A study on monitoring for process time and process properties by measuring vibration signals transmitted to the mold during injection molding

사출성형공정에서 금형에 전달되는 진동 신호 측정을 이용한 성형 단계별 공정시간과 공정특성의 모니터링에 대한 연구

  • Lee, Jun-han (Research Institute of Advanced Manufacturing & Materials Technology Shape Manufacturing R&D Department. Korea Institute of Industrial Technology) ;
  • Kim, Jong-Sun (Research Institute of Advanced Manufacturing & Materials Technology Shape Manufacturing R&D Department. Korea Institute of Industrial Technology)
  • 이준한 (한국생산기술연구원 형상제조연구부문) ;
  • 김종선 (한국생산기술연구원 형상제조연구부문)
  • Received : 2020.08.06
  • Accepted : 2020.09.30
  • Published : 2020.09.30

Abstract

In this study, the vibration signal of the mold was measured and analyzed to monitoring the process time and characteristics during injection molding. A 5 inch light guide plate mold was used to injection molding and the vibration signal was measured by MPU6050 acceleration sensor module attached the surface of fixed mold base. Conditions except for injection speed and packing pressure were set to the same value and the change of the vibration signal of the mold according to injection speed and packing pressure was analyzed. As a result, the vibration signal had a large change at three points: "Injection start", "V/P switchover", and "Packing end". The time difference between "injection start" and "V/P switchover" means the injection time in the injection molding process, and the time difference between "V/P switchover" and "Packing end" means the packing time. When the injection time and packing time obtained from the vibration signal of the mold are compared with the time recorded in the injection molding machine, the error of the injection time was 2.19±0.69% and the error of the packing time was 1.39±0.83%, which was the same level as the actual value. Additionally, the amplitude at the time of "injection start" increased as the injection speed increased. In "V/P switchover", the amplitude tended to be proportional to the pressure difference between the maximum injection pressure and the packing pressure and the amplitude at the "packing end" tended to the pressure difference between the packing pressure and the back pressure. Therefore, based on the result of this study, the injection time and packing time of each cycle can be monitored by measuring the vibration signal of the mold. Also, it was confirmed that the level and trend of process variables such as the injection speed, maximum injection pressure, and packing pressure can be evaluated as the change of the mold vibration during injection molding.

References

  1. Shin, B. D., and Oh, H. J., "A Study on Quality Classification of Injection Molding Process by Kalman Filter" KIPS Tr. Software and Data Eng., Vol. 5, No. 12, pp. 635-640, 2016. https://doi.org/10.3745/KTSDE.2016.5.12.635
  2. Hassan, H, "An experimental work on the effect of injection molding parameters on the cavity pressure and product weight", Int. J. Adv. Manuf. Technol., Vol. 67, pp. 675-686, 2013. https://doi.org/10.1007/s00170-012-4514-4
  3. Noh, K. C, Lee, G. H., Jang, M. K., and Jeong, Y.D., "Realation of Injection Temperature and Weld-quality in Injection Molding" J. D&M Eng., Vol. 9, No. 1, pp. 27-30, 2015.
  4. Michaeli, W., and Schreiber, A. "Online Control of the Injection Molding Process Based on Process Variables", Adv. Polym. Tech., Vol. 28, No. 2, pp. 65-76, 2002. https://doi.org/10.1002/adv.20153
  5. Zhou, X., Zhang, Y., Mao, T., and Zhou, H., A. "Monitoring and dynamic control of quality stability for injection molding process", J. Mater. Process. Technol., Vol. 46, No. 7, pp. 844-852, 2006.
  6. Cox, H. W., and Mentzer, C. C. "Injection Molding:The Effect of Fill Time on Properties", Polym. Eng. Sci., Vol. 26, No. 7, pp. 488-498, 1986. https://doi.org/10.1002/pen.760260707
  7. Huh, J. D., and Song, Y. H., "Effect of Injection Time, Filling Pressure, and Holding Time on Injection-molded Lens Parts", Korean J. Rheol., Vol. 4, No. 2, pp. 116-126, 1992.
  8. Woo, S. W., and Park, S. H., "Effects of Packing Pressure and Time on Injection Molding of Plastic Micro-channel Plates", J. Korean Soc. Manuf. Technol. Eng., Vol. 25, No. 3, pp. 224-229, 2016. https://doi.org/10.7735/ksmte.2016.25.3.224