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High performance cooling system of the die cast dies

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Objectives:1. Improve performance of the die cast die cooling system2. Reduce soldering of the die components3. Reduce solidification shrinkage defects3. Improve micro-structure of the casting

High performance cooling system of the die cast dies

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Typical cooling system layout

High performance cooling system of the die cast dies

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Stages of the boiling process

Convective heat transfer mode

Nucleate boiling Steam jetsare forming

Neighboring vapor jets merge

Most of the surface of the heated wall is covered with vapor

High performance cooling system of the die cast dies

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Heat transfer coefficient distribution along the channel length

Zone I Convection heat transferZone II Nucleate boiling Zone III Most of the surface of the heated wall is covered with vaporZone IV Transition boilingZone V Film boiling

High performance cooling system of the die cast dies

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There are substantial differences between the two phase flow in micro-channels and conventional cooling channels

1. Surface tension force has a more pronounced influence on the flow.

2. Bubbly flow can be rarely observed because bubbles grow and quickly reach size of the channel.

3. Due to small size of the channel Taylor instability doesn’t occur in the micro-channels.

High performance cooling system of the die cast dies

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Boiling in thin channel

Zone I Convection heat transferZone II Nucleate boiling Zone III Most of the surface of the heated wall is covered with vaporZone IV Transition boilingZone V Film boiling

High performance cooling system of the die cast dies

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Full shot with core

High performance cooling system of the die cast dies

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Core with micro-channel cooling

High performance cooling system of the die cast dies

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Stress analysis of the core(dyne/cm^2)

High performance cooling system of the die cast dies

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Temperature distribution in the core(Before spray)

High performance cooling system of the die cast dies

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Core after 6,000 shots

High performance cooling system of the die cast dies

Old cooling channel design Micro-channel cooling design

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Heat transfer coefficient for micro-channel cooling

Heat transfer coefficient is found by a superposition of the nucleateboiling and forced convection components1.

High performance cooling system of the die cast dies

spnb FhShh

Where,S - suppression factorhnb - nucleate boiling heat transfer coefficientF - enhancement factorhsp - single phase heat transfer coefficient

1. J.C. Chen, Correlation for boiling heat transfer to saturated fluids in convective flow, Industrial and Engineering Chemistry – Process Design and Development5 (3) (1966) 322–329.

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Verification of the numerical analysis results

High performance cooling system of the die cast dies

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High performance cooling system of the die cast dies

Smaller core with cooling(Dia. 12 mm)

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High performance cooling system of the die cast dies

Smaller core with cooling(Dia. 12 mm)

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High performance cooling system of the die cast dies

Rib insert with micro-channel cooling

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High performance cooling system of the die cast dies

Old cooling line design Micro-channel cooling

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High performance cooling system of the die cast dies

Conclusions

1.Three dimensional micro-channel cooling is an affective high capacity thermal management method. It can support high heat transfer rates from the liquid metal during metal flow and solidification.2.Reduction in core heat resistance as well as increase of thermal capacity of the cooling system, allows support of higher heat flux without over-heating of the core3.New cooling design concepts allowed further reduction or even elimination of die soldering, casting surface defects, and excessive external cooling while reducing cycle time and cost

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High performance cooling system of the die cast dies

Questions?