| Summary: | 碩士 === 國立高雄應用科技大學 === 模具系碩士在職專班 === 101 === Industry demands for thinner and lighter mainstream product design has gradually become the mainstream product design, starting with the advantage of a thin light guide panel.
Thin light guide plate’s high rate of fire, high injection pressure for filling time, will result in the die wall to near the epidermis. The velocity gradient is too large, resulting in significant shear effects. This includes molecular chains with isotropic shear caused by excessive friction. The heat caused by the friction will melt the of glue inferior solutions.
These phenomena directly affect the finished quality and overall mechanical properties of the finished surface. The end product shortcomings include scratches and a decrease in tensile strength.
In this study, the 11-inch thickness 0.6mm light guide plates are installed in the mold cavity pressure sensors (public mode) and temperature sensor (female mold). By touching the two sensors, calculations of melt time difference and melt pressure loss measure the melt in the mold cavity shear properties, such as shear stress, shear rate, and viscosity.
Poly Methyl Methacrylate (PMMA) for the plastic, after forming the light guide plate to a scratch test， The surface of the light guide plate profilometer measurements were at different locations (near and far from the gate to the gate), "vertical" and "horizontal ".
The finished surface scratches depth to explore the molecular alignment melt and shear properties on the surface quality of the light guide plate (LGP), The use of the single-target Taguchi method and multi-objective method respectively, look small as the goal. It is best made from a combination of parameters.
Different conditions of the finished product occurred after molding from a scratch testing machine. Surface profiler LGP different locations were measured (near and far gate to gate). "Horizontal" and "vertical" scratches the surface of the depth of the melt probed the molecular alignment and shear properties of the surface quality of the finished product.
The results showed impact from four different LGP locations (near and far gate, horizontal and vertical) and depth scratches for important factors "mold temperature" and "injection speed". 70% of the contribution focused on the display surface scratches molded skin layer (Skin Layer) generated thickness.
Far from the deepest scratches the gate, thin products must overcome
high shear heat generation problems. Therefore, the parameters used for the surface quality when high-speed injection causes scratches at the gate. This is because of the high shear effect of high-speed filling time prone to frictional heat, thermal cracking of molecules, and the formation of small molecules.
Because of the high shear effect of long molecules being cut leaves a small molecule, causing the shear rate to increase, the phenomenon is more evident at the end. The surface will move a small molecule and therefore resulting in deeper scratches。
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