evolutionary Structural Optimization

유진식,김상락,박재용,한석영,Yu, Jin-Shik,Kim, Sang-Rak,Park, Jae-Yong,Han, Seog-Young The Korean Society of Manufacturing Technology Eng 2010 한국공작기계학회지 Vol.19 No.4

This paper presents a reliability-based topology optimization (RBTO) based on bidirectional evolutionary structural optimization (BESO). In design of a structure, uncertain conditions such as material property, operational load and dimensional variation should be considered. Deterministic topology optimization (DTO) is performed without considering the uncertainties related to the design variables. However, the RBTO can consider the uncertainty variables because it can deal with the probabilistic constraints. The reliability index approach (RIA) and the performance measure approach (PMA) are adopted to evaluate the probabilistic constraints in this study. In order to apply the BESO to the RBTO, sensitivity number for each element is defined as the change in the reliability index of the structure due to removal of each element. Smoothing scheme is also used to eliminate checkerboard patterns in topology optimization. The limit state indicates the margin of safety between the resistance (constraints) and the load of structures. The limit State function expresses to evaluate reliability index from finite element analysis. Numerical examples are presented to compare each optimal topology obtained from RBTO and DTO each other. It is verified that the RBTO based on BESO can be effectively performed from the results.

Crack Propagation at Boundary Face of Composite Compact Tension Specimen

Cho, Jae-Ung,Han, Moon-Sik The Korean Society of Manufacturing Technology Eng 2013 한국생산제조학회지 Vol.22 No.2

In this study, fatigue crack propagation in composite material under fatigue is investigated by simulation result. When another material on the specimen exists vertically to the crack line, the phenomena that crack may go straight or propagate along the boundary face according to the elastic modulus ratio of another material to matrix are investigated with compact tension specimen by compliance method. Crack propagation direction is evaluated by compliance method. By arranging this study result systematically about the crack propagation behavior due to the stiffness of inhomogeneous material, high-tech material (automobile, aircraft and steel industry) can be improved. The estimation of safety design and life (construction & nuclear power station, etc.) will be of great value industrially.

The Development of an Automatic Molten Metal Supplier for an Aluminum Thermal Furnace

이준호,Lee, Jun-Ho The Korean Society of Manufacturing Technology Eng 2009 한국공작기계학회지 Vol.18 No.5

The objective of this development project is to localize an automatic molten metal supplier that has been distributed by WESTOMAT, Germany, throughout the world. To achieve this purpose, an energy-saving pressurized dosing furnace and molten metal differential pressure control system that Is able to automatically supply a determined quantity of aluminum molten metal were developed. The localized equipment was installed in a site. Also, the results of the test operation of this equipment can be summarized as follows: It was able to improve the productivity because there were small decreases in supplying speeds and small losses in wastes compared to the existing mechanical molten metal supplier. Also, it was able to minimize the cost in maintenances due to the direct application of high temperature molten metals to molds. In addition, there were small energy losses due to the use of high thermal insulators compared to the existing reverberating furnace and able to prolong the life-time of furnaces and produce good quality nonferrous metals because it represented small carbon refractories and alumina in applied molten metals. Furthermore, it demonstrated no particular differences by objectively comparing it with the product by WESTOMAT.

Development of a New Navigation Technology for Mobile Robot Based on Sonar Sensors

노연판쿠에트,한성현,Nguyen, Van-Quyet,Han, Sung-Hyun The Korean Society of Manufacturing Technology Eng 2009 한국공작기계학회지 Vol.18 No.6

This paper presents the theoretical development of a complete navigation problem of a non-holonomic mobile robot by using sonar sensors. To solve this problem, a new method to compute a fuzzy perception of the environment is presented, dealing with the uncertainties and imprecision from the sensory system and taking into account nonholonomic constraints of the robot. Fuzzy perception, fuzzy controller are applied, both in the design of each reactive behavior and solving the problem of behavior combination, to implement a fuzzy behavior-based control architecture. Different experiments in populated environments have proved to be very successful. Our method is able to guide the mobile robot named KUM-Robo safety and efficiently during long experimental time.

Effect of Austempering Treatment on Dynamic Characteristics of Brake Drums

임경빈,Yim, K.B. The Korean Society of Manufacturing Technology Eng 2010 한국공작기계학회지 Vol.19 No.1

The effect of austempering treatment on the dynamic properties of a brake drum was investigated to primarily evaluate the potential damping advantage of an AGI (austempered gray iron) drum over a PGI (pearlitic gray iron) drum. This investigation provides valuable information for brake noise reduction since the brake drum is most often the outstanding component that generates the noise of the brake assembly. Test results show that the AGI drum provided slightly larger damping values than the PGI drum for the first few major resonances observed. A finite element model of a drum was also developed to aid in studying its dynamic behavior. A good correlation was obtained between the analytical results and the actual measurement data.

A Study on the Rotating Ring Using Air Bearing in Yarn Manufacturing Process

장승호,Jang, Seung-Ho The Korean Society of Manufacturing Technology Eng 2010 한국공작기계학회지 Vol.19 No.5

The increase of the spindle speed to enhance the productivity in ring spinning processes has been limited by yarn tension and heat generation of the traveller/ring. The main causes of yarn tension are 1) the force added directly to the yarn by the rotation of the spindle and 2) the centrifugal force exerted by the yarn balloon generated by traveller rotation. The dominant causes of heat generation are 1) the friction between the ring and traveller and 2) the friction between the traveller and yarn. These factors cause yarn end-breaks and heat damage. In the case of the staple yarn manufacturing process for PET (polyester) and nylon (a heat plasticity material), the rotational speed of the ring spinning system has deteriorated to 10,000rpm. The objective of this study was to develop a rotating ring which has dynamic stability, high productivity and a simple structure to overcome the limitations of the conventional fixed ring/traveller system. The results of this study revealed that the spinning tension could be reduced by 67.8% using the newly developed rotating ring.

Sensitivity Correlations of Electrical Vehicle

이정익,Lee, Jeong-Ick The Korean Society of Manufacturing Technology Eng 2009 한국공작기계학회지 Vol.18 No.4

Generally, finite element models used in structural analysis have some uncertainties of the geometric dimensions, applied loads and boundary conditions, as well as in material properties due to the manufacturability of aluminum intensive body. Therefore, it is very important to refine or update a finite element model by correlating it with dynamic and static tests. The structural optimization problems of automotive body are considered for mechanical structures with initial stiffness due to preloading and in operation condition or manufacturing. As the mean compliance and deflection under preloading are chosen as the objective function and constraints, their sensitivities must be derived. The optimization problem is iteratively solved by a sequential convex approximation method in the commercial software. The design variables are corrected by the strain energy scale factor in the element levels. This paper presents an updated method based on the sensitivities of structural responses and the residual error vectors between experimental and simulation models.