Numerical analysis has been carried out to predict the thermal characteristics for a LED lens in mold core system. These thermal characteristics inside the lens are largely affected by geometry, material, and initial conditions of the mold core and lens system. Local temperature and heat flux variation inside the lens are compared for several initial temperatures. Maximum temperature inside the lens was decreased rapidly from the beginning of cooling process up to about 10 seconds. There was also large variation of the heat flux at the upper and lower surfaces of the lens with initial temperature distribution. And the heat flux from the thin lower surface of the lens was relatively higher than the opposite-side thick region. In addition, overall heat transfer rate from the lens through the mold core has similar transient distribution from the beginning. These results can be applied as basic heat transfer data for the LED lens design and manufacturing process in the mold core system.

In this study, mold core of can type lens for optical communication has been fabricated and heat transfer analysis has been conducted. Through this study, results were obtained as follows. Surface roughness of upper and lower cores by ultra precision grinding were Ra 0.002074(um) and 0.004316(um), respectively. Design P-V and Bestfit P-V as shape accuracy of upper core were 0.0858(um) and 0.0843(um), respectively, and those of lower core were 0.0957(um) and 0.0546(um), respectively. The temperatures of upper and lower surfaces of lens during machining obtained by heat transfer analysis were 576.05℃ and 576.4℃, respectively. In case of inner sleeve, it was estimated that the temperature of the side surface were 575.95℃ by heat transferred from lower core. The maximum and minimum temperatures of lower surface of lens were 576.4℃ and 575.96℃, respectively, according to the positions of holes for air circulation from out side.

In this study, mold does not modify the overall. And core was developed as part of a separate. And not detached from the injection mold core part of the device only has to exchange. It has to perform the simulation of resin flow injection. Result of analysis, problems were observed. To create the change core of the four kinds of production prototypes and replace only with the exchange of change core operation of the injection. As a result, there were able to get a products with smooth surface.