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Research Papers

A Proposed Technique to Acquire Cavity Pressure Using a Surface Strain Sensor During Injection-Compression Molding

[+] Author and Article Information
Han-Xiong Huang

e-mail: mmhuang@scut.edu.cn
Center for Polymer Processing
Equipment and Intellectualization,
The Key Laboratory of Polymer Processing Engineering of the Ministry of Education,
South China University of Technology,
Guangzhou 510640, PRC

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the Journal of Manufacturing Science and Engineering. Manuscript received November 15, 2011; final manuscript received December 26, 2012; published online March 22, 2013. Assoc. Editor: Robert Gao.

J. Manuf. Sci. Eng 135(2), 021003 (Mar 22, 2013) (6 pages) Paper No: MANU-11-1362; doi: 10.1115/1.4023376 History: Received November 15, 2011; Revised December 26, 2012

A new technique was proposed and experimentally verified for the cavity pressure acquisition in the injection-compression molding (ICM). The surface strain of the fixed mold half and the cavity pressure were monitored simultaneously during ICM. In the compression stage, a directly proportional relationship between the cavity pressure and mold surface strain was found and determined via the regression analysis. By taking the advantage of this relationship, the cavity pressure profile with high accuracy was indirectly obtained from the nondestructive measurement of the mold surface strain. Moreover, the mold surface strain profile could indicate the part weight or thickness and the critical time when the part surface lost contact with the cavity surface in a large area. The monitoring of the mold surface strain could serve as an interesting alternative to the direct monitoring of the cavity pressure with respect to process and part quality control for ICM.

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Figures

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Fig. 2

Profiles of (a)–(d) cavity pressures at P1 and P2 and (e)–(h) mold surface strain during ICM under varied processing parameters

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Fig. 1

Schematic of fixed mold half equipped with cavity pressure sensors and surface strain sensor (unit: mm)

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Fig. 3

Result of regression analysis for relationship between peak cavity pressure at P1 and peak mold strain monitored in compression stage

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Fig. 4

Representative cavity pressure profiles directly measured at P1 and obtained from strain sensor in compression stage (test no. 2)

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Fig. 5

Cavity pressure profiles measured with pressure sensor at P1 and obtained from strain sensor in compression stage under optimized molding conditions. Injection stroke: 20.8 mm, compression force: 150 kN, compression stroke: 3 mm, compression speed: 35 mm/s.

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Fig. 6

Part weight and thickness under varied injection strokes. Compression force: 100 kN, compression stroke: 2 mm, compression speed: 20 mm/s.

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