1 , an induction melting furnace process requirements

1.1 Melting time 100kg molten steel is less than 30rain

1.2 The pouring temperature depends on the size of the casting and the thickness of the wall. It is generally 80-120 °C higher than the melting point of the metal (liquidus).

1.3 Deoxidation: the general part is pre-deoxidation + final deoxidation;

The pre-deoxidizer was added in an amount of 0.2% ferromanganese. 0.25~0.3% ferrosilicon.

The final deoxidizer is added in an amount of 0.15 to 0.2% silicon calcium or 0.06 to 1% aluminum.

2, induction melting furnace operating procedures

2.1 Preparation

2.1.1 Check the condition of the furnace: whether the furnace lining, copper tube induction coil, cooling water pipe, furnace body rotation mechanism, etc. are normal. If the furnace lining needs to be repaired, it should be repaired first.

    2.1.2 Check if the power supply voltage and electrical control system are normal.

    2.1.3 Prepare tools and temperature measuring instruments.

    2.1.4 Start the cooling water system to check the water pressure. The cooling water pressure of the copper tube induction coil is not less than 0.2Mpa, and the intermediate water machine cooling water pressure is 0.08~0.12Mpa: check the joint position and the cooling water pipeline for leakage. Whether it is smooth and normal, if there is any problem in time, the report that cannot be processed can be quickly solved by the production supervisor or maintenance worker.

2.2 Loading: According to the molten steel number and the lining condition, the alloy with less burning loss can be added to the bottom of the furnace. Then add the pre-washed new material. The coarse and fine materials are used together, the bottom pad is small material, the middle size is matched, and the upper part is enlarged. The charge generally does not exceed the height of the induction coil; the long charge is placed vertically into the furnace and strives to "tighten and loosen".

2.3 Melting

2.3.1 Power-on and open: After turning the “intermediate frequency power” rotary switch to the “zero” position in the counterclockwise direction, start the (pulled power) button, and then return the 630A air switch from the left side to the next position. Push up in place. At this time, the “main circuit” green indicator on the control panel lights up, and then the “inverter start” button is activated, so that the “inverter work” green indicator light is on. At this time, “intermediate frequency power” is rotated clockwise. Switch, slowly increase the frequency and power until the limit indicator lights up.

2.3.2 Maintain the power limit, and add the unfilled materials as the charge melts. During the melting process, the material should be diverted in time to prevent explosion accidents caused by bridging. When the "bridge" problem occurs, the power should be cut off in time or the power should be reduced to tilt the furnace to a certain angle, so that the lower high-temperature metal melts the "bridge" low-temperature surface. When the melt is opened, there are a large number of air waves or a large amount of slag. When rushing out, the air should be sprayed or the slag should be destroyed. At this point, the furnace age and furnace lining conditions should be analyzed calmly to determine whether to continue to open the furnace or to abandon the furnace lining.

2.3.3 When the rated power and all the furnace materials are melted and cleared, check whether the cooling water drainage is smooth and the drainage temperature should be lower than 35 °C. And should pay attention to cover the molten steel level.

2.4 Deoxidation and adjustment of ingredients: When the charge is cleared, sample the fractions. According to the results of the division, the composition is adjusted. First, deoxidation or alloy adjustment is required. It depends on the specific alloy type. Deoxygenation is usually divided into two parts: pre-deoxidation and final deoxygenation. After the furnace material is cleared and warmed up, pre-deoxidation can be carried out. Ferric iron is added first, then ferrosilicon is added or a composite deoxidizer is added at one time, and then the molten steel ( melting ) temperature is measured. When the molten steel composition and temperature are suitable, the final deoxidation is performed. .

2.5 Casting of steel tapping: static electricity is set, the steel slag is removed by slag-forming agent, and the furnace and tapping port are cleaned and tapped.

2.6 Shutdown: Turn the intermediate frequency power control knob to “zero” position, press the “inverter stop” red button after 2 minutes; press the “main circuit minute” red button: then press the “control circuit minute” red button. When the IF unit has been powered off ( if there is an accident in the middle of melting , it is still necessary to turn off the power according to the above steps before checking the energized part of the induction furnace). Reduce the cooling water pressure, cover the furnace mouth with a cover to delay the cooling time of the furnace body, to reduce or avoid the crack of the furnace lining. Turn on the furnace cooling water system time switch and stop the furnace for at least 6 hours.

3. Note:

3.1 The adjustment of the composition should be reasonable in the order of alloy addition, and the temperature at the time of addition should be noted. All alloys added to the element must be pre-heat treated and overweight.

3.2 Some refractory and dense elements should be added first; alloy elements with higher affinity for oxygen must be added under good deoxidation conditions, and the temperature should not be too high when added to reduce burning loss.

3.3 Each time an alloying element is added, the heating time must be determined according to the amount added. When adding more aluminum and titanium, it is necessary to stop the power and cool down.

3.4 Strict deoxidation procedures should be carried out. After the final deoxygenation, the casting time is as short as possible, and the high temperature melting and static treatment stage must be carried out before deoxidation .

3.5 During the whole melting process, the number of slag removal should not be too much. Too many slag removals can cause the alloy liquid to inhale and oxidize. The slag removal agent must be strictly baked before use.

3.6 Operate and maintain in strict accordance with the operation and maintenance requirements of the equipment.

3.7 During the melting process, it is necessary to check the condition of the furnace lining to prevent the furnace from being worn. Observe and check the abnormal noise and drainage conditions of the IF unit and the furnace. If there is any abnormality, check the power failure and record or notify the maintenance.

3.8 The melting personnel shall wear overalls. Anti-scalding shoes and melting glasses. Gloves, etc.

3.9 The molten charge is first confirmed to have a non-aqueous portion, and no hollow closed tubular container is added. The backing material die pouring cup is added upward to prevent the molten steel from splashing and injuring people.

3.10 If there is a power outage and other factors, the internal and external circulating water will not work properly. The emergency water switch should be turned on in time. To ensure that the intermediate frequency cabinet and furnace body are not damaged.

3.11 Make a record, fill out the report, and complete the handover procedure.