目前射出成型機的螺桿加熱系統，多半採用較為傳統的電阻加熱方式，不僅所需的加熱時間較長，升溫的速率較慢，且會造成較大的能量損失。現利用感應加熱技術於螺桿加熱系統，可以解決上述提到電阻加熱方式遇到的問題，但是利用感應加熱方式來加熱螺桿，會造成其加熱的螺桿表面溫度分布不均勻，將是所需解決的首要問題。
本研究發展出使用感應加熱方式來取代傳統電阻加熱方式，並且藉由設計感應加熱的線圈部份來解決螺桿表面溫度分布不均勻的問題。首先，探討如何調整感應線圈的間距，以及需要放置多少導磁塊的方法；另外，透過實驗得到如何調整導磁塊在感應線圈上的間距分布，以得到穩定的磁通量，進而達到加熱溫度在螺桿表面的均勻分布。最後透過分析軟體(ANSYS)來分析不同間距的導磁塊所影響的加熱效果。本研究經由模擬分析發現，當改變螺桿直徑，以及調整感應加熱系統的頻率，不會影響螺桿表面溫度分布的問題。藉由實驗以及模擬分析結果發現，當使用感應加熱方式配合本研究建議的感應線圈組合方式，不僅可以有效降低加熱時間，其加熱速率也較電阻加熱方式快，並且達到與使用電阻加熱方式時相同的溫度均勻分布；若在感應線圈上的導磁塊相互間距為8 mm時，可以達到最均勻的溫度分布。此方式可以實際應用於射出成型機的加熱系統。

In an injection molding machine, the conventional barrel heating system which uses resistance heating method (RH), has some drawbacks such as low heating rate, long heating time, and energy loss. With induction heating (IH) technique, the barrel can better almost all of these disadvantages. However, non-uniform temperature distribution on inside surface of a barrel is the main drawback of induction heaters.
In this thesis, a barrel heating system was developed using induction heating instead of resistance heating. And, to design a induction coil for the induction heating system so that the barrel has uniform temperature distribution. Firstly, methods of adjusting the pitch of turns of working coil and adding magnetic flux concentrators would be developed. Secondly, a working coil coupled with magnetic flux concentrators via adjustment of magnetic flux concentrator spacing to achieve uniformity of magnetic flux and temperature distribution on the inside surface of a barrel was proposed and experimented. Finally, Different pitches of magnetic flux concentrators were applied to study the uniform heating capability of induction heating system with heating coil coupled with magnetic flux concentrators via commercial software, ANSYS. In addition, changing diameters of a barrel and varying operation frequency of induction power supply were investigated to effects o uniform temperature distribution at the inside surface of the barrel. Results showed that, when barrel was heated by induction heating method with the proposed induction heating coil, heating time to reach a specific temperature could be reduced, and heating rate increased compared to resistance heating method. With 8 mm pitch of magnetic flux concentrators on a coil, the temperature distribution was the most uniform. The results from simulation and experiment agreed well. Simulation results showed that, changing diameters of a barrel or varying operation frequency of induction power supply had no effect on uniform temperature distribution at the inside surface of the barrel. Under proper design of working coil, the barrel heating system by induction method can achieve the same uniform temperature distribution as the barrel heated by resistance method, and could be practically used in an injection molding machine.

1. P. C. Chang and S. J. Hwang, “Simulation of infrared rapid surface heating for injection molding,” International Journal of Heat and Mass Transfer, 49, 3846-3854 (2006).
2. M. C. Jeng, S. C. Chen, S. M. Pham, J. A. Chang and C. S. Chung, “Rapid mold temperature control in injection molding by steam heating,” International Communications in Heat and Mass Transfer, 37, 1295-1304 (2010).
3. S. C. Chen, W. R. Jong and J. A. Chang, “Dynamic mold surface temperature control using induction heating and its effects on the surface appearance of weld line,” Journal of Applied Polymer Science, 101, 1174-1180 (2006).
4. S. C. Chen, W. R. Jong, Y. J. Chang, J. A. Chang and J. C. Cin, “Rapid mold temperature variation for assisting the micro injection of high aspect ratio micro-feature parts using induction heating technology,” Journal of Micromechanics and Microengineering, 16, 1783-1791 (2006).
5. Y. T. Cai, Development of uniform surface induction heating system for rapid mold and hot runner heating, Master thesis, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan (2011).
6. J. C. Li, Development of electromagnetic induction heating system for rapid molding heating, Master thesis, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan (2010).
7. M. S. Tran, Experiment and simulation of induction heating system for injection molding machine barrel, Master thesis, Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan (2012).
8. G. A. Campbell, Modern plastics encyclopedia for 1968-69, McGraw-Hill Inc, New York (1968).
9. K. G. Yao, F. R. Gao and F. Allgöwer, “Barrel temperature control during operation transition in injection molding,” Control Engineering Practice, 16, 1259-1264 (2008).
10. I. Shibata and T. Uchida, Hot-runner plastic injection molding system, Patent 4726751-A, USA (1988).
11. W. J. Lai and S. Chen, “The control research of neural network on barrel temperature of the plastic injection molding machine,” Applied Mechanics and Material, 52, 1656-1659 (2011).
12. V. Rudnev, D. Loveless at el., Handbook of induction heating, Marcel Dekker, Inc (2003).
13. J. I. Pilavdzic, S. V. Buren and V. G. Kagan, Apparatus for inductive and resistive heating of an object, Patent 7041944-B2, USA (2006).
14. P. E. Burke, Induction heating and melting systems having improved induction coil, Patent 4874916-A, USA (1989).
15. B. Taylor, T. Womer and R. Kadykowski, “Efficiency gains and improvements using different barrel heating technologies for the injection molding process,” In: ANTEC Conference Proceedings, 2429-2433 (2007).
16. S. J. Chang, P. C. Xie, X. T. He and W. M. Yang, “Numerical simulation of temperature field in barrel of injection molding machine during induction heating process based on ANSYS software,” Advanced Material Research, 87, 16-21 (2009).
17. S. Zinn and S. L. Semiatin, Elements of induction heating: design, control and application, ASM International (1988).
18. E. Wrona, B. Nacke and D. Resetov, “3D modeling of the transient heating process for induction surface hardening,” International Scientific Colloquium, Hannover, Germany (2003).
19. S. Moaveni, Finite element analysis: theory and application with ANSYS, New Jersey: Pretice-Hall, Inc. (1999).
20. Release 10.0 Documentation for ANSYS: SAS IP, Inc. (2005).
21. M. Kranjc, A. Zupanic, D. Miklavcic and T. Jarm, “Numerical analysis and thermographic investigation of induction heating,” International Journal of Heat and Mass Transfer, 53, 3585-3591 (2010).
22. C. G. Kang, P. K. Seo and H. K. Jung, “Numerical analysis by new proposed coil design method in induction heating process for semi-solid forming and its experimental verification with globalization evaluation,” Material Science Engineering A, 341, 121-138 (2003).
23. A. Boadi, Y. Tsuchida, T. Todaka and M. Enokizono, “Designing of suitable construction of high frequency induction heating coil by using finite element method,” IEEE Transaction Magnetics, 41, 4048-4050 (2005).
24. T. Todaka and M. Enokizono, “Optimal design method with the boundary element for high-frequency quenching coil,” IEEE Transaction Magnetics, 32, 1262-1265 (1996).
25. M. S. Huang and Y. L. Huang, “Effect of multi-layered induction coils on efficiency and uniformity of surface heating,” International Journal of Heat and Mass Transfer, 53, 2414-2423 (2010).