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Roasting and melting process
2024-08-30 16:37:24
During the precision casting process,Roasting and melting are connected processes, completed by the same group of personnel, the roasting process, the temperature of the shell mold, dryness and other factors directly affect the quality of the final casting, melting and pouring process, the temperature of the molten steel, slag removal, deoxidation and other factors also play a decisive role in the quality of the casting and the qualification rate,The two processes are also the root cause of many quality problems in the investment casting process, so how to control these two processes will directly determine the quality of the product.
Working hours:
Due to the high power equipment used for roasting and smelting, we usually start our work in the evening, from 20:00 to 08:00 the next morning.
Roasting work content
1.Preparation
1.1 Check the roaster and temperature control system for proper functioning
1.2 Roaster bed needs to be cleaned
1.3 Clearly distinguish the material and model of the product in each furnace, and fill in the material, model and other process parameters in the "melting and burning flow sheet".
2.Roasting operations
2.1 Start the gas stove to ignite and warm up ( Figure 1)
2.2 Furnace loading personnel should carefully check the shell mold to be sintered, the shell mold should be intact without defects, defective shell mold must be repaired before the furnace
2.3 Every furnace time to clean the shell mold placed on the table, take the shell mold must be cleaned up the edge of the sprue cup sand particles and then put on the table, clean up the edge of the sprue cup always when the sprue cup should be down to prohibit the upward (Figure 2)
2.4 Before loading the furnace, first check the furnace residual shell mold and shell mold pouring cup mouth debris, pouring cup down carefully shell mold forked into the roasting furnace, the arrangement should not be too dense (before and after the left and right spacing in the 20 ~ 30mm) in order to avoid burn through (Figure 3); sintering temperature according to the "product technology card" and determine (Figure 4), sintering temperature requirements of the high, after the pouring of the shell mold is first loaded into the furnace, the shell mold distance from the door of the furnace to be in the 300mm or more!
2.5 Shell molds (materials) are different and require different sintering temperatures, so shell molds must be loaded into the furnace separately and must not be mixed.
2.6 When changing the material, the number of shell mold strings should be estimated first so that all the molds can be poured.
2.7 Shell mold in the sintering process, sintering personnel must open the door every 15 minutes to observe the furnace sintering, according to the situation to adjust the size of the fire, sintered shell mold should be rose-colored (white with red)
2.8 Sintering furnace to cooperate with the melting furnace, to ensure that the pouring shell mold has been burned, when the steel can be qualified to pour, fork out the shell pouring, the requirements of the shell from the sintering furnace forked out to the pouring of no more than 10 seconds, the furnace worker out of the furnace must be based on the direction of the flow of steel to adjust the position of the shell mold to prevent the steel from scattering
(Figure II)
(Figure III)
(Figure IV)
Contents of casting work
1.Preparation
1.1 According to the "equipment operating procedures" to check the furnace: furnace lining induction ring, cooling water pipe, furnace body rotation mechanism is normal, such as the need to repair should be repaired in a timely manner.
1.2 Check the power supply and electrical control system for proper functioning
1.3 Prepare tools and temperature measuring instruments, etc.
1.4 Start the cooling water system (Fig. 1), open the power switch (Fig. 2) and the cooling water switch of the furnace inductor ring (Fig. 3), the cooling water pressure is more than 0.15MPa, and check whether the cooling water in each way is free from obstruction.
1.5 Check that the material of the charge matches the material of the baked shell.
(Figure I)
(Figure II)
(Figure III)
2.Charging, melting
2.1 The base material (such as Ni, Cr-Fe lack of iron, 304 edges, rolls of material) in the loading loaded, and oxygen affinity of the alloy of the original element must be added in the deoxygenation of good conditions. (All furnace charge must fill in the "alloy ratio, alloy record sheet")
2.2 Some refractory alloys are contained in crucibles with the lower high-temperature zone
2.3 Large pieces of material loaded in the lower part of the gap in the large pieces of material with a small material to fill tightly, and strive to achieve "tight down on the loose" to prevent "bridging" and accelerate the melting speed (Figure 4)
2.4 Long charges should be placed straight
2.5 Open the furnace, open the power switch, check whether the capacitor contactor is locked, whether the power control knob is at zero, open the frequency converter "open" button, rotate the power control button in the clockwise direction, so that the electric frequency power supply starts to slowly increase the power until the maximum.
2.6 Maintain the power, with the melting of the charge, one after another will not be loaded with the material to join, in the melting process should be timely pounding, in order to prevent the occurrence of "bridging". (Figure V)
2.7 Reach the rated power and the furnace charge all melted, in time to cover the liquid surface of the molten steel with the slag removal material, (Figure 6) melting often check the cooling water of each circuit, especially the cooling water of the induction loop, the water temperature shall not exceed 30 ℃, but also to observe the condition of the furnace lining.
(Figure IV)
(Figure V)
3.Adjustment of composition and deoxygenation
3.1 When the charge is clear, take samples to analyze the composition, according to the results of the analysis of the composition of the adjustment, the first deoxidation or the first alloy, the adjustment of the composition to be added by the specific types of alloys
3.2 When the liquid steel to reach the deoxygenation temperature, that is, with Si-Ca particles (or composite deoxidizer) for diffusion deoxygenation, each remove a batch of slagging agent to join a batch of deoxidizing system, repeated many times (generally 5-6 times) remove the slagging agent and the deoxidizing agent between the time should be short to prevent the surface of the steel in the air exposure road for a long time and the occurrence of oxidation
3.3 Finally add the alloy element sampling analysis of composition, according to the analysis results of the composition adjustment, and finally measure the temperature of the steel, the temperature up to meet the requirements of the "product process card" can be out of the furnace.
4.Pouring out of steel
4.1 In the liquid steel composition and temperature to meet the requirements, deoxygenation has been completed, power outage slagging, blowing the furnace surface and out of the steel nozzle on the gray sand, the power will be adjusted to the heat preservation is ready to out of the steel
4.2 Forks are used to remove the mold shells from the roaster during casting in the induction furnace (Fig. 7)
(Figure VI)
(Figure VII)
4.3 Align the gating cup with the steel outlet of the induction furnace, rotate the induction furnace body, fast pouring (Figure 8), pouring diversion should be accurate, fast speed, to prevent the liquid steel fly liquid, broken flow
4.4 Keep picking the mold shell to the front of the induction furnace with a fork, keep pouring continuously and finish the steel as soon as possible
4.5 After the casting of the mold shell to stabilize and then add a little riser insulation agent cooling, the mold shell will be sent to the designated location, divided into furnaces placed, and at the same time, do a good job of furnace number marking (Figure 9)
5.Furnace shutdown
Rotate the power control knob to "zero" position, turn off the frequency converter, cut off the power, reduce the pressure of cooling water to slow down the cooling time of the furnace body to avoid cracking of the furnace lining, after stopping the furnace, the cooling water to keep (crucible inside the raspy color) for 5-6 hours, stop the cooling water!
6.Do a good job of opening furnace records, fill out the "melting flow sheet". Do a good job of workshop 5S, fill out the "equipment maintenance record sheet"
As a precision casting factory specializing in the production of stainless steel, copper alloy parts, we have many years of experience in supporting automotive parts, and cooperation with a number of well-known enterprises at home and abroad, the quality management of the three non-principles, that is, "do not receive defective products, do not manufacture defective products, do not produce defective products," has always been the management philosophy that we have been recognized by our customers, listening to our customers, serving every customer is our purpose and the driving force behind our development. This is also the place where we have been recognized by our customers. Listening to our customers' voices and serving every customer is our aim and the driving force for our development.