The appearance of the induction furnace undoubtedly enhanced the development of science and technology. Its main purpose is mostly used for steelmaking. New steelmaking methods for induction melting furnace refining equipment continue to appear. At the same time, the quality of molten steel is greatly improved, and the quality of castings is greatly improved.
Electric arc furnaces and induction electric induction furnaces commonly used in steel casting workshops have relatively loose requirements for raw materials, the quality of molten steel produced is high, and the steelmaking cycle is suitable for the characteristics of cast steel production. It is convenient and easy to start and stop the furnace. It is coordinated with the progress of modeling, box closing and other processes to facilitate the organization of production. In addition, the equipment for electric furnace steelmaking is relatively simple, with low investment, infrastructure construction speed and fast fund recovery.
In recent years, induction melting furnace steelmaking has developed rapidly. The induction furnace steelmaking process is relatively simple, and the quality of molten steel can also be guaranteed. Many factories use induction furnace steelmaking to cast small castings, especially investment precision casting workshops, which widely use induction electric furnaces to melt molten steel. So how does an intermediate frequency furnace make steel? Let’s take a look at it together.
How does a Foundry melting furnace melt steel?
1. The first is the preparation for steelmaking in the intermediate frequency furnace: When preparing for steelmaking, the preliminary inspection work should not be neglected. It is necessary to understand the condition of the furnace lining, whether the production tools are complete, and whether the panel of the intermediate frequency furnace is normal.
2. Every two furnace bases are a set, and the necessary products such as ferrosilicon, medium manganese, synthetic slag, heat preservation agent, etc. must be prepared in place and placed in the middle of the furnace.
3. The steel material must be in place, and the furnace cannot be started if the steel material is not fully prepared.
4. Pay attention to the insulating rubber bedding of the intermediate frequency furnace, and it is strictly forbidden to leave any gaps.
Followed by the attention when the induction furnace steelmaking enters the production stage:
1. The new furnace lining shall be baked in strict accordance with the requirements of the new furnace baking process, and the baking time should be greater than 2 hours. The new furnace lining shall be baked in strict accordance with the requirements of the new furnace baking process, and the baking time should be greater than 2 hours.
2. First add a small suction cup to the furnace to protect the furnace lining. It is not allowed to directly add large pieces of material into the empty furnace, and then turn on the electricity. At this time, the furnace front worker should add the small materials scattered around the furnace into the furnace in time, and it is strictly forbidden to drop it. The stovetop and silicon steel sheet punch is only allowed to be used during the oven, and are not allowed to be used during the rest of the time.
3. The disk hoist lifts the material onto the stove from the stockyard, and the front workers sort the scrap steel. The sorted flammable and explosive materials are directly placed in the special collection box and registered and confirmed by the stove security.
4. The special collection box for flammable and explosive materials is placed between the two sets of furnace bases, and no one can move it at will.
5. The feeding in front of the furnace is mainly manual feeding. After the stove scrap is carefully sorted, the length of the material is less than 400mm, and the material that has been carefully selected by the furnace manager can be added by the suction cup. The driving commander is the small of each furnace seat. Furnace master, if other people command the driving suction cup to feed, the driving operation is not allowed to feed.
6. The amount of suction cup feeding should be controlled. After adding, the scrap steel is not allowed to exceed the surface of the furnace mouth of the intermediate frequency furnace. The scrap steel scattered around the furnace mouth should be cleaned up with suction cups. During the feeding process, the surrounding area of the intermediate frequency furnace must be kept clean to prevent the induction coil or cable joint from igniting due to the falling of the scrap steel.
7. It is strictly forbidden to pile a large amount of scrap steel on the platform, and the total amount is controlled within 3 suction cups to reduce the difficulty of scrap sorting.
8. In the event of an explosion, the operator should immediately turn his back to the furnace’s mouth, and quickly move away from the scene.
9. During the pre-feeding process, the long and large materials must be erected and added to the furnace to melt them into the molten pool as soon as possible. It is strictly forbidden to add them flatly to cause bridging. If the furnace material is found to be bridging, the bridge must be destroyed within 3 minutes. The charge is quickly melted into the molten pool. If the bridge cannot be destroyed within 3 minutes, the power must be cut off or the bridge must be destroyed in the heat preservation state before the power can be sent for normal smelting.
10. For some scrap steel that is overweight and needs more than 2 people to move into the furnace, it is strictly forbidden to throw it into the furnace. A transition should be made on the furnace edge, and then carefully pushed into the furnace.
11. The tubular scrap is added to the furnace, and the upper mouth of the pipe should be in the direction of tapping, and it is not allowed to be in the direction of manned operation.
12. For the cold steel and short-end continuous casting slab in the slag ladle and tundish, the molten steel in the intermediate frequency furnace should be erected into the furnace after it reaches 2/3 or more, and it is not allowed to hit the furnace lining.
13. When the molten steel in the induction furnaces reaches more than 70%, take samples for analysis. The samples shall not have defects such as shrinkage holes, and no steel bars shall be inserted into the sample cups. After the chemical composition results of the samples come out, the person who prepares the elements shall determine according to the comprehensive situation of the two furnaces. The amount of alloy added.
14. If the result of chemical analysis in front of the furnace shows that the carbon is high, add some iron oxide nuggets for decarburization; if it shows that the carbon is low, add some pig iron nuggets for recarburization; if the average sulfur of the two furnaces is less than or equal to 0.055%, the rakes will be exhausted during tapping. Oxidized slag, increase the amount of synthetic slag added for desulfurization. At this time, the steel tapping temperature must be appropriately increased. If the average sulfur of the two furnaces is ≥0.055%, the molten steel should be treated in a separate furnace, that is, a part of the high-sulfur molten steel is poured into the ladle Put it into other furnaces, then add some silicon steel sheet punches into the two furnaces for smelting and then tapping. In case of high phosphorus, it can only be processed in a separate furnace.
15. After all the scrap steel in the furnace has been melted, the group in front of the furnace will shake the furnace to pour the slag. After pouring the slag, it is strictly forbidden to put wet, oily, painted and tubular scrap into the furnace. Dry and clean materials are in the smelting process. It should be prepared. After the molten steel in the furnace is full, clean the slag again. After cleaning, quickly add the alloy to adjust the composition. The steel can be tapped more than 3 minutes after the alloy is added. The purpose is to make the alloy have a uniform composition in the furnace.
16. Tapping temperature: Upper continuous casting 1650—1690; molten iron about 1450.
17. Measure the temperature of the molten steel in front of the furnace, and control the power transmission curve according to the tapping temperature and tapping time required for continuous casting. It is strictly forbidden to keep the intermediate frequency furnace in the high-temperature stage (the temperature of the heat preservation is controlled below 1600℃)
18. The temperature rises quickly after receiving the notification of continuous casting steel tapping. The heating rate of the intermediate frequency furnace in the full liquid state of the furnace: about 20℃/min before 20 furnaces; about 30℃/min for 20-40 furnaces; approximately 30℃/minute for furnaces above 40 40℃/min. At the same time, note that the higher the temperature in the furnace, the faster the heating rate.
19. When the first furnace is tapped, 100 kg of synthetic slag is added to the ladle for heat preservation, and after the second furnace is tapped, 50 kg of covering agent is added to the ladle for heat preservation.
20. After the induction melting furnaces are finished, check the lining condition carefully, and it is strictly forbidden to pour water into the furnace to cool down; if some parts of the furnace lining are severely corroded, the furnace should be repaired carefully before starting the furnace. After the furnace is repaired, the water in the furnace must be waited for. Feeding can only be done after all the parts have evaporated. First, add a suction cup silicon steel punch in the furnace, and then add other scraps. The first furnace after repairing the furnace should control the power supply curve, so that the furnace lining has a sintering process to ensure that the furnace is repaired. As a result, it is strictly forbidden to add large pieces of waste to the furnace immediately after repairing the furnace.
21. During the whole production process, it is strictly prohibited to expose the furnace panel to the outside, and the insulating rubber should be replaced in time if it is damaged.