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Study on Travelling Magnetic Field Casting of Sheet

Study on Travelling Magnetic Field Casting of Sheet. Guo Jingjie, Su Yanqing, Bi Weisheng, Zhang Tiejun, Huang Junyong, Jia Jun, Fu Hengzhi. School of Materials Science and Engineering Harbin Institute of Technology, Harbin 150001, P.R. China. HIT. OUTLINE 1.OBJECTIVE

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Study on Travelling Magnetic Field Casting of Sheet

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  1. Study on Travelling Magnetic Field Casting of Sheet Guo Jingjie, Su Yanqing, Bi Weisheng, Zhang Tiejun, Huang Junyong, Jia Jun, Fu Hengzhi School of Materials Science and Engineering Harbin Institute of Technology, Harbin 150001, P.R. China

  2. HIT OUTLINE 1.OBJECTIVE 2.EXPERIMENTAL EQUIPMENT 3.MAGNETIC FIELD INTENSITY 4.MOULD-FILLING EXPERIMENT 5.MAIN DEFECTS 6.CONCLUSIONS

  3. HIT 1.OBJECTIVE Main problems casting thin wall cast -ings: Very high cooling rate results in low mould-filling ability Objective of this paper :Improve filling mould ability

  4. HIT 2.EXPERIMENTAL EQUIPMENT

  5. HIT 1-kickstand 2-iron core 3-fastener 4-pouring basin 5-windings 6-magnetic yoke 7-molten metal 8-cope 9-drag 10-transformer Fig. 1 Illustration of a TMFC equipment and the photo of the inductor

  6. HIT 3.MAGNETIC FIELD INTENSITY

  7. z ABCDEF y x HIT Fig.2 X-Y-Z coordinated system on the inductor and the positions of points A to F.

  8. HIT Fig.3 Distribution of magnetic field intensity (z=5mm, ampere-turns is 1272At)

  9. HIT Fig.4 Changes of magnetic field intensity with height (ampere-turns is 1272At) and with ampere-turns (z=5mm) in z direction of point A and F

  10. HIT Fig.5 The influence of cope materials on magnetic field intensity of point A

  11. HIT Fig.6 Distribution of By and Bz at y-z plane

  12. HIT Fig.7 Isoline for By and Bz over the inductor

  13. HIT Fig.8 Simulation result of travelling magnetic field(2Poles)

  14. HIT Fig.8 Simulation result of travelling magnetic field (1Pole)

  15. HIT Fig.8 Simulation result of travelling magnetic field (coil turns decrease)

  16. HIT Fig.8 Simulation result of travelling magnetic field (2inductors)

  17. HIT 4. MOULD-FILLING EXPERIMENT

  18. HIT Fig.9 Experimental method to measure the equivalent pressure head

  19. 55 50 45 40 with ferromagnetic cope 35 30 Pressure head / mm 25 20 with ferromagnetic cope 15 10 5 600 800 1000 1200 1400 1600 1800 Ampere-turns / At HIT Fig.10 The equivalent pressure head change with magnetic field intensity

  20. HIT 1-computer, 2-camera, 3-gallium melt, 4-plunger, 5-induction coil, 6-mould cavity, 7-linear inductor Fig.11 Schematic of physical simulation experimental apparatus Note: The size of mould cavity is: 500mm, 100mm and 1mm in length, width and height

  21. HIT a) b) c) d) Fig.12 Filling processing of Ga melt in the mould and the final state under different conditions a) Bz=0mT, b) Bz=12.5mT, c) Bz=27.5mT, d) Bz=42.5mT

  22. HIT (a)660 ℃ (b)700 ℃ (c)740 ℃ (0At) (a) 740℃ (b) 700℃ (c) 660℃ (1860At) Fig.13 Al-12Si alloy plate samples cast by TMFC Note: Cavity size of the ferromagnetic cope:570x140x3mm

  23. HIT Fig.14 Effect of magnetic field intensity on the filling area and time

  24. HIT Fig.15 Effect of travelling magnetic field on the filling area proportion of Al-12Si alloy at different pouring temperatures

  25. HIT 5.MAIN DEFECTS

  26. 1cm HIT a) b) c) a) Cold shut and b) Misrun are related to the flow characteristic of molten metal c) Pit surface is related to the magnetic field intensity of y direction Fig.16 Main defects of Al plate cast by TMFC

  27. HIT 6.CONCLUSIONS

  28. HIT Summary The magnetic field intensity decreases quickly with increasing the distance from the surface of the inductor. The component By and Bz get the maximum values at the slot and tooth respectively. Over the inductor, more space is By>Bz. Travelling magnetic field can enhance the mould-filling velocity remarkably. For Al alloy melt of 660oC, the mold cavity with 570mm in length, 140mm in width and 3mm in thickness can be filled fully under the condition of 43.9mT. While under gravity, the melt can flow only 50mm in length. Travelling magnetic field also cause negative effect on the castings., the velocity of the melt front increases quickly because of electromagnetic force during filling processing and this results in the decrease of the cross section area of the forward filling melt. This is the reason of the misrun or cold shut formation. Another problem is pit surface on the bottom surface of the plate casings. Its formation reason is existed y direction electromanetic field.

  29. Thanks for your attention!

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