Water assisted injection moulding: development of insights and predictive capabilities through experiments on instrumented process in parallel with computer simulations
Water assisted injection moulding: development of insights and predictive capabilities through experiments on instrumented process in parallel with computer simulations
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DOI：
10.1179/174328908x283438
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
A. Polynkin;L. Bai;J. Pittman;J. Sienz;L. Mulvaney-Johnson;E. Brown;A. J. Dawson;P. Coates;B. Brookshaw;K. Vinning;J. Butler
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文献类型：
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作者：
A. Polynkin;L. Bai;J. Pittman;J. Sienz;L. Mulvaney-Johnson;E. Brown;A. J. Dawson;P. Coates;B. Brookshaw;K. Vinning;J. Butler
建立了理想的水辅注射成型(WAIM)脱芯模型，以隔离水冷却对熔覆层厚度的影响。在模拟的基础上，针对一个具体的案例，研究了它作为皮尔逊数和幂指数的函数。研究发现，冷却可以显著降低气泡的厚度，使气泡前的流型从旁通流变为再循环流成为可能。对于粘性温度系数较高的剪切变稀熔体，模拟结果表明熔体厚度很小，这可能预示着WAIM的不利条件。虽然在真实的造型情况下，其他影响将叠加在这里发现的影响上，但结果为WAIM的基本原理提供了新的见解。对以傅立叶数和雷诺数为特征的其他效应的调查将在随后报道。给出了实验WAIM模具的早期工艺测量结果。随着注水设定压力的增加，残余壁厚减小，并通过实验确定了水泡穿过熔体的持续时间。随着注水压力的增加，残余壁内空洞的形成被注意到并观察到严重程度减轻。这种空洞的存在可以通过来自红外温度传感器的签名来检测。
An idealised model of core-out in water assisted injection moulding (WAIM) is set up to isolate the effect of cooling by the water on the deposited layer thickness. Based on simulations, this is investigated for a specific case as a function of Pearson number and power law index. It is found that cooling significantly reduces the layer thickness to the extent that a change in the flow regime ahead of the bubble, from bypass to recirculating flow, is possible. For shear thinning melts with high temperature coefficient of viscosity, the simulations show very low layer thickness, which may indicate unfavourable conditions for WAIM. Although in the real moulding situation, other effects will be superimposed on those found here, the results provide new insights into the fundamentals of WAIM. Investigation of other effects characterised by Fourier and Reynolds numbers will be reported subsequently. Some early process measurement results from an experimental WAIM mould are presented. Reductions in residual wall thickness are observed as the water injection set pressure is increased and the duration of water bubble penetration through the melt is determined experimentally. The formation of voids within the residual wall is noted and observed to reduce in severity with increasing water injection pressure. The presence of such voids can be detected by the signature from an infrared temperatures sensor.