• Transactions of Materials Processing
• /
• v.23 no.8
• /
• pp.501-506
• /
• 2014

Progressive shearing with blanking dies is commonly employed to produce large quantities of tiny sheet metal electronic parts. Sheet metal pins, which are narrow and long, that are sheared with a progressive die set are often twisted. The twist in the sheet metal pins, which usually occurs in the final shearing operation, generally decreases with increasing blank holding force. The blank holding forces in all shearing operations are not the same because of different shearing positions and areas. In the current study, the optimal layout of the springs in a progressive die set to minimize the twist of the sheet metal pin is proposed. In order to find the holding force acting on the tiny narrow blanks produced with the proposed springs during the shearing process, the equivalent area method is used in the structural analysis. The shearing of the sheet-metal pin was simulated to compute the twist angle associated with the blank holding force. The constraint condition satisfying the pre-set blank holding force from the previous shearing operations was imposed. A design of experiments (DOE) was numerically implemented by analyzing the progressive die structure and by simulating the shearing process. From the meta-model created from the experimental results and by using a quadratic response surface method (PQRSM), the optimal layout of the springs was determined. The twist of sheet metal pin associated with the optimal layout of the springs found in the current study was compared with that of an existing progressive die to obtain a minimal amount of twist.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.1
• /
• pp.79-92
• /
• 2002

This paper describes a research work of developing computer-aided design of a product with bending and piercing for progressive working. An approach to the system for progressive working is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, strip layout and die layout modules. The system is designed by considering several factors, such as bending sequences by fuzzy set theory, complexities of blank geometry, punch profiles, and the availability of a press equipment. Strip layout drawing generated in the strip layout module is presented in 3-D graphic farms, including bending sequences and piercing processes with punch profiles divided into for external area. The die layout module carries out die design for each process obtained from the results of the strip layout. Results obtained using the modules enable the manufacturer for progressive working of electric products to be more efficient in this field.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.45 no.4
• /
• pp.157-166
• /
• 2022

In the case of a die-casting process, defects that are difficult to confirm by visual inspection, such as shrinkage bubbles, may occur due to an error in maintaining a vacuum state. Since these casting defects are discovered during post-processing operations such as heat treatment or finishing work, they cannot be taken in advance at the casting time, which can cause a large number of defects. In this study, we propose an approach that can predict the occurrence of casting defects by defect type using machine learning technology based on casting parameter data collected from equipment in the die casting process in real time. Die-casting parameter data can basically be collected through the casting equipment controller. In order to perform classification analysis for predicting defects by defect type, labeling of casting parameters must be performed. In this study, first, the defective data set is separated by performing the primary clustering based on the total defect rate obtained during the post-processing. Second, the secondary cluster analysis is performed using the defect rate by type for the separated defect data set, and the labeling task is performed by defect type using the cluster analysis result. Finally, a classification learning model is created by collecting the entire labeled data set, and a real-time monitoring system for defect prediction using LabView and Python was implemented. When a defect is predicted, notification is performed so that the operator can cope with it, such as displaying on the monitoring screen and alarm notification.

• Transactions of Materials Processing
• /
• v.19 no.1
• /
• pp.17-24
• /
• 2010

A stretch forming method has been widely used in sheet metal forming process. Especially, this process has been adopted in aircraft and high-speed train industries for skin structure forming having a variety of curvature. Until now, solid dies, which are designed with respect to the specific shapes and manufactured as a single piece, have been usually applied to stretch forming process. Therefore, a great number of solid dies has to be developed according to the shapes of the curved skin structure. Accordingly, a flexible die is proposed in this study. It replaces the conventional solid dies with a set of height adjustable punch array. A usefulness of the flexible die is verified through a formability comparison with the solid die using finite element method considering an elastic recovery and the stretch forming apparatus with the flexible die is developed.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1587-1590
• /
• 2005

A rigid-plastic finite element analysis for the die forging process of a socket ball joint, which is used in the transportation system, was carried out. And also with the results, the elastic stress analysis for the forging die was performed in order to get basic data for the die life prediction. The die fatigue life prediction was simulated using Goodman's and Gerber's equation. The prediction technique for the fatigue life of a forged product, the socket ball joint, using DEFORM-3D is presented and the results are commented upon. Archard's wear model was used for the wear simulation and then the wear simulation and then the wear quantity was quantity was evaluated using volume. In order to prove the wear simulation results to be reliable, wear quantity of the real forging die set in used a forging factory was measured using a 3-dimensional measurement apparatus. The simulation results were relatively in good agreement with the experimental measurements.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.214-218
• /
• 1995

Much labor, an exceedingly long lead time, and the skills of experienced engineers are required for press tool design. To reduce such problems, several CAD systems for blanking or piercing have been developed. This paper describes a computer-aided design for blanking or piercing of irregularly shaped sheet metal products. An approach to the system is based on knowledge base rules. The process planning & die design system is designed by considering several factors, such as complexity of blank geometry, punch profile, and availability of press equipment and standard parts. Therefore, after checking a production feasibility for irregular shaped sheet metal products, this system which is implemented strip layout module can carry out a process planning and generate the strip layout in graphic forms. Also this system implemented die layout module can carry out a die design for each process which is obtained form the result of an automated process planning and generate parts and assembly drawing of a die set.

• Proceedings of the KSME Conference
• /
• 2001.06c
• /
• pp.627-632
• /
• 2001

Nimonic 80A superalloy with high-temperature strength and high corrosion-resistance is used in jet engine for aircraft, gas turbine for power plant and marine diesel engine, etc. To develop the manufacturing process of exhaust valve for large diesel engine using Nimonic 80A, various mechanical tests, such as hot compression, microstructure and hardness test have been performed. This results effectively used to set the reasonable forging conditions while hot forging of Nimonic 80A superalloy. Open die and closed die forging experiments are carried out from ESR ingot and finally get a good shaped exhaust valve product.

• Transactions of Materials Processing
• /
• v.7 no.4
• /
• pp.347-353
• /
• 1998

A new approach of elastic finite element to die stress analysis in forging is presented in this paper. The die set analysis problem is formulated by considering contact problems under both mechanical and thermal loads. In the approach, amount of shrink fit is controlled by thermal load i.e., temperature difference between die insert and shrink fits. The loading conditions are extracted automatically from a forging simulator. The predicted solution is compared with analytical one and it has been shown that the predicted results are in excellent agreement with the analytical ones. An application example is given, which was found in a cold forging company.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.7 no.4
• /
• pp.14-20
• /
• 1998

This paper describes a computer-aided die design system of progressive die for making CPT grid. An approach to the development of the automatic design system is based on knowledge-based rules. The developed system is designed by considering several factors, such as grid geometry and punch profile. Grid, a key component of electronic gun, is formed through a sequence of many operations, among which the pilot piercing, beading, notching, bending, swaging and slotting etc. Using the developed system, design parameters are determined and output is generated in graphic forms. Therefore the developed system provides part drawing and the assembly drawing of die set.

• Transactions of Materials Processing
• /
• v.14 no.2 s.74
• /
• pp.147-152
• /
• 2005

The objective of this study is to develop an optimal drawing die for the clad wire drawing process. Cu-clad wire, which has the advantages of the high strength of a steel core and the electro-conductivity, corrosion resistance of a copper layer, is widely being used in the field of the telecommunications, electric-electronic and military technology industries. It is important to obtain uniformly coated rate when producing clad wires. Drawing process of clad wire will be influenced on damage and coated rate of core and sleeve for process variables such as semi-die angle and reduction in area. Therefore, in this study, the finite-element result obtained in this study was analyzed to the effect of the various forming parameters, which included the semi-die angle and reduction in area. The coated rate will be predicted with observation of copper coated rate variation according to total reduction in area and the optimal pass schedule will be set up through proper reduction in area and semi-die angle variation.