Role of die structures on metal flow balance in multi-output porthole extrusion of thin-walled profile

The hypereutectic Aluminum-Silicon (Al-Si) Alloys are gaining impetus in the automotive components, mainly due to their wear resistance. This property in these alloys is derived from the primary silicon crystals. However, there are unique metal flow and mold filling problems associated with hypereutectic Al-Si alloys in Lost Foam Casting (LFC). This investigation is a pioneering work undertaken to gain a better understanding of the role of primary silicon crystals and other phases in the LFC of hypereutectic Al-Si alloys. Time-temperature and first derivative curves were used to determine velocity of metal flow and to calculate solid fractions. Process parameters such as superheat, gating design and alloy composition were manipulated to change the morphology of primary silicon crystals. Microscopy and image analysis of castings enabled study of precipitated particles. Solidification, interlocking and melt sluggishness of precipitated particles significantly influenced fluidity, and the routine process parameters played a minor role.

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Numerical Model Simulation of the Double-Roll Rotary Forging of Large Diameter Thin-Walled Disk

Metals ◽

10.3390/met11111767 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1767

Author(s):

Zhongquan Yu ◽

Mingchao Chen ◽

Chong Ma ◽

Site Luo ◽

Chundong Zhu

Keyword(s):

Numerical Model ◽

Model Simulation ◽

High Surface ◽

Large Diameter ◽

Metal Flow ◽

Deformation Characteristic ◽

Low Noise ◽

Forging Process ◽

Rotary Forging ◽

Thin Walled

Double-roll rotary forging is an emerging plastic forming technology based on rotary forging. Owing to the advantages of being labor-saving, a small eccentric load, low noise and vibration, good uniformity, high surface quality, and material saving, it is very promising for the fabrication of large diameter thin-walled disks. To date, little relevant research on the double-roll rotary forging technology of large diameter thin-walled metal disks has been reported, and the deformation characteristic and the influence of three key parameters on the double-roll rotary forging process remain uninvestigated. Herein, a reasonable 3D rigid-plastic numerical model of the double-roll rotary forging of a disk workpiece is established under the Deform software environment. Based on the valid 3D numerical model, the deformation mechanism, and the effective laws of three key parameters (feed rate v of the lower die, rotational speed n of the upper die, and the initial temperature T of the disk workpiece) on the metal flow and force and power parameters in the double-roll rotary forging process have been explored. The research results provide valuable guidelines for a better understanding of double-roll rotary forging for the fabrication of large diameter thin-walled disks.

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A Design Approach of Porthole Die for Flow Balance in Extrusion of Complex Solid Aluminum Heatsink Profile with Large Variable Wall Thickness

Metals ◽

10.3390/met10050553 ◽

2020 ◽

Vol 10 (5) ◽

pp. 553

Author(s):

Tat-Tai Truong ◽

Quang-Cherng Hsu ◽

Van-Canh Tong ◽

Jinn-Jong Sheu

Keyword(s):

Wall Thickness ◽

Metal Flow ◽

Die Design ◽

Design Approach ◽

Thickness Variation ◽

Extrusion Force ◽

Bridge Structure ◽

Flow Balance ◽

Porthole Die ◽

Wall Thickness Variation

In this study, porthole die used for extrusion of a solid heatsink profile with wall thickness variation ratio up to 15.3 was designed using finite element (FE) simulations. To improve the flow balance in the die, a design approach was introduced to find the appropriate die structure, which includes the porthole and pocket geometry correction, the bearing length adjustment, and the port bridge structure modification. Using the proposed die, the predicted velocity relative difference (VRD) and the maximum velocity difference (ΔV) of extrudate were significantly lower than those of an initial die, which was preliminarily designed based on general design experiences. The required extrusion force and the residual stress in the product were also reduced significantly. Then, the effects of the port bridge structure and welding chamber height on the behavior of the metal flow in the die were investigated. To verify the proposed die design, experimental extrusions were conducted on a 930-ton extruder. The experiment results showed that the extruded product fulfilled the requirements for dimensional tolerances. The design approach presented in this paper can be useful for practical implementation of die design when extruding similar solid heatsink profiles with large wall thickness variation.

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Law of Metal Flow of Thin-Walled Conical Part With Variable Section During Spinning

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2020-23228 ◽

2020 ◽

Author(s):

Shu Xuedao ◽

Xia Yingxiang ◽

Zhu Ying ◽

Li Zixuan ◽

Ye Bohai

Keyword(s):

Metal Flow ◽

Conical Part ◽

Forming Process ◽

Finite Element Software ◽

Axial Tensile ◽

Variable Section ◽

Spinning Process ◽

Thin Walled ◽

Forming Defects

Abstract During the spinning process of the variable-section thin-walled conical parts, the metal flow law is relatively complicated and the flange is prone to be unstable, which resulting in wrinkling and other defects. In this paper, the variable-section conical part of superalloy GH1140 is taken as the research object. The spinning forming process is numerically simulated by using Simufact Finite Element software and the metal flow in each stage of the forming process is analyzed. The flow velocity shows an annular distribution as a whole. The metal near the center of the circle flows more slowly, and the metal far from the circular flange flows more quickly. In the direction of thickness, the velocity of metal flow decreases gradually. Under the feeding action of the roller, the metal in front of the roller is subjected to axial tensile stress, tangential and radial compressive stress, resulting in a strain state of one-way tension and two-way compression. The metal moves along the negative direction of the rotary wheel feed, resulting in the increase of the sheet wall thickness. The correctness of the model in this paper is further verified by spinning experiments. The research results provide a theoretical basis for analyzing the mechanism of forming defects and improving the quality of spinning forming of conical thin-walled parts with variable sections.

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Role of localized heating on the workability of powder metallurgical Al–4% Ti components in cold compression

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/09544062211030305 ◽

2021 ◽

pp. 095440622110303

Author(s):

R Tharmaraj ◽

M Joseph Davidson ◽

S Richard

Keyword(s):

Grain Size ◽

Metal Flow ◽

Structural Components ◽

Cold Upsetting ◽

Damage Site ◽

Novel Technique ◽

Localized Heating ◽

Powder Samples ◽

Upsetting Test

In the present work, localised heating has been adopted at the damage site of the cold upset materials and the role of this mechanism on the workability has been analysed. Cylindrical specimens containing 96% aluminium and 4% titanium were prepared through powder metallurgy technique with an aspect ratio (height to diameter) of 1 by suitable pressures. A series of cold upsetting test was conducted and the material properties for various preforms initial relative densities (80%, 85% and 90%) were determined under the stable strain rate. The flow of metals was analysed using a finite element tool and it was observed that the metal flow starts from near the centre zone to the equatorial zone and the damage happens in the outer position because of more amount of accumulated stresses and the pores. These stresses and pores decrease the workability of the final component. Hence, the present research is intended to reduce the stresses and minimize the pores by applying a localized heating (100 °C–250 °C) at the equatorial sites of the components and thereby increasing the workability of the material. Also, heating selectively at the equatorial site of the workpiece improves the workability due to change in grain size and it was noticed that the grain size of the developed porous preforms was high for the higher heating conditions due to the growth of the grains. Therefore, the localized heating adopted in this work is a superior method to enhance the workability of the powder samples and this novel technique could be useful in improving the workability of the structural components that have extensive applications in the automobile and aerospace industries.

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Development of Fibre-Cement Composites with Self-Cleaning and de-NOx Ability

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1124.123 ◽

2015 ◽

Vol 1124 ◽

pp. 123-129

Author(s):

Martin Bohac ◽

René Čechmánek ◽

Theodor Staněk

Keyword(s):

Portland Cement ◽

Cement Composites ◽

Composite Binder ◽

Fibre Cement ◽

Thin Walled ◽

Self Cleaning ◽

White Portland Cement

Paper deals with development of face architectural fibre-cement composites based on white Portland cement with addition of photoactive TiO2. Tests were carried on composite binder and then on the composites. The role of TiO2 on performance of materials was monitored. Selected composites were tested on self-cleaning ability, de-NOx activity and resistance to weathering in outdoor conditions. Two series of thin-walled products based on developed composites were prepared with self-cleaning ability and de-NOx activity.

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Application of Numerical Simulation in Stamping Process of Complex Box-Type Parts

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.291-294.579 ◽

2011 ◽

Vol 291-294 ◽

pp. 579-584 ◽

Cited By ~ 1

Author(s):

Guang Kai Wang ◽

Si Yuan Cheng ◽

Su Yang Li ◽

Xiang Wei Zhang

Keyword(s):

Numerical Simulation ◽

Metal Flow ◽

Design Parameters ◽

Simulation Technology ◽

Forming Process ◽

Stamping Process ◽

Accurate Forecast ◽

Blank Holding Force ◽

Process Prediction

Due to the recent development both in the numerical simulation technology and computer technology, the role of numerical simulation in sheet forming industry has been continuously increasing in recent years. This paper describes the application of numerical simulation technology in the forming process of a complex box-type part with Dynaform and gives a fairly accurate forecast of defects that may appear in the forming process. Prediction of the effect of design parameters such as blank holding force and drawbeads on forming quality is investigated. The study indicates that blank holding force and drawbead directly affect the metal flow and formability of stamping. Then, by adjusting blank holding force and setting appropriate drawbeads, an optimized stamping process plan is obtained and is validated in experiments. Finally the phenomenon and displacement of distortion springback are predicted in the springback simulation, which is useful to further improve the quality of this kind of part.

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