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Technical Brief

Variable Distance Adjustment for Conformal Cooling Channel Design in Rapid Tool

[+] Author and Article Information
K. M. Au

Department of Industrial and Systems Engineering,
The Hong Kong Polytechnic University,
Hung Hom,
Kowloon 852, Hong Kong
e-mail: akm_kenneth@yahoo.com.hk

K. M. Yu

EF603, Department of Industrial and Systems Engineering,
The Hong Kong Polytechnic University,
Hung Hom,
Kowloon 852, Hong Kong
e-mail: km.yu@polyu.edu.hk

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received December 29, 2010; final manuscript received January 7, 2014; published online May 21, 2014. Assoc. Editor: Yong Huang.

J. Manuf. Sci. Eng 136(4), 044501 (May 21, 2014) (9 pages) Paper No: MANU-10-1393; doi: 10.1115/1.4026494 History: Received December 29, 2010; Revised January 07, 2014

During thermoplastic injection moulding process, the gradual increase of the coolant temperature along the conformal cooling channel (CCC) inside the rapid tool reduces the rate of heat transfer from the polymeric melt to the cooling channel surface at the outlet portion. Injection moulded defects such as irregular warpage of the part between the coolant inlet and outlet cannot be avoided. Rapid tooling (RT) technology offers a speedy and automatic method for rapid tool design and fabrication integrated with complex internal structure such as CCC. This paper presents a novel adjustment method for cooling distance modification between the CCC and its mould cavity (or core) surface along the cooling channel. The proposed method can compensate the gradual increase of the coolant temperature from the coolant inlet to the coolant outlet. More heat can be transferred from the mould surface near the coolant outlet to the proposed variable distance conformal cooling channel (VDCCC). In this study, the cooling channel distance modification relies on two adjustment attributes: (1) the adjustment direction and (2) the adjustment amount, between the mould cavity (or core) surface (terrain) and the cooling channel axis (polyline) after the linearized approximation. A computer-aided melt flow analysis tool of moldflow plastics insight is employed in the case study in order to demonstrate the feasibility of the proposed method. The cooling performance of the proposed VDCCC design can be verified.

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References

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Figures

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Fig. 1

Temperature variation between the coolant inlet and the coolant outlet

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Fig. 2

Conventional CCC (a) CCC with variable distance (b)

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Fig. 3

Workflow of the proposed adjustment method

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Fig. 4

Relationship between the parting and the heat transfer directions

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Fig. 5

Normal offsetting of a mould surface

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Fig. 6

Cooling channel axis on the offset mould surface

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Fig. 7

Cooling channel axis above the M→(u,v)

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Fig. 8

Tangent plane of the cooling channel axis cutting the mould surface

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Fig. 9

Linearized approximation of the mould surface and the cooling channel axis

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Fig. 10

Approximation of curve on mould surface into polyline (straight line) segment

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Fig. 11

Possible AiJij→ on I→i (a) and adjustment a∧ on I→i(b)

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Fig. 12

Adjustment a∧ on the I→i

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Fig. 13

Adjustment amount for the new axis position of the A→'

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Fig. 14

A→' the for new cooling channel axis formation

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Fig. 15

A→ (axis for CCC) and A→' (axis for the VDCCC) at side view

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Fig. 16

(a) VDCCC and (b) CCC and VDCCC with generation

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Fig. 17

(a) CAD mould surface model, (b) normal offsetting, (c) the cooling channel axis creation, and (d) the cooling channel axis extraction for the proposed adjustment

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Fig. 18

(a) Linearized approximation between the mould surface model and the cooling channel axis and (b) adjustment of the cooling channel axis by the cutting plane

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Fig. 19

Comparison of the geometric designs between the conventional CCC and the VDCCC in MPI 3.1, (a) trimetric view and (b) side view

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Fig. 20

Comparison of conventional CCC and the VDCCC (designs after the mesh generation process in MPI

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Fig. 21

Maximum part temperature,  °C, (a) the conventional CCC and (b) the proposed VDCCC

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Fig. 22

Average temperature, part  °C, (a) the conventional CCC and (b) the proposed VDCCC

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Fig. 23

Volumetric shrinkage, %, (a) the conventional CCC and (b) the proposed VDCCC

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Fig. 24

Average temperatures, part at different positions on the mould surface, (a) CCC and (b) VDCCC

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Fig. 25

The plot of average temperatures, part against different cooling channel positions between the CCC and the VDCCC

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