Study on Quality Improvement Techniques for Injection-Molding of Polymer Utilizing Heat Transfer Control

在这项研究中，聚合物材料的辐射加热作为主动控制技术的moldedpolymer在模具内的冷却进行了研究。为了阻止注射到冷模腔中的聚合物熔体的冷却，在注射成型过程的充模阶段，利用CO2激光器对模腔中的聚合物熔体进行加热，研究了辐射加热对成型聚合物质量的影响。（1）辐射加热技术对制品质量的改善：采用辐射加热技术制备了聚苯乙烯条，并对成型制品的质量进行了研究。由于辐射加热对冷却的阻碍，减少了由于聚合物熔体在充模过程中的凝固而引起的缺陷，如凝固在塑带表面区域的残余双折射、由于聚合物熔体粘度增加而产生的短射、塑带表面的可转印性降低等。(2)红外激光辐照聚合物的温度分布：红外辐射辐照聚合物熔体的温度分布由聚合物内的辐射吸收和与冷模壁接触引起的传导冷却之间的关系决定。为了获得对辐射条件下的温度分布的理解，聚合物内的传热进行了数值研究。结果表明，聚合物材料的单色吸收系数与加热红外辐射的波长分布之间的关系对成型聚合物内的温度有很大的影响，在实际条件下，红外辐射的加热效应穿透距离聚合物表面约0.5 ~ 1 mm。

In this study, radiation heating of the polymeric materials was investigated as the active controlling technique for cooling of moldedpolymer within the mold. In order to obstruct the cooling of polymer melt injected into the cold mold cavity, polymer melt in the cavity was heated by using CO2 laser during the filling stage of the injection-molding process, and the effects of radiation heating on the quality of molded polymer was experimentally examined. The results can be summarized as follows :(1) Quality Improvement due to Radiation Heating : Radiation heating technique was adoptedto produce a polystirene strip, and the quality of molded polymer was investigated. The obstruction of cooling due to radiation heating results in reducing the failures originated from solidification of polymer melt during the filling stage, such as residual birefringence frozen in surface region of molded strip, short-shot due to increasing the viscosity of polymer melt, lowering the transcribability of strip surface, etc.(2) Temperature Profiles in the Polymer Irradiatedby InfraredLaser : Temperatureprofile within the polymer melt irradiatedby infraredradiation is determinedby the relation between radiation absorption within the polymer and conductive cooling due to contact with the cold mold wall. In order to obtain the understandings about the temperature profiles under the irradiation condition, heat transfer within the polymer was numerically examined. The results showed that the temperature within the molded polymer is strongly affected by the relation between the monochromatic absorption coefficient of polymer material and wavelength distribution of the heating infraredradiation, and that, under the realistic condition, heating effect due to infraredradiation penetrates about 0.5-1mm from the polymer surface.