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

Tat-Tai Truong,Quang-Cherng Hsu,Van-Canh Tong,Jinn-Jong Sheu

doi:10.3390/met10050553

Tat-Tai Truong, Quang-Cherng Hsu + Show 2 more

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https://doi.org/10.3390/met10050553

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Abstract

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.

Highlights

Aluminum alloys are increasingly used in many industrial fields because of their advantages namely, lightweight, high specific strength, good formability, high thermal conductivity, and corrosion resistant
The flow velocity distribution during extrusion is a crucial factor that determines the success of an extrusion process
The quality of velocity distribution can be monitored through several parameters such as the standard deviation of velocity (SDV) [18] or the velocity relative difference (VRD) [20]

Summary

Introduction

Aluminum alloys are increasingly used in many industrial fields because of their advantages namely, lightweight, high specific strength, good formability, high thermal conductivity, and corrosion resistant. Hot extrusion is an economical process, which has been widely used to manufacture many aluminum alloys products [1]. Aluminum heatsink products can be found in many cooling devices such as CPU coolers, radiators of light-emitting diode (LED) or high-performance electronic systems, etc. There are two basic types of aluminum heatsink profiles, which include solid and hollow profiles. The geometry of solid profiles is commonly complex, with long fins and variable wall thickness. Increasing the complexity of extruded profiles makes the die design process more challenging Aluminum heatsink products can be found in many cooling devices such as CPU coolers, radiators of light-emitting diode (LED) or high-performance electronic systems, etc. [2].

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