• Transactions of Materials Processing
• /
• v.27 no.5
• /
• pp.276-280
• /
• 2018

This paper has developed a forging process for conical shells for making aluminum cylindrical large shells. An incremental forging process was applied to reduce forging loads and die cost. The preform is designed based on the crosssectional area of the final forged shape. Inner diameter of the preform for mandrel forging is constant, and outer diameter is conical so that it matches the cross-sectional area of the product. However, simulation confirmed that the larger diameter is smaller than predicted and the length is larger than predicted because in the initial stage of forging, the large diameter portion first comes into contact with the anvil at the initial stage of forging and stretches in longitudinal direction. So, it has developed a rule to design the preform considering 3-D deformation instead of plane strain deformation at the beginning stage of mandrel forging. The developed mandrel forging process can be applied to more similar products and economic benefits may be obtained.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.8
• /
• pp.22-27
• /
• 2020

Ring rolling is a type of forging for manufacturing large-diameter rings. Products manufactured by ring rolling are useful in the aerospace industry because of their excellent mechanical properties and high dimensional accuracy. The major components of the ring rolling process are a mandrel and main roll that shape the inside and outside of the ring, an axial roll that shapes the top and bottom of the ring, and a side rolls to position the ring. In this study, a simulation of ring rolling using finite element method (FEM) was performed. DEFORM, a commercial machining analysis program, was used. Based on the simulations, the mandrel feed force required for machining and the drive torque of the main roll were predicted. It was also possible to identify the metal flow caused by machining.

• Transactions of Materials Processing
• /
• v.19 no.6
• /
• pp.329-336
• /
• 2010

Ring forging process is more appropriate for high-length and thin walled ring, because it utilizes the forging press and hence does not require heavy-duty ring rolling mill. Although ring forging process is very simple and economic for facilities, the process is not efficient because of multi-forging-step and low material utilization. An effective ring forging process is developed using a hollow ingot. When a hollow ingot is used with a workpiece, the ingot can be forged into a final ring without multi-stage pre-forging process, such as, cogging, upsetting, and piercing, etc.. Finally it has advantages of the material utilization and process improvement because a few reheating and forging process are not necessary to make workpiece for ring forging. The important design variables are the applied plastic deformation energy to eliminate cast structure and make uniform properties. In this study, the mechanical properties after forging of hollow cast ingot were investigated from the experiment using circumferential sectional model. Also, the effects of process variables were studied by FEM simulation on the basis of thermo-visco-plastic constitutive equation. Applied strain is different at each position in length direction because diameter of hollow ingot is different in length direction. The different strain distribution become into a narrow gap by additional plastic deformation during diameter extension process.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.633-637
• /
• 1995

Numerical calculation tool for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear, sequare spline, internal serrations. A complex calcuation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper, the workpiece with both external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool form combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with other and the calculated solution are useful to predict the capacity of forging equipment.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.2
• /
• pp.81-89
• /
• 1998

Numerical calculation tools for forging of gear-like components based on kinematically admissible velocity fields for upper bound method applicable to various deformation features of workpiece in forging processes were suggested. Each one of them deals with unidirectional flow of metal on dies, such as external involute spur gear. square spline, internal serrations. A complex calculation tool of gear-like component forging process was built up by combining these kinematically velocity fields. In this paper the workpiece with 110th external and internal teeth is divided into two parts. The deformation of each part is analyzed simultaneously using numerical calculation tool from combined kinematically admissible velocity field. The experimental set-up was installed in a 200 ton hydraulic press. As a result, each kinematically admissible velocity field could be combined with others and the calculated solution are useful to predict the capacity of forging equipment.

• Journal of the Korean Society for Precision Engineering
• /
• v.14 no.6
• /
• pp.142-148
• /
• 1997

In this paper, forging of internal triangular and involute serrations are analyzed by upper bound method. Kinematically admissible velocity fields for half pitch of the serration were proposed. It was assumed that the shape flow surface during forging is a straight line perpendicular to plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Experiments were carride out with commercial AI 2024 aluminium alloy. As a result, the calculated solutions are good agreement with experimental results, so it is useful to predict the loads for forging of internal serrations.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.2
• /
• pp.90-98
• /
• 1998

Forging of internal involute gears with alloy steel has been analyzed by means of upper bound method. Kinematically admissible velocity fields for forging of internal gear were proposed. It was assumed that the shape of free flow surface during forging operation is a straight line perpendicular to the plane of symmetry. Using the suggested velocity fields, forging loads and relative pressures were calculated by numerical method. Consequently forging die should be successfully designed without fracture or failure during forging operation. Experiments were carried out with the designed die and SCM415 alloy steel as billet material. The calculated loads were compared with experimental one and they are in good agreement with experimental inspections. As a result, the calculated solutions would be useful to predict the loads and the designed die is suitable for forging of internal involute spur gear with alloy steel. The forged gear is measured to be KS 4 class and its class should be improved by subsequent working such as shaving after forging operation.

• Transactions of Materials Processing
• /
• v.31 no.6
• /
• pp.384-393
• /
• 2022

The flow forming process consists of a split process, a divide process, and a forming process. The split process is a forming process in which rollers radially permeate a simple disc-shaped forging material and split it in both directions to form a top-bottom bidirectional cup. It is advantageous for post-processing to deepen the forming depth in the split process but this characteristic causes the failure near the edge of the mandrel during the actual process. The split process was analyzed using Rigid Plastic FEM, and the stress analysis of the mandrel was conducted to find the cause of the failure. It was found that the failure occurred due to fatigue accumulation damage caused by repeated residual stress.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.06b
• /
• pp.185-194
• /
• 1999

This paper suggests the new techmology to control metal flow in order to reduce the number of preforming and machining for the cold forged product with complex geometry. This technology can be summarized the complex forming, which consists of bulk forming and sheet forming, and multi-action forging, which be preformed double action dies. To analyze the process, finite element simulation has been performed. The proposed technology is applied to hub which is part of air conditioner clutch. According to the result of this study, the relative velocity of mandrel and punch is primary process variable.

• Transactions of Materials Processing
• /
• v.11 no.5
• /
• pp.430-438
• /
• 2002

This paper suggests the new technology to control metal flow in orther to change of the cold forging from conventional deep drawing forming. This technology can be summarized the complex forming, which consists of bulk forming and sheet forming, and multi-action forging, which be performed double action press. The proposed technology is applied to hub clutch model which is part of auto-transmission for automobile. The purpose of this study is to investigate the material flow behavior of hub clutch through control the relative velocity ratio and the stroke of mandrel and punch using the flow forming technique. First of all, the finite element simulations are applied to analyse optimal process conditions to prevent flow defect(necking defect etc.) from non-uniform metal flow, then the results are compared with the plasticine model material experiments. The punch load for real material is predict from similarity law. Finally, the model material experiment results are in good agreement with the FE simulation ones.