• Transactions of Materials Processing
• /
• v.8 no.3
• /
• pp.262-268
• /
• 1999

This paper reviews the rules for optimizing die design and the process variables such as die shoulder radius and punch to die clearance, which are important factors in drawing the sheet metal without failures during deep drawing. To find the optimum conditions for improving deep drawability, a series of the experiments are performed, and the wall thinning and thickening variations are investigated in each process of deep drawing for a complex cylindrical shell. From the results of this proposed experiment, the optimum values of process variables are examined and discussed, and the usefulness of the present suggestion is shown.

• Transactions of Materials Processing
• /
• v.23 no.1
• /
• pp.23-28
• /
• 2014

The aspect ratio of a hole is defined as the ratio of the thickness to the diameter of the sheet metal. Most holes in the sheet metal industry are made by piercing. However, for thick sheets, which have an aspect ratio greater than 2, a machining process like drilling instead of piercing is usually used to make holes. In the current study, piercing, which is a shearing process, is evaluated to punch a hole with a high aspect ratio by using a newly designed die set-up. The piercing die was manufactured to prevent the punch from buckling and also to improve the alignment between the die components. An aluminum alloy sheet was selected for the experiments. The influence of several process parameters such as sheet thickness, clearance and stripping force were investigated. Experimentally, a hole with an aspect ratio of 5 was pierced. The resulting hole had a clean surface and the dimensional accuracy of pierced hole was considerably improved with decreasing clearance between punch and die. It is also shown that the larger penetration depth of the effective sheared surface can be achieved for high aspect ratio piercing relative to conventional piercing with a low aspect ratio.

• Journal of the Korean Society for Precision Engineering
• /
• v.17 no.9
• /
• pp.62-69
• /
• 2000

Uneven clearances in the left and right sides of a press die cause deformation of the punch in precision shearing process. This deformation results from the compression stress and bending moment from shearing force in vertical direction and from the side force in horizontal direction acting to the punch, In this study the behavior of punch deformation is investigated in order to clarify the deformation state of the punch by using strain gauge deformation to shearing force side force bending moment radius of curvature and shear plane of the punch. Also we presented the calculation method of deformation size for the punch.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2002.02a
• /
• pp.260-265
• /
• 2002

In micro hole punching process, it is very difficult to align punch with die hole. Misalignment can cause a falling-on in hole quality and breakage of punch and die. Micro punching using soft die plate without a die hole has a big advantage because it is not necessary to align punch with die hole and to consider die clearance. Soft die plates are made by polymers or hard rubbers which are softer than metals. In this study, several micro punching experiments are conducted. Micro punching test with some materials shows that micro hole punching is feasible with some soft die plates. Through the section shape obtained by mounting and polishing, the punched hole quality is measured and the shapes of burr and dome we studied.

• Design & Manufacturing
• /
• v.15 no.4
• /
• pp.51-56
• /
• 2021

Piercing is the process of shearing a circular hole in sheet metal, whose high shear force makes it difficult to secure the durability of tools. In addition, uneven clearance between tools due to poor alignment of the piercing punch causes accelerated die wear and breakage of the tool. This study reviewed the feasibility of in-situ determining alignment failure during the piercing process by analyzing the signal deviation of a bolt-type piezo sensor installed inside the tool whose alignment level was controlled. Finite element analysis was performed to select the optimal sensor location on the piercing tool for sensitive detection of process signals. A well-aligned piercing process results in uniform deformation in the circumferential direction, and shearing is completed at a stroke similar to the sheet thickness. Afterward, a sharp decrease in shear load is observed. The misaligned piecing punch leads to a gradual decrease in the load after the maximum shear load. This gradual decrease is due to the progressive shear deformation that proceeds in the circumferential direction after the initial crack occurs at the narrow clearance site. Therefore, analyzing the stroke at which the maximum shear load occurs and the load reduction rate after that could detect the misalignment of the piercing punch in real-time.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2001.10a
• /
• pp.280-285
• /
• 2001

A good drawability of material itself is required. To improve the formability in deep drawing process. Besides that bending resistance should be reduced by increasing die round appropriately, drawing load should be minimized by improving the lubricant condition between die and material, and breaking load should be increased by selecting a pertinent punch round and by augmenting the friction resistance in Punch. In this study, a multi-stage deep drawing process is analyzed using ABAQUS, the effects of formability factors. Such as die shoulder radius, punch-die clearance and friction coefficient are investigated.

• Journal of the Semiconductor & Display Technology
• /
• v.10 no.3
• /
• pp.61-65
• /
• 2011

The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile. In this study, three dimensional finite element analysis is carried out to design a lead frame blanking die using LS-Dyna3D package. After design of the blanking die, an experiment is also carried out to investigate the characteristics of blanking for nickel alloy Alloy42, a kind of IC lead frame material. In this paper, it has been researched the investigation to examine the influence of process parameters such as clearance and air cylinder pressure on the accuracy of sheared plane. Through the experiment results, it is shown that the quality of sheared plane is less affected by clearance and air cylinder pressure.

• Design & Manufacturing
• /
• v.10 no.3
• /
• pp.34-38
• /
• 2016

Roll forming is a continuous production process that is mass-produced. The roll forming process is produced in various forms. The special feature of roll forming is a continuous production. Therefore, the process of cutting the material is essential. The troubles in a shearing process affects the low productivity. Accordingly, it is important to reduce the factors that inhibit the material flow. And it is difficult to apply the common shear angle. Because it is not a simple forms, such as a progressive die. This study shows how to select the angle of a shear punch and the shape of a cutting punch in the product with a specific shape. Conclusively through three different model, it is advantageous to apply the different shear angle and clearance along the forms.

• Design & Manufacturing
• /
• v.17 no.3
• /
• pp.15-20
• /
• 2023

In the fine blanking process, which is a press operation known for producing parts with narrow clearances and high precision through the application of high pressure, die roll often occurs during the shearing process when the punch penetrates the material. This die roll phenomenon can significantly reduce the functional surface of the parts, leading to decreased product performance, strength, and fatigue life. In this research, we conducted an in-depth analysis of the factors influencing die roll in the curvature area of the fine blanking process and identified its root causes. Subsequently, we designed and experimentally verified a die roll reduction process specifically tailored for the door latch manufacturing process. Our findings indicate that die roll tends to increase as the curvature radius decreases, primarily due to the heightened bending moment resulting from reduced shape width-length. Additionally, die roll is triggered by the absorption of initial punch energy by scrap material during the early shearing phase, resulting in lower speed compared to the product area. To mitigate the occurrence of die roll, we strategically selected the Shaving process and carefully determined the shaving direction and clearance area length. Our experiments demonstrated a promising trend of up to 75% reduction in die roll when applying the Shaving process in the opposite direction of pre-cutting, with the minimum die roll observed at a clearance area length of 0.2 mm. Furthermore, we successfully implemented this approach in the production of door latch products, confirming a significant reduction in die roll. This research contributes valuable insights and practical solutions for addressing die roll issues in fine blanking processes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.9
• /
• pp.517-524
• /
• 2019

The overdrive hub clutch is attached to a 6-speed automatic transmission to reduce fuel consumption by using the additional power of the engine. This paper proposes a means to minimize the load and roll-over ratio on the punch during the piercing process for the overdrive hub clutch product. Die clearance, shear angle, and friction coefficient, which can affect the load and roll-over ratio of the punch during processing, were set as the design variables. Sensitivity analysis was also conducted to determine the influence of each design variable on the punch load and roll-over ratio. As a result, shear angle, friction coefficient and die clearance were found to be sensitive to load and roll-over ratio. The punch load and roll-over ratio were set as the objective function and the equation of each design variable and objective function was derives using the Response Surface Method. Finally, the optimal value of the design variables was derived using the Response Surface Method. Application of this model to finite element analysis resulted in 22.14% improvement in the roll-over ratio of the punch load and material.