Injection Molded Microcellular Plastic Gear (I) - Process Design for the Microcellular Plastic Gear -

초미세발포 플라스틱 기어에 관한 연구 (I) - 초미세발포 플라스틱 기어의 공정설계 -

  • 하영욱 (한양대학교 대학원 기계설계학과) ;
  • 정태형 (한양대학교 기계공학과)
  • Published : 2005.05.01


This research Proposes a Process design of injection molded microcellular plastic gears for enhancing the fatigue strength/durability and accuracy of the gears applying thermodynamic instability to microcellular foaming process. To develop the injection molded plastic gears by way of microceliular process, it is absolutely necessary the following two process design. The first is microcellular forming process for enhancing the strength/durability of plastic gears. To be microcellular process succeeded, based on the microcellular principle, mechanical apparatus is designed where nucleation and cell growth are to be generated renewably. The second is the counter pressure process which is mainly fur improving the tooth surface roughness and the accuracy of microcellular gears. For the former process, screw, nozzle and gas equipment are newly designed, and for the latter, counter pressure by nitrogen gas is intentionally brought about into mold cavity when injecting plastic gears. Based on the proposed process design, using gear mold, experiments of injection molding show that, in internal space of plastic gears, microcellular nuclear cells less than 5 lim in diameter have been generated homogeneously via electron microscope photos.


Gear;Microcellular Plastic Cear;Fatigue Strength;Gear Accuracy;Thermodynamic Instability;Nucleation;Cell Growth;Counter Pressure


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